The effects of the abrupt input of high quantities of dissolved inorganic nitrogen and phosphorus on prokaryotic and eukaryotic microbial plankton were investigated in an attempt to simulate the ...nutrient disturbances caused by eutrophication and climate change. Two nutrient levels were created through the addition of different quantities of dissolved nutrients in a mesocosm experiment. During the developed blooms, compositional differences were found within bacteria and microbial eukaryotes, and communities progressed towards species of faster metabolisms. Regarding the different nutrient concentrations, different microbial species were associated with each nutrient treatment and community changes spanned from the phylum to the operational taxonomic unit (OTU) level. Network analyses revealed important differences in the biotic connections developed: more competitive relationships were established in the more intense nutrient disturbance and networks of contrasting complexity were formed around species of different ecological strategies. This work highlights that sudden disturbances in water column chemistry lead to the development of entirely different microbial food webs with distinct ecological characteristics.
•Bacterial and microbial eukaryotic communities changed after addition of high quantities of dissolved inorganic N and P.•Composition changes were obvious at the phylum level; Actinobacteria, Chlorophytes, Cryptophytes differentiated treatments.•Succession of plankton populations was similar under different nutrient conditions.•Few differentiations were found in the succession of the micro-eukaryotes: Bacillariophyta, Cilliophora and Dinoflagellata.•Different nutrient quantities caused changes in the ecological connections among OTUs.•Low nutrient addition resulted in more positive relationships between same trophic groups; high addition in negative ones.
As part of an EU funded 7th Framework project, Prevent Escape, a programme of research was undertaken to document the extent, size and knowledge of the causes of escapes from marine fin fish farms in ...Europe over a three year period. Escape incidents were identified and assessed through questionnaires across the 6 countries (Ireland, UK, Norway, Spain, Greece, and Malta), and other data supplied by the Norwegian Fisheries Directorate and the Scottish Aquaculture Research Forum. A total of 8,922,863 fish were reported to have escaped from 242 incidents. Of these over 5 million occurred in two catastrophic escape incidents. Sea bream accounted for the highest number of escapes at 76.7% followed by Atlantic salmon at 9.2%. Of the 113 Atlantic salmon escape events, almost 75% were due to structure failure or operational error. Almost 50% of cod escape incidents were due to biological causes e.g. biting of nets. The nominal costs of escapes as calculated by value at point of first sale were very substantial, estimated at approximately €47.5 million per annum on average over the study period. Of this €42.8 million was for annual cost of losses of sea bass and sea bream in the Mediterranean and €4.7 million for losses of salmon in northern Europe.
•The extent of fish farm escapes is described over a three year period across a range of offshore fish farming operations in the Atlantic and Mediterranean.•The causes of the escape events are identified and assessed.•The costs of the escape incidents to fin fish aquaculture are quantified in monetary terms for the first time.
In addition to food supply, there is a growing recognition of the wider ecosystem benefits of Integrated Multitrophic Aquaculture (IMTA) systems in coastal waters, including regulating services such ...as carbon sequestration and nutrient remediation. The water trophic status and the co-cultured species combinations affect IMTA productivity. In this study, we examined the ability of different combinations of IMTA organisms to remediate nutrients and the economic/environmental gain for reducing the environmental footprint in potential IMTA systems of the eastern Mediterranean. The results showed that the co-cultivation of organisms can reduce the negative effects on the marine environment of a fish farm both on the water column and the sediment. Meso- and eutrophic water states do not show a high variation in terms of foot print mitigation, with all three of the co-cultivated organisms to perform well. In oligotrophic waters, the obligatory absence of mussels reduces the effectiveness of the IMTA system. As expected, larger-sized IMTA systems have higher production rates and as a result higher percentage of nutrient removal. Finally, bivalve harvesting helps to remove the carbon that is trapped in their shells, contributing to the mitigation of processes related to climate change, such as the acidification of the oceans.
Integrated multitrophic aquaculture (IMTA) is an innovative mariculture methodology that reduces the environmental footprint and increases the profitability of the farm. It combines the cultivation ...of species belonging to different trophic levels, simulating a natural food web. In this study, five Mediterranean species were co-cultured in three operating fish farms in the Aegean (E. Mediterranean) Sea with different trophic conditions. The co-cultivated species were sea bream (Sparus aurata), European sea bass (Dicentrarchus labrax), Mediterranean mussel (Mytilus galloprovincialis), rayed pearl oyster (Pinctada imbricata radiata), and sea cucumber (Holothuria polii). Bream, bass, and mussels were cultivated according to the traditional on-growing methods (fish cages and longlines), whereas the pearl oysters and sea cucumbers were cultivated in baskets designed specifically for oyster farms. To estimate the growth of the co-cultivated species, growth indicators were calculated using length and weight measurements. Furthermore, the growth measurements from co-cultivated species were compared to the respective ones from natural populations. All the species showed high survival rates in the integrated multitrophic aquaculture (IMTA) conditions. Pearl oysters and Mediterranean mussels had positive growth in fish farms with high concentrations of nutrients. Mussel condition index (CI) was 42% in Aquaculture 1 (Aq1) and 33% in Aquaculture 2 (Aq2), compared to 35% in a typical Mediterranean mussel farm. Pearl oysters CI in Aq1 was 53%, in Aq2 56%, in Aquaculture 3 (Aq3) 19%, and in natural populations ranging from 30% to 45%. In contrast, holothurians did not gain weight under the fish cage regime despite the high survival rate. Their final total weight was 17.3 g in Ag1, 8.3 g in Aq2, and 18.3 g in Aq3, but in the natural population, the mean weight was 80 g.
The European Union-funded ECASA project (Ecosystem Approach for Sustainable Aquaculture) studied the impacts from aquaculture on ecosystems from northern Norway to Greece. The objectives of this ...investigation were to identify quantitative indicators of the effects of aquaculture on marine communities, and to assess their applicability over a range of ecosystems and aquaculture production systems. The study included 6 Mediterranean and 4 Atlantic sites, 7 of which produced finfish (seabream, seabass, tuna, salmon and cod), and 2 bivalve molluscs (oysters, mussels, and clams); one site produced both fish and bivalves. Cultivation methods included finfish cages, long-lines and trestles. Similar sampling methodologies were employed at the 10 study sites, obtaining sediment, hydrodynamic, and benthic faunal data. The horizontal impact from organic enrichment extended 50 m from the farms, with contradictory responses in several indicators (individual abundance, biomass) and a more consistent response of the Infaunal Trophic Index (ITI) and AZTI's Marine Biotic Index (AMBI). By means of Partial Redundancy Analysis, it was demonstrated that the environmental variables explained 53.2% of the variability in the macrofaunal variables (individual abundance, species richness, diversity, AMBI and ITI), whilst the explained variance was partialled out within three groups of variables: (i) ‘hydrography’ (depth, distance to farm, average current speed), which explained 11.5% of the variance; (ii) ‘sediment’ (Eh and percentages of silt and total organic matter), which explained 5.4%; and (iii) ‘cages’ (years of production and annual production), which explained 15.2%. The shared variance explained by interactions among these groups was 21.1%. These results, together with multiple regression analysis, provide an accurate assessment of the degree of impact from aquaculture. In conclusion, the use of several benthic indicators, in assessing farm impacts, together with the investigation of dynamics of the studied location, water depth, years of farm activity, and total annual production, must be included when interpreting the response of benthic communities to organic enrichment from aquaculture.
A large data set from the Eastern Mediterranean was analyzed to explore the relationship between seawater column variables and benthic community status. Our results showed a strong quantitative link ...between the seawater column variables (Chlorophyll a and Eutrophication Index) and various indicators describing benthic diversity and community composition. The percentage of benthic opportunistic species increased significantly in the stations with high trophic status of the seawater column and so did the strength of the coupling between values of seawater column and benthic indicators. The Eutrophication Index threshold level of 0.85, separating the "Bad and Poor" from "Moderate to High" conditions could serve as an acceptable critical value above which there is a readily observable change in benthic community composition.
Smaller sized plastics (microplastics or MPs <5 mm) are ubiquitous in nature and have been found to interact in diverse ways with most biotic and abiotic systems globally. Most MPs in the seas have a ...land-based source, however, little is known about how the transfer occurs. In our study, we used three sandy beaches to describe the process of how MPs travel from accumulation points at the backshore of the beach to the sea, and vice versa. MPs differed significantly in all three beaches (both in quantitative and qualitative terms) between the summer and the winter samplings. During the summer, heavy MPs are the majority, while during the winter, lightweight microplastics are predominant, and the ratio of heavy per lightweight MPs is affected by the sediment median diameter after the summer sampling. Macroplastics follow a similar pattern to MPs and appear to provide a source of MPs for the sea.
•Seasonal variability in macro and micro pollution in an on beach sediment•Plastic pollution differentiates with beach use and proximity to urban centers.•Granulometry, weather conditions, seasonality affect plastic pollution.•Management options should be chosen based on the origin of pollution on a beach.
Τhis study aims to measure the abundance of microplastic (MP) particles in the soft tissue of mussel (Mytilus galloprovincialis) and pearl oyster (Pinctada imbricata radiata) specimens. Samples were ...collected at four sites in Greece (Sagiada, Malesina, Elounda, Rhodes) from wild and farmed populations. The identification of MPs was accomplished by Raman spectroscopy. Comparisons were made between the two different species where the two species co-existed (Malesina), between the four study sites (five sampling stations) in relation to P. imbricata radiata individuals, and also in every station for the different MP types found. For the specimens from Malesina, M. galloprovincialis had more MPs in their soft tissue compared to P. imbricata radiata. Microfibers were found in abundance in M. galloprovincialis, while microfragments were found in P. imbricata radiata specimens. The main MP type found in P. imbricata radiata specimens was microfragments in all five sampling stations, and ranged between 1.54 ± 0.63 (Rhodes-baskets) and 3.56 ± 0.35 (Sagiada) MP particles/g. While the samples of mussels and pearl oysters were similar in age, the differences found in the concentrations of MPs appears to be due to their different farming methods and location characteristics concerning the five sampling stations of pearl oysters. This study indicates that the culturing system does not affect MP concentration in bivalves, and further investigation is needed to find the most appropriate method to limit and reduce MPs that end up in the farmed organisms.
The diversity and distribution of polychaetes in the coastal area and the EEZ of the Republic of Cyprus is presented based on both the literature records and new data acquired in a wide range of ...environmental monitoring programmes and research projects. A total of 585 polychaete species belonging to 49 families were reported in Cyprus waters; among them, 205 species (34%) were recorded based on the literature only, 149 (26%) were new records based on our own data, and a total of 231 spp. (40%) were recorded from both the literature and new data. A total of 51 polychaete species were identified as non-indigenous; among them, 32 were confirmed as alien species, 4 were considered cryptogenic, and 15 were considered questionable as there were doubts about their identity. The Indo-Pacific Schistomeringos loveni was reported for the first time in the Mediterranean Sea, while four species already reported in the literature, namely, Bispira melanostigma, Fimbriosthenelais longipinnis Leonnates aylaoberi, and Rhodopsis pusilla, were added to the list of non-indigenous polychaetes in the Mediterranean Sea. The current work highlights the importance of implementing environmental monitoring programmes and carrying out research surveys targeting benthic macrofauna assemblages.
Microplastics are small plastic particles (<5 mm) that are found in most marine habitats around the world. Currently, several studies are trying to determine their exact effects. Microplastics can be ...introduced into the marine ecosystem directly as manufactured microplastics, or indirectly through the decomposition of larger plastic particles. They can enter the food chain, and can be found as vectors for the movement of microbial communities and chemical pollutants. In our study, two different ways of measuring microplastics were tested at three Mediterranean beaches, each subject to different types of human pressure. The purpose of the study was to compare different sampling approaches for assessing the microplastics present in sediment, taking into account temporal variability across the summer and winter seasons. Statistically significant differences were found between the beaches, which reflect the distinct uses made of each of them. At the same time, significant differences were found in the contents of microplastics, which were due to seasonal variability. Our analysis showed that microplastics can be found in deeper sediment layers with different concentrations to that of the surface layer. Therefore sampling methods that do not sample the same sediment layer do not seem to produce comparable results. In addition, classic categorizations of microplastics (as microfibers, membranes, etc.) may not always be sufficient. Rather, a classification based on microplastic properties, the specificities of each region and each study's objectives is recommended.
•Two sampling approaches of collecting microplastics from sediments were compared in three sandy beaches and two time periods.•The two methods applied were (a) sampling using a core (depth sampling) and (b) surface sampling.•Microplastics were identified by optical stereoscope and FT-IR microscope.•We found quantitative and qualitative differences in the microplastics between the two sampling methods.•Categorization of microplastics based on their properties, specificities of each region and study objectives should be used.
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