BUSCADOR RECOLECTA

Efforts to conserve the pond network in the Doñana National Park are being threatened by groundwater overexploitation. The dramatic expansion of farming and tourism in nearby areas has caused a severe lowering of the water table, reducing pond hydroperiod length or even instigating pond desiccation. It is important to document the link between groundwater abstraction and pond deterioration with a view to decreasing human pressures on the park and preserving the pond network's singular biodiversity. Here, the gradual deterioration of one of the network's main ponds is described in detail by characterizing vegetation patterns within the pond's basin using orthophotos taken between 1956 and 2019. In the earliest images, the pond contained a wide central area of bare soil during its dry phase. This area was surrounded by reeds and had a line of Tamarix canariensis trees along its southern edge. Starting in 2000, the orthophotos showed the pond's gradual colonization by terrestrial vegetation. In tandem, pond hydroperiod decreased, as did the length of time the pond retained certain depths of water. In recent years, Tamarix trees finally fully invaded the pond's central area, which is surrounded by reeds and has scattered terrestrial bushes and pines. This invasion resulted from the pond's sparse inundation over recent decades, being the cover of trees related to the depth of groundwater, and is a clear sign of pond deterioration. More broadly, colonization by terrestrial vegetation has been observed in approximately 60% of the network's ponds. Colonization of temporary pond basins by terrestrial vegetation can be used as an indicator of deterioration and highlights the need for active restoration and management., Peer reviewed

Wetland ecosystems worldwide are threatened by habitat alteration, climate change and the introduction of invasive species, even within protected areas. Unravelling the reliance of sensitive wetland-dwelling species, such as amphibians, on habitat characteristics is thus essential to identify conservation targets. Here we assess the distribution of genetic diversity of two strongly aquatic amphibians (Pelophylax perezi and Pleurodeles waltl) in association with habitat features across the most extensive, protected wetland of the Iberian Peninsula: Doñana National Park. Despite inhabiting a protected area free from anthropogenic barriers, the genetic diversity of P. perezi and P. waltl is not homogeneously distributed across the wetland, but instead concentrates in core areas, mainly in the northern zone. Both genetic diversity and connectivity (as opposed to genetic differentiation) showed significant positive associations with the area of the breeding sites and the flooded area surrounding the breeding sites within the dispersal potential of either species, that is nearby pond availability. Large water bodies connected to abundant temporary ponds are key for the maintenance of amphibian genetic diversity. Nevertheless, the core populations of our target species, which show markedly aquatic habits, are concentrated in areas colonised by invasive species, which could compromise their long-term viability. Our results highlight that maintaining widely connected arrays of ponds of different hydroperiods, including large breeding sites free from invasive predators and competitors, is paramount for amphibian conservation in Mediterranean wetlands., This research was funded by grants CGL2009-11123 and CGL2012-4044 and Programa Severo Ochoa para Centros de Excelencia en R+D+I (SEV-2012-0262) from Ministerio de Economía y Competitividad, Spain, and grants CGL2017-83131-P and PID2019-104343RB-I00 from FEDER/Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación, Spain., Wirh funding from the Spanish goverment through the "Severo Ochoa Centre of Excellence" accreditation (SEV-2012-0262), Peer reviewed

We examined occurrence patterns over time for aquatic vascular plant species in a major European natural protected area: Doñana National Park (southwestern Spain). We used all available records (1965 to the present) for aquatic vascular plants found in the park's pond network. Information was available for 38 species across 263 sites, including more than 100 ponds that were intensively monitored between 2001 and 2023. Our results show that aquatic vascular plant species began to decline in the last third of the 20th century. Two phases were apparent: 1) an early phase (late 20th century), during which declines in aquatic vascular plant populations were largely provoked by the arrival of an invasive species, Procambarus clarkii, and 2) a more recent phase during which the overexploitation of the aquifer has resulted in many ponds drying up and in shorter flooding periods in the remaining ponds. At present, nine species have disappeared, and 72% of the remaining species have smaller ranges. Our findings suggest that the dramatic local extinction and decline of Doñana's various aquatic plant populations is a consequence of the rapid habitat loss that has occurred in recent decades. Historically, the park's pond network acted as a refuge for many endangered and unique species facing major threats to their survival. Such no longer appears to be the case., The study was funded by the Spanish Ministry for Science and Innovation (project PID2019-104343RB-I00)., Peer reviewed

Aquatic plants may rely on seeds to promote population persistence after severe disturbances, such as droughts. We characterized the seed germination dynamics for three Potamogeton species following seed storage under dry versus submerged conditions. Overall germination levels were highest for P. lucens and, more specifically, were higher after submerged storage (70.4%) than dry storage (56.0%). Overall germination levels were lower for the two other species and displayed a different response to storage conditions; they were higher after dry storage (P. natans: 24.6%; P. pectinatus: 28.1%) than submerged storage (10.8 and 7.1%, respectively). Only P. natans would have likely made a large seed bank contribution as follows: 42.2% of its seeds remained ungerminated and viable after submerged storage, while this figure was 17.4% for seeds that had experienced dry storage. Our results suggest the species differ in their reproductive strategies. Sexual reproduction plays an important role in Potamogeton lucens, adding new individuals to plant populations every year; however, the low viability of the species’ ungerminated seeds suggest its seed bank contribution may be small, rendering it vulnerable to long periods of unfavourable environmental conditions. In contrast, P. natans would likely make a larger seed bank contribution, underscoring the role its seeds may play in population persistence across years. Potamogeton pectinatus may minimally rely on its seeds, which fits with its predominant use of vegetative reproduction in the field. While its seeds might contribute little to population persistence, they may nonetheless promote genetic variability among populations., This research was funded by the Spanish Ministry of Science, Innovation and Universities project number PID2019-104343RB-I00., Peer reviewed