Effects of macroepifauna on developing nematode and harpacticoid assemblages in a subtidal muddy habitat

Abstract

In order to assess the effects of macrofauna on meiofaunal community structure, field investigations were performed in a low energy subtidal muddy sediment in Loch Creran, a sea-loch on the west coast of Scotland. Meiofaunal colonization of azoic sediment was studied in cages designed to exclude macrofauna to varying degrees. In all the cages high diversity assemblages developed rapidly. Considerable variation in species composition was found, both for nematodes and harpacticoids, and no indication that exclusion of the macrofauna was influencing the early colonizing individuals. For the harpacticoid species the results from multivariate analyses indicated a strong successional pattern inside the cages. However such a pattern was not obvious for the nematode component of the meiofauna. The semi-pelagic harpacticoid copepod Longipedia helgolandica became extremely abundant inside the cages, while it was hardly found in the background sediment. The initial colonization by most of the harpacticoids was marked by a high proportion of copepodites. The exclusion of macroepifauna did not result in a simpler meiofaunal community as one would expect i f suppression of dominant competitive relationships by macroepifauna occurred. This study emphasizes the complexity of the community organization, where multitrophic relationships may be of vital importance as factors influencing community structure.

Influence of epibenthos on meiobenthos of the Ceriops tagal mangrove sediment at Gazi Bay, Kenya

“…Bioturbation. It has been postulated that sediment reworking activities are an alternative structuring force (Bell & Coull 1978, Reise 1979, Webb & Parsons 1991, Olafsson & Moore 1992. Our experiment did not show this kind of effect.…”

“…Predation on meiofauna is either selective or non-selective (Bell Bay & Coull 1978, Reise 1979, Tenore & Rice 1980, Gee et P B P al. 1985, Marinelli & Coull 1987, Gee 1989, Hall et al C C B 1990, McLachlan & Romer 1990, Caste1 1992, Olafsson & Moore 1992, Giere 1993.…”

“…If this is the case, the meiobenthos depends on, or competes with, the other benthic subsystems (such as the epibenthos) for detrital food (Reise 1979, Heip 1980, Connell 1983, Gee et al 1985, Olafsson & Moore 1992, Alkemade et al 1993, Giere 1993, Walters & Moriarty 1993. ( 2 ) On the other hand, several trophic links with the epibenthos have sign.…”

Free-living marine nematodes actively choose habitat when descending from the water column

“…It also seems that the process in intertidal areas is mostly dominated by passive movement of nematodes, as species compositions in the water column and the bottom have been noted to be very similar (Bell & Sherman 1980, Commito & Tita 2002. In subtidal areas, active movement of nematodes may be much more important, as species composition in colonized areas has been found to be different from that in background areas (Alongi et al 1983, Ólafsson & Moore 1992.…”

Spatial heterogeneity of benthic copepods: a comparative aspect on composition, abundance, and correlation

“…They inhabit a wide diversity of habitats from the littoral zone to great depths, as associates or parasites of several multicellular animals and plants, and also in sea ice (Coull et al 1982;Grainger 1991). The patchiness of meiobenthos has been influenced by availability of food and oxygen and other environmental factors (Hicks and Coull 1983;Mantha et al 2012a) and even by macrofaunal bioturbation (Ólafsson and Moore 1992;Ólafsson 2003). Although sediment granulometry is a major structuring factor of meiofaunal population (Ólafsson 1995;Boucher 1997;Ndaro and Ólafsson 1999;Semprucci et al 2010), benthic primary producers such as micro-and macroalgae and higher plants have great influence on the assemblages of benthic fauna which continue to live an epifaunal transition mode of life (Jayabarathi et al 2012;Anandavelu et al 2013).…”