Environmental variability and heavy metal concentrations from five lagoons in the Ionian Sea (Amvrakikos Gulf, W Greece)

Background: Coastal lagoons are ecosystems of major importance as they host a number of species tolerant to disturbances and they are highly productive. Therefore, these ecosystems should be protected to ensure stability and resilience. The lagoons of Amvrakikos Gulf form one of the most important lagoonal complexes in Greece. The optimal ecological status of these lagoons is crucial for the well-being of the biodiversity and the economic prosperity of the local communities. Thus, monitoring of the area is necessary to detect possible sources of disturbance and restore stability. New information: The environmental variables and heavy metals concentrations, from five lagoons of Amvrakikos Gulf were measured from seasonal samplings and compared to the findings of previous studies in the area, in order to check for possible sources of disturbance. The analysis, showed that i) the values of the abiotic parameters vary with time (season), space (lagoon) and with space over time; ii) the variability of the environmental factors and enrichment in certain elements is naturally induced and no source of contamination is detected in the lagoons

Polytraits : a database on biological traits of marine polychaetes

The study of ecosystem functioning – the role which organisms play in an ecosystem – is becoming increasingly important in marine ecological research. The functional structure of a community can be represented by a set of functional traits assigned to behavioural, reproductive and morphological characteristics. The collection of these traits from the literature is however a laborious and time-consuming process, and gaps of knowledge and restricted availability of literature are a common problem. Trait data are not yet readily being shared by research communities, and even if they are, a lack of trait data repositories and standards for data formats leads to the publication of trait information in forms which cannot be processed by computers. This paper describes Polytraits (http://polytraits.lifewatchgreece.eu), a database on biological traits of marine polychaetes (bristle worms, Polychaeta: Annelida). At present, the database contains almost 20,000 records on morphological, behavioural and reproductive characteristics of more than 1,000 marine polychaete species, all referenced by literature sources. All data can be freely accessed through the project website in different ways and formats, both human-readable and machine-readable, and have been submitted to the Encyclopedia of Life for archival and integration with trait information from other sources

A pan-European valuation of the extent, causes and cost of escape events from sea cage fish farming

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.peer-reviewe

The potential impact of Saharan dust and polluted aerosols on microbial populations in the East Mediterranean Sea, an overview of a mesocosm experimental approach.

Recent estimates of nutrient budgets for the Eastern Mediterranean Sea (EMS) indicate that atmospheric aerosols play a significant role as suppliers of macro- and micro- nutrients to its Low Nutrient Low Chlorophyll water. Here we present the first mesocosm experimental study that examines the overall response of the oligotrophic EMS surface mixed layer (Cretan Sea, May 2012) to two different types of natural aerosol additions, “pure” Saharan dust (SD, 1.6 mg l-1) and mixed aerosols (A - polluted and desert origin, 1 mg l-1). We describe the rationale, the experimental set-up, the chemical characteristics of the ambient water and aerosols and the relative maximal biological impacts that resulted from the added aerosols. The two treatments, run in triplicates (3 m3 each), were compared to control-unamended runs. Leaching of approximately 2.1-2.8 and 2.2-3.7 nmol PO4 and 20-26 and 53-55 nmol NOx was measured per each milligram of SD and A, respectively, representing an addition of approximately 30% of the ambient phosphate concentrations. The nitrate/phosphate ratios added in the A treatment were twice than those added in the SD treatment. Both types of dry aerosols triggered a positive change (25-600% normalized per 1 mg l-1 addition) in most of the rate and state variables that were measured: bacterial abundance (BA), bacterial production (BP), Synechococcus (Syn) abundance, chlorophyll-a (chl-a), primary production (PP) and dinitrogen fixation (N2-fix), with relative changes among them following the sequence BP>PP≈N2-fix>chl-a≈BA≈Syn. Our results show that the ‘polluted’ aerosols triggered a relatively larger biological change compared to the SD amendments (per a similar amount of mass addition), especially regarding BP and PP. We speculate that despite the co-limitation of P and N in the EMS, the additional N released by the A treatment may have triggered the relatively larger response in most of the rate and state variables as compared to SD. An implication of our study is that a warmer atmosphere in the future may increase dust emissions and influence the intensity and length of the already well stratified water column in the EMS and hence the impact of the aerosols as a significant external source of new nutrients

Impact of aquaculture to the benthic macrofauna and the ecosystem functions

The habitat inhabited by and in turn modified by the benthos is the result of many interacting factors, of regimes which cover scales from the global to the local, and of the intimate linkages between the water column and its factors and the substratum and its factors. Human impacts have major effects in the coastal benthic systems. In the case of Mediterranean fish farms it seems that they often are settled in the important habitat of Posidonia oceanica fields because the environmental characteristics of these areas (strong currents, good water quality, coarse sediment) fit perfectly with the special requirements of the fish farms. To study the impact of fish farming in different benthic Mediterranean habitats it was examined the pattern of organically enriched sediments by fish farming activities in a gradient of different sediment types. As testing grounds, muddy and seagrass habitats were chosen because of the different biogeochemical characteristics and functions of these areas. Our results showed the relationship of the biogeochemical variables with bathymetry and sediment composition. Although the spatial extent of the organic enrichment due to fish farming was the same, faunal organisms and geochemical variables showed different patterns according to the functions of their habitat. The sediment fluxes of nutrients and oxygen were used as proxies for the study of the relationship between macrobenthic diversity and ecosystem function in the gradients of organically enriched sediments. The relationship between benthic diversity and TOC concentration followed the pattern proposed by (Hyland et al. 2005). Our results showed that fauna, abiotic factors, oxygen fluxes and nutrient exchange determined the function of the benthic ecosystem. The shifts in biogeochemical processes occurred as a function of diversity and depended on the nature of the sediments. In order to remove the effect of sediment functioning variability, we repeated the analyses separately for the two major habitat types (bare sediment of muddy and seagrass habitats). It seems that the overall response of biological and geochemical variables to the organic enrichment varied considerably among habitat types and the effects on the benthic environment are more difficult to detect in coarse sediments through standard monitoring.Τα θαλάσσια ιζήματα κατοικούνται και μεταβάλλονται από τους βενθικούς οργανισμούς δημιουργώντας μια σειρά παραμέτρων που αλληλεπιδρούν, ενώ τα συστήματά που δημιουργούν μπορεί να καλύπτουν από τοπικής μέχρι παγκόσμιας κλίμακας διεργασίες. Οι ανθρωπογενείς επιδράσεις επηρεάζουν τα παράκτια βενθικά συστήματα. Ιδιαίτερα στην περίπτωση των ιχθυοκαλλιεργειών φαίνεται ότι συχνά εγκαθίστανται πάνω από τα σημαντικά ενδιαιτήματα των λειμώνων Posidonia oceanica επειδή τα ιδιαίτερα περιβαλλοντικά χαρακτηριστικά των περιοχών αυτών (ισχυρά ρεύματα, καλή ποιότητα νερού και αδρά ιζήματα) ταιριάζουν απόλυτα με τις απαιτήσεις των ιχθυοτροφείων. Για την μελέτη της επίδρασης των ιχθυοκαλλιεργειών σε διαφορετικά ενδιαιτήματα και ιζήματα της Μεσογείου ερευνήθηκαν οι διαφορές στο πρότυπο μεταβολής διαφορετικών τύπων ιζήματος σε ιζήματα οργανικά εμπλουτισμένα από ιχθυοκαλλιεργητικές δραστηριότητες. Ως περιοχές ελέγχου επιλέχθηκαν ιζήματα από λασπώδη και αμμώδη ενδιαιτήματα (σε γειτνίαση με λειμώνες φανερόγαμων), λόγω των διαφοροποιημένων βιογεωχημικών χαρακτηριστικών και λειτουργιών που παρουσιάζουν. Τα αποτελέσματα της παρούσας εργασίας έδειξαν την σχέση των βιογεωχημικών μεταβλητών με την βαθυμετρία και την σύσταση του ιζήματος. Ως εκφραστές της σχέσης της μακροβενθικής ποικιλότητας και της οικοσυστημικής λειτουργίας χρησιμοποιήθηκαν οι ροές των θρεπτικών και του οξυγόνου στην διαχωριστική επιφάνεια νερού ιζήματος. Η σχέση μεταξύ της ποικιλότητας των οργανισμών και της συγκέντρωσης του ολικού οργανικού άνθρακα ακολούθησε το πρότυπο που πρότειναν οι Hyland et al. (2005). Από τα αποτελέσματα φάνηκε ότι η πανίδα, οι αβιοτικοί παράγοντες και η ανταλλαγή του οξυγόνου και των θρεπτικών καθόρισαν την λειτουργία του βενθικού οικοσυστήματος. Οι μεταβολές στις βιογεωχημικές διεργασίες εμφανίστηκαν ως συνάρτηση της ποικιλότητας αλλά φάνηκε ότι εξαρτώνται και από την φύση των ιζημάτων. Παρά το ότι η χωρική έκταση του οργανικού εμπλουτισμού ήταν η ίδια οι βενθικοί οργανισμοί και οι γεωχημικές μεταβλητές των εξεταζόμενων ενδιαιτημάτων έδειξαν διαφορετικά πρότυπα ανάλογα με τις λειτουργίες τους. Για την αφαίρεση της επίδρασης λειτουργικής ποικιλότητας των ιζημάτων οι αναλύσεις επαναλήφθηκαν χωριστά για τους δύο κύριους τύπους ενδιαιτημάτων του γυμνού ιζήματος (λασπώδες και λειμώνων φανερόγαμων). Φαίνεται ότι η γενική απόκριση των βιολογικών και γεωχημικών παραμέτρων στον οργανικό εμπλουτισμό διαφοροποιήθηκε σημαντικά ανάμεσα στα διαφορετικά ενδιαιτήματα. Επίσης οι επιδράσεις στο βενθικό περιβάλλον των αδρών ιζημάτων είναι πιο δύσκολα ανιχνεύσιμες με τις συνήθεις μεθόδους παρακολούθησης

Response of Benthic Macrofauna to Eutrophication in a Mesocosm Experiment: Ecosystem Resilience Prevents Hypoxic Conditions

A benthic-pelagic mesocosm experiment was performed to study how the benthic macrofaunal community responds to a eutrophication gradient. The novel experimental setup allowed the induction of an eutrophication gradient in the water column and the detailed documentation of the response of the benthos in terms of biodiversity and ecosystem processes. Nine mesocosms were deployed in the facilities of the Hellenic Center for Marine Research in Crete in the eastern Mediterranean. The mesocosms were 4 m deep, contained 1.5 m3 coastal water, and included 85 liters of undisturbed sediment at the bottom. No water or sediment exchange was allowed. The experimental design included a Control and two eutrophication levels (Low and High) for the 58-day duration of the experiment. Macrofaunal samples were collected at the end of the experiment from each mesocosm and compared to the ones collected at the beginning of the experiment from the sediment collection area. Results show that the High eutrophication treatment differed significantly from the Control and Low treatments in terms of macrofaunal species composition, diversity, ecological status and ecosystem processes. The increased availability of organic matter in the sediment caused differences in macrofaunal community structure by favoring deposit-feeding species with high bioturbation ability, which significantly increased their abundance. The increased bioturbation potential of the new community combined with the high organic matter consumption contributed to the oxygenation of the sediment within the mesocosm, preventing the creation of hypoxic conditions in the sediment and maintaining ecosystem health despite the highly eutrophic conditions and significant changes in sediment geochemical variables. In the oligotrophic eastern Mediterranean, healthy benthic ecosystems may use existing ecosystem processes to “buffer” the negative effects caused by eutrophication

Ο κύκλος του αζώτου σε τεχνητούς υγροβιότοπους και η επίδραση της βλάστησης σε αυτόν

Μεταπτυχιακή διατριβή στα πλαίσια του Προγράμματος Μεταπτυχιακών Σπουδών "Περιβαλλοντική και Υγειονομική Μηχανική"Περίληψη: Στην παρούσα Μεταπτυχιακή Διατριβή διερευνήθηκε ο κύκλος του Αζώτου (Ν) κατά την εφαρμογή Υγρών Αποβλήτων (ΥΑ) σε Τεχνητούς Υγροβιοτόπους Οριζόντιας Επιφανειακής Ροής (FWS). Για την επίτευξη του στόχου αυτού κατασκευάστηκαν στο Πολυτεχνείο Κρήτης έξι πιλοτικές μονάδες, δύο χωρίς βλάστηση, δύο φυτεμένοι με Typha Latifolia και δύο με Arundo Donax. Το πείραμα έλαβε χώρα κάτω από ελεγχόμενες συνθήκες, χρησιμοποιήθηκε συνθετικό ΥΑ και πραγματοποιήθηκαν συχνές δειγματοληψίες. Τα αποτελέσματα έδειξαν ισχυρή επίδραση της παρουσίας βλάστησης καθώς και του φυτικού είδους στην απομάκρυνση της ΝΗ4-Ν, των ΑΑ και του ΤΚΝ. Επιπλέον, παρατηρήθηκε γενικότερα μία καλύτερη αντιμετώπιση στα συστήματα που ήταν φυτεμένα με T. Latifolia συγκριτικά με αυτά με A. Donax, η οποία παρατηρείται πιο ειδικά, τόσο στα ΑΑ, στην ΝΗ4-Ν όσο και στο ΤΚΝ. Οι ρυθμοί απομάκρυνσης της ΝΗ4-Ν ήταν αρνητικοί, και κυμάνθηκαν από -62 mg/m2/d (για ΤΥ που δεν έφεραν βλάστηση) έως -10 mg/m2/d (για τα συστήματα που ήταν φυτεμένα με T. Latifolia. Τα αποτελέσματα φανερώνουν παρεμπόδιση της νιτροποίησης, πιθανώς λόγο του ανοξικού περιβάλλοντος και του μικρού χρόνου παραμονής του αποβλήτου στα συστήματα. Η κύρια διεργασία απομάκρυνσης Ν στα υπό εξέταση συστήματα, φυτεμένα με T. Latifolia, φαίνεται να είναι η απονιτροποίηση (με ρυθμούς απομάκρυνσης έως 61.95 mg/m2/d), ενώ για τα υπόλοιπα συστήματα δεν εμφανίζεται κύρια διεργασία απομάκρυνσης Ν. Η διεργασία ΑΝΑΜΜΟΧ χρήζει περεταίρω έρευνα και παρακολούθηση με εξειδικευμένες μεθόδους (FISH, qPCR, ισότοπα Ν). Τέλος, όλα τα παραπάνω, αναδεικνύουν την ανάγκη περαιτέρω έρευνας πάνω στη διερεύνηση του κύκλου του Ν στους TY, στην ποσοτικοποίηση της συνεισφοράς των ΑΝΑΜΜΟΧ σε αυτόν, καθώς και στην βελτιστοποίηση του σχεδιασμού ΤΥ ως προς την απόδοση απομάκρυνσης Ν.Summarization: Main goal of the present study was the investigation of the N circle along with the contribution of vegetation on CW. For this purpose, six pilot FWCWs were built in Technical University of Crete, 2 without vegetation, 2 with Typha Latifolia and 2 with Arundo Donax. The experiment took place under controlled conditions with often samplings and the use of synthetic sewage. Results showed that there are significant differences between the wetlands that were planted and those who weren’t regarding the removal of NH4-N, AA and TKN. Additionally, there was observed a generally better confrontation in the systems that were planted with T. Latifolia compared to those planted with A. Donax, which is observed more specific in the AA, NH4-N and TKN. NH4-N removal rates were negative, and ranged between -62 mg/m2/d (for the unplanted systems) to -10 mg/m2/d (for systems planted with T. Latifolia). The results reveal inhibition of nitrification, probably because of the anoxic environment and the small retention time in the systems. The main N removal procedure in the examined CWs planted with T. Latifoliaseems to be denitrification (with removal rates up to 61.95 mg/m2/d), while for the rest CWs there doesn’t seem to be a main N removal process. ANAMMOX procedure erquires further research along with specialized methods (FISH, qPCR, N isotopes) . Summarizing, all above show the need for further research on the N cycle in the CWs, on the quantification of the ANAMMOX contribution and on optimizing the design of the CWs regarding N removal efficiency

An IMTA in Greece: Co-Culture of Fish, Bivalves, and Holothurians

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