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

Abstract

Background: Previous 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 JulySeptember 2008 and May-August 2009 in ten rice fields located in the Albufera Natural Park (E Spain), with focus on Ostracoda.Results: A 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. Conclusions: Rice 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.

Human-mediated dispersal of aquatic invertebrates with waterproof footwear

“…In recent times, the distribution ranges of alien invertebrates have greatly expanded in freshwater systems (Ricciardi 2015). Candonocypris novaezelandiae (Baird 1843) is an exotic ostracod recently discovered in Spain (Valls et al 2014b) and in particular in one of our study systems, lake La Veguilla in La Mancha Biosphere Reserve (Supplementary material S1), so as in other European countries (Scharf et al 2014). Despite this species did not hatch from any of the analyzed boot samples, this does not prevent that in the future C. novaezelandiae could be further dispersed by human activities.…”

Crayfish invasion facilitates dispersal of plants and invertebrates by gulls

“…It has been recorded in North Africa, which shares migratory waterbirds with our study area (Rendón et al., ). It is possible that H. reticulata is native to southern Spain but has been overlooked until now; however, its wide distribution and the common occurrence of exotic ostracods in ricefields (Valls, Rueda, & Mesquita‐Joanes, ) suggest this is most probably a new alien which is potentially invasive in Europe. The abundance of ostracod eggs in gull excreta, plus previous evidence that ostracod eggs can survive gut passage by waterbirds (Brochet, Gauthier‐Clerc, et al., ; Rogers, ; Valls et al., ), suggests that these ostracods are secondarily dispersed by L. fuscus .…”

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“…Figure 3). Mazzin i et al (2014) and Valls et al (2014) revealed the presence of species in waters with 2.38-2.46 mg L -1 (but not specified) and 0.06±0.00-0.17±0.14 mg L -1 phosphate contents, respectively, when we gathered H. salina from water with 0.14-2.48 mg kg -1 inorganic and 0.025-0.23 mg kg (the present study; Külköylüoğlu, 2013) Meisch (2000) stated that Candona angulata prefers slightly salty waters (0.2-14 ‰) and this statement was supported by the ordination of species on site of CI -1 , Na +1 and water temperature in the present study. We have poor information about the ecology of P. fulva.…”