Subterranean aquatic Oligochaeta

Abstract

SUMMARY1. Aquatic oligochaetes appear to be pre-adapted to live in the subterranean environment. However, in the absence of genuine troglomorphic characters, the stygobiotic status of groundwater oligochaetes can currently be inferred only from their exclusive presence in the subterranean environment. 2. Aquatic oligochaetes constitute a diverse and mostly endemic fauna. Of the more than 100 species currently considered to be stygobionts, 60% are known only from their type locality. In the Rhône-Alpes region of France, about 93% of samples taken from caves and galleries were found to contain oligochaetes of which 13 species are classified as stygobionts. 3. Oligochaete biodiversity in aquatic subterranean environments probably originated by both preservation of relict forms and speciation in situ, possibly followed by radiations favoured by heterogeneous and fragmented habitats. Close phylogenetic affinities between some tubificid species from continental waters and the deep sea suggest a marine origin of part of the subterranean oligochaetes. 4. Oligochaetes are well known to promote bioturbation in surface habitats. Similar information on subterranean oligochaetes is scarce, but some evidence suggests notable bioturbation activity also of hypogean species, and they may also play other ecological roles (e.g. as prey and consumers) where present in high densities. 5. Valuable studies to enhance knowledge of subterranean aquatic oligochaetes include continued exploration of a variety of groundwater habitats, phylogeographic surveys that take advantage of molecular methods, analyses of species traits of both stygobiotic and epigean oligochaetes in subterranean environments, and laboratory studies to describe life histories and resolve other aspects of oligochaete biology and ecology.

A tiered framework for assessing groundwater ecosystem health

“…Inherently, these services fall under the functional indicator group of indices. The simplest measure of ecosystem services is to determine the presence or absence (or abundance) of specific taxa that provide services Creuze des Chatelliers et al, 2009). For water quality improvements, the genes or proteins related to microbial functions can be quantified (Groffman et al, 2006).…”

Stygoregions – a promising approach to a bioregional classification of groundwater systems

“…As a result, these groundwaters are naturally unpopulated or stygofauna is scarce1839. Only 15% of the wells investigated were populated by invertebrates (Table 1).…”

The groundwater oligochaetes (Annelida, Clitellata) of Slovenia

“…Nais is a generalist and cosmopolitan genus, living in all epigean waterbodies and frequently in subterranean habi-tats of Italy (PASCALIS project: Lessinian mountains) and Spain (PASCALIS project: Cordillera Cantábrica) Stoch et al 2009;Martin et al 2009;Achurra and Rodríguez 2010). Rhyacodrilus is a large genus consisting of 44 species, of which 17 are subterranean (4 stygophilic and 13 stygobiotic) (Creuzé des Châtelliers et al 2009). Of the 9 species belonging to Rhyacodrilus found in Slovenia, 5 are stygobiotic (4 of them strictly endemic) and 2 stygophilic.…”