Research undertaken by Julian Evans as part of his doctoral studies challenges the view that the biological diversity of pebble beds is impoverished. Interest in this habitat was sparked by the rediscovery in pebble beds of the Maltese Topshell, a marine snail endemic to the Maltese islands, suggesting that there is more to this habitat than first meets the eye.
To assess the diversity of pebble beds, systematic sampling of this habitat was undertaken at 15 sites around the Maltese islands. The results were astounding: over 60,000 individuals belonging to 360 different species were recorded from a combined sampled area of 16m2, clearly indicating that pebble beds are much more diverse than previously thought.
Over 60,000 individuals belonging to 360 species were recorded from a combined sampled area of 16m2
Around half of the individuals were spirorbid polychaetes – small worms that live in a coiled tube cemented to the pebble surfaces. In terms of species, molluscs (snails and bivalves) and crustaceans (animals with an exoskeleton and jointed legs) that live in the interstitial spaces between pebbles were the most common.
Three new populations of the endemic Maltese Topshell were discovered, confirming the importance of pebble beds as a habitat for this species. In addition, three species of gobies (small bottom-dwelling fish), which had never been previously recorded in the central Mediterranean area, were also found in the studied pebble beds.
Contrary to the prevailing view that pebble beds are impoverished, these findings indicate that they are rich and diverse habitats, having a higher conservation value than generally thought. This, together with the overall rarity of such habitats, suggests that the occurrence of pebble-bed habitats should be taken into consideration when formulating management plans for safeguarding biological diversity in the coastal zone.
Dr Evans’s research was conducted in association with the University’s Department of Biology and supported by a Strategic Educational Pathways Scholarship, part-financed by the EU’s European Social Fund under Operational Programme II – Cohesion Policy 2007-2013 .