Seasonal changes in situ grazing of the mesoherbivores Idotea baltica and Gammarus oceanicus on the brown algae Fucus vesiculosus and Pylaiella littoralis in the central Gulf of Finland, Baltic Sea

The in situ grazing experiments were performed in the shallow water rocky habitat of the northern Baltic Sea during ice-free season 2002. In the experiments the effects of algal species and choice on the grazing of the mesoherbivores Idotea baltica (Pallas) and Gammarus oceanicus Segerstråle were te...

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Bibliographic Details
Published in:Hydrobiologia 2006, Vol.554 (1), p.117-125
Main Authors: JONNE, Kotta, HELEN, Orav-Kotta, TIINA, Paalme, ILMAR, Kotta, HENN, Kukk
Format: Article
Language:English
Subjects:
Algae
Animal and plant ecology
Animal, plant and microbial ecology
Biological and medical sciences
Feeding rates
Fucus vesiculosus
Fundamental and applied biological sciences. Psychology
Gammarus oceanicus
General aspects
Grazing
Herbivory
Idotea
Invertebrates
Marine
Pylaiella littoralis
Shallow water
Synecology
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Summary:The in situ grazing experiments were performed in the shallow water rocky habitat of the northern Baltic Sea during ice-free season 2002. In the experiments the effects of algal species and choice on the grazing of the mesoherbivores Idotea baltica (Pallas) and Gammarus oceanicus Segerstråle were tested. Salinity, temperature, concentration of nutrients in water and macroalgae and net production of macroalgae were considered as random effects in the analysis. The invertebrate feeding rate was mainly a function of the net photosynthetic activity of Pylaiella littoralis (L.) Kjellman and Fucus vesiculosus L. Feeding rate increased significantly with decreasing algal photosynthetic activity. When the two algal species were incubated together invertebrates fed primarily on P. littoralis. Low selectivity towards P. littoralis coincided with its high photosynthetic activity. The presence of F. vesiculosus did not modify the invertebrate feeding on P. littoralis. The results indicated that (1) the grazing on F. vesiculosus depended on the availability of P. littoralis, (2) the photosynthetic activity of algae explained the best the variation in grazing rate and (3) the grazers are not likely to control the early outbreak of filamentous algae in the northern Baltic Sea by avoiding young and photosynthetically active algae. The likely mechanism behind the relationship is that the increased photosynthetic activity of macroalgae coincides with their higher resistance to herbivory.[PUBLICATION ABSTRACT]
ISSN:0018-8158
1573-5117
DOI:10.1007/s10750-005-1011-x