Growth rates of natural tintinnid populations in Narragansett Bay

Abstract

Natural microzooplankton populations were pre-screened through 202 pm mesh to remove larger predators and incubated in situ for 24 h in lower Narragansett Bay. Growth rates of tintinnid ciliates were calculated from changes in abundance; experiments were conducted at weekly intervals for 2 yr. Growth rates ranged from 0 to 3.3 doublings d-l; annual minima and maxima in growth rates occurred during the summer. Temperature regulated maximum species growth rates, while net community growth rates were primarily influenced by food quality and availability. Growth rates were depressed during blooms of small, solitary centric diatoms (Thalassiosira) and the antagonistic flagellate Olisthodiscus luteus, in agreement with previous laboratory studies. Excluding experiments when these phytoplankton were abundant, tintinnid growth rates increased asymptotically with nanoplankton (< 10 pm and < 5 wm) biornass and production rates. Smaller tintinnid species showed higher maximum growth rates. Nine species exhibited maximum growth rates which equalled or exceeded 2.0 doublings d-l, and 11 other species exceeded 1.0 doubling d-l. Their high abundance and rapid growth suggest that tintinnids were important grazers of nanoplankton and rapidly entered food webs in Narragansett Bay.

Grazing of phototrophic nanoplankton by microzooplankton in Narragansett Bay

“…The summer decline is due to the toxicity of the flagellate Olisthodiscus luteus to tintinnids (Verity & Stoecker 1982). The winter minimum reflects reduced food availability and growth rates at low temperatures (Verity 1985(Verity , 1986. Tintinnid abundance was not significantly different (p < 0.05) from the 3 yr mean for another site in lower Narragansett Bay, and was comparable to that observed in other shallow coastal waters (see summary in Verity 1984).…”

“…A major problem is that confinement in bottles results in the demise of ciliate populations (Venrick et al 1977). Dialysis bags, on the other hand, have been used successfully to measure grazing and growth rates of natural microzooplankton communities (Landry & Hassett 1982, Verity 1986). …”

Heterotrophic protists as a trophic link between picocyanobacteria and the pearl oyster Pinctada margaritifera in the Takapoto lagoon (Tuamotu Archipelago, French Polynesia)

“…evidenced that the cyanobacteria Synechococcus TAK was the most efficient prey to promote its development. Although the ciliate was not abundant in the natural community of protists at the time of our study, it can however be considered as a picoplanktonivorous protist model: its high growth rate (0.19 h -1 ) and short generation time (ca 4 h) are close to those described for other species of scuticociliates (Hamilton & Preslan 1969) and tintinnids (Verity 1986). Additionally, the gross growth efficiency of Protocruzia sp.…”

Tintinnids and rotifers in a northern Mediterranean coastal lagoon. Structural diversity and function through biomass estimations

“…They are either predators or competitors as well as preys, as indicated by correlation analysis and by the occurrence of nanoplankton in Favella cells and of tintinnids inside Synchaeta individuals Our observed data agree with trophic information given by many authors: tintinnids and rotifers are trophic links between net microzooplankton and mesozooplankton populations. In the literature (Hollibaugh et al 1980, Rassoulzadegan & Etienne 1981, Burkill 1982, Andersen & Sorensen 1986, Verity 1986, Fenchel 1987, Bernard & Rassoulzadegan 1993, Laval-Peuto 1993, tintinnids use a large spectrum of food resources such as organic matters, bacteria, pico-and nanoplankton, maximum food particle size being 41 to 46% of the consumer oral diameter (Spittler 1973). Some tintinnids preferably select dinoflagellates (Stoecker et al 1981).…”