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One of the first challenges for those designing studies and protocols directed at global coastal systems is to determine (i) the factors driving the definition of the coastal area, and (ii) the selection and articulation of analytical frameworks needed to select critical indicators and assessment tools. Neither task is simple, straightforward or without the controversy of choosing among myriad options.

2.1 The coastal system

Defining the coastal system is an early and obvious task for any effort like the design of the Coastal GTOS Module. Nevertheless C-GTOS has not accepted one definition of the coastal zone. Rather it has reviewed the definitions and approaches adopted by potential users. The review has been summarized by categorizing users into three groups or hierarchical levels: multilateral environmental agreements, international organizations, and global/national assessment initiatives dealing with coastal issues. A range of definitions of the coastal area and ecosystems can be found in Table 2. Although these vary in extent and characteristics, four discrete approaches to defining coastal area can be derived. Those views can be categorized through descriptions of the coast from the perspective of:

Definitions of coastal areas and ecosystems used by international organizations and initiatives with coastal management mandates (direct quotes are shown in italics)


International initiatives with coastal mandates

Definitions of coastal areas or associated ecosystems and habitats

The United Nations Millennium Assessment (MA) is an international work programme designed to meet scientific information needs concerning the consequences of ecosystem change and available options for response. Documentation: MA (2003);

The Millennium Assessment reports on ecosystems and ecosystems services within reporting categories. The coastal zone is one of six reporting categories defined by (i) a central concept and (ii) boundary limits for mapping. Central Concept: interface between ocean and land, extending seawards to about the middle of the continental shelf and inland to include all areas strongly influenced by the proximity to the ocean. Boundary Limits for Mapping: area between 50 m below mean sea level and 50 m above the high tide level or extending landward to a distance 100 km from shore. Includes coral reefs, intertidal zones, estuaries, coastal aquaculture and sea grass communities. MA reporting categories are not mutually exclusive. For example, a wetland ecosystem in a coastal region may be examined both in the MA analysis of coastal systems as well as in its analysis of inland water systems. Some differentiation is made between the coastal zone and other adjacent reporting categories based on the definition of boundary limits for mapping. For example, the coastal zone has a shared boundary with boarding marine systems (> 50 m depth). Permanent inland waters of inland water systems are also separated spatially from respective coastal systems (permanent water bodies inland from the coastal zone).

The Ramsar Convention on Wetlands held in Ramsar, Iran, in 1971, covers all aspects of wetland conservation, recognizing wetlands' extreme importance for biodiversity conservation and the well-being of human communities. Documentation: Ramsar Convention on Wetlands (1971) and associated key documents (Articles 1.2 and 2.1);

The Ramsar definition of wetlands accounts for a wide variety of coastal habitats. The Ramsar Classification System for Wetland Type lists the following types of coastal wetlands: permanent shallow marine waters; marine subtidal aquatic beds; coral reefs; rocky marine shores; sand, shingle or pebble shores; estuarine waters; intertidal mud, sand or salt flats; intertidal marshes; intertidal forested wetlands; coastal brackish/saline lagoons; coastal freshwater lagoons, and karst and other subterranean hydrological systems. Under the original Convention on Wetlands, wetlands are described as: areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres... [Wetlands] may incorporate adjacent riparian and coastal zones, islands or bodies of marine water deeper than six metres at low tide lying within the wetland.

Agenda 21 was adopted at the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro, Brazil, in 1992. It is one of the key documents for integrated coastal area management and led the way for subsequent coastal area agreements and legal instruments. Documentation: UNCED (1992);

Chapter 17 includes seven major programme areas that relate to coastal areas and management, of which the first is integrated management and sustainable development of coastal areas, including Exclusive Economic Zones.


The United Nations Environment Programme (UNEP) is developing a module for the Assessment of the Coastal and Marine Environment (CME) as a contribution to the planned Global Marine Assessment (GMA). This contribution encompasses and is expanding upon existing assessment initiatives for the major coastal and marine ecosystems. Multiple other coastal-related initiatives have been or are being conducted, such as the programme on Integrated Coastal Area and River Basin Management (ICARM) relevant to the terrestrial coast. Documentation: UNEP (2004); UNEP/MAP/PAP (1999);

An exact definition and spatial extent is not specified for coastal habitats that are part of the CME assessment. Instead an adaptable approach is proposed to determine the scope, based on existing assessment methodologies: the geographical structure of the assessment has to be flexible and based on natural, political and institutional realities. Existing geographical and programmatic structure ... should be used where appropriate. The large variety of habitats in coastal waters is noted, including coastal wetlands, estuaries and deltas, mangrove, coastal reef and seagrass beds.

ICARM guidelines identify the area of concern as encompassing the catchment, the coastal zone and the nearshore coastal waters.... Four interacting zones are taken into consideration: coastal waters, the coastal strip, estuary, and the coastal plain.

The United Nations Education Scientific and Cultural Organization (UNESCO) has numerous coastal initiatives relating to coastal assessments. These take place primarily through the Intergovernmental Oceanographic Commission (IOC), which (as with many UN coastal initiatives) collaborates routinely with Small Island Developing States (SIDS). Integrated Coastal Area Management (ICAM) is one such programme, which is currently developing indicators for assessment of the coastal area. Documentation: UNESCO (2003a);

A recent guide to the use of indicators for ICAM states that catchment management deals with land usages in the coastal stream and river runoff areas for lagoons, bays and estuaries.

The Food and Agriculture Organization (FAO) of the United Nations has multiple initiatives that cover coastal areas, their management and the production of relevant guidelines, such as the Code of Conduct for Responsible Fisheries. Documentation: Scialabba (1998); FAO (1995);

The FAO ICAM guidelines state: an ICM programme embraces all of the coastal and upland areas, the uses of which can affect coastal waters and the resources therein, and extends seaward to include that part of the coastal ocean that can affect the land of the coastal zone. The ICM programme may also include the entire ocean area under national jurisdiction (Exclusive Economic Zone), over which national governments have stewardship responsibilities under both the Law of the Sea Convention and UNCED

The Coastal Ocean Observations Module of the Global Ocean Observing System (C-GOOS) has been developed with the goal of monitoring, assessing, and predicting the effects of natural variations and human activities on the marine environment and ecosystems of the coastal ocean. Documentation: UNESCO (2003c);

Coastal, as defined for use in the Coastal Module of GOOS, refers to regional mosaics of habitats including intertidal habitats (mangroves, marshes, mud flats, rocky shores, sandy beaches), semi-enclosed bodies of water (estuaries, sounds, bays, fjords, gulfs, seas), benthic habitats (coral reefs, sea grass beds, kelp forests, hard and soft bottoms) and the open waters of the coastal ocean to the seaward limits of the Exclusive Economic Zone (EEZ), i.e. from the head of the tidal waters to the outer limits of the EEZ. The definition of coastal zone is adopted from Nicholls and Small (2002): the land margin within 100 km of the coastline or less than 100 m above mean low tide, which ever comes first.


The International Geosphere-Biosphere Project's (IGBP) mission is to deliver scientific knowledge to help human societies develop in harmony with earth's environment. The mandate of
Land-Ocean Interactions in the Coastal Zone (LOICZ), as a core project of IGBP, is to address global change in coastal systems and to inform earth system sciences on the relevance of global change in coastal systems. Documentation: IGBP Secretariat (2004);

LOICZ includes in its statement of major goals the following reference to the costal zone and scales of activity: to provide a framework ... and to act as a means to focus on key issues concerning human activity and resource use in the coastal zone by applying the full water-continuum scale including the river catchments and the EEZ as spatial scales of major human interventions.

The Global International Waters Assessment (GIWA) assesses international waters and associated basins to provide information needed by the Global Environment Facility (GEF) for work in international waters. A GEF objective for this focus area is to serve primarily as a catalyst to the development of a more comprehensive, ecosystem-based approach to managing international waters and their drainage basins. Documentation: Pernetta and Mee (1998); UNEP (1999);

International waters and their drainage basins, which include coastal areas, are one of four priority areas identified by GEF and assessed by GIWA. These combined areas often include many different coastal habitats (comprising marine, coastal and freshwater areas, and surface waters as well as groundwaters). The main determining factor for this geographic delineation was the integrity of each unit in terms of encompassing the major causes and effects of environmental problems associated with each transboundary water area, whether river basin, groundwater, lake or sea. In many cases, a drainage area and associated marine basin (often a large marine ecosystem, LME) were the most appropriate units.

The World Conservation Union (IUCN), National Oceanic and Atmospheric Administration (NOAA) and other organizations that assist developing countries in implementing ecosystem-based strategies use Large Marine Ecosystem (LME) as the principal assessment and management units for coastal ocean resources. Documentation: Sherman and Duda (1999);

LMEs include multiple coastal habitats as they are regions of ocean space encompassing coastal areas from river basins and estuaries to the seaward boundary of continental shelves and the outer margins of the major current systems. They are relatively large regions... characterized by distinct bathymetry, hydrography, productivity, and tropically dependent populations.

Ultimately, C-GTOS products will need to be structured in the context of the users' definitions of the coast, taking into account the four common approaches identified for defining coastal areas. A general trend over time can be seen in the change of approaches for many types of organizations managing coastal areas (Table 2). Earlier definitions focused on geography and management units (e.g. EEZ and various ICAM guidelines). More recent coastal management initiatives have had a greater focus on ecosystem functionality and also include interaction with human use dynamics. The ecosystem approach has been endorsed by the Convention on Biological Diversity (CBD) and the Millennium Ecosystem Assessment (MA), and other current global assessments are consistent with this. The approaches presented here are not mutually exclusive. To meet user needs fully, C-GTOS does not define the coast in a single way. Rather, it attempts a strategic approach that highlights the need for understanding the diversity of views and the potential for diversity in user needs (see Section 1.4.1).

2.2 Frameworks of organization

Efforts to define the extent of the coastal area cannot be effectively conducted without the input and influence of associated analytical frameworks. These frameworks aid in both the precise determination of that extent, and critically in the understanding of the function and value of such areas. A review of needs in various coastal assessments led to a focus on four dominant frameworks. They connect most explicitly with the view of coastal areas and contribute most directly to the building of a linked network of programmes and practices as envisaged in Coastal GTOS.

These four frameworks will be developed in this section:

2.2.1 Driver-Pressure-State-Impacts-Response (DPSIR)

DPSIR highlights human components of the system, coupling socio-economics with environmental observations. DPSIR does not provide explicit recognition of the complexity of ecological interactions. The DPSIR framework provides a general view of the nature of large-scale influences on the state of the environment and on the need to understand and address consequential social impacts driven by environmental conditions. DPSIR serves as a tool to manage change based on clearly identified societal and environmental benefits. The constituents of the DSPIR framework are defined below and exemplified in a C-GTOS-relevant context in Table 3.

The DPSIR framework exemplified using population growth as a driver. Values are examples taken from northern Italy






Population growth

  • Increased water extraction (upstream)

  • Increased wastewater release (downstream)

  • Higher loading of pollutants

  • Deterioration of water quality

  • Changes in water level

  • Variations in river discharge, current velocity

  • Enhanced turbidity

  • Community changes

  • Pollution

  • Sediment accumulation

  • Reduced infiltration

  • Water conservation management

  • Implementation of wastewater treatment

Increase of 1000 inhabitants

  • Water extraction (150 litres per inhabitant)

  • Change in BOD1 (54 g BOD/ [inhabitant × day])

  • Groundwater level falls by 150 m3 per inhabitant

  • Coastal water receives 150 m3 × 54 kg BOD/ [inhabitant × day]

  • Change in landed value of local commercial fishing

  • Changes in recreational value to bathing beaches

  • Water savings (extraction falls from 150 to 100 litres per inhabitant)

  • Wastewater treatment leads to 80% uptake of BOD

  • BOD release decreases (100 × 54 × 0.2 g BOD/day)

1. BOD refers to biochemical oxygen demand, a measure of water quality and the amount of organic pollution

2.2.2 Inland - Coastal Zone - Ocean (ICZO) physical boundaries

The geographic framework clearly designates the coastal zone as the boundary region between continents and oceans or inland seas. The ICZO structure places C-GTOS into a broader context rather than helping to delineate its components. The coastal zone is the interfacial region between the inland and oceans. Both inland and ocean exert a direct influence on the coastal zone through the transfer of energy, material and information. Accordingly, the coastal zone is distinguished by having a strong gradient of parameters that can be either continental or oceanic in origin. By this reasoning, the inland and ocean boundaries are delineated by the limits of oceanic and continental influences, respectively. For C-GTOS purposes, the extent of the coastal zone is further described in section 4.1.

2.2.3 Human Systems - Ecological Systems - Delivery Systems (HSESDS)

Beyond these two more established frameworks, two additional views are presented as vehicles to focus on the dynamic interactions particularly prevalent in the coastal zone. The third framework focuses on three interactive components in the coastal zone, categorized as HSESDS. This triad is illustrated in Figure 2. Here, the concept of human systems refers to all aspects of societal impacts and activities in the coastal region. Two key considerations include land-use patterns and human population dynamics. Ecological systems comprise land cover and habitat, including both terrestrial and aquatic coastal environments. Delivery systems focus on the water cycle, with consideration of both delivery and quality. The delivery systems incorporate the materials (nutrients, sediments and pollutants), energy and information transferred. Moreover, atmospheric pathways must be included.

Whereas some issues of interest and concern may be largely contained within one system, others can arise due to the interactions between systems. The DPSIR approach can be readily incorporated to describe the relationships between the human and ecological systems. The strategies of international programmes can be included in this framework. LOICZ products, such as biogeochemical modelling, link the delivery system to the other two components. Potential users, such as GPA and GIWA, can also be placed into this context. The framework and linkages with DPSIR and some potential international users are shown in Figure 2.

Human Systems - Ecological Systems - Delivery Systems

2.2.4 Functional Clustering

This is the most novel and perhaps the most complex framework to be used by C-GTOS. C-GTOS intends to maintain a broad functional definition that is not strictly defined by geography This approach has led to a framework based on the interaction and overlapping of functional attributes of ecosystems. This is also the framework that best allows the introduction of informatics into the observing system process. Because of the complexity and novelty of the topic, this section describes the functional framework in more detail than others. The level of technicality may not be necessary to all readers. Some may find the following paragraphs sufficient to obtain a sense of this framework.

To address C-GTOS goals, an identification of the commonalities of functions within coastal ecosystems, based on their underlying components (i.e. functional clusters) would be useful on a global or regional scale. The concept of functional clusters implies that admittedly unique systems may nevertheless share some general functions that are aggregates of otherwise different processes and structures. A generic set of such functions can be defined irrespective of their implicit geographic distributions, on the basis of different system components that make them up. The terms of reference of C-GTOS can best be matched by this functional approach, which comprises the following tasks:

A functional view of the coastal zone can be described for C-GTOS purposes in terms of the following kinds of functions:

Functional "clusters" may be defined by specific organism and environmental interactions and assessed through informatics techniques. An inventory of these ecologically necessary resources and processes could be the first step to identifying such functional units. From this inventory one may be able to identify clusters of functions (not in the geographical sense) that relate to important issues in coastal ecology and that define a useful classification of eco-units for research and management purposes. These clusters can be cross-linked to show interactions between processes, sustainability and goods and services and to relate them to traditional ecosystem definitions.

An inventory of ecosystem types has yet to be produced from such a functional point of view. The inventory would produce multiple data layers, or maps, that could be overlaid upon one another. But these maps would not necessarily be of physical features; rather they would represent the ecological functions of ecosystems and the consequent goods and services. Such an approach may lead not to a unique classification of an ecosystem or landscape, but to multiple possible classifications (typologies) that can be tailored to more specific uses. The classification depends on criteria, questions, scale, underlying data and other forms of knowledge, captured as basic models of the functional ecology that can subsequently be mapped for specific needs. This approach is made feasible by the use of relatively common spatial mapping technologies, the relatively new branch of science called informatics, and improved availability of fundamental data, from satellite and in situ observations, on which to base such functional models. Informatics promotes the identification of patterns and arrangement of information from large data sets into new formats through computational techniques. This branch of science helps improve understanding and should significantly contribute to the capabilities of observing systems.


Ecosystem function: What an ecosystem does as an outcome of system behaviour. We refer to two kinds of functions: those that maintain ecosystems and those that provide goods and services to humanity.

Ecosystem process: How the ecosystem does something, internally.

Ecosystem component: A subsystem that is also describable as an ecosystem.

Functional typology: Classification of the different types of functions or functional clusters.

Spatial extent: The spatial relationship between different functional types or clusters.

Ecological functions exist in relationship to observable structures (processes and states) that also determine rates of productivity and resilience and resistance to anthropogenic or natural perturbations. Similar functions may be performed by different structures, and some functions can be defined at a hierarchically higher level and may apply generally in all coastal zone ecosystems. The C-GTOS Panel members identified seven major ecological functions that it believes are generally inherent in all coastal ecosystems (Table 4). Conversely, some functions are ecosystem specific. Both sets of functions (and their supporting structures) exist in harmony to maintain the operation of an ecosystem. Many examples of ecosystem-specific functions can be listed, such as the following:

General and major ecological functions common to all ecosystems and their components



Transporting and storing materials

Biogeochemistry (chemical transformations, nutrient cycling, absorption, nitrification, denitrification, etc.)

Transferring and storing energy

Entropy, dissipation, energy storage, primary and secondary production, etc.

Ensuring availability and quality of air and water

Hydrologic cycles, filtering, cleansing, flows/circulation, BOD, eutrophication, etc.

Ensuring habitat availability

Land conversion, climate change, anthropogenic alterations, landscape or waterscape pattern and process, community structure, substrate dynamics

Generating biological resources

Diversity (number, richness, etc.) and distribution of keystone species, endangered and threatened species, invasive species, genetic resources, etc.

Building trophic networks

Predator-prey interactions, decomposition

Enhancing security (through sustainability)

Response to perturbation (resilience, stability, vulnerability, disturbance, etc.); intrinsic value (integrity, ascendancy, genericity, emergy, etc.)

Ecosystem-specific processes are identified at the regional and systems level by the relevant managers or researchers. Although not all possible systems can be described here, some examples are given in Table 5.

Influences on ecosystem functions, structures, processes and characteristics can be classified in two categories:

Fluctuations in broad-scale forcing functions that have occurred over millennia are the subject of various global research programmes, for example, to predict the effects of global warming, sea level rise, changing weather patterns, etc. on the biosphere and its major ecosystems. Those priorities need not be repeated here. Conversely, there has been inadequate information to assess ecosystem conditions (processes, structures and functions) and potentially manageable phenomena (threats and opportunities) in the coastal zone in any detail (World Resources Institute, 2002; Burke et al., 2001). To complement current assessments (MA, 2003) and outline information for future ones, we have made an initial attempt to identify phenomena that may be in the greatest need of observation in example ecosystems in the coastal zone (Table 4; Table 5). Table 4 classifies the general functions and their underlying processes that we believe are general to all coastal ecosystems. Disruptions or perturbations (anthropogenically induced or not) of any one these will have adverse impacts on any type of ecosystem to some degree or the other; hence observations related to these functions are most critical. The universal and system specific functions for each of the coastal ecosystem types identified are listed in Table 5:

Table 4 and table 5 thus identifies clusters of universal and system-specific functions for any type of ecosystem in any environmental regime and provides a functional classification (typology) of the coastal zone. Not all of the functions and processes are of equal importance, nor do they all act with the same intensity in the same or different climate regimes. Fluctuations and differences on small spatial scales are inevitable. Expertise and knowledge at the local scale backed up by existing databases are essential in identifying the importance of system processes and the degree to which the functioning of the system has been or will be impaired by manageable phenomena. It is also only at the local scale that the degree of management required to sustain a system within the limits of change can be assessed.

Functional clusters and ecosystem types



Ecosystem-specific processes and functions

Manageable phenomena (threats and opportunities)

Goods and services

Resistance1 to manageable phenomena

Resilience2 to manageable phenomena

Coastal wetlands, salt marshes and swamps

  • Filtering capacity
  • Water pulsing
  • Export of organic material
  • Habitation/ urbanization
  • Introduction of non-native species
  • Water extraction
  • Water waste treatment
  • Habitat (system-specific biota)
  • Erosion control
  • Tourism




  • Absorptive capacity
  • Tidal pulsing
  • Habitat/nursery ground
  • Export of organic and inorganic material
  • Exploitation (fish, bait org)
  • Eutrophication
  • Chemical pollution
  • Water extraction catchments
  • Urbanization
  • Input of human pathogens
  • Subsistence food production
  • Transportation
  • Recreation
  • Habitats
  • Property/ habitation
  • Tourism


Low to moderate

Mangrove forests

  • Tidal pulsing
  • Export of organic material
  • Substrate biogenesis
  • Exploitation
  • Water extraction
  • Aquaculture
  • Urbanization
  • Existence value (unique plants and animals)
  • Erosion control
  • Soil formation
  • Habitats



Sea grass meadows and kelp beds

  • Water movement/ currents
  • Habitat/refuge
  • Organic detritus production

· Harvesting
· Eutrophication
· Sediment deposition
· Erosion

  • Biological control
  • Erosion control
  • Habitats/refuge



Sandy beaches and coastal dune/desert systems

  • Filtering capacity
  • Wave regime
  • Export of organic material
  • Fog belts
  • Mining
  • Introduction of non-native plant species
  • Habitation/ harbours/seawalls
  • Breakwaters
  • Artificial dune stabilization
  • Habitat (system-specific biota)
  • Erosion control
  • Storm attenuation
  • Tourism
  • Raw materials (precious metals, diamonds)



Coastal forests and grasslands

  • Water cycle
  • Soil formation
  • Refuge (terrestrial biota)
  • Exploitation (deforestation)
  • Urbanization
  • Introduction of non-native species (plants and animals)
  • Construction (highways, dams)
  • Water regulation and supply
  • Habitat
  • Waste treatment
  • Oxygen and carbon cycles
  • Storm attenuation
  • Tourism
  • Raw material (wood, seeds, grazers)


Low to moderate

1. Resistance is defined as the response of an ecosystem to human-induced perturbations (i.e. manageable phenomena). "Low" resistance implies that the system is susceptible to these perturbations/activities and will be negatively affected.

2. Resilience is defined as the ability of the system to respond positively to the curtailment or amelioration of manageable phenomena. "Low" means that the system's ability to "recover" is permanently impaired and that it will probably continue to exist in a different ecological state than before.

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