Juan Rueda

EFFECT OF EPISODIC AND REGULAR SEWAGE DISCHARGES ON THE WATER CHEMISTRY AND MACROINVERTEBRATE FAUNA OF A MEDITERRANEAN STREAM

Physical, chemical and biological parameters were used to investigate the effects of regular and episodic sewage inputs,either domestic or industrial, on the water quality of a smallMediterranean stream (River Magro, eastern Spain). Although results from chemical analyses were useful for monitoring waterquality in areas where sewage discharge was regular, episodic andlocalised discharges from industries or farms were not detected by chemical analyses because sampling was performed seasonally. An adequately small number of macroinvertebrate taxa were foundto indicate water quality changes within R. Magro, and the presence/absence and relative abundance of these taxa can be usedas a simple, rapid, low cost method for detecting changes in water quality. Macroinvertebrates are highly sensitive to episodic sewage discharges, which are difficult to detect by classical physical and chemical monitoring.

An invaded invader: high prevalence of entocytherid ostracods on the red swamp crayfish Procambarus clarkii (Girard, 1852) in the Eastern Iberian Peninsula

The American red swamp crayfish Procambarus clarkii (Girard, 1852) was introduced in 1973 into the Iberian Peninsula for commercial purposes. As a result of both the expansion from the Iberian Peninsula and, probably, further introductions in other European countries, now it is widely distributed throughout much of Europe. The ecological impacts of this invading crayfish have received increasing attention, but nothing is known about its symbiotic entocytherid ostracods outside the American continent. The present survey has examined more than 200 crayfishes from 12 localities distributed over a wide area of Eastern Spain. Entocytherid ostracods were extracted from individual crayfishes and they were identified, counted, assigned to developmental instars and sexed. In all the study locations but one, we found at least one crayfish individual infected by entocytherid ostracods and the species determined was the same in all cases: Ankylocythere sinuosa (Rioja, 1942). The number of ostracods on individual P. clarkii varied notably in relation to crayfish size and also differed significantly among sampling sites. The crayfish size effects on ostracod densities might be related to the amount of resources and to the crayfish age and moulting frequency affecting ostracod distribution and population structure. In addition, the spatial variation in ostracod densities could also be related to site-specific habitat traits and the variability of crayfish population dynamics. Our study represents the first citation of an alien entocytherid species in Europe and demonstrates its wide distribution in the Iberian Peninsula. Further research is needed to know the potential effects of this ostracod species on the ecology of P. clarkii and of native species, with implications on the management of this aquatic invader.

Endorheic versus karstic lakes: patterns of ostracod distributions and lake typology in a Mediterranean landscape (Castilla - La Mancha, Spain)

In a survey for conservation of non-marine aquatic systems, the ostracod compositions of 43 water bodies sampled in central Spain were analysed by multivariate ordination (DCA) and classification (TWINSPAN) methods, showing a clear division in lake typology. The wide variety of life modes and habitat requirements of non-marine ostracod species yields assemblages of species of value as ecological indicators. Endorheic shallow lakes, highly temporary, are characterized by an assemblage of circum-Mediterranean and endemic species. Karstic and more stable lakes are inhabited by northern Holarctic or Palaearctic species, depending on the history and environmental conditions of the water body. Between these two extremes, the study of ostracod assemblages permits the distinction, on a finer scale, of a gradient of lake types with different disturbance conditions, resulting from a combination of hydrological, climatic, chemical and anthropogenic factors. At the extreme of that gradient, highly tolerant cosmopolitan species play an important role in the ostracod community of sites severely affected by human activities.

Global distribution of Fabaeformiscandona subacuta: an exotic invasive Ostracoda on the Iberian Peninsula?

Although exotic species of Ostracoda have been recorded from various sites in Europe, none of them have a widespread European distribution. Reviews of existing literature, examination of specimens, and sampling in Spain and Japan has greatly expanded the known distribution of the candonid ostracode Fabaeformiscandona subacuta (Yang, 1982). We herein present new reports of its presence in mainland eastern Asia, Australia, and South America, and we review its distribution on the Iberian Peninsula. Although this species is globally widespread, we hypothesize that it is an invasive species on the Iberian Peninsula in light of the following facts: it is not known from other European countries, its known global distribution is extremely disjunct, it has not been found during palaeo-limnological investigations of European lakes, and on the Iberian Peninsula it is almost exclusively found in artificial, intensely human-impacted habitats, mostly in reservoirs and ricefields.

An alien ectosymbiotic branchiobdellidan (Annelida: Clitellata) adopting exotic crayfish: a biological co-invasion with unpredictable consequences

Abstract Invasive alien species present a global threat to biodiversity, particularly where pathogens and symbionts are involved. Branchiobdellidans are clitellate annelids with an obligate ectosymbiotic association primarily on astacoidean crayfish. There are several examples of branchiobdellidan species adopting a geographically exotic host where endemic and exotic crayfishes cohabit the same water body. The first records of a western North American branchiobdellidan, Xironogiton victoriensis, adopting the eastern North American crayfish, Procambarus clarkii, in 2 river basins in Spain provide further evidence of the ectosymbionts’ tolerance to adopt an exotic host. Given worldwide translocations of these and other commercial crayfish species, limnologists and agency managers need to be alert for further introductions of X. victoriensis and other branchiobdellidans. Impacts of these exotic ectosymbionts on habitat and biota at a new location are unknown, as are their consequences on native biodiversity.

Invasion biology in non-free-living species: interactions between abiotic (climatic) and biotic (host availability) factors in geographical space in crayfish commensals (Ostracoda, Entocytheridae)

In invasion processes, both abiotic and biotic factors are considered essential, but the latter are usually disregarded when modeling the potential spread of exotic species. In the framework of set theory, interactions between biotic (B), abiotic (A), and movement-related (M) factors in the geographical space can be hypothesized with BAM diagrams and tested using ecological niche models (ENMs) to estimate A and B areas. The main aim of our survey was to evaluate the interactions between abiotic (climatic) and biotic (host availability) factors in geographical space for exotic symbionts (i.e., non-free-living species), using ENM techniques combined with a BAM framework and using exotic Entocytheridae (Ostracoda) found in Europe as model organisms. We carried out an extensive survey to evaluate the distribution of entocytherids hosted by crayfish in Europe by checking 94 European localities and 12 crayfish species. Both exotic entocytherid species found, Ankylocythere sinuosa and Uncinocythere occidentalis, were widely distributed in W Europe living on the exotic crayfish species Procambarus clarkii and Pacifastacus leniusculus, respectively. No entocytherids were observed in the remaining crayfish species. The suitable area for A. sinuosa was mainly restricted by its own limitations to minimum temperatures in W and N Europe and precipitation seasonality in circum-Mediterranean areas. Uncinocythere occidentalis was mostly restricted by host availability in circum-Mediterranean regions due to limitations of P. leniusculus to higher precipitation seasonality and maximum temperatures. The combination of ENMs with set theory allows studying the invasive biology of symbionts and provides clues about biogeographic barriers due to abiotic or biotic factors limiting the expansion of the symbiont in different regions of the invasive range. The relative importance of abiotic and biotic factors on geographical space can then be assessed and applied in conservation plans. This approach can also be implemented in other systems where the target species is closely interacting with other taxa.

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.