Meiobenthos of Sub-Littoral Muds

Abstract

SUMMARYMeiobenthos, here defined as metazoans passing through a ½ mm screen, is described from core samples collected on muddy grounds at 100-140 m depth in the North Sea and off the west coast of Scotland between February 1962 and August 1963.Sixteen cores of 2·2 cm diameter were collected from Loch Nevis, and 14 from the Fladen ground. The top 7 cm of each core was passed through a 500μ then a 76μ screen. The residues were examined entire, and the nitrate of the finest mesh was subsampled.The fauna consisted mainly of nematodes, kinorhynchs, ostracods, copepods, polychaetes, and lamellibranchs. Between 61 and 97 % of the population consisted of nematodes, but copepods were second in importance and were more abundant than recorded on other subtidal grounds.The fine mesh (76μ) retained almost all specimens of every animal group except Nematoda. Numerically 38% of the nematode population passed through the fine sieve, but this represented only 18% by weight.The mean dry weight of meiobenthos on Fladen was calculated as 0·76 g/m2 and the average number of individuals was 196 × 104/m2.In Loch Nevis the corresponding weight was 1·28 g and the number 101 × 104. The loch had a larger and more varied population of all groups except nematodes, which were particularly abundant on Fladen.The data do not indicate significant population fluctuations throughout the year in the permanent meiobenthos.Compared with other subtidal grounds Nevis and Fladen seem to support much richer populations, and the high values for Fladen are of particular interest since this is a poor macrobenthos area.An attempt is made to indicate the possible level of meiobenthos productivity and it is suggested that there may be competition between meio- and macrobenthos for available organic matter which could result in a less efficient production of fish food.

Composition, Distribution, Abundance and Biomass of the Macrofauna and Meiofauna of Four Sandy Beaches

“…Similar extrapolations for 1 m wide transects have been done by Ansell eta/ (1972), Hanekom (1975, McLusky eta/ ( 1975) and McLachlan ( 1977b ). These total beach biomasses were then converted to production estimates by multiplying by a turnover of 10 for the meiofauna (Mcintyre 1964;Gerlach 1971) and 2,5 for the macrofauna.…”

“…The tertDII macrofauna and meiofauna have in the literature been considered merely arbitrar)t'sizc..divisions of the metazoan benthos based on practical differences in collection (Mcintyre 1964(Mcintyre , 1969Muus 1967;Swedmark in Hulings & Gray 1971). Mcintyre (1968) noted, however, that on tropical sandy beaches the meiofauna diffen from the macrofauna not only in size but also in the ecological niche it fills.…”

“…Comparisons on the basis of numbers favour the meiofauna while biomass comparisons favour the macrofauna and ecologically significant comparisons should be based on production or energy flow values. Such comparisons would necessitate very long term study and for practical purposes the best comparison is on the basis of production values estimated from biomass values and a knowledge of turnover rates (Mcintyre 1964;Arlt 1973;McLachlan 1977b ). McLachlan (1977b) did this for two beaches and found that the meiofauna made up significant percentages of the total metazoan production in both cases.…”

An Ecophysiological Study of the Meiofauna of the Swartkops Estuary

“…Subtidal distribution is dealt with by Mcintyre (1964), Coull (1970) and Warwick & Buchanan ( 1970). The intertidal distribution and composition of the meiofauna in exposed beaches is well documented by Janssen ( 1967,1968) in the Baltic, Gray & Rieger ( 1971) in Yorkshire, Wieser eta/.…”

Studies from the “UWL Helgoland” on the macrobenthic fauna of rocks and boulders in Lübeck Bay (western Baltic Sea)

“…This sampler is designed to collect the macrofauna, i.e. all animals which are retained by a 0.5 mm sieve (Mclntyre, 1964;Holme & Mclntyre, 1971).…”