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This study was seasonally performed over a three year period in a large freshwater temporary pond to investigate (a) seasonal trends of the main abiotic factors, (b) the most important abiotic drivers in shaping macrobenthic invertebrate communities and (c) the structures of these communities among different years. As the study area was placed within a Natural Reserve, the leaf bag technique was used as non invasive sampling method in order to reduce disturbance. The results of chemical and physical investigations point out a clear seasonal trend, while macrobenthic communities differ signifi cantly from year to year, and their main shape drivers were identifi ed to be conductivity, temperature and dissolved oxygen.

In aquatic ecosystems, the decomposition of organic detritus represents one of the most important ecosystem functions, which support complex detritus-based food webs that determine the critical balance between carbon mineralization and sequestration. The performance of the decomposition process is usually expressed as rate of decomposition, being a synthetic measure that take into account both abiotic and biotic factors. Decomposition rates have been also applied to evaluate the ecological status in terms of ecological functionality. However, despite a growing number of studies have tested the rate of decomposition between leaves of different riparian tree species in different aquatic ecosystems including rivers, transitional waters and sea, no comparative study among ecosystems typology is available up to date. Here, we compare decomposition rates from rivers, lagoons and sea of Corfu island (Greece). Five sampling sites were fixed in each of the three of the most important rivers and lagoons; other five sampling sites were fixed in the sea around the island. Twelve leaf packs containing 3±0.005 g of oven-dried Phragmites australis leaves were submerged in April 2014 and retrieved in May 2014 (after 30 days). Abiotic parameters were recorded in both sampling times. The retrieved leaf packs were cleaned and the macroinvertebrates retained were removed, counted, identified at lower taxonomic level and weighted. Leaf pack decomposition rates were calculated, and their variability was compared within each aquatic ecosystem, within each ecosystem typology (river, lagoon, sea) and among ecosystem typology. The results are going to be presented on the poster.

Mediterranean lagoons are exposed to natural and anthropogenic disturbances, and the most unlikely conditions are the dystrophic and hypoxic events. These events determine dis-equilibrium conditions along temporal and spatial scales, which are linked to metabolism and life cycle of the biotic components. In summer 2008, Lesina lagoon (SE Italian coastline) was interested by a geographically localized dystrophic crisis which affected up to 8% of the total lagoon surface. Temporal dynamics of principal descriptors of abiotic (water, sediment) and biotic (phytoplankton, benthic macroinvertebrate) compartments have been followed during the 2008 by collecting data inside stressed and control lagoon areas before a dystrophic event and in the six months after the dystrophic event. The aim of the study was to analyse the pathways of ecosystem responses to dystrophic stress, searching for the characteristic scales of ecosystem compartment resistance and resilience. The characteristic time-scale of abiotic and biotic component time responses varied from days, for the selected markers of the water column, to year, for the benthic ones. Short-term biotic and abiotic responses in the water column were strongly coupled while biotic and abiotic responses at the sediment level were remarkably un-coupled. Dynamics and recovery time of water column and benthic components do not match in Lesina following the dystrophic crisis, highlighting an intrinsic individualistic behavior within the lagoon community driving ecosystem processes and ecosystem level responses. Taxonomic and non-taxonomic descriptors of benthic macroinvertebrates showed different response patterns as early warning signals and overall resilience. The emphasized differences in the stability components, i.e., resistance and resilience, of water column and sediment abiotic and biotic characteristics as well as of taxonomic and nontaxonomic descriptors has key implication in planning monitoring strategies and programs for transitional waters in the Mediterranean EcoRegion.

1 - Mediterranean lagoons are naturally exposed, during the dry season, to dystrophic and hypoxic events determining dis-equilibrium conditions along temporal and spatial scales, which are linked to metabolism and life cycle of the biotic components. 2 - In summer 2008, Lesina lagoon (SE Italian coastline) was interested by a geographically localized dystrophic crisis which affected up to 8% of the total lagoon surface. 3 - Temporal dynamics of principal descriptors of abiotic (water, sediment) and biotic (phytoplankton, benthic macroinvertebrate) compartments have been followed during the 2008 by collecting data inside stressed and control lagoon areas before a dystrophic event and in the six months after the dystrophic event. 4 - The aim of the study was to analyse the pathways of ecosystem responses to dystrophic stress, searching for the characteristic scales of ecosystem compartment resistance and resilience. 5 - The characteristic time-scale of abiotic and biotic component time responses varied from days, for the selected markers of the water column, to year, for the benthic ones. Short-term biotic and abiotic responses in the water column were strongly coupled while biotic and abiotic responses at the sediment level were remarkably un-coupled. Dynamics and recovery time of water column and benthic components do not match in Lesina following the dystrophic crisis, highlighting an intrinsic individualistic behavior within the lagoon community driving ecosystem processes and ecosystem level responses. 6 - Taxonomic and non-taxonomic descriptors of both phytoplankton and benthic macroinvertebrates showed different response patterns as early warning signals and overall resilience. The emphasized differences in the stability components, i.e., resistance and resilience, of water column and sediment abiotic and biotic characteristics as well as of taxonomic and non-taxonomic descriptors has key implication in planning monitoring strategies and programs for transitional waters in the Mediterranean and Black Sea EcoRegions. © 2013 University of Salento - SIBA.

Abra segmentum is a common and frequently abundant species in the Mediterranean coastal lagoons, playing a dominant role, both in numbers and biomass, in the infauna of these habitats and is an important food for a variety of species. 2 - The main objective of this work is to describe the renewal time of Abra segmentum in Lesina lagoon. The insurgence of hydrogen sulphide which exterminated the benthic macrofauna in an area of Lesina lagoon during July 2008 allowed us to accurately observe the re-colonization time of this bivalve. In order to achieve this aim, the population structure and spatial distribution of A. segmentum before and after the dystrophic crisis were investigated in the entire Lesina lagoon and, in detail, in the area affected by the crisis. 3 - 51 sampling units were collected in Lesina lagoon in May and October 2008, allowing to compare the situation before and after the dystrophic crisis. The length-frequency distribution showed the existence of two size groups in both May and October 2008. The individuals were counted, their individual length measured and their total wet biomass weighed. 4 - The total number of individuals decreased after the crisis in the entire lagoon, but this drop was strongly observed in the perturbed area. The length-frequency distribution showed the existence of two size groups in both May and October 2008. After dystrophic crisis, the two size groups were clearly separated and juveniles group (2-5 mm) was located in the area interested by dystrophic event. 5 - The results obtained in this study highlight the rapidity of re-colonisation of A. segmentum after the strong disturbance caused by the insurgence of dystrophic crisis. The dynamics of the population was particularly clear when considering the area affected by the dystrophic crisis. In May the population was structured as in the rest of the lagoon, but in October there was a marked difference. The insurgence of a dystrophic crisis in Lesina lagoon allowed to clearly observe the resilience of A. segmentum to environmental stress, confirming it as an r strategy species.

1. We analyzed the dynamic of phytoplankton guild during an dystrophic crisis observed in an area of Lesina Lagoon from July to September 2008. 2. A two-weekly scale, patterns of variation of phytoplankton biomass (as Chla), numerical abundance, species richness, diversity, taxonomic and size structure were compared in two stations: one within the area affected by the crisis (AT2 station) and one outside, as control (AT3 station). 3. Phytoplankton biomass and cell abundance varied significantly between sampling stations and sampling times. Biomass was on average about 100 time higher in AT2 than AT3 station, with peaks of 180,67±22,12 mgChla/m3 (8 July) and 134,05±47,26 mgChla/m3 (5, September). Cell density was on average about 30 times higher in AT2 station, with values always higher than 20*106 cell/l. 4. Species richness and diversity did not varied significantly between stations and not show a trend with the evolution of anoxic crisis. 5. The taxonomic composition is similar in the two stations (taxonomic similarity among stations was 76,04%), even if the relative abundance of species was significantly different. 6. As regard size structure, in the AT2 station, microphytoplankton dominates at beginning of biomass bloom (dominant taxa: Thalassiosiraceae, average weight (AW) 163,51 pgC), whereas from the end of July until September and in the AT3 station, nanophytoplankton was the dominant fraction (dominant taxa: until the middle of August: Algae indet AW 3,14 pgC and Navicula sp. AW 2,50 pgC).

The Salento Lagoons site, a long-term ecological research site since 2014, comprises two transitional water ecosystems located on the southern coast of Apulia, Acquatina and Alimini, for which ecological data are available starting from 80s. Acquatina is a semi-artificial and oligotrophic basin with a surface area of 0.45 km2 and an average depth of 1.2 m. Alimini is a brackish and mesotrophic lagoon, located almost parallel to the Adriatic coastline, which covers a surface area of 1.37 km2 and has an average depth of 1.5 m. Both ecosystems are relatively pristine and of particular naturalistic interest, included in Sites of Community Importance of the "Natura 2000 Network" (IT9150003: "Acquatina Frigole; IT:9150011: "Laghi Alimini"). They also have a socio-economic role for the productive aspects related to fishing and tourist activities. Since 1985, the Acquatina basin has been managed by the Department of Biological and Environmental Sciences and Technologies (DISTEBA) of the University of Salento and is the focus of several scientific studies. The Alimini lake is subject of study by the Department of Biological and Environmental Sciences and Tecnologies of the University of Salento from more than 20 years and since 2008 it is also subject of monitoring activities, according to the requirements of the 2000/60/EC Water Framework Directive, by the Apulia Agency for Environmental Safety (ARPA-Puglia). The main research activities are focused on the study of ecology of phytoplankton, zooplankton, macrozoobenthos and fish fauna, with particular interest in composition and structure, functional traits, trophic interactions and invasive species.

The Salento Lagoons site, a long-term ecological research site since 2014, comprises two transitional water ecosystems located on the southern coast of Apulia, Acquatina and Alimini, for which ecological data are available starting from 80s. Acquatina is a semi-artificial and oligotrophic basin with a surface area of 0.45 km2 and an average depth of 1.2 m. Alimini is a brackish and mesotrophic lagoon, located almost parallel to the Adriatic coastline, which covers a surface area of 1.37 km2 and has an average depth of 1.5 m. Both ecosystems are relatively pristine and of particular naturalistic interest, included in Sites of Community Importance of the "Natura 2000 Network" (IT9150003: "Acquatina Frigole; IT:9150011: "Laghi Alimini"). They also have a socio-economic role for the productive aspects related to fishing and tourist activities. Since 1985, the Acquatina basin has been managed by the Department of Biological and Environmental Sciences and Technologies (DISTEBA) of the University of Salento and is the focus of several scientific studies. The Alimini lake is subject of study by the Department of Biological and Environmental Sciences and Tecnologies of the University of Salento from more than 20 years and since 2008 it is also subject of monitoring activities, according to the requirements of the 2000/60/EC Water Framework Directive, by the Apulia Agency for Environmental Safety (ARPA-Puglia). The main research activities are focused on the study of ecology of phytoplankton, zooplankton, macrozoobenthos and fish fauna, with particular interest in composition and structure, functional traits, trophic interactions and invasive species.

Predictions of individual responses to climate change are often based on the assumption that temperature affects the metabolism of individuals independently of their body mass. However, empirical evidence indicates that interactive effects exist. Here, we investigated the response of individual standard metabolic rate (SMR) to annual temperature range and forecasted temperature rises of 0.6–1.2°C above the current maxima, under the conservative climate change scenario IPCC RCP2.6. As a model organism, we used the amphipod Gammarus insensibilis, collected across latitudes along the western coast of the Adriatic Sea down to the southernmost limit of the species' distributional range, with individuals varying in body mass (0.4–13.57 mg). Overall, we found that the effect of temperature on SMR is mass dependent. Within the annual temperature range, the mass-specific SMR of small/young individuals increased with temperature at a greater rate (activation energy: E=0.48 eV) than large/old individuals (E=0.29 eV), with a higher metabolic level for high-latitude than low-latitude populations. However, under the forecasted climate conditions, the mass-specific SMR of large individuals responded differently across latitudes. Unlike the higher-latitude population, whose mass-specific SMR increased in response to the forecasted climate change across all size classes, in the lower-latitude populations, this increase was not seen in large individuals. The larger/older conspecifics at lower latitudes could therefore be the first to experience the negative impacts of warming on metabolism-related processes. Although the ecological collapse of such a basic trophic level (aquatic amphipods) owing to climate change would have profound consequences for population ecology, the risk is significantly mitigated by phenotypic and genotypic adaptation.

The present study provides energy density (ED) data and models for four macrobenthic invertebrate genera inhabiting freshwater lotic environments (Baetis, Hydropsyche, Rhyacophila, and Onychogomphus). Samples were collected in the hydrological freshwater network of the Region Friuli Venezia Giulia within different watercourse types (creeks, streams, rivers channels, and ditches), and energy density was directly measured using an adiabatic bomb calorimeter. Measured ED expressed in Joule g(-1) wet weight was strongly and positively correlated with percentage of dry weight (DW%) for all genera investigated (r(2) > 0.9504), allowing to obtain genus-specific predictive models based on the relationship between ED and DW%. Models were validated and showed good predictive power, as 90th percentile of observed percentage errors ranged between 4.23% and 5.18% while medians ranged between 1.32% and 2.83%. ANCOVA disclosed significant differences between the models, as those for Rhyacophila and Onychogomphus differed significantly from the others. The empirical models were used to build a dataset of estimated energy density, to assess the relationship between energy density and ecological status of the monitored riverine systems, assessed in compliance with European and Italian law by the application of four different ecological indices (ICMi, RQE_IBMR, STAR_ICMi, and LIMeco). Information regarding ED levels for freshwater macrobenthic invertebrates is still neglected in biomonitoring programs, but it could be useful to interpret some ecological situations in the context of ecological status assessment, especially in relation to the trophic condition of the investigated riverine systems.

Standard metabolic rate is a major functional trait with large inter-individual variability in many groups of aquatic species. Here we present results of an experimental study to address variation in standard metabolic rates, over different scales of organisation and environments, within a specific group of aquatic macro-invertebrates (i.e. gammarid amphipods) that represent the primary consumers in detritus food webs. The study was carried out using flow-through microrespirometric techniques on male specimens of three gammarid species from freshwater, transitional water and marine ecosystems. We examined individual metabolic rate variations at three scales: (1) at the individual level, during an 8 h period of daylight; (2) at the within-population level, along body-size and body-condition gradients; (3) at the interspecific level, across species occurring in the field in the three different categories of aquatic ecosystems, from freshwater to marine. We show that standard metabolic rates vary significantly at all three scales examined, with the highest variation observed at the within-population level. Variation in individual standard metabolic rates during the daylight hours was generally low (coefficient of variation, CV%) and unrelated to time. The average within-population CV ranged between 30.0 % and 35.0 %, with body size representing a significant source of overall inter-individual variation in the three species and individual body condition exerting only a marginal influence. In all species, the allometric equations were not as steep as would be expected from the 3∕4 power law, with significant variation in mass-specific metabolic rates among populations. The population from the transitional water ecosystem had the highest mass-specific metabolic rates and the lowest within-population variation. In the gammarid species studied here, body-size-independent variations in standard individual metabolic rates were higher than those explained by allometric body size scaling, and the costs of adaptation to short-term periodic variations in water salinity in the studied ecosystems also seemed to represent a major source of variation.

The metabolism of benthic aquatic invertebrates, populating transitional water ecosystems, is influenced by both physiological and environmental factors, thus involving an adjustment of physiological processes which has a metabolic cost. In order to discover changes in metabolic pathways in response to specific factors, it's firstly necessary characterizing the principal cellular metabolic activities of the small benthic aquatic organisms. We approach here the bioenergetic state issue of two benthic organisms, i.e. Lekanesphaera monodi and Gammarus insensibilis, evidencing that no apparent and statistically significative differences between them in aerobic as well in glycolytic capacities are detected, except for COX activity.

The present study is an attempt to deepen the knowledge about energy patterns in a detritus-based ecosystem located within a temporary wetland, where changes of water level can affect productivity, turnover of organic matter and the flow-through energy. Energy density was directly measured using an adiabatic bomb calorimeter in samples collected in autumn, spring and summer. Dipterans belonging to the genus Chironomus were the most common and representative invertebrates within the study area. Starting from these measures, a predictive model based on the relationship between energy density and percentage of dry weight was developed, validated and applied to build a multi-annual dataset. This model was used to investigate seasonal energy density trends on longer time-scale, in relation to physical and chemical features, weather conditions and decomposition dynamics. The used approach allowed to build a 3-year dataset and to identify clear seasonal trends; moreover, the application of the model highlighted patterns in relation to precipitation regime, decomposition dynamics and the effects due to variations of these features in the investigated temporary detritus-based system over a multi-annual scale.

Wetlands are one of the most biologically productive ecosystems, in which reedbeds of Phragmites australis are an essentially detritus-based system where litter decomposition is a fundamental process. This study represents a three year dataset describing cyclic trends of Phragmites australis leaf litter breakdown in a temporary and managed environment. For three years, 45 days field experiments were seasonally performed, using leaf bag technique within a large managed temporary pond (Natural Reserve of the Isonzo River Mouth, Northeast Italy), in order to analyze spatial and temporal variation in decomposition processes, to search for patterns on seasonal and inter-annual time scale and to infer the relevance of the main environmental features (physical and chemical) on decomposition dynamic. During the three years of analysis, decay rates (k) ranges were 0.0066–0.0075 days-1 in autumn, 0.0108–0.0158 days-1 in spring and k = 0.0168 days-1 in summer. Average mass loss per day % range was 0.97–1.31% in autumn, 1.12–2.04% in spring and 1.79–2.06% in summer. A well-defined seasonal cycle was observed through the study years as result of the drought-reflooding dynamic and the highest percentage (91.1%) of the average mass loss per day % variability was explained above all by rainfall, temperature and conductivity.

Increasing anthropogenic pressures are causing long-lasting regime shifts from high-diversity ecosystems to low-diversity degraded ones. Understanding the effects of multiple threats on ecosystems, and identifying processes allowing for the recovery of biodiversity, are the current major challenges in ecology. In several temperate marine areas, large parts of rocky subtidal habitats characterised by high diversity have been completely degraded to barren grounds by overfishing, including illegal date mussel fishing. Bare areas are characterized by the dominance of sea urchins whose grazing perpetuates the impact of overfishing. We investigated experimentally the separate and combined effects of nutrient enrichment and sea urchin exclusion on the recovery of barren grounds. Our results indicate that the two factors have a synergistic effect leading to the re-establishment of erect macroalgal canopies, enhancing the structural complexity of subtidal assemblages. In particular, in the overfished system considered here, the recovery of disturbed assemblages could occur only if sea urchins are removed. However, the recolonization of barren grounds by erect macroalgae is further enhanced under enriched conditions. This study demonstrates that the recovery of dramatically depleted marine habitats is possible, and provides useful indications for specific management actions, which at present are totally lacking, to achieve the restoration of barren grounds caused by human activity.

Morphological and physiological characteristics of the European eel (Anguilla anguilla) intestine were analyzed in two different stages (yellow and silver) of the fish ontogenic development. Intestine/body (Wi/Wa) and scraped mucosa/intestine (Wsc/Wi) wet weight ratios were significantly (P < 0.01) reduced in seawater acclimated silver eels compared to yellow ones. Electrogenic, Na+-dependent transport rates of a number of nutrients (D-glucose, L-proline, β-alanine, L-phenylalanine, L-methylalanine) were indirectly measured in intestinal brush border membrane vesicles of seawater acclimated eels, by monitoring the fluorescence quenching of the electrical membrane potential sensitive dye 3,3′-diethylthiocarbocyanine iodide [Dis-C2(5)], and were significantly lower (P < 0.05 for L-proline; P < 0.01 for all the others) in silver eels compared to yellow ones. The transepithelial electrical potential difference (Vt) and short-circuit current (Isc), measured by applying the short-circuit current technique to “in vitro” isolated intestine, were significantly higher in silver eels compared to yellow ones in both sea- and freshwater. The addition of 10−5 M bumetanide, inhibitor of the Na+-K+-2Cl− cotransporter, to the mucosal bathing solution almost completely abolished Vt and Isc in either yellow or silver eels intestine acclimated to both seawater and freshwater. Further, by using the microelectrode technique, it was shown that the apical membrane potential (Vm) averaged -27.3 ± 2.3 mV in yellow eels and -42.9 ± 3.3 mV in silver eels (P = 0.02). It is concluded that the changes in morphological (mucosal weight) and physiological (nutrient transport rates and electrophysiological parameters) characteristics found in silver compared to yellow eel intestine could represent adaptative features preparatory to the onset of the prolonged marine migration of the silver eel. © 1996 Wiley-Liss, Inc.

Regulation of metabolism is a common strategy used by individuals to respond to a changing environment. The mechanisms underlying the variability of metabolic rates in macroinvertebrates are of primary importance in studying benthic–pelagic energy transfer in transitional water ecosystems. Lekanesphaera monodi is an isopod endemic to transitional water ecosystems that can modify its metabolic rate in response to environmental changes. Therefore it is a useful model in studying the influence of environmental factors on metabolism. This study focused on the interpopulation variability of standard metabolic rates (SMR) in L. monodi populations sampled in three transitional water ecosystems differing in their trophic status. The standard metabolic rates of L. monodi individuals across the same range of body size spectra were inferred from oxygen consumption measurements in a flow-through respirometer in the three populations and a body condition index was assessed for each population. Habitat trophic status was evaluated by monthly measurement of the basic physical–chemical parameters of the water column in the ecosystems for one year. Standard metabolic rates showed high variability, ranging from 0.27 to 10.14 J d −1 . Body size accounted for more than 38% of total variability. In terms of trophic status, individuals from the eutrophic ecosystem had significantly higher standard metabolic rates than individuals from the other ecosystems (SMR = 2.3 J d −1 in Spunderati Sud vs. 1.36 J d −1 in Alimini and 0.69 J d −1 in Acquatina). The body conditions index was also higher in the population from the eutrophic ecosystem. Results show that standard metabolic rates and growth rates are directly related to habitat productivity in accordance with the expectations of the food habits hypothesis. A possible extension of this hypothesis to benthic invertebrates is proposed.

Lagoons are vulnerable ecosystems often exposed to eutrophication due to anthropogenic activities. They are characterized by high vulnerability to climatic factors and biogeochemical impairment that, in some cases, can lead to dystrophic crisis. 2 - Here we analyze the short term temporal pattern of climatic, physical and chemical parameters during a dystrophic crisis occurred in Lesina lagoon in Summer 2008, focusing on the interactive effect of their variations. 3 - To this aim, we integrated meteorological data, satellite image analysis and local physical and chemical measurements in order to have a more detailed sight of processes that can give raise to a dystrophic crisis and to describe how the crisis evolves. 4 - Results show that an unusual change in main wind direction, sun radiation, and other meteorological parameters with respect to the previous years together with a temporal closing of tidal channel that assure the seawater inflow led to an hydrologic isolation of the western basin of Lesina lagoon occurred in summer 2008. The consequent unbalance in biogeochemical cycles produced a dystrophic crisis and a shift, in this area, from a macrophytes based system toward a phytoplankton based system. 5 - Since changes in climatic factors or in hydrologic regimes into the eutrophic lagoon probably already happened previously in different moments without giving rise to dystrophic event, the crisis was likely triggered by the co-occurrence of both factor variations. 6 - It is essential to understand the mechanistic linkages in space and time between man-made alterations of hydrologic and nutrient load regimes (that can be managed or controlled) and unpredictable climatic factors in the context of the individual ecosystem for managing transitional water ecosystems incurring in nutrient enrichment.