Effects of biological disturbance by benthic amphipods Monoporeia affinis on meiobenthic community structure: a laboratory approach

Abstract

In order to evaluate the importance of biological disturbance on meiofaunal communities in muddy habitats, a laboratory experiment was performed at the Asko Laboratory in the northwestern Baltic proper The benthic amphipod Monoporeia aff~nis (Lindstrom) was added to microcosms containing sublittoral mud, in quantities varying from zero up to 80 ind. 104cm-~ After 2 mo the density of nematodes, the most abundant meiofauna taxon (97 %), was greatest in microcosms without amphipods, but they also occurred in higher numbers in microcosms containing a high density of M.affinis, compared to low and medium density microcosms. M. affinis appears to have a negative effect on surface-dwelling nematode species but a positive effect on the deeper dwelling Daptonema sp.However, nematode assemblage structure remained very similar in all treatments. Copepod abundances increased with increas~ng numbers of amphipods (p <0.002) and were highest in the high density microcosms. In the microcosms without amphipods, Macoma balthica spat was almost twice as abundant as in the amphipod treatments. For kinorhynchs and turbellarians there were also significant differences between treatments. The different responses of the major taxa to the biological disturbance may reflect the multifactorial nature of biotic perturbations.

Intraspecific competition for food within and between year classes in the deposit-feeding amphipod Monoporeia affinis-the cause of population fluctuations?

“…It utilises benthic bacteria (Ankar 1977, Goedkoop & Johnson 1994) and settled phytoplankton as food (Lopez & Elmgren 1989, Aljetlawi et al 2000, van de Bund et al 2001, while meiofauna seem not to be important (Ólafsson & Elmgren 1991). The main period of growth is during the spring diatom bloom and a few months thereafter (Cederwall 1977, Elmgren 1978, Sarvala 1986, Sarvala & Uitto 1991, Lehtonen & Andersin 1998.…”

Uptake of phytodetritus by three ostracod species from the Baltic Sea: effects of amphipod disturbance and ostracod density

“…Ólafsson et al (1999) hypothesized that this could be explained by vertical segregation in the sediment or resource partitioning. The 3 ostracod species are confined to the top cm (Ólafsson & Elmgren 1991(Ólafsson & Elmgren , 1997(Ólafsson & Elmgren , Ólafsson et al 1999), but they may have different vertical distribution within this sediment layer. Meiofauna can be vertically segregated on a mm scale in the sediment (Joint et al 1982, Warwick & Gee 1984, Fleeger et al 1995.…”

“…Sediment disturbance can change meiobenthic species abundance sufficiently to alter community structure (Thistle 1980, Creed & Coull 1984, Coull & Palmer 1984 and references therein, Kneib 1985, Palmer 1988, Warwick et al 1990, Ólafsson & Elmgren 1991, Aarnio et al 1998, Schratzberger & Warwick 1998. Meiofauna species and taxa often respond differently to disturbance, which may partly be explained by differences in their vertical distribution.…”

“…Meiofauna species and taxa often respond differently to disturbance, which may partly be explained by differences in their vertical distribution. It has been demonstrated that the abundance of epibenthic species can be reduced through direct predation, competition or other physical factors, while species dwelling in deeper sediment layers can be promoted after a disturbance event possibly due to enhanced food resources or improved chemical conditions in these layers (Ólafsson & Elmgren 1991). However, epibenthic species can also increase in abundance after both physical (Alongi 1985) and biotic (Ólafsson & Elmgren 1991) sediment disturbance events.…”

A benthic sled for sampling soft bottoms

“…Menzies 1972;Menzies et al, 1973), {3) easy adjustment of cutting bar height, and (4) quick exchange of collecting bags. The sled has functioned well during collections of benthic animals in coastal areas of the Baltic Sea for more than a decade (Lopez & Ehngren, 1989;Abrams et al, 1990;Hill et al, , 1992Olafsson & Elmgren, 1991;Olafsson, 1992;Olafsson et al, 1993;Eriksson et al, 1996). A larger model (cutting breadth 800 ram) has been used successfully for shipboard sampling of epibenthic mysids (Rudstam et al, 1989), and for sampling demersal fish in shallow water by manual hauling ashore (Nellbring, 1988).…”