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Lack of detailed knowledge on ecological niche, life cycles, spatial distribution, reproductive biology and space use strongly affects the selection of useful tools and measures in the conservation of threatened marine species. Especially for sedentary and slow species, behaviour and movement capacities are supposed to be the most important functional traits. Indeed, behavioural variability concerning available space and the close presence of individuals is considered a crucial trait for the population dynamics assessments, especially when disturbances of various causes are present in the environment. The present study aimed to investigate the site fidelity and degree of movement of Hippocampus guttulatus, an emblematic and threatened Mediterranean seahorse species. With this aim, a number of seahorses were tagged and monitored throughout two years within a limited area of the lagoon of Mar Piccolo of Taranto (Southern Italy). The studied individuals were initially morphometrically measured for size, sex and life-cycle stage and subsequently monitored through repeated four-month surveys each year. Obtained results indicated high site fidelity regardless of habitat type. Movement pattern was in line with the data on congeneric species, although values were slightly higher. The analyses showed differences in movement degree among different sexes and life-cycle stages and indicated greater mobility of adult females compared to males and juveniles. The investigated parameters showed a great variability suggesting that even small-scale environmental factors can influence the species mobility. Finally, a change in the population structure has been observed, with the loss of large individuals in 2016 and reduced recruitment in 2017. These findings indicated the possible presence of stressors that could lead to the alteration of the seahorse population at Mar Piccolo of Taranto.

The potential of rice protein concentrate (RPC) to substitute fishmeal (FM) protein in the diet of Oreochromis niloticus was assessed in a five-month-long feeding trial. Fishmeal protein was replaced by RPC at rates of 0% (control), 25%, 50%, and 75% (RPC0, RPC25, RPC50, and RPC75, respectively). RPC25 had no significant effect on antioxidant capacity (total antioxidant capacity; superoxide dismutase, catalase, and glutathione peroxidase activities) and immune indices (lysozyme, nitric oxide, antiprotease, and bactericidal activities) after one, two, and five months of feeding, while the values for these parameters were significantly lower in the RPC75 group compared to those in the RPC0 group. The RPC25 group showed higher mRNA levels of the intestinal cytokines IL-1β, IL-10β, TGF-β, and TNF-α than the control group. In fish affected by Aeromonas veronii, the highest significant cumulative mortality was recorded in the RPC75 group, followed by the RPC50, RPC25, and control groups. Gut microbiome analyses showed a reduction in microbial diversity in response to the addition of RPC, regardless of the RPC content, and the composition of the community of the RPC samples differed from that of the control. RPC-enriched diets resulted in higher relative abundances of Bacteroidetes and Fusobacteria in the gut compared to that in the gut of the control fish. In summary, RPC can be used to replace up to 25% of the FM protein in the diet of O. niloticus, while improving the antioxidant capacity, immunocompetence, and disease resistance of the fish.

Understanding the spread and establishment of non-indigenous species (NIS) is one of the primary areas of focus in bioinvasion science and is essential for generating appropriate management strategies in aquaculture. Here we investigated the role of 2 non-indigenous serpulid tube worms (Hydroides elegans and H. dirampha) in shaping the hard substrata communities around a fish farm in the Strait of Sicily over 1 yr (June 2014-June 2015), at 3 mo intervals (September and December 2014, March and June 2015). The mean density values of serpulids were significantly different at each sampling time. The density of serpulids on submerged panels showed a peak in spring (March 2015, after 9 mo) and decreased drastically in summer (June 2015). Hydroides shaped the entire associated macrobenthic community, which showed the highest density in the first month of observations. The lowest density was recorded in proximity to the highest density of serpulids. Margalef’s species richness of the associated macrofaunal community peaked at the end of monitoring (summer). Our results will add new insights into the role of aquaculture as a vector and pathway for NIS.

The concentration of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn were analyzed in the edible part of several species of fish, crustaceans, molluscs and echinoderms collected in sensitive areas of the Tuscany coast (northern Italy). The concentration of As (0.39–78.1 μg g−1) and Hg (0.01–1.56 μg g−1) resulted in most cases higher than reference thresholds. Target hazard quotient (THQ) and lifetime cancer risk (TR) indexes were calculated to assess cancer and non-cancer risk due to oral exposure; the highest THQ values referred to As and Hg, with values ≥ 1 in 39% and 48% of cases, respectively. Total target hazard quotients (TTHQ) values suggested that the local population could experience adverse health effects due to consumption of local seafood, mainly of demersal and benthic species. Cancer risk was mainly associated with As exposure, and with Cd intake, especially through molluscs consumption. The NMDS model highlighted species specific bioaccumulation processes and specific sensitivity of species to different bioavailable heavy metals. Specifically, Mullus spp. and Scorpaena porcus preferentially accumulate Hg and Cr, Octopus vulgaris specimens were discriminated by the presence of Pb and Zn, while an evident preference for Cd and Cu was recorded in Squilla mantis. In addition, the distribution of heavy metals in organisms revealed sound differences between Follonica and Livorno sampling sites, demonstrating a highly heterogeneous anthropogenic impact in terms of heavy metals input from the industrial activity resting on land.

13 pages, 3 tables, 5 figures, The COVID-19 global pandemic has had severe, unpredictable and synchronous impacts on all levels of perishable food supply chains (PFSC), across multiple sectors and spatial scales. Aquaculture plays a vital and rapidly expanding role in food security, in some cases overtaking wild caught fisheries in the production of high-quality animal protein in this PFSC. We performed a rapid global assessment to evaluate the effects of the COVID-19 pandemic and related emerging control measures on the aquaculture supply chain. Socio-economic effects of the pandemic were analysed by surveying the perceptions of stakeholders, who were asked to describe potential supply-side disruption, vulnerabilities and resilience patterns along the production pipeline with four main supply chain components: a) hatchery, b) production/processing, c) distribution/logistics and d) market. We also assessed different farming strategies, comparing land- vs. sea-based systems; extensive vs. intensive methods; and with and without integrated multi-trophic aquaculture, IMTA. In addition to evaluating levels and sources of economic distress, interviewees were asked to identify mitigation solutions adopted at local / internal (i.e., farm-site) scales, and to express their preference on national / external scale mitigation measures among a set of a priori options. Survey responses identified the potential causes of disruption, ripple effects, sources of food insecurity, and socio-economic conflicts. They also pointed to various levels of mitigation strategies. The collated evidence represents a first baseline useful to address future disaster-driven responses, to reinforce the resilience of the sector and to facilitate the design reconstruction plans and mitigation measures, such as financial aid strategies, M.C.M.'s research activity was supported by the European Union's Horizon 2020 Research and Innovation programme under the Marie Skłodowska-Curie Action (Grant agreement no. 835589, MIRROR Project). People at the Laboratory of Ecology have been funded by the PRIN-MAHRES project (Ministry of Italian Research; MUR - 017MHHWBN_003 Linea C) and by the Interreg Italia-Malta HARMONY 2016 (Grant C1-3.1-31). C. Pita and A. Nogueira would like to thank FCT/MCTES for the financial support to CESAM (UIDP/50017/2020+UIDB/50017/2020), through national funds. J.M.F. Babarro thanks project PID2019-106008RB-C21 for support through Spanish Government funds. The authors would like to thank also the ERASMUS+-FISHAQU project (No. 610071-EPP-1-2019-1-PT-EPPKA2-CBHE-JP)

Understanding the multifaceted nature of environmental fluctuations is crucial to predicting the physiological adjustments utilised by organisms in resisting or adapting to changes over time. Here we investigate the effects of 2 environmental stressors on tunicates, whose fitness can have important repercussions on the quality of habitat. Specifically, we report respiration rate (RR), clearance rate (CR), and assimilation efficiency (AE) of the ascidian Styela plicata in response to a range of temperatures and varying food availability. Temperature-dependent RR was observed only within a portion of the thermal window of the species. Significant differences in clearance rates were detected among organisms fed with varying algal concentrations, while no significant influence of food concentrations on AE was observed. This plasticity of the physiological rates and the development of ubiquitous mechanisms such as temperature-insensitive aerobic metabolism suggest a competitive advantage of this group. Such knowledge may allow for more accurate predictions of the physiological and evolutionary mechanisms driving current and future distribution of this species.

The integrated multi-trophic aquaculture (i.e., IMTA) is a practice combining organisms with different trophic levels with the final purpose of transforming the continuous waste of food by targeting species into nutrient input for other non-target species. This practice very often involves filter feeders, such as bivalves, by the use of which bioenergetics budgets are strongly influenced by the quality and quantity of different foods. However, to date, scant information is available, to really understand the rebounds of food availability on the growth performances of these harvested biomasses in the natural environment. By choosing the mussel Mytilus galloprovincialis as a model, this study aims to (1) characterize the functional response of the species to define all parameters related to food intake strategies and (2) to investigate how responses change as a function of varying food sources. Laboratory procedures have been designed to evaluate the clearance rates (CR) and assimilation efficiencies (AE) of M. galloprovincialis with varying food concentrations, while different diets (i.e., seagrass, phytoplankton, and pellets) have been provided to investigate how differently they reach saturation. Results show that in the presence of phytoplankton and seagrass as food sources, the feeding strategies of M. galloprovincialis follow a II-type Holling's curve, while it shows a I-type Holling's curve when pellet food is provided. Investigating the behavioural components of functional responses may improve our ability to predict where to place shellfish cultures, as it may be useful in the context of IMTA management and in addressing siting studies. Statement of relevance Our paper focuses on a question central to understanding and predicting the likely impacts of one among the most important human economic activity like the aquaculture in coastal habitats. The main question deals with the possibility to combine experimental procedures with the new mechanistic functional trait based bioenergetic models in order to effectively predict life history traits of cultivated species.

The capture of large amounts of small, immature fish of commercial species is a serious problem particularly in multispecies fisheries. Moreover, considerable and increasing interest is being devoted by fishery scientists to identify the distribution and habitat needs of species throughout their life cycle. To elucidate species composition, the abundance of juveniles in the demersal assemblages and the role of different life history (juvenile and adult) stages of target species in structuring demersal communities, two bottom trawl surveys were carried out during the autumn 2003 and 2004. Multivariate analyses were performed on density indices of adults and juveniles life stages of 30 target species and total density indices for the remainder of the catch species. Juveniles represent more than 61% of the total catch in both the years investigated and their abundance and spatial distribution was strictly related to the sea bottom biocoenotic features. Most juveniles were concentrated in the coastal shelf area and in particular in the hauls performed on the Coastal Terrigenous Mud biocoenosis (CTM). The demersal assemblages located in the slope stratum showed, in general, a lower concentration of juvenile specimens; however, some facies of the Bathyal Mud biocoenosis that characterizes the deep layer of our study area showed a very high percentage of juveniles. This information improves our understanding of ecosystem functioning and represents a useful basis for providing advice on the management of multispecies demersal fisheries within an ecosystem approach. © 2013 Elsevier Ltd.

The behavioural deficit of hatchery reared (HR) fish used for stock enhancement is the main cause of their low survival in the wild. In this study the effects of predator and shelter conditioning on survival and dispersal of HR white seabream ( Diplodus sargus ) released at sea were investigated. The hypotheses were that conditioned white seabream would avoid predators more efficiently and would be more capable to shelter, showing higher survival and smaller dispersal than naive fish. Six thousand HR white seabream (6.32 ± 0.93 cm total length) were allocated in twelve plastic tanks and divided in four experimental groups: three groups were conditioned with a predator, a refuge or both, while one group was left unconditioned and used as a control. The conditioning phase lasted 30 days and was conducted using live conger eels as predators and pyramids of perforated bricks as refuges. Flight initiation distance (FID) and time to shelter (TS) were used as response variables to test the effects of conditioning in the arena, using a dummy conger eel. The effect of conditioning on post-release survival and dispersal was assessed through the monitoring of 1465 tagged seabream belonging to the four experimental groups, released at sea. Underwater visual census was used as monitoring technique. The sighting rate (SR) (sighted fish / released fish × 100) and the distance ( D ) of each sighted fish from the release site were used as proxies for post-release survival and dispersion, respectively. In the arena, conditioned seabream showed significantly higher FID and lower TS than naive fish. At sea, the estimated post-release survival of conditioned seabreams (SR = 9.4%) was almost twice as much as that of naive individuals (SR = 5.5%). The dispersal of HR seabream acclimated to refuges from the release site ( D = 2.4 ± 3.1 km) resulted lower than in naive fish ( D = 3.7 ± 4 km). This study indicates that predator and shelter conditioning of HR white seabream is an effective practise to increase their post-release survival at sea, and our findings provide support for effective stock enhancement initiatives.

Background: The global decline of marine biodiversity and the perceived need to protect marine ecosystems from irreparable alterations to ecosystem functioning and ecosystem service provision have produced an extensive range of spatial management measures (SMMs). The design of SMMs is a complex process often involving the integration of both conservation objectives and socio-economic priorities and the resultant trade-offs are highly dependent on the management regime in place. Future marine management is likely to involve greater use of different forms of protected areas with differing levels of protection, particularly for sites where there are multiple competing demands. Consequently, evaluations of the characteristics that enable different forms of SMMs to successfully achieve their objectives are required to inform future conservation networks. The objective of this evidence-based analysis is to assess and compare the biological effects of different forms of SMMs with the aim of providing additional guidelines and insight into the design of future SMMs. Methods: SMMs will be grouped into four main categories according to the degree of management enforcement (marine reserve, marine protected area, partial permanent protection, partial temporal protection). To identify and collate evidence to address these questions a comprehensive systematic search of peer-reviewed scientific literature and grey literature will be undertaken. Articles will be examined for relevance using specified inclusion criteria and the included papers will be critically appraised. Studies that examine the effects on an outcome comparing at least one spatial management measure vs no protection (open access area) or between interventions will be considered. Subgroup analyses and meta-regression will be performed to explore variation in biological effects in relation to covariates (SMMs parameters, habitat and species functional and biological traits).

Ocean acidification is the suite of chemical changes to the carbonate system of seawater as a consequence of anthropogenic carbon dioxide (CO2) emissions. Despite a growing body of evidences demonstrating the negative effects of ocean acidification on marine species, the consequences at the ecosystem level are still unclear. One factor limiting our ability to upscale from species to ecosystem is the poor mechanistic understanding of the functional consequences of the observed effects on organisms. This is particularly true in the context of species interactions. The aim of this work was to investigate the functional consequence of the exposure of a prey (the mussel Brachidontes pharaonis) to ocean acidification for both the prey and its predator (the crab Eriphia verrucosa). Mussels exposed to pH 7.5 for >4 weeks showed significant decreases in condition index and in mechanical properties (65% decrease in maximum breaking load) as compared with mussels acclimated to pH 8.0. This translated into negative consequences for the mussel in presence of the predator crab. The crab feeding efficiency increased through a significant 27% decrease in prey handling time when offered mussels acclimated to the lowest pH. The predator was also negatively impacted by the acclimation of the prey, probably as a consequence of a decreased food quality. When fed with prey acclimated under decreased pH for 3 months, crab assimilation efficiency significantly decreased by 30% and its growth rate was 5 times slower as compared with crab fed with mussels acclimated under high pH. Our results highlight the important to consider physiological endpoints in the context of species interactions.

Submersible sea-cages represent an alternative method to standard surface-based cages, and could help solve several production problems that exist in surface-based farming, such as heavy storms, algal and jellyfish blooms and attacks by predators. In this study, we investigated growth, haematological, biochemical and immunological parameters of European sea bass ( Dicentrarchus labrax ) farmed in surface and submersible cages, to compare the physiological status under different rearing conditions. In addition, we evaluated the use of erythrocyte HSP70 levels as a biomarker of fish welfare. The study was conducted in two submerged and two surface cages filled with D. labrax . No significant differences were observed in the growth rate and the relative condition factor between the two groups. Significantly higher levels of serum cortisol, haematocrit plasma glucose and total plasma proteins were measured in surface-based cages. Conversely, fish in submerged cages showed higher haemolytic activity and lysozyme levels in both mucus and kidney than surface reared sea bass. Results obtained in this study indicate that submergence could be a favorable condition for sea bass farming, suggesting mariculture in submerged net cages as a promising system that allows producers to minimize stress (included that from predation by fish-eating birds) and therefore favor animal welfare.

Conventional sectoral management and piecemeal governance are considered less and less appropriate in pursuit of sustainable development. Ecosystem based marine spatial management (EB-MSM) is an approach that recognizes the full array of interactions within an ecosystem, including human uses, rather than considering single issues, species, or ecosystem services in isolation. Marine spatial planning and ocean zoning are emerging concepts that can support EB-MSM. EB-MSM is driven by high-level goals that managers aim to achieve through the implementation of measures. High-level goals and objectives need to be translated into more operational objectives before specific targets, limits and measures can be elaborated. Monitoring, evaluation and adaptation are necessary to ensure that marine management measures are both effective and efficient. Solid monitoring frameworks are the foundation of adaptive management, as they provide the necessary information to evaluate performance and the effectiveness of management actions. Marine protected areas (MPAs) - possibly set up in networks - constitute a key component in EB-MSM policies and practises and have been applied as a cornerstone in conservation of marine biodiversity, management of fish populations, development of coastal tourism, etc. Moreover, MPA experiences have provided methods and concepts (such as zoning) to a wider EB-MSM context. The assignment of values to biophysical features of the marine environment allows the direct assessment of related management choices and may assist EB-MSM. A range of monetary valuation techniques have been proposed to reduce attributes of goods and services to a single metric. However, in the marine environment such an approach is often over simplistic, and thus less reductive techniques may be necessary. Rather than producing a single metric, the results of non-monetary assessments guide policy allowing weight to be given as necessary to potential areas of conflict and consensus. Strategies to take into account climate change effects and geohazard risks in EB-MSM have been applied or proposed worldwide. EB-MSM regimes must be alert to such risks and flexible to account for changes.

Udgivelsesdato: Juli The exponential growth of off-shore mariculture that has occurred worldwide over the last 10 years has raised concern about the impact of the waste produced by this industry on the ecological integrity of the sea bottom. Investigations into this potential source of impact on the biochemistry of the sea floor have provided contrasting results, and no compelling explanations for these discrepancies have been provided to date. To quantify the impact of fish-farm activities on the biochemistry of sediments, we have investigated the quantity and biochemical composition of sediment organic matter in four different regions in the temperate-warm Mediterranean Sea: Akrotiri Bay (Cyprus), Sounion Bay (Greece), Pachino Bay (Italy), and the Gulf of Alicante (Spain). In these four study regions, the concentrations of phytopigments, proteins, carbohydrates, and lipids in the sediments were measured, comparing locations receiving wastes from fish farms to control locations in two different habitats: seagrass beds and soft nonvegetated substrates. Downward fluxes were also measured in all of the regions, up to 200 m from the fish farms, to assess the potential spatial extent of the impact. In all four regions, with the exception of seagrass sediments in Spain, the biochemistry of the sediments showed significant differences between the control and fish-farm locations. However, the variables explaining the differences observed varied among the regions and between habitats, suggesting idiosyncratic effects of fish-farm waste on the biochemistry of sediments. These are possibly related to differences in the local physicochemical variables that could explain a significant proportion of the differences seen between the control and fish-farm locations. Biodeposition derived from the fish farms decreased with increasing distance from the fish-farm cages, but with different patterns in the four regions. Our results indicate that quantitative and qualitative changes in the organic loads of the sediments that arise from intensive aquaculture are dependent upon the ecological context and are not predictable only on the basis of fish-farm attributes and hydrodynamic regimes. Therefore, the siting of fish farms should only be allowed after a case-by-case assessment of the ecological context of the region, especially in terms of the organic matter load and its biochemical composition.

19 pages, 10 figures, 2 tables, 1 appendix, Analyses of the total organic carbon (TOC), total nitrogen (TN), C/N ratio and isotopic (δ 13C and δ 15N) composition of organic matter (OM) in surficial sediments, integrated with hydrographic measurements, have been used to evaluate the sources and distribution of sedimentary organic matter on the Catalonian shelf and slope (northwest Mediterranean Sea). We examined the effects of the variations on meiofauna. Settled OM in February, April and October displayed δ 13C relatively closer to marine algae (mean −22.4 ‰ ± 0.1) than that in July (−23.3, −23.7 and −22.7 ‰ at 60, 600 and 800 m, respectively). Lowest δ 13C (−23.7 ‰) and high C/N (~10), indicative of mixed continental and marine organic contributions, were detected principally at the head of the Buscarró Canyon (at 600 m) in July, ca. 2–3 months after the maximum river discharge. We observed significant changes in total meiofaunal density among seasons in the canyon, with the highest values in July and October. On the adjacent slope at 800 m there was no significant increase of total meiofauna in those months. Although export of marine organic matter from surface layers was the main food source in the study area (on average 71.2 % estimating marine and terrestrial OC by binary models; 68–71 % at the most by SIAR models), advection of organic matter from the continental edge and/or resuspension of organic matter along submarine canyons may seasonally alter the composition of deposits on the slope, particularly in July with % OC of terrestrial origin reaching 48.7 % in Buscarró canyon, shifting the basal food-web of deep ecosystems, This study was carried out within the framework of the Spanish funded BIOMARE project (CTM2006-13508-CO2-02/MAR: Identification of BIOmarkers of the anthropogenic impact on MARine communities: an ecosystemic approach) and ANTROMARE (CTM2009-12214-C02-01-MAR)

We investigated the impact of fish farm biodeposition on benthic bacteria, thraustochytrid protists, and heterotrophic protozoa (nanoflagellates and ciliates) in an oligotrophic area of the Mediterranean Sea. The fish farm impact was investigated both on a seagrass (Posidonia oceanica) bed and on soft bottom sediments. In both systems, sediment samples were collected with a multicontrol sampling strategy (i.e., beneath the fish farm and at three control sites per system). The uneaten food pellets supplied to the fish determined the accumulation of sediment organic matter and the enhancement of protein content in impacted sediments (both seagrass bed and soft sediments). In both systems, the abundance and biomass of heterotrophic protists increased significantly beneath the fish farm, but the structure of the protist assemblages responded differently in vegetated and unvegetated sediments. Thraustochytrid abundance increased significantly in impacted seagrass. These results provide evidence that the structure of protist assemblages respond significantly to fish farm biodeposition and indicate that the monitoring of these benthic components provides complementary information for the assessment of the fish farm impact on the benthic systems.

Measurements of secondary production of meiofaunal assemblages are limited, and for most seagrass systems no information is available yet. In the present study meiofaunal production was estimated in a Posidonia oceanica bed in the NW Mediterranean Sea using the summation of biomass increments and different equations based on the production:biomass ratio (i.e. biomass turnover). To- tal meiofaunal production ranged from 7.5 to 13.2 gC m -2 yr -1 , according to the approach utilised (mean value 10.0 ± 1.9 gC m -2 yr -1 , median value 9.6 gC m -2 yr -1 ). These values are among the high- est reported worldwide, indicating that seagrass systems are hot spots of meiofaunal production. De- spite the numerical dominance of nematodes, harpacticoid copepods were responsible for about 50% of total meiofaunal production, followed by polychaetes and nematodes (34 and 12%, respectively). Daily meiofaunal production rates were highest in February-March (21.3 mgC m -2 d -1 ), late May-June (31.4 mgC m -2 d -1 ) and October-December (44.6 to 52.0 mgC m -2 d -1 ). Analysis of daily secondary production of the dominant taxa suggested that different meiofaunal components dominated in differ- ent periods. During February-March, May-June and September-October harpacticoid copepods dis- played highest production rates, but in November and December daily meiofaunal production was largely accounted for by polychaetes and nematodes. Temporal analysis of total meiofaunal produc- tion also revealed that, conversely to what is expected for temperate environments, only ca. 15% of the meiofaunal carbon was produced in summer, whereas 23% was observed in spring and 45% in au- tumn. Temporal changes in total meiofaunal daily production were apparently not dependent upon temperature, but rather reflected changes in the content and bio-availability of sediment organic mat- ter in the seagrass bed. The seagrass P. oceanica was responsible, together with microphytobenthos, for high primary production values (169 to 300 gC m -2 yr -1 ). The fraction of total benthic primary pro- duction potentially consumed by meiofauna (as a measure of seagrass trophic efficiency) ranged from 10 to >50%. These estimates provide evidence of the relevance of meiofauna in benthic energy flows. At the same time, the production efficiency in the Posidonia bed (calculated by the ratio of total meio- faunal production to total primary production) was only 3.0 to 5.3%. These values, comparable to those observed in estuarine/organic-rich systems, are 2 to 10 times lower than those estimated in Cymod- ocea nodosa or Zostera noltii seagrass meadows, indicating that the Posidonia system is less efficient than other seagrass systems in channelling primary production to higher trophic levels.

We investigated the impact of fish farming on the benthic biota of 2 habitats (sea- grass meadows of Posidonia oceanica and non-vegetated soft bottoms), by examining in detail the nematode assemblages, and the effects of organic enrichment on their abundance, diversity (spe- cies richness and trophic diversity), community structure and individual size. All investigated faunal variables differed significantly between impact and control sediments, except for indi- vidual nematode biomass. Nematodes displayed reduced biodiversity beneath the investigated fish farms in both vegetated and non-vegetated habitats. The nematode genera Richtersia, Desmoscolex and Halalaimus were highly sensitive to biodeposition and disappeared almost com- pletely in farm sediments, whereas other genera such as Daptonema and Prochromadorella largely increased their relative abundance. The impact of biodeposition was investigated also in terms of K-dominance curves and functional variables (life strategies as maturity index, and func- tional [i.e. trophic] diversity) which showed that nematodes are very sensitive to this kind of envi- ronmental disturbance. Our results indicate that the analysis of nematode assemblage composi- tion, the life traits of the dominant species and the presence/disappearance of certain nematode species represent a reliable tool for monitoring the quality state of marine sediments exposed to fish-farm organic wastes.&nbsp

To study the impact of organic enrichment and high biodeposition caused by intensive fish farming in coastal sediments, meiofaunal samples were collected on a monthly basis between March and October 1997 at two stations of the Gaeta Gulf: One under the Farmocean cage (2000 m3), while the other (the control) was located at about 1 km from an area not impacted by fish farming. The fish farm contained about 120 000 Dicentrarchus labrax (density 18 kg m -3). The most evident changes in the benthic habitat under the cage were a large accumulation of primary organic material (phytopigment concentrations up to 44 μg g-1), changes in sedimentary organic matter composition (increased lipid levels related to the composition of the fish diet), and a strong reduction of redox potential values, which resulted in a significant reduction of meiofaunal penetration depth into the sediments. Organic loads had a clear impact on meiofaunal densities, which were 50% lower under the cage than at the control site (1112 ± 118 and 2160 ± 339 ind. 10 cm-2, respectively). Compared with the control, farm sediments also showed an increased importance of copepods, which dominated the meiofauna together with nematodes (both 39% of the total density) and polychaetes (17%). The removal of the fish farm from the site on July 1997 allowed an analysis to be made of the initial short and medium-term recovery of the assemblages. After two months, meiofaunal densities were closer to the control (about 30% recovery). Community structure recovered only partially to the characteristics typical of the study area, with increased importance of nematodes (about 70% of total density) and reduced copepod contribution, but it was still characterized by a lower number of taxa after four months. These data suggest that meiofaunal recovery after fish farm disturbance is rapid, but far from complete after four months. © 2000 International Council for the Exploration of the Sea.

We studied the initial impact of organic loads due to the biodeposition of a new fish farm in a non-impacted coastal area of the Tyrrhenian Sea (Western Mediterranean). Sediment chemistry and meiofaunal assemblages were investigated from July 1997 to February 1998 on a monthly basis at two stations: the first was located under the fish farm, while the second was at about 1 km distance, and served as control. Variations in the biochemical composition of the sedimentary organic matter and meiofaunal community structure were also related to changes in reared fish biomass. The presence of the cage-induced rapid changes in the benthic compartment: the sediments reached rapidly (i.e., after only 6 weeks) reducing conditions. A significant accumulation of biopolymeric carbon was observed beneath the cage both at the beginning of this study and 5-7 months after cage disposal and appeared to be related to the fish-farm production cycle. Sedimentary proteins and lipids resulted to be good descriptors of medium-term fish-farm impact. Changes in the sediment conditions beneath the cage determined a significant reduction of the total meiofaunal density (on average for 70%). Most meiofaunal taxa, including nematodes, copepods and ostracods displayed a significant decrease in the farm sediments within 3 months after cage installation. Kinorhynchs appeared extremely sensitive to reducing conditions of the sediments and disappeared almost completely, whereas polychaete densities remained unvaried. After initial impact meiofaunal assemblages responded to organic enrichment recovering, at least partially, their apparent structural characteristics. These data indicate that studies carried out several months after cage deployment might underestimate the actual impact on benthic assemblages. Copyright (C) 1999 Elsevier Science Ltd.

Several diagnostic genetic markers were identified in Pomatoschistus marmoratus and P. tortonesei using polyacrylamide gel electrophoresis (PAGE) of allozymes. Twenty-one loci were resolved, including the electrophoretic pattern of muscle proteins. The MDH*, PGM1,2*, EST-1,2*, FUM* and PGI-2* loci exhibited different alleles which were fixed for the two species being analysed. Genetic distance, as calculated by Nei's index, showed a value of 0.413. Environmental hypersalinity, could have influenced the geographical distribution of P. tortonesei.

International audience; The worldwide exponential growth of off-shore mariculture is raising severe concerns about the impacts of this industry on marine habitats and their biodiversity. We investigated the metazoan meiofaunal response to fish farm impact in four regions of the Mediterranean Sea. Meiofaunal assemblages were investigated in two habitats (seagrass meadows of and non-vegetated soft bottoms) comparing sites receiving faeces and uneaten food pellets from fish farms to control sites. We report here that, consistently across different regions, the meiofaunal abundance typically responded positively to fish-farm effluents. Biodeposition caused also significant changes in assemblage structure and the reduction in the richness of higher meiofaunal taxa, but the multivariate analysis of variance revealed that the effects were region- and habitat- specific. In non-vegetated systems, three of the four regions investigated displayed significant effects of the fish farms on richness of meiofaunal taxa. In vegetated habitats, meiofauna did not respond to biodeposition (except in one region), suggesting that seagrass meadows can mask the effects of fish-farm effluents on benthic biodiversity. We conclude that different indicators of fish-farm impact are needed in vegetated and non-vegetated benthic systems.

Holmer, Marianne et al., This paper provides a synthesis of the EU project MedVeg addressing the fate of nutrients released from fish farming in the Mediterranean with particular focus on the endemic seagrass Posidonia oceanica habitat. The objectives were to identify the main drivers of seagrass decline linked to fish farming and to provide sensitive indicators of environmental change, which can be used for monitoring purposes. The sedimentation of waste particles in the farm vicinities emerges as the main driver of benthic deterioration, such as accumulation of organic matter, sediment anoxia as well as seagrass decline. The effects of fish farming on P. oceanica meadows are diverse and complex and detected through various metrics and indicators. A safety distance of 400 m is suggested for management of P. oceanica near fish farms followed by establishment of permanent seagrass plots revisited annually for monitoring the health of the meadows. © 2008 Elsevier Ltd. All rights reserved.

We have investigated the impact of a large mussel farm on the benthic environment using a battery of benthic indicators of environmental quality (including biochemical, microbial and meiofaunal parameters). These were analysed through a multi-control sampling strategy over one year. The differences across the seasons are typically higher than those between the impacted and the control stations. No effects are seen in terms of the sediment oxygen penetration and the downward fluxes (as the total mass, organic and phytopigment fluxes). The indicators based on the biochemical compositions of the sediment organic matter and the microbial parameters also show no evidence of the eutrophication process, except as a slight increase in the bacterial density in the sediments beneath the long-lines of the farm during the period of highest mussel stocks. Finally, no effects are observed in terms of the benthic faunal indicators, as the meiofaunal abundance, the community structure and the taxa richness are all indistinguishable between the farm sediments and the controls. These results show that mussel farming in the investigated system is eco-sustainable and does not significantly alter the coastal marine ecosystem, both in terms of the functioning and the trophic state. The battery of indicators selected in this study represents a useful tool for the monitoring of the potential ecological impact of mussel farms, towards guaranteeing the sustainable development of aquacultures in shallow coastal environments.

The use of artificial substrates for monitoring environmental quality and contaminant impact has been repeatedly suggested, but little information is yet available on the applicability and the sensitivity of this approach. One of the crucial points to be addressed for using artificial substrates, as tools mirroring actual benthic community state, is assessing whether, and how, they reflect in situ conditions characterising natural sediments. In this study we investigated short-term dynamics of meiofaunal colonisation on artificial substrates (bottle brushes) deployed in impacted and "pristine" (control) sites. Meiofaunal colonisation reached a threshold level after 4-6 days in both impacted and control sites but with significantly higher densities in artificial substrates deployed in the control site. Meiofaunal parameters in artificial substrates reflected those of meiofaunal assemblages inhabiting natural sediments where artificial substrates were deployed. Colonised artificial substrates were then transplanted from impacted to control sites. This caused a significant increase of meiofaunal abundance, which after 5 days reached values indistinguishable from the non-impacted control. Given the rapid colonisation time, meiofaunal sensitivity to changing environmental conditions, it can be concluded that artificial substrates can represent an useful tool to be further developed for routine and low-cost monitoring studies aiming at integrating biological indicators of environmental quality.

A previous investigation on fish-farm biodeposition effects on benthos, carried out in the Gaeta Gulf (northwestern Mediterranean Sea), revealed a strong impact on meiofaunal assemblages. This study implements these findings by examining in detail the nematode assemblage and its response to organic enrichment from the start of a fish farm activity to the conclusion of the fish rearing cycle. Density, community structure and individual size were utilised for univariate (genus, trophic diversity and abundance patterns) and multivariate analyses (MDS) in order to identify the best descriptors of impact and the response of the nematode assemblages. Nematodes displayed significantly reduced densities, diversity and richness in sediments beneath fish farms. The impact of biodeposition was evident not only from structural community parameters but also in terms of functional indices. Forty-five days after starting fish farming, an increase of the nematode individual biomass was observed. MDS ordination pointed out the presence of two different nematode communities in disturbed sediments and in the control site. These results were substantiated by the analysis of the temporal changes of k-dominance curves, the maturity index and, to a lesser extent, by the index of trophic diversity. Some nematode genera were highly sensitive to biodeposition (Setosabatieria, Latronema and Elzalia) and disappeared almost completely in farm sediments, whereas other genera largely increased their dominance (Sabatieria, Dorylaimopsis and Oxystomina). This study indicates that nematodes are very sensitive to this kind of environmental disturbance. The use of simple tools, such as the k-dominance analysis and maturity index, are recommended for monitoring of aquaculture impact. (C) 2001 Elsevier Science Ltd. All rights reserved.

Diet composition, feeding rhythms, gastric evacuation rates, daily rations of Diplodus puntazzo (Gmelin 1789) and Sarpa salpa (Linneo 1758) juveniles were studied in order to investigate their trophic ecology, niche breadth and overlap. These Sparids were collected in the Stagnone di Marsala (Western Sicily), in April 1997, in a 24 hour sampling period. Gastric content of 86 specimens of D. puntazzo (standard length = 31.9 ± 6.6 mm; body wet weight = 1.0 Ī 0.5 g) and of 100 specimens of S. salpa (standard length = 32.3 ± 2.9 mm; body wet weight = 0.6 Ī 0.2 g) were examined. Amphipoda and Tanaidacea were the most frequent prey items in stomach content of D. puntozzo, while Hydrozoa, Bryozoa and Rhodophycaea were the most frequent prey items in that of S. salpa. Both species displayed high frequency of occurrence (% Fr) of Copepoda and Ascidiacea larvae. A unimodal trend of daily rhythm of food consumption was deduced for both species. Gastric evacuation of juvenile D. puntazzo was best described by a square root model, with a gastric evacuation rate R= 0.011 ± 0.001 (r = 0.84; n = 28; P < 0.001). Similarly, gastric evacuation of S. salpa followed a square root model, with a gastric evacuation rate R=0.014 ± 0.001 (r = 0.90; n = 42; P < 0.001). The amount of food consumed daily, calculated according to Pennington’s model, was 0.0133 g dry weight g−1 body dry weight for D. puntazzo and 0.0159 g dry weight g−1 body dry weight for S. salpa, equal to 1.3% and 1.6% of the average body dry weight, respectively. Standardised Levins’ index (BA), calculated on percent volume (% V), suggested that juveniles of D. puntazzo have a niche breadth (mean standardised Levins’ index = 0.2 ± 0.02) larger than the one of S. salpa (mean standardised Levins’ index = 0.1 ± 0.01) at most sampling times. Juvenile specimens of these two Sparids presented a niche overlap at 4 pm, in correspondence with their feeding peak (Simplified Morisita’s index C H = 0.9). Feeding habits of D. puntazzo and S. salpa and their niche overlap are discussed in comparison with literature available on the same field.

Meiofaunal community structure in coastal sediments of Terra Nova Bay (Ross Sea) was related to quantity and biochemical composition of sedimentary organic matter. The sediments were generally characterized by large amounts of chloropigments and labile compounds (dominated by proteins), indicating high inputs of primary organic matter. Meiofaunal densities were very high and comparable to those from the most productive areas worldwide. Sediments with high densities of the scallop had low meiofaunal densities especially in the top 2 cm, suggesting that scallop clapping contributed to meiofauna resuspension. However, it is not possible to exclude the probability that meiofauna are part of the scallop beds apparently have an important role in structuring meiofaunal communities with nematodes dominant where Adamussium colbecki is absent, and gastrotrichs dominant (44–51%) in A. colbecki beds, reaching the highest density reported so far.