Effect of Protection Level in the Hydroperiod of Water Bodies on Doñana’s Aeolian Sands

Abstract

Mediterranean temporary ponds on Doñana's aeolian sands form an extensive system of small dynamic water bodies, dependent on precipitation and groundwater, of considerable importance for biodiversity conservation. Different areas of the aeolian sands have received different levels of environmental protection since 1969, and this has influenced the degree of conservation and the flooding dynamic of these temporary surface waters. We use the Landsat series of satellite images from 1985 to 2014 to study the temporal dynamic of small temporary water bodies on the aeolian sands in relation to the protection level and to distance to water abstraction pressures from agriculture and residential areas. The results show that even with small and ephemeral water bodies optical remote sensing time-series are an effective way to study their flooding temporal dynamics. The protected areas of the aeolian sands hold a better preserved system of temporary ponds, with a flooding dynamic that fluctuates with precipitation. The unprotected area shows an increase in mean hydroperiod duration, and surface flooded, and a decline in hydroperiod variability. This seems to be due to the creation of irrigation ponds and the artificialization of the flooding regime of the natural temporary ponds, that either receive excess irrigation water or dry-up due to the lowering of the groundwater table level. Although a decline in hydroperiod duration of temporary ponds is seen as negative to the system, an increase in hydroperiod of surface waters due to artificialization, or a decline in variability cannot be considered as positive compensatory effects.

How will climate change affect endangered Mediterranean waterbirds?

“…The benefits of changing conditions are already apparent for the Continental European population of black-tailed godwit Limosa limosa limosa with an increasing fraction of their otherwise declining overall population [ 61 ] wintering in southern Spain instead of in traditional wintering areas in West Africa [ 27 ]. In contrast, the steady decline of hydroperiods in our study area [ 2 , 30 , 31 ] has been related to steep declines in several dabbling ducks preferentially selecting deep waters (e.g., common teal Anas crecca , Eurasian wigeon Anas penelope ; [ 26 ], see also [ 8 ] for similar trends in wetlands of Eastern Spain), but also with the disappearance of the diving ferruginous duck ( Aythya nyroca ), which was fairly common in the Doñana wetland complex some decades ago [ 62 ]. There has also been a decline in the common pochard ( Aythya ferina ), and in the red-crested pochard ( Netta rufina ), which were formerly the two most common diving ducks breeding in Doñana, and are currently uncommon breeders [ 63 ].…”

“…Water salinity can also create habitat gradients in wetlands by controlling the abundance and composition of primary producers, and hence food availability for herbivorous species like vegetation gleaners and dabbling ducks [ 33 , 48 , 54 – 56 ]. Moreover, rainfall and climatic factors largely dominate the hydrological regime in this area, particularly within the Doñana wetland complex [ 38 ], with most waterbodies flooding annually due to winter rains and drying up in the summer [ 30 , 31 , 57 ]. As the drying period progresses, waterbodies will become saltier, but also shallower, and hence less suitable for diving birds [ 21 ].…”

“…Seasonal migratory movements may complicate this picture, as wetlands are used at different times by different waterbird species for reproduction, migratory stopover, or winter refuge over the course of their annual cycles [ 28 , 29 ]. Environmental conditions can also fluctuate seasonally [ 30 , 31 ], thus resulting in varying resource and habitat availability for waterbirds throughout the year [ 29 ]. Finally, species co-occurring in space and time throughout the annual cycle may have different conservation requirements [ 32 ].…”

Modeling Biomass Production in Seasonal Wetlands Using MODIS NDVI Land Surface Phenology

“…We have shown that MODIS Global MOD13Q1 NDVI data provides a good source of information for estimating biomass production in a challenging situation-a seasonal marsh characterized by high spatio-temporal variation in precipitation and hydroperiod [55]. While the use of a single image per growth season provided estimates of reasonable quality (39-41% of variance explained in the calibration dataset), modeling the phenological cycle using Land Surface Phenology (LSP) techniques considerably improved the quality and robustness of such estimates (65% and 70% of variance explained using LSP-Maximum-NDVI, in the calibration and the validation datasets, respectively; see also [56]).…”

Fast and Automatic Data-Driven Thresholding for Inundation Mapping with Sentinel-2 Data

“…These seasonal marshes constitute the largest flooded surface in the Doñana wetlands and are breeding and wintering habitat for many species of European water birds [2]. On the aeolian sand deposits that close the mouth of the Guadalquivir River, there is an extensive system of temporary ponds [34]. Ponds range from small ephemeral pools that flood for a few days or weeks in rainy years to a few large permanent fresh-water lakes.…”