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Temporary ponds are unpredictable habitats that exhibit inundation periods of variable duration (hydroperiods). We hypothesised that changes in microcrustacean assemblages, namely among ponds (spatial variation) and within ponds at a monthly scale (intra-annual variation), would differ according to hydroperiod length. We found that the microcrustacean assemblages of the study ponds demonstrated distinctive individual patterns that were dependent on monthly variation. During pond filling, species turnover was particularly high in short-hydroperiod ponds, probably due to the fast hatching of the initial pool of species, which seemed to determine subsequent species succession. Some of the long-hydroperiod ponds were able to hold water during the summer, which meant that they could harbour adult microcrustaceans in the early autumn, in contrast to the recently filled ponds; species turnover could thus increase at the onset of the inundation cycle. In the summer, species turnover decreased (while the contribution of nestedness to β-diversity increased) because only a few tolerant species were able to withstand the poor water quality found in drying ponds. We suggest that preserving the broader hydroperiod gradient, by protecting ponds with different environmental conditions within each hydroperiod category, would safeguard the ecological dynamics of the microcrustacean assemblages found in temporary ponds. [ABSTRACT FROM AUTHOR]

Recent and increasing interest in temporary ponds as biodiversity reservoirs fosters our need to test sampling techniques for characterising their biological communities. We compared the efficiency of dip-netting to that of fyke nets in sampling the macroinvertebrate assemblage of a temporary pond in Doñana National Park (SW Spain). We sampled the pond at four different times-morning, afternoon, evening and night-distinguishing between deep and shallow zones. In our sampling, dip-netting captured a higher number of taxa, and higher abundances of individuals than fyke nets. However, both techniques captured exclusive taxa, not recorded with the other device. Fyke nets distinguished between nocturnal and diurnal macroinvertebrates, and hence are more appropriate to study macroinvertebrate diel activity. We detected nocturnal activity in Gerris thoracicus larvae, and adults of Colymbetes fuscus, Rhantus suturalis, Rhantus hispanicus and Hydrochara flavipes. Conversely, larvae of Sympetrum fonscolombei and Notonecta spp., and adults of Notonecta glauca were mainly diurnal. The overall diel activity pattern of the macroinvertebrate assemblage depended on the diel activities of their integrating taxa and stages. Although dip-netting was more appropriate to sample macroinvertebrate assemblages in different microhabitats, fyke nets better captured nocturnal and fast-swimming invertebrates. Consequently, the joint use of both sampling techniques would capture a better picture of the representative macrofauna of a temporary pond than either one on its own. [ABSTRACT FROM AUTHOR]