Exploring spatio-temporal changes in the demersal and benthopelagic assemblages of the north-western Ionian Sea (central Mediterranean Sea)

Abstract

An exploration of the structure of demersal and benthopelagic assemblages in the northwestern Ionian Sea was carried out by means of a set of statistical analyses. Self-organising map (SOM) and clustering methods applied to 183 taxa and their biomass (kg km −2) provided the classification of 1288 experimental hauls exploring the bathymetric range 10−800 m from 1995 to 2012. Six clusters were identified according to their similarities in species abundances (biomass), confirming the depth gradient as the main structuring agent. In order to identify key representative species in each cluster, the taxa were ranked by means of an indicator value index (IndVal) and the contribution of species to beta diversity (BD). Furthermore, the clusters were described by means of environmental and fishing characteristics. Particular habitat type, distance to canyon and fishing effort segregated the assemblages on the coastal shelf and slope. Temporal differences were detected in 2 bathyal groups, which were most likely affected by the 1990s environmental change in the deepwater circulation known as the Eastern Mediterranean Transient. The overall total BD in the study area was calculated as 0.79, with a temporal decrease observed at a rate of 0.7% yr −1. The approaches used are useful to identify and characterize the species aggregations inside complex faunal assemblages, without a priori assumptions about data distribution. These results can be a starting point for defining functional groups for Mediterranean food web modelling approaches, as well as for identifying indicator species to assess the environmental status in the context of the Marine Strategy Framework Directive.

Ecosystem functioning of two marine food webs in the North‐Western Ionian Sea (Central Mediterranean Sea)

“…However, some information gaps were detected for low trophic level groups, such as suprabenthic crustaceans, polychaetes, macrobenthic invertebrates, and gelatinous plankton, which should be addressed by future research goals in the area. Despite the common model structure for the two food webs, some differences emerge as a consequence of differences in geomorphological and hydrographic conditions influencing occurrence, distribution, and abundance of marine species in the NWIS (Carlucci et al, ).…”

“…The remaining 147 species lacking in diet information were successively grouped according to their life‐history traits, information from qualitative diets, and habitat preferences identified by a self‐organizing map analysis (Carlucci et al, ). However, due to their ecological and commercial importance, several species were ungrouped and defined as a single FG: the blackmouth catshark ( Galeus melastomus ), the hake ( Merluccius merluccius ), the red mullet ( Mullus barbatus ), the anglers ( Lophius piscatorius and L. budegassa ), the bluntsnout grenadier ( Nezumia sclerorhynchus ), the red giant shrimp and blue and red shrimp ( Aristaeomorpha foliacea and Aristeus antennatus , respectively), the deep‐water rose shrimp ( Parapaeneus longirostris ), and the golden shrimp ( Plesionika martia ).…”

“…The Common Fisheries Policy (CFP EU, ) worries about the loss of biodiversity and the need to study biodiversity in a holistic way to maintain marine habitats in a healthy, clean, productive, and resilient condition in order to achieve Good Environmental Status (GES) by 2020, as required by the EU Marine Strategy Framework Directive (EU, ). Within this context, the investigated area is characterized by great environmental variability (Carlucci et al, and references therein) and by the presence of different habitats (D'Onghia et al, ; Calculli, Capezzuto, Carlucci, Carluccio, Grehan et al, ). Such variability is reflected in the diversity of both benthopelagic and demersal assemblages (Maiorano et al, ) as well as the spatial distribution of the fishing fleets that exploit the demersal resources (Russo et al, ).…”

The Social Role of Vocal Complexity in Striped Dolphins

“…The Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea) covers an area of approximately 14,000 km 2 from Santa Maria di Leuca to Punta Alice (Figure 1). A narrow continental shelf with a steep slope and several channels characterizes the western sector, while the eastern sector shows descending terraces toward the "Taranto Valley, " a NW-SE submarine canyon with no clear bathymetric connection to a major river system (Capezzuto et al, 2010;Russo et al, 2017;Carlucci et al, 2018a). The striped dolphin regularly occurs in the northernmost portion of the Taranto Valley (Azzolin et al, 2020), most likely attracted by the high productivity of the sub-marine canyon system and its upwelling currents (Carlucci et al, 2018c).…”

A metabarcoding approach for the feeding habits of European hake in the Adriatic Sea

“…Overall, approaches based on food webs can provide a fisheries management advice based on broader and more realistic context than single species approaches (see Link, ; Mackinson, Deas, Beveridge, & Casey, ; Walters, Christensen, Martell, & Kitchell, ). Moreover, the study of feeding habits is necessary and useful to understand mechanisms and processes which structure and influence fish assemblages (Carlucci et al., ; Eriksson et al., ; Kotrschal & Thomson, ).…”