Journal Article

Divergent demographic patterns and perspectives for conservation of endemic species in extreme environments

Bartolini, Fabrizio, Vaselli, Orlando, Aquiloni, Laura, Nuccio, Caterina, Cianfanelli, Simone, Nisi, Barbara

2017

Overview

We studied the distribution, size structure, growth, and diet of the freshwater prosobranch Melanopsis etrusca in experimental and natural population samples. This snail is endemic to isolated headwaters of thermal springs in central Italy. In recent times, several anthropogenic pressures such as water extraction and stream contamination have caused population declines and local extinctions of M. etrusca. Consequently, this species was included on the IUCN Red List of Threatened Species. The streams inhabited by M. etrusca had oligohaline waters; however, some physicochemical variability existed among sites. We found that the two variables most directly related to the patterns of distribution and life history of M. etrusca were water pH and temperature. In particular, individual growth was faster in streams with water temperatures constantly >30°C, which was reflected by a shorter life cycle than in cooler streams (13°–26°C), where snails showed a seasonal pattern of growth. Finally, we observed that individuals in a population that is exposed to extreme temperatures (>35°C) performed a peculiar behavior, spending long periods outside the water. We also found that the diet of M. etrusca reflected the local composition of the periphytic community and was dominated by macrophyte fragments. Our data suggest that heat-adapted populations of M. etrusca hold the greatest potential for recolonization after collapse events. From a conservation perspective, reintroduction programs could be useful to avoid local extinction or bottleneck effects but at the risk of the loss of evolutionary innovations that may have emerged at the population level.

• Publisher: Wiley,Wiley Subscription Services, Inc
• Subject: Annual variations / Anthropogenic factors / Aquatic plants / Biological evolution / Case studies / Composition / Conservation / Contamination / Creeks & streams / demographic patterns / Demographics / Diet / Distribution / Endangered & extinct species / endemic snails / Endemic species / extinction / Extreme environments / Freshwater / Gastropoda / Geothermal springs / Growth / Headwaters / hot spring / Hot springs / indigenous species / Inland water environment / Innovation / Italy / Life cycle / Life cycle engineering / Life cycles / Life history / macrophytes / Marine molluscs / Melanopsis etrusca / Natural populations / Original Articles / pH effects / Population / Population decline / population dynamics / Rare species / Recolonization / Reintroduction / risk / Rivers / seasonal variation / Seasonal variations / Snails / Species / Species extinction / Stream pollution / streams / Threatened species / Water springs / Water temperature / Wildlife conservation