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Doñana's water quality, in danger due to intensive agriculture and a poor residual water treatment

Irene Paredes, researcher of the study

Eutrophication is a major cause of wetland degradation worldwide. In recent decades, reductions in nutrient inputs have led to improvements in water quality in many rivers and lakes in central and northern Europe, but long-term trends are less clear in southern Europe. The Doñana Biological Station conducted the first comprehensive study of water quality in Doñana, one of the most important wetland complexes in Europe and the Mediterranean region.

The core area of Doñana is a large shallow, seasonal marsh (UNESCO World Heritage Site—WHS) that floods during rainy, cool winter months, then dries out during the summer. The marsh is fed by three main streams whose catchments are within a Biosphere Reserve but are impacted by greenhouses (for cultivating fruit, irrigated with groundwater), poorly treated urban wastewaters and tourism.

From 2013 to 2016, the research team monitored nutrient and phytoplankton chlorophyll-a (chla) concentrations in surface waters of the Doñana marsh and the three main streams. They quantified changes in greenhouse cover since 1995 using satellite images. Nutrient concentrations in streams were consistently higher than in the marsh, particularly in the Partido and Rocina streams that regularly reached concentrations equivalent to a "bad physico-chemical status" under the EU Water Framework Directive (WFD), and whose catchments suffered a fivefold expansion of greenhouses from 1995 to 2016.

The Partido was the most polluted stream, and the most affected by wastewater effluents, and had particularly high concentrations of NH4+ and NO2? across seasons. Patterns in chla concentrations were less consistent, but streams generally had higher concentrations than the marsh. Nutrient concentrations in spot samples within the marsh largely depended on a combination of evaporation (as revealed by higher stable isotope ?2H values in the water column) and spatial processes (concentrations increase close to stream entry points, where conductivity is lower).

Anthropogenic nutrient pollution in entry streams is a serious problem in Doñana, with extensive stretches too toxic for fish. Reinforcement of policies aimed at reducing nutrient inputs to Doñana are urgently required to meet the biodiversity conservation and environmental objectives for the WHS and WFD, respectively. Paradoxically, the marsh is currently relied upon to purify the water entering from streams.

informacion[at]ebd.csic.es

Referencia: 

Paredes, I., Ramírez, F., Aragonés, D., Bravo, M.A., G. Forero, M., Green, A.J. (2021). Ongoing anthropogenic eutrophication of the catchment area threatens the Doñana World Heritage Site (South-west Spain). Wetlands Ecology and Management. https://doi.org/10.1007/s11273-020-09766-5

Read the full press release (Spanish)


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Noninvasive sampling of saliva for genetic analysis in ecology

Noninvasive sampling of saliva for genetic analysis in ecology

Saliva is a secretion rich in epithelial cells and an excellent source of DNA for genetic analysis. Attempts to identify wild vertebrates from noninvasive samples of saliva have been restricted to searching for food remains recently handled by target species. This approach often requires close tracking of animals, which is unfeasible for most species and may explain why saliva is seldom considered in ecological studies. Authors develop a noninvasive method of collection that combines baits and porous materials able to capture saliva. Its potential in optimal conditions has been reported using confined dogs and collecting saliva early after deposition. Mean DNA concentration in saliva extracts was high (14 ng µl-1), whereas species (85%) and individual identification rates (90%) were as high as, or higher than, those reported for other kinds of noninvasive samples such as hair, urine or faeces. Genotyping errors (2%) and mean genotyping effort (2 replicates) remained at very low levels. The procedure could advantageously allow detection of socially low-ranked individuals underrepresented in faecal or urine samples associated with marking behaviour. Once adapted and refined, this technique could yield high rates of individual identification of wild vertebrates in ecological field studies requiring noninvasive sampling. informacion[at]ebd.csic.es: Lobo et al (2015) A new method for noninvasive genetic sampling of saliva in ecological research. PLoS ONE 10 (10) DOI: 10.1371/journal.pone.0139765


http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139765