Trophic interactions between zooplankton andPhaeocystis cf.globosa

Abstract

Mesozooplankton grazing on Phaeocystis cf. globosa was investigated by laboratory and field studies. Tests on 18 different species by means of laboratory incubation experiments, carried out at the Biologische Anstalt Helgotand, revealed that Phaeocystis was ingested by 5 meroplanktonic and 6 holoplanktonic species; filtering and ingestion rates of the latter were determined. Among copepods, the highest feeding rates were found for Calanus helgolandicus and Temora longicornis. ton grazing by the dominant copepod -femora longicorms to be negligible during the Phaeocysti, spring bloom. T longicornis gut fluorescence was inversely related to Phaeocystis dominance. Th~ hypothesis has been put forward that 7". 1ongicornis preferentially feeds on microzooplankton and b) this may enhance rather than depress Phaeocystis blooms. Results from laboratory incubatioc experiments, including three trophic levels -Phaeocystis cf globosa (algael. Strombidinopsis sp Iciliatel and Temora longicornis (copepod) -support this hypothesis.

Models of Plankton Community Changes during a Warm Water Anomaly in Arctic Waters Show Altered Trophic Pathways with Minimal Changes in Carbon Export

“…in the conversion from dimethylsulfoniopropionate (DMSP) to dimethylsulfide (DMS), is considered an antibiotic (Sieburth, 1960) and other growth and grazing inhibitors could be released by this species as well (Nejstgaard et al, 2007, but see Turner, 2015). The production of toxins by phytoplankton has lethal or sub-lethal effects on the microzooplankton, both for ciliates or tintinnids (Verity and Stoecker, 1982;Carlsson et al, 1990;Hansen, 1995). Rosetta and McManus (2003) concluded that ciliates may exert grazing pressure on HAB species early on, potentially contributing to the suppression and decline of Prymnesium minimum and P. parvum before they bloomed, but that ciliate grazing would be relatively ineffective once blooms (and toxicity) developed fully.…”

A Delay-Diffusion Model of Marine Plankton Ecosystem Exhibiting Cyclic Nature of Blooms

“…From the analysis of the previous section, we see that as θ crosses a certain value, namely, θ 0 , two roots of the eigenvalue equation (16) will cross the imaginary axis as a pair of complex conjugates. The solutions to the linearised system will be proportional to e iq·x · e iωt , which implies that the bifurcating solution is periodic both in space and time.…”

“…Substituting (34) in (16), separating real and imaginary parts and differentiating partially we find…”

“…Buskey and Stockwell [14] have shown in their field study that macro-and meso-zooplankton populations are reduced during the blooms of Chrysophyte Aureococcus anophagefferens. A number of field studies [8,15,16] as well as laboratory experiments [17][18][19] have established that toxicity has a great impact on phytoplankton-zooplankton interaction dynamics.…”

The implications of the precautionary principle for biological monitoring

“…Because species of zooplankton such as copepods, have feeding preferences for different species of phytoplankton (Davies et al, 1992), and because they in turn are important links in the marine food web, the change in Phaeocystis abundance could weU have important implications for coastal North Sea ecosystems in general and for fisheries in particular. Yet even a partial untangling of the effects on the food web is a slow process requiring dedicated, painstaking work (Hansen, 1994).…”