Occurrence of tar balls on the beaches of Fernando de Noronha Island, South Equatorial Atlantic

A comprehensive review of oil residues in the world oceans: types, characteristics, sources and distribution

The increasing industrialization and extensive utilization of petroleum products, resulting in the emergence of its residues, contribute to the formation of tar. Their accumulation is strongly influenced by environmental factors, including winds, currents, and coastal geomorphology. This review explores the physical characteristics and primary sources of tar residues, with particular focus on tanker operations and oil spill incidents. It further synthesizes the existing literature, focusing on regional tar surveys in the North Atlantic, Pacific and Indian Oceans, the Mediterranean Sea and the Arabian Gulf, aiming to consolidate current knowledge and compare regional tar concentrations. Global assessments of tar concentrations reveal notable spatial variability, with the Mediterranean Sea exhibiting the highest concentration, followed by the Arabian Gulf and the Caribbean Sea. Lower concentrations were recorded in the Pacific's Bering Sea and Gulf of Alaska areas characterized by limited shipping activity. However, non-standardized sampling strategies, inconsistencies in tow techniques, and irregular tar surveys introduce considerable uncertainty in assessing the distribution of tar residues. Significant gaps are identified in quantitative and qualitative assessments and source identification, resulting in systematic documentation of coastal tar concentrations. Despite regulatory advancements including the implementation of MARPOL Annex I, and technological improvements like segregated ballast systems, tar pollution remains a global concern. The review also highlights the urgent need for long-term monitoring, standardized methodologies, and improved risk assessment to inform effective management, particularly in tourism-dependent coastal regions.

Fecundity of the snapping shrimp Alpheus estuariensis (Caridea: Alpheidae) after the oil spill in three mangroves of tropical Brazil

This study examined the impacts of oil spills since 2019 by analyzing polycyclic aromatic hydrocarbons (PAHs) in sediments and their effects on the fecundity of the shrimp Alpheus estuariensis. Samples were collected from mangroves in three Pernambuco locations: Catuama, Suape Bay, and Carneiros Beach. Ovigerous females were identified, and their eggs were counted and classified by embryonic stage. Sediment PAH levels were analyzed in freeze-dried and homogenized samples. A total of 107 females were analyzed, with varying distributions across sites. In the dry season, Carneiros showed the highest average fecundity (309 eggs), followed by Suape (238) and Catuama (154), without statistical differences. During the rainy season, Carneiros had significantly higher fecundity (605 eggs) compared to Catuama (176) and Suape (173). PAH concentrations were highest at Catuama (79 ng g-1), followed by Suape (72 ng g-1), and Carneiros (19 ng g-1). Fecundity was inversely related to PAH levels, with Carneiros showing the highest fecundity and lowest PAHs. Four years post-spill, high- molecular- weight PAHs (4-6 rings) were prevalent, posing carcinogenic and mutagenic risks. Diagnostic ratios indicated that PAHs primarily originated from pyrolytic processes, particularly combustion, highlighting biomass burning as a significant source. These findings emphasize the necessity for ongoing monitoring of impacted areas using model species to understand long-term environmental impacts on Brazil's northeastern coast.

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.

Levels, source appointment, and ecological risk of petroleum hydrocarbons in tropical coastal ecosystems (northeast Brazil): Baseline for future monitoring programmes of an oil spill area

We reviewed 20 years of levels, sources, and environmental risks related to the main petroleum hydrocarbons in the northeast region of Brazil. The aim of this study was to conduct a systematic review to serve as a comprehensive baseline for future monitoring programmes related to the oil spill disaster in 2019/2020. Most contamination levels of both PAHs and AHs were classified as low, except those in specific areas influenced by human activities, such as ports, highly urbanised mangroves, or rivers of medium-sized cities with inadequate liquid and solid waste treatment. Most hydrocarbons were linked to natural sources and burning processes, except in regions of extraction activities and petrochemical facilities as well as highly urbanised areas, where degraded petroleum and oil hydrocarbons predominated. Only 2.5% of the samples exceeded threshold effect levels for ∑_16-PAHs and no samples exceeded probable effect levels. When regional threshold levels were used, however, the probable effect for the ∑_16-PAHs measured was high, ranging from 5.8 to 6.1%. The few studies reporting biological responses showed that hydrocarbons from anthropogenic sources can induce adverse effects on marine organisms even at low to moderate levels. As the region has recently received a considerable quantity of crude oil, studies should be prioritised for a more precise assessment of the impact of this oil spill.