Preliminary discussion of the results obtained in Antarctica during the austral summer 1986-1987: plankton ecology and ecotoxicology

• Main Authors: Joiris, C., Overloop, W., Frankignoulle, M., Bouquegneau, J.-M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1988
• Subjects: Ecotoxicology; Plankton; PS; Antarctica; Antarctic; Austral; The Antarctic; Antarc*
• Online Access: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=199151

Making use of the expertise acquired during more than one decade in the North Sea in the fields of general ecology (C cycling, ecological structure) and ecotoxicology (transfer- and accumulation mechanisms of stable pollutants), we started a comparable study of the Antarctic ecosystems. The aim of this study is to test the generality of the concepts developped for the North Sea systems, and to obtain information on Antarctica, where only fragmentary data are available. 1. Plankton ecology. Three zones were recognized, when considering the amount of bacteria in the upper (mixed) layer of the water column: Antarctic water (mean concentration: 9.10 4 bacteria/ml), south of the Antarctic Divergence (17), and sub-tropical water closer to Africa (37). There exist however also differences in cell volume, so that the differences in biomass are less marked: 1.9, 3.7 and 4.0 µg C/l respectively These values are clearly lower than in temperate zones. The relationship between bacterial biomass and phytoplankton biomass (chlorophyll) however shows a ratio very similar to the one of the temperate zones, suggesting a similar role of planktonic bacteria in the recycling of primary production. 2. Plankton ecotoxicology, From the first results of analysis of organochlorines in particulate matter (mainly phytoplankton), it appears that the concentrations of PCBs are high: 0.75 µg / g dry weight, of the same level as in temperate zones. In order to interprate such results correctly, it is however necessary to express them in other units like lipid weight and per volume of seawater. Per volume, the contamination seems more constant, a conclusion already obtained in the North Sea, but lower than in temperate zones. The explanation is that the Antarctic is less contaminated than our regions -as expected- but that the very low biomasses present cause high levels per unit of biomass.