High reproduction, but low biomass: mortality estimates of the copepod Acartia tonsa in a hyper-eutrophic estuary.
2008 (English)In: AQUATIC BIOLOGY, ISSN 1864-7790, Vol. 2, no 1, 93-103 p.Article in journal (Refereed) Published
Production, abundance and mortality of the copepod Acartia tonsa were studied for a period of 9 d in a hyper-eutrophic estuary, Mariager Fjord, Denmark. The estuary is characterised by oxygen-depleted and often sulphidic bottom water, and a relatively sparse mesozooplankton community with low species diversity. During the study, an intense phytoplankton bloom consisting mainly of the diatom Skeletonema costatum developed with chlorophyll a concentrations reaching 46 mu g l(-1). Egg production rate (EPR) in A. tonsa ranged from 30 to 65 eggs female(-1) d(-1), and egg hatching success was > 90 %, yet the abundance of copepods remained low (1 to 3 nauplii l(-1), 0.3 to 1.5 copepodites l(-1)). Calculated daily copepod mortality ranged from 18 % for nauplii, 16 % for Copepodite Stage C 1, up to 70 % for C2 and C3, then declining for older stages. The vertical distribution of copepodites in relation to the depth range of mussel beds suggests strong predation by suspension-feeding Mytilus edulis at depths of 5 to 10 m. Moreover, anoxia and the presence of sulphide in deep water, which prevented hatching of A. tonsa eggs and decreased the survivorship of older life stages sinking below 20 m depth, further contributed to the low copepod abundance.
Place, publisher, year, edition, pages
2008. Vol. 2, no 1, 93-103 p.
IdentifiersURN: urn:nbn:se:su:diva-15626DOI: doi:10.3354/ab00043ISI: 000259452400010OAI: oai:DiVA.org:su-15626DiVA: diva2:182146
1. Univ Gothenburg, Kristineberg Marine Res Stn, Dept Marine Ecol, S-45034 Fiskebackskil, Sweden
2. Univ Stockholm, Dept Syst Ecol, S-10691 Stockholm, Sweden
3. Roskilde Univ Ctr, Dept Environm Social & Spatial Change, DK-4000 Roskilde, Denmark
4. Univ Copenhagen, Marine Biol Lab, DK-3000 Helsingor, Denmark
5. Aarhus Univ, Dept Marine Ecol, Natl Environm Res Inst, DK-4000 Roskilde, Denmark2008-12-072008-12-072011-01-10Bibliographically approved