Abstract Despite increasing research on warming and biodiversity, knowledge on how temperature shapes community size structure remains limited, which is one of the main challenges in assessing the consequences of climate change. This gap is evident in vulnerable ecosystems like ponds, crucial for aquatic biodiversity but highly sensitive to temperature increases due to their small size. This study assessed the main climatic and local drivers influencing zooplankton community size structure in 141 ponds across four European countries and Uruguay, covering a wide latitudinal and trophic gradient with standardized sampling. Using linear mixed models, results revealed that local factors, such as trophic status and morphometric pond characteristics, were more consistently associated with size‐spectrum parameters than climatic variables. The normalized size spectrum slopes (ordinary least square regression, OLS) became steeper with higher chlorophyll a (Chl a ) concentrations, reflecting dominance of small zooplankton, suggesting reduced energy transfer efficiency to higher trophic levels, and possibly weaker top‐down phytoplankton control. Conversely, ponds with lower Chl a showed flatter slopes, indicating more large zooplankton and possibly greater top‐down control. The overall intercept was higher in deeper ponds with abundant aquatic vegetation, suggesting greater overall abundance across size classes. Size spectrum metrics did not vary significantly along climatic gradients. These results suggest that zooplankton community size structure in ponds appears to be more closely related to local environmental conditions than large‐scale climatic gradients. This highlights the key role of local habitat characteristics in shaping zooplankton size structure and energy transfer dynamics.

Mediterranean temporary ponds are ecologically vital ecosystems that support numerous endemic and rare species. These shallow ponds undergo unpredictable inter-annual fluctuations, with flooding and dry phase cycles driven largely by meteorological conditions. This study investigates how changes in the physical and chemical environment, resource availability (bottom-up), and predation (top-down) throughout the hydroperiod influence the structure and dynamics of planktonic communities. We analyzed the size spectrum (i.e., the relationship between individual body size and abundance) including phytoplankton and zooplankton communities in three freshwater temporary ponds in NE Spain, sampled monthly over four consecutive hydrologic cycles (2016–2020). Hydroperiod ranged from 2 to 8 months, allowing us to assess whether hydroperiod duration modulates the relative influence of environmental, bottom-up, and top-down controls. Results indicate that macroinvertebrate predation was the main driver of a declining size spectrum intercept, suggesting a general reduction in abundance across all planktonic size classes. Longer hydroperiods intensified top-down effects, also steepening the slope of the spectrum. In contrast, environmental fluctuations across the hydroperiod did not significantly influence the size spectrum shape, regardless of hydroperiod length. These findings highlight size spectra as useful indicators of the temporal changes in the trophic structure and biomass transfer in ephemeral aquatic systems.

Ponds are key habitats for regional freshwater biodiversity and play a fundamental role in enhancing connectivity between aquatic ecosystems. Despite their importance, ponds are one of the most neglected water ecosystems due to their small size and are particularly affected by climate change and anthropogenic activities. Zooplankton communities serve as sensitive indicators of environmental stressors, such as changes in trophic state, hydroperiod variability, and habitat degradation. Therefore, understanding the drivers of biodiversity and the size structure of the zooplankton community in Mediterranean ponds is important, as it provides valuable insights into how different stressors may impact this community and ecosystems, and provides valuable insights for making appropriate decisions for its conservation. Here, we evaluated the taxonomic and size structure of the zooplankton community and its relationship with trophic status, the presence of fish, macrophyte abundance, morphometry, hydroperiod variability, and land use by conducting a comprehensive ecological characterisation of 30 Mediterranean freshwater ponds. Our results suggest that size metrics are affected by factors related to the trophic status of ponds. Eutrophic ponds, with the highest chlorophyll-a concentration, oxygen supersaturation, presence of fish, and low habitat complexity (i.e., fewer macrophytes), were dominated by small-size zooplankton, and the community was less size diverse (i.e., steeper slope of the size spectra and lower size diversity values). Also, ponds with a high habitat complexity and lower surface area had higher zooplankton biomass (i.e., higher intercept of the size spectra). In contrast, zooplankton richness was only positively influenced by pond surface area. Our results showed that size metrics reflected changes in the zooplankton community along the trophic status and biotic gradients, whereas the taxonomic metrics were more related to the morphometry of ponds. Size-related variables can be effective tools to evaluate the drivers of change of pond communities in the Mediterranean region and possibly others, particularly when taxonomic metrics do not show a significant response. From a management perspective, the results demonstrate the potential of size-based metrics for assessing the ecological status of Mediterranean ponds.

Despite being widely applied, the implementation of problem-based/project-based learning (PBL) activities still poses several challenges. Activity design and evaluation and monitoring processes stand out as the most complex aspects of the methodology. This study provides support for teachers to improve PBL assessment and monitoring systems in the scientific and technical field. To do this, the evaluation and monitoring tools used in the most representative PBL activities at different levels of higher education were collected. These were then integrated to generate new, more complete tools (three rubrics and two evaluation scales). These tools were then appli0ed to PBL activities, and the teachers involved (n=11) assessed their view of their functioning. The results indicate that the participating teachers perceived that the tools generated in this way functioned better than the ones used originally, highlighting their completeness, adaptability and ease of use. The study suggests that support in the design of tools could lead to improvements in the process of monitoring and evaluating PBL activities by making them more agile, objective, systematic and efficient.

Mediterranean Temporary ponds (MTPs) are suffering severe alterations in their hydrological and salinity regime through global change, and restoration or conservation of these habitats is a priority. However, there is little information that can be used as a scientific basis for restoration.We studied the taxonomic and functional diversity of zooplankton communities in a set of 96 ponds in Doñana, Spain during four consecutive hydroperiods after their creation. We examined the differences across hydroperiods in alpha and beta diversity (and its turnover and nestedness components) of the rotifer, cladoceran and copepod community, as well as the influence of local environmental variables including the proximity to natural wetlands.There was no general increase in diversity indices after the first two hydroperiods. We found that shorter hydroperiods significantly reduced taxonomic diversity, but increased the contribution to functional beta diversity through turnover. Shorter hydroperiods also reduced community complexity, with long-term effects. Conductivity was the most important predictor of zooplankton alpha and beta diversity, but the direction of its effects changed between hydroperiods. The distance from a natural source of colonists, and pond depth, were key during the early stage of community assembly and after a hydrological perturbation.Our results suggest that new restoration projects for MTPs should focus on increasing local environmental heterogeneity and on reducing vulnerability to salinization.The use of functional approaches in monitoring studies can improve our understanding of mechanisms and processes affecting zooplankton community assembly under dynamic hydrological regimes. This in turn can help us predict the consequences of management and restoration policies for biodiversity conservation in MTPs.

Tot i la seva àmplia aplicació, la realització de les activitats d’aprenentatge basat en projectes i en problemes (ABP) encara suposa diversos reptes. El disseny de l’activitat i els processos d’avaluació i de seguiment que comporta destaquen entre els aspectes més complexos de la metodologia. Aquest treball aporta una experiència de suport al professorat per millorar els sistemes d’avaluació i de seguiment de l’ABP en l’àmbit cientificotècnic. Per fer-ho es varen recollir les eines d’avaluació i de seguiment utilitzades a les activitats d’ABP més representatives dels diferents graus de la facultat. Les eines recollides es van integrar entre elles generant eines noves més completes (tres rúbriques i dues escales de valoració). Aquestes eines es van aplicar a activitats d’ABP, i el professorat responsable (n = 11) va valorar la seva percepció sobre la manera com funcionaven. Els resultats obtinguts indiquen que el professorat participant va percebre un millor funcionament de les eines generades comparades amb les utilitzades originàriament, destacant- ne la compleció, l’adaptabilitat i l’agilitat d’ús. L’estudi suggereix que el suport en el disseny d’eines podria revertir en la millora del procés de seguiment i avaluació de les activitats d’ABP fent-lo més àgil, objectiu, sistemàtic i eficient.

The spatial distribution of the pondscapes in Europe were obtained from global and local databases and presented in deliverable D3.2 (report on spatial distribution of pondscapes in Europe). However, the information was too coarse and necessary features of the ponds could not be retrieved from the available local databases. Therefore, available datasets from each participant country were collected and a common database was created. This database consists of spatial information such as latitude and longitude of the ponds in geographic coordinates, name, code, land cover, intensity, hydro period, surface area, perimeter, maximum depth, mean depth, altitude, measurement year, created year, information about work packages and installed sensor information. Geocoded and detailed GIS layers showing all ponds were created and it will be used as ground truth for mapping and validating hydro period information. A web application has been developed to display spatial distribution and available information of ponds from the individual countries. The application allows users to dynamically visualize the ponds and download pond’s available data, hydro period information and pond database spatially: https://ponderful.hidrosaf.com/.

Aphanius iberus is an endemic cyprinodontoid fish species of Mediterranean ponds in danger of extinction. In this study, we studied some abiotic and biotic factors that can influence A. iberus’s size structure and density in Mediterranean brackish ponds. We sampled fish using fyke nets in 10 ponds of Empordà (Spain) during the spring season. Our results showed that a better ecological status (according to the Water Quality of Lentic and Shallow Ecosystems (QAELS) index), pond’s depth and pond’s isolation (reflected by an increase in total nitrogen) were related to larger individual sizes and more size-diverse populations. Increasing the salinity is known to help the euryhaline A. iberus acting as a refuge from competitors. Nevertheless, our results showed that higher conductivities had a negative effect on A. iberus’s size structure, leading to a decrease in the mean and maximum size of the fish. Fish abundance (expressed as captures per unit of effort (CPUE)) seemed to increase with increasing the pond’s depth and total nitrogen (the latter reflecting pond isolation). In conclusion, our results suggest that achieving a better pond ecological status may be important for the conservation of endangered A. iberus, because better size-structured populations (i.e., larger mean and average lengths) were found at higher water quality conditions.

In this study, performed in Mediterranean brackish ponds during spring season, we assessed the effects of biotic interactions and abiotic factors on the size and taxonomic structure of the phytoplankton and zooplankton. We used a taxonomic and a size diversity index as a descriptor of the community structure. We predicted that the size diversity of each trophic level would be mainly related to biotic interactions, such as size-based fish predation (in the case of zooplankton) and food resource availability (in the case of phytoplankton), whereas taxonomic diversity would be more affected by abiotic variables (e.g., conductivity, pond morphology). Our results showed a negative relationship between phytoplankton size diversity and food resource availability leading to low size diversities under food scarcity due to dominance of small species. Conductivity also negatively affected the phytoplankton size diversity, although slightly. Regarding zooplankton size diversity, none of predictors tested seemed to influence this index. Similar fish size diversities among ponds may prevent a significant effect of fish predation on size diversity of zooplankton. As expected, taxonomic diversity of phytoplankton and zooplankton was related to abiotic variables (specifically pond morphometry) rather than biotic interactions, which are usually body size dependent, especially in these species-poor brackish environments.

Understanding the colonisation process in zooplankton is crucial for successful restoration of aquatic ecosystems. Here, we analyzed the clonal and genetic structure of the cyclical parthenogenetic rotifer Brachionus plicatilis by following populations established in new temporary ponds during the first three hydroperiods. Rotifer populations established rapidly after first flooding, although colonisation was ongoing throughout the study. Multilocus genotypes from 7 microsatellite loci suggested that most populations (10 of 14) were founded by few clones. The exception was one of the four populations that persisted throughout the studied hydroperiods, where high genetic diversity in the first hydroperiod suggested colonisation from a historical egg bank, and no increase in allelic diversity was detected with time. In contrast, in another of these four populations, we observed a progressive increase of allelic diversity. This population became less differentiated from the other populations suggesting effective gene flow soon after its foundation. Allelic diversity and richness remained low in the remaining two, more isolated, populations, suggesting little gene flow. Our results highlight the complexity of colonisation dynamics, with evidence for persistent founder effects in some ponds, but not in others, and with early immigration both from external source populations, and from residual, historical diapausing egg banks.

Body size has been widely recognised as a key factor determining community structure in ecosystems. We analysed size diversity patterns of phytoplankton, zooplankton and fish assemblages in 13 data sets from freshwater and marine sites with the aim to assess whether there is a general trend in the effect of predation and resource competition on body size distribution across a wide range of aquatic ecosystems. We used size diversity as a measure of the shape of size distribution. Size diversity was computed based on the Shannon-Wiener diversity expression, adapted to a continuous variable, i.e. as body size. Our results show that greater predation pressure was associated with reduced size diversity of prey at all trophic levels. In contrast, competition effects depended on the trophic level considered. At upper trophic levels (zooplankton and fish), size distributions were more diverse when potential resource availability was low, suggesting that competitive interactions for resources promote diversification of aquatic communities by size. This pattern was not found for phytoplankton size distributions where size diversity mostly increased with low zooplankton grazing and increasing nutrient availability. Relationships we found were weak, indicating that predation and competition are not the only determinants of size distribution. Our results suggest that predation pressure leads to accumulation of organisms in the less predated sizes, while resource competition tends to favour a wider size distribution.

The magnitude of community-wide dispersal is central to metacommunity models, yet dispersal is notoriously difficult to quantify in passive and cryptic dispersers such as many freshwater invertebrates. By overcoming the problem of quantifying dispersal rates, colonization rates into new habitats can provide a useful estimate of the magnitude of effective dispersal. Here we study the influence of spatial and local processes on colonization rates into new ponds that indicate differential dispersal limitation of major zooplankton taxa, with important implications for metacommunity dynamics. We identify regional and local factors that affect zooplankton colonization rates and spatial patterns in a large-scale experimental system. Our study differs from others in the unique setup of the experimental pond area by which we were able to test spatial and environmental variables at a large spatial scale. We quantified colonization rates separately for the Copepoda, Cladocera and Rotifera from samples collected over a period of 21 months in 48 newly constructed temporary ponds of 0.18-2.95 ha distributed in a restored wetland area of 2,700 ha in Doñana National Park, Southern Spain. Species richness upon initial sampling of new ponds was about one third of that in reference ponds, although the rate of detection of new species from thereon were not significantly different, probably owing to high turnover in the dynamic, temporary reference ponds. Environmental heterogeneity had no detectable effect on colonization rates in new ponds. In contrast, connectivity, space (based on latitude and longitude) and surface area were key determinants of colonization rates for copepods and cladocerans. This suggests dispersal limitation in cladocerans and copepods, but not in rotifers, possibly due to differences in propagule size and abundance.

Over 30 years after drainage for agriculture, a 2700 ha temporary marshland was recently restored in Doñana National Park. We describe the recovery of zooplankton communities (copepods, cladocerans and rotifers) in 47 new temporary ponds excavated as part of the restoration project during the first two hydroperiods (April 2006 and 2007), and compare them to those of eight reference sites in the surrounding marshland. Major changes in the species composition and abundance occurred in new ponds between years. While rotifers and cyclopoid copepods dominated in terms of number of individuals in 2006, calanoid copepods and cladocerans were the most abundant groups in 2007. Rotifer species richness was significantly lower in 2007, but there was an increase in Simpson and β-diversity in 2007 owing largely to a dramatic decline in the abundance of Hexarthra cf. fennica (rare in reference sites) from 93% of all rotifer individuals in new ponds in 2006 to only 32% in 2007. In contrast, species richness of copepods and cladocerans was significantly higher in new ponds in 2007, but there were no changes in Simpson diversity. β-Diversity of cladocerans was also significantly higher in 2007. In 2006, the species richness of cladocera and copepods was significantly lower in new ponds than in reference sites, but by 2007 there were no differences in richness or Simpson diversity. Overall, 7 copepod, 13 cladoceran and 26 rotifer taxa were recorded in new ponds, including 80% of taxa recorded in reference sites. These results indicate that zooplankton communities can be rapidly restored in Mediterranean temporary wetlands, at least when large source populations in the surrounding area reduce dispersal limitation. They also illustrate the importance of comparing different metrics of richness and diversity in studies of zooplankton restoration.

Is Microtox R toxicity related to potentially harmful algae proliferation in Mediterranean salt marshes? Mediterranean salt marshes are ecosystems that are highly inuenced by sea changes and freshwater inputs from runoff. In these ecosystems, toxic and non-toxic algae blooms often produce large and unpredictable biomasses of phytoplankton. The Microtox R test has been described as a successful, quick method for detecting toxicity in various phytoplankton taxa. Our study sought to test the efciency of Microtox R in detecting toxic HAB in Mediterranean salt marshes. The results showed that the Microtox R test was able to detect toxic substances in the particulate matter of several lagoons in the Empord` a salt marshes. This Microtox R toxicity coincided with periods when potentially harmful cyanobacteria, dinoagellates and haptophytes had a high biomass. The results suggest that potentially harmful phytoplankton cannot be ruled out as a source of Microtox R toxicity or as a source of other organism kills and sub-acute effects in Mediterranean salt marshes.

We sought to identify environmental factors influencing crustacean zooplankton species richness in brackish lagoons and to elucidate whether crustacean zooplankton species richness and trophic structure of brackish lagoons differ among two regions with contrasting temperatures. We sampled 35 and 42 brackish lagoons (salinity ranging from 0.3 to 55‰) in Mediterranean Catalonia (NE Spain) and northern‐temperate Denmark, respectively. No significant differences were found in total crustacean zooplankton species richness or cladoceran richness between the climatic regions. Calanoid richness was higher in Denmark than in Catalonia, while cyclopoid richness was higher in Catalonia. Salinity was the most important variable associated with zooplankton species richness in both regions, richness of total zooplankton species, cladocerans and cyclopoids being negatively related with salinity. In both regions, a shift occurred from dominance of large filter feeding cladoceran species at low salinities to copepods and small cladoceran species at higher salinities. Cladoceran richness increased with increasing total phosphorus, but was not influenced by total nitrogen or chlorophyll‐a. Trophic structure in Mediterranean brackish lagoons showed a more pronounced seasonal variation than in north temperate brackish lagoons. Our results imply that the indirect effects of climate warming, such as changes in salinity and hydrology, will have a larger impact on brackish lagoon ecosystems than the increase in temperature per se.

Environmental factors accountable for bacterioplankton or phytoplankton biomass dominance were analysed in a confined Mediterranean salt marsh (Empordà Wetlands, NE Spain). Two basins located in the same salt marsh, and with differences in size and catchment's area were compared, during four characteristic situations of the hydroperiod. Since bacterio- or phytoplankton relationships may be affected by other factors such as diel variations or vertical differences in nutrient composition and distribution, high frequency fluctuations due to these factors were also taken into account. Differences in catchment area appeared to be the more plausible explanation of differences in nutrient and organic carbon accumulation among basins, since during confinement basins essentially accumulate the allochthonous nutrient and organic matter supplies that previously entered by runoff. DOC (Dissolved Organic Carbon) favoured the bacterioplankton biomass increase, but also was the main variable significantly affecting phytoplankton biomass. Basins showed marked differences in bacterio- and phytoplankton dominances. Relationships between phytoplankton and bacterioplankton were positive, negative or not significant, depending on the basin and on the period of the year. The phytoplankton mixotrophic capabilities, both phagotrophy and osmotrophy, and their production of UV-screening compounds, as sunscreen, may explain the significant correlation between DOC and phytoplankton biomass, and the significant effect of phytoplankton on bacterioplankton found in these ecosystems.

1. The Ter Vell (NE Iberian Peninsula) is a eutrophic coastal lagoon that has been mostly flooded by excessive irrigation water during recent decades. During 2001 and 2002 the lagoon was subject to several water management actions, the main consequence of which was a change in the hydrological regime due to drastically reduced irrigation water inputs to the lagoon.2. In order to comply with the Water Framework Directive, all the management actions in an ecosystem should be focused on protecting and, where necessary, improving its ecological status.3. The aims of this study were (1) to analyse whether the hydrological change caused by management actions have affected the ecological status of the lagoon, and (2) to discuss the suitability of several physicochemical and biological indicators for the assessment of the ecological status in this kind of coastal ecosystem.4. After the change in the hydrological regime, a general improvement of the ecological status was observed mainly as a result of the significant decrease in the nitrogen Trophic State Index and in the abundance of rotifer indicative of eutrophy, and in turn by the significant increase in the water quality index QAELS, based on crustaceans and insect assemblages.5. Contradictory results emerged with regard to some of the indicators used. After the hydrological change, the increase in the phosphorus Trophic State Index was related with the fact that Mediterranean confined coastal ecosystems are typically P-enriched. In contrast with general assumptions, low diversity and richness of the zooplankton and the dominance of a few species have been related with an improvement of the ecological status after the hydrological change, when freshwater inputs were reduced and the lagoon became more confined. Copyright (c) 2008 John Wiley & Sons, Ltd.

Differences in the dynamics of ecological processes between Mediterranean and colder temperate aquatic systems could imply different patterns in faunal communities in terms of composition and biodiversity (i.e. species richness and rarity). In order to identify some of these patterns the crustacean and aquatic insect composition and biodiversity of four water body types, classified according to their salinity and water permanence, were compared. Moreover, the relationships between species richness and water, pond and landscape variables were analysed. A total number of 91 water bodies located throughout Catalunya (NE Iberian Peninsula) were sampled. Three species assemblages were observed: one for permanent freshwaters, another for temporary freshwaters, and a third one for saline waters (SW), since permanent and temporary saline water bodies had similar composition. Differences in salinity were associated with proportion of crustaceans versus insects and with singularity. Thus, saline ponds had a higher proportion of crustaceans, and lower values of singularity. Conductivity was significantly related to total (crustaceans plus insects) richness, and also related to insect richness. The main difference between the models obtained for crustacean species richness and insect species richness is the significance of landscape variables in the latter, and this fact could be related to the different dispersion types of these two faunal groups: active for insects versus passive for crustaceans.

The Ter Vell (NE Iberian Peninsula) is a eutrophic coastal lagoon which has been flooded by the excess irrigation water and the agricultural runoff during the last decades. Between 1999 and 2003, restoration measures were applied to improve its water quality. At the same time, but independently, agricultural water management drastically reduced the freshwater inflow. The short-term effects of these management actions on the limnological characteristics of the lagoon were analysed by comparing two hydrological cycles, one before (1999/2000) and the other one after (2002/2003) the actions. The two cycles are illustrative of opposite situations in the hydrological functioning of coastal wetlands. In the first, the lagoon was exorheic, with prolonged flooding periods and a low residence time; in the second, it had a more endorheic character, with scarce water inputs and prolonged periods of confinement. Consequently, nitrogen inputs diminished and organic load and salinity increased as the internal loading and the accumulation effects became more relevant. These effects were actually caused by the drastic reduction in the freshwater inflow which prevented, in turn, the success of the restoration measures. The zooplankton community of the Ter Vell lagoon was not significantly altered by the hydrological change, at least in the short-term, and rotifers and cladocerans, mainly those species indicative of eutrophy, dominated the community.