Freshwater rock pools: a review of habitat characteristics, faunal diversity and conservation value

Abstract

SUMMARY1. In the light of the recent surge of interest in small and often temporary wetlands as model systems for ecological and evolutionary research, this article reviews current knowledge on freshwater rock pools and their fauna. 2. Freshwater rock pools occur all over the globe in all major biomes and depend mainly on precipitation for filling. Rock pool clusters are some of the more persistent and oldest freshwater habitats worldwide. Interactions between climate and geology (e.g. limestone, sandstone, granite) generally determine the morphology and hydrology of rock pool habitats, with hydroperiods ranging from several days up to the whole year. Pool volume is usually small, resulting in strongly fluctuating environmental conditions, low conductivity and wide variations in pH (from 4.0 to 11.0) and temperature (from freezing point to 40°C) often with well-marked diel cycles. The highly variable environmental conditions, combined with the unpredictability of the flooding regime, require high stress tolerance of the inhabitants, with adaptations for surviving the dry phase such as the production of resistant stages and active emigration followed by recolonisation. 3. About 460 aquatic animal species have been recorded from freshwater rock pools around the world. Approximately 170 of these are passive dispersers, which mainly disperse as resting stages via wind and overflow of water between pools. Successful long distance dispersal seems limited. This group is composed mainly of rock pool specialists with a high degree of endemicity. The remaining taxa can be considered active dispersers, with migration usually restricted to the adult stage. Often these taxa are broadly distributed and occur in a wide range of temporary habitats in addition to rock pools. 4. The inherent characteristics of freshwater rock pools, such as their simple structure and occurrence on similar substrata all over the world, facilitate comparison of research results and promote rock pools as model systems for ecological and evolutionary research. Nevertheless, despite their potential as model systems, the unique fauna and their importance as sources of freshwater in dry countries, the ecology of freshwater rock pools remain virtually unexplored in large parts of the world.

A contribution for the limnological knowledge of basaltic knickzones

“…surface area, volume, degree of connection with adjacent running channels, presence of marginal vegetation, quantity of periphyton and fish biomass). Particularly in case of freshwater rock pools the highly variable environmental conditions in such small restricted water volumes, in addition to exposition of seasonal an erratic weather, require high stress tolerance of the biota, with adaptations for surviving the dry phase such as the production of resistant stages and active emigration followed by quick re-colonization (Jocque et al, 2010).…”

Mechanisms determining the fate of dispersed bacterial communities in new environments

“…However, it has previously been shown that similar 'mild' salinity differences can affect microbial communities both in terms of function and composition (for example, Langenheder et al, 2003). Another possibility could therefore be that the rock pool communities were already 'pre-conditioned' to environmental fluctuations, as they regularly experience quite drastic differences in environmental conditions (Jocque et al, 2010).…”

Distribution and assemblages of large branchiopods (Crustacea: Branchiopoda) of northern Western Ghats, India

“…Some parts of the Western Ghats of Maharashtra possess unique and interesting habitats in the form of rocky outcrops (Widdowson and Cox, 1996;Jog et al, 2002) which are generally known to host rich large branchiopod fauna (Pinder et al, 2000;Timms 2006;Brendonck et al, 2010;Jocque et al, 2010). Despite these facts, ecological and distributional studies on the large branchiopod in these parts of Ghats and surrounding areas are rare to the best of our knowledge, with only a few published reports (Pai, 1958;Karande and Inamdar, 1959, 1960, 1964Padhye et al, 2011aPadhye et al, , 2011bPadhye et al, , 2015.…”