| Summary: | Meiofauna are an abundant, diverse and important component of the marine
biota, however, much of their ecology has been neglected. Despite their high densities,
meiofaunal abundance is often patchy. Meiofauna present in high numbers at one site
will often be less abundant in seemingly similar adjacent sites. What factors govern this
variability? How readily do these animals colonize new patches? How do various
biological and environmental factors affect meiofaunal colonization rate and resulting
assemblage structure?
The response of meiofauna to changes in abiotic factors, including sediment grain
size, depth, exposure and distance from the ocean floor, was quite variable. Often one
factor would affect certain taxa and not others. Even slight increases in depth resulted in
drastic declines of harpacticoid copepods while nematodes were unaffected. Meiofauna
were also fewer in sediments with large interstitial spaces. Some meiofauna were most
abundant in sediments placed closer to the ocean floor. Other taxa colonized distant
substrata as rapidly as they did substrate located closer to the ocean floor. This suggested
differences between taxa in their rates of active dispersal.
The effects of macrofauna on meiofauna have been debated. In particular, how do
clams affect the colonization and assemblage structure of meiofauna? Certain
characteristics of clams were isolated and evaluated: feeding behaviour, bioturbation
rate/depth and metabolic byproducts. Clams that caused the greatest meiofauna declines
were shallow burrowing deposit-feeders. Constant disturbance to the upper sediment by
these clams was likely responsible for meiofaunal impact. Conversely, suspensionfeeding
clams that passed quickly to deeper sediment and remained stationary had little
impact on meiofauna.
Finally, a survey of local marine nematodes added nine genera new to Canada
and 24 genera new to British Columbia. A review was also compiled that shows
nematodes and other meiofauna have been neglected for much of Canada. Although
these small and abundant animals are quick to colonize even distant habitats they are
quite sensitive to cues from the surrounding biotic and abiotic environment. This
sensitivity combined with their ease of collection make meiofauna a valuable asset to any
number of ecological investigations. === Ecology
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