Abundance,community composition,size distribution,and production rates of tintinnids in Narragansett Bay,Rhode Island

The abundance of tintinnid ciliates in lower Narragansett Bay was measured at weekly intervals over the period 1980–1982. Twenty-nine species representing nine genera ranged in abundance from 10¹ to 10⁵ tintinnids l^?1. Tintinnopsis was the most numerous genus in terms of numbers of species and individuals. Total abundance increased with water temperature above 6°C, and with nanoplankton chlorophyll a (<10 μm and <5 μm chl a) averaged over the water column. Exceptions occurred during blooms of phytoplankton previously demonstrated to be poor food for tintinnids (Olisthodiscus, Thalassiosira). Tintinnids aggregated near the bottom during periods of low nanoplankton chl a. Abundances and distributions were not correlated with particulate organic carbon. Seasonal changes in length and oral diameter of loricas of individual species were inversely related to temperature. Oral diameter was a more constant feature of lorica morphology than length. Seasonal patterns in the mean oral diameter of the lorica of all species reflected decreases in the oral diameter of individual species with increasing temperature, and changes from small to large species coincident with similar shifts in the size of phytoplankton. The production rate of tintinnids was 3·3 mgCl^?1 year^?1, equivalent to the ingestion of 26% of total annual net primary production and 52% of the estimated production of <10 μm phytoplankton.