Excavating Behavior Increases Ecosystem Biodiversity

a stocky red fish swims underwater in dark blue water

Biological Strategy

Red grouper

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Control Erosion and Sediment

Ecosystems must maintain their soils on site and prevent it from being washed away. Organic matter, minerals, and other nutrients in soil support organisms from microorganisms to the largest mammals. But because of the pull of gravity, water flows unless impeded. Therefore, the presence and actions of many, diverse organisms hold soils in place and slow water to allow sediments to settle out rather than be washed downhill. For example, in forests, downed logs that fall crossways to the slope efficiently slow water flow, trapping soils carried by the water and causing water to soak into the soil. In areas lacking logs and other structures, water can flow so fast that it cuts into the soil, causing erosion that washes the soil away.

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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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Excavating behavior of red groupers increases biodiversity in reef communities because they create and maintain habitats.

“Red grouper (Epinephelus morio) is an economically important species in the reef fish community of the southeastern United States, and especially the Gulf of Mexico…Working both inshore in Florida Bay, Florida (U.S.A.), and offshore in the Gulf of Mexico shelf-edge fishery reserves…we characterized red-grouper habitat and the associated faunal assemblages and demonstrated through a series of experiments that red grouper expose rocky habitat by excavating with their mouths and fanning with their fins to clear away surficial sediment, thereby providing habitat for themselves as well as other reef-dwelling organisms. They also maintain this habitat by periodically clearing away sediment and debris. Such maintenance provides a clean rocky substrate for the attachment of sessile invertebrates, thereby modifying habitat features to provide refuge for many other species of fish and motile invertebrates. We demonstrated increased and abundance associated with habitat structured by red grouper, and we speculate here as to its fishery importance as habitat for other economically important species such as spiny lobster (Panulirus argus) and vermilion snapper (Rhomboplites aurorubens).” (Coleman et al. 2010:1)

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http://marinefeeder.magnet.fsu.edu/faculty/papers/1TOFISHSJ.pdf
http://marinefeeder.magnet.fsu.edu/faculty/benthichabitat.aspx

Last Updated August 18, 2016

References

Journal article

Benthic Habitat Modification through Excavation by Red Grouper, Epinephelus morio, in the Northeastern Gulf of Mexico

TOFISHSJ | 13/01/2010 | Felicia C. Coleman, Christopher C. Koenig, Kathryn M. Scanlon, Scott Heppell, Selina Heppell, Margaret W. Miller

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