Larval fish assemblages of the coastal area affected by the tailings of the collapsed dam in southeast Brazil

In November 2015, the Fundão dam collapsed releasing metal-rich mud into the environment. Our goal was to identify the larval fish present in samples collected from the marine area that was affected by the polluted mud. Sampling stations were distributed in four areas from south of Bahia to south of Espírito Santo states, Brazil. Larval fish were sampled in January/February and April 2016 using bongo (330 and 500 μm) and neustonic (500 μm) nets. A total of 4,182 larval fish were identified comprising 52 families and 75 species. Clupeidae, Engraulidae, Chloroscombrus chrysurus, Gerreidae, Eucinostomus spp., Labridae and Gobiidae were the most frequent taxa. Five families contributed to more than 20% each, of the total larval fish identified in at least one area or sampling period. The similarity analysis showed the differences between the larval fish assemblages among the four sampling areas, with the exceptions of south versus the mouth of the Doce River and north I versus north II. The larval fish assemblages were dominated by larvae in the preflexion stage representing more than 50% of the total individuals identified in each area. A total of 10% of the larval fish that were identified in front of the mouth of the Doce River, in January/April, had reddish sediment adhered to their bodies and comprised Stellifer spp., Chloroscombrus chrysurus, and Trinectes paulistanus. The digestive tracts of some Chloroscombrus chrysurus and Monacanthus ciliatus larvae, collected in April, were damaged. The analysis, which was conducted with specimens of both species showed that they had significantly higher heavy metals concentrations than the results obtained from larvae without damage, collected at the same time, and larvae obtained before the accident. These results confirm the influence of the mud plume on larval fish assemblages of this area and reinforce the need to continue monitoring these organisms.