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Marine Ecology Progress Series

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MEPS 280:199-210 (2004)  -  doi:10.3354/meps280199

Copepod egg production and hatching success is reduced by maternal diets of a non-neurotoxic strain of the dinoflagellate Alexandrium tamarense

Adrianna Ianora1,*, Jefferson T. Turner2, Francesco Esposito1, Ylenia Carotenuto1, Giuliana d¹Ippolito1,3, Giovanna Romano1, Angelo Fontana3, Cástor Guisande4, Antonio Miralto1

1Ecophysiology Laboratory, Stazione Zoologica A. Dohrn, Villa Comunale 80121 Naples, Italy
2School for Marine Science and Technology, University of Massachusetts Dartmouth, 706 South Rodney French Boulevard, New Bedford, Massachusetts 02744, USA
3Istituto di Chimica Biomolecolare (ICB) del CNR, Via Campi Flegrei 34, 80078 Pozzuoli (Naples), Italy
4Facultad de Ciencias del Mar, Universidad de Vigo, Lagoas-Marcosende, 36200 Vigo, Spain

ABSTRACT: A unialgal diet of a non-neurotoxic strain of the dinoflagellate Alexandrium tamarense strongly modified egg production and hatching success in the copepod Temora stylifera, even though grazing rates were relatively constant over time. Both exponential and stationary cultures of A. tamarense reduced egg production and hatching success, but the effect of stationary cultures on hatching success was dramatic, with egg viability dropping to 0% after 24 h of feeding. HPLC analyses revealed that the A. tamarense clone was non-neurotoxic, with a mean toxin content of about 0.005 fmol per cell, indicating that adverse effects were not due to saxitoxins or neosaxitoxins. 1H NMR analyses also revealed that diatom-derived PUSCAs (polyunsaturated short-chain aldehydes) were not responsible for reduced hatching rates, since these compounds were absent in A. tamarense as compared to the diatom Skeletonema costatum. Extracts of A. tamarense and the diatom-derived PUSCA 2-trans-4-trans-decadienal were also assessed in terms of biological effects on sea urchin embryo cell divisions. A. tamarense did not show anti-mitotic properties, as extracts did not block first-cell cleavage compared to decadienal. However, A. tamarense extracts did block fertilization success when sea urchin oocytes were first incubated for 30 min in extracts and then fertilized, as opposed to S. costatum extracts, which did not affect normal elevation of the fertilization membrane. This is the first report that dinoflagellates produce antiproliferative compounds, other than PUSCAs, that can potentially reduce copepod egg production and hatching success.

KEY WORDS: Dinoflagellate · Copepods · Egg production · Hatching success · Antiproliferate compounds

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