Publication Date:
2021-05-19
Description:
1. The analysis of functional groups with a resolution to the individual species level is a basic
requirement to better understand complex interactions in aquatic food webs. Species-specific stable
isotope analyses are currently applied to analyse the trophic role of large zooplankton or fish species,
but technical constraints complicate their application to smaller-sized plankton.
2. We investigated rotifer food assimilation during a short-term microzooplankton bloom in the East
African soda lake Nakuru by developing a method for species-specific sampling of rotifers.
3. The two dominant rotifers, Brachionus plicatilis and Brachionus dimidiatus, were separated to singlespecies
samples (purity 〉95%) and significantly differed in their isotopic values (4.1& in d13C and
1.5& in d15N). Bayesian mixing models indicated that isotopic differences were caused by different
assimilation of filamentous cyanobacteria and particles 〈2 lm and underlined the importance of
species-specific sampling of smaller plankton compartments.
4. A main difference was that the filamentous cyanobacterium Arthrospira fusiformis, which frequently
forms blooms in African soda lakes, was an important food source for the larger-sized B. plicatilis
(48%), whereas it was hardly ingested by B. dimidiatus. Overall, A. fusiformis was, relative to its
biomass, assimilated to small extents, demonstrating a high grazing resistance of this species.
5. In combination with high population densities, these results demonstrate a strong potential of
rotifer blooms to shape phytoplankton communities and are the first in situ demonstration of a
quantitatively important direct trophic link between rotifers and filamentous cyanobacteria.
Description:
Open Access
Description:
Published
Keywords:
Brachionus plicatilis
;
Cyanobacteria
;
Dietary sources
;
Size fractionation
;
Stable isotopes
;
Zooplankton
Repository Name:
AquaDocs
Type:
Journal Contribution
,
Refereed
Format:
pp.1257-1265
