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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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Effects of artificial lights for ecotourism on little penguins

Effects of artificial lights for ecotourism on little penguins

Wildlife watching is an emerging ecotourism activity around the world. In Australia and New Zealand, night viewing of little penguins attracts hundreds of thousands of visitors per year. As penguins start coming ashore after sunset, artificial lighting is essential to allow visitors to view them in the dark. This alteration of the nightscape warrants investigation for any potential effects of artificial lighting on penguin behavior. It was experimentally tested how penguins respond to different light wavelengths (colors) and intensities to examine effects on the colony attendance behavior at two sites on Phillip Island, Australia. At one site, nocturnal artificial illumination has been used for penguin viewing for decades, whereas at the other site, the only light is from the natural night sky. Light intensity did not affect colony attendance behaviors of penguins at the artificially lit site, probably due to penguin habituation to lights. At the not previously lit site, penguins preferred lit paths over dark paths to reach their nests. Thus, artificial light might enhance penguin vision at night and consequently it might reduce predation risk and energetic costs of locomotion through obstacle and path detection. Although penguins are faithful to their path, they can be drawn to artificial lights at small spatial scale, so light pollution could attract penguins to undesirable lit areas. When artificial lighting is required, it is recommended keeping lighting as dim and time-restricted as possible to mitigate any negative effects on the behavior of penguins and their natural habitat. informacion[at]ebd.csic.es Rodríguez et al (2018) Penguin colony attendance under artificial lights for ecotourism. J Exp Zool https://doi.org/10.1002/jez.2155


https://onlinelibrary.wiley.com/doi/abs/10.1002/jez.2155