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Naddafi, Rahmat
Publications (2 of 2) Show all publications
Naddafi, R., Pettersson, K. & Eklöv, P. (2008). Effects of the zebra mussel, an exotic freshwater species, on seston stoichiometry. Limnology and Oceanography, 53(5), 1973-1987
Open this publication in new window or tab >>Effects of the zebra mussel, an exotic freshwater species, on seston stoichiometry
2008 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 53, no 5, p. 1973-1987Article in journal (Refereed) Published
Abstract [en]

We examined the effect of the zebra mussel, Dreissena polymorpha, an exotic species, on seston stoichiometry by conducting laboratory experiments in which we varied nutrient composition of seston and mussels over time. Zebra mussels altered the stoichiometry of seston through removal of particulate organic nutrients and changed the stoichiometry of the dissolved nutrient pool through nutrient excretion. Grazers had stronger effects on carbon : phosphorus (C : P) and nitrogen (N) : P ratios than on the C:N ratio of seston. Elemental residence time in tissue and high mass-specific nutrient excretion by small mussels caused small mussels to be more efficient nutrient recyclers than larger mussels. Zebra mussels reduced P availability through enhancing C: P and N: P molar ratios of seston during the period extending from June to August, when P was limited in the lake, and increased the C:N molar ratio of seston in June, when N was at the minimum level in the lake. C: P and N: P molar ratios for zebra mussel tissue were higher in August and somewhat in September than in all other months. N was retained more efficiently than P in Dreissena tissue. Nutrient mass-specific uptake rate was higher than excretion rate by zebra mussels.

Place, publisher, year, edition, pages
American Society of Limnology and Oceanography, 2008
National Category
Ecology Fish and Aquacultural Science
Identifiers
urn:nbn:se:uu:diva-96408 (URN)10.4319/lo.2008.53.5.1973 (DOI)000259356000024 ()
Available from: 2007-11-14 Created: 2007-11-14 Last updated: 2024-04-25Bibliographically approved
Naddafi, R., Pettersson, K. & Eklöv, P. (2007). The effect of seasonal variation in selective feeding by zebra mussels (Dreissena polymorpha) on phytoplankton community composition. Freshwater Biology, 52(5), 823-842
Open this publication in new window or tab >>The effect of seasonal variation in selective feeding by zebra mussels (Dreissena polymorpha) on phytoplankton community composition
2007 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 52, no 5, p. 823-842Article in journal (Refereed) Published
Abstract [en]

To investigate the impact of zebra mussels (Dreissena polymorpha) on phytoplankton community composition, temporal variability in selective feeding by the mussels was determined from April to November 2005 in a natural lake using Delayed Fluorescence (DF) excitation spectroscopy. Selective grazing by zebra mussels varied in relation to seasonal phytoplankton dynamics; mussels showed a consistent preference for cryptophytes and avoidance of chlorophytes and cyanobacteria. Diatoms, chrysophytes and dinoflagellates responded differentially to zebra mussel grazing depending on their size. Analysis of excreted products of the zebra mussels revealed that in addition to chlorophytes and cyanobacteria, phytoplankton >50 μm and very small phytoplankton (≤7 μm) were largely expelled in pseudofaeces. The zebra mussel is a selective filter-feeder that alters its feeding behaviour in relation to phytoplankton composition to capture and ingest high quality phytoplankton, especially when phytoplankton occur in preferred size ranges. Flexibility of zebra mussel feeding behaviour and variation in susceptibility among phytoplankton groups to mussel ingestion indicate that invading zebra mussels could alter phytoplankton community composition of lakes and have important ecosystem consequences.

Keywords
Delayed Fluorescence, Lake Erken, phytoplankton dynamics, selective feeding, Zebra mussel
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-96406 (URN)10.1111/j.1365-2427.2007.01732.x (DOI)000245987200005 ()
Available from: 2007-11-14 Created: 2007-11-14 Last updated: 2017-12-14Bibliographically approved
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