Growth Rate of Selected Sheet-Encrusting Bryozoan Colonies Along a Latitudinal Transect: Preliminary Results
Climate change driven alterations of sea-water temperature, salinity, acidity and primary production in many coastal regions will probably affect the ecophysiological performance of sedentary organisms. Despite bryozoan ubiquitous and often dominant occurrence in coastal zones there are few studies on their growth dynamics. Here we report growth rates of selected sheet-encrusting bryozoans from four contrasting (in mean annual water temperature) environments: Adriatic Sea (44° N), Baltic Sea (54° N), northern Norway (68° N), and Spitsbergen (78° N). Perspex panels were photographed underwater and colonies’ growth rates analyzed backwards using digital images. We found a negative trend between growth rate and latitude. Congeneric bryozoan species from lower latitudes grew faster: the average growth rate of the cyclostome genus Diplosolen from the Adriatic Sea was 75 mm2 after 5 months (~180 mm2/year) while Diplosolen arctica from Spitsbergen grew only 4 mm2/year. Similarly the average surface area of Microporella arctica individuals after 12 months in northern Norway was 12 mm2 compared to 2 mm2 in Spitsbergen. An exception from this general pattern was Einhornia crustulenta in the brackish environment of the Baltic Sea, which grew relatively rapid for this latitude and water temperature (surface area of up to 657 mm2/month after settlement).
KeywordsBryozoa Growth rates Latitude
The authors wish to thank Dr. Suzanne Williams, Joachim Scholz and an anonymous reviewer for their comments and corrections leading to a more improved manuscript. This study has been completed thanks to a grant from the Polish Ministry of Science and Higher Education (No NN304 404038).
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