Un mundo cada vez más salado

La actividad humana está provocando la salinización de ríos, lagos y otros sistemas acuáticos. Este fenómeno afecta a la calidad de las aguas y tiene graves consecuencias para los seres vivos

COLONIZATION PROCESS IN NEW CREATION MEDITERRANEAN COASTAL LAGOONS

The colonization process in new creation Mediterranean salt marsh lagoons is influenced by hydrological fluctuations characterised by flooding-confinement periods. This pattern has direct effects on water characteristics (such as nutrient concentration), but it also effects the connectivity structure between lagoons impacting main metacommunity dynamics. Unfortunately, these ecosystems have suffered transformations due to urbanization process that has contributed to its degradation. This is the case of La Pletera salt marshes, located in the NE of Catalonia, in where a recovery and restoration European LIFE project (LIFE13 NAT/ES/001001) that included the restoration of existing lagoons and the creation of new ones has been done. In this study, we analysed the structure of aquatic macrofauna community of these new created lagoons just after its creation and five years after its creation with the aim of assessing the colonization assembly process. Our results showed a fast colonization of the species with active dispersion since they dominated the communities right after lagoon creation (Diptera). In contrast, species with passive dispersion (Gastropoda and Amphipoda) that have a lower dispersive capacity were dominant at the last sampling survey, 5 years after creation. This could be explained by flooding periods that connect all wetland waterbodies favouring the arrival of both, active and passive dispersers. Moreover, we observed an increase in the abundance and biomass of taxa with lower dispersion capacity but without affecting the overall community richness values

Local hydrological conditions and spatial connectivity shape invertebrate communities after rewetting in temporary rivers

Temporary rivers (TRs) dominate global river networks and are increasing in occurrence and spatiotemporal extent. However, few studies have investigated the communities that establish after rewetting events (i.e. the end of the dry phase), when local hydrological conditions can shape the communities through species sorting, and the spatial connectivity of sites can also influence colonisation. Here, we analysed the relative importance of both local hydrological conditions and spatial connectivity on the invertebrate communities of seven not impacted Mediterranean TRs after rewetting. We quantified the frequency and duration of drying events and the time since flow resumed. We also quantified spatial connectivity based on each site's position in the river network (i.e. network connectivity) and the presence of nearby disconnected streams. Overall, we found that both hydrological conditions and network connectivity played a significant role in structuring aquatic invertebrate communities after rewetting. Taxonomic richness, functional richness and functional redundancy decreased with the frequency and duration of drying events and increased with time since the most recent rewetting. Network connectivity showed a significant unimodal relationship with taxonomic and functional metrics. In contrast, the presence of nearby disconnected streams was negatively related to functional richness and functional dispersion. Given that flow intermittence in Mediterranean areas is expected to intensify under future global change scenarios, our results can be helpful to guide future conservation and management actions

Navigating through space and time: A methodological approach to quantify spatiotemporal connectivity using stream flow data as a case study

1. The growing interest in combining spatial and temporal patterns in nature has been fostered by the current availability of high-frequency measurements. However, we still lack a methodological framework to process and interpret spatiotemporal datasets into meaningful values, adaptable to different time windows and/or responding to different spatial structures. Here, we developed and tested a framework to evaluate spatiotemporal connectivity using two new measures: the spatiotemporal connectivity (STcon) and the spatiotemporal connectivity matrix (STconmat). 2. To obtain these measures, we consider a set of spatially connected sites within a temporally dynamic network. These measures are calculated from a spatiotemporal matrix where spatial and temporal connections across sites are captured. These connections respond to a determined network structure, assign different values to these connections and generate different scenarios from which we obtain the spatiotemporal connectivity. We developed these measures by using a dataset of stream flow state spanning a 513-day period obtained from data loggers installed in seven temporary streams. These measures allowed us to characterise connectivity among stream reaches and relate spatiotemporal patterns with macroinvertebrate community structure and composition. 3. Spatiotemporal connectivity differed within and among streams, with STcon and STconmat capturing different hydrological patterns. Macroinvertebrate richness and diversity were higher in more spatiotemporally connected sites. Community dissimilarity was related to STconmat showing that more spatiotemporally connected sites had similar communities for active and passive dispersers. Interestingly, both groups were related to spatiotemporal connectivity patterns for some of the analysed scenarios, highlighting the relevance of spatiotemporal connectivity in dynamic systems. 4. As we exemplified, the proposed framework can help to disentangle and quantify spatiotemporal dynamics or be applied in the conservation of dynamic systems such as temporary streams. However, the current framework is not limited to the temporal and spatial features of temporary streams. It can be extended to other ecosystems by including different time windows and/or consider different network structures to assess spatiotemporal patterns. Such spatiotemporal measures are especially relevant in a context of global change, with the spatiotemporal dynamics of ecosystems being heavily disrupted by human activities.info:eu-repo/semantics/publishedVersio

ECOLOGICAL RESTORATION PROMOTES ZOOPLANKTON NETWORK COMPLEXITY IN MEDITERRANEAN COASTAL LAGOONS

Ecological recovery following restoration is typically evaluated using metrics based on species diversity and composition. However, increasing evidence suggests the success of long-term ecological recovery is better evaluated when more complex attributes such as biotic interaction networks are targeted. For example, at the beginning the influence of nearby habitats can promote colonization leading to similar communities in restored or newly created lagoons, but communities often diverge from surrounding water bodies at later successional stages. These changes have been attributed to the effect of biotic interactions, but few studies have tested this assumption. Here, we analyse the zooplankton community of a Mediterranean coastal wetland subjected to a restoration process that involved the creation of new lagoons. We analysed community dissimilarity patterns and used mixed graphical models to infer interaction networks from abundance data. Increasing differences in the community structure between new and old lagoons were detected from the second year after their creation. The overall interaction network was more complex in new than in old lagoons. Interestingly, the network structure in old lagoons increased its complexity three years after restoration. We show how the inclusion of interaction networks for the monitoring of ecosystem recovery reflects unique facets of community complexity, otherwise overlooked when targeting diversity metrics alone

Heterogeneity in the isolation of patches may be essential for the action of metacommunity mechanisms

The spatial isolation gradient of communities and the gradient in the species dispersal ability are recognized as determinants of biodiversity in metacommunities. In spite of this, mean field models, spatially explicit models, and experiments were mainly focused on idealized spatial arrangements of communities leaving aside the combining role of dispersal and isolation gradients in metacommunity processes. Consequently, we have an incipient understanding of the role of the real spatial arrangement of communities on biodiversity patterns. We focus on six metacommunities for which confident information about the spatial arrangement of water bodies is available. Using coalescent metacommunity models and null models that randomize the location of water bodies, we estimated the potential eect of the landscape on biodiversity and its dependence on species dispersal ability. At extremely lowor high dispersal abilities, the location of ponds does not influence diversity because dierent communities are equally aected by the low or high incoming dispersal. At intermediate dispersal abilities, peripheral communities present a much lower richness and higher beta diversity than central communities.Moreover,metacommunities from real landscapes host more biodiversity than randomized landscapes, a result that is determined by the heterogeneity in the geographic isolation of communities. In a dispersal gradient, mass eects systematically increase the local richness and decrease beta diversity. However, the spatial arrangement of patches only has a large importance in metacommunity processes at intermediate dispersal abilities, which ensures access to central locations but limits dispersal in isolated communities. The ongoing reduction in spatial extent and simplification of the landscape may consequently undermine the metacommunity processes that support biodiversity, something that should be explicitly considered in preserving and restoring strategies

Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments

The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations

Defining the importance of landscape metrics for large branchiopod biodiversity and conservation: the case of the Iberian Peninsula and Balearic Islands

The deficiency in the distributional data of invertebrate taxa is one of the major impediments acting on the bias towards the low awareness of its conservation status. The present study sets a basic framework to understand the large branchiopods distribution in the Iberian Peninsula and Balearic Islands. Since the extensive surveys performed in the late 1980s, no more studies existed updating the information for the whole studied area. The present study fills the gap, gathering together all available information on large branchiopods distribution since 1995, and analysing the effect of human population density and several landscape characteristics on their distribution, taking into consideration different spatial scales (100 m, 1 km and 10 km). In overall, 28 large branchiopod taxa (17 anostracans, 7 notostracans and 4 spinicaudatans) are known to occur in the area. Approximately 30% of the sites hosted multiple species, with a maximum of 6 species. Significant positive co-occurring species pairs were found clustered together, forming 4 different associations of large branchiopod species. In general, species clustered in the same group showed similar responses to analysed landscape characteristics, usually showing a better fit at higher spatial scales.Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq [401045/2014-5]Spanish Ministry of Education, Culture and Sport [FPU014/06783]info:eu-repo/semantics/publishedVersio

Resilience of aquatic metacommunities: implications for disturbance recovery

During the last years, there has been an increase in the number and intensity of disturbances, and their consequences related with global change, which have corroborated the already forecasted scenarios. One example are wildfires, which are expected to increase both in intensity and extension in the near future. However, although the extensive research carried out to understand wildfire impacts, there is still a lack of knowledge regarding its consequences on freshwater temporary ponds. These temporary habitats constitute small biodiversity reservoirs, holding singular and iconic fauna. Nowadays, these habitats are endangered mostly due to habitat loss. Consequently, to cope with the future climatic scenario, which predicts an increase in wildfire disturbances as well as greater habitat loss, it becomes mandatory to better comprehend and study wildfire impacts on these small biodiversity jewels.Throghout this thesis I study the Jonquera wildfire consequences on the Albera temporary pondsDurant els últims anys, l’increment de pertorbacions lligades al context de canvi global està corroborant cada dia els pronòstics més negatius. En aquesta mateixa línia, i en relació a les pertorbacions d’abast regional com els incendis, les prediccions no fan res més que pronosticar-ne un augment, tant en la intensitat com en l’extensió. Tanmateix, tot i la gran quantitat de recerca sobre els impactes dels incendis se sap poc en relació al seu impacte sobre els estanys temporanis d’aigua dolça. Aquests, constitueixen un reservori de biodiversitat únic i molt valuós en les regions com la Mediterrània i actualment es troben greument amenaçats a causa de la seva desaparició. En conseqüència, davant de les futures perspectives climàtiques d’increment dels incendis i d’una major pèrdua d’habitat, esdevé cabdal conèixer quins són els impactes dels incendis sobre els estanys temporanis mediterranis. En aquesta tesi s'aprofundeix en els afectes de l'incendi de la Jonquera sobre els estanys temporanis de l'Alber

The effects of longitudinal fragmentation on riverine beta diversity are modulated by fragmentation intensity

The loss of longitudinal connectivity affects river systems globally, being one of the leading causes of the freshwater biodiversity crisis. Barriers alter the dispersal of aquatic organisms and limit the exchange of species between local communities, disrupting metacommunity dynamics. However, the interplay between connectivity losses due to dams and other drivers of metacommunity structure, such as the configuration of the river network, needs to be explored. In this paper, we analyzed the response of fish communities to the network position and the fragmentation induced by dams while controlling for human pressures and environmental gradients. We studied three large European catchments covering a fragmentation gradient: Upper Danube (Austrian section), Ebro (Spain), and Odra/Oder (Poland). We quantified fragmentation through reach-scaled connectivity indices that account for the position of barriers along the dendritic network and the dispersal capacity of the organisms. We used generalized linear models to explain species richness and Local Contributions to Beta Diversity (LCBD) and multilinear regressions on the distance matrix to describe Beta Diversity and its Replacement and Richness Difference components. Results show that species richness was not affected by fragmentation. Network centrality metrics were relevant drivers of beta diversity for catchments with lower fragmentation (Ebro, Odra), and fragmentation indices were strong beta diversity predictors for the catchment with higher fragmentation (Danube). We conclude that in highly fragmented catchments, the effects of network centrality/isolation on biodiversity could be masked by the effects of dam fragmentation. In such catchments, metapopulation and metacommunity dynamics can be strongly altered by barriers, and the restoration of longitudinal connectivity (i.e. the natural centrality/isolation gradient) is urgent to prevent local extinctions.The authors are thankful to Mark Padgham for the useful hints on improving ‘riverconn’ execution over large networks, Libor Zavorka for the useful suggestions on invasive species, the Polish Chief Inspectorate for Environmental Protection (GIOŚ) for providing the fish dataset for the Odra, and Robert Ptacnik for the statistics suggestions.Peer reviewe