Temporal and spatial variation of an aquatic invertebrate community subjected to avian predation at the Odiel salt pans (SW Spain)

Abstract

We studied the temporal variation in abundance and distribution of invertebrates in the water column in both traditional and industrial salt pans in the Odiel marshes, south-west Spain, in 2001. We selected 12 ponds that were representative of different salinities and stages of salt production. Every two months, invertebrates were sampled within the 0 -20 cm depth range used by foraging waders. We identified 40 taxa, including 30 aquatic and eight terrestrial metazoan invertebrates. Aquatic invertebrate taxa richness and diversity decreased significantly with increasing pond salinity, whereas total biomass showed a non-significant increase. Overall, Artemia parthenogenetica constituted 67.6 % of invertebrates by number, and 95.5 % of the biomass. The copepod Cletocamptus retrogressus represented 31.1 % of invertebrates by number, and 0.6 % of the biomass. Invertebrate biomass and dominance of A. parthenogenetica was highest in September and lowest in November. There was significant spatial and temporal variation in abundance for all aquatic taxa, and for a given pond and month, the depth, distance to shoreline and fetch (wind effects) all had important partial effects on invertebrate distribution. Ordination methods showed a strong relationship between community structure and water chemistry (salinity, pH and redox potential), with the salinity gradient being the most important. There was a clear separation between low salinity ponds with fish and submerged macrophytes and other ponds. The more intensively managed industrial salines held lower densities and biomass of invertebrates than traditional salines, perhaps owing to greater protection from wind or greater inputs of detritus. The beetle Ochthebius corrugatus was abundant in the tradi-1  2006 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart 200 Marta I. Sánchez et al.tional ponds but absent from the industrial ones. The number of feeding waders using each pond was strongly correlated with the available biomass of invertebrates.

Cestode parasitism in invasive and native brine shrimps (Artemia spp.) as a possible factor promoting the rapid invasion of A. franciscana in the Mediterranean region

“…and examined them for cestode infections. We selected this period because previous studies in the Odiel Saltpans showed that both Artemia abundance and levels of cestode infections reached maxima in the summer and early autumn (Sánchez et al 2006b;Sánchez et al, in preparation). The present study included three populations of the native parthenogenetic A. parthenogenetica and three populations of the invasive bisexual A. franciscana inhabiting salt pond complexes along the Atlantic coast of southern Portugal and Spain (Table 1; Fig.…”

Red and transparent brine shrimps (Artemia parthenogenetica): a comparative study of their cestode infections

“…Artemia parthenogenetica is the dominant invertebrate in the evaporation ponds, where it is a major prey for waders, gulls, flamingos and grebes (Sánchez et al 2006). We used a 0.1-mm mesh net for collecting the sample.…”

Ecosystem services provided by waterbirds

“…For example, hypersaline salt ponds and lakes have unusually low invertebrate species richness and are often dominated by brine shrimp Artemia spp. as the main macroinvertebrate (Sánchez, Green & Castellanos, 2006). However, a diverse community of waterbirds preying on the shrimps maintains up to 15 species of cestodes within the Artemia population, each using a specific waterbird group as final hosts (Georgiev et al, 2005(Georgiev et al, , 2007.…”