Diatoms in daphnid culture and bioassay

Abstract

AbstractFor daphnids, the diatom Nitzschia frustulum is both a nutritionally desirable food and a source of essential organics not adequately provided by several green algae commonly fed daphnids in bioassays. Although a diet based on only one alga, Chlamydomonas reinhardti, generated more progeny per individual Daphnia pulex, progeny from broodmates fed diets differing only in that they also included diatoms were consistently more tolerant in acute toxicity bioassays. Feeding studies and bioassays were done in wholly defined inorganic media (MS system) that had contributed all essential inorganic nutrients for more than 100 consecutive generations of test daphnids. This limited the possibility of misinterpretation due either to deficiencies resulting from the absence of essential inorganics or to variations in media. Algae were grown in wholly defined inorganic media, versions of A‐MS (algal version) that were similar to animal media excepting that additional N, P and Si, and the three vitamins (B12, thiamine, biotin) known to be needed by many algae were included.