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Good Reasons and Guidance for Mapping Planktonic Protist Distributions

100%

Bulit C.

Acta Protozoologica

2014

vol. 53

issue 1

Analysing the spatio-temporal distribution of protistan microplankton has faced both conceptual and technical difficulties. However, recognition of a need to study planktonic patchiness, application of a major geology-based methodology (geostatistics) to ecology, and advances in computational technologies have widened the interest in this topic and made it more assessable. This review provides methodological and conceptual guidance on the application of geostatistics to microplankton analysis, using ciliates as example model organisms. Applying geostatistical analysis (and complementary methodologies) to the distribution of ciliate and phytoplankton reveals that attributes of their populations and assemblages (e.g. abundance, biomass, production, diversity) are patchily distributed at multiple spatial-scales in different aquatic environments, and these change over time. Data examined from several environments and scales exhibit distinct patterns of patches regarding their shape, density, and structure; these data can then be used to suggest a behavioural niche-separation of ciliates and the influence of patchiness on the rate processes of food webs. Throughout the review, basic guidance is provided for interpreting where, when, and why planktonic ciliate are so distributed, and directions for work on patchiness is offered, including a guide to the main literature on the topic. This should, therefore, be a useful stepping-stone for researchers interested in the impact of patchiness on protistan ecology, regardless of the environment.

Insights on Short-term Blooms of Planktonic Ciliates, Provided by an Easily Recognised Genus: Cyrtostrombidium

51%

Bulit C., Macek M., Montagnes D. J. S.

Acta Protozoologica

2013

vol. 52

issue 1

Planktonic ciliates occasionally form brief rapid increases in numbers (blooms) that can be trophically important. Although model simulations and mesocosm studies indicate that blooms occur over 10 to 20 days, field data are rarely suffi ciently detailed to reveal their occurrence and demise. Our data (collected over 57 weeks across a coastal lagoon) offer insights into the population dynamics of a single species, place these in the context of the entire ciliate assemblage, and provide guidance on what should continue to be examined. Specifically, to evaluate population dynamics we examine two species of Cyrtostrombidium, characterise temporal and spatial variation of their abundance, and relate these to abiotic phenomena and biological factors. This is also the first report of Cyrtostrombidium in a tropical coastal lagoon. Collectively our analysis reveals key aspects of the dynamics of this genus: 1) small-scale peaks in abundance are ~30 m in size and can persist for ~10–30 days, reaching a maximum of 100 cells ml–1; 2) these increases are driven by biotic factors (revealed through autocorrelation analysis); 3) long-term trends are driven by the shift between dry and rainy seasons and by the periods of isolation of lagoon from the sea (revealed through multiple regression analysis); 4) blooms may at times control primary production; 5) conjugation, an ecologically important event, may be associated with blooms (at times 9% of population was conjugating); and 6) dinoflagellate parasitism, poorly described in oligotrichs, is potentially important in population demise. These results both reflect on how ciliates may behave in short-term events and should encourage the continued need for detailed observations of field samples at a high taxonomic resolution.

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2 Acta Protozoologica

1 2014

1 2013

2 Bulit C.

1 Macek M.

1 Montagnes D. J. S.

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Good Reasons and Guidance for Mapping Planktonic Protist Distributions

Insights on Short-term Blooms of Planktonic Ciliates, Provided by an Easily Recognised Genus: Cyrtostrombidium