The role of habitat heterogeneity and timescales on the recovery of reef epifaunal communities affected by a massive oil spill in the tropics.

From August 2019 to January 2020 the Brazilian Coast was impacted by the largest oil spill in the Tropical oceans ever since. Paiva Beach, one of the most preserved sandy beaches in the northeast tropical Brazilian coast, was among the most affected regions by the oil spill in October 2019. This area has important reef systems that harbor abundant macroalgal assemblages with very diverse epifaunal communities. The present study aims to evaluate the impacts of the 2019 oil spill on epifauna associated with the seaweed species Jania capillacea and Penicillus capitatus collected in Paiva Beach from July 2019 to October 2022, and use the interaction macroalgae/epifauna/timescale as a proxy to quantify the effects of oil spills on communities structure and recovery. The epifauna of both algae did not suffer severe changes in abundance immediately after the spill, however, the abundance of taxa like echinoderms, sea spiders (Pycnogonida) and peracarid crustaceans dropped during or soon after the event, whereas others, like sabellid worms, had strong increase in abundance, possibly related to the spill. Both phytal assemblages also had distinct temporal patterns in species diversity and abundance, the last being strongly correlated to amphipod abundance for some taxa. The epifauna of J. capillacea had a short-term tendency of decrease in taxonomic diversity, whereas the epifaunal communities of P. capitatus gained a few taxa in the months immediately after the disaster. The diversity profiles of both communities returned to pre-spill conditions a few months later, with a slower abundance recovery in J. capillacea. Local environmental characteristics like landscape heterogeneity, connectivity with other environments, and critical-species (mainly amphipods) were possibly the main buffering factors for the phytal communities after the oil spill.

Tar balls as a floating substrate for long-distance species dispersal.

Recent arrivals of tar balls have been observed in several tropical beaches associated with the oceanic circulation that flows to the Brazilian continental shelf. Between August and September 2022, tar balls were collected in the northeastern coast of Brazil and analyzed. Nearly 90 % of the oils were colonized by barnacles, polychaetes, decapods, and algae. Most rafting organisms were Lepas anserifera with capitulum measuring 0.32 to 22.21 mm. Based on the growth rate of barnacles and the speed of the SEC it was estimated that tar balls were floating since July and August 2022 and traveled a maximum of 1938.82 km. The organisms and tar balls' possible origin is in the international waters, near to the meso-Atlantic ridge, known for oil tanker traffic. The tar balls, in addition to the oil-related impacts, can act as a vector of long-distance species dispersion, and it needs to raise an alert, considering the possible ecological impacts.

Effects of contact with crude oil and its ingestion by the symbiotic polychaete Branchiosyllis living in sponges (Cinachyrella sp.) following the 2019 oil spill on the tropical coast of Brazil.

In August 2019, thousands of tons of crude oil from an unidentified source began washing up on the Brazilian coast, causing the most severe environmental disaster that has ever impacted the South Atlantic Ocean. Paiva beach, which has some of the best-preserved tropical coral reefs on the Brazilian coast, was one of the coastal environments most severely affected by this oil. We report on the impact of the disaster on the local population of the symbiotic polychaete Branchiosyllis spp. associated with the sponge Cinachyrella sp. Following the oil spill sponges were found with oil stains on their surface and in their channels, and oil droplets were identified among the grains of the sediment accumulated within these channels. During this same period, the polychaetes in sponges had oil droplets on the surface of the body or in their pharynxes. Solubility tests using mineral oil and Raman spectra indicated that these oil droplets, found in both the sponges and the polychaetes, had similar chemical characteristics to those of the crude oil that washed up on the beach. Following the disaster, the abundance of Branchiosyllis declined sharply, although there was no significant shift in the mean size of individuals. By December 2019, the density of polychaetes was significantly lower than in the preceding months (107.9 ± 28.31 ind.10 mL-1 of sponge in August 2019 vs. 18.62 ± 35.48 ind.10 mL-1 of sponge in December 2019). This abrupt reduction in abundance with no change in the mean size of the individuals indicates that mortality affected all size (age) classes similarly, which is typical of anthropogenic impacts rather than natural mortality. It is thus clear that the contamination of polychaetes with crude oil increased mortality, causing a significant reduction in the Branchiosyllis populations of the coral reefs of Paiva beach following the 2019 oil spill.

Immediate effects of the 2019 oil spill on the macrobenthic fauna associated with macroalgae on the tropical coast of Brazil.

The 2019-2020 Brazil oil spill disaster affected several ecosystems and species-rich areas. The shallow-water reefs of Paiva beach are among the best-preserved coastal environments in the State of Pernambuco (NE Brazil), but were severely affected by oil arrival at the end of 2019. The reefs are densely covered by macroalgae as important biogenic substrates for benthic fauna. Based on that, herein, we provide a baseline assessment of the immediate impacts of the oil spill on the structure of epifaunal communities associated with the algae Jania capillacea and Penicillus capitatus. The benthic communities in both algae simplified (reduction of species richness and abundance) soon after oil arrival, while opportunistic taxa increased. After two months, the macrofaunal communities restructured to almost pre-disaster levels. However, polychaeta diversity remained low. Despite the apparently fast recovery of reef macrobenthos, a more detailed, long-term monitoring is necessary to evaluate the chronic effects.