Einfluss von abiotischen Umweltbedingungen auf die frühen Entwicklungsstadien von Phyl- lodoce maculata L.

Abstract

The Wadden Sea a habitat with extreme variability of abiotic factors. In spring, green gelatinous egg capsules of the polychaete Phyllodoce maculata can be found attached to the sediment, algae or hard substrates. The eggs and the newly hatched larvae have to be resistant against multiple changes of abiotic factors in their habitat. In this study we investigate the influence of changes in the abiotic environment on the early deve- lopmental stages of P. maculata. We tested their reaction to changes in salinity, drought, light conditions, and temperature. We show that the egg capsules and the larvae are resistant against changes in temperature and lighting conditions. The embryos inside the egg capsules and the larvae can tolerate decreased salinity in the sea water of up to 50% for at least 48h. Further decrease in salinity leads to increased lethality of embryos and larvae. In larvae inside the egg capsules, dry conditions lead to further development of the larvae, but the larvae seem to be compromised. For free-swimming larvae, drying out is lethal. Additionally, we show that the early stage trophophora larvae are positively phototactic and prefer open water over sediment.