Meiofauna of an experimental soft bottom ecosystem - effects of macrofauna and cadmium exposure

Abstract

The effects of macrofauna (the amphipod Pontoporeia affinis) and of exposure to cadmium at 0 (control) and ca 5, 50 and 150 pg 1-' on a meiofauna population were studied in s m d , flow-through laboratory microcosms. Meiofauna was derived from a soft sediment benthos community, typical below the therrnochne in the northern Baltic proper (salinity 6 to 8 %). In a first expenment (265 d) subadult amphipods were added, while in a second experiment (460 d) both juveniles and subadults were included. After 265 d at natural field amphipod densities total meiofauna abundance was lower than in control experiments without amphipods. This was due mostly to lower nematode abundance, but also to fewer ostracods. In contrast, non-nematode meiofauna, in particular Turbellaria and harpacticoids, increased in the presence of amphipods. Effects of cadmium exposure on the meiofauna could thus be due either to drect toxicity, or to changes in macrofauna1 abundance or activlty caused by cadmium. Sedlment cadmium concentration was a highly significant function of cadmium concentration in the Input water. Dose-response relationships with sediment cadmium concentration as the Independent variable were significantly negative in the presence of amphipods at 105 d for the abundance of nonnematode meiofauna and Turbellaria and for the biomass of non-nematode meiofauna and of total meiofauna, and at 265 d for ostracod abundance, harpacticoid abundance, total meiofauna biomass and biomass of non-nematode meiofauna. At 265 d in the absence of amphipods, a significant negative dose-response relationship was found for nematode abundance and a positive relationship for turbellanan abundance. Significant negative dose-response relationships were also obtained in the second experiment (460 d , with amphlpods) for total meiofauna abundance and biomass, non-nematode biomass, nematode abundance, ostracod abundance and turbellarian abundance. Overall, ostracods were found particularly sensitive to cadmium exposure, while Turbellana and monothalamous Forarmnifera sometimes increased in cadmium-dosed microcosms, presumably due to reduced competition or predation. The microcosm system tested was found suitable for long-term experiments, and could maintain a near-natural density of meiofauna and P, affinis for over 1 yr. Such long-term experiments demonstrated effects of cadmium even at a concentrahon as low as 6 pg 1 -l , in the presence of sediment.

Meio- and macrofauna in the marine area of the Monte St. Bartolo Natural Park (Central Adriatic Sea, Italy)

“…This observation, together with the enhancement of polychaetes, particularly inshore, supports the hypothesis of human disturbance effects in the coastal area of the Monte San Bartolo Natural Park. The abundance increase of the most sensitive taxa offshore (harpacticoid copepods, amphipods, ostracods) (Van Damme et al 1984, Sundelin and Elmgren 1991, Fabroccini et al 2005) is in accordance with this supposition. However, the statistical analysis has revealed small differences between the two depths in terms of the total community structure, thus underlining that the disturbance affecting the local coastal system can be regarded as moderate overall.…”

Habitat modification mediated by motile surface stirrers versus semi-motile burrowers: potential for a positive feedback mechanism in a eutrophied ecosystem

“…Sundelin & Elmgren 1991) and may inhibit settling or decrease the survival of recruits of other sediment-dwelling species (Rhoads & Young 1970). In the present study, Monoporeia and Mysis increased turbidity and the amount of suspended solids in the water column, indicating that activities by these species loosen the structure of the sediment surface.…”

Malformations in embryos of the deposit-feeding amphipod Monoporeia affinis in the Baltic Sea

“…Two recipient areas that embryogenesis is even more sensitive than other outside pulp mills on the Swedish coast of the Bothnian variables of the reproduction cycle. The microcosm Sea (industry A) and the Bothnian Bay (industry B) develops in good accordance with the parent system were surveyed in 1991 and 1996 respectively and a in situ, suggesting the results are relevant to natural recipient area outside an alurninum smeltery (industry conditions (Sundelin 1989, Sundelin & Elmgren 1991. C) on the coast of the Bothnian Sea was investigated in However, before the embryo variables can be used for 1994.…”