Coastal Systems


FM1 Semi-confined transitional waters, MT1 Shoreline systems, MT2 Supralittoral coastal systems, MFT1 Brackish tidal systems, M Marine shelfs, MT3 Anthropogenic shorelines, M4 Anthropogenic marine systems

Semi-confined transitional waters

biome is comprised these Ecosystem Functional Groups (EFG): Deepwater coastal inlets, Permanently open riverine estuaries and bays, Intermittently closed and open lakes and lagoons. The Transitional waters biome includes coastal inlets that are influenced by inputs of both fresh and marine water from terrestrial catchments and ocean tides, waves and currents. They include deep-water coastal inlets or fjords mostly restricted to high latitudes, as well as estuaries, bays and lagoons, which are scattered around coastlines throughout the world. Gradients in water regimes, water chemistry, depth, temperature, size and salinity influence the function, productivity, diversity and trophic structure of these transitional ecosystems. The balance between marine or freshwater influences varies seasonally and inter-annually, depending on the climate and among inlets with differing geomorphology, catchment size, climate and exposure to waves and currents. In some cases, ecosystems characteristic of the marine shelf biome (i.e. M1.1 Seagrass meadows) may have significant occurrences within semi-confined transitional waters. Some inlets are permanently connected to the ocean, but others are only intermittently connected, influencing exchanges of water, nutrients and biota among ecosystems. The dynamics of connection and closure of shallow inlets are regulated by variations in steam flow inputs and wave activity. Strong horizontal and vertical salinity gradients (varying with freshwater and marine inputs) structure biotic communities and traits that equip species for occupying different salinity niches. Autochthonous energy generated by primary production from aquatic macrophytes, phytoplankton, macroalgae and diatoms is subsidised by allochthonous inputs from inlet shorelines, freshwater streams and marine incursion. These high levels of energy availability support complex trophic networks, including large populations of macroinvertebrates, fish, waterbirds, seabirds and some mammals and reptiles. Many inlets function as fish nurseries and bird breeding sites.

Shoreline systems

biome is comprised these Ecosystem Functional Groups (EFG): Rocky shores, Muddy shores, Sandy shores, Boulder and cobble shores. The Shoreline systems biome comprises naturally formed, intertidal abiogenic habitats situated at the interface between land and sea. The distribution of the biome spans all latitudes (temperate to polar) at which landmasses are present. Productivity ranges from high to low, is loosely proportional to the availability of stable hard substrate for macrophyte attachment and inversely proportional to the dependency on allochthonous energy sources derived from both land and sea. Productivity is also influenced by coastal upwelling and, for ecotypes of finer particle size, the nutrient content of adjacent terrestrial sediments. Within and across ecotypes, biotic communities are strongly structured by tides, waves and particle size, ranging from contiguous rock to fine silts and clays. Notably, some shorelines comprise mixed hard and soft substrates, with vertical zonation varying temporally in response to storm events and redeposition of soft sediments. Tides produce a vertical gradient of increasing aerial exposure across which desiccation and temperature stress increase, time available for filter-feeding decreases, and interactions with marine and terrestrial predators vary. Waves and particle size determine substrate stability and the physical disturbance regime. Wave action, diminishing from headlands to bays, produces horizontal gradients in community structure. Many organisms possess morphological and behavioural adaptations to prevent desiccation at low tide and dislodgement by wave forces. Burrowing animals are important in unconsolidated sediments. Competition (especially for space) is a major factor structuring communities, with its importance diminishing with decreasing particle size. Facilitative interactions (particularly those that protect organisms from desiccation stress or physical disturbance) can be important across ecosystems of all particle sizes. Biodiversity is generally high, with microscopic lifeforms dominating the biomass of systems of small particle size.

Supralittoral coastal systems

biome is comprised of the Ecosystem Functional Group (EFG): Coastal shrublands and grasslands. The Supralittoral coastal biome marks the landward extent of the transition from marine to terrestrial biomes. It is elevated above the direct influence of waves and tides (see MT1) and beyond the direct influence of freshwater seepage or rivers (see MFT1). Supratidal coastal ecosystems extend around all the world’s land masses, occupying a fringe from tens of metres to a few kilometres wide and covering the entire extent of many small islands. Onshore winds, created by differences in air pressure related to the differing heat capacities of water and dry land, are a key driver of ecosystem function. These winds create desiccating conditions on elevated landforms, such as headlands and coastal dunes, as well as continual inputs of aerosol salts and salt spray. Even though the supralittoral zone is located above high spring tide, it is exposed to recurring disturbance from storms producing exceptional waves and tides that reduce standing biomass and destabilise substrates. These strong environmental gradients select for a specialised, low-diversity biota. Much of this biota is confined to supralittoral ecosystems and nowhere else, a key feature of these ecosystems, although it may be widely distributed behind shorelines on different land masses due to dispersal by coastal winds, oceanic currents, and/or migratory behaviour. Autochthonous energy is produced by wind-pruned vegetation with traits promoting tolerance to desiccation, high salinity and substrate instability (e.g. stomatal regulation, extensive rhizomes or root systems and succulence). The sea supplies allochthonous energy subsidies, such as wrack and guano, but also transports a portion of primary production to other ecosystems. Invertebrate detritivores and physical weathering contribute to rapid decay. Supralittoral ecosystems also provide nesting habitat for seabirds on the surface, in vegetation or in burrows, especially on islands free from terrestrial mammalian predators.

Brackish tidal systems

biome is comprised these Ecosystem Functional Groups (EFG): Coastal river deltas, Intertidal forests and shrublands (i.e. mangroves), Coastal saltmarshes and reedbeds. The Brackish tidal systems biome is associated with prograding depositional shorelines at the interface of terrestrial, freshwater, and marine realms. The relative influences of marine, freshwater, and terrestrial processes vary from strongly fluvial deltas to marine-dominated intertidal forests and terrestrial-dominated coastal saltmarsh. Autochthonous sources of energy, contributed by flowering plants and algae, are supplemented by allochthonous sources delivered by rivers, currents, and tides. These sources support high productivity and complex trophic webs that include highly mobile fish and birds that rely on brackish tidal systems to complete their lifecycles. Standing plants assimilate energy and engineer habitat structure for epifauna and epiflora as well as juvenile fish nurseries. They also promote sediment deposition by dampening wave and tidal energy. While terrestrial systems are the ultimate source of most sediment, fluvial and marine processes redistribute it and drive patch dynamics across temporal and spatial scales. Brackish tidal systems are structured by steep local gradients in salinity and tidal exposure. Physiological traits that confer differential fitness and competitive abilities, together with differential predation pressure, mediate species turnover along gradients. Brackish tidal systems are distributed on depositional coastlines throughout the world.

Marine Shelfs

biome is comprised of these Ecosystem Functional Groups (EFG): Seagrass meadows, Kelp forests, Photic coral reefs, Shellfish beds and reefs, Photo-limited marine animal forests, Subtidal rocky reefs, Subtidal sand beds, Subtidal mud plains, Upwelling zones. The Marine shelf biome is distributed globally between the shoreline and deep sea-floor biomes and is dominated by benthic productivity. It includes ecosystems with biogenic substrates (such as seagrass meadows, kelp forests, oyster beds and coral reefs) and minerogenic substrates, including rocky reefs, sandy bottoms and muddy bottoms. The availability of light and nutrients are key structuring factors, influencing productivity and ecosystem structure and function. Turbidity and depth gradients influence light availability. Productivity depends on upwelling currents that deliver nutrients from the deep ocean floor, as well as the strength of nutrient inputs from the land, delivered largely by fluvial systems. Light is influenced by depth gradients, but also by water clarity (cf. turbidity), and determines whether macrophytes and animals dependent on photosynthetic symbionts are able to establish and persist. Additionally, whether the bottom type is hard or soft dictates whether sessile organisms can dominate, forming biogenic habitats that protrude into the water column. A shallow water biome, the marine shelf is shaped by kinetic wave energy and, in polar regions, also ice scour. Positive feedback loops, whereby the habitat structures formed by sessile organisms dampens kinetic energy, can enable ecotypes to persist under marginally suitable conditions. The strength of top-down control by consumers can be an important factor in determining community structure. Depending on the benthic biota, energy sources can vary from net autotrophic to net heterotrophic. Temperature and, to a lesser extent, salinity influence the presence and identity of dominant habitat-forming biota. Currents can influence ecotypes by determining patterns of larval dispersal and the flow of resources.

Anthropogenic shorelines

biome is comprised of the Ecosystem Functional Groups (EFG): Artificial shores. The Anthropogenic shorelines biome is distributed globally where urbanised and industrial areas adjoin the coast, and includes some more remote structures such as artificial islands. It includes marine interfaces constructed from hard, smooth surfaces, including concrete, timber, lithic blocks and earthen fill, adjoining, extending or replacing natural shores, or floating in proximity to them. These relatively homogeneous substrates support an opportunistic, cosmopolitan biota with limited diversity and simplified trophic structure compared to other shoreline systems. Vertical surfaces are inhabited by algae and biofouling species but are exposed to strong tidal desiccation regimes that strongly filter potential colonists. Floating structures have downward-facing, usually smooth, surfaces, unlike almost anything in nature, which may be colonised by opportunists. Influx of storm water and effluent enhances nutrient levels and eutrophic algae, which contribute autochthonous energy. Outflows from developed areas are also major sources of allochthonous energy. Strong bottom-up regulation stems from these resource inputs and from low populations of predators, which are depleted or deterred by human activity.

Anthropogenic marine systems

biome is comprised of the Ecosystem Functional Groups (EFG): Submerged artificial structures and Marine aquafarms. Humans have constructed, deposited or dumped artificial structures in the oceans that either confine managed marine organisms or attract marine biota that would not otherwise occupy such locations. These structures are distributed globally but are most common in regions of high-density occupation or transit. They include shipwrecks and mineral, gas, or energy infrastructure, pipelines, and rubble piles, as well as aquaculture infrastructure. These installations provide an epibenthic substrate for sessile benthic organisms, as well as a demersal or pelagic environment for mobile organisms. Diversity and biomass of the epibenthic biofouling community is positively related to substrate rugosity. Most energy is supplied to these ecosystems from allochthonous sources, either passively via currents or actively through addition by humans (as is thecase in aquaculture). Epibenthic and planktonic marine algae, however, make a contribution to the energy budget through local primary production. Microbial decomposers and invertebrate detritivores in the sediments beneath and around the structures feed on particulate organic matter from the epibenthic biota (e.g. waste products and decaying bodies) or on unconsumed food delivered to managed species. The elevated productivity or visual features of artificial structures often attract larger pelagic predators, which forage in the vicinity.


The Coastal systems (including wetlands) biome in ESVD is comprised of Sand dunes, beaches, rocky shores, Tidal marshes, Salt marshes, Mangroves, Lagoons, Estuaries, Unvegetated sediment, Shellfish reefs, Seagrass beds, Kelp forests, Other (coastal systems)


FEMA has three coastal categories: Coastal wetlands, Beaches and Dunes, Shellfish reefs, and Coral Reefs.

Coastal wetlands are defined as: Areas of tidal wetlands (herbaceous and/or woody vegetation) or deepwater habitats in which plants grow and form a continuous cover principally on or at the surface of the water (e.g., algal mats, kelp beds, and submerged aquatic vegetation); AND vegetation coverage is greater than 20%; AND these waters are tidally influenced and have a salinity greater than or equal to 0.5 parts per thousand. This definition of coastal wetland is a combination of several categories within the Coastal Change Analysis Program (C-CAP) Regional Land Cover Classification Scheme for Estuarine Wetlands developed by NOAA, 40 which is a nationally standardized inventory of land cover for the coastal areas of the U.S. Specifically, the following categories have been captured: Estuarine Forested Wetland (16); Estuarine Scrub/Shrub Wetland (17); Estuarine Emergent Wetland (18); and Estuarine Aquatic Bed (23).

Beaches and Dunes are defined as: Areas consisting of material such as silt, sand, or gravel that is subject to inundation and redistribution due to water or wind. Substrates have no vegetative cover except for pioneering plants that are briefly established when growing conditions are favorable. This definition of beaches and dunes is based on the Coastal Change Analysis Program (C-CAP) Regional Land Cover Classification Scheme definition of Unconsolidated Shore. This is a nationally standardized inventory of land cover for the coastal areas of the U.S. developed by NOAA.

Shellfish Reefs are defined as: Areas where the substrate is dominated by living or non-living shell reefs and are surrounded and intermixed with channels and unvegetated flats, typically occurring in the intertidal zone. This definition of shellfish reefs is based on the 2012 Federal Geographic Data Committee (FGDC) Coastal and marine ecological classification standard similar to the “Classification of Wetlands and Deepwater Habitats in the United States”.

Coral Reefs are defined as: Areas of hardened, fixed substrate or structures created by deposition of calcium carbonate by reef- building coral species. May include both deep- and shallow-water coral species. This definition of coral reefs is based on the Coastal and Marine Ecological Classification Standard (CMECS),255 a national framework which organizes information about coasts and oceans. CMECS is endorsed by the Federal Geographic Data Committee (FGDC) as the national standard for classifying coastal and marine areas.

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