Ecological survey of endolithic blennies spawning in a sandstone habitat in the Gulf of Trieste

Abstract

          The present research aimed at evaluating the importance of endolithic holes for the spawning of blennies and at studying the selection and utilization of holes by blennies in the Gulf of Trieste. The study was conducted using the all-occurrence sampling method, a non-destructive visual census method, aided by SCUBA. Resident, egg-guarding males of Lipophrys dalmatinus, Lipophrys canevae, Aidablennius sphynx, Parablennius incognitus, Parablennius zvonimiri and Parablennius rouxi were caught. Speciesspecific differences in the utilization of holes were found for species that nest in endolithic holes. Smaller species (e.g. Lipophrys dalmatinus and Lipophrys canevae) choose holes that are little larger than their heads and approximately as long as their body, which prevent small males from being dislodged by bigger ones. Bigger species that are probably less exposed to interspecific competition for holes, choose mostly holes with an entrance diameter twice as big as their head diameter and much longer than their body. Species living in shallow waters (e.g. Aidablennius sphynx) prefer hole positions exposed to daylight, while species living in deeper waters were mostly found in the shade of boulders and rocks.