Inorganic skeleton of the demosponge Halichondria panicea. Seasonality in spicule production in the Baltic Sea |
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Authors: | C H L Schönberg D Barthel |
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Institution: | Carl von Ossietzky Universit?t Oldenburg, FB7-Zoologie, Postfach 2503, D-26111 Oldenburg, Germany, DE Institut für Meereskunde an der Universit?t Kiel, Abteilung Meeresbotanik, Düsternbrooker Weg 20, D-24105 Kiel, Germany, DE
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Abstract: | Seasonality in spicule production of the demosponge Halichondria panicea (Pallas, 1766) was studied in the Western Baltic from July 1992 to July 1993. Spicule production increased in parallel with
increasing temperatures in spring, being most pronounced during summer after release of larvae. Large proportions of up to
30% immature spicules occurred in the population during skeleton production peaks, and this resulted in reduction of mean
spicule dimensions by ≃20%. Effects on spicule width were more obvious than on spicule length. In winter, when wave forces
were largest, higher percentages of mineral skeleton were observed: 50% of dry weight compared to 40% in summer. Enhanced
spicule densities in the tissues were not attained by marked spicule production but through a reduction in organic content
by shrinking. In spring, growth of body tissue was faster than the build-up of skeleton, so that the relative amount of the
latter was reduced. The indirect, growth-related developments of the skeleton were inversely proportional to temperature and
directly to salinity, silicate concentrations and wave energy. Spicule size and the number of immature spicules were correlated
with temperature and only slightly with salinity. No correlation with oxygen concentration or pH could be detected.
Received: 3 April 1997 / Accepted: 8 August 1997 |
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