Response of marine phytoplankton to low levels of arsenate

Phytoplankton species vary widely in their degree of inhibitionto low levels of dissolved arsenate (1 – 10 ? ambient).Similarly, natural phytoplankton assemblages cultivated outdoorsunder ambient temperature and nutrient conditions indicate thatthe observed variance in sensitivity is sufficient to causea marked change in species composition and succession in dosedassemblages relative to controls, again at very low levels ofarsenate. The changes in species that occurred, however, werenot always similar to the response predicted from single–speciescultures. In addition, a species' level of resistance to arsenateis often not comparable with its resistance to other anthropogenicstress. It is therefore questionable whether predictions concerningenvironmental consequences of a given pollutant can be madeon the basis of laboratory bioassays of a single species. ¹Contribution # 4695 Woods Hole Oceanographic Institution²Present address: Academy of Natural Sciences, Division of EnvironmentalResearch, Benedict Estuarine Research Laboratory, Benedict,MD 20612, USA