PART II
LECTURE AND PRACTICAL EXERCISES

Lecture 1
COASTAL RESOURCES OF ASIA-PACIFIC: ENVIRONMENTAL ASPECTS¹

by
Edgardo D. Gomez²

ABSTRACT

This lecture was delivered orally. No hand-out was distributed.

As the most productive zone of the ocean, the coastal zone has been exploited heavily in the Asia-Pacific region. Being the closest to land and, therefore, the most accessible to man, the coastal zone and its resources are also the most vulnerable to pollution and other influences that result in the degradation of the coastal environment.

Recent studies in Southeast Asia have indicated same trends. The destruction of naturally productive ecosystems such as coral reefs and mangrove swamps continues as a serious concern. The disposal of wastes, particularly sewage, is a growing problem near many population centers, sometimes correlated with negative public health effects. While various pollutants such as oil and heavy metals are evident in some localized areas such as industrial centers, chlorinated hydrocarbons are more widespread and need to be monitored.

As a whole the region shows a growing awareness of marine environmental problems and some measures are being undertaken to address the concerns.

The environmental aspects dealing with contamination of marine environments and problems related to the development of the seaweed industry were discussed in general. Marine water pollution and levels of contamination in seaweeds were also discussed. Areas of research and development programmes towards appropriate management of the coastal resources in this region were given.

¹ The paper is not available; for inquires write to the author,

² Professor and Director, Marine Science Institute, College of Science, University of the Philippines Diliman, Quezon City, Philippines.

Lecture 2
STATUS OF SEAWEED PRODUCTION AND UTILIZATION IN ASIA

by

Gavino C. Trono, Jr.¹

1. INTRODUCTION

Due to the archipelagic nature of many Asian countries, it is inevitable that a significant portion of the population is located along the coastal areas. The lives of the people in these areas are therefore, intimately associated with the sea and its resources. Due to their distance from urban and industrial centers, the people in the farflung coastal areas are not benefited by modern development.

Coastal areas in many Asian countries are characterized by well-developed coral reef which originally support rich fishery resources. The rapid increase in population and its concomitant increasing demands for fishery products, however, are exerting a tremendous pressure on the productivity of these resources. As a result, many of the coastal areas are at present experiencing the ill effects of overexploitation. Alternative sources of food and livelihood for the coastal inhabitants are therefore necessary.

With a few exceptions, the seaweeds are among the coastal resources which have not been developed in many countries in Asia. Many species of seaweeds with high economic value are found in the shallow reefs and bays. The principal genera of seaweeds presently being utilized in Asia are listed in Table 1. The production of seaweeds offer a good alternative as source of food and cash income for the coastal inhabitants.

¹ Professor, Marine Science Institute, College of Science, University of the Philippines, Diliman Quezon City, Philippines and Training Director, Seaweed Farming Training Course, 2–21 May 1988.

Table 1. Principal seaweed genera of economic potentials in developing countries in Asia

2. WORLD SEAWEED PRODUCTION

Although there are no accurate data on the world production of seaweeds yet it is apparent that total world seaweed production is sizeable and will continue to increase in the future due to the expanding uses of seaweeds and seaweed products. Naylor (1976) estimated that approximately 1170 000 MT were produced in 1960 (Table 2). Production increased to approximately 2 400 000 MT in 1973 valued at US$765 million. The bulk of production was contributed by Japan, China, Korea, USA, Brazil, Norway and other countries in Europe. Except for the above mentioned countries in Asia, very little was contributed by the developing countries in Southeast Asia. India has been producing small quantity of seaweeds since 1960. Indonesia started producing in 1968 up to about the early part of 1970's to the present. The Philippines contributed very little from 1960 to about 1973 but her production significantly increased in 1974 up to the present. Thailand recorded very small production from 1967 to 1972 while Malaysia and South Vietnam did not produce any from 1960 to 1973.

Table 2. World production of seaweeds (1960 and 1973) and estimated value (1973)

( ) Broad estimates of production

¹ Some figures, e.g., Japan, U.K., Argentina, Morocco are officially published data converted into U.S. dollars at average exchange rates for 1973; others, e.g., Korea, Spain are estimates based upon relative data for 1972; for a number of countries, notably China, U.S.S.R., U.S.A., Brazil, the estimates are broad indications calculated on the basis of the species composition of the harvest, uses of the weeds and unit production values elsewhere.

From: Naylor, J. 1976. Production, trade and utilization of seaweeds and seaweed products. FAO Fisheries Technical Paper No. 159.

3. STATUS OF PRODUCTION IN ASIA

Except for China, Japan and Korea where the seaweed industry is well established, the rest of the developing Asian countries are still dependent on wild seaweed crops. The Philippines may be cited as an exception, but actual farming is still limited to three species, namely: Eucheuma alvarezii, E. denticulatum and Caulerpa lentillifera. Indonesia is presently producing a certain amount of Eucheuma. Thailand is starting her Gracilaria culture project. The rest are still dependent on wild crops.

Production from wild crops is unreliable and is highly dependent on the natural growth of the species and the harvest rate exerted on the local stocks by the gatherers. Post-harvest methods used are generally antiquated resulting to the poor quality of the produce. In addition, the absence of a management programme for the naturally produced species often results to the depletion and/or destruction of their natural stocks. In contrast, the production of sea-weed species through farming is reliable. The rate of production can be programmed based on the demand. It is a very efficient way of conserving the local stocks. In addition, it is labor-intensive thus, offering more job opportunities to unskilled and otherwise underutilized labour force in the coastal areas. Seaweed farming is also a very good alternative in areas where small-scale fishing activities had become unproductive due to depletion of coral reef-associated fish species. Farm-produced seaweeds are generally of higher quality due to the application of highly improved post-harvest handling methods.

4. UTILIZATION OF SEAWEEDS AND SEAWEED PRODUCTS

Except in Japan, China and Korea where seaweeds and seaweed products are standard components of meals of the bulk of the population direct utilization of seaweeds as food in other Asian countries is limited to a small portion of the population along the coastal areas. Many species of seaweeds are eaten as vegetable salad and prepared in various ways. Seaweeds in general with the exception of some species are of low nutritional value due to their low protein content and generally hard-to-digest carbohydrates. However, they are important source of minerals, vitamins and roughage. Seaweeds are good food supplements and cannot totally replace the staple foods such as rice, fish and other cereals. Among those which are utilized directly as food are the following: E. alvarezii, E. denticulatum, species of Caulerpa, Porphyra, Codium, Hypnea, Laurencia, Hydroclathrus, Acanthophora and Sargassum.

Some genera of the brown algae such as Sargassum are also utilized as raw materials for the manufacture of animal feeds. At present, this genus is being harvested in commercial quantities for this purpose. A major portion of the local harvest is exported to Japan while the rest is used in the local manufacture of feeds. In India Sargassum is harvested in commercial quantities as raw material in the manufacture of alginates for their textile industry.

The most important use of seaweeds in Asia at present is as an item of commerce. The high demand for tropical seaweeds in the international market as raw materials in the manufacture of commercial products such as agars, carrageenans and alginates was the primary factor which influenced the development of farming technology for some seaweeds like Eucheuma. The farming of Eucheuma is a very productive small-scale industry which can be an alternative fishing activity in shallow coastal areas. During the 70's however, Eucheuma was sold in inter-national market in an unprocessed form due to the absence of processing technology. Asian countries buy the processed product (carrageenans) from foreign processors or suppliers at a much higher price for application in local industries. Today, a significant portion of Eucheuma produced through farming are sold in international market in treated (chips), semi-refined and refined forms. Portions of local produce of other seaweeds such as Gracilaria, Gelidiella and Gelidium are processed into crude agar which are sold in local markets in the form of dried agar bars. Except for Caulerpa production of other seaweeds is derived and is dependent up to now on natural stocks. Pond cultured Caulerpa are presently produced in the island of Mactan in Cebu. These are locally sold in open markets of Metro Manila, Cebu City, Cagayan de Oro City and Zamboanga City. Presently, a significant portion of the produce is exported to Japan and Okinawa in partially dehydrated (salted) form. All Sargassum processed in Central Visayas are exported to Japan while those in Northern Mindanao are locally utilized in the manufacture of feeds. A significant amount of Gracilaria and Gelidiella is exported while the rest is locally processed into agar bars. Production of other genera such as Codium, Hypnea and Porphyra is dependent on natural stocks and the produce is locally consumed.

The data on Philippine seaweed exported (Table 3) show that the volume of seaweeds presently exported had increased almost fifty times over that of the 1967 production. Starting as a minor sea product, seaweeds at present rank No. 3 among the fishery exports in the Philippines behind such pro-ducts as shrimps and tuna.

Table 3. Philippine seaweed export

Source: Exports of fish and fishery product cleared by the Bureau of Fisheries and Aquatic Resources, by kind, quantity (in kilograms) and value, fisheries statistics, 1967–1980.

REFERENCES

Doty, M.S. 1977 Seaweed resources and their culture in the South China Sea Region. SCS/77/WP/60. Manila, 19p.

Michanek, G. 1975 Seaweed resources of the oceans. FAO Fish. Tech. Paper No. 138.

Naylor, J. 1976 Production, trade and utilization of seaweeds and seaweed products. FAO Fish. Tech. Paper No. 159.

Trono, G.C., Jr. 1981 The present status of seaweed production and utilization in Asia. In G.C. Trono and E.T. Ganzon-Fortes (eds.) Report on the training course on Gracilaria algae. SCS/GEN/81/29: 41–44. South China Sea Fisheries Development and Coordinating Programme, Manila.

Lecture 3¹
SEAWEED ECOLOGY: INFLUENCE OF ENVIRONMENTAL FACTORS ON THE STRUCTURE, PHENOLOGY AND DISTRIBUTION OF SEAWEED COMMUNITIES

by

Gavino C. Trono, Jr.²

1. INTRODUCTION

The environmental conditions regulate the kind, nature, abundance and productivity of seaweed communities.

The stature of the community is reflective of the environmental conditions in the area.

Different kinds of species are found in certain habitats because environmental conditions are favourable to their development.

2. ENVIRONMENTAL FACTORS

The ambient ecological condition in a certain habitat is the result of the combined and synergistic effects of the various ecological factors. Some of these factors may exert modifying effects on the others. The understanding of the influence of these parameters on the nature, biology and distribution of seaweed is important in the evaluation and assessment of sites for mariculture purposes.

2.1 Salinity

Salinity is defined as “the amount of solid materials in grams contained in one kilogram of seawater when all the carbonate has been converted to oxide, bromine and iodine replaced by chloride and all the organic matter completely oxidized”.

Most seaweed species cannot withstand . exposure to a wide variation in salinity regimes while others can. Those which cannot tolerate wide range of salinity regimes are known as stenohaline species while those which can are called euryhaline species. The effects of salinity on the structure of seaweed communities may be best illustrated by comparing the variety of species found in habitats which are influenced by freshwater (brackish) with those far from freshwater sources. Areas influenced by freshwater are generally characterized by low species diversity compared to reef areas not influenced by low salinity. The low diversity may be mainly due to the fact that only few species can thrive in habitats with highly fluctuating salinity regimes. For instance, certain species like Glacilaria verrucosa thrives very well in brackishwater areas while other species will die in such habitats.

2.2 Light and temperature

All photosynthetic plants require light as source of energy for the synthesis of organic products necessary for their normal growth and development. The different groups of seaweeds possess pigments of various types which enable them to adapt to different light conditions in the sea.

The quality and intensity of light change as it penetrates the water column. The change in light quality and intensity affects the distribution of the various species. The influence of light on seaweed distribution is best illustrated by their vertical zonation. In general those with pigments adapted for low intensities may be found in deeper areas while those adapted to full or bright conditions are found in shallow areas.

Heating of the water is a secondary effect of light which also affect the local distribution of seaweed species. Such effects, however, are limited to shallow intertidal areas or tidepools which become isolated and are not influenced by free water circulation. In such habitats, the temperature may become very high and can cause the exclusion of many species from the area. Such pronounced increase in water temperature takes place especially when low tides occur during the day. There is no significant change in water temperature in deeper areas where the water is constantly mixed by currents or wave action.

2.3 Substratum

Substratum provides mechanical support or attachment of the seaweeds. Seaweeds have different types of attachment organs adapted to various types of substrata. For instance, those species found in sandy-muddy habitats are generally characterized by fine and penetrating rhizoidal holdfasts while those in solid, hard or rocky substrates are characterized by strongly developed, branching or discoidal holdfast. Thus, the different types of substrate influence the composition and local distribution of seaweed species. The awareness of the role of substrates on the local distribution of seaweeds is thus, very important in inventory and stock assessment survey work.

2.4 Water movement

Water movement is an overall primary factor which controls or influences the nature or status of seaweed communities as well as modifies or moderates the extreme effects of other ecological factors. Water movement caused by waves and currents is important in aeration of the water, nutrient transport and mixing which prevents the rise in water temperature as well as light penetration. It also influences the amount of harvestable seaweed stocks. Waves are known to mechanically remove significant amounts of seaweed stocks. This effect is best illustrated by the tremendous amounts of drifted seaweed materials which accumulate along the beaches after storms. Wave-exposed areas are not good sites for the mariculture of seaweeds because of the destructive effects of waves on the farm. On the other hand, areas influenced by moderate currents are preferred sites for farming of certain species such as Eucheuma because currents are less destructive. Productive Eucheuma farms in the Philippines are characterized by moderate to strong currents. Loss of plants due to removal by currents can be significantly controlled by the construction of catchments at the lee-ward side of the farm.

2.5 Water depth

The water depth is another important factor which influences the local abundance and distribution of seaweeds. The upper limit of the vertical distribution of seaweeds is closely related to the upper tidal levels while the lower limit is limited by the amount of light which penetrates the water column. In general, most seaweed communities are well-developed starting from approximately plus or minus the 0 datum level to a few meters below this depth. The upper limit of vertical distribution of seaweed is influenced by the amount of exposure to air and sunlight during low tides and the inherent capacities of the species to resist dessication and the complications brought about by changes in salinity and water temperature during such exposure. The lower limit is generally related to the light conditions. Few species can thrive well in very low light intensities in deeper areas.

The understanding of the role of water depth in the vertical distribution and growth of seaweeds has a very important bearing in the selection of good sites for seaweed farms.

2.6 Biotic factors

One of the ever present factors which controls the marine vegetation are the associated animal life. Seaweeds and seagrasses are constantly being grazed upon by a host of animal grazers. These animals significantly control the amount of harvestable organic matter (biomass) in reef areas. Studies have shown that when grazing is controlled by the physical destruction or removal of grazers, luxuriant growth of seaweeds would follow.

Fungal and bacterial diseases are recognized as important biotic factors which influence the productivity of seaweed communities. These two factors are important considerations in the farming of seaweeds. Seaweed crops may be completely lost due to the destructive effects of these biotic factors. The presence of “weeds” is also one of the major problems in farms. These unwanted seaweed species compete with the crop plants for nutrients, space and light.

2.7 Other factors

Dissolved gases such as oxygen and carbon dioxide seldom become limiting factors to the growth and development of seaweed communities. These gases are abundant in the sea where there is continuous mixing of water due to the action of waves and currents. Oxygen comes from two major sources, i.e. from the atmosphere and as by-product of photosynthesis. Aeration of the water column is facilitated by waves and currents. Carbon dioxide which is a principal raw material in the production of organic substances through photosynthesis is present in abundance in the sea as dissolve gas or in the form of carbonate compounds. Another factor which seldom becomes limiting in the sea is pH. The buffered nature of seawater does not allow extreme fluctuation in pH values except in special types of habitats such as tidepools and isolated shallow lagoons especially during low tide regimes.

¹ Delivered by Dr. Miguel D. Fortes, Associate Professor, Marine Science Institute, College of Science, University of the Philippines, Diliman, Quezon City, Philippines.

² Professor, Marine Science Institute, College of Science, University of the Philippines, Diliman Quezon City, Philippines and Training Director, Seaweed Farming Training Course, 2–21 May 1988.

Lecture 4 and Practicum I
AN INTRODUCTION TO THE SEAWEEDS: THEIR CHARACTERISTICS AND ECONOMIC IMPORTANCE¹

by

Rhodora Azanza-Corrales²

1. INTRODUCTION

The primary producers or photosynthetic organisms in the marine environment are the algae and the seagrasses. Marine algae compared to the seagrasses and most terrestrial plants, are non-vascular and have simpler reproductive structures (Trainor, 1978). Seaweeds, unlike planktons, are macroscopic attached forms of algae.

This is a brief introduction to the major features of seaweed biology which are relevant to the understanding of the concepts and techniques in their resource management and culture. Economic benefits derived from these plants are also presented.

2. CYTOLOGY AND MORPHOLOGY

Aside from being useful as tools in seaweed taxonomy and nomenclature, knowledge of their cytological characteristics is important to appreciate the basic adaptations of sea-weeds at this lower level of organization. Thus, understanding at the higher levels of organization, e.g., organismic, population, community, etc., is facilitated.

The primary classification of the algae, i.e. at the division level is based on the following main criteria: (1) photosynthetic pigments, (2) food reserve, (3) cell wall components and (4) other important details of ultrastructure. It should be clarified, however, that classification is based on the combination of several characters (Annex A).

Except for the members of Cyanophyta, cells of most seaweeds are eukaryotic, hence, the structures where vital chemical processes occur are membrane-bound. To synthesize organic compounds with water and carbon dioxide in the presence of light as energy source, the seaweed utilize primarily chlorophyll a. Other major pigments are other chlorophylls, carotenoids and phycobilins. Photosynthetic pigments are contained in plastids generally discoid to ovoid in shape with less developed lamellae called thylakoids. These plastids or distinct containers of pigments are visible with light microscope in all seaweed divisions except in Cyanophyta. Blue green (Cyanophyta), green (Chlorophyta), brown (Phaeophyta) and red (Rhodophyta) seaweeds are so named because of their characteristic pigment combination (Dawes, 1981).

The biochemistry of their storage products and cell walls can also be used to differentiate seaweed groups. Starch (unbranched polymer of α l, 4 glucan as in higher plants) is the stored food in Chlorophyta while floridean starch (branched polymer of α l, 4 glucans and laminarin (polymer of β 1, 3 glucan) are found in Rhodophyta and Phaeophyta, respectively. Mannitol, an alcohol, found in many algae (Dawes, 1981) may be a common soluble food reserve in seaweeds. The basic component of the seaweed cell wall is cellulose (polymer of β 1, 4 glucan), however, other compounds as xylans (β 1, 3 linked) and mannans (β 1, 4 linked) can be found in coenocytic green algae. Patterns of cellular microfibril arrangement differentiate the various algal groups (Dawes et al., 1961; Dawes, 1966). Agar and carrageenan from some red algae and alginic acid from brown algae constitute the other (economically important) materials of their cell walls. Walls of many seaweeds have been known to have affinity for heavy metals which diffuse or are absorbed from the environment. Haug (1961) for example report that alginic acid has the following affinity for different metals: Pb>Cu> Cd> Ba> Sr> Ca> Co> Ni>Zn, Mn, Mg. This knowledge is important in choosing sites for culturing seaweeds. Culture or farming site should be far from sources of these pollutants which the seaweed can accumulate in their cells. Some (green and red) algae have calcium carbonate (Dawes, 1981), hence, are very important contributors to the calcium deposits in the marine environment.

The “thallus” (thalli, plural) refers to the seaweed's vegetative body with “roots”, “stems” and “leaves” which are structurally and physiologically less differentiated unlike their counterparts in vascular plants. The thalli range from smaller simple filaments to the bigger forms with “holdfast”, “stipe” and “blade”. The holdfast which attaches the seaweed to the substratum can be: (1) a modified basal cell, (2) rhizoidal filaments or (3) multicellular organs which may be disc-like or a branched system. The structure which may be present or absent between the holdfast and the blade is the “stipe” that grows terminally through the activity of a single apical cell or a group of them called meristem (Trono and Fortes, 1988). The “blade” wherein most photosynthesis occur is generally thin and expanded, but may be filamentous or fleshy, branched or unbranched. Storage (and transport) of photosynthate is not localized in one organ or structure unlike in vascular plants where the stem usually performs this special function. Vascularization, i.e. presence of phloem and xylem is absent except in the temperate groups. Laminariales and fucales (Phaeophyta) where beginnings of these tissues are present (Morris, 1967).

3. GROWTH, DEVELOPMENT AND REGENERATION

Life begins normally for a seaweed as a spore or a zygote (or propagules/cuttings in culture). Germination, growth and development proceed after settlement and attachment in the substratum leading to the formation of adult or mature plant that can then undergo asexual or sexual reproduction (Lobban el al., 1985). Evidences are mounting that aside from external factors as light, temperature, etc., internal ones as morphogenetic factors (like hormones) may be involved in processes that produce and maintain thallus integrity (Jacobs, 1985).

At some point/s in seaweed life, the thallus may be damaged or broken by natural factors (as strong waves, grazing by animals, etc.) or by human activity like the farming of economically important species. Healing is generally rapid or efficient which could be accomplished in 30 minutes in coenocytic seaweeds as Caulerpa (Dreher el al., 1978) or within the second week in bigger thallus as in Eucheuma (Azanza-Corrales el al., 1988). Wound healing is then followed or overlaps with regeneration or replacement of parts of redifferentiation of older adjacent cells to wounded area. This healing and regenerative capacity have been widely exploited in the culture of the abovementioned plants where vegetative propagation is the main technique in their production.

4. LIFE HISTORY AND REPRODUCTION

In the life cycle of more advanced members of green, brown and red seaweeds, there is an alternation of two or three isomorphic (i.e. some morphology) or heteromorphic (different morphology) somatic generations. The sporophyte (2N) produces spore through meiotic division, the meiospores (N) develop into gametophyte (N) where gamete formation is mitotic. Fusion of gametes (N) produce zygote (2N) which developes into the sporophyte completing the cycle. In advanced members of red algae for example in Gracilaria, a third somatic generation, the carposporophyte (2N) is produced “inside” the female gametophyte (N) after fertilization of egg by spermatia from male gametophyte. The carposporophyte produces carpospores (2N) in carposporangia which are released and germinate into tetrasporophyte (2N) that produces tetraspores (N) through meiosis. The tetraspores in turn develop into either female or male gametophytes (N), hence, completing the plant's life history.

From the abovementioned and other previous discussions, it is clear that seaweeds can multiply or proliferate in the dimensions of time and space through asexual and sexual means. Asexual method could be by 1) vegetative regeneration from fragments produced naturally or artificially, or 2) production of non-motile or motile spores produced in structures called sporangia. The former is called aplanospore produced in aplanosporangium and the latter is called zoospore formed in zoosporangia. Sexual reproduction is the fusion of gametes produced from simple or differentiated gametangia where in the latter, male gamete is produced from an antheridium while the female gamete from the oogonium. In the more advanced form of red and brown algae, fertile areas may be distinguished on the surfaces of the thalli. Spermatia (male gametes) may be aggregated in cavities called conceptacles, while tetrasporangia and/or female, reproductive structures may form distinct aggregations called sorus(i).

In some, specialized branches of spore production are called “receptacles” while in others portion of some branches are converted to fertile structures called stichidium (Trono and Fortes, 1988). Stalked or sessile cystocarps which contain the carposporophyte covered by a pericarp are formed on the surfaces of female gametophytes of red seaweeds as Eucheuma and Gracilaria. In Japan where seaweed culture is probably most developed, nets for Porphyra, Laminaria and Monostroma are seeded with spores indoor or in the laboratory. When the seedlings reach appropriate size and during appropriate time, the nets are transferred to the culture sites.

5. ECONOMIC IMPORTANCE OF SEAWEEDS

Man has a long history of seaweed utilization as direct sources of food, fodder, fertilizer and medicine. Various industries have used phycocolloids and other materials extracted from seaweeds for many purposes. World seaweed utilization has been reviewed by Levring et. al. (1969), Chapman (1970) and Bonotto (1976) as reported by Dawes (1981) who cited the brown and red seaweeds as the most dominant algae useful to man.

The following review of economic importance of seaweeds has been digested primarily from Dawes (1981) and Trono and Fortes (1988).

5.1 As direct source of food

Japan, China, Philippines, Korea and other Asian countries and Hawaii consume sea-weeds directly as food. They are mostly harvested from natural populations but mariculture of important species have been practiced specially in the first three mentioned countries. The species sold almost daily in the Philippines particularly in wet markets in Metro Manila are Caulerpa lentilifera, C. racemosa, Eucheuma alvarezii, E. denticulatum and Gracilaria verrucosa. Porphyra or “Nori” is a regular part of daily Japanese meal. The browns Laminaria and Alaria are also popular food items in Japan and Korea. Presently, the most expensive edible seaweed in Japan is Monostroma (Azanza-Corrales, personal communication). It is also farmed like the previously mentioned seaweeds but “Nori” remains the most extensively cultured.

5.2 Uses in medicine

Seaweeds have been variously utilized as medicinal herbs. Early Roman soldiers have used species to heal wounds, burns and rashes. Goiter and other internal disorders have been treated or prevented with sea-weeds by Chinese and Japanese. Agarophytes and carrageenophytes are good laxatives (Calompong, 1981). Digenea simplex has been reported to be a good vermifuge (Trono, 1973). Processed materials from seaweeds that are used in medicine and related areas are considered in item 5.4.

5.3 As fertilizer, fodder and fuel

Aqueous extracts mostly from brown seaweeds have been used commercially for agricultural purposes (Stephenson, 1974; Montano and Tupaz, 1988). Fertilizers from seaweeds result to increased crop yield probably due to the presence of growth promoting hormones (Bentley-Mowat, 1963). Other beneficial effects include increased resistance of crop to fungal and insect pests and increase water holding capacity of the soil (Mathieson, 1967). In Europe, seaweeds are dried and grounded to produce meals for animals. Macrocystis, Sargassum and Gracilaria are sources of fuel (menthane), production of which is a new-venture especially in the United States.

5.4 Sources of phycocolloids

Polysaccharides extracted from seaweeds (especially reds and browns) that can form colloidal or gel systems in water are called phycocolloids. Alginic acid is a polymer of D-mannuronic and L-guluronic acids and are derived from brown seaweeds. Alginates are used as emulsifier and stabilizers in the textile, paper, paint and food industries. They have been used to make surgical threads and whole blood substitutes for emergency transfusion. Half of the -entire world production of alginic acid comes from the harvesting of Laminaria in the North Atlantic. Other sources are Eclonia and Sargassum in the Pacific and Indian Oceans. Agar which chemically consists of agarose and agaropectin is a strong gelling phycocolloid mostly extracted from Gracilaria, Gelidium, Gelidiella and Pterocladia. The better quality agar is used as medium for culture of microbiological specimens. The food industry use them as protective gels in canned meat and stabilizers in many bakery products. They are also used in the sizing of fabrics, water proofing of paper and cloth and/or clarifying agent in the manufacture of wines, beers and coffee.

Carrageenan is a more sulfated (20–-50 percent galactan) compound compared to agar which has lesser degree of sulfation (less than 5 percent). Presently, there are five major forms (k,,λ,,μ,λ, i) of carrageenan already known. They vary in the levels of sulfation and the ratios of galactose to 3,6 anhydrogalactose. Carrageenan is extracted from members of Gigartinales, wherein the different forms are distributed between the diploid and haploid phases. In Chondrus, Gigartina and Iridaea, K-carrageenan is found in the haploid plant and carrageenan in the diploid plant. Eucheuma denliculatum contains only K-carrageenan while E. isiforme, E. alvarezii and E. uncinatum carrageenan only. This phycocolloid is used mainly in dairy products because of its stabilizing effects with milk proteins. It is also useful in the production of toothpaste, diet foods, soups and confections. Other products with carrageenan as suspending or gelling agent are those from the cosmetic, paint and pharmaceutical industries.

Trono and Fortes (1988) report that “out of the total world production of 650 000 mt of seaweed in 1980, about 270 000 mt were used in the manufacture of phycocolloids, the rest were utilized as food in Asia. The Philippines contributed 84 percent of total world supply of carrageenan, Republic of Korea produced 62 percent of total raw materials for agar while 70 percent of materials for alginate production were from European countries, the United States and Canada”.

Seaweeds, therefore, are very important not only for their biological roles in the marine environment but also for the economic benefits that they directly provide man.

¹ A lecture presented during the ASEAN/UNDP/FAO Regional Small-Scale Coastal Fisheries Development Project and Seafarming Development and Demonstration Project (Joint Training Programme), University of the Philippines, Diliman, Quezon City, May 2–21,1988.

² Assistant Professor, Marine Science Institute, University of the Philippines, Diliman, Quezon City, Philippines.

REFERENCES

Azanza-Corrales. 1979 The reproductive biology of the Gracilaria species of Manila Bay, Philippines. M.S. Thesis. University of the Philippines, Diliman, Quezon City.

Azanza-Corrales. (unpubl.) 1987 Annual report submitted to PCARRD on the project: Reproductive biology of Eucheuma species in Danajon Reef, Northern Bohol.

Azanza-Corrales, R.A., C.J. Dawes and S. Chan. 1988 Wound healing in Eucheuma alvarezii var. tambalang Doty in laboratory culture (in press).

Bentley-Mowat, J.A. 1963 Auxins and gibberellins in marine algae. Proc. Int. Seaweed Symp. 4:352 (as cited by Montano and Tupaz, 1988).

Bonotto, S. 1976 Cultivation of plants. Multicellular plants. In: Kinne, O. (ed). Marine ecology Vol. 3. Cultivation Part I. Wiley, New York.

Calompong, H.P. 1981 Economically important benthic marine algae in the Central Visayas, Philippines. Silliman Journal, 28:143–148.

Chapman, V.J. 1970 Seaweeds and their uses. Second edition. Methuen, London.

Dawes, C.J. 1966 A light and electron microscope study of cell walls II. Chlorophyta. Ohio J. Sci. 66:317–326.

Dawes, C.J. 1981 Marine botany. John Wiley and and Sons, New York, Brisbane, Toronto, Singapore.

Dawes, C.J., F.M. Scott and E. Bomler. 1961 A light and electron microscope study of algal cell walls. I. Rhodophyta and Phaeophyta. Amer. J. Bot. 48:925–932.

Dreher, T.B. Grant and R. Wetherbee. 1978 The wound response in the siphonous alga, Caulerpa simpliscula C. Ag. Fine structure and cytology. Protoplasma. 96: 198–203.

Haug, A. 1961 The affinity of some divalent metals to different types of alginates. Acta. Chem. Scand. 15:1794–1795 (as cited by Lobban et al., 1985).

Jacobs, W.P. 1985 Are angiosperm hormones present in and used as hormones by algae? In: Bopp, M. (ed.) Plant growth substances. Proc. 12th Int. Conf. Plant Growth Substances. New York: Springes Verlag, 1986.

Levring, T., H.A. Hoppe and O. Schmid. 1969 Marine algae. A survey of research and utilization. Cram, de Gruyter, Hamburg.

Lobban, C.S., P.J. Harrison, M.J. Duncan. 1985 The physiological ecology of seaweeds. University Press, Cambridge.

Mathieson, A.C. 1967 Seaweed — a growing industry. Pacific Search, Seattle, Washington (as cited by Dawes, 1981).

Montano, N. and L.M. Tupaz. 1987 Growth response of some plants to treatment with aqueous extracts from Sargassum polycystum and Hydroclathrus clathratus at varying levels. Phil. J. Sci. Monograph 17:11–22.

Morris, I. 1967 An introduction to the algae. Hutchinson, London.

Stephenson, W.A. 1974 Seaweeds in agriculture and horticulture. Mexico, USA (as cited by Tupaz and Montano, 1987).

Trainor, F.R. 1978 Introductory phycology. Wiley, New York.

Trono, G.C., Jr. 1973 Seaweeds: One of the important marine natural resources of the Philippines. pp. 28–50. In: G.T. Velasquez Lecture Series. Nat. Res. Council Philipp. Publ.

Trono, .G.C., Jr. and Ganzon-Fortes. 1988 Philippine Seaweeds Technology and Livelihood Resource Center. National Book Store, Inc. Manila.

Tupaz, L.M. and N.E. Montano. 1987 Effects of 1987 aqueous alkaline extracts from Philip-pine seaweeds as a foliar spray on crops. Phil. J. Sci. Mon. 17:29–36.

ANNEX A

Simple Artificial Key to the Four Divisions of Seaweeds

Table 1. General features of the four seaweed divisions

* Container of photosynthetic pigment

Practicum 1
INTRODUCTION TO THE FOUR SEAWEED DIVISIONS

by

Rhodora Azanza-Corrales

Taxonomy deals with the identification of plants (or animals) using data and information from their morphology, anatomy, physiology, genetics and biochemistry. It involves the classification or ranking (e.g., Division, Class, Family, etc.) of plants (seaweeds in this case) on the basis of their similarities and dissimilarities. Nomenclature, another aspect of taxonomy is the system of naming organisms.

This exercise will deal primarily on the classification of seaweeds at the Division level. It serves as an introduction to other practical work (i.e. identification of sea-weeds) by familiarizing the students with their morphological characters. Pressed and herbarium specimens of the more common representatives of the four divisions will be studied taking note specially of their root-like, stem-like and leaf-like structures. This will be useful in the recognition, collection and identification of these specimens.

As emphasized earlier in the lecture, the four seaweed divisions (Cyanophyta, Chlorophyta, Phaeophyta and Rhodophyta) are recognized based on their pigmentation, food reserve, cell wall composition and flagellation. To verify one's classification of an unknown or unfamiliar specimen, some simple biochemical tests (Hunt, 1978) could be employed.

For the guidance of the trainees, the following general characteristics of the four divisions have been included:

1. Cyanophyta (Blue-green algae)

Represented by bluish green to brownish, reddish or almost black-colored films or spongy tufts on intertidal rocks, other substrates as other seaweeds, the group has mainly freshwater and terrestrial forms. The marine members are mostly coccoid or filamentous forms of different sizes of colonies. They have lesser state of organization both at the cellular and organismic levels. Their pigments (chlorophylls, phycocyanin and phycoerythrin) are found in the cytoplasmic matrix and not in special containers called plastids. This feature can be verified even with the use of a light microscope. Reproduction is achieved by asexual method only, i.e., by fission, spore formation or fragmentation.

The members are found mixed with other seaweeds. In certain months of the year, their over-growth has become a problem in some seaweed farms where they compete for light, space, etc. with the crop. Lyngbya majuscula (Trono, 1981 unpubl.) is a common “pest” in Eucheuma farms where they form tufts on nets, posts or on crops themselves.

2. Chlorophyta (Green algae)

Most green algae are found in the fresh-water and terrestrial habitats. There are only a few truly marine representatives. They are bright green to grass green in color due to the predominance of chlorophylls (a and b) over the other pigments. Plastids which are special containers of photosynthetic pigments are ovoid to spherical or assume various shapes. These chloroplasts can be made visible with light microscopy. Photosynthetic reserves in the green algae are stored as starch. Cell wall is made up basically of cellulose with calcification in the same genera.

The group is represented in the marine environment by microscopic, unicellular or macroscopic coenocytic to multicellular forms. The thalli vary from simple free filaments to definitely shaped forms with distinct blade, stipe and holdfast. The leaflike structure or blade may be a thin expanded structure as in Ulva, or pinnate as in some Caulerpa species or assume various forms. Other members may be highly calcified as Halimeda.

Reproduction in this group are sexual and asexual by formation of flagellated or non-flagellated spores. Fragmentation of thalli that leads to their regeneration is a means of vegetative multiplication which is utilized in the farming, for example of' Caulerpa.

Certain species of Ulva, Monostroma, Caulerpa and Codium are being utilized as food in the Philippines and other Asian countries.

3. Phaeophyta (Brown algae)

Almost all the members of Phaeophyta are marine forms. Major pigments found are chlorophylls (a and c) and fucoxanthin, a special type of xanthophyll which gives the algae the brown coloration. Plastids are present in their cells whose walls are made up of an inner layer of cellulose and an outer layer of algin. Stored carbohydrate reserves are principally laminarin and mannitol.

There are simple freely-branching filamentous representatives. Many genera form macroscopic highly differentiated thallus. Distinct blades, stipe, holdfasts are exhibited by the Laminariales and Fucales or giant kelps (like Laminaria, Eisennia, Eclonia and Macrocystis. These are found only in the temperate areas where they form seaweed forests that serve as habitats of other marine organisms. The beginning of anatomical differentiation or formation of a less differentiated vascular tissue has been observed in the kelps.

In the Philippines as in many other tropical waters, several species of Sargassum, Turbinaria Padina and Dictyota form the major component of the reef flora. The genus Sargassum which is distributed widely from the tropical to temperate areas, forms extensive vegetation or “beds” which are habitats for marine animals specially fishes.

Reproduction in the group is both sexual and asexual. Motile reproductive cells are laterally biflagellated except in Dictyotales. Vegetative propagation through thalli fragmentation may occur or formation and abscission of special reproductive structure called propagules may also be undertaken.

4. Rhodophyta (Red algae)

Except for a few species, the members of this group are mostly marine forms. Their color is variable from reddish-brown to reddish-green because of variation in the amount of pigments (chlorophylls and the phycobillins-phycoerythrin and phycocyanin). This phenomenon called “chromatic adaptation” is the plant's adjustment to available light quality (wavelength) and/or intensity (Lobban, 1985). The chloroplast in the red algae are generally discoid. Food reserve is floridean starch. The cell wall is made up of cellulose together with agar or carrageenan. Many red seaweed genera are economically important because of their phycocolloid content. Common sources of several types of carrageenan are Eucheuma and Chondrus while Gracilaria, Gelidiella and Gelidium provide varying quality of agar.

The reds represent the most complicated life history and reproduction among the algae. Spores whether asexual or sexual are non-flagellated. Vegetative reproduction through regeneration of fragmented thalli is quite common and widely utilized in the farming of certain species of Eucheuma and Gracilaria. The three life phases in the life history of most red algae are: 1) sexual phase consisting of male and female gametophyte, 2) the asexual phase — the carposporophytes attached to. the female plant producing carpospores, and 3) the other asexual phase tetrasphorophyte producing tetraspores.

REFERENCES

Dawes, C.J. 1981 Marine botany. John Wiley and Sons, New York, Brisbane, Toronto, Singapore.

Hunt, J.W. 1978 Algal biochemical tricks and classification. The American biology teacher. 40 (9):528–531.

Lobban, C.S., P.J. Harrison, M.J. Duncan. 1985 The physiological ecology of seaweeds. University Press, Cambridge.

Ogawa, H. 1987 (unpubl.). Marine botany. Lecture hand-out, training in marine ranching, Kochi University, Kochiken, 40 mimeog. pp.

Trono, G.C., Jr. 1981 (unpubl.). The four major divisions of seaweed. Lecture hand-out. 3 mimeog. pp.

Trono, G.C., Jr. and E. Ganzon-Fortes. 1988 Philippine seaweeds. Technology and Livelihood Resource Center. National Bookstore, Inc. Manila.

Lecture 5 and Practicum 2
HOW TO IDENTIFY SEAWEEDS: USE OF DICHOTOMOUS KEYS¹

by

Edna T. Ganzon-Fortes²

As earlier mentioned, only through the practice of handling and distinguishing the seaweeds as they appear in nature or as pressed or preserved specimen can one develop the ease of identifying them.

For beginners, it is best to familiarize oneself with pressed herbarium specimens first before going to the field to collect fresh materials. In identifying a particular sea-weed species, the use of dichotomous keys is most useful because most seaweed literature provide it. However, seldom can one find a dichotomous key which include all seaweed groups or divisions. Most often, dichotomous keys are provided for only one division (i.e., one for Chlorophyta, one for Phaeophyta, one for Rhodophyta); and usually, keys are provided for major generic groups (e.g., a key to the Halimeda group, or Caulerpa or Laurencia, etc.). Therefore, before using a dichotomous key it would always require the identification of the division to which a particular species belong.

Especially when fresh, color may serve as the most convenient character to consider in identifying the particular division to which a seaweed species may belong. The green seaweeds (Chlorophyta) are almost grass green, although some species may be yellow-green or brownish-green. The brown seaweeds (Phaeophyta) are usually light to dark brown, yellow-brown, brownish-red, orange-brown but others may be bluish-green. Seaweeds that are colored red or purple, even in part, almost always belong to Rhodophyta. Some red species, however, may be colored brownish-red, or they may become yellow-brown, yellow-orange, or green in bright sunlight. In cases when group classification becomes difficult a simple biochemical test may be of help. To distinguish some reddish-brown or brownish-red seaweeds apart, immerse them in hot water maintained at 65 °C for a few minutes. Most brown seaweeds will turn green in 120 seconds but most red seaweeds will not turn green in 240 seconds. This is so because the hot water (65°C) dissociates the brown fucoxanthin pigments masking the chlorophylls, thus, allowing the green color to be observed. But in most seaweeds, the biliproteins (r-phycoerythrin) do not dissociate at this temperature, thus, retaining its color. A few red species, however, such as Gracilaria do turn green when immersed at 75 °C water as one will notice when they are blanched as required in certain recipes.

In our laboratory session, you will be given a set of dried seaweed materials to identify using dichotomous keys. These keys are only applicable to the species included in this exercise. They use morphological characters or traits that describe a particular genus or species to “split” or differentiate it/them from the other species or groups of species. For example:

¹ Delivered by Dr. Romeo Modelo, Associate Professor, College of Arts and Sciences, De la Salle University, Taft Avenue, Manila.

² Senior Research Assistant, Marine Science Institute, College of Science, University of the Philippines, Diliman, Quezon City.

Key to the genera of Rhodophyta

Look at the specimen and observe the presence or absence of the morphological character described which is calcification*.

* A seaweed is calcified when it is hard, brittle, or has chalky texture. To be sure, simply put a few drops of 10 percent Hydrochloric acid (HC1) to a very small portion of the thallus. If rapid bubbling results, this indicates the presence of calcium carbonate.

If the specimen is calcified, then proceed to number 2; if not calcified, then proceed to number 5.

Look at the specimen again and observe its habit (general form). If it is rock-like, then it might be Lithothamnium. If the characters described fit your specimen, then it is it. But if it does not, then it might be a different species. On the other hand, if your specimen forms free branches, then proceed to number 3 of the dichotomous key; and so on until you arrive at the identity of the species in question.

Just be sure to confirm the identity of the species by checking if its morphological characteristics tally with the description of the species provided in the taxonomic hand-outs.

Take note that a scientific name is given to each specimen. This consists of two names, hence, a binomial — the first is the generic name (genus) and the second is the specific name (species). The first letter of the generic name is capitalized while the specific name is written in small letters, and both are italicized or underlined.

Dichotomous Keys

* ligule — membranous appendage projecting from the summit of the leaf sheath.

Lecture 6 and Practicum 7
INVENTORY AND ASSESSMENT OF ECONOMICALLY IMPORTANT SEAWEED STOCKS

By

Miguel D. Fortes¹

1. ECONOMIC SEAWEEDS IN THEIR NATURAL ENVIRONMENT

In terms of gross potential use and production, the Asia-Pacific region is one of the richest source of' natural seaweed products in the world. Such taxonomic diversity results directly from the varied conditions which are generated by equally varied topographical features such as deeply penetrating coves, coral and volcanic islands surrounded by wide, gently sloping reef flats, shallow continental shelves, and the enormous length of the total coastline. In addition, the numerous islands divide the waters into different seas connected by channels, passages and straits, making possible differential distribution of nutrients and compaction and composition of the substrate. These features ensure the constant availability of requirements that favor optimal relief for growth and development of the seaweeds.

The ecological factors that affect the biology of seaweeds in marine tropical waters may be, as Doty (1946) mentioned, primary or secondary. Primary factors are major phenomena, like monsoons and tides, observable as large-scale changes in the earth's surface, exerting their effects on considerably large areas and influencing a number of requirements of the seaweeds. The secondary factors, on the other hand, are those like temperature, light and grazing which are more limited and specific in their effects, generally subject to the fluctuations in the primary factors. In nature, however, these latter factor cannot (and should not) be isolated from one another because their effects are known to be interactive. The growth of a seaweed is more the resultant effect of several factors acting together, either synergistically or antagonistically, in the multidimensional niche of that species. If attempts are made to isolate the effects of individual factors, these are made for no other reason that a consideration of practicality and expense. For the purpose of this training/workshop, the latter view is adopted in the monitoring of the effects of selected field parameters on the performance of seaweeds.

2. NON-SCIENTIFIC AND SCIENTIFIC SAMPLING

Much of our knowledge on seaweed research is based to a very large extent, on samples. An administrator accustomed to dealing with complete censuses as bases of policies is suspicious of samples and is reluctant to use them. His choice of a farming technique is often determined by the “impressions” gathered from few encounters he has had with the technique in the course of a few years. He would differ from one who devotes 20 years to “trial-and-error” methods, “feeling” the best possible method for optimum seaweed production. But in a real sense, the two differ in that the former bases his conclusions on a much smaller sample of experience. In science and in human affairs alike, often we lack the resources in order to take a complete study of the phenomena that might advance our knowledge. This is the primary reason why investigators resort to gathering samples.

Non-scientific approaches to ecological studies may be in the form of:

1. a guess;

2. reliance on previous experience and/or memory;

3. the use of logic or common sense;

4. making “spot checks” and “judgment” surveys; and

5. taking a 100 percent survey.

Unfortunately, all these approaches are usually very biased even though not intentionally so. If sufficient data from previous experience or originally gathered by some-one else is available, it may be used as the basis for decision-making. But often, this is not so easy to secure, or if readily available, insufficient for the purpose. Thus, the need arises to collect primary or new data.

Values reported that “spot checks” may be accurate but one cannot be assured that the conclusions drawn from them are valid and reliable. It is risky when used as a basis for making programme-management decisions. With 100 percent surveys, their costs are prohibitive, the actual surveys very time-consuming and they are often physically impossible to conduct.

Scientific sampling is “..... the use of efficient and effective systematic methods of collecting, interpreting and presenting data in a quantitative manner to facilitate understanding”. With these methods, bias inherent in the non-scientific techniques can be appreciably eliminated and the probability of being correct (or incorrect) ascertained. The principal advantages of scientific sampling as compared with complete enumeration in ecological studies are as follows:

1. Subjective and personal bias in the overall methodology is minimized;

2. Inasmuch as the conclusions will be based on just a few samples, precise quantitative statements can be made regarding how these samples closely reflect the whole population from where they were drawn;

3. The probability of being correct or incorrect can be estimated;

4. Since scientific sampling can give smallest number of samples needed to reflect the characteristics of a population, the method becomes more economical, efficient and effective; and

5. Compared to 100 percent survey, scientific methods are the more accurate and practical because there are many different sources of error in any enumeration of large amount of data. Hence, the smaller (but the more carefully controlled) the sample, the less chances of making mistakes.

3. SOME GENERAL GUIDELINES IN CONDUCTING A SCIENTIFIC FIELD STUDY

3.1 Clarification of objectives

It is often the case that your head office just wants “to know something about” or to be kept informed on the status of key areas in the project. There is really no “problem” and the request for you to study an area usually comes in the form of ambiguous formulae, focused on some observed details that seem to bother management. Get your guidance clear on what you are to study and once the objectives have been definitely stated, the need for the study becomes clearer.

The questions to be answered include: Why does management want to study? How important does the head office consider the need for answers? How accurate do the results need to be? When does management want the results? What is the budget limitation of the study?

3.2 Planning and organizing the study

There are many factors to consider in planning and organizing the survey. However, these can be categorized under two general headings, namely, administrative and technical. A serious consideration of funds, staff, equipment and administrative coordination is necessary before you go any further. Technically, once the problem is understood, formulate hypotheses to serve as possible explanations for the phenomenon to be encountered. This will lead to the right kinds of questions to be asked in order to resolve which of the hypotheses are correct.

Sometimes, questionnaires are important. The design and format of such materials are very significant in the accuracy in recording data. Master lists and a working schedule must be made available in order to complete the work in time for management's use. Also, an appropriate sample size must be determined as this will limit your time, money and personnel.

3.3 Selecting a sample

In sampling, one must know exactly the natural entity to be sampled. For example, if we obtain a collection of seaweeds from within a 0.25 m² plot, we must be aware that we have collected only a fraction of the entire vegetation. No single sampling technique can possibly give all the data required of a natural population or community. A given procedure can be best applicable only to certain species or group of species and not to others. This is the reason why the entity to be sampled must first be defined.

The population to be sampled (the sample population) should coincide with the population about which information is wanted (the target population). Conclusion drawn from the sample apply to the larger population.

3.4 Selecting a sampling procedure

There are several approved methods for drawing samples from a population, each of which has certain advantages depending upon the specific circumstances. If such item in the population is considered to have “equal importance” or where every point in that area is exactly like every other, you can perform either a SIMPLE or a SYSTEMATIC SAMPLING, the latter, useful especially if your population is arranged or lined up or along an environmental gradient. If on the other hand you know that the characteristics of the items in the population differ markedly, and it is possible to classify them you might want to select samples from each of these groupings in order to improve the validity of the survey. This more sophisticated approach is known as STRATIFIED SAMPLING. Finally, as plants may occur in clusters, it is possible to choose a number of clusters at random and measure the particular variable being studied on each of the units or individuals in the cluster. This method is called CLUSTER SAMPLING. Due probably to difficulties in field travel in some situations and/or in order to reduce travel time and cost, this technique may be the only practical means available to conduct the study.

The above sampling methods usually involve plots or quadrats of measured area. Hence, the results obtained using them are likely to be a function of the plot size. In plotless sampling, there is the advantage of not having to demarcate plots of a certain size or shape (hence, less laborious). The most popular of the plotless techniques are the POINT-QUARTER (QUADRAT) and WANDERING-QUARTER methods.

3.5 Conducting the study

Once the ecological entity has been defined and the sampling procedure chosen, one can do the actual sampling. How to obtain representative samples of the defined population is the next problem. Normally, statistical samples should be taken at random, in which case, you assume that each item in the population has an equal chance of being “picked” and that the occurrence of one individual in a sample in no way influences the inclusion of another. A sampling method is biased if it tends to underestimate a characteristic of the population or a community.

In a taxonomic sense, representative samples are those complete in parts (i.e. sample seaweeds to be collected should have fronds, stipes and holdfasts). Only such whole plants can facilitate correct and proper identification.

A single measurement is generally not enough to be used as basis of conclusions about an ecological characteristic. Replicates should be taken and from them, the mean of the statistical population can be estimated and the amount of error, determined.

In some instances, only portions of ecological samples or subsamples can be taken in the laboratory and studied. So long as the subsamples are taken randomly from the sample, they reflect the characteristics of the entire sample.

3.5.1 Quantitative assessment of abundance and production

Obviously, a large amount of error is inherent in using subjective means of describing vegetation. To at least minimize the error, ecologists resort to quantitative measures, with statistical considerations. Although unavoidably time-consuming, these methods give workers a more realistic picture of the structure and dynamics of a vegetation.

a) Density (D) — This is the count of the number of individuals within a series of randomly distributed sample areas (quadrats or plots). The method allows comparison of different areas and different species and is an absolute measure of abundance of the plants. Its disadvantage lies in the large amount of time involved in counting the individuals.

While density (often called crude or absolute density) is the number of organisms per unit total space or volume, much of the area or volume may not actually be colonized by the population. It is, therefore, more meaningful to speak of the number of organisms per unit of habitable space (specific or ecological density).

Often, it is more important to know whether a population is changing than to know its size at any one moment. In comparative studies, one generally wants to know the number of individuals relative to other populations. In such cases, relative species density, RD, is useful. It is the total number of individuals of a species expressed as a proportion (or percentage) of the total number of individuals of all species present:

b) Frequency (F) — Frequency is a measure of the chance of finding a species with any one throw of a quadrat in a given area. Thus, if Gracilaria has a frequency of 0.1, then it should occur once in every 10 quadrats examined:

The method is done simply by noting whether a species is present or absent in a series of randomly placed quadrats (or in the smaller squares within a quadrat). For example, if 43 quadrats out of a total of 90 contain Gracilaria, the frequency is 43/90 = 0.48. This is the same as saying that the probability of finding the seaweed in the sample is 48 percent.

Greig-Smith (1975) proposed two convenient forms of frequency, namely, shoot and rooted frequency. The former considers a species as “present” only when any part of the plant thallus overlaps into the quadrat. The latter measure considers a species as “present” when it is actually rooted within the sampled area.

The only advantage of frequency as a measure of abundance lies in the ease and rapidity with which an area can be sampled. Values obtained using this method are dependent on the size of the quadrat used, and the size and spatial distribution of the individuals inside the area sampled.

The relative frequency, Rf, is the frequency of a given species expressed as a proportion of the sum of the frequencies for all the species:

c) Cover (C) — This is the proportion of the ground or the substratum occupied by the individuals or parts of the individuals of the species under consideration. It is an estimate of the area covered by the given species, expressed as a percentage of the total area, measured usually by taking a number of points from the sample area and determining at those points which species, if any, is covering the surface of the substratum. As this method involves visual estimates, it is prone to personal bias, as was discussed in relation to frequency ratings;

The relative cover (RC) is the cover for a species expressed as a proportion of the total cover of all the species.

As a rough and overall estimate of the influence or importance of a plant species in the community, the importance value (IV), may be useful:

IV_i = RD_i + RF_i + RC_i

Saito and Atobe (1970) utilized a more refined method in the estimate of seaweed frequency and cover. The method makes use of a 0.25 m² (50 × 50 cm) quadrat, divided into 25 small squares, each measuring 10 × 10 cm². This quadrat size of 0.25 m² was chosen by first comparing it with bigger quadrats, i.e., 0.5 m², 1.0 m², the values obtained fitted in a species-area curve.

The frequency value (F) of each algal species is determined by counting the number of small squares (10 × 10 cm²) the species appears in the quadrat (qn), and this will be computed in percent using the formula:

Calculation of the species coverage (C) is done by assigning numbers to indicate degree of dominance or cover. The numbers 1, 2, 3, 4 and 5 are used as indices of species coverage in one small square of the quadrat as observed in the field. Each number has a corresponding percentage value when computed in the laboratory as tabulated below:

The percent coverage (C) of each species is computed as follows:

where qn, is the number of small squares (10 × 10 cm areas) recorded as having a certain “c/25” cover (see above table occupied by the species.

Evaluation of the similarity or dissimilarity of the algal communities in two study stations is based on Frequency Index Community Coefficient (FICC) values computed as:

The advantage of the above formula over those of Jaccard's (CC_J) and Sorensen's (CCs) Community Coefficient formulae (cited by Brower and Zar, 1977) is that, not only are the total number of maldistributed and common species accounted for, but also their density as they occur in the field as measured in terms of their frequency. In other words, FICC involves quantification of the maldistributed and common algal species, whereas, CC_J and CCs account only for the number of maldistributed and common species without consideration of their density.

d) Standing crop biomass — This is the weight of existing species in a given area at any one time. Commonly, all the species within a plot are collected, sorted and dry-weighed. The result will give an estimate of the amount of matter produced by a species or a group of species in the area. Where there are large differences in the sizes of species present, standing crop biomass is an import-ant measure of “abundance”:

B = (D) (TW/n)

Biomass for non-discrete, creeping (hence, non-individually countable) species is simply their absolute weights.

For organisms which vary greatly in moisture content, biomass should be expressed as dry weight rather than fresh weight. Biomass expressed as ash-free dry weight, nitrogen, carbon, or caloric content is useful in cases where the organisms vary in the amount of inorganic skeletal material,

e) Growth rate (GR) — This is a measure of how well a species is growing in a given area. Measurements of growth rates in seaweeds depend on their modes of growth, i.e., for Ulva and Porphyra, it is best to measure the change in area of an initial portion of a frond because they both exhibit diffused growth; for Laminaria, which grows by means of an intercalary meristem, growth rate is determined by getting the difference in the length of the frond after some time interval:

f) Productivity (P)—This is the rate of organic matter production by organisms. In some cases, estimates of biomass may be useful to measure productivity:

Biomass is usually expressed as units of weight per area (or volume) of habitat, and productivity, as units of weight per unit area (or volume) per unit time. Hence, the turnover time is the number of time units (days, months, years) required to produce as much biomass as is present at the time of measuring the standing crop. .

3.5.2 Determination of other ecological parameters

From the above basic ecological measures, others can be determined to reflect some of the structural aspects of the community not explicit in density, frequency, or cover. Indices of species diversity, dominance and similarity of dissimilarity give better insights on the structure of the community in comparison with other communities or relative to a change in time. For example, the degree of influence of a fertilizer on the floral composition of a seaweed community may be assessed by monitoring the change in the diversity of the community. Physically-stressed habitats are generally less diverse than biologically-controlled ones.

a) Species diversity — Species diversity is a measure of the number of species (the* variety component) and the relative abundance of the individuals of each species (the evenness component). There are a number of diversity indices proposed, each one with its own defined usefulness depending upon the nature of the community in question. Some of the more popular ones are: Shannon-Wiener Index (H'), Brillouin's measure (H) and Simpson's (D).

b) Ecological dominance — This is a measure of the degree of control by a species or species groups of the energy flow and the environment of all the other species. A more popular index of dominance is given by Simpson (1949).

C = (n_i/N)²

c) Similarity/dissimilarity — Often after knowing the seaweed flora of two or more communities, you ask the question: How similar (or dissimilar) are the communities in terms of the species present? Or you may want to compare the species composition of the same community at two different times. In such instances, indices of similarity or dissimilarity may be useful:

(i) Jaccard's coefficient (CC_J):

(ii) Sorensen's coefficient (CCs):

where, in both (i) and (ii), c = number of species common to both communities S₁ and S₂.

The index of dissimilarity is 1 - CC_J or 1 - CCs

4. SOME SELECTED PHYSICO-CHEMICAL PARAMETERS

The particular condition that characterizes a natural habitat is the result of myriads of factors, interacting with one another to create an overall, highly specific and prevailing effect that maintains the ecological integrity of the ecosystem as a whole. These factors have . been conveniently classified as biological and physico-chemical factors. Biological factors are active, energy-requiring interrelations among the biotic components, exerting their effects directly on the species, populations, or communities themselves. It is often difficult to directly and immediately determine the degree of effect of these factors. Thus, grazing pressure, pests and diseases, and direct human impact are primarily biological in nature.

Physico-chemical factors, on the other hand, are abiotic factors in the environment that are directly or indirectly and immediately measurable using specific devices and instruments. Under natural conditions, it is impossible to isolate them and pinpoint separately their effects.

There are two important considerations in dealing with ecological factors: factor interaction and factor compensation. Factor interaction emphasizes the fact that “... high concentration or availability of some substance, or the action of some factor other than the minimum one, may modify the rate of utilization of the latter” (Odum, 1971). Sometimes organisms are able to substitute, in part at least, closely related substances for one that is deficient in the environment. Such factor compensation emphasizes the fact that organisms are not just “slaves” to the physico-chemical environment; they adapt themselves so as to reduce the limiting effects of the physical and chemical conditions of existence. Thus, seaweeds with wide geographical ranges almost always develop locally adapted populations (“ecotypes”) that have optima and limits of tolerance adjusted to local conditions.

Table 1 gives some ecologically and “operationally significant” factors (sensu Odum, 1971) which are known to influence the biological attributes important in the management of seaweed resources. The influence of each of these factors is the subject of another lecture in this course and need not be emphasized here. Their determinations in the field deserves some attention since one factor may give widely differing results depending upon the type of instrument used, the time and place of determination, and the purpose of the investigator. For comparison purposes, field methodologies have to be standardized and intercalibrated.

5. MONITORING: PURPOSE AND NATURE OF THE PROCESS

The primary purpose of the monitoring process is to gather data, adequate and accurate enough to be useful in the prediction and control of major trends in certain biological attributes for management purposes. Hence, monthly monitoring of the growth rate or biomass of natural stocks of the brown seaweed Sargassum aims to pinpoint the temporal and spatial peaks and troughs in its organic matter production, as well as those factors that have considerable influence On this attribute. The information generated could be the key in the prediction and control of future production trends in order to sustain yield at an optimum level.

To monitor an ecological factor is to regularly observe, determine and record the changes that occur in that factor as a result of heterogeneity in time and space. However, certain major requirements should first be satisfied before the process is undertaken.

1. The “operationally significant” factors should be known, i.e., those factors which most likely have considerable influence on the biological attribute in question;

2. Temporal and spatial changes, in those factors should be sufficiently covered within the predetermined intervals of operation;

3. The operations should be repeatable and can be carried through at least the time span of a complete life cycle or development of the species or community in question;

4. The data to be generated should come from sufficiently large sample sizes for statistical purposes; and

5. No major technical or administrative problems should be expected to seriously interfere in the course of the operation.

In the Philippines many research projects fail because these are poorly conceived. Their objectives while sound and clearly expressed are more often “sidetracked” at the completion of the project. The data gathered, when validated are unreliable, hence, risky when used as basis for policy decisions. The problem lies primarily in major defects in the monitoring process (if ever such process is made an integral part of the project objectives). The factors chosen for monitoring purposes are dictated either by the availability or type of instruments at hand, or by the literature which more often than not espouses techniques dismally unsuitable under local conditions. To compound the problem, the study intervals chosen, while scientific in intent, decidedly become a function of the irregular and delayed releases of the necessary support funds. The results are wide gaps in data unacceptable for statistical analysis and interpretation.

Baseline data that relate to the biology and ecology of target seaweed species for culture either do not exist, or are poorly known. This is due to the lack of directly relevant literature materials which remains as the major handicap in the conceptualization and implementation of the acceptable experimental design and procedure. Sample sizes and the chosen intervals along transects or through time periods are often arbitrary and dictated by convenience without regard to the natural structure along habitat gradients, seasonal dynamics of the vegetation, or much less, to statistical considerations.

6. SPECIFIC CONSIDERATIONS IN THE MONITORING OF THE SELECTED PARAMETERS

Serious technical, logistical and administrative considerations must be made before any monitoring activity is planned and implemented. These aspects of management have varying degrees of effects on the project objectives. Government agencies mandated to perform general livelihood tasks more often lack the specific technical expertise and the necessary library support to design efficient and acceptable monitoring activities. Their meager research funds, if there exist, are normally tied up with other unrelated office projects and it becomes virtually impossible to transfer funds for a project of lower priority rating. On the other hand, academic and private institutions whose substantial research funds are committed to a particular and specific purpose, enjoy the big advantage of focusing all efforts, time and the monetary allotment to that specific project. Hence, in these institutions, one finds adequate library acquisitions and the necessary equipment and facilities to even extend positively the project activities beyond those expected, and with much better reliable results. This problem varies from agency to agency, public or private, and it is beyond the scope and responsibility of the present training/workshop to deal lengthily with such administrative aspect.

Table 1 lists some biological attributes or parameters that are known to be significantly associated with seaweed culture or management objectives. These parameters are matrix-correlated with operationally significant biological, physical and chemical factors that are known to considerably influence the status of the parameters. The degree of effects of the factors are, for convenience, categorized into low (L), medium (M) and high (H). The degree of effect is low when it is short-term, localized, and does not cause a significant negative shift in the observed trend in the parameters; it is medium when the effect is medium-term, affecting a sufficiently large percentage of the total area or activity, and a degree change above or below its level causes a significant shift in the trend; the degree of effect of a factor is high when it affects negatively a very large percentage of the area or activity, causing a major adverse shift in the trends of the parameters.

Table 1. Matrix table emphasizing the degree of correlation between the biological attributes and some ecological factors of the coastal seaweed environment. L — low; M — Medium; H — high.

For exploratory management purposes, most of the factors that correlate with the biological parameters at the M-H and H levels should ideally be monitored. Monitoring of those factors that correlate at the L and L-M levels, on the other hand, may be postponed for a future date when conditions favor their inclusion in the monitoring process. For example, at an experimental farm of the red seaweed, Eucheuma, management would be better advised to monitor seedling density, biomass and seasonality as these parameters are affected by urchin or fish grazing, harvesting or “poaching” (direct human impacts), water temperature, salinity and movement, nutrients, tidal exposure, submersion and the possible inflow of toxic substances. On the other hand, if the purpose of management is simply to increase hectarage in a natural community, the factors to be considered in the monitoring process would principally be the direct influence of the activities of the inhabitants, water movement, tides and certain features of the substrate.

It should be noted that the degree of effect of the ecological factors may be species-specific and/or site-specific. More detailed studies are required to pinpoint the causal factors in the observed changes in the production and growth of local seaweeds. This could be done through both laboratory and field experiments. In the Philippines, it is a “rule of thumb” to utilize available foreign information that probably could be useful in the management of a related species.

Among the ecological factors, six emerge as decidedly the more important, as far as their effects on seaweeds under tropical conditions are concerned. These are: direct human impact, nutrients, water movement, light, tides and substrate. Unplanned or uncontrolled collection or harvest, damage wrought by plying boats and coastal development activities (e.g., marinas, ports) affect the seaweed communities not just through direct physical decimation or removal, but also the quality, quantity and availability of nutrients, water flow and circulation, and the amount of light available via increase turbidity and siltation. Tides have been mentioned earlier as a primary factor affecting the fertility of tropical coasts since their diurnal fluctuations affect most other factors in the marine environment. The rapidly increasing industrialization in the Philippines indicates that the shallow coastal portions where seaweeds abound will not in the years to come, improve its productivity in relation to the level where it is now. The prevailing wrong attitude of the people is such that the marine resources including seaweeds are viewed as inexhaustible, easily replaceable with the minimum time and effort. Compounded by their low income, these people turn to the sea as an alternative means to acquiring their basic necessities, but in the most destructive way.

There are other specific considerations associated with. the monitoring process. Basic to science, all activities must have controls. Regularly monitoring the effects of stipe cutting in the growth rate and biomass of Sargassum must, by comparative necessity, include a similar set of activities on uncut plants. Data generated in this way give useful information on the advantage or disadvantage of the introduced variable (i.e., cutting), the result inevitably becomes an index of profit or loss left for management decisions. Fortes (1981) emphasized the usefulness of describing habitats in terms of the biological composition and interactions, not in terms of the physico-chemical factors.

For initial field exploratory purposes, monthly or bimonthly sampling may be done, especially if one intends to follow the phenology and production potentials of seaweed species. But once information on the parameters are established, it is not always practical and much less scientific, to do sampling outside the natural phenological cycle of the species. Hence, if a species has a turnover time of 60 days, it would be advisable to sample once every two months. In addition, each country has its own set of meteorological conditions to which local seaweeds directly or indirectly respond physiologically, structurally or through differential species occurrence or composition. In the Philippines, the coastal parts of Regions I and III, and the western sections of Regions IV, IVA and VI belong to the First Climatic Type (Figure 1). These areas are characterized by two pronounced seasons, dry from November to April, and wet during the rest of the year. The north and eastern coasts of Region V, the eastern coast of Region VIII, northern Region X, and the entire eastern portion of Region XI belong to the Second Climatic Type. These areas are characterized by the absence of a dry season, with a very pronounced maximum rainfall from November to January. Coastal Aparri (Region II), Romblon, the eastern halves of Panay (Region VI) and Negros and Cebu (Region VII), eastern Palawan (Region IV), the mid-northern part of Region X, and western Zamboanga (Region IX), belong to the Third Climatic Type. These areas have relatively dry season from November to April and a wet season during the rest of the year. The eastern coasts of Region II, Mindoro and Quezon (Region IV), north-western Samar and western Leyte (Region VIII), northern Cebu and the whole of Bohol (Region VII), northwestern coasts of Region X, Cotabato, eastern Davao del Sur (Region XI), Pagadian, the southern islands of Region IX and the coastal portions of Region XII belong to the Fourth Climatic Type. These areas are characterized by rainfall that is more or less evenly distributed throughout the year.

Figure 1. Relative locations of the seagrass study stations in the Philippines

Hence, in terms of climatic types, factor-monitoring could also be location-specific. So long as the major seasons of a climatic zone, and the period (month) when they occur are known, management is well advised to monitor during months representing these seasons. Two but intensive samplings would be minimum for Pangil (Ilocos Norte), Bolinao (Pangasinan), Batangas, western part of Mindoro, the entire western Panay and Negros, and the entire stretch of north-eastern, northern, western and south-western Palawan. One sampling would be representative of the dry season (from November to April) and another, representative of the wet season (May to October). Field monitoring in the other parts of the country should be spread evenly throughout the year. Contingency alternative monitoring periods are required in the more northern parts of the country where the frequency of tropical cyclones is highest.

¹ Associate Professor of Marine Science, Marine Science Institute, College of Science, University of the Philippines, Diliman, Quezon City.