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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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Adaptation to high-altitude habitats in the Eastern honey

Adaptation to high-altitude habitats in the Eastern honey

The Eastern honey bee Apis cerana is of central importance for agriculture in Asia. It has adapted to a wide variety of environmental conditions across its native range in southern and eastern Asia, which includes high?altitude regions. Eastern honey bees inhabiting mountains differ morphologically from neighboring lowland populations, and may also exhibit differences in physiology and behavior. The genomes of 60 Eastern honey bees collected from high and low altitudes in Yunnan and Gansu provinces, China, were compared to infer their evolutionary history and to identify candidate genes that may underlie adaptation to high altitude. Using a combination of F_ST?based statistics, long?range haplotype tests, and population branch statistics, several regions of the genome were identified that appear to have been under positive selection. These candidate regions were strongly enriched for coding sequences and had high haplotype homozygosity and increased divergence specifically in highland bee populations, suggesting they have been subjected to recent selection in high altitude habitats. Candidate loci in these genomic regions included genes related to reproduction and feeding behavior in honey bees. Functional investigation of these candidate loci is necessary to fully understand the mechanisms of adaptation to high?altitude habitats in the Eastern honey bee. The results of this research will be very useful to monitor the populations of Asian bees and establish conservation priorities. Pollination services provided by bees are essential for food production throughout the world, but Asian bee populations in China have been declining since the early 20th century due to changes in agricultural practices and the introduction of non-native bees. Therefore, it is important to understand how populations of this species adapt to different environmental conditions such as altitude, as this can help improve conservation efforts and management. informacion[at]ebd.csic.es: Montero-Mendieta et al (2018) The genomic basis of adaptation to high-altitude habitats in the Eastern honey bee (Apis cerana). Mol Ecol DOI 10.1111/mec.14986.


https://www.ncbi.nlm.nih.gov/pubmed/30576015