Stream Community Depends on Ecosystem Engineers

Biological Strategy

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Cycle Nutrients

In ecosystems, there is no such thing as waste. Instead, one organism’s waste can be considered as another organism’s resource, and the cycling of nutrients may be the most important form of recycling in living systems. But sometimes those nutrients are transformed by one organism into a form that isn’t readily used by other organisms. For example, lignin is a complex organic molecule found in the cell walls of plants. In a forest, it’s one of the hardest molecules to break down in woody vegetation. Therefore, ecosystems include organisms that are particularly well-adapted to break down different types of nutrients. In the case of lignin, some fungi and bacteria release lignin-modifying enzymes that can break down the lignin to form carbohydrates and other life-supporting chemicals.

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Maintain Biodiversity

The greater the amount of genetic and species variation in an ecosystem, the more resilient that ecosystem is to disturbances. Variation in ecosystems across the Earth also contributes to the Earth’s resilience to unpredictable changes. This variation is called biodiversity. Because living systems compete with each other for scarce resources, maintaining biodiversity involves creating conditions for a large variety of species to successfully co-occur and reproduce. For example, within a wetland, there are different vegetation types. This diversity results in a complex mosaic of microenvironments as the vegetation types alter air flows, light regimes, and water temperatures and chemistry. Because organisms vary in their ideal environmental conditions, these micro-environments increase the diversity of plants in the wetland. In turn, having a wetland in an otherwise dry area increases biodiversity at an even larger scale.

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Fish

Class Agnatha (“without jaws”), Class Chondrichthyes (“cartilage fish”), Superclass Osteichthyes (“bone fish”): Sharks, eels, snapper, hagfish

The fish are a diverse group, comprising multiple classes within Phylum Animalia. The most well-known classes are Chondrichthyes, which has sharks and rays, and superclass Osteichthyes, which has all bony fish like cod and tuna. Unlike other vertebrates, fish only live in water. They use special adaptations like fins, gills, and swim bladders to survive. Most are ectothermic, meaning their body temperature depends on the water temperature around them. Over half of all vertebrates are fish. They’re found from the bottom of the sea to high mountain lakes.

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Andean stream communities depend on detritivorous fish that modify habitat structure and resource availability.

“Many organisms modulate the availability of resources to other species by causing state changes in or materials (ecosystem engineering), in the process frequently changing the selection to which the ecosystem engineers and other organisms are exposed (niche construction)…the selective removal of a detritivorous fish (Prochilodus mariae) from a stream in the Andean foothills resulted in the rapid accretion of sediments and significant changes in the composition of algal and invertebrate assemblages (Flecker 1996). Through their modification of habitat structure and resource availability, sediment-processing fish were shown to be key to structuring biotic communities. Overexploitation of Prochilodus fisheries in South America may have broad consequences that are manifested throughout Andean stream ecosystems (Flecker 1996).” (Boogert 2006:570, 573)

Last Updated August 18, 2016

References

Journal article

The Implications of Niche Construction and Ecosystem Engineering for Conservation Biology

BioScience | 19/07/2006 | NEELTJE J. BOOGERT, DAVID M. PATERSON, KEVIN N. LALAND

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