Abundance of autotrophic, mixotrophic and heterotrophic planktonic ciliates in shelf and slope waters

Abstract

During early summer, the density of microplanktonic ciliates in the euphotic zone on Georges Bank (Northwest Atlantic) ranged from 600 to 13 000 cells 1 ' ; in the slope waters to the southeast of the bank, densities ranged from 1900 to 2800 cells 1 ' . Myrionecta rubra, a photosynthetic autotroph ciliate with a reduced algal endosymbiont, numerically comprised an average of 30 % of the microplanktonic ciliate fauna at stations in < 100m depth, but 3 % or less of the ciliate fauna at the deeper stations. Oligotrichous ciliates with chloroplasts are estimated to have contributed 34 O/ O of the ciliate fauna and were abundant at both shallow, unstratified stations on the bank and at deeper, stratified stations on the slope of the continental shelf and in the Gulf of Maine. Overall, about 50 O/O of the ciliates in the euphotic zone contained chlorophyll. At the shallow water stations, 2 species, M. rubra and Laboea strobila (a mixotrophic oligotrich) accounted for over 50 % of the biomass of ciliates with chlorophyll. At an irradiance of 100 pE m % l , M. rubra and L. strobila had photosynthetic rates of 85 and 465pg C fixed c e l l l h l , respectively. During summer, when phytoplankton biomass is low, autotrophic and mixotrophic ciliates may make an important contribution to photosynthesis in the larger size fractions and be an important source of food for larger organisms that rely on high quality, 2 15 to 20 pm food particles.

Prey switching by Acartia clausi:experimental evidence and implications of intraguild predation assessed by a model

“…The experiments indicate that copepods switch towards ciliates when biomasses pass 14 pg C I-' (-13 small ciliates ml-l), and the model simulations indicate stable ciliate biomasses between 1 and 10 ml-'. This is in accordance with observed abundances/biomasses of ciliates in coastal waters, although maximum values may be higher (Stoecker et al 1989, Leakey et al 1993, Nielsen & Kierrboe 1994, Edwards & Burkill 1995, Gismervik 1997b). Furthermore, it may partly explain the high diversity of ciliate species with seemingly identical trophic position In plankton samples, as one species will be hindered in monopolizing resources.…”

Latitudinal pattern of abundance and composition of ciliate communities in the surface waters of the Atlantic Ocean

“…1). A similar abundance of about one thousand cells per liter was reported in the North Atlantic by Stoecker et al (1989). At other sites with M. rubrum, its biomass was lower and corresponded only up to 8% of the biomass of heterotrophic ciliates (abundance up to 60 cells l -1 , Fig.…”

Feeding on protists and particulates by the leptocephali of the worm eels <i>Myrophis</i> spp. (Teleostei: Anguilliformes: Ophichthidae), and the potential energy contribution of large aloricate protozoa

“…The survival of eels through early life might be compromised by any decline in the availability of large protozoa as food for elopomorph leptocephali. Ciliates are common, abundant and widely distributed (Stoecker et al, 1989;Lessard and Murrell, 1996), and are key components of oceanic food webs (Pierce and Turner, 1992). Ciliate abundance and availability might change owing to global climate change and its impact on the world's oceans (Miller et al, 2009).…”