Limnological comparison of two peridunar ponds in the Doñana National Park (Spain)

Abstract

The ponds Santa Olalla and Dulce belong to the peridune pond system on the E-W coastline of the Doñana National Park.The water that fills these ponds originates in the groundwater tables of the dunar system, and these ponds also contain rainwater (run-off and drainage). Despite the fact that they are contiguous ponds,which join up during determined periods, they present differences, both in water chemical characteristics and in their phytoand zoo planktonic communities.Santa Olalla shows conductivity values of 3 to lOmS/cm in the dry period, and of 0.5 to 3mS/cm in the rainy one. Its water is sodium chloride enriched. The pH values vary between 7 and 11. It is a hypereutrophic pond with chlorophyll-a at higher concen tration than 100mg/m3 in most of the samples. The phytoplankton community is do minated by Spindina platensis, Anabacnopsis circtdaris, Microcystis aeruginosa, Aphanothece clathrata and Coelospbaerium kuetzingianum. The zooplankton is dominated by Bracbionus plicatilis, Keratella quadrata, Daphnia magna and Acantbocyclops robustus.Dulce presents a lower salinity (conductivity values between 0.8 and 2.5mS/cm in the dry period and between 0.25 and 1.7 in the rainy one) and althouhg it also has sodic chloride enriched water, the proportion of divalent cations is higher than Santa Olalla. The pH values vary between 6 and 9.5. Macrophyte develop in this pond. The phyto plankton community is dominated by Chroococcus dispersas, Merismopoedia punctata, Aphanocapsa elaebista, Kirchneriella microscópica, Monorapbidium spp and Scenedesmus spp. The zooplankton is dominated by Acantbocyclops robustus and Arctodiaptomus wierzejski.

Multigenerational effects of nickel on Daphnia magna depend on temperature and the magnitude of the effect in the first generation

“…Ecological risk assessment is often based on singlegeneration ecotoxicological laboratory experiments that are performed at a standard temperature, which means that the potential influence of temperature on chemical toxicity and effects from multigenerational exposures in the field are not taken into account. Temperature is an important abiotic factor for ectothermic organisms, including the ecotoxicological model organism Daphnia magna, which can be found in ponds and lakes at water temperatures between 5 and 26 8C (Carvalho 1987;Lopez et al 1991). The increase in surface water temperature raises both ventilation and respiration rates and reduces generation time (i.e., time to first brood) of D. magna (Paul et al 2004a;Walsh et al 2014;Bae et al 2016).…”