Can oviposition on marine litter pose a threat to marine fishes?

Interaction of elasmobranchs with litter in South Brazil: ingestion and oviposition patterns

Elasmobranchs, one of the most endangered animal groups, have been affected by different anthropogenic stressors, including marine litter. To better understand the interactions of elasmobranchs with litter we analyzed the gastrointestinal tract of sharks and examined skate nest composition in southern Brazil. Among 47 sharks caught in longline fisheries, three had ingested mesoplastic items (FO = 6.4 %); a subsample of 18 of these sharks was assessed for microplastic ingestion, revealing 34 microplastics in 12 individuals (FO = 66 %). Gillnet-captured sharks (n = 7) only ingested three microplastics (FO = 42.85 %). Sixteen skate nests examined for litter interaction presented a total of 269 egg capsules and 1676 litter items. The FO of litter in nests was 100 %, with plastic being the predominant material (96.71 %), mainly fishing lines (85.98 %). While litter ingestion by sharks was less frequent than other groups, litter prevalence in skate nests was high and primarily linked to fishing activities.

Adapting to a pollution hotspot? Catsharks shift to plastic substrates for oviposition

Plastic pollution is widely recognized as one of the major threats to marine ecosystems. However, our knowledge on the ecological interactions between plastic and marine fauna is still limited. Here, we analyzed the substrate preferences for oviposition in the small-spotted catshark (Scyliorhinus canicula) and explored the influence of pollution, environmental conditions, and fishing pressure as potential drivers. For the first time, we report this catshark species using marine debris for oviposition, unraveling a behavioral shift in the oviposition substrate preferences towards plastics, particularly ghost fishing gear, when biological substrates are unavailable. Our results indicate that this behavioral change may be driven by the combined effects of plastic pollution and habitat degradation. Preferences also change with depth, with a larger preference for the hydrozoan Lytocarpia myriophyllum on the continental shelf, followed by sponges, as in this region mesophotic and deep benthic communities are still more abundant although impacted by human pressures. In contrast, on the continental slope, the preference shifts to tube-dwelling polychaetes and plastics, primarily ghost fishing gear, due to the limited availability of biological substrates in this region. We highlight that plastic-fish interactions may become increasingly recurrent as plastic substrates increase and habitat forming invertebrates decline due to trawl fishing and other anthropogenic activities, especially in the Mediterranean Sea. The implications of this behavior for catshark fitness are still largely unknown, which prompts further research concerning the potential impact on its survival and/or dispersal in the plastic age and highlights the urgency of preserving biogenic habitats.

Distribution and composition of seafloor litter and associated macrofouling organisms in the Northeastern Mediterranean Sea

Composition, and density of marine litter and associated macrofouling organisms was assessed in the continental shelf of the Northeastern Mediterranean Sea. A total of 943 litter items weighing 388 kg were collected during 34 hauls. Plastic comprised 72 % of the total litter found on the seafloor. The mean number and weight of ML was 4241 ± 1333 items/km2 and 368 ± 87 kg/km2. Depth and distance from the shore were not identified as a significant factor affecting both the number and weight of litter. A total of 20 fouling species and eggs belonging to Mollusca, Porifera, Cnidaria, Bryozoa, Annelida, Arthropoda, and Chordata were found on marine litter. An alien Mollusca species Pinctada imbricate was also found on plastic litter. Our results confirmed that marine litter is a vector transporting a variety of organisms including alien species and being a threat for the biodiversity and human health in the Mediterranean Sea.

Putting eggs on marine litter: Towards an understanding of a cause for concern

Marine litter, including plastic litter, represent a serious environmental problem at a global scale. Plastics in marine litter have been documented on few occasions as serving as a unique substrate for fish oviposition in the oceans. The main goal of this viewpoint is to add to the previous discussion of fish oviposition and marine litter concerns by pointing out current research needs.

Rajids ovipositing on marine litter: A potential threat to their survival

Marine litter is a complex environmental issue threatening the well-being of multiple organisms. In the present study, we present an overlooked pathway by which marine litter interaction with certain ovigerous skates (Family: Rajidae) communities could compromise their survival. We propose that skates from the genus Sympterygia deposit their egg capsules on marine litter substrates by accident, which are then washed ashore still unhatched. We conducted 10 monitoring surveys on three beaches of La Libertad Region, on the north coast of Peru, looking for marine litter conglomerates to determine the presence of egg capsules. We registered a total of 75 marine litter conglomerates, containing 1595 egg capsules, out of which only 15.9 % were presumably hatched, and 15.8 % were still fresh. Fishing materials were identified as the main item in marine litter conglomerates. We conclude that this behavior could contribute to the decline of Sympterygia communities, although further research is needed.