TY - JOUR AU - VaquƩ, Dolors AU - Felipe, Jordi AU - Sala, M. Montserrat AU - Calbet, Albert AU - Estrada, Marta AU - Alcaraz, Miquel PY - 2006/03/30 Y2 - 2024/03/29 TI - Effects of the toxic dinoflagellate Karlodinium sp. (cultured at different N/P ratios) on micro and mesozooplankton JF - Scientia Marina JA - Sci. mar. VL - 70 IS - 1 SE - Articles DO - 10.3989/scimar.2006.70n159 UR - https://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/183 SP - 59-65 AB - An experimental study was carried out to investigate whether two potential predators such as <em>Oxyrrhis marina</em> (phagotrophic dinoflagellate) and <em>Acartia margalefi</em> (Copepoda: Calanoida) had different responses when feeding on toxic (<em>Karlodinium</em> sp.-strain CSIC1-) or non-toxic (<em>Gymnodinium</em> sp1) dinoflagellates with a similar shape and size. Both prey were cultured at different N/P ratios (balanced N/P = 15, and P-limited N/P > 15) to test whether P-limitation conditions could lead to depressed grazing rates or have other effects on the predators. Both predators ingested the non-toxic <em>Gymnodinium</em> sp1, and low or non-ingestion rates were observed when incubated with <em>Karlodinium</em> sp. The dinoflagellate <em>O. marina</em> did not graze at all on <em>Karlodinium</em> sp. at N/P > 15 and very little at NP = 15, as its net growth rates were always negative when feeding on <em>Karlodinium</em> sp. cultured under P-limitation conditions. <em>A. margalefi</em> had lower ingestion rates when feeding on <em>Karlodinium</em> sp. grown at N/P = 15 than when feeding on <em>Gymnodinium</em> sp1, and did not graze on P-limited Karlodinium sp. Nevertheless, feeding on <em>Karlodinium</em> sp. grown under N/P =15 or N/P > 15 did not have any paralyzing or lethal effect on <em>A. margalefi</em> after 24 h. Finally, a direct effect on the viability of <em>A. margalefi</em> eggs was detected when healthy eggs were incubated for 5 days in the presence of <em>Karlodinium</em> sp. grown under N/P =15 or N/P > 15, producing a decrease in viability of 20% and 60% respectively. ER -