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Marine Ecology Progress Series

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MEPS 349:213-225 (2007)  -  DOI:

Nucleic acid levels in copepods: dynamic response to phytoplankton blooms in the northern Baltic proper

Elena Gorokhova1,*, Anna Edlund2, Susanna Hajdu1, Elena N. Zhivotova3

1Department of Systems Ecology, Stockholm University, 106 91 Stockholm, Sweden
2Södertörn University College, 141 89 Huddinge, Sweden
3Department of Ecology and Systematics of Invertebrates, Voronezh State University, 394693 Voronezh, Russia

ABSTRACT: We examined changes in nucleic acids and concomitant population development of the copepods Acartia bifilosa and Eurytemora affinis in relation to the progress of the phytoplankton spring bloom in the northern Baltic proper. Individual RNA and DNA concentrations and their ratios in female copepods as well as copepod abundance and population structure were analyzed in 2 coastal areas that differed in the degree of eutrophication and phytoplankton development. During the study period (February to June 2002), bloom conditions were evident, with chlorophyll (chl) a values being 42% higher in the eutrophic area than in the reference area. In both areas, diatoms dominated; in the reference area, they were replaced by dinoflagellates toward the end of the bloom. Copepod RNA-DNA concentrations increased rapidly at the onset of the bloom and gradually decreased thereafter. Moreover, in the eutrophic area, both copepods had higher RNA content and RNA:DNA ratios throughout the study period, suggesting higher productivity in this area. In both species, we found positive correlations between RNA-based indices and chl a. Thus, as suggested by RNA dynamics, growth rates of A. bifilosa and E. affinis appear to respond rapidly to both temporal variation in spring phytoplankton stock and spatial variation due to the magnitude of the bloom. In addition, we found that species-specific RNA dynamics and RNA--chl a relationships differed between species, indicating possible differences in feeding preferences and growth potential.

KEY WORDS: Biochemical indices · Growth conditions · Population development · RNA and DNA content · Spring phytoplankton bloom

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Cite this article as: Gorokhova E, Edlund A, Hajdu S, Zhivotova EN (2007) Nucleic acid levels in copepods: dynamic response to phytoplankton blooms in the northern Baltic proper. Mar Ecol Prog Ser 349:213-225.

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