L3 The Benthos Flashcards
Biotopes of the benthos
Intertidal, infralittoral, circalittoral and deep sea
What are the four benthic faunal categories and give examples
Microfauna <0.63um (rotifers and ciliates )
Meiofauna <0.5-1mm (oligochaetes and nematodes)
Macrofauna >0.5-1mm (polychaetes and amphipods)
Megafauna (echinoderms and decapods)
What is bioturbation and what are the processes involved
Bioturbation is the disturbance of sediment by organisms
Physical processes: micro relief (alteration of physical properties eg. Grain size and porosity)
Chemical processes: cycling of C, N and P and increased oxygenation by burrowing waters and removal of buried contaminants
Describe the infralittoral zones ecology and community structure aswell as the environmental requirements
Kelp forests (upper zone) kelp parklands (lower zone)
Common species: laminaria digitata, Laminaria hyperborea aswell as associated epiphytic algae along stipes
Community: sea lions, lobsters, crabs, fish and juveniles
Environmental requirements:
Substrate: hard substratum (euphotic zone)
Light and depth: limited availability depending on location and turbid waters
Tidal currents: limit productivity
Temperature: intolerant to large fluctuations
Chemistry: small salinity range, however kelp forests are efficient absorbers of nitrogen and phosphorus
What is a CFT?
Describe the community of the Circalittoral zone
The environmental requirements of the Circalittoral zone
CFT: circalittoral faunal turf
A CFT has an assemblage of animals growing on hard substrate with varying growth forms from small encrusting sponges to tall stent gorgonians (sea fans)
Community: sessile and mobile organisms such as foliose red algae - no dominating species ; high biodiversity
Environmental requirements:
Temperature- limits distribution
Light- upper limit light expands from 10-20m
Slope of substratum- CFT occur at shallow overhangs or caves
Water movement- influence distribution, exposed environment (large sponges) and sheltered (delicate sea fans)
