Impacts of a shallow shipwreck on a coral reef: A case study from St. Brandon's Atoll, Mauritius, Indian Ocean

Microplastics in coral from three Mascarene Islands, Western Indian Ocean

Little is known about microplastics (MPs) in corals from the Indian Ocean. We compared MP concentrations, morphotypes, size, colours, and polymer compositions in six coral genera from three remote Mascarene islands (Rodrigues, St. Brandon's Atoll, and Agalega) of the Republic of Mauritius, on a 1200 km transect located in the South Equatorial Current (SEC). The mean MP concentration was 0.78 n/g (53 % fibres) with no significant differences between islands. Polymers were polypropylene (78 %) and polyethylene (18 %). We conclude that the SEC's MP concentrations and compositions have homogenized over thousands of kilometres across the Indian Ocean. We discuss the lack of hazardous polyurethane MPs in coral samples given obvious sources on St Brandon. To the best of our knowledge, this study is the first to report on MPs in coral from the Western Indian Ocean and the Mascarene Islands providing a baseline for further research, monitoring, mitigation, and policy development.

Shipwreck ecology: Understanding the function and processes from microbes to megafauna

An estimated three million shipwrecks exist worldwide and are recognized as cultural resources and foci of archaeological investigations. Shipwrecks also support ecological resources by providing underwater habitats that can be colonized by diverse organisms ranging from microbes to megafauna. In the present article, we review the emerging ecological subdiscipline of shipwreck ecology, which aims to understand ecological functions and processes that occur on shipwrecks. We synthesize how shipwrecks create habitat for biota across multiple trophic levels and then describe how fundamental ecological functions and processes, including succession, zonation, connectivity, energy flow, disturbance, and habitat degradation, manifest on shipwrecks. We highlight future directions in shipwreck ecology that are ripe for exploration, placing a particular emphasis on how shipwrecks may serve as experimental networks to address long-standing ecological questions.

In the aftermath of Hurricane Irma: Colonization of a 4-year-old shipwreck by native and non-native corals, including a new cryptogenic species for the Caribbean

Little is known about early coral settlement on shipwrecks with regard to their species and size compositions. Hurricanes in the Caribbean have a long history of sinking ships but a link with new coral settlement is understudied. In 2017, Hurricane Irma caused the sinking of over 300 vessels in the coastal waters of Saint Martin, eastern Caribbean. In 2021, coral settlement was studied on one of them, which included two native, one non-native, and two cryptogenic species. The corals were smaller than 8 cm in diameter. The invasive Tubastraea coccinea was the most abundant scleractinian and was predominantly represented by juveniles. A cryptogenic species, Stragulum bicolor, new for the Caribbean, was the most common octocoral. Because they can be harmful to the environment, shipwrecks should be monitored frequently for the occurrence of non-native species, especially when they are only a few years old.

Metals and co-presence of other pollutants in mussels (Perna perna) around Algoa Bay: Human consumption safety concerns

Elevated metal concentrations can become harmful to marine organisms and to humans that consume them. Metal concentrations at multiple sites around Algoa Bay, South Africa, were last investigated in the 1980s. We collected wild brown mussels (Perna perna) from seven sites around Algoa Bay, and quantified metallic elements using ICPMS. Metallic element concentrations differed significantly among the sampling sites and correlated with pollution sources at specific sites. The concentration of Pb in mussels at one site slightly exceeded South African limits. Based on the South African estimated daily intake, the target hazard quotient, and South African metal limits, mussels from Algoa Bay are safe for human consumption, except possibly from one site. However, combined with data on bisphenols and benzophenone UV filters in P. perna from the same sites, we suggest a possible health concern to consumers.

Contingency planning for coral reefs in the Anthropocene; The potential of reef safe havens

Reducing the global reliance on fossil fuels is essential to ensure the long-term survival of coral reefs, but until this happens, alternative tools are required to safeguard their future. One emerging tool is to locate areas where corals are surviving well despite the changing climate. Such locations include refuges, refugia, hotspots of resilience, bright spots, contemporary near-pristine reefs, and hope spots that are collectively named reef 'safe havens' in this mini-review. Safe havens have intrinsic value for reefs through services such as environmental buffering, maintaining near-pristine reef conditions, or housing corals naturally adapted to future environmental conditions. Spatial and temporal variance in physicochemical conditions and exposure to stress however preclude certainty over the ubiquitous long-term capacity of reef safe havens to maintain protective service provision. To effectively integrate reef safe havens into proactive reef management and contingency planning for climate change scenarios, thus requires an understanding of their differences, potential values, and predispositions to stress. To this purpose, I provide a high-level review on the defining characteristics of different coral reef safe havens, how they are being utilised in proactive reef management and what risk and susceptibilities they inherently have. The mini-review concludes with an outline of the potential for reef safe haven habitats to support contingency planning of coral reefs under an uncertain future from intensifying climate change.

Paint particles in the marine environment: An overlooked component of microplastics

Because paint particles consist of a resin (polymer) combined with one or more additives, they bear compositional similarities with microplastics. Despite these shared characteristics, however, paint particles are often undetected, deliberately overlooked or evade classification in the pool of micro-debris (all synthetic debris of < 5 mm in size), and in particular in the marine setting where an extensive body of microplastic literature exists. Accordingly, the present paper provides a critical insight into the physico-chemical properties, sources, distributions, behaviour and toxicity of paint particles in the marine environment. Paint particles contain a greater proportion of additives than plastics and, consequently, are more brittle, angular, opaque, dense, heterogeneous and layered than microplastics of equivalent dimensions. Land-based sources of paint particles, including deteriorating or disturbed coatings on roads and building, are transported to the ocean with other microplastics via urban runoff, water treatment facilities and the atmosphere. However, inputs of paint particles are enhanced significantly and more directly by the disturbance, erosion and weathering of coatings on coastal structures, boats and ships. Estimates of paint particle emissions to the marine environment vary widely, with calculated contributions to the total synthetic micro-debris input as high as 35%. Upper estimates are consistent with available (albeit limited) quantitative information on the relative abundance of paint particles amongst synthetic material captured by sea surface trawls and ingested by marine animals. Of greatest environmental concern is the high chemical toxicity of paint particles compared with similarly-sized microplastics and other synthetic debris. This results from the contemporary and historical use of high concentrations of hazardous inorganic additives in marine antifouling and land-based paints, and the relatively ready mobilisation of harmful ions, like Cu+/Cu2+, TBT+, Pb2+ and CrO4 2-, from the matrix. Recommendations arising from this review include greater use of particulate capturing devices, waste collection systems and recycling facilities during paint disturbance, raising awareness of the potential impacts of discarded paint amongst users, and alerting the microplastic community to the significance of paint particles and developing means by which they are isolated from environmental samples.

Persistent organic pollutants in sea bird eggs from the Indian Ocean's Mascarene Basin

We report the concentrations of persistent organic pollutants (POPs) in seabird eggs from St. Brandon's Atoll, a tropical island system in the western Indian Ocean. Ten eggs each of sooty terns (Onychoprion fuscatus), fairy terns (Gygis alba), and common noddies (Anous stolidus) were collected from the atoll. For a terrestrial reference, we analysed three feral chicken (Gallus gallus domesticus) eggs from the same location. Sooty tern eggs contained the highest mean concentrations of three chemical classes: ƩCHL₃ (0.21 ng/g wm; wet mass), ƩPCB₁₀ (1.5 ng/g wm), and ƩPBDE₆ (1.1 ng/g wm). Fairy tern eggs contained the highest mean concentrations of HCB (0.68 ng/g wm) and ƩCHB₅ (0.83 ng/g wm). The chicken eggs contained the highest mean concentrations of ƩDDT₃ (2.6 ng/g wm), while common noddy eggs contained the highest mean concentrations of ƩHCH₂ (0.5 ng/g wm). We surmise that the differences in chemical composition between species reflect different pollutant compositions in prey from the bird's different foraging ranges. The sooty terns foraging offshore contained higher POPs concentrations than the nearshore-foraging common noddies. Fairy tern eggs contained intermediate concentrations, commensurate with their intermediate foraging. Inter-island differences in contaminant concentrations were seen between eggs of the common noddies from St. Brandon's Atoll and Rodrigues Island, 520 km to the south-east. Concentrations of contaminants found in this study were lower than values quantified by other studies, making St. Brandon's Atoll an ideal reference site to monitor background concentrations of POPs in the tropical Indian Ocean.

Chlorinated and brominated persistent compounds in hard coral, soft coral, and parrotfish from remote Mascarene islands

Persistent halogenated compounds (PHC) are of concern for human and environmental health. Persistent Organic Pollutants (POPs) are regulated by international treaties, but alternative compounds such as novel brominated flame retardants (NBFRs) and Dechlorane Plus (DP) are not-yet they are increasingly used. There are no data on PHCs in coral reef biota from tropical islands in the western Indian Ocean (WIO). For this assessment, three hard coral genera, two soft coral genera, and ember parrotfish (Scarus rubroviolaceus) were collected from the remote Rodrigues, Agalega, and St. Brandon's Atoll (Republic of Mauritius) in the Mascarene Basin of the WIO. Five compounds - Pentabromotoluene (PBT), γ-HCH, p,p'-DDE, HCB, and BDE-47- were quantifiable in all samples. Hard coral consistently contained the lowest concentrations of PHCs, except for NBFRs. The presence of BDE-47 suggests long-range aerial transport. We quantified DP, currently a candidate POP, in coral reef biota. PBT was measured in all samples also suggests long-range transport. Because the hard coral, soft coral, and fish had differing concentrations and patterns of PHCs, future surveys should stratify sampling accordingly. Agalega and St. Brandon's Atoll can be considered as locations to monitor changes in background concentrations of pollutants due to their remoteness.

Paint fragments as polluting microplastics: A brief review

Paint particles are part of the increasingly important microplastics (MPs) pollution of our oceans. They contain polyurethanes, polyesters, polyacrylates, polystyrenes, alkyls and epoxies. In spite of their prevalence, paint fragments are often excluded from MP audits. This review, citing 127 references, discusses detection, characteristics, sources and ecological effects of paint fragments in our oceans, as well as the abundance of paint fragments in MP samples around the world and their colonization by marine microorganisms, which differs from that of non-paint MPs. Paint MPs arise from shipping and boating activities, road markings and external surfaces of buildings. Many paint fragments come from antifouling paints used on commercial vessels and leisure boats; these may be regarded as particular pollutants, not only containing but also leaching heavy metals and biocides. Some effects of antifouling paint particles on aquatic biota are caused by these toxins. Paint particles are an understudied portion of marine MP pollution.

Perfluoroalkyl substances (PFAS) in tern eggs from St. Brandon's Atoll, Indian Ocean

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic fluorinated compounds of concern for human and environmental health. There is no data on PFAS concentrations in marine bird eggs from the Western Indian Ocean. We analysed eight PFAS in eggs of fairy terns (Gygis alba), sooty terns (Onychoprion fuscatus), and common noddies (Anous stolidus) from St. Brandon's Atoll. Fairy tern eggs contained the highest concentrations, followed by sooty terns and common noddies. Perfluoroundecanoic acid (PFUdA) had the highest mean concentration (2.3 ng/g wm), followed by perfluorooctane sulfonic acid (PFOS) (2.0 ng/g wm), and perfluorononanoic acid (PFNA) (0.93 ng/g wm) in fairy tern eggs. Concentrations of all PFAS were lower than values found in literature. PFOS and PFOA concentrations were three orders of magnitude lower than toxicity reference values and levels of lowest-observed-adverse-effect-level concentrations. Eggs from St. Brandon's would be useful to monitor background changes on a regional and perhaps global scale.