Citation: Azzurro E, Ballerini T, Antoniadou C, Aversa GD, Souissi JB, Blašković A, Cappanera V, Chiappi M, Cinti M-F, Colloca F, Cvitković I, D’Amen M, Despalatović M, Di Franco A, Dimitriadis C, Dragičević B, Fanelli E, Figuerola L, Fortibuoni T, Franzitta G, Garrabou J, Geloso T, Ghanem R, Gori A, Hervat M, Izquierdo-Muñoz A, Linares C, La Mesa G, Merotto L, Micallef R, Miliou A, Minelli A, Moschella P, Pannacciulli F, Panzalis P, Pavičić M, Petrou A, Ramos-Esplá AA, Saponari L, Scarcella G, Spoto M, Stagličić N, Vrdoljak D, Weitzmann B and Schembri PJ (2022) ClimateFish: A Collaborative Database to Track the Abundance of Selected Coastal Fish Species as Candidate Indicators of Climate Change in the Mediterranean Sea. Front. Mar. Sci. 9:910887. doi: 10.3389/fmars.2022.910887 DATA REPORT published: 06 July 2022 doi: 10.3389/fmars.2022.910887

Marine litter is one of the main sources of anthropogenic pollution in the marine ecosystem, with plastic representing a global threat. This paper aims to assess the spatial distribution of plastic macro-litter on the seafloor, identifying accumulation hotspots at a northern Mediterranean scale. Density indices (items km–2) from the MEDITS trawl surveys (years 2013-2015) were modelled by generalized additive models using a Delta-type approach and several covariates: latitude, longitude, depth, seafloor slope, surface oceanographic currents and distances from main ports. To set thresholds for the identification of accumulation areas, the percentiles (85th, 90th and 95th) of the plastic spatial density distribution were computed on the raster data. In the northern Mediterranean marine macro-litter was widespread (90.13% of the 1279 surveyed stations), with plastic by far the most recurrent category. The prediction map of the plastic density highlighted accumulation areas (85th, 90th and 95th percentiles of the distribution, respectively, corresponding to 147, 196 and 316 items km–2) in the Gulf of Lions, eastern Corsica, the eastern Adriatic Sea, the Argo-Saronic region and waters around southern Cyprus. Maximum densities were predicted in correspondence to the shallower depths and in proximity to populated areas (distance from the ports). Surface currents and local water circulation with cyclonic and anticyclonic eddies were identified as drivers likely facilitating the sinking to the bottoms of floating debris.

1 National Research Council, Istituto per le Risorse Biologiche e le Biotecnologie Marine (CNR-IRBIM), Mazara del Vallo (TP), Italy. (FC) (Corresponding author) E-mail: francesco.colloca@cnr.it. ORCID iD: https://orcid.org/0000-0002-0574-2893 (GG) E-mail: germana.garofalo@iamc.cnr.it. ORCID iD: https://orcid.org/0000-0001-9117-6252 2 Department of Biology and Biotechnology “C. Darwin” BBCD, Sapienza University of Rome, Italy. 3 Stazione Zoologica Anton Dohrn, Lungomare Cristoforo Colombo (ex complesso Roosevelt), 90142 Palermo, Italy. (GM) E-mail: giacomo.milisenda@szn.it. ORCID iD: https://orcid.org/0000-0003-1334-9749 4 Department of Biology, University of Bari Aldo Moro, Bari, Italy. (FC) E-mail: francesca.capezzuto@uniba.it. ORCID iD: https://orcid.org/0000-0002-1498-0228 5 Department of Life and Environmental Sciences, Via Tommaso Fiorelli 1, University of Cagliari, Cagliari, Italy. (AC) E-mail: alessandrocau@unica.it. ORCID iD: https://orcid.org/0000-0003-4082-7531 6 MARBEC IFREMER, CNRS, IRD, Université Montpellier 2, Avenue Jean Monnet, CS 30171, 34203 Sète Cedex, France. (AJ) E-mail: Angelique.Jadaud@ifremer.fr. ORCID iD: https://orcid.org/0000-0001-6858-3570 7 Hellenic Agricultural Organization-DEMETER, Fisheries Research Institute of Kavala, 64007 Nea Peramos, Kavala, Greece. (SK) E-mail: skipariss@inale.gr. ORCID iD: https://orcid.org/0000-0002-0587-8889 8 Ministry for the Environment, Sustainable Development and Climate Change, Marsa, Malta. (RM) E-mail: reno.micallef@gov.mt. ORCID iD: https://orcid.org/0000-0003-1921-508X 9 Department of Biological, Geological and Environmental Sciences (BIGEA), University of Bologna, Bologna, Italy. (SM) E-mail: stefano.montanini2@unibo.it. ORCID iD: https://orcid.org/0000-0002-7286-7805 (MV) E-mail: maria.vallisneri@unibo.it. ORCID iD: https://orcid.org/0000-0002-6323-4328 10 Department of Fisheries and Marine Research (DFMR), Nicosia, Cyprus. (IT) E-mail: ithasitis@dfmr.moa.gov.cy. ORCID iD: https://orcid.org/0000-0002-0940-2212 11 Environmental Protection Agency Tuscany Region (ARPAT), Settore Mare, Livorno, Italy. (AV) E-mail: a.voliani@arpat.toscana.it. ORCID iD: https://orcid.org/0000-0002-0905-6284 12 Institute of Oceanography and Fisheries. Set. I. Mestrovica 63, 21000 Split, Croatia. (NV) E-mail: vrgoc@izor.hr. ORCID iD: https://orcid.org/0000-0002-5208-4512 13 COISPA Tecnologia & Ricerca, Via dei Trulli 18-20, 70126 Bari, Italy. (WZ) E-mail: zupa@coispa.eu. ORCID iD: https://orcid.org/0000-0002-2058-8652 14 Instituto Español de Oceanografía, Centre Oceanogràfic de les Balears, Palma de Mallorca, Spain. (FO) E-mail: xisco.ordinas@ba.ieo.es. ORCID iD: https://orcid.org/0000-0002-2456-2214

Trawling pressure and environmental changes may affect the composition of fish assemblages. Our knowledge on large spatio-temporal patterns of demersal fish composition remains incomplete for the Mediterranean Sea. We investigated (1) the spatio-temporal stability of demersal assemblages, (2) the relationships between these assemblages and potential structuring factors (trawling pressure and environmental conditions) in order to assess the dynamic of the assemblage structure at the scale of the northern Mediterranean Sea. We analysed a dataset of 18062 hauls from 10 to 800 m depth performed annually during the last two decades across 17 Geographical Sub-Areas (GSAs) (MEDITS program). A multi-table analysis (STATICO-CoA) evidenced a strong inter-GSAs stability in the organization of assemblages, with specificities for some GSAs. The most stable structuring factors were linked to combined gradients of chlorophyll a, phytoplancton carbon biomass and temperature, inversely correlated with depth, salinity and nutrient gradients (axis 1 of the STATICO-CoA compromise, 93.74% of the total variability). A common pattern linking the distribution of species to these environmental gradients was evidenced for most of the 17 GSAs. Estimate of trawling pressure showed a minor role in the organization of the assemblages for the spatial scale and years investigated (axis 2. 4.67%).

In this study we investigated the spatio-temporal distribution of gurnards (8 species of Triglidae and one species of Peristediidae) in the northern Mediterranean Sea using 22 years of MEDITS bottom trawl survey data (1994-2015). Gurnards showed significant differences in terms of abundance, dominance and composition among geographical sub-areas and ecoregions, with the highest relative biomass (BIy) being found in Malta, eastern Corsica, the Balearic Islands and the eastern Ionian Sea. The lowest gurnards BIy were observed in the highly exploited areas of the western Mediterranean and the Adriatic Sea, where the largest number of species with a negative linear trend in BIy was also found. The temporal trends in species abundances highlighted a general decrease for the coastal species (C. lucerna, C. lastoviza, C. obscurus) as compared with the species inhabiting the deep continental shelf and slope (T. lyra, P. cataphractum). The results provide for the first time an overview of the spatiotemporal trend in the abundance of gurnards over the wide spatial scale of the northern Mediterranean Sea, also suggesting the possible use of these species as indicators for monitoring the impact of fishing pressure on demersal fish assemblages.

The aristeids Aristaeomorpha foliacea and Aristeus antennatus are two species of great economic importance in the Mediterranean Sea, where they are exploited almost exclusively by bottom trawlers. We analysed their geographical and inter-annual patterns using data collected, following a standardized protocol, during the MEDITS international experimental bottom trawl surveys. The data used consisted of standardized abundance and biomass indices, size structure and individual biological information collected in the northern Mediterranean for more than two decades. Several univariate and multivariate methodologies were used to analyse the data. The current study confirms previous findings, such as the longitudinal gradient in the relative presence of the aristeids, but also offers additional information for a better understanding of the intrinsic variability of the data over the years and between areas. Moreover, geographical variability in the somatic condition index is discussed, taking into account the role of environmental conditions and fishing pressure. The large geographical variability found for both species in this regional approach reflects the importance of additional studies at a small-scale geographical level. Such studies could be particularly important for managing and ensuring the stability of these species, for which large regional approaches may be inadequate.

The main characteristics concerning the distribution of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, the deep-water rose shrimp, Parapenaeus longirostris, and the Norway lobster, Nephrops norvegicus, are studied in the European Mediterranean waters. The study is based on data collected under the MEDITS trawl surveys from 1994 to 2015 from the Gibraltar Straits to the northeastern Levantine Basin (Cyprus waters). The observed differences can be interpreted as different responses to environmental drivers related to the differing life history traits of the two species. In fact, N. norvegicus is a long-living, benthic burrowing species with low growth and mortality rates, while P. longirostris is an epibenthic, short-living species characterized by higher rates of growth and mortality.

The effective management and conservation of fishery resources requires knowledge of their spatial distribution and notably of their critical life history stages. Predictive modelling of the European hake (Merluccius merluccius L., 1758) distribution was developed in the south-central Mediterranean Sea by means of historical fisheries-independent databases available in the region. The study area included the international waters of the south-central Mediterranean Sea and the territorial waters of Italy, Malta, Tunisia and Libya. Distribution maps of predicted population abundance index, and probabilistic occurrence of recruits and large adults were obtained by means of generalized additive models using depth and seafloor characteristics as predictors. Presence/absence data of the two life stages was obtained using threshold values applied to the mean weight of the survey catches. Modelling results largely matched previously reported knowledge on habitat preference of the species and its critical life phases. Hake recruits showed an occurrence peak at 200 m depth with preference for soft bottoms. Large adults preferred deeper and harder bottom substrates. Prediction maps allowed to improve our knowledge on the distributional patterns of one of the most important shared stocks in the south-central Mediterranean. This knowledge is essential for an appropriate development of regional-spatial-based management plans.

The Mediterranean Sea is characterized by large scale gradients of temperature, productivity and salinity, in addition to pronounced mesoscale differences. Such a heterogeneous system is expected to shape the population dynamics of marine species. On the other hand, prevailing environmental and climatic conditions at whole basin scale may force spatially distant populations to fluctuate in synchrony. Cephalopods are excellent case studies to test these hypotheses owing to their high sensitivity to environmental conditions. Data of two cephalopod species with contrasting life histories (benthic octopus vs nectobenthic squid), obtained from scientific surveys carried out throughout the Mediterranean during the last 20 years were analyzed. The objectives of this study and the methods used to achieve them (in parentheses) were: (i) to investigate synchronies in spatially separated populations (decorrelation analysis); (ii) detect underlying common abundance trends over distant regions (dynamic factor analysis, DFA); and (iii) analyse putative influences of key environmental drivers such as productivity and sea surface temperature on the population dynamics at regional scale (general linear models, GLM). In accordance with their contrasting spatial mobility, the distance from where synchrony could no longer be detected (decorrelation scale) was higher in squid than in octopus (349 vs 217 km); for comparison, the maximum distance between locations was 2620 km. The DFA revealed a general increasing trend in the abundance of both species in most areas, which agrees with the already reported worldwide proliferation of cephalopods. DFA results also showed that population dynamics are more similar in the eastern than in the western Mediterranean basin. According to the GLM models, cephalopod populations were negatively affected by productivity, which would be explained by an increase of competition and predation by fishes. While warmer years coincided with declining octopus numbers, areas of high sea surface temperature showed higher densities of squid. Our results are relevant for regional fisheries management and demonstrate that the regionalisation objectives envisaged under the new Common Fishery Policy may not be adequate for Mediterranean cephalopod stocks. (C) 2017 Elsevier Ltd. All rights reserved.

Cephalopod assemblages at the scale of the entire Mediterranean Sea were analysed using information from 2 decades of standardized scientific bottom trawl surveys. Western and eastern assemblages (6 yr of data) were compared using a combined approach of multivariate ordination techniques and non-linear regressions. These methods enabled us to distinguish assemblages and simultaneously analyse the influence of geographic, bathymetric and environmental (sea surface temperature and chlorophyll a concentration) gradients on observed community patterns. Despite few differences in species composition between sub-basins, the relative contribution of species differed. Bathymetry was the primary structural driver for the cephalopod communities of both basins, and contributed to 3 assemblages (shallow water, upper slope and middle slope). Winter temperature influenced community assemblages more strongly in the western than in the eastern basin, in contrast to a small but consistent winter productivity influence on community assemblages in both basins. Thus, the environmental parameters analysed did not cause an immediate change in cephalopod assemblages, but rather an effect lagged by several months. Differences in the relative importance of environmental drivers show that different processes operate in the 2 basins. These results demonstrate similarities and differences between Mediterranean basins regarding important cephalopod functional groups. This information should help integrative ecosystem management approaches currently used in fisheries and conservation management.

Species diversity is widely recognized as an important trait of ecosystems' functioning and resilience. Understanding the causes of diversity patterns and their interaction with the environmental conditions is essential in order to effectively assess and preserve existing diversity. While diversity patterns of most recurrent groups such as fish are commonly studied, other important taxa such as cephalopods have received less attention. In this work we present spatio-temporal trends of cephalopod diversity across the entire Mediterranean Sea during the last 19 years, analysing data from the annual bottom trawl survey MEDITS conducted by 5 different Mediterranean countries using standardized gears and sampling protocols. The influence of local and regional environmental variability in different Mediterranean regions is analysed applying generalized additive models, using species richness and the Shannon Wiener index as diversity descriptors. While the western basin showed a high diversity, our analyses do not support a steady eastward decrease of diversity as proposed in some previous studies. Instead, high Shannon diversity was also found in the Adriatic and Aegean Seas, and high species richness in the eastern Ionian Sea. Overall diversity did not show any consistent trend over the last two decades. Except in the Adriatic Sea, diversity showed a hump-shaped trend with depth in all regions, being highest between 200-400 m depth. Our results indicate that high Chlorophyll a concentrations and warmer temperatures seem to enhance species diversity, and the influence of these parameters is stronger for richness than for Shannon diversity.

Stefanie Keller*1, Valerio Bartolino2, Manuel Hidalgo1, Isabella Bitetto3, Loredana Casciaro3, Antonio Esteban4, Maria Cristina Follesa5, Cristina Garcia6, Germana Garofala7, Marios Iosifides8, Angelique Jadaud9, Evgenia Lefkaditou10, Porzia Maiorano11, Chiara Manfredi12, Bojan Marceta13, Enric Massutí1, Reno Micallef14, Panagiota Peristeraki15, Giulio Relini16, Paolo Sartor17, Maria Teresa Spedicato3, George Tserpes15, Antoni Quetglas1