Marine organisms are integral to almost all biogeochemical processes that sustain the biosphere, and provide a variety of products and natural services which are the foundation of the global economy and essential to our well-being. They are responsible for the production of food (about 100 million tons annually) and natural substances, ingredients for biotechnology and pharmaceuticals, and even the creation of land.
Marine ecosystems deliver natural services that are crucial to the balanced functioning of the Earth. These include the production and mineralization of organic material, the storage of pollutants and waste products from land, and coastal protection from natural disasters (mangroves, dune-beach systems, coral reefs).
Resistance to Invasions
Scientists are investigating how biodiversity, or a variety of different species, affects the ability of a native ecosystem to resist invasions by non-native species. They have observed that species-poor island communities are more vulnerable to invasions and that decreasing native diversity increases the ability of invaders to survive. Communities with increased diversity, on the other hand, more completely and efficiently use available space, decreasing the chance for successful invasions.
Marine Food Webs
The structure of marine ecosystems is largely defined by the relationships between predator and prey, or who eats whom. A diagram of these relationships tends to resemble a spider web, thus the term “food webs.” Interruptions in food webs are found when overfishing changes the balance of species or other stress on the ecosystem causes species reduction or extinction. This, in turn, leads to unstable ecosystems.
We are particularly concerned about overfishing on species that form the base of critical food chains -- forage fish, such as a variety of herring species, upon which cod, tuna, and other valuable fish depend. Herring have long been fished at low levels with small-scale gear to satisfy bait needs for lobster and recreational fisheries; however, they are now being fished on a far greater scale for industrial uses. When large schools of fish are scooped up, they are temporarily eliminated from fished areas, affecting other species that need them for food. To restore healthy populations of the numerous commercial fisheries species that have declined, there must be a constant adequate supply of forage fish to support their increased growth.
OCF advocates management policies that will rebuild and maintain food webs and recover healthy ecosystems that support healthy populations of commercially valuable fish.