Do seasonal changes in habitat features influence aquatic macroinvertebrate assemblages in perennial versus temporary Mediterranean streams?

Abstract

In this study we examined the importance of seasonal changes in habitat features and aquatic macroinvertebrate responses in temporary and perennial streams from two different catchments in the Western Mediterranean region in Spain. Macroinvertebrate sampling was spatially intensive to account for the relative frequency of meso-(i.e., riffles and pools) and micro-habitats (i.e., different mineral and organic-based substrata) at each site. Samples were collected at two distinctly different phases of the hydrograph: (1) during the flowing period, when poolriffle sequences were well-established, and (2) during the dry phase, when only isolated pools were expected to occur in the temporary streams. During the dry season, both a reduction in the available total habitat and in microhabitat diversity in all sites studied was observed. As a result, taxon richness decreased in all streams, but more dramatically at temporary stream sites and particularly so in the infrequently remaining discontinuous riffles. Macroinvertebrate assemblages differed among catchments (i.e., geographical identity) and sites (perennial vs. temporary). Invertebrate differences were also strong within and among meso-and micro-habitats, particularly mineral and organic microhabitat patches, and differences were due to both loss of taxa from some habitats and some taxa exhibiting certain habitat affinities.

Non-perennial Mediterranean rivers in Europe: Status, pressures, and challenges for research and management

“…Initial floods following wildfires enhance runoff and erosion rates in burned terrains, causing elevated sediment and phosphorus concentrations in receiving downstream water bodies (Blake et al, 2010). Finally, studies that focused on the relative vulnerability of PRS and NPRS to anthropogenic stress have shown that habitat changes (García-Roger et al, 2011) and agro-industrial pressures ) exert severe effects on aquatic macroinvertebrates in NPRS, more severe than in comparable PRS.…”

Recent perspectives on temporary river ecology

“…These systems experience excessive water abstraction and their intermittency can be considered primarily artificial. Garcia-Roger et al (2011) studied aquatic macroinvertebrates in several temporary rivers and related temporal changes in the physical habitat to changes in community structure. They quantified and characterised the physical habitat at local (substrata), reach (riffle and pools), and catchment (among streams) scales and found that changes in substrata availability and riffle-pool sequences had an overriding influence on spatial variability in macroinvertebrate assemblages.…”

“…For example, of the different refuge possibilities for aquatic taxa during drying (e.g., hyporheic zone, remnant pools, adjacent ponds, moist organic substrate) what types of conditions are necessary for various species to adequately resist the lethal nature of drying (e.g., see Garcia-Roger et al 2011;Hodges and Magoulick 2011;Stubbington et al 2011)? Conversely, what habitat components of the dry riverbed support the diversity of terrestrial taxa (invertebrates, amphibians, mammals, birds)?…”

Characterizing Precipitation Variability and Trends in the World’s Mediterranean-Climate Areas

“…In aquatic ecosystems, the prolonged dry season leads to reduced summer streamflow, which causes a shift in ecosystem composition from organisms that are well-suited to lotic (i.e., flowing) environments to those well suited to lentic (non-flowing) ones [23,24]. Interannual variability of climate can produce varying flow conditions by the conclusion of the dry season (either flowing or intermittent), which can also cause differences in community composition and structure from one year to the next [25,26]. Spatial analyses have suggested that the distribution of areas having Mediterranean climate characteristics will change with changing global climate dynamics [15], and the persistence of Mediterranean-climate ecosystems are at risk from the increased variability and shifts in precipitation and temperature patterns expected with climate change [27,28].…”