|Some problems of vertical distribution of meso- and macroplankton in the ocean|
Vinogradov, M.E. (1997). Some problems of vertical distribution of meso- and macroplankton in the ocean. Adv. Mar. Biol. 32: 1-92
In: Advances in Marine Biology. Academic Press: London,New York,. ISSN 0065-2881, more
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The plankton in the whole water column depends on photosynthetic production in the upper layer, the euphotic or epipelagial zone, where there are zooplankton that remain in this layer all the time. Below is the deep-sea zone, with animals that show different vertical distributions in the different climatic regions of the Ocean. As defined here, mesozooplankton has a size range of 200 µm to 30 mm length, but including also chaetognaths and polychaetes up to 50 mm. Macroplankton ranges up to 150 mm, and includes large shrimps and the gelatinous animals such as medusae, siphonophores and ctenophores; fish and squid in this size range are conventionally classed as micronekton. Methods of sampling depend on the size range. Most mesoplankton is taken with vertical closing nets and large water bottles, while macroplankton requires horizontal or oblique tows of large nets and trawls, but both types of gear require closing devices or depth telemeters to control the sampling depth. Manned submersibles have extended the range of quantitative observations on plankton, and show that both meso- and macroplankton samplers underestimate the true abundance of many species. Patterns of mesoplankton distribution are listed for the different depth layers and the importance of small scale spatial variability is emphasized. Comparisons are then made of the distribution and abundance of mesoplankton over the whole water column in the open oceans. Macroplankton is more difficult to assess quantitatively than mesoplankton. Its composition and depth distribution are summarized and the importance of gelatinous animals emphasized. A scheme is presented for classifying the vertical distribution of plankton based mainly on biological criteria. Regional and climatic variations affect the boundaries of the different zones.The final section reviews the special conditions near the sea bottom where there are distinct communities of benthopelagic animals. Nutritional conditions are very variable near the bottom and there can be a high proportion of dead animals. Chemosynthetic input from mid-ocean ridge vent communities is relatively unimportant to the pelagic community.