Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster V36
Gudmundur Gudmundsson (1), Anna Stępień (2), Piotr Kukliński (3), Maria Włodarska Kowalczuk (4), Małgorzata Krzemińska (5).
(1) Náttúrufræðistofnun Íslands, (2) Institute of Oceanology, Polish Academy of Science, Sopot
Kynnir / Presenter: Guðmundur Guðmundsson
Tengiliður / Corresponding author: Guðmundur Guðmundsson (gg@ni.is)
Body size is considered as one of the most important adaptation in animals to various external conditions. Size changes along environmental gradients have been widely investigated. The Bergmann’s principle states that within a widely distributed taxonomic clade, animals tend to have larger body size in colder environments at higher latidudes, and likewise smaller body size in warmer regions in lower latitudes. Although there are several exceptions, the Bergmann’s rule is well documented for endothermal animals, and has been found to apply for about 80% of studied ectotherms. However, larger body size with increased water depth in the ocean, (i.e. deep-water gigantism) is also well known, but is not as well understood. Several factors change dramatically with increased water depth (temperature, oxygen, food supply, etc.) and it may thus be expected that organisms have evolved special adaptation to those changing conditions, of which one is often increased body size. In this study, bryozoan zooid size is documented, from shallow to deep waters in the vicinity of Iceland. Bryozoans are colonial organism occurring in a wide range of marine habitats. Their colonies are composed of functional modules called zooids. One colony of bryozoan is often composed of thousands of individuals, providing unique opportunity for measurement replicates. Twelve bryozoan species, with at least four colonies per species, were the subject of this study. The specimens were picked from a suite of 78 samples (from the Bioice project) collected at different water depths (about 50, 100, 200, 300, 500 and 1000m). In each colony, the length and width of 20 randomly selected zooids were measured. The program Permanova was used to test for significant differences in zooid size at different water depths. For ten of the twelve species, the results did not demonstrate any significant bathymetric change in the zooid size. However, two species, Bicellarina alderi and Dendrobeania decorata, produced significantly longer zooids with increased water depths. The results indicate that zooid size in most bryozoan species remains fairly constant with increased water depth.