From little things big things grow: enhancement of an acoustic telemetry network to monitor broad-scale movements of marine species along Australia's east coast.

BACKGROUND: Acoustic telemetry has become a fundamental tool to monitor the movement of aquatic species. Advances in technology, in particular the development of batteries with lives of > 10 years, have increased our ability to track the long-term movement patterns of many species. However, logistics and financial constraints often dictate the locations and deployment duration of acoustic receivers. Consequently, there is often a compromise between optimal array design and affordability. Such constraints can hinder the ability to track marine animals over large spatial and temporal scales. Continental-scale receiver networks have increased the ability to study large-scale movements, but significant gaps in coverage often remain. METHODS: Since 2007, the Integrated Marine Observing System's Animal Tracking Facility (IMOS ATF) has maintained permanent receiver installations on the eastern Australian seaboard. In this study, we present the recent enhancement of the IMOS ATF acoustic tracking infrastructure in Queensland to collect data on large-scale movements of marine species in the northeast extent of the national array. Securing a relatively small initial investment for expanding receiver deployment and tagging activities in Queensland served as a catalyst, bringing together a diverse group of stakeholders (research institutes, universities, government departments, port corporations, industries, Indigenous ranger groups and tourism operators) to create an extensive collaborative network that could sustain the extended receiver coverage into the future. To fill gaps between existing installations and maximise the monitoring footprint, the new initiative has an atypical design, deploying many single receivers spread across 2,100 km of Queensland waters. RESULTS: The approach revealed previously unknown broad-scale movements for some species and highlights that clusters of receivers are not always required to enhance data collection. However, array designs using predominantly single receiver deployments are more vulnerable to data gaps when receivers are lost or fail, and therefore "redundancy" is a critical consideration when designing this type of array. CONCLUSION: Initial results suggest that our array enhancement, if sustained over many years, will uncover a range of previously unknown movements that will assist in addressing ecological, fisheries, and conservation questions for multiple species.

Towards the Development of Standardized Bioassays for Corals: Acute Toxicity of the UV Filter Benzophenone-3 to Scleractinian Coral Larvae.

Coral reefs have been declining globally at a historically unprecedented rate. Ultraviolet (UV) filters used in sunscreens may contribute to this decline at local scales, which has already led to bans on various organic UV filters in some regions. However, the underlying studies for these bans demonstrated significant flaws in the experimental design due to a lack of validated and standardized testing methods for corals. This study aimed to investigate options for the development of a standard acute toxicity test for the larval stage of scleractinian corals. Planula larvae of two brooding (Leptastrea purpurea and Tubastraea faulkneri) and two spawning (Acropora digitifera and A. millepora) species were exposed to the organic UV filter benzophenone-3 (BP3) for 48 h under static conditions. We observed interspecific variations in toxicity, with A. digitifera being the most sensitive (LC50 = 0.75 µg L-1) and T. faulkneri the least sensitive (LC50 = 2951.24 µg L-1) species. Inhibition of settlement was found to be a useful endpoint leading to an EC50 of 1.84 µg L-1 in L. purpurea larvae. Although the analytical challenges of measuring lipophilic substances in small volume test setups remain, the here applied test design and selected endpoints are suitable for further validation and subsequent standardization.

Reef-building corals act as long-term sink for microplastic.

The pollution of the marine environment with microplastics is pervasive. However, microplastic concentrations in the seawater are lower than the number of particles entering the oceans, suggesting that plastic particles accumulate in environmental sinks. Yet, the exact long-term sinks related to the "missing plastic" phenomenon are barely explored. Sediments in nearshore biogenic habitats are known to trap large amounts of microplastics, but also the three-dimensional structures of coral reefs might serve as unique, living long-term sinks. The main framework builders, reef-building corals, have been shown to ingest and overgrow microplastics, potentially leading to a deposition of particles in reef structures. However, little is known about the number of deposited particles and the underlying processes determining the permanent deposition in the coral skeletons. To test whether corals may act as living long-term sink for microplastic, we exposed four reef-building coral species to polyethylene microplastics (200 particles L-1 ) in an 18-month laboratory experiment. We found microplastics in all treatment specimens, with low numbers of particles trapped in the coral tissue (up to 2 particles per cm2 ) and much higher numbers in the skeleton (up to 84 particles per cm3 ). The numbers of particles accumulated in the coral skeletons were mainly related to coral growth (i.e., skeletal growth in volume), suggesting that deposition is a regularly occurring stochastic process. We estimate that reef-building corals may remove 0.09%-2.82% of the bioavailable microplastics from tropical shallow-reef waters per year. Our study shows for the first time that microplastic particles accumulate permanently in a biological sink, helping to explain the "missing plastic" phenomenon. This highlights the importance of coral reefs for the ecological balance of the oceans and reinforces the need to protect them, not only to mitigate the effects of climate change but also to preserve their ecosystem services as long-term sink for microplastic.

UV filters used in sunscreens-A lack in current coral protection?

Ultraviolet (UV) filters used in sunscreens are among the anthropogenic substances that may enter the marine environment by both indirect (via wastewater) and direct pathways (leisure activities). Owing to the recent global decline in coral population, the impact of those UV filters on the coral health is currently under increased investigation. First results from scientists suggest that some of the filters may be toxic to various coral life stages, but an initial cross comparison with existing data from other freshwater organisms does not indicate that corals are specifically more susceptible to UV filters than other standard species. In fact, the available data leading to this conclusion is still vague and based on toxicity and bioaccumulation tests with corals, which are both still at the research stage. To facilitate a proper hazard assessment, robust experimental procedures for coral ecotoxicological studies are considered mandatory. In other words, additional steps should be taken to standardize and validate such new test systems to generate reliable results, which then can be used in regulatory decision making. Furthermore, to facilitate a more detailed and site-specific environmental risk assessment in the marine area, an application-based exposure scenario must be developed. Until these data and tools become available, environmental hazard and risk assessments may be carried out using existing data from freshwater organisms and existing tonnage-based exposure scenarios as a potential surrogate. Integr Environ Assess Manag 2021;17:926-939. © 2021 SETAC.