Seasonality of microzooplankton grazing in the northern Wadden Sea

Autor: Martina Loebl, Justus van Beusekom
Rok vydání: 2008
Předmět:
Zdroj: Journal of Sea Research. 59:203-216
ISSN: 1385-1101
DOI: 10.1016/j.seares.2008.01.001
Popis: A sequence of nine dilution experiments was conducted according to Landry and Hassett [Landry, M.R., Hassett, R.P., 1982. Estimating the grazing impact of marine microzooplankton. Mar. Biol. 67, 283–288] in the northern Wadden Sea from March until October 2004 to investigate the seasonality of microzooplankton grazing. From March until April, no grazing was observed. Microzooplankton grazing started in May (0.66 d − 1 ) and increased until August (1.22 d − 1 ). In October microzooplankton grazing was low again (0.17 d − 1 ). Phytoplankton growth rates varied between 0 and 1.1 d − 1 . Since the reliability of dilution experiments is still frequently discussed in literature, we tested if our data obtained by dilution experiments reflected short-term in situ phytoplankton dynamics of the study site. We scaled experimental growth rates to water column irradiance, calculated short-term chlorophyll- a dynamics and compared the results to in situ measured chlorophyll- a concentrations. Calculated chlorophyll- a concentrations correlated significantly with in situ measured chlorophyll- a concentrations but slightly overestimated the in situ measured chlorophyll- a . This overestimation was in the range of phytoplankton assimilation reported for the Wadden Sea benthos. We will show that microzooplankton grazing had a large impact during the Phaeocystis bloom and during summer suggesting that a large proportion of phytoplankton biomass remained the pelagic food web. Microzooplankton grazing did not impact the diatom spring bloom and its demise.
Databáze: OpenAIRE
Externí odkaz: