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In temporary ponds, submerged plants have adapted to recurrent periods of drought. These ponds often lack the impact of large herbivores but can harbor large numbers of herbivorous tadpoles. Tadpoles of the Iberian spadefoot toad (Pelobates cultripes) may reach large body size and consume large quantities of macrophytes during their long larval period, which is shortened with risk of pond drying. We conducted a mesocosm experiment to analyze the interplay between hydroperiod and impact of herbivorous tadpoles on the abundance and life history of 3 species of submerged plants common to temporary ponds. We observed differences in growth among plant species resulting in lags in timing of maximum cover, probably related to interspecific competitive interactions. Some plants responded to pond drying with a remarkable increase in the production of flowers. Tadpoles greatly reduced the plant cover, although their impact varied across plant species. Differential plant consumption by these large tadpoles can substantially modify the internal structure and complexity of temporary ponds, and tadpoles can also interfere with plant responses to shortened hydroperiod.

Among invasive species, floating plants have a great impact on aquatic ecosystems, forming dense mats that cause a great alteration of the physical and chemical water features. We experimentally assessed the effect of Azolla filiculoides mats on Mediterranean temporary waters using mesocosms with sediments from an invaded marsh and amphibian larvae from surrounding wetlands. Azolla filiculoides formed a dense mat over the water surface in the experimental tanks, which decreased pH and oxygen concentration, and increased nutrients, nitrogen and phosphorus compounds in the water compared to mesocosms lacking the exotic fern. Macrophyte abundance and richness were reduced under the Azolla mat. Invaded mesocosms also had higher phytoplankton abundance and different zooplankton composition, which was mainly characterized by higher abundance of juvenile copepods. Regarding amphibian development, tadpoles requiring a long developmental period, the western spadefoot toad, Pelobates cultripes, had significantly lower survival in the presence of A. filiculoides (4.8% compared to 60% survival in fern-free mesocosms). For tadpoles of the Mediterranean tree frog, Hyla meridionalis, which develop faster, we did not detect effects on survival, but on body size and physical condition of metamorphs. The formation of A. filiculoides mats produced a deterioration of the trophic web, as it caused most sources to be depleted in 13C and 15N. Primary consumers, tadpoles and zooplankton, were also 13C depleted, although the diet of tadpoles from Azolla mesocosms was mainly composed of the invasive fern. We therefore conclude that A. filiculoides has a negative impact on physical and chemical water features, reduces the richness and biomass of the submerged macrophyte guild and reduces survival and body condition of tadpoles. Overall, A. filiculoides causes substantial deterioration of the food web of the aquatic ecosystem.

Non-native turtles are susceptible to pathogenic infections that may be transmitted to native species. We performed hematological, biochemical, histopathological, and microbiological analyses in two invasive populations of red-eared sliders (Trachemys scripta elegans), which were living alongside native turtle species in southwestern Spain. The red-eared sliders that were captured had a healthy external appearance. However, the histopathological analyses revealed that up to 88% of these turtles had internal pathologies. The most common were hepatic lipidosis and chronic nephritis, which frequently co-occurred with each other or with pulmonary or pancreatic lesions. A high proportion of turtles were susceptible to infections caused by common bacteria in these habitats. We detected Herpesvirus, Mycoplasma spp. and more than 18 Gram-negative bacteria. The high prevalence of disease recorded in the two populations suggests that red-eared sliders are poorly suited to the conditions in their non-native range.

Understanding the movement of individuals across natural habitats is important to determine fundamental aspects of their ecology, from dispersal patterns and habitat selection to interactions with predators, pathogens or conspecifics. Amphibian larvae are key to aquatic systems, playing fundamental roles as both consumers and prey, affecting nutrient cycling and even physico-chemical properties of the water bodies they occupy. Nevertheless, despite an extensive body of literature on most other aspects of their ecology, we know very little about spatial movements of amphibian larvae in their natural habitats, and the little information we have is restricted to lotic systems. Here we use a mark-and-recapture procedure using elastomers to determine movement patterns and microhabitat selection of western spadefoot toad tadpoles (Pelobates cultripes) in two large ponds in southwestern Spain. We observed maximum distances moved by these tadpoles of >67 m and >245 m, depending on the pond. These distances coincided with the maximum cross distance in each pond, suggesting that they could potentially move even farther in larger wetlands. Mean distances moved were 29.7 and 105 m in each pond. We sampled at two, four and nine days after release of tagged individuals, and we observed a stable, not expanding, movement pattern across sampling dates, suggesting that tadpoles resumed normal activity immediately after release. Tadpoles showed preference for deeper and more densely vegetated areas of the ponds, especially associated with plant species such as Ranunculus peltatus and Potamogeton pectinatus

Ample variation in body size is common in vertebrates over extensive geographical distances, or in isolated populations, where effective geographical barriers may cause dwarfism or gigantism. Here we study potential causes of extreme size reduction in continental populations of amphibians within a short geographical distance and in the absence of geographical barriers. Natterjack toads Epidalea calamita in Doñana National Park (Spain) experience up to 2.1-fold difference in body mass in as little as 37 km. Studying six populations divergent in body size, we tested for genetic isolation of the dwarf populations using multilocus genotypes (16 microsatellites), and explored whether populations differ in trophic status (through stable isotope analysis), standard metabolic rate and growth pattern, senescence and age structure (conducting telomere length assays and skeletochronology). We also recorded advertisement calls across populations and experimentally tested for behavioural reinforcement of the body size variation through female preferences. Local dwarfism in these populations occurs in the absence of genetic isolation while maintaining relatively high effective population sizes. Dwarf populations, however, are exposed to drier and warmer climatic conditions, have different trophic status, show lower mass-specific metabolic rate, and male advertisement calls with a higher dominant frequency. Juvenile growth differed among populations, reaching the adult stage at different body sizes. Altogether, our results suggest a significant influence of environmental conditions on the physiology and ecology of the Doñana E. calamita populations, mainly affecting toads between metamorphosis and sexual maturity. Further experimental and genomic studies focusing on these early life stages are necessary to dissect the relative roles of the environment and adaptive genetic differentiation on this phenomenon., This project was funded by Plan Nacional (grant CGL2014-59206-P). LHJ was supported by a predoctoral fellowship (BES-2015-074463) provided by the Spanish Ministry of Economy and Competitiveness.

Phenotypic plasticity allows organisms to improve the match between their phenotype and heterogeneous environments. Theoretical models have argued that costs of maintaining the sensory and response machinery necessary for adaptive phenotypic plasticity are important determinants to the evolution of plasticity. Despite recurrent arguments invoking putative metabolic costs associated with maintenance of cellular machinery, no studies have yet attempted to quantify it from a molecular standpoint. Here we experimentally examine physiological differences across genotypes (sibships) of spadefoot toad larvae with different degrees of plasticity in response to predator cues. We observed marked differences across sibships in developmental, growth and morphological responses to predators, and tested whether increased plasticity was associated with oxidative stress or immune suppression. We observed that more plastic sibships experienced higher antioxidant enzymatic activity when reared in the absence of predator cues, i.e. not expressing their plastic responses. The degree of plasticity was also associated with higher lipid peroxidation and slightly greater granulocyte-to-lymphocyte ratio. Higher antioxidant activity in highly plastic sibships suggests that maintenance of phenotypic plasticity may be linked to energy demanding metabolic processes. Our findings suggest that having the potential to produce plastic responses may incur oxidative and immunological costs. In the long term, such maintenance costs may erode individual fitness and even constrain the evolution of plasticity. To our knowledge, this is the first empirical evidence indicating the existence of a physiological cost to the maintenance of phenotypic plasticity., This study was funded by Ministerio de Economía y Competitividad (grants CGL2012-40044 and CGL2014-59206-P). PB was supported by fellowship F.P.U.-AP2010-5373 from the Ministerio de Educación and by a Marie Curie Fellowship METAGE-797879. Laboratory facilities were provided by ICTS-RBD.

The invasive aquatic fern Azolla filiculoides forms dense mats that shade submerged macrophytes. Here we show that submerged plants of Ranunculus peltatus switch to a different morphotype when shaded by Azolla filiculoides mats. We used outdoor mesocosms to assess the cover of submerged plants in tanks with presence or absence of the exotic fern. In tanks with A. filiculoides mat covering the water surface, the submerged stems of R. peltatus elongated to surpass the dense mat, while their submerged capillary leaves were deteriorated and lost. Once above the Azolla cover, Ranunculus developed an aerial part of the plant of reduced height with erect aerial laminar and thick capillary leaves, which subsequently produced flowers and fruits. The plants with this aerial amphibian morphotype survived for shorter spans and produced fewer flowers than the aquatic morphotypes growing without A. filiculoides mats. We conclude that the morphological plasticity that characterizes R. peltatus allows this species to subsist the adverse transformation of the aquatic environment by the development of Azolla mats.

Invasive species are one of the main causes of amphibian declines worldwide, often through direct predation. Even species or life stages that may not be prone to predation by invasive animals can be affected through alterations of their reproductive behaviour and/or performance. This aspect is less commonly investigated, and may be important for understanding the full impact of invasive species on local amphibian populations. We used laboratory experiments to measure effects of the invasive Eastern mosquitofish (Gambusia holbrooki) on gravid pygmy newts (Triturus pygmaeus) from southern Spain. Gravid newts altered their position in the water column by moving from the bottom of the aquaria to the surface when in the presence of free-swimming mosquitofish, presumably to reduce physical contact with them. Newts also detected and consumed less prey in presence of free mosquitofish. Newts exposed to caged or free-swimming mosquitofish laid fewer eggs than newts not exposed to the invasive species, suggesting that chemical or visual cues alone were sufficient to alter the behaviour of gravid newts. Our results suggest that mosquitofish can reduce the reproductive success of native pygmy newts in the wild, highlighting the need for management efforts to mitigate this impact.

In temporary ponds, seed germination largely determines how well aquatic plant assemblages recover after dry periods. Some aquatic plants have terrestrial morphotypes that can produce seeds even in dry years. Here, we performed an experiment to compare germination patterns for seeds produced by aquatic and terrestrial morphotypes of Ranunculus peltatus subsp. saniculifolius over the course of five inundation events. During the first inundation event, percent germination was higher for terrestrial morphotype seeds (36.1%) than for aquatic morphotype seeds (6.1%). Seed germination peaked for both groups during the second inundation event (terrestrial morphotype: 47%, aquatic morphotype: 34%). Even after all five events, some viable seeds had not yet germinated (terrestrial morphotype: 0.6%, aquatic morphotype: 5%). We also compared germination patterns for the two morphotypes in Callitriche brutia: the percent germination was higher for terrestrial morphotype seeds (79.5%) than for aquatic morphotype seeds (41.9%). Both aquatic plant species use two complementary strategies to ensure population persistence despite the unpredictable conditions of temporary ponds. First, plants can produce seeds with different dormancy periods that germinate during different inundation periods. Second, plants can produce terrestrial morphotypes, which generate more seeds during dry periods, allowing for re-establishment when conditions are once again favorable.

Telomere shortening with age has been documented in many organisms, butfew studies have reported telomere length measurements in amphibians, andno information is available for growth after metamorphosis, nor in wild popu-lations. We provide both cross-sectional and longitudinal evidence of nettelomere attrition with age in a wild amphibian population of natterjacktoads (Epidalea calamita). Based on age-estimation by skeletochronology andqPCR telomere length measurements in the framework of an individual-based monitoring programme, we confirmed telomere attrition in recapturedmales. Our results support that toads experience telomere attrition throughouttheir ontogeny, and that most attrition occurs during the first 1–2 years. We didnot find associations between telomere length and inbreeding or body con-dition. Our results on telomere length dynamics under natural conditionsconfirm telomere shortening with age in amphibians and provide quantifi-cation of wide telomere length variation within and among age-classes in awild breeding population., This work was supported by FEDER/Ministerio de Ciencia, Innovación y Universidades, Spain (grant nos CGL2017-83131-P, CGL2017-83407-P) and Asociación de Amigos de la Universidad de Navarra (predoctoral grant to G.S.-M.).

Invasive species have major impacts on biodiversity and are one of the primary causes of amphibian decline and extinction. Unlike other top ant invaders that negatively affect larger fauna via chemical defensive compounds, the Argentine ant (Linepithema humile) does not have a functional sting. Nonetheless, it deploys defensive compounds against competitors and adversaries. We estimated levels of ant aggression toward 3 native terrestrial amphibians by challenging juveniles in field ant trails and in lab ant foraging arenas. We measured the composition and quantities of toxin in L. humile by analyzing pygidial glands and whole-body contents. We examined the mechanisms of toxicity in juvenile amphibians by quantifying the toxin in amphibian tissues, searching for histological damages, and calculating toxic doses for each amphibian species. To determine the potential scope of the threat to amphibians, we used global databases to estimate the number, ranges, and conservation status of terrestrial amphibian species with ranges that overlap those of L. humile. Juvenile amphibians co-occurring spatially and temporally with L. humile die when they encounter L. humile on an ant trail. In the lab, when a juvenile amphibian came in contact with L. humile the ants reacted quickly to spray pygidial-gland venom onto the juveniles. Iridomyrmecin was the toxic compound in the spray. Following absorption, it accumulated in brain, kidney, and liver tissue. Toxic dose for amphibian was species dependent. Worldwide, an estimated 817 terrestrial amphibian species overlap in range with L. humile, and 6.2% of them are classified as threatened. Our findings highlight the high potential of L. humile venom to negatively affect amphibian juveniles and provide a basis for exploring the largely overlooked impacts this ant has in its wide invasive range.Efectos del Veneno de la Hormiga Argentina sobre los Anfibios Terrestres Resumen Las especies invasoras tienen un impacto importante sobre la biodiversidad y son una de las causas principales del declive y extinción de los anfibios. A diferencia de otras hormigas super-invasoras que afectan negativamente a animales más grandes por medio de compuestos químicos de defensa, la hormiga argentina (Linepithema humile) no tiene unaguijón funcional. Sin embargo, esta hormiga despliega compuestos defensivos contra sus competidores y adversarios. Estimamos los niveles de agresión de las hormigas hacia tres anfibios terrestres nativos exponiendo a los anfibios juveniles en pistas de hormigas en el campo y en las arenas de forrajeo de las hormigas en el laboratorio. Medimos la composición y las cantidades de toxina que presenta L. humile por medio del análisis de las glándulas pigidiales y el contenido en el cuerpo completo. Examinamos los mecanismos de la toxicidad en los anfibios juveniles cuantificando la toxina en el tejido del anfibio, buscando daños histológicos y calculando las dosis tóxicas para cada especie de anfibio. Para determinar el alcance potencial de la amenaza para los anfibios usamos bases de datos mundiales para estimar el número, distribución y estado de conservación de las especies terrestres de anfibios con distribuciones que se solapan con la de L. humile. Los anfibios juveniles que co-ocurren temporal y espacialmente con L. humile mueren al encontrarse con esta especie de hormiga en sus pistas. En el laboratorio, cuando un anfibio juvenil entró en contacto con L. humile, las hormigas reaccionaron rápidamente rociando a estos juveniles con veneno proveniente de las glándulas pigidiales. La iridomyrmecina fue el compuesto tóxico que encontramos en las glándulas pigidiales. Después de ser absorbida por la piel del anfibio, se acumuló en el cerebro, los riñones y el hígado. La dosis tóxica para los anfibios depende de la especie. A nivel mundial, se estima que 817 especies de anfibios terrestres tienen una distribución que se solapa con la de L. humile, y el 6.2% de estas especies se encuentran clasificadas como amenazadas. Nuestros hallazgos resaltan el potencial alto del veneno de L. humile para tener efectos negativos sobre los anfibios juveniles y también proporcionan una base para la exploración de los impactos de esta hormiga en su amplio rango invasivo, los cuales generalmente son ignorados.生物入侵对生物多样性有着重要影响, 同时也是导致两栖动物数量减少和灭绝的主要原因之一。不同于其它通过化学防御物质对大型动物产生负面影响的入侵蚁类, 阿根廷蚁 (Linepithema humile) 不具备功能性的刺, 但它还是可以利用防御化合物来对付竞争者和攻击者。我们通过在野外蚁道和实验室的蚂蚁觅食场所观察蚂蚁如何挑战三种本土陆生两栖动物的幼体, 估计了蚂蚁的攻击性强度。通过分析阿根廷蚁臀板腺体和全身的物质组成, 我们测定了其毒素的成分和含量。通过定量两栖动物幼体组织中的毒素, 寻找组织损伤, 并计算毒素对每种两栖动物的毒性剂量, 我们分析了蚂蚁毒素对两栖动物幼体的毒性机制。接下来, 为了确定两栖动物面临潜在威胁的范围, 我们利用全球数据库分析了与阿根廷蚁分布范围重合的陆生两栖动物的数量、范围和濒危情况。在野外, 与阿根廷蚁时空上共存的两栖动物幼体在蚁道上遇到阿根廷蚂蚁时会发生死亡。在实验室中, 当两栖动物幼体接触到阿根廷蚁时, 蚂蚁会迅速做出反应, 向其喷射臀板腺体毒液。喷射液体中的有毒化合物为阿根廷虹臭蚁素, 动物吸收后会在脑、肾和肝组织中积累, 毒素对两栖动物的毒性剂量取决于物种。在世界范围内, 估计有 817 种陆生两栖动物的分布区与阿根廷蚁分布区重叠, 其中有 6.2% 为濒危物种。本研究的发现强调了阿根廷蚁的毒液对两栖动物幼体潜在的巨大负面影响, 并为探索阿根廷蚁在其广大的入侵范围内尚未得到重视的影响提供了基础。【翻译: 胡怡思; 审校: 聂永刚】 阿根廷蚁毒液对陆生两栖动物的影响.

In Mediterranean temporary ponds, the timing of annual flooding is highly variable and depends on heavy seasonal rains. Ponds can flood in the autumn, winter, or spring, and thus the environmental conditions faced by emerging zooplankton can be very different. We performed an experiment in a climatic chamber where we simulated annual variation in natural temperature and light conditions to study how differences in pond-filling season affected zooplankton assemblage composition. We sampled sediments from a temporary pond and placed them in aquariums that were filled with water during three different seasons: autumn (October), winter (January), and spring (March). Zooplankton abundance, species richness, diversity, and assemblage composition differed significantly among treatments, and post-inundation temperature and pH appeared to be the main drivers of these differences. Diversity was highest in the winter treatment. It was lower in the autumn treatment and the spring treatment, and no indicator species were present in the latter. Our results suggest that interannual variability in initial inundation conditions favours the emergence of different species and thus contributes to high species richness in the egg bank. However, climate change and/or groundwater drawdown could delay pond flooding, impoverishing the zooplankton assemblage in the long term.

Vazquez, L.A., Rendon, M.A., Diaz-Paniagua, C., Gomez-Mestre, I. 2017. Among-species variation in the morphological responses of larval amphibians to native and invasive species. Ecosistemas 26(3): 32-38. Doi.: 10.7818/ECOS.2017.26-3.05 Amphibian larvae are common prey to various types of predators, according to the type of aquatic system they develop in. When they detect water-borne chemical cues from predators (kairomones), amphibian larvae often produce inducible defenses. An important component of such defenses is the alteration of the shape of the larvae, which often consists in producing rounder bodies, shorter tails and deeper tail fins in the presence of predators. However, the activation of these inducible defenses critically depends on the accurate recognition of predator cues. In that context, the human introduction of alien predators with whom local prey species have not shared a joint evolutionary history may pose a grave threat in part because the native prey may fail to recognize the cues of the novel predators and hence fail to trigger the corresponding antipredator phenotype. In this study we analyze the morphological responses of larvae of four amphibian species to two different types of predators: native dragonfly larvae and introduced red-swamp crayfish. We find that three out of the four species readily respond altering their morphology to the presence of dragonflies, but they all fail to respond to introduced crayfish. Moreover, the effect size of the morphological response seems to be congruent with the duration of the larval period of each species so that faster developing species show lesser responses to dragonflies whereas slower developing species show greater responses to them. This is congruent with faster developing species occupying temporary or even ephemeral ponds which typically have lower predator abundance.

Water level changes have been monitored over 25 years in several temporary ponds located at different distances to a pumping area of a tourist resort fringing the Doñana National Park (SW Spain). The numerical model MIKE SHE was set up to simulate pond water levels and hydroperiod fluctuations. It was calibrated for nine hydrological years and validated for two periods of eight hydrological years each to assess whether the duration of the pond wet phase (hydroperiod) significantly deviated from an expected pattern driven by rainfall and evapotranspiration. The model output indicated a satisfactory performance for all simulations. This approach provided two main conclusions: a) a long-term increasing trend in water losses on the pond water balance which has not been followed by a corresponding decreasing trend in rainfall, and b) these water losses were highest in the pond located at < 1 km to the pumping area and lowest in the pond located at a further distance (5.6 km) and at a lower altitude. Our results suggest that, in the long run, a small groundwater abstraction rate has exerted a high hydrological pressure on the closest pond to the pumping area.

Invasive fish have a high disruptive potential in aquatic ecosystems, in which amphibians may be highly impacted due to intense competition and/or predation on their eggs and larvae. Most studies have focused on the effect of large invasive fishes such as salmonids, whereas the effect of smaller fish on amphibians has been seldom investigated. We experimentally studied effects of the invasive Eastern mosquitofish (Gambusia holbrooki) on pygmy newts (Triturus pygmaeus), a species endemic to the Iberian Peninsula. We set up outdoor mesocosms in Doñana National Park with native aquatic flora and invertebrate fauna, and containing larval newts at two experimental densities. Density of larval newts was also crossed with presence or absence of mosquitofish, either free-swimming or caged, in order to distinguish consumptive and non-consumptive effects. Increased density of coexisting larval newts did not reduce their survival, but reduced their growth and development. Newt survival and size at metamorphosis were dramatically reduced in the presence of free-swimming mosquitofish, whether at low or high fish densities. Caged mosquitofish, however, had no effect on larval newts. In laboratory trials, mosquitofish preyed more efficiently on insect larvae than did larval pygmy newts, highlighting the high competitive potential of mosquitofish. This was confirmed by the depletion of zooplankton that free fish caused in the experimental outdoor mesocosms. Our study suggests that invasive mosquitofish exert a high negative impact on coexisting newt populations. Such effects can be explained by a combination of direct predation, injuries caused by predation attempts, and intense competitive exploitation of common food resources., Financial support was provided by the Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Program for Centers of Excellence in R&D&I (SEV-2012-0262, Grant SO-07), and by CONACYT (Consejo Nacional de Ciencia y Tecnología de México; postdoctoral fellowship to ECG: 204202).

Organisms are exposed to multiple environmental factors simultaneously to which they often respond behaviorally, morphologically and/or physiologically. Amphibian larvae are quite plastic and efficiently adjust their phenotype and physiology to the reigning local conditions. Here we tested whether the combination of predator presence and low water pH induces alterations in the morphology and physiology of spadefoot toad tadpoles. We raised Pelobates cultripes tadpoles in the laboratory in water at either pH 4 or 7, and in the presence or absence of caged dragonfly nymphs, and determined their changes in shape through geometric morphometrics to assess whether predator recognition was impaired or not at low pH. We also measured levels of plasma corticosterone, activity of four antioxidant enzymes, as well as markers of oxidative damage and redox status. We found that tadpoles altered their body shape in response to predator cues even at low pH, indicating that predator recognition was not interfered by water acidity and developmental responses were robust even under abiotic stress. Water acidity was associated with increased corticosterone levels in tadpoles, whereas predator presence consistently reduced corticosterone levels. Predator presence was linked to reduced antioxidant enzyme activity, whereas the combination of both factors resulted in negative synergistic effects on lipid peroxidation and the antioxidant capacity of tadpoles. Here we show that tadpoles detect predators even at low pH but that the development of adaptive anti-predatory morphology can magnify physiological imbalances when other stressors co-occur. These results emphasize the need to understand how multiple environmental perturbations can affect animal homeostasis.

In a very dry year, when aquatic habitats were scarce, we observed exceptionally massive corixid oviposition on terrapin shells in Doñana National Park, southwestern Spain. Most terrapins inhabiting a large pond devoid of aquatic vegetation exhibited a dense cover of corixid eggs, whilst terrapins from vegetated ponds had no egg cover. Corixid oviposition had also been observed on terrapin shells in previous periods of severe drought. Considering that terrapins frequently alternate between aquatic and terrestrial environments, we experimentally assessed the viability of corixid eggs in varying degrees of dry-exposure. A significant proportion of corixid eggs did not hatch when they were occasionally dried under sun exposure, but egg mortality was lower when they were dried in the shade. The massive oviposition on terrapin shells was probably a consequence of the limited availability of adequate oviposition sites, and it might increase the odds of egg survival when terrapins migrate to other ponds.

Organisms react to environmental changes through plastic responses that often involve physiological alterations with the potential to modify life-history traits and fitness. Environmentally induced shifts in growth and development in species with complex life cycles determine the timing of transitions between subsequent life stages, as well as body condition at transformation, which greatly determine survival at later stages. Here we show that spadefoot toad larvae surviving pond drying and predators experienced marked alterations in growth and development, and in their fat reserves, oxidative stress, and relative telomere length. Tadpoles accelerated development but reduced growth and consumed more fat reserves when facing pond drying. However, oxidative stress was buffered by increased antioxidant enzyme activity, and telomeres remained unchanged. Predators caused opposite effects: they reduced larval density, hence relaxing competition and allowing faster development and enhanced growth of survivors. Tadpoles surviving predators metamorphosed bigger and had larger fat bodies, increasing their short-term survival odds, but showed signs of oxidative stress and had shorter telomeres. Developmental acceleration and enhanced growth thus seemed to have different physiological consequences: reduced fat bodies and body size compromise short-term survival, but are reversible in the long run, whereas telomere shortening is non-reversible and could reduce long-term survival

Summary: Connections between consumers and resources in food webs are complex and affect the structure and functioning of ecosystems. We assessed the influence of amphibians as consumers on the structure and functioning of temporary ponds, determining their impact on macrophyte abundance, zooplankton diversity and water chemistry. The effect of amphibians may be modulated by interactions with predators or competitors that alter tadpole density or behaviour. Therefore, we also investigated the consumptive and non-consumptive effects of native and invasive predators on amphibian larvae and pond ecosystems. High amphibian density decreased macrophyte biomass and zooplankton diversity and increased water turbidity and nutrient content. These effects were largely attributable to tadpoles of the largest herbivorous species, spadefoot toads (Pelobates cultripes). In the absence of spadefoot toads, amphibians unexpectedly affected plant biomass positively. Invasive crayfish (Procambarus clarkii) altered community structure in similar ways to high densities of amphibians and caused greater mortality of amphibian larvae than did native predators. The high herbivorous impact of spadefoot toads and invasive crayfish carried over to the following hydrological cycle. Copyright © 2014 John Wiley & Sons Ltd599 September 2014 10.1111/fwb.12402 Original Article Original Articles © 2014 John Wiley & Sons Ltd.

We radiotracked individuals of the exotic aquatic turtle Trachemys scripta elegans and 2 coexisting species of native turtles (Mauremys leprosa and Emys orbicularis) in southern Spain. Aquatic home range areas differed among species only in winter, when T. s. elegans moved in larger areas and showed shorter inactivity periods than the native turtles. Differences in these activity patterns may provide an advantage for individuals of the exotic species, which were already moving widely when native turtles started their posthibernation activity and would have been expected to be recolonizing their home ranges in depleted physical condition.

Eggs of the Western spadefoot toad (Pelobates cultripes) reached a 100% mortality in all 29 clutches deposited at a pH below 5.0 in a temporary pond of the Doñana National Park (SW Spain) throughout the wet season of 2006–2007. A similar trend was detected in a neighbouring pond. The proximity of these two ponds to a groundwater pumping area (< 1.5 km), prompted us to elucidate the possible links between the reduction in pond hydroperiod over past decades (1989–2008) and the decrease of groundwater pH-buffering capacity. The average hydroperiod had decreased by 4 months since 1998–99 in the pond where the extensive egg mortality had occurred. The total alkalinity, and the Mg2 + concentration had also significantly declined in the shallow water-table since 1998–99, from an average of 8.56 to 0.32 meq l− 1, and of 3.57 to 1.15 meq l− 1, respectively. This decline of the shallow groundwater buffering capacity could turn this pond more susceptible to the inorganic acidity associated with pyrite oxidation as the sediment S content was often above 0.03%. The initial ratio of S/Ca + Mg in the summer dry sediment was a good predictor of pore-water pH on re-wetting after desiccation (r2 = 0.802, p < 0.01). Therefore, this ratio can give some anticipation to mitigate the impact of acidity on toad hatching before these temporary ponds are reflooded on the next wet season. Our results suggest that the long-term damage to pond water levels can trigger a potential risk of soil acidification in the presence of iron-sulphide minerals., This research was partly funded by several sources: Radboud University Nijmegen (The Netherlands), the Spanish Ministry of Science and Innovation, the European Union Social Fund (CGL2006-04458/BOS), the fellowship grants CSIC-I3P to M.F. and AP-2001-3475 to C.G.-R., and the Junta de Andalucía (Excellence Research Project 932 and PAI Group RNM 128). The current MF's grant is supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq (401045/2014-5), program Ciência sem Fronteiras.

Temporary ponds are unpredictable habitats that exhibit inundation periods of variable duration (hydroperiods). We hypothesised that changes in microcrustacean assemblages, namely among ponds (spatial variation) and within ponds at a monthly scale (intra-annual variation), would differ according to hydroperiod length. We found that the microcrustacean assemblages of the study ponds demonstrated distinctive individual patterns that were dependent on monthly variation. During pond filling, species turnover was particularly high in short-hydroperiod ponds, probably due to the fast hatching of the initial pool of species, which seemed to determine subsequent species succession. Some of the long-hydroperiod ponds were able to hold water during the summer, which meant that they could harbour adult microcrustaceans in the early autumn, in contrast to the recently filled ponds; species turnover could thus increase at the onset of the inundation cycle. In the summer, species turnover decreased (while the contribution of nestedness to β-diversity increased) because only a few tolerant species were able to withstand the poor water quality found in drying ponds. We suggest that preserving the broader hydroperiod gradient, by protecting ponds with different environmental conditions within each hydroperiod category, would safeguard the ecological dynamics of the microcrustacean assemblages found in temporary ponds

The aim of this study was to assess aquatic plant distribution patterns in a Mediterranean temporary pond network (Doñana National Park, SW Spain). We analyzed differences in species composition employing multivariate ordination techniques; we specifically examined the importance of hydroperiod and physical and chemical variables in the five geomorphological areas across which the pond network is spread. The ponds significantly segregated along a north–south gradient, matching the segregation pattern of the aquatic plant assemblages. Ponds in the three northernmost areas showed higher levels of species richness than ponds in the two southernmost areas. In the north, ponds were present at higher densities, spanned a broader hydroperiod range, and had lower conductivity levels; these features were associated with the presence of wet-meadow species and larger numbers of submerged and emergent species. In the south, alkaline waters were mainly associated with different charophyte species, and the predominance of long-hydroperiod ponds helped in increasing the number of floating species. Managed ponds, which had been artificially deepened, contributed to increase pond heterogeneity and hydroperiod breadth across the entire network. At present, such ponds are key to the preservation of Doñana’s rich and unique aquatic plant community.

Southern Spain’s semi-arid habitats are a Mediterranean ecosystem modelled mainly by historic factors which make them unique in comparison with North African deserts. Southern Spanish vertebrates have adapted to the recent emergence of semi-arid habitats in varying degrees of success. This paper reviews the current status of these terrestrial vertebrates (amphibians, reptiles, birds and mammals), their origins and their main features in relation to this biogeographic area. The vertebrate fauna of the semi-arid southeast of the Iberian peninsula differs widely from the one in the semi-arid Maghreb mainly because the former is composed by generalist vertebrates and much less so by species adapted to arid conditions. Moreover, a large fraction of the vertebrates in the semi-arid Iberia does not exploit the semi- arid areas but depends on riparian and human-managed habitats. The species diversity is rather low since only a small fraction of Palaearctic, European or Mediterranean species can adapt to the ecological limitations imposed by aridity and dwell in these semi-arid habitats. Such adaptations comprehend features like trophic plasticity, low morphological specialization, high dispersal ability, shortened life cycles and behavioural mechanisms to exploit the limited resources available. This paper identifies major conservation issues and proposes specific courses of action.

Aim The imperfect detection of species may lead to erroneous conclusions about species–environment relationships. Accuracy in species detection usually requires temporal replication at sampling sites, a time-consuming and costly monitoring scheme. Here, we applied a lower-cost alternative based on a double-sampling approach to incorporate the reliability of species detection into regression-based species distribution modelling. Location Donana National Park (south-western Spain). Methods Using species-specific monthly detection probabilities, we estimated the detection reliability as the probability of having detected the species given the species-specific survey time. Such reliability estimates were used to account explicitly for data uncertainty by weighting each absence. We illustrated how this novel framework can be used to evaluate four competing hypotheses as to what constitutes primary environmental control of amphibian distribution: breeding habitat, aestivating habitat, spatial distribution of surrounding habitats and/or major ecosystems zonation. The study was conducted on six pond-breeding amphibian species during a 4-year period. Results Non-detections should not be considered equivalent to real absences, as their reliability varied considerably. The occurrence of Hyla meridionalis and Triturus pygmaeus was related to a particular major ecosystem of the study area, where suitable habitat for these species seemed to be widely available. Characteristics of the breeding habitat (area and hydroperiod) were of high importance for the occurrence of Pelobates cultripes and Pleurodeles waltl. Terrestrial characteristics were the most important predictors of the occurrence of Discoglossus galganoi and Lissotriton boscai, along with spatial distribution of breeding habitats for the last species. Main conclusions We did not find a single best supported hypothesis valid for all species, which stresses the importance of multiscale and multifactor approaches. More importantly, this study shows that estimating the reliability of non-detection records, an exercise that had been previously seen as a naive goal in species distribution modelling, is feasible and could be promoted in future studies, at least in comparable systems.

Recent and increasing interest in tempo- rary ponds as biodiversity reservoirs fosters our need to test sampling techniques for characterising their biological communities. We compared the efficiency of dip-netting to that of fyke nets in sampling the macroinvertebrate assemblage of a temporary pond in Don˜ ana National Park (SW Spain). We sampled the pond at four different times—morning, afternoon, evening and night—distinguishing between deep and shallow zones. In our sampling, dip-netting captured a higher number of taxa, and higher abundances of individuals than fyke nets. However, both techniques captured exclusive taxa, not recorded with the other device. Fyke nets distinguished between nocturnal and diurnal macroinvertebrates, and hence are more appropriate to study macroinvertebrate diel activity. We detected nocturnal activity in Gerris thoracicus larvae, and adults of Colymbetes fuscus, Rhantus suturalis, Rhantus hispanicus and Hydrochara flav- ipes. Conversely, larvae of Sympetrum fonscolombei and Notonecta spp., and adults of Notonecta glauca were mainly diurnal. The overall diel activity pattern of the macroinvertebrate assemblage depended on the diel activities of their integrating taxa and stages. Although dip-netting was more appropriate to sample macroinvertebrate assemblages in different micro- habitats, fyke nets better captured nocturnal and fast- swimming invertebrates. Consequently, the joint use of both sampling techniques would capture a better picture of the representative macrofauna of a tempo- rary pond than either one on its own

Invasive species cause deep impacts on ecosystems worldwide, contributing to the decline and extinction of indigenous species. Effective defences against native biological threats in indigenous species, whether structural or inducible, often seem inoperative against invasive species. Here, we show that tadpoles of the Iberian green frog detect chemical cues from indigenous predators (dragonfly nymphs) and respond by reducing their activity and developing an efficient defensive morphology against them (increased tail depth and pigmentation). Those defensive responses, however, were not activated against a highly dama- ging invasive predator (red swamp crayfish). Induced defences increased tadpole survival when faced against either indigenous dragonflies or invasive crayfish, so its inactivation in the presence of the invasive predator seems to be due to failure in cue recognition. Furthermore, we tested for local adaptation to the invasive predator by comparing individuals from ponds either exposed to or free from crayfish. In both cases, tadpoles failed to express inducible defences against crayfish, indicating that ca 30 years of contact with the invasive species (roughly 10 – 15 frog generations) have been insufficient for the evolution of recognition of invasive predator cues.

1. Diversity assessments and conservation management should take into account the dynamic nature of populations and communities, particularly when they are subject to highly variable and unpredictable environmental conditions. 2. This study evaluates the inter-annual variability in the assemblage composition (temporal turnover) of an amphibian community breeding in a highly dynamic habitat, a Mediterranean temporary pond system, during a 4-year period. 3. A comprehensive framework is provided to evaluate temporal turnover from data of a differing nature (species richness, presence/absence and relative abundance) and, especially, to discern variation in richness (species loss) from changes in the identity or abundance of species (species replacement). 4. Results show that the pond amphibian assemblages in Donana National Park exhibited high inter-annual variability during the study period, both in the number of species, species identity and their relative abundance. This result provides evidence for the inadequacy of surveys conducted only in one breeding season to characterize the species assemblage associated with a given pond. Besides, it suggests that a given pond offers different breeding opportunities over time, being suitable for different species depending on the year. This alternation will contribute to the medium-term preservation of all species in the assemblage. 5. It is highly relevant to preserve the natural dynamism and spatial variability of temporary pond systems, which will favour the conservation of populations through their intrinsic variability

Based on field data simultaneous with Landsat overpasses from six different dates, we developed a robust linear model to predict subpixel fractions of water cover. The model was applied to a time series of 174 Landsat TM and ETM+ images to reconstruct the flooding regime of a system of small temporary ponds and to study their spatio-temporal changes in a 23-year period. We tried to differentiate natural fluctuations from trends in hydrologic variables (i.e., hydroperiod shortening) that may threaten the preservation of the system. Although medium-resolution remote sensing data have rarely been applied to the monitoring of small-sized wetlands, this study evidences its utility to understand the hydrology of temporary ponds at a local scale. We show that the temporary ponds in Doñana National Park constitute a large and heterogeneous system with high intra and inter-annual variability. We also evidence that the conservation value of this ecosystem is threatened by the observed tendency to shorter annual hydroperiods in recent years, probably due to aquifer exploitation. This system of temporary ponds deserves special attention for the high density and heterogeneity of natural ponds, not common in Europe. For this reason, management decisions to avoid its destruction or degradation are critical.

1. The main reproductive parameters of exotic Trachemys scripta elegans in established populations from two ponds in southern Spain are described. 2. Females were found to reproduce at 5 years of age, although sexually mature individuals of 4 and 3 years of age were also detected. Annual reproductive frequency was estimated to be 80-86% of reproductive females. Mean clutch size was 11.5 eggs and was not correlated with maternal body size. 3. The number of follicles of different size in ovaries suggested that four or more clutches could be laid per season. Eggs were laid from April to June (inclusive) mainly during morning hours, when females were easily detected during nesting trips. 79.5% of eggs were fertile. 4. Reproductive parameters of this species in southern Spain were of similar or even higher values than in native areas, thus placing them among chelonian species of earlier maturity. 5. Although chelonians might never be considered explosive breeders, the number of T. s. elegans individuals could surpass that of native aquatic chelonians in southern Spain, where T. s. elegans reach maturity earlier, are more fecund and their eggs are more fertile. Copyright © 2008 John Wiley & Sons, Ltd.

Reference intervals of hematologic and biochemical blood profiles were obtained from 56 male and 58 female Mediterranean pond turtles (Mauremys leprosa) captured from the wild in different periods of their annual cycle. Mean (or median in nonnormal distributions) values of leukocyte differential were 53.8% and 58.5% heterophils, 35.3% and 32.6% eosinophils, 6.3% and 5.8% lymphocytes, 4.3% and 2% monocytes, and 0% and 0% basophils in males and females, respectively. Biochemical values did not differ from other chelonians, but values were generally higher in females than in males.

This work presents the concentrations of twenty PCB congeners, p,p0 -DDT, and its two main metabolites, p,p0 -DDE, p,p0 -TDE, As, Cd, Cu, Pb, and Zn found in common chameleon eggs from nine different nests located in Southwest Spain. Of the heavy metals and arsenic, Zn and Cu exhibited the highest concentrations in egg contents (ranging from 10 100 to 12 950 and from 567 to 706 ng g—1 wet weight basis [w.w.], respectively) and eggshells (ranging from 5605 to 13 290 ng g—1 w.w. for Zn and from 1487 to 4361 ng g—1 w.w. for Cu). Total PCB concentrations in egg contents ranged from 32 to 52 ng g—1 w.w. and were higher than total dichlorodiphenylethanes concentrations (ranging from 0.67 to 1.9 ng g—1 w.w., calculated as the sum of p,p0 -DDT plus p,p0 -DDE and p,p0 -TDE). Comparison of the data from the present study with the data from a study conducted in 1997 revealed a large decrease in Pb concentration and a twofold increase in PCB concentrations. Taking into account all the pollutants investigated, the contamination level found in common chameleon eggs from Southwest Spain was generally lower than has been reported in the literature for eggs of different reptile species. However, it should be borne in mind that most of the data found in the literature refer to highly polluted areas

In Doñana National Park, most aquatic habitats are temporary. Ponds dry up during the summer, and are filled again when phreatic levels rise after heavy rains. Permanent and semipermanent ponds, and a chain of long-hydroperiod ponds are formed in an area of the park where discharges of the dune and regional aquifers coincide. Over the last few decades, groundwater abstractions have severely affected the park. Using Landsat images (1975-2014), we estimated the variation in the inundated areas of the park’s largest ponds. All ponds have increased their dependency on annual rainfall in recent decades. Two seasonal ponds located close to urban pumping stations are currently dry. We found that other seasonal ponds have tended to have shorter hydroperiod and have dried up in the summer in recent years, including in very rainy years. The largest permanent pond had not such wide interannual fluctuations in its inundated area in the 1970s as those experienced recently. During the last decades, its inundated area is strongly correlated with annual rainfall, and the pond is close to desiccation in years of low rainfall. These results show that this pond network is severely threatened by desiccation. It is urgent to control groundwater extraction in the area to preserve the integrity of this important wetland, En Doñana, la mayoría de los hábitats acuáticos son temporales. Las lagunas se desecan en verano y vuelven a inundarse con la elevación del nivel freático que se produce tras las abundantes lluvias otoñales o invernales. En la zona central del parque se localizan las lagunas permanentes y semipermanentes, que junto con otras de largo hidroperiodo forman una cadena de lagunas donde coinciden las descargas del acuífero dunar y el gran acuífero regional. En las últimas décadas, se han realizado extracciones de agua del acuífero que han afectado seriamente al parque. En este estudio, usando imágenes del satélite Landsat (1975-2014), hemos estimado la variación de la superficie inundada de las mayores lagunas del parque. En todas se observa un incremento en las últimas décadas de su dependencia de las lluvias anuales. Dos lagunas estacionales, situadas en las proximidades de estaciones de bombeo de aguas se consideran actualmente secas. En algunas lagunas, se observa una tendencia a acortar su periodo de inundación, secándose en los veranos de los años más recientes, incluso en años lluviosos. La laguna más permanente no sufría tan amplias variaciones en la superficie que mantenía inundada en verano en los años 70, como las que observan en la actualidad, cuando su inundación en verano está estrechamente correlacionada con las lluvias anuales, llegando en los últimos veranos a niveles muy próximos a la desecación. Estos resultados indican que la red de lagunas está severamente amenazada de desecación. Para preservar la integridad de este importante humedal, es urgente controlar las extracciones de agua del acuífero

Temporary ponds are highly variable systems where resource availability and community structure change extensively over time, and consequently the food web is highly dynamic. Amphibians play a critical role both as consumers and prey in aquatic communities and yet there is still little information on the trophic status of most amphibians. More importantly, little is known about the extent to which they can alter their trophic ecology in response to changing conditions.We experimentally investigated the effects of increased amphibian density, presence of intraguild competitors, and presence of native and invasive predators (either free or caged) on the trophic status of a Mediterranean amphibian guild, using stable isotopes. We observed variations in δ13C and δ15N isotopic values among amphibian species and treatments and differences in their food sources. Macrophytes were the most important food resource for spadefoot toad tadpoles (Pelobates cultripes) and relatively important for all anurans within the guild. High density and presence of P. cultripes tadpoles markedly reduced macrophyte biomass, forcing tadpoles to increase their feeding on detritus, algae and zooplankton, resulting in lower δ13C values. Native dytiscid predators only changed the isotopic signature of newts whereas invasive red swamp crayfish had an enormous impact on environmental conditions and greatly affected the isotopic values of amphibians. Crayfish forced tadpoles to increase detritus ingestion or other resources depleted in δ13C. We found that the opportunistic amphibian feeding was greatly conditioned by intra- and interspecific competition whereas non-consumptive predator effects were negligible. Determining the trophic plasticity of amphibians can help us understand natural and anthropogenic changes in aquatic ecosystems and assess amphibians’ ability to adjust to different environmental conditions.

The presence of the exotic weevil Stenopelmus rufinasus (Coleoptera: Curculionidae) is closely related to the occurrence of the exotic red water fern, Azolla filiculoides. In this paper, we present the first records of S. rufinasus in Doñana National Park (SW Spain), based on sampling of macroinvertebrates in 91 temporary ponds, including monthly samples of 22 ponds, during two successive years (2005-2007). The exotic weevil was present in 21% of the sampled ponds where the host plant, A. filiculiodes, was not detectable. Because A. filiculoides can reach high densities in an adjacent area of marsh, we suggest that the occurrence of the exotic weevil in these ponds is a consequence of dispersal from nearby marshes. Our study demonstrates that S. rufinasus adults can occur at relatively high densities in ponds where the host plant is not present, suggesting that such apparently “host-free” sites may act as stepping stones for the spread of this species, La presencia de la especie de gorgojo exótico Stenopelmus rufinasus (Coleoptera: Curculionidae) está íntimamente rela- cionada con la planta acuática exótica Azolla filiculoides. En este estudio se registró por primera vez la presencia de S. rufinasus en el Parque Nacional de Doñana (SO España) tras realizar un muestreo de macroinvertebrados en 91 lagunas que incluye muestreos mensuales de 22 de las mismas durante dos años consecutivos (2005-2007). El gorgojo exótico estuvo presente en el 21% de las lagunas muestreadas a pesar de que su supuesto hospedador, A. filiculiodes, no fue detectado. Dado que A. filiculiodes puede alcanzar grandes densidades en la marisma adyacente, sugerimos que la presencia del gor- gojo exótico en las lagunas temporales se debe a su dispersión desde la marisma. Este estudio demuestra que individuos adultos de S. rufinasus pueden aparecer con densidades relativamente altas en lagunas donde su hospedador potencial no está presente, lo que sugiere que estos sitios libres de hospedador podrían actuar como zonas de paso para la dispersión de la especie

Macroinvertebrate assemblages of temporary ponds are ideal model systems to explore biodiversity patterns and metacommunity ecology. In addition, the study of the environmental variables driving such biodiversity patterns is essential in establishing proper guidelines for the conservation of the singular fauna of temporary ponds, especially since such ponds are vulnerable systems. We analysed the macroinvertebrate assemblages and environmental characteristics of 80 ponds spread across the Doñana National Park, SW Spain to (i) analyse macroinvertebrate β-diversity and metacommunity structure; and (ii) discern the main environmental and spatial drivers of these patterns. The pond network was highly heterogeneous as temporary ponds were highly variable. Macroinvertebrate β-diversity partitioning showed that species replacement made the greatest contribution to total β-diversity while the contribution of nestedness was small. The macroinvertebrate community structure and β-diversity were similarly driven by: electrical conductivity (and co-variables alkalinity, pH, and ion concentrations), plant richness (and the co-variable pond surface area), maximum depth, marsh, and coastal proximity as well as two spatial descriptors extracted from Moran's eigenvector maps. The spatial descriptors indicated that large interpond distances were involved, suggesting that species dispersal limitations only take place over long distances in the area. Those taxa that departed from the general nested pattern, termed idiosyncratic, significantly contributed to the maintenance of high pond network diversity through the species replacement and occurred within particular environmental conditions in the pond network. These results reveal that environmental heterogeneity and connectivity are key factors in the preservation of high macroinvertebrate diversity in nested pond networks with high numbers of idiosyncratic species.

Invasive crayfish have severely impacted invaded aquatic ecosystems worldwide. We studied temporal and spatial variation in the range expansion of the red swamp crayfish at one of the first European localities to which it was introduced: Doñana National Park (SW Spain). In contrast to the rapid range expansion witnessed in other areas, this invasive crayfish has not spread across the entire park. Instead, its distribution has expanded during wet periods, but contracted during drought periods. The red swamp crayfish has caused steep amphibian declines in other invaded areas. However, after approximately 35 years of crayfish presence in Doñana National Park, we have yet to detect a reduction in the number or occurrence of amphibian species. Amphibians may thus be protected by the large abundance of temporary ponds in the area, which provides them with an effective refuge network. We show that natural fluctuations in annual rainfall and in the number of ponds filled can temporarily eliminate invasive crayfish from particular areas. This fact should be taken into account when attempting to reduce the impact of crayfish on aquatic communities, intensifying crayfish removal during particularly dry years, when it is most effective.

Activity, mobility, growth rates, and space use of 48 hatchling spur-thighed tortoises. Testudo graeca, were monitored over a period of 8 months, from emergence from the nest in September until May. Individuals were followed by means of thread trailing and radio tracking. Overall average distance moved was 4.42 m/day and average home-range size was 13.7 m2. Hatchlings were active from emergence until mid-December, exhibited discontinuous hibernation until mid-February, and reached highest activity and mobility values in April-May. Overall. mobility varied significantly with daily solar radiation values and maximum temperature, and was significantly dependent on body condition in winter. Body size and mass had no influence on individual performance, and a significant proportion of variance among individuals remained unexplained. Little growth occurred in autumn and body condition decreased steadily, increasing only from February onwards. Growth rates increased in March-April. No individual differences in growth rates were detected, initial body size being the main determinant of body size after 8 months.

Seasonal variation in macroinvertebrate assemblages usually is attributed to environmental variability, but this relationship is unclear in temporary ponds because they are highly dynamic across time. We assessed the influence of environmental variables and biotic interactions on macroinvertebrate community structure in 22 temporary ponds sampled monthly over 2 successive years that differed in rainfall. We hypothesized that abiotic and biotic variables would have different influences on macroinvertebrates having different dispersal abilities (capable of dispersal or not) and dietary modes (predaceous or not). Constrained Analysis of Principal Coordinates showed mainly seasonal influences on community assembly. During the filling phase, water-column total P (TP) and pH were important, whereas maximum depth, pH, electrical conductivity, and dissolved O2 were important during the aquatic phase. When ponds were close to desiccation, water-column electrical conductivity and TP and sediment organic matter were most influential. Predation by urodele adults occurred early in the inundation cycle and by urodele larvae when the ponds were close to desiccation. Negative species checkerboards (patterns of species noncoexistence) revealed that primarily competitive exclusion was in operation immediately after pond inundation, whereas competitive exclusion and habitat segregation were operating in tandem during the subsequent months. During the drying phase, general deterioration of environmental conditions and high pressure exerted by biotic interactions may trigger macroinvertebrate strategies to survive desiccation. Variability in pond characteristics allows macroinvertebrate species to assemble and disassemble in response to pond inundation–desiccation cycles and, thus, supports high biodiversity in the area

Amphibian larvae constitute a large fraction of the biomass of wetlands and play important roles in their energy flux and nutrient cycling. Interactions with predators and competitors affect their abundance but also their foraging behaviour, potentially leading to non-consumptive cascading effects on the whole trophic web. We experimentally tested for plastic changes in larval trophic ecology of two anuran species in response to competitors and the non-lethal presence of native and non-native predators, using stable isotope analysis. We hypothesized that tadpoles would alter their diet in the presence of competitors and native predators, and to a lesser extent or not at all in the presence of non-native predators. First, we conducted a controlled diet experiment to estimate tadpole turnover rates and discrimination factors using Pelobates cultripes and Bufo calamita. Turnover rates yielded a half-life of 15–20 days (attaining a quasi-isotopic equilibrium after 2 months), whereas discrimination factors for natural controlled diets resulted in different isotopic values essential for calibration. Second, we did an experiment with P. cultripes and Rana perezi (=Pelophylax perezi) where we manipulated the presence/absence of predators and heterospecific tadpoles using microcosms in the laboratory. We detected a significant shift in trophic status of both amphibian species in the presence of non-native crayfish: the d15N values and macrophyte consumption of tadpoles increased, whereas their detritus consumption decreased. This suggests that tadpoles could have perceived crayfish as a predatory risk or that crayfish acted as competitors for algae and zooplankton. No dietary changes were observed in the presence of native dragonflies or when both tadpole species co-occurred. Stable isotopic analysis is an efficient way to assess variation in tadpoles’ tropic status and hence understand their role in freshwater ecosystems. Here we provide baseline isotopic information for future trophic studies and show evidence for plastic changes in tadpoles’ use of food resources under different ecological cenarios.

The body size of specimens of Trituras marmoratus pygmaeus from Doñana is the smallest recorded for this subspecies. Snout-vent length averages 42.3mm in males, and 43.9mm in females. Mean body mass in males is 2.04 g and 2.29g in females. The age of newts was estimated by means of skeletochronological methods. The maximum longevity recorded was 10 years in females and nine years in males, with one or two years being the age at maturity. As in other newts, body size is not a good predictor of age, since a wide range of body length was found within each age class. Growth in females was substantial in subsequent years, showing an overall positive tendency. However, males showed slight or even negative growth. Newts from Doñana are different from other nearby localities with similar climatic characteristics. This is mainly due to their short juvenile and terrestrial phase.

Amphibian chytridiomycosis, caused by infection with the non-hyphal, zoosporic chytrid fungus Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease recognised as a cause of recent amphibian population declines and extinctions worldwide. The Doñana National Park (DNP) is located in southwestern Spain, a country with widespread Bd infection. This protected area has a great diversity of aquatic habitats that constitute important breeding habitats for 11 native amphibian species. We sampled 625 amphibians in December 2007 and February to March 2008, months that correspond to the early and intermediate breeding seasons for amphibians, respectively. We found 7 of 9 sampled species to be infected with Bd and found differences in prevalence between sampling periods. Although some amphibians tested had higher intensities of infection than others, all animals sampled were apparently healthy and, so far, there has been no evidence of either unusually high rates of mortality or amphibian population declines in the DNP. © Inter-Research 2012.

Pancreatitis associated with the helminth Serpinema microcephalus was found in three of 19 free-ranging red-eared slider turtles (Trachemys scripta elegans) captured between March 2003 and September 2004 in southern Spain. Microscopic changes were associated with parasite migrations and were characterized by central areas of necrosis surrounded by leukocytes and resulted in destruction of exocrine tissue. The blood profile of one of the three female turtles revealed eosinophilia and hyperglycemia, common in helminth infections and pancreatic disorders respectively. These are the first reported cases of pancreatitis caused by the nematode S. microcephalus in the exotic and newly colonized host T. s. elegans.