Potential use of ecotoxicological biomarkers in Serratella ignita (Ephemeroptera) larvae for Alcantara river (Sicily, Italy) water quality assessment

Benthic macroinvertebrates are important components of aquatic river ecosystems. These organisms are often used for biological monitoring since they are good indicators of the aquatic freshwater environment health status which can be negatively affected by human, agricultural and industrial activities. Many studies focused on the use of observed changes in macroinvertebrate communities or populations, but studies using biochemical biomarkers in these species are almost absent. The aim of this paper was to test the employment of ecotoxicological biomarkers in Ephemeroptera larvae to assess the water quality of the Alcantara river (Sicily) from its headwater to its mouth. This river represents the main source of potable water for all the counties situated in the Alcantara valley and for the city of Messina, and is the primary irrigation source for the large surrounding agricultural lands. Acetylcholinesterase activity (AChE) and Benzo(a)pyrene monooxygenase (BPMO) activity were evaluated in Serratella ignita (Ephemerellidae) larvae from different sampling sites along the river to show the potential presence of xenobiotic substances. Environmental parameters, such as temperature, dissolved oxygen, pH, conductivity and flow velocity, were also measured at different sampling sites. The biomarker approach in invertebrates represents an early warning signal of ecotoxicological alterations, providing information on which contaminants exert toxic effects on different biota. The results showed that the highest inhibition of AChE activity in S. ignita larvae was in Randazzo and Castiglione di Sicilia villages (i.e. high and medium level of the river). Here, agricultural activities are intense, with high production of fruit, olives, citrus and the heaviest usage of fertilizers, pesticides, and neurotoxic substances like organophosphate insecticides and carbammates in all the Alcantara valley. Regarding BPMO activity, the highest value was recovered in S. ignita larvae from the river mouth, which was characterised by the highest entry of water run off of streets and loaded with xenobiotic lipophilic compounds. Both AChE and BPMO were not linked to water temperature values. The data reported in the present work represent the first attempt to monitor levels of two widely recognised enzymatic biomarkers in benthic macroinvertebrates. Results indicate the possible use of this approach in macroinvertebrate larvae to study the health status of Alcantara river. The river appears to be impacted by contamination mainly from waste discharges and, upstream, from large pasture areas. Considering the world-wide distribution of S. ignita, the biomarker approach used to assess water quality may be applicable not only to Alcantara river, but also to other lotic ecosystems

Horizontal distribution of deep sea microplankton: A new point of view for marine biogeography.

An investigation on microplankton composition and spatial distribution has been carried out around Italian seas. The analysis of 53 samples, collected in 2017 at two depths in 27 different stations, has led to a scenario of horizontal distribution of microplankton. Dinophyta and Ciliophora were chosen as representatives of the whole microplankton community. A total of 60 genera were identified. Cluster analysis of data regarding taxa presence and abundance led us to recognize that similarities between surface stations were more evident than those between deep ones. Furthermore, we conducted an inter-annual comparison with available data from the South Adriatic Sea (2013, 2015). The higher dissimilarity between deep sea samples was also confirmed in a relatively smaller geographic area. The dissimilarity of deep-sea samples does not correspond to a higher habitat diversification, in terms of abiotic parameters. It has been suggested that the negligible biological connectivity in the deep, for those micro-organisms not able to perform wide spatial migrations, could produce such a biological diversificatio

THE STRAIT OF MESSINA: A KEY AREA FOR PELAGIA NOCTILUCA (CNIDARIA, SCYPHOZOA)

The Strait of Messina is certainly a focal area for the biological cycle of the jellyfish Pelagia noctiluca in the Western Mediterranean Sea. By means of both original and literature data, a conceptual model outlining the biological cycle of this species is proposed. P. noctiluca reproduces from late winter to late spring in the Aeolian Island Archipelago. From late spring to early summer, currents transport newly produced young individuals (20-30 mm bell diameter) eastwards, towards the Strait. The Strait of Messina ecosystem is not a suitable reproduction area for its intense hydrodynamism that would surely lead to a very low reproductive success due to gamete dispersion. This area, however, represents an optimal site for growth, due to its intensive primary and secondary production, but also for an optimal temperature range, lower in summer and higher in winter in respect to the surrounding basins. Pelagia remains all the summer inside the Strait, increasing in bell diameter (50-70 mm) and biomass. Subsequently, in late summer-early autumn, the mature specimens, taking advantage of a typical autumnal downwelling transport, move to deep Tyrrhenian waters where overwinter, to upwell in the Aeolian Archipelago by late winter to start a new cycle

Biological responses to change in Antarctic sea ice habitats

Sea ice is a key habitat in the high latitude Southern Ocean and is predicted to change in its extent, thickness and duration in coming decades. The sea-ice cover is instrumental in mediating ocean–atmosphere exchanges and provides an important substrate for organisms from microbes and algae to predators. Antarctic krill, Euphausia superba, is reliant on sea ice during key phases of its life cycle, particularly during the larval stages, for food and refuge from their predators, while other small grazers, including copepods and amphipods, either live in the brine channel system or find food and shelter at the ice-water interface and in gaps between rafted ice blocks. Fish, such as the Antarctic silverfish Pleuragramma antarcticum, use platelet ice (loosely-formed frazil crystals) as an essential hatching and nursery ground. In this paper, we apply the framework of the Marine Ecosystem Assessment for the Southern Ocean (MEASO) to review current knowledge about relationships between sea ice and associated primary production and secondary consumers, their status and the drivers of sea-ice change in this ocean. We then use qualitative network modelling to explore possible responses of lower trophic level sea-ice biota to different perturbations, including warming air and ocean temperatures, increased storminess and reduced annual sea-ice duration. This modelling shows that pelagic algae, copepods, krill and fish are likely to decrease in response to warming temperatures and reduced sea-ice duration, while salp populations will likely increase under conditions of reduced sea-ice duration and increased number of days of >0°C. Differences in responses to these pressures between the five MEASO sectors were also explored. Greater impacts of environmental pressures on ice-related biota occurring presently were found for the West and East Pacific sectors (notably the Ross Sea and western Antarctic Peninsula), with likely flow-on effects to the wider ecosystem. All sectors are expected to be impacted over coming decades. Finally, we highlight priorities for future sea ice biological research to address knowledge gaps in this field

Biological responses to change in Antarctic sea ice habitats

Sea ice is a key habitat in the high latitude Southern Ocean and is predicted to change in its extent, thickness and duration in coming decades. The sea-ice cover is instrumental in mediating ocean–atmosphere exchanges and provides an important substrate for organisms from microbes and algae to predators. Antarctic krill, Euphausia superba, is reliant on sea ice during key phases of its life cycle, particularly during the larval stages, for food and refuge from their predators, while other small grazers, including copepods and amphipods, either live in the brine channel system or find food and shelter at the ice-water interface and in gaps between rafted ice blocks. Fish, such as the Antarctic silverfish Pleuragramma antarcticum, use platelet ice (loosely-formed frazil crystals) as an essential hatching and nursery ground. In this paper, we apply the framework of the Marine Ecosystem Assessment for the Southern Ocean (MEASO) to review current knowledge about relationships between sea ice and associated primary production and secondary consumers, their status and the drivers of sea-ice change in this ocean. We then use qualitative network modelling to explore possible responses of lower trophic level sea-ice biota to different perturbations, including warming air and ocean temperatures, increased storminess and reduced annual sea-ice duration. This modelling shows that pelagic algae, copepods, krill and fish are likely to decrease in response to warming temperatures and reduced sea-ice duration, while salp populations will likely increase under conditions of reduced sea-ice duration and increased number of days of >0°C. Differences in responses to these pressures between the five MEASO sectors were also explored. Greater impacts of environmental pressures on ice-related biota occurring presently were found for the West and East Pacific sectors (notably the Ross Sea and western Antarctic Peninsula), with likely flow-on effects to the wider ecosystem. All sectors are expected to be impacted over coming decades. Finally, we highlight priorities for future sea ice biological research to address knowledge gaps in this field

Potential use of ecotoxicological biomarkers in Serratella ignita (Ephemeroptera) larvae for Alcantara river (Sicily, Italy) water quality assessment

Benthic macroinvertebrates are important components of aquatic river ecosystems. These organisms are often used for biological monitoring since they are good indicators of the aquatic freshwater environment health status which can be negatively affected by human, agricultural and industrial activities. Many studies focused on the use of observed changes in macroinvertebrate communities or populations, but studies using biochemical biomarkers in these species are almost absent. The aim of this paper was to test the employment of ecotoxicological biomarkers in Ephemeroptera larvae to assess the water quality of the Alcantara river (Sicily) from its headwater to its mouth. This river represents the main source of potable water for all the counties situated in the Alcantara valley and for the city of Messina, and is the primary irrigation source for the large surrounding agricultural lands. Acetylcholinesterase activity (AChE) and Benzo(a)pyrene monooxygenase (BPMO) activity were evaluated in Serratella ignita (Ephemerellidae) larvae from different sampling sites along the river to show the potential presence of xenobiotic substances. Environmental parameters, such as temperature, dissolved oxygen, pH, conductivity and flow velocity, were also measured at different sampling sites. The biomarker approach in invertebrates represents an early warning signal of ecotoxicological alterations, providing information on which contaminants exert toxic effects on different biota. The results showed that the highest inhibition of AChE activity in S. ignita larvae was in Randazzo and Castiglione di Sicilia villages (i.e. high and medium level of the river). Here, agricultural activities are intense, with high production of fruit, olives, citrus and the heaviest usage of fertilizers, pesticides, and neurotoxic substances like organophosphate insecticides and carbammates in all the Alcantara valley. Regarding BPMO activity, the highest value was recovered in S. ignita larvae from the river mouth, which was characterised by the highest entry of water run off of streets and loaded with xenobiotic lipophilic compounds. Both AChE and BPMO were not linked to water temperature values. The data reported in the present work represent the first attempt to monitor levels of two widely recognised enzymatic biomarkers in benthic macroinvertebrates. Results indicate the possible use of this approach in macroinvertebrate larvae to study the health status of Alcantara river. The river appears to be impacted by contamination mainly from waste discharges and, upstream, from large pasture areas. Considering the world-wide distribution of S. ignita, the biomarker approach used to assess water quality may be applicable not only to Alcantara river, but also to other lotic ecosystems

Three-Dimensional Quantification of Copepods Predictive Distributions in the Ross Sea: First Data Based on a Machine Learning Model Approach and Open Access (FAIR) Data

Zooplankton is a fundamental group in aquatic ecosystems representing the base of the food chain. It forms a link between the lower trophic levels with secondary consumers and shows marked fluctuations in populations with environmental change, especially reacting to heating and water acidification. Marine copepods account for approx. 70% of the abundance of zooplankton and are a target of monitoring activities in key areas such as the Southern Ocean. In this study, we have used FAIR-inspired legacy data (dating back to the 1980s) collected in the Ross Sea by the Italian National Antarctic Program at GBIF.org. Together with other open-access GIS data sources and tools, it allows one to generate, for the first time, three-dimensional predictive distribution maps for twenty-six copepod species. These predictive maps were obtained by applying machine learning techniques to grey literature data, which were visualized in open-source GIS platforms. In a Species Distribution Modeling (SDM) framework, we used machine learning with three types of algorithms (TreeNet, RandomForest, and Ensemble) to analyze the presence and absence of copepods in different areas and depth classes as a function of environmental descriptors obtained from the Polar Macroscope Layers present in Quantartica. The models allow, for the first time, to map-predict the food chain per depth class in quantitative terms, showing the relative index of occurrence (RIO) in 3Dimensions and identifying the presence of each copepod species analyzed in the Ross Sea, a globally-relevant wilderness area of conservation concern. Our results show marked geographical preferences that vary with species and trophic strategy. This study demonstrates that machine learning is a successful method in accurately predicting the Antarctic copepod presence, also providing useful data to orient future sampling and the management of wildlife and conservation

Observing and modeling long-term persistence of P. noctiluca in coupled complementary marine systems (Southern Tyrrhenian Sea and Messina Strait)

In the Mediterranean Sea, the Strait of Messina (MS) is a very peculiar area, connecting highly different regions and representing a privileged observatory for an early comprehension and assessment of ecosystems shifts. It is hypothesized that the outbreaks observed near the coast of many sites in the Mediterranean Sea may be the result of transport of permanent populations of P. noctiluca in pelagic waters to the coast, caused by specific hydrodynamic conditions. By both visual observations and numerical experiments our objective is twofold: (A) to help clarify whether the basin of the Aeolian Islands Archipelago (AIA), in the Southern Tyrrhenian Sea (STS), may be the site from which large populations of P. noctiluca are transported to the MS, and (B) to evaluate whether the upwelling turbulent system of the MS can be an energetic opportunity for this species. It should offer a rich habitat without jeopardizing the overall survival of the population, that is subject to stranding due to strong currents. Although very different, the two involved ecosystems (AIA and MS ) are complementary for the success of Pelagia noctiluca life cycle. Outputs obtained by coupling the 3D hydrodynamic model (SHYFEM) with a Lagrangian particle tracking model support the hypothesis of a connectivity between these two ecosystems, particularly in the first half of the year, indicating the coastal areas around the AIA as potential optimal source location for Pelagia larval stages. We support the very attractive hypothesis that two connected systems exist, the former one favours Pelagia\u27s reproduction and acts as a nursery and the latter favours its growth due to higher productivity. We speculate that the reproductive population of the AIA is not permanent, but is renewed every year by individuals who have fed and quickly grown in the MS and who are passively transported by downwelling along canyon "corridors"

Biomarkers employment in planktonic copepods for early management and conservation of aquatic ecosystems: the case of the 'Capo Peloro' lakes (southern Italy)

Transitional water ecosystems can be exposed to high levels of anthropic pressure. The main aim of this study was to present the 'Capo Peloro' lakes (southern Italy) case study, which highlights the advantageous use of ecotoxicological biomarkers in key copepod species, to reveal potential contamination in transitional water ecosystems. The focus was on changes that occur after the summer season, as during the summer, the surrounding human population increases significantly, with the consequent enhancement of anthropic pressures. Biomarkers were defined to monitor the zooplankton copepods Paracartia latisetosa, Acartia tonsa and Oithona brevicornis. Acetylcholinesterase, lipid peroxidation, and benzo(a)pyrene-monooxygenase activities were determined. P. latisetosa, A. tonsa and O. brevicornis show linear increases in their acetylcholinesterase activities with increasing concentrations in sample homogenates, which defines their high metabolic rates, and thus the suitability of these species as bioindicators. Biochemical alterations in these species induce changes in their biological attributes that can also lead to their disappearance, with a cascade of consequences for the higher trophic levels in the food chain. These data indicate that for the two lakes of Capo Peloro there is contamination by pesticides, carbamates and polycyclic and polyhalogenated aromatic hydrocarbons. This occurs mainly at the end of the summer season, and only affects the species of the low trophic levels. This case study shows the benefits provided by this biomarker approach as applied to zooplankton species, to monitor transitional water ecosystems and to estimate their toxicological risk, and thus to provide an early warning signal for loss of ecosystem integrity

Machine learning applied to species occurrence and interactions: the missing link in biodiversity assessment and modelling of Antarctic plankton distribution

Background Plankton is the essential ecological category that occupies the lower levels of aquatic trophic networks, representing a good indicator of environmental change. However, most studies deal with distribution of single species or taxa and do not take into account the complex of biological interactions of the real world that rule the ecological processes. Results This study focused on analyzing Antarctic marine phytoplankton, mesozooplankton, and microzooplankton, examining their biological interactions and co-existences. Field data yielded 1053 biological interaction values, 762 coexistence values, and 15 zero values. Six phytoplankton assemblages and six copepod species were selected based on their abundance and ecological roles. Using 23 environmental descriptors, we modelled the distribution of taxa to accurately represent their occurrences. Sampling was conducted during the 2016–2017 Italian National Antarctic Programme (PNRA) ‘P-ROSE’ project in the East Ross Sea. Machine learning techniques were applied to the occurrence data to generate 48 predictive species distribution maps (SDMs), producing 3D maps for the entire Ross Sea area. These models quantitatively predicted the occurrences of each copepod and phytoplankton assemblage, providing crucial insights into potential variations in biotic and trophic interactions, with significant implications for the management and conservation of Antarctic marine resources. The Receiver Operating Characteristic (ROC) results indicated the highest model efficiency, for Cyanophyta (74%) among phytoplankton assemblages and Paralabidocera antarctica (83%) among copepod communities. The SDMs revealed distinct spatial heterogeneity in the Ross Sea area, with an average Relative Index of Occurrence values of 0.28 (min: 0; max: 0.65) for phytoplankton assemblages and 0.39 (min: 0; max: 0.71) for copepods. Conclusion The results of this study are essential for a science-based management for one of the world’s most pristine ecosystems and addressing potential climate-induced alterations in species interactions. Our study emphasizes the importance of considering biological interactions in planktonic studies, employing open access and machine learning for measurable and repeatable distribution modelling, and providing crucial ecological insights for informed conservation strategies in the face of environmental change