Seasonal patterns in the abundance of E ctopleura crocea ( C nidaria: H ydrozoa) on a shipwreck in the N orthern A driatic

Abstract

Ectopleura crocea is an A nthomedusan hydroid, frequently recorded and abundant on artificial substrates. Here we examine whether the abundance of this species varies seasonally on a shipwreck in the N orthern A driatic at a depth of 10–12 m. Individuals were first found in late autumn when temperatures had dropped below 15 °C, forming scattered colonies composed of a few, small hydranths bearing immature gonophores. Substratum cover and density increased throughout late winter and spring, reaching a peak in April. At temperatures of about 19 °C, colonies were no longer present in June and remained absent throughout the summer. The polyp gut contents comprised mostly crustaceans.

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