Linkages to Other Coastal and Marine Environments and Processes
In the marine environment, all habitats are ultimately connected – and water is the great connector. Some habitats are more intimately and crucially connected, however. Coral reefs provide a good example of this interconnectedness. For years people thought of the diverse and biologically rich coral reefs as self-contained entities: very productive ecosystems with nutrients essentially locked up in the complex biological community of the reef itself. However, we have come to realize that many of the most crucial nursery habitats for reef organisms are actually not on the coral reef itself, but rather in seagrass beds, mangrove forests, and sea mounts sometimes far removed from the reef71 72. Thus when we think of the coral reef ecosystem – or when we move to conserve it – we must take into consideration these essential linked habitats as well73. Currents and the mobile organisms themselves provide the linkages among the reefs, nursery habitats, and places where organisms move to feed or breed, including the open ocean74 75 76.
The ocean and coastal habitats are not only connected to each other, they are also inextricably linked to land77. Freshwater is the great mediator here: rivers and streams bring nutrients as well as pollutants to the ocean, and the ocean gives some of these materials back to land via the atmosphere, tides and seiches, and other pathways as well, such as the deposition of anadromous fish (fish that live most of their life in the ocean but breed in fresh water) after spawning78 79. Many nursery habitats, such as estuaries, are tied closely to land and are greatly affected by land use and terrestrial habitat alteration80 81, which may disrupt seasonal pulses of freshwater, and often lead to either sediment depletion or overloading.
71 Hatcher et al. 1989.
72 Jameson et al. 2001.
73 Hatcher et al. 1989.
74 Dayton, P.K., S.F. Thrush, M.T. Agardy and R.J. Hofman. 1995. Environmental effects of marine fishing. Aquatic Conservation: Marine and Freshwater Ecosystems 5: 205-232.
75 Mann and Lazier 1991.
76 Simenstad et al. 1999.
77 Agardy 1999.
78 Deegan, L.A. 1993. Nutrient and energy transport between estuaries and coastal marine ecosystems by fish migration. Canadian Journal of Fisheries and Aquatic Science 50:74-79.
79 MA 2005.
80 National Research Council. 1995. Understanding Marine Biodiversity: A Research Agenda for the Nation. Washington, DC: National Academy Press.
81 National Research Council. 1999. Sustaining Marine Fisheries. Washington, DC: National Academy Press.