Microplastic ingestion cause intestinal lesions in the intertidal fish Girella laevifrons.

We exposed juvenile intertidal fish to different amounts of Poly(styrene-co-divinylbenzene) microplastics in their diet. We fed ten individuals with pellets containing 0.01 g, another ten fish with pellets containing 0.1 g of PS, and ten fish without plastic as control. After 45 days of treatment, the whole intestine was removed, and the histological evaluation started immediately. We evaluated inflammation due to leukocyte infiltration (Lk), circulatory disorders like Hypermeia (Hyp), and regressive changes in the intestinal tissue, assessing Crypt cell loss (Ccl) and Villi cell loss (Vcl). The severity of the lesions increased according to the microplastic concentration. In the fish group feeding on microplastics, we found that leukocyte infiltration and hyperemia were more severe in the higher exposure group compared to the lower exposure; and crypt cell loss and villi cell loss increased significantly due to Poly(styrene-co-divinylbenzene) microplastic physical abrasion.

Tolerance of polar phytoplankton communities to metals.

Large amounts of pollutants reach polar regions, particularly the Arctic, impacting their communities. In this study we analyzed the toxic levels of Hg, Cd and Pb to natural phytoplankton communities of the Arctic and Southern Oceans, and compared their sensitivities with those observed on phytoplankton natural communities from temperate areas. Mercury was the most toxic metal for both Arctic and Antarctic communities, while both Cd and Pb were toxic only for the Antarctic phytoplankton. Total cell abundance of the populations forming the Arctic community increased under high Cd and Pb concentrations, probably due to a decrease of the grazing pressure or the increase of the most resistant species, although analysis of individual cells indicated that cell death was already induced at the highest levels. These results suggest that phytoplankton may have acquired adapting mechanisms to face high levels of Pb and Cd in the Arctic Ocean.

Toxic thresholds of cadmium and lead to oceanic phytoplankton: cell size and ocean basin-dependent effects.

Thresholds of cadmium (Cd) and lead (Pb) toxic to oceanic phytoplankton were examined in natural communities from the Mediterranean and Black Seas and the North East Atlantic Ocean. At concentrations of added Cd and Pb greater than 0.11 µg L(-1) , cell abundances and growth rates decreased with increasing addition of Cd and Pb, for all phytoplankton populations. The lethal concentrations at which populations decreased by half (LC50s), ranged from 0.23 to 498.7 µg L(-1) Cd for Atlantic Prochlorococcus and Black Sea picoeukaryotes, respectively, and from 20 to 465.2 µg L(-1) Pb for Mediterranean Synechococcus and Black Sea nanoplankton, respectively. These lethal concentrations were significantly lower than those previously reported for phytoplankton cultures. The LC50s were strongly related to population cell size, increasing as cell size increased, indicating that oceanic picocyanobacteria Prochlorococcus and Synechococcus populations were the most sensitive, and the largest phytoplankton cells the most resistant. Based on this relationship, differences in sensitivity to Cd across systems were detected, with Black Sea phytoplankton communities being more resistant (up to 100 times) than similar sized phytoplankton of the Mediterranean Sea and Atlantic Ocean.