Potential factors influencing the condition of demersal sharks in the Mediterranean deep sea ecosystems

Ordines, Francesc; Valls, María; Meléndez, María José; Ramírez‐Amaro, Sergio; López, Eduardo; Lloret, Josep; Rodríguez, Mariel; Farriols, M. Teresa; Guijarro, Beatríz; García‐Ruíz, Cristina; Massutı́, Enric

doi:10.1016/j.dsr.2021.103603

Cited by 2 publications

(2 citation statements)

References 78 publications

(120 reference statements)

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“…For some FGs such as dolphins, turtles, pelagic sharks, large pelagic fishes, medium pelagic fishes, sardine & anchovy, bivalves & gastropods, annelids, suprabenthos, gelatinous plankton and zooplankton, the diet composition had to be completed with information from other areas of the Western Mediterranean. In spite of this, some studies developed in this area have revealed that the feeding behaviour of important species such as Merluccius merluccius (Rueda et al, 2019) or Galeus melastomus (Ordines et al, 2021) show differences even at medium spatial scales. Such results highlight that diet data should be improved with studies developed in the Balearic Islands in future research.…”

Section: Parametermentioning

confidence: 99%

Trophic structure and fishing impacts on an oligotrophic ecosystem in the Western Mediterranean: the Balearic Islands

et al. 2023

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Within the context of the ecosystem approach to fisheries management, an ecosystem model was developed for the Balearic Islands in the early 2000s, covering from 0 to 800 m of depth. The aim of the study was to describe the structure and functioning of the ecosystem together with the fishing impacts. The results show that the biomass of the primary producers (PP), mainly dominated by Posidonia oceanica meadows and red algae beds, represented a high percentage of the biomass (39.20%) in the ecosystem. Most of the trophic flows occurred between PP (mostly benthic) and trophic level II. The mixed trophic impact analysis also highlighted a positive impact of the functional groups (FGs) at the base of the food web. Besides, there were important trophic flows between several demersal FGs, and many groups of the pelagic compartment, confirming the importance of the benthopelagic coupling previously reported. The mean trophic level of the catch (mTLc=2.76) was lower than those reported in adjacent areas due to the discard of benthic producers. By excluding benthic PP, the Balearic Islands showed the highest mTLc (3.44) among all the Mediterranean areas modelled, probably due to differences in the trophic structure, lower fisheries exploitation levels and lower development of the purse seine fleet targeting small pelagic fishes. The mean transfer efficiency (21.80%) was double than the global average (10%), which highlights the oligotrophy of the system, the importance of demersal production which has lower rates of transfer through the food web, and a more efficient use of nutrients in the ecosystem. Sponges, one of the most important groups of benthic invertebrates in the Balearic Archipelago, are known to recycle dissolved organic matter, which is reintroduced into the food web similar to the microbial loop, but the magnitude of this and other processes remains still unknown in this area. The present study is a first step to develop spatio-temporal simulations under different exploitation scenarios and to calculate ecological indicators to assess the state of the marine environment in this region.

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Section: Parametermentioning

confidence: 99%

Trophic structure and fishing impacts on an oligotrophic ecosystem in the Western Mediterranean: the Balearic Islands

et al. 2023

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“…In the Mediterranean Sea, reports of ingestion and entanglement in sharks with various degrees of endangerment status have been reported [23,29,30]. Two shark species, the small-spotted catshark Scyliorhinus canicula and the blackmouth catshark Galeus melastomus, are not only commercially important species in the Balearic Islands in the western Mediterranean Sea, but the ecological assessment of these species, such as condition index, could be an indication of ecosystem health [31,32]. S. canicula is the most abundant elasmobranch species on the continental shelf [33].…”

Section: Introductionmentioning

confidence: 99%

Presence and Potential Effects of Microplastics in the Digestive Tract of Two Small Species of Shark from the Balearic Islands

Torres,

Compa,

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et al. 2024

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In recent years, there has been an increase in the reporting of plastic pollution in the marine environment and its effects on marine animals, especially bony fish. However, the prevalence and effect, particularly concerning biomarkers of oxidative stress, in elasmobranchs remain underreported and unknown. In this study, microplastics were observed in two elasmobranch species from the Balearic Islands: the small-spotted catshark (Scyliorhinus canicula) with an average of 4.38 ± 1.77 items per individual, and the blackmouth catshark (Galeus melastomus) with an average of 8.31 ± 2.46 items per individual. Moreover, for the first time, antioxidant and pro-inflammatory responses were determined in the digestive tract of individuals of both species. Specifically, the activation of antioxidant defences, mainly superoxide dismutase activity and glutathione levels, was observed, while the pro-inflammatory marker myeloperoxidase activity was also greater in individuals with a high abundance of microplastic items. Additionally, a significant increase in glutathione S-transferase activity in catsharks with high microplastic ingestion was evidenced, suggesting that the detoxification process was activated. Overall, the results of this study highlight that both catshark species are ingesting microplastics, which, in turn, are causing physiological effects at a cellular level. Considering this, continued monitoring of these species should include the presence of microplastics, and the results from this study can serve as baseline data for future research.

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Potential factors influencing the condition of demersal sharks in the Mediterranean deep sea ecosystems

Cited by 2 publications

References 78 publications

Trophic structure and fishing impacts on an oligotrophic ecosystem in the Western Mediterranean: the Balearic Islands

Trophic structure and fishing impacts on an oligotrophic ecosystem in the Western Mediterranean: the Balearic Islands

Presence and Potential Effects of Microplastics in the Digestive Tract of Two Small Species of Shark from the Balearic Islands

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