Seasonal dynamics of macroinvertebrate communities in a semiarid saline spring stream with contrasting environmental conditions

Abstract

Semiarid saline streams are rare aquatic ecosystem types. Their constituent biota is expected to have adapted evolutionarily to strong hydrological variability and salinity stress; however, their ecology is not well known. In this study, we quantify the seasonal changes in the structure of the macroinvertebrate community in the Reventón Rambla (south-eastern Spain), a permanent saline spring stream which is included in a drainage system consisting of ephemeral dry channels (so-called ''ramblas''). Seasonal patterns of community structure were studied in two reaches with contrasting environmental regimes using univariate and multivariate statistics. The upstream site showed more stable environmental conditions than the downstream site, and both sites also differed with regard to species richness, and structural and functional group attributes. On a seasonal basis, community dissimilarity was high during periods when both sites were isolated during summer droughts but dissimilarity decreased when both sites were connected through surface flow. Furthermore, the communities tended to show cyclical trajectories in multivariate ordination space. Rather than being related to salinity stress, these patterns seemed to track the hydrological disturbance regime of this rambla system. Spates tended to disrupt communities, while signs of recovery were evident during low-flow periods. Results suggest that salinity fluctuation does not pose a severe abiotic constraint to these adapted macroinvertebrate communities. Their suits of functional properties provide them with the necessary traits to recover quickly from natural disturbance. While human-caused salinization of streams severely impacts communities eventually reducing their recovery potential, our results suggest that communities in natural saline streams may show similar responses to hydrological disturbance as communities from non-saline streams.

Mediterranean saline streams in southeast Spain: What do we know?

“…Food webs appear to be supported by an important amounts of autochthonous resources as found in other open canopy streams (Gasith and Resh, 1999). Thus, in biomass terms, the most abundant functional feeding groups are gathering-collectors, scrapers and predators, while filtering-collectors and shredders are scarce or even absent (Gutiérrez-Cánovas et al, unpublished results;Moreno et al, 2010).…”

“…Similar, but slightly less accurate models were obtained for Coleoptera (R 2 ¼ 63%), Hemiptera (R 2 ¼ 69%) and the rest of the macroinvertebrate families (R 2 ¼ 70%). Water conductivity, hydrological stability and seasonality appears to be the most important factors determining the aquatic community composition for benthic diatoms (Ros et al, 2009), submerged macrophytes and macroinvertebrates (Gutiérrez-Cánovas et al, unpublished results; Moreno et al, 1997Moreno et al, , 2010Velasco et al, 2006).…”

“…This may be due to their scarcity and scattered geographical distribution, and the low economic value assigned to the environmental services which these systems provide (Moreno et al, 2010). Several reviews dealing with aquatic ecosystems, saline or freshwater, in xeric areas reflect this dearth of knowledge (Gasith and Resh, 1999;Gómez et al, 2005).…”

“…1). These studies highlighted ecological, biogeographical and conservation interests in terms of physical and chemical features (Moreno et al, 1995;Vidal-Abarca et al, 2000, organic matter dynamics (Martínez et al, 1998;Vidal-Abarca et al, 2004), primary production Velasco et al, 2003), life cycles and secondary production (Barahona et al, 2005;Moreno et al, 2008;Perán et al, 1999Perán et al, , 2000, and singularity of both aquatic invertebrates (Gallardo-Mayenco, 1994;Moreno and De las Heras, 2009;Moreno et al, 1997Moreno et al, , 2010Velasco et al, 2006;Sánchez-Fernández et al, 2008), and flora taxa (Aboal, 1986;Aboal and Fletcher, 1996;Moreno et al, 2001;Ros et al, 2009). The response of these systems to some natural and anthropogenic disturbances has been also studied, such as the reestablishment of macroinvertebrate communities after floods (Ortega et al, 1991), and the effects of dilution disturbances on community structure (Velasco et al, 2006) and ecosystem metabolism .…”

Stable isotope composition of the Miocene Dinaride Lake System deduced from its endemic mollusc fauna

“…Extant Pseudamnicola are grazers and deposit feeders (Gofas, 2010), occur in slowly running spring-fed-freshwater bodies and channels (Djamali et al, 2006;Gloer & Zettler, 2007) but also in slightly brackish estuaries and even in saline spring streams (Moreno et al, 2010). The oxygen values in Pseudoamnicola torbariana, however, do not correspond to very negative values as expected for springwater-dwellers, but are outstanding high, ranging around -1.6%.…”