Search

Open oceanic systems are affected by the contamination from microplastics (MPs; plastic particles ¡ 5 mm). These particles can resemble plankton in size and colour, and thus be ingested, directly or indirectly, by marine organisms. Few studies exist on the presence of this contaminant in oceanic epipelagic organisms, such as small planktivorous fish, and almost none focused on squid species. The present study investigated MPs abundance and characteristics in five ecologically and commercially important epi- and mesopelagic species from the North-East Atlantic collected off Madeira Island (Scomber colias, Trachurus picturatus, Stenoteuthis pteropus, Ommastrephes caroli, Loligo vulgaris). Visual analysis performed after digestion of the organic material found MPs in 98% of the fish (n=75) with an average content of 8.7 MPs per individual (stomach+intestine). In the three squid species analysed, MPs were found in 100% of the individuals (n=20), with an average content of 8.5 MPs per individual (stomach+gills+ink sac). Fibres were the main particle found, representing over 90% of the MPs in all the species. Differences in MPs content were found between species and between different body compartments. The present results indicate that squids are vulnerable to MPs ingestion as much as planktivorous fish, which have already been suggested as bioindicators for MPs monitoring in pelagic ecosystems. For squids, however, indirect ingestion of MPs through diet might be the primary mechanism of MPs intake. We suggest that trophic transfer of MPs occurs in these marine species. This study provides new knowledge into the level of contamination by MPs in poorly studied species (squids) inhabiting open oceanic waters, an environment still relatively unexplored. These are essential information to understand the ecological threat MPs pose to the marine ecosystem and humans. Also see: https://micro2022.sciencesconf.org/427133/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Ciguatera fish poisoning episodes have been recently reported in the Madeira Archipelago, requiring actions to protect both public health and economic sectors such as tourism and fisheries. Surveys on the occurrence of benthic harmful algal bloom (bHAB) species were performed during three consecutive years (from 2018 to 2020), at Cais do Carvão Bay, Funchal, Madeira. Samples collected on artificial substrates were analyzed for the presence of bHAB species, the seasonal succession of the bHAB community and the effects of abiotic factors on BHAB dynamics. The bHAB community was characterized by the presence of five genera: Gambierdiscus, Ostreopsis, Coolia, Prorocentrum, and Amphidinium. The abundance of the different genera showed marked differences. Ostreopsis displayed cell abundances several orders of magnitude higher than the other genera (841.05 x 103 cells 100 cm-2 (September 2018) and was recorded at all sampling dates. The second most abundant genus was Coolia, followed by Prorocentrum and Amphidinium. Gambierdiscus always showed the lowest cell densities (max. 0.43 x 103 cells 100 cm-2 (September 2018). During summer, Ostreopsis abundances exceeded, in several sampling dates the limits of level of concern for respiratory syndrome outbreaks (20 x 103 cells 100 cm-2) as referred to in the literature. In situ recorded abiotic data suggests that the increase of Ostreopsis densities could be linked to an increase in water temperature during summer. These results confirm Cais do Carvão Bay, as a potential high-risk area for bHAB development, especially concerning the genus Ostreopsis.