Distribution of planktonic ciliates in highly coloured subtropical lakes: comparison with clearwater ciliate communities and the contribution of myxotrophic taxa to total autotrophic biomass

Abstract

1. The planktonic ciliate communities of eleven organically coloured north and central Florida lakes representing a variety of trophic conditions were examined during 1979-80. The total abundance and biomass of ciliates were not significantly different from comparable clearwater lakes and only minor taxonomic replacements were noted at the order level.2. Timing of population peaks of oligotrophic lakes was dissimilar to clearwater lakes of the same trophic state, but seasonality in mesotrophic and eutrophic lakes resembled patterns described for comparable clearwater lakes.3. Various ciliate components were strongly correlated with chlorophyll a concentrations, but only moderately correlated to dominant phytoplankton groups. No significant correlations were found between ciliate components and bacterial abundance.4. Myxotrophic taxa numerically dominated oligotrophic systems, particularly during midsummer, and accounted for a large percentage of the total ciliate biomass. Estimates of the ciliate contribution to total autotrophic biomass indicate that these zoochlorellae-bearing protozoa may account for much of the autotrophic biomass during midsummer periods in coloured lakes, and thus may lead to an overestimation of phytoplankton standing crops available to zooplankton grazers if chlorophyll a is used as a surrogate measure of algal biomass.

The temporal and spatial patterns of protozooplankton abundance in a eutrophic temperate lake

“…Recent years have seen an increase in freshwater protozooplankton investigations from a range of latitudes and across the trophic spectrum of lake types (e.g. Bark, 198 1;Beaver & Crisman, 1982;Beaver et al, 1988;Hecky & Kling, 1981;Pace & Orcutt, 1981;Taylor & Heynen, 1987). There are a number of interesting parallels between freshwater and marine protozooplankton assemblages.…”

A mixotrophic ciliate as a major contributor to plankton photosynthesis in Australian lakes

“…Although the abundance of cells may be comparable to, or lower than, mixotrophic ciliate numbers recorded in eutrophic/mesotrophic northern hemisphere lakes (Beaver et al 1988;Laybourn-Parry and Rogerson 1993), the large size of Stentor and its substantial Chl a content are responsible for the high level of population photosynthesis observed. In some of the northern hemisphere subtropical colored lakes, however, very high abundances of mixotrophic oligotrich ciliates occur (up to 250,000 liter-l) (Beaver et al 1988). By using reported Chl a contents of Strombidium viride (Perriss et al 1994), this equates to -40 pg Chl a liter', which must be playing a substantial role in plankton photosynthetic activity.…”

“…The freshwater oligotrich Strombidium viride, for example, contributed only 0.5% of total carbon fixation in a eutrophic temperate lake (Perriss et al 1994) whereas the marine species Laboea strobilu contributed an estimated average 2% in Georges Bank (NW Atlantic;Stoecker 1991). In some tropical and subtropical lakes, however, the proportion of mixotrophic ciliates (usually oligotrichs) is high, which suggests that mixotrophic ciliates may be contributing significantly to photosynthesis in the plankton (Hecky and Kling 1981;Beaver et al 1988). In a marine study in the Nordic Sea, mixotrophic ciliates occasionally contributed up to 24% of community chlorophyll (Putt 1990).…”

Composition et distribution spatio-temporelle des protozoaires ciliés dans un petit lac hypereutrophe du Cameroun (Afrique centrale)

“…La forte variabilité saisonnière du nombre de ciliés au cours de cette étude implique que de nombreux autres facteurs que la pluie et les ressources, comme la prédation, affectent les peuplement ciliés étudiés (BEAVER et al, 1988;SANDERS et LEWIS, 1988;SIME-NGANDO, 1991;PINEL-ALLOUL et al, 1995;KECKEIS et al, 2003). De plus, le peuplement cilié du Lac Municipal de Yaoundé reflète probablement la qualité des eaux de ce lac (CAIRN, 1978;FOISSNER, 1988;BACK, 1985;DRAGESCO et DRAGESCO-KERNEIS, 1986;NJINÉ et FOTO MENBOHAN, 1998, BONECKER et al, 1997 …”