Luis Valls

Rice fields as facilitators of freshwater invasions in protected wetlands: the case of Ostracoda (Crustacea) in the Albufera Natural Park (E Spain)

BackgroundPrevious studies have identified rice fields in the Mediterranean region as ‘hot spots’ for the introduction of alien freshwater organisms. Consequently, special attention should be paid when rice fields are located inside or near protected areas for the conservation of native, endangered species. To analyse the relationship between rice field environmental traits and the ecology of aquatic invaders, a study of zoobenthic communities was carried out in July-September 2008 and May-August 2009 in ten rice fields located in the Albufera Natural Park (E Spain), with focus on Ostracoda.ResultsA total of nine ostracod species were found including four considered exotic: Candonocypris novaezelandiae, Stenocypris macedonica, Cypris subglobosa and Hemicypris barbadensis. The presence of H. barbadensis is remarkable, which is recorded for the first time in Europe and S. macedonica in the Iberian Peninsula. A checklist of Ostracoda from Albufera Natural Park is presented, including 11 exotic species, mostly unknown from Holocene sedimentary records. The analysis of ostracod assemblages showed a significant relationship between oxygen content and ostracod species associations, suggesting that their abundance are partially controlled by habitat variables in the rice fields. The exotic species C. novaezelandiae was more abundantly collected in samples with reduced oxygen concentrations, in contrast to other native species whose abundances were lower in such conditions.ConclusionsRice fields in Mediterranean areas present a summer inundation period which is unlikely in natural temporary water bodies in the area and which may facilitate invasion by (sub-)tropical species. Lower proportion of exotic to native ostracods is observed in less disturbed areas compared to rice fields with intense human activities. We emphasize the role of anthropogenic effects in the dispersal and colonization processes of exotic ostracods and their particular strong influence in the protected areas closest to rice fields.

Living and Dead Ostracod Assemblages in a Coastal Mediterranean Wetland

The Mediterranean coast holds a wide and rich variety of wetlands, some of which are protected by international laws, but at the same time have been historically subjected to threatening activities such as agriculture, pollution and aquifer overexploitation. As part of a conservation and restoration project at the Marjal dels Moros coastal wetland (Eastern Iberian Peninsula) we initiated investigations to begin to characterise aquatic environments, and evaluate changes in the system experienced in recent times. To this aim, we collected four seasonal samples at seven points of the Marjal dels Moros wetland, varying in salinity, permanence and other environmental conditions, and studied the recent past (early modern to contemporary remains) and present (living) communities of Ostracoda. We found relatively poor species richness overall, possibly related to the brackish and seasonal character of large parts of the wetland. Of the seven species encountered the most common ostracods were tolerant to these stressing conditions: Heterocypris salina, Sarscypridopsis aculeata, Ilyocypris gibba and Cypridopsis vidua. A comparison of dead and living assemblages showed no significant differences, suggesting that the overall ostracod metacommunity was resilient to the perturbations experienced in the area, despite some particular locations recording notable shifts in their communities during the sampling period.

Helminth fauna of the invasive American red-eared slider Trachemys scripta in eastern Spain: potential implications for the conservation of native terrapins

Abstract In this study we report on the helminth fauna of the invasive American red-eared slider Trachemys scripta in five localities from eastern Spain where this species co-occurs with two native, endangered freshwater turtles, i.e. Emys orbicularis and Mauremys leprosa. In total, 46 individuals of T. scripta were analysed for parasites. Adult individuals of three helminth species were found: the monogenean Neopolystoma orbiculare, the digenean Telorchis solivagus and the nematode Serpinema microcephalus. Telorchis solivagus and S. microcephalus are trophically transmitted parasites of native turtles that probably infected T. scripta through shared infected prey. Neopolystoma orbiculare infects T. scripta in its native Nearctic range and probably survived the overseas shipping of hosts due to the combination of a direct life cycle, long lifespan in turtles and crowding conditions that allowed frequent (re)infections. These findings entail potentially significant conservation consequences that deserve further attention. First, there was a successful spill-back of Telorchis solivagus and S. microcephalus to large invasive populations of T. scripta in the study area, which could eventually increase infection levels in native turtles. Second, the possibility of spill-over of N. orbiculare to native turtles should not be underestimated as this phenomenon has recently been reported in France. Given the pathogenic potential of N. orbiculare, its transference to native turtles could be troublesome.