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>Zooplankton Grazing during Dinoflagel‐late Blooms in a Cape Cod Embayment, with Observations of Predation upon Tin‐tinnids by Copepods
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Zooplankton Grazing during Dinoflagel‐late Blooms in a Cape Cod Embayment, with Observations of Predation upon Tin‐tinnids by Copepods
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机译：Zooplankton Grazing during Dinoflagel‐late Blooms in a Cape Cod Embayment, with Observations of Predation upon Tin‐tinnids by Copepods
Abstract.The patterns and rates of feeding by the copepodAcartia hudsonicaand larvae of the polychaetePolydorasp. were investigated during the spring in an estuarine embayment. These dominant macrozooplankters fed upon the natural particulate assemblages (predominantly dino‐flagellates) spiked with the toxic dinoflagellateGonyaulax tamarensis. G. tamarensiswas ingested by both zooplankters, as wasHeterocapsa triquetra, the most abundant alternative food item. Ingestion rates generally increased as dinoflagellate concentrations increased, resulting in a relatively constant (and low) filtration rate for each grazer.Dinophysis acuminata, another dominant dinoflagellate, was essentially ungrazed. Thus, the zooplankters did not ingest one dinoflagellate and consumed others in proportion to their availability but at low rates. Based on these low rates and the small number ofA. hudsonicaobserved during the spring, we infer minima! grazing impact on a 1980G. tamarensisbloom. In contrast, the impact of polychaete larvae may have been substantial, since their extreme numerical abundance more than compensated for low filtration rates.In one instance, the tintinnidEutintinnus pectiniswas accidentally included in a grazing experiment. Our ingestion data demonstrate thatA. hudsonica, when presented with a combination of tintinnids and several species of phytoplankton(G. tamarensisandD. acuminata)ingested the tintinnids at high rates, in proportion to their high abundance. Since the nanoflagellateChroomonas amphioxeawas found within the loricae of many of the surviving tintinnids, this also provided a qualitative demonstration of the often‐hypothesized nanoplankton to tintinnid to copepod link in a marine food ch
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