Mediterranean Ponds Research Articles

Physical, chemical, and management-related drivers of submerged macrophyte occurrence in Mediterranean farm ponds

The construction of ponds for irrigation has proliferated during last decades in Mediterranean regions. If properly constructed and managed, ponds may simultaneously meet conservation and agricultural objectives: the preservation of certain macrophytes might improve water quality for irrigation purposes. However,theeffectsofmanagementareoftenneglected when analyzing the main drivers of organisms commu- nity structure. Here we investigated the effect of environmental variables, construction type and man- agement practices on the occurrence of submerged macrophytes (vascular plants, charophytes,filamentous algae). Total submerged macrophyte coverage and richness did not vary with pond type, but the presence of submerged macrophytes was significantly higher in embankmentponds.Artificialpondsshowedthehighest charophyte richness but lowest vascular plant occur- rence. Total submerged macrophyte occurrence mainly correlated with conductivity and littoral vegetation, whilst the relative importance of environmental factors was higher than variables related to pond type and management.However,embankmentpondsshowedthe highest richness of vascular plants and filamentous algae, and artificial ponds contributed to the regional pool of charophyte species. Thus, construction pond type and management levels might be relevant to understandsubmergedmacrophytesoccurrenceinman- made ponds, since the three pond types contributed to the local and regional species pool.

Parasite host-switching from the invasive American red-eared slider, Trachemys scripta elegans, to the native Mediterranean pond turtle, Mauremys leprosa, in natural environments

The red-eared slider turtle, Trachemys scripta elegans, is among the most over-exploited animals and is still exported annually from the USA all over the world. Once introduced into its new environment, feral populations may arise and pose threats to local biodiversity and ecosystem functioning. In France, it is in fact considered as a risk for the Mediterranean pond turtle, Mauremys leprosa, and the European pond turtle, Emys orbicularis, as they may compete for resources and habitat. Freshwater turtles are also host to a variety of parasites including protozoans and helminths. When introduced turtles escape, parasites may spread to native species. The objective of this study was to document the extent of platyhelminth invasions from T. s. elegans to natural M. leprosa populations in northern Spain and southern France and to evaluate the risks that parasite host-switching may pose on indigenous freshwater turtle species. From DNA barcoding analysis based on the sequencing of the Cytochrome c Oxidase I gene, the Bayesian tree and p-distance comparisons of closely related haplotypes revealed a greater polystome richness within M. leprosa than expected, suggesting that host switching may take place in natural environments. Because these parasites most typically infest American turtles like Chrysemys picta marginata and Graptemys pseudogeographica in their natural home range and because parasites were also found within T. s. elegans feral populations, it is suggested that the red-eared slider would serve as a carrier for a variety of not strictly host-specific polystomes that are transmitted to M. leprosa throughout the south of France. The global trade in freshwater turtles thus provides opportunity for parasites to be transported to new destinations which could impact the physiology, behavior and survival of native turtle species.

The role of charophytes in a Mediterranean pond created for restoration purposes

A small, shallow basin was created and flooded with groundwater in a Reserve Area in Albufera de València Natural Park (AVNP) under the scope of a restoration program intended to mimic typical environments such as freshwater springs, abundant in the past but currently suffering from deterioration (desiccation, pollution, etc.), with the ultimate goal of increasing local biodiversity of submerged macrophytes, particularly charophytes. In this study we have monitored, from April 2009 (a few months after its first flooding) to September 2012, the dynamics of charophyte growth and related physical, chemical and biotic variables to highlight the factors determining charophyte success. Just after flooding, five charophyte species grew spontaneously when oospores germinated in the sediments. Chara hispida populations largely dominated the community and developed dense meadows that covered virtually the entire pond floor. Charophytes exerted a negative influence on phytoplankton densities, increasing water transparency. C. hispida stands precipitated substantial CaCO3 in the form of incrustations on the plants, accompanied by coprecipitation of inorganic phosphorus, maintaining low concentrations of soluble P in the water. Reduced groundwater inflow, increased salinity, nutrient concentration, turbidity and augmented feeding pressure by waterfowl, separately or by synergistic effects, considerably reduced charophyte development during the final year of the study; however, charophytes still represent one of the most extensive and dense stands of submerged vegetation within AVNP, verifying the achievement of the goal of the restoration plan. The knowledge obtained has allowed us to recommend several measures to counteract the decrease of charophytes, which can also be applied in other regions affected by the same stressors.

The response of amphibian communities to fish and habitat features in Mediterranean permanent ponds

Generalized linear models were used to test the effect of fish, using ponds with and without fish and habitat features as covariates, on richness and abundance of amphibian species. Five fish species and six amphibian species were recorded in 60 permanent ponds located in central Italy. The choice of covariates (macrophyte cover and pond surface area) was made after studying the correlations. The richness of amphibian species was not significantly affected by fish presence or macrophyte cover, in line with previous studies, since almost all the fish species were non-predatory. However, abundance of urodeles (newts) was negatively affected by fish and positively affected by macrophyte cover. Although fish may strongly influence the abundance and composition of amphibian communities, the results indicate that the cover of aquatic macrophytes may increase the available habitat for amphibians and therefore their abundance. Anuran species preferred ponds where fish were present, since both groups preferred larger ponds. Concordance between fish and amphibian species composition was not found by the Mantel and Partial Mantel tests. This indicates that the fish assemblages do not predict which amphibian species occur in the pond.

Fatty acids as a tool to understand microbial diversity and their role in food webs of Mediterranean temporary ponds.

Temporary Mediterranean ponds are complex ecosystems which support a high diversity of organisms that include heterotrophic microorganisms, algae, crustaceans, amphibians and higher plants, and have the potential to supply food and a resting place to migratory birds. The role of heterotrophs at the base of the food web in providing energy to the higher trophic levels was studied in temporary ponds in Central and Southern Portugal. The relative quantification of the hetero and autotrophic biomass at the base of the food web in each pond was derived from the polar fatty acid (PLFA) composition of seston through the application of the matrix factorization program CHEMTAX that used specific PLFA and their relative proportion as markers for e.g., classes of bacteria, algae and fungi. The species composition of the culturable microbial communities was identified through their fatty acid profiles. The biomass in the lower trophic level of some ponds presented an even proportion of auto to heterotrophic organisms whilst either bacteria or algae dominated in others. In a selected subset of ponds, the incorporation of bacterial fatty acids was observed to occur in potentially herbivorous zooplankton crustacean. Zooplankton consumed and incorporated bacterial fatty acids into their body tissues, including into their phospholipids, which indicates that energy of heterotrophic origin contributes to the aquatic food webs of temporary ponds.

Modelling Favourability for Invasive Species Encroachment to Identify Areas of Native Species Vulnerability

We assessed the vulnerability of the native Mediterranean pond turtle to encroachment by the invasive red-eared slider in southern Spain. We first obtained an ecogeographical favourability model for the Mediterranean pond turtle. We then modelled the presence/absence of the red-eared slider in the Mediterranean pond turtle range and obtained an encroachment favourability model. We also obtained a favourability model for the red-eared slider using the ecogeographical favourability for the Mediterranean pond turtle as a predictor. When favourability for the Mediterranean pond turtle was high, favourability for the red-eared slider was low, suggesting that in these areas the Mediterranean pond turtle may resist encroachment by the red-eared slider. We also calculated favourability overlap between the two species, which is their simultaneous favourability. Grids with low overlap had higher favourability values for the Mediterranean pond turtle and, consequently, were of lesser conservation concern. A few grids had high values for both species, being potentially suitable for coexistence. Grids with intermediate overlap had similar intermediate favourability values for both species and were therefore areas where the Mediterranean pond turtle was more vulnerable to encroachment by the red-eared slider. We mapped the favourability overlap to provide a map of vulnerability of the Mediterranean pond turtle to encroachment by the red-eared slider.

The role of historic and climatic factors in the distribution of crustacean communities in Iberian Mediterranean ponds

Summary We studied 140 freshwater ponds in eastern Spain spanning a wide range of water source, hydroperiod and regional heterogeneity attributable to orographic and climatic differences. Our aim was to provide a typology for Mediterranean ponds using crustacean assemblages and to find key environmental thresholds that define these pond types. To search for the environmental variables that define these communities, two complementary analyses were used: correspondence analyses (CA) and multivariate regression trees (MRT). We found a high level of specificity of crustaceans defining the different pond types. Three ponds, which were not associated with any of the large set of environmental variables used, were clearly separated from the rest in the CA. These held a very specific and probably relict community, characterised by the large calanoid Hemidiaptomus: we refer to these as ‘Hemidiaptomus’ ponds. Taxonomic information suggests a fundamental influence of historical events. The MRT analysis applied to the rest of the ponds allowed us to create a hierarchical order of several current environmental factors that account for their crustacean community composition. Thus, we defined four further pond types. The most important factor structuring communities was hydroperiod, separating temporary ponds, mainly fed by rain, from permanent ponds, fed from more stable sources. Climate‐related factors subsequently separated two groups of temporary ponds: (i) temporary ponds in semi‐arid areas (mean rainfall <600 mm year−1, spring rainfall <150 mm), which contained Neolovenula alluaudi and (ii) temporary ponds in semi‐humid areas, which contained Mixodiaptomus incrassatus. Amongst the permanent ponds, (iii) lowland coastal spring‐fed ponds with quite constant temperatures hosted a singular crustacean community that was well separated from that found in (iv) inland mountain ponds consisting of more ubiquitous crustaceans. These results provide a typology of ponds useful for conservation planning and freshwater biodiversity maintenance. Moreover, the identified ecological thresholds should be helpful in predicting the communities to be expected as a result of changes to land use or climate.

Pleurodeles waltl Newt Larvae Diet Regarding Available Prey: Choice or Mere Coincidence?

Vernal pools are preferred breeding habitats for numerous amphibian species. The analysis of prey composition during the amphibian larval stages is necessary to understand diet composition and food choice in aquatic communities. We studied the diet of larvae of Pleurodeles waltl when exogenous feeding begins and throughout the flooding period in an episodic Mediterranean pond. The stomach contents were analyzed and the diet was compared to the availability of prey in the pond. The diet analysis revealed an ample diversity of prey, the most abundant being cyclopoid and calanoid copepods and podocopid ostracods. Changes in the composition of the diet corresponded principally to the variations in the availability of different prey as a consequence of the succession of the zooplankton community throughout the flooding period. However, certain taxa such as large anostracans, small anomopods, and turbellarias were not consumed although they were available and abundant. In contrast, prey scarcely represented in the pond such as coleopteran, dipteran, and hemipteran larvae were efficiently captured, suggesting their accessibility to newt larvae. The proportion of prey found in stomachs with respect to their abundance in the pond increased with larval size, coinciding with a reduction in number and bio-volume of available prey. The results suggest that newt larvae are opportunistic feeders and that breeding success of newts may be highly dependent on early egg-laying to match the abundant food supply found at early flooding stages of vernal pools.

Nutrient dynamics in water and sediment of Mediterranean ponds across a wide hydroperiod gradient

In Mediterranean ponds, summer drought enhances seasonality whose intensity varies along topographic and climatic gradients. The alternation of wet and dry periods in rain dependent ponds affects their biogeochemistry and differentiates them from ponds fed by more stable water sources, such as groundwater springs. Superimposed onto this, land use is also a very strong factor of variability. In this study we compared nutrients and organic matter concentrations, in water and in sediment, among different types of Mediterranean ponds based on the source of water, hydroperiod and land use. Forty-three ponds were sampled in Eastern Spain corresponding to five pond types: (1) permanent spring ponds in lowlands, (2) permanent spring ponds in mountains, (3) semi-permanent rain ponds, (4) temporary rain ponds with long hydroperiod and (5) temporary rain ponds with short hydroperiod. The results of this study indicate relevant differences among these pond types. The temporary rain ponds with short hydroperiod are characterized by high turbidity due to suspension of sediment particles rich in phosphorous adsorbed onto them (argillotrophic aquatic systems). They are used for watering domestic sheep that enhance sediment suspension by trampling. Total phosphorous (TP) concentrations in the water are high (like those of hypertrophic lakes), but planktonic chlorophyll a is very low and not correlated with TP, because of the low P-bioavailavility in the water. At the other extreme, we have permanent ponds in lowlands fed by groundwater springs. They are heavily loaded with nitrates due to the surrounding intensive agriculture. In these and other permanent/semipermanent ponds chlorophyll is highly correlated with TP. Sediment characteristics provide a good indication of the hydroperiod, since desiccation has important effects on biogeochemical transformations. A threshold of 5% organic matter (OM) in the sediment separates temporary ponds with a short hydroperiod from those with a long hydroperiod, and a threshold of 8% separates the later from the semi-permanent and permanent ponds. Besides OM reduction, important loss of N occurs during desiccation through mineralization, ammonia volatization and the sequential nitrification/denitrification pathway. On the other hand, the increase of organic P mineralization in dry sediments does not represent a loss of P from the system, since o-P remains adsorbed or bound onto the soil. This leads to a low TN/TP ratio in sediments in temporary ponds with short hydroperiod. These characteristics have to be taken into account when establishing pond typologies and ecological thresholds to assess water quality in these unique aquatic habitats.

How do early successional patterns in man-made wetlands differ between cold temperate and Mediterranean regions?

The early stages of succession in newly created wetlands should be impacted by the region in which the wetland is located, since climate may have filtered the dominant biological strategies of the taxa leading this process and may condition their dynamics. We studied the early successional patterns of macroinvertebrates within man made ponds, located in cold temperate (Scandinavian Peninsula) and Mediterranean regions (Iberian Peninsula), during the first three years following their creation. We predicted (1) non random subsets of the regional species pool (deterministic assembly) guiding the successional process in cold temperate wetlands, and random (stochastic) assembly in the Mediterranean region; (2) higher successional rates in Mediterranean ponds than in the cold temperate ponds, with contrary episodes of highest and lowest change throughout the year; and (3) a significant difference in the composition of biological traits between regions, due to the dominance of traits adapted to hydrological variability in the Mediterranean region. Hypotheses on community structure (1) and the composition of dominant biological traits (3) were mostly supported – deterministic assembly mechanisms in the cold temperate ponds and stochastic assembly in the Mediterranean ponds; and a dominance of different biological traits between regions, explained by the need to overcome hydrological disturbances in the Mediterranean ponds. The dynamics of succession (2) were explained by climatic factors in the cold temperate region but not in the Mediterranean ponds. We suggest that the intrinsic hydrological variability of Mediterranean lentic systems may be a major factor driving community changes in man-made wetlands in this region. In order to generalize the observed patterns, we performed a meta-analysis of the temporal trends of taxonomic distinctness parameters of other successional studies across a latitudinal gradient in Europe, which supported the differences we had observed between latitudinal extremes.

Ultrastructural study of spermiogenesis and the spermatozoon of Acanthocephaloides incrassatus (Molin, 1858) (Acanthocephala, Paleacanthocephala, Arhythmacanthidae) from Anguilla anguilla (Pisces, Teleostei) in Urbino ponds (Corsica Island)

This study deals with first ultrastructure features of Acanthocephaloides incrassatus (Paleacanthocephala, Arhythmacanthidae), a parasite of the fish Anguilla anguilla, reported for the first time in a Mediterranean pond. The spermiogenesis of A. incrassatus shows original specificities which have never been pointed out to this day in ultrastructural studies on spermiogenesis: the centriolar derivative is divided into two parts of different densities: an electron-dense, and the other, electron-lucent; a ring form has been observed on each side of the axoneme; a centriole with one central element. After the elaboration of a flagellum of 9+2 pattern, the centriole migrates in a nuclear groove. Rapidly, the centriole disappears. Then, the flagellum migration occurs by a series of processes and gives rise to a spermatozoon. The spermatozoon of A. incrassatus presents its own specificities: it exhibits an evolution of the centriolar derivative characterized by only nine peripheral elements deprived of a central element in the anterior part, then nine peripheral and one central element, and finally, nine peripheral elements with two central elements. An assumption is emitted on a probable correspondence of the evolution of the derivative centriolar during the spermiogenesis and the evolution that occurs in the spermatozoon. Protein granules also show different sizes and forms, full or emptied of their contents compared with data on other Acanthocephala.

Seasonal changes in tissue nutrient concentrations of macroalgae and aquatic angiosperms in Mediterranean ponds (North-Western Spain)

Seasonal changes in tissue nutrient concentrations of macroalgae and aquatic angiosperms in Mediterranean ponds (North-Western Spain)

Effects of salinity and water temporality on zooplankton community in coastal Mediterranean ponds

Some of the predicted effects of climate warming in Mediterranean climate are the increase of temperature, change of precipitation patterns and the rise in sea levels. This will have major consequences, mainly in coastal aquatic ecosystems, by the increase of salinity and the reduction of the flooding period, affecting the whole aquatic community. To assess on the possible consequences of the global change in the zooplankton community of Mediterranean coastal lakes, we analized the zooplankton diversity in a set of lakes with different salinity and water permanence time. The ponds were classified in four groups: permanent and temporary freshwater ponds, and permanent and temporary brackish ponds. Whereas we did not detect a great effect of hydroperiod on zooplankton community, the increase in salinity produced (through direct and indirect interaction) a rise in rotifer density and a reduction in cladoceran cumulative richness, richness per visit and diversity. All these differences were remarkable in Permanent Brackish lakes, the group which showed the higher dissimilarity with the other groups of lakes. The disappearance of cladocerans in these systems can lead to an increase in the eutrophication and a reduction of diversity.

Chemical interferences when using high gradient magnetic separation for phosphate removal: Consequences for lake restoration

A promising method for lake restoration is the treatment of lake inlets through the specific adsorption of phosphate (P) on strongly magnetizable particles (Fe) and their subsequent removal using in-flow high gradient magnetic separation (HGMS) techniques. In this work, we report an extensive investigation on the chemical interferences affecting P removal efficiencies in natural waters from 20 Mediterranean ponds and reservoirs. A set of three treatments were considered based on different Fe particles/P concentration ratios. High P removal efficiencies (>80%) were found in freshwater lakes (conductivities < 600 μS cm −1). However, a significant reduction in P removal was observed for extremely high mineralized waters. Correlation analysis showed that major cations (Mg 2+, Na + and K +) and anions (SO 4 2− and Cl −) played an essential role in P removal efficiency. Comparison between different treatments have shown that when increasing P and Fe concentrations at the same rate or when increasing Fe concentrations for a fixed P concentration, there exist systematic reductions in the slope of the regression lines relating P removal efficiency and the concentration of different chemical variables. These results evidence a general reduction in the chemical competition between P and other ions for adsorption sites on Fe particles. Additional analyses also revealed a reduction in water color, dissolved organic carbon (DOC) and reactive silicate (Si) concentrations with the addition of Fe microparticles.

Assessment of eutrophication effects on charophytes in Mediterranean ponds (North-Western Spain)

The distribution of charophyte vegetation in 57 ponds located in the basin of the River Duero in North-Western Spain was studied in relation to eutrophication. A total of 11 charophyte taxa were recorded in 40 ponds. However, only Chara fragilis Desv., Chara connivens Salzm. ex A. Braun and Nitella translucens (Pers.) C. Agardh were found in more than 17% of the ponds where charophytes occurred. Significant differences between ponds with and without charophytes were found for the following parameters: volatile suspended solids (VSS), total suspended solids (TSS), turbidity, chlorophyll-a, nitrate and total phosphorus (TP). These variables were significantly lower in ponds where charophytes were present. Charophytes were found over a wide range of TP concentrations (20―6884 μg L ―1 ). However, taxa showed differing sensitivities to phosphorus concentrations. Thus, Chara connivens and Chara fragilis showed the highest optimum values for TP concentration (1875 and 551 μg L ―1 TP, respectively) while Nitella translucens registered the lowest optimum value for TP (69 μg L ―1 ). The charophyte cover showed a significant negative correlation with VSS and chlorophyll-a. As for charophyte taxa, Chara connivens cover was positive and significantly correlated with orthophosphate (SRP), while Nitella translucens cover showed a significant negative correlation with TP and TSS. The ordination of charophyte taxa showed a principal gradient of mineralization and ecological condition and a secondary gradient of eutrophication.

The relative importance of natural and anthropogenic effects on community composition of aquatic macrophytes in Mediterranean ponds

To detect when changes in response to stressors are occurring, biomonitoring programs require an understanding of shifts in biota that occur in response to anthropogenic and natural effects. Aquatic plants are expected to reflect the environmental conditions of ponds and, according to the European Water Framework Directive, macrophytes should be considered in ecological status assessments of inland surface waters. We assessed the relative importance of natural and anthropogenic impacts on submerged, emergent and floating-leaved macrophytes in 44 ponds in Duero river basin (North Iberian Plateau). Constrained canonical ordinations included 15 taxa of submerged macrophytes and 24 species of emergent and floating-leaved macrophytes. Although the proportion of variation explained by all selected variables was relatively low (37%), we found that submerged community composition reflected the influence of natural (habitat and biotic variables) and anthropogenic effects. However, emergent and floating-leaved macrophytes were not influenced by biotic variables. Variance partitioning showed that degradation category was the best predictor of both submerged macrophytes and emergent and floating-leaved macrophyte composition. However, submerged macrophytes were more affected by chemical variables, whereas emergent and floating-leaved macrophyte composition was best explained by land-use variables. The results of this study support the use of macrophyte communities as effective indicators of the ecological status of Mediterranean ponds.

Effects of the intense summer desiccation and the autumn filling on the water chemistry in some Mediterranean ponds

The objective of this research was to compare the effects of evaporation and total desiccation, as well as the infiuence of the rate of refilling, on the concentrations of major ions and nutrients (nitrogen and phosphorus) in Mediterranean ponds. Water level fiuctuations in these ecosystems can have a decisive role in community structuring and functioning and may affect their conservation values. The results obtained enable an assessment of the consequences of water quality changes resulting from the increased evaporation, drastic fiuctuations in water levels and higher incidence of droughts in summer. Desiccation was observed to cause an increase in the bicarbonate and chloride concentrations, whilst sulphate content was frequently found to have decreased. With respect to nutrients, a drastic reduction in water volume increased orthophosphate levels, with a consequent drop in the N-nitrate: SRP ratio. Pond refilling following total desiccation resulted in higher total anion content, especially among the waters with higher mineral content, the extent of which was related to the rate of refilling. When refill followed desiccation, sulphate concentrations increased the most, whilst alkalinity decreased in most ponds. An increase in chloride concentration was only observed when refilling occurred slowly. Orthophosphate and nitrate concentrations increased at the start of the refilling period, although the most pronounced increase was in nitrate which, together with potassium, was probably washed into the ponds through soilleaching following autumn rainfall.

Simulation model comparing the hydroperiod of temporary ponds with different shapes

Simulation model comparing the hydroperiod of temporary ponds with different shapes A model of the water dynamics for shallow, small and temporary Mediterranean ponds has been developed taking into account the annual patterns of rainfall and potential evaporation, pond parameters (pond area, depth and shape) and watershed param- eters (watershed area and saturated water content of the soil). This model predicts the amount of water retained in the pond in real time and therefore, when a pond is going to dry out. It is then possible to calculate how much water will remain in the pond after raining or the number of days per year that the pond is going to be dry. Analyses have been performed for different shapes of ponds and sensitivity of the state variables, at different values for the parameters. The most interesting result of our simulations is that the amount of water in the pond (as % of the total) strongly depends on pond shape and maximum depth and saturated water content of the watershed. Watershed area of the pond will only be important for low intensity rain regimes and for soils with very low saturated water content. Also, the number of days without water (per year) depends on shape and maximum pond depth. Deeper ponds will dry at a slower rate (and therefore have more days with water a year and consequently shorter drought periods) than shallower ones, independently of their area or the total amount of water. A conical pond should have more days with water for the same amount of rain, unless the pond does get totally full in each rainfall episode. Around the Mediterranean Basin, most temporary ponds have a certain degree of articiality (because of agriculture or farms). Thus, this model could help in controlling the hydroperiod by conveniently modifying shapes and depth of ponds to manage and preserve different species or biotic communities. The simulation model used is freely available from the authors or in: http://personales.upv.es/∼algarsal/temporary ponds.zip.

Morphologic and Cytochemical Characteristics of Blood Cells from the European Pond Turtle (Emys orbicularis) and the Mediterranean Pond Turtle (Mauremys leprosa)

ABSTRACT Blood smears from European pond turtles, Emys orbicularis, and Mediterranean pond turtles, Mauremys leprosa, were evaluated to study their morphological and cytochemical properties. We performed morphological studies staining the smears with May-Grunwald-Giemsa and Quick panoptic. We studied cytochemical properties using stains for acid phosphatases, alkaline phosphatases, peroxidases, α-naphthyl acetate esterase, chloroacetate esterase, toluidine blue, and periodic acid-Schiff. We identified and described seven types of blood cells: erythrocytes, thrombocytes, basophils, eosinophils, heterophils, monocytes, and lymphocytes. Morphological and cytochemical properties of thrombocytes, lymphocytes, and monocytes were variable and inconsistent; therefore, these techniques were unable to characterize properly all blood cell types.

Conservation diagnosis of reintroducing Mediterranean pond turtles: what is wrong?

AbstractThe presence of the Mediterranean pond turtle Mauremys leprosa in the Ebre Delta (Catalonia, north‐east Spain) is well documented after the late 1970s, when the first reptile distribution lists were published. Owing to the fact that the species was considered scarce, a reintroduction programme based on the release of individuals at sites with potential habitat suitability was launched. From 1999 to 2001, 234 turtles of different ages were released and subsequently monitored until 2007, in order to make a conservation diagnosis using five assessment criteria. These criteria were body condition, individual growth, reproduction, survival and population growth rate. Despite the relatively large number of turtles released, no viable population resulted from the programme. Assessment criteria suggested that: (1) released individuals showed good physical condition and satisfactory growth (the only positive results); (2) reproduction was almost absent; (3) local survival was reduced compared with that of Spanish wild populations of the species; (4) temporary emigration was high; (5) the growth rate of the population was negative. In conclusion, the results suggested that the habitat at the Ebre Delta marshes may not be favourable to the species, and that the scarce historical data record may indicate a relatively low‐quality habitat; the few records may correspond to individuals dispersing from the river, a more suitable habitat. Thus, we conclude that historically scarce records may be the result of natural patchiness and heterogeneous distributions, and they are not necessarily a good indicator of relict, decimated populations. Good assessment criteria, as those proposed and used here, are necessary tools to assess results in reintroduction projects to recover endangered chelonian populations.