Drawing the line at neglected marine ecosystems: Ecology of vermetid reefs in a changing ocean

Vermetid mollusks form reefs that protect coasts from erosion, regulate sediment transport, serve as carbon sinks, and provide habitat for many fish and invertebrates. This biogenic habitat is found in tropical, sub-tropical, and warmtemperate coastal areas, such as Bermuda, oceanic islands in Brazil, and Hawaii, several locations within the Caribbean and the Mediterranean. These reefs are functionally similar to tropical coral fringing reefs but are built by gregarious vermetid gastropods cemented by a crustose coralline algal species, which probably triggers their settlement. Some descriptive studies in different regions worldwide and comparisons among tropical and Mediterranean reefs contributed to show their important role as engineered habitat and biodiversity hotspots. In recent years, a dramatic decrease in the vermetid live cover was recorded in the Eastern basin of the Mediterranean, with some documented local extinctions within a few decades. Pollution and the spread of invasive species are potential threats to this animal forest and to the biodiversity it supports. Yet, the response of the vermetid reef to climate change is almost unknown, although recent experiments demonstrated high sensitivity of this snail species to ocean acidification. Hence, the ongoing rapid environmental change and increasing anthropogenic use along the coast may have detrimental effects on the remaining reefs and therefore significant ramifications for coastal systems in the Mediterranean and subtropical and warm-temperate regions. This chapter aims at filling these knowledge gaps by presenting both a short literature-based study and a set of new research paths to explore and improve conservation and research activities given the range of ecosystem services pristine vermetid reefs may provide.