Satellite tracking improves conservation outcomes for nesting hawksbill turtles in Solomon Islands

The remote tracking of endangered animals is often justified by the application of movement data to conservation problems, but examples of where scientific findings have rapidly informed conservation actions are relatively rare. In this study we satellite tracked 30 adult female hawksbill turtles (Eretmochelys imbricata) that were captured after nesting in the Arnavon Community Marine Park (ACMP), Solomon Islands. Ten hawksbill turtles were tagged in April 2016, ten in May 2017 and ten in November 2018. Our primary aim was to determine if the ACMP boundaries that were demarcated in 1995 were large enough to protect female hawksbill turtles throughout their entire nesting season. Our home range analysis revealed that collectively, tracked hawksbill turtles spent 98.5% of their inter-nesting season within the ACMP, confirming that the original park boundaries were adequate. Our first year's results were shared with community and government stakeholders and assisted in getting the ACMP declared as the Solomon Islands first national park in May 2017. Our fine scale analysis of inter-nesting habitats also highlighted that most hawksbill turtle nests were being laid on an island in the ACMP that did not have a permanent ranger presence and was experiencing persistent poaching. Based on this finding an additional ranger station was established on this uninhabited island and staffed with community rangers in 2017. Our study demonstrates how involving community, government and NGO stakeholders in applied research can lead to results being rapidly utilised to inform policy and conservation practice as soon as they become available

Electronic monitoring for improved accountability in western Pacific tuna longline fisheries

The collection of accurate fisheries catch data is critical to ensuring sustainable management of tuna fisheries, mitigating their environmental impacts and for managing transboundary fish stocks. These challenges are exemplified by the western Pacific tuna longline fishery, who's management includes >26 nations, but is informed by critically low coverage of fishing activities by scientific observers. The gap in observer data could be filled by electronic monitoring (EM), but there are few trials that span multiple nations. A large-scale trial of EM systems on tuna longliners based in Palau, Federated States of Micronesia and the Republic of the Marshall Islands, is reported on. Comparisons are made of catch rates of market and bycatch species in corresponding EM, logbook and human observer data. Retained species were under-reported in logbooks by up to three times and discards of many species were not reported in logbooks. Discards identified in the EM data included threatened species such as marine turtles. Catch rate estimates from EM data were comparable to those estimated by human observers. EM data recorded a higher species diversity of catches than logbook data. Analysis of the EM data indicated clusters of bycatch that were associated with specific fishing practices. These results suggest further expansion of EM could inform improved management of both target and bycatch species. Ultimately greater coverage of EM data could contribute to reconciling debates in international stock allocation schemes and support actions to reduce the impacts of the fishery on threatened bycatch species

Length–weight relationships to quantify biomass for motile coral reef cryptofauna

Length-weight relationships (LWRs) are a fundamental tool for the non-intrusive determination of biomass, a unit of measure that facilitates the quantification of ecosystem and fisheries productivity. LWRs have been defined and broadly applied for many marine species across a range of ecosystems, especially regarding fishes. However, LWRs are yet to be determined for the majority of marine taxa, particularly for small cryptic organisms that are difficult to census and poorly described. On coral reefs, the motile cryptofauna represent the greatest density and diversity of metazoan taxa that likely support critical steps in trophic pathways, but little empirical data exist beyond biodiversity assessments. We evaluated LWRs for 42 groups of motile cryptofauna across four microhabitats (liveAcropora, livePocillopora, dead branching coral and coral rubble) in Palau, Western Micronesia. We employed a robust methodology to determine LWRs by comparing the suitability of a series of linear, quadratic, polynomial and power models. Using the best-fit equations for each group, we provide the first documented LWRs for motile cryptofauna, namely at the level of family. LWRs were well fit (R-2 > 0.90) for 45% of the groups and reasonable (R-2 > 0.70) for 76%. The presence, size and weight of cryptofauna varied among microhabitats with the size distribution of 13 groups significantly influenced by habitat type. Establishment of these LWRs provides critical baseline information regarding an overlooked group on coral reefs, making population data on the cryptofauna more accessible to support future research aiming to characterise the roles of these taxa in ecosystem functioning and trophodynamics

From rookeries to foraging grounds:understanding regional connectivity and genetic diversity in hawksbill turtles

This study investigated the genetic structure, diversity, and migratory patterns of hawksbill turtles (Eretmochelys imbricata) from two nesting locations in Papua New Guinea (PNG) using mitochondrial DNA (mtDNA) sequencing and satellite telemetry. Tissue samples collected from nesting female hawksbill turtles (n=75) in PNG revealed a total of 6 haplotypes from the Conflict Group site and 5 haplotypes from Kavieng site, with the Conflict Group and Kavieng samples significantly differing from one another and all other known Asia-Pacific stocks. This finding expands our understanding of the genetic stock structure of hawksbill turtles in the Asia-Pacific region, resulting in 9 Management Units (MUs) now published. Satellite tracking of 15 hawksbill turtles revealed that all individuals migrated from the Conflict Group westerly towards foraging areas in eastern Australia (93%) and PNG (7%). With a mean migration path distance of 1241 ± 108 km, three distinct migration strategies were used by the 10 hawksbill turtles that made it to their foraging grounds in the I) eastern Torres Strait, II) Far North Queensland, and III) western PNG waters. A broad scope of home-range strategies and sizes (95% UD) were used, and in comparison to other studies further postulates that hawksbills are connected to non-specific foraging grounds associated with food source availability. This study provides for the first time in PNG essential insights into hawksbill turtle population structure and connectivity in the western Pacific region, highlighting the importance of effectively conserving and managing this critically endangered species as distinct population stocks. Furthermore, we make recommendations for national and regional conservation strategies and transboundary management to ensure the long-term survival and recovery of western Pacific’s hawksbill turtle populations.</p

Integrative carbonate budget model of the Great Barrier Reef

This project synthesizes and refines the carbonate budget produced for the Great Barrier Reef (GBR) in Wolfe et al. (2019). Here, we present robust methodological advances to facilitate the calculation of carbonate budgets for the GBR, including:1. The first method to quantify carbonate budgets using percent-cover data, alleviating the requirement for detailed in-situ census-based approaches to quantifying structural complexity and carbonate production (e.g., rugosity).2. Development of a carbonate budget model for the GBR that allows for site-specific conversions of coral cover to produce estimates of carbonate production.3. Inclusion of ecologically-relevant parameterisation of parrotfish bioerosion using an integrative modelling approach and GBR-specific parameter estimates.4. Explicit consideration of uncertainty surrounding production and erosion processes across spatial and temporal dimensions.5. A consequent R package (“caRbs”) for use by scientists and managers.Using the Australian Institute of Marine Science’s (AIMS) Long-Term Monitoring Program (LTMP) data on coral cover and fish biomass between 2016–2020 to parameterise the caRbs package, we quantified spatial and temporal patterns in carbonate production and bioerosion and identified the thresholds in coral cover required to maintain a positive carbonate budget for the GBR. Results highlighted the importance of Acropora sp. as the primary contributor to the carbonate budget, although massive Porites sp. were identified as key framework builders to maintain carbonate production. Carbonate production varied latitudinally, with higher calcification rates at low latitudes, while there were no clear spatial or temporal trends in primary bioerosion on the GBR. Parrotfish (Chlororus microrhinus) was the primary driver of bioerosion on fore-reef habitats. The study concluded that overall estimates of the carbonate budget on the GBR ranged between -4.9 and 28.4 kg m-2 yr-1 (~73% of sites had net positive budgets), and the threshold of coral cover to maintain a positive carbonate budget on the GBR were estimated at ~17%.Key take home messages from a management perspective are:1. For mid and outer shelf reef slope communities, overall coral cover needs to exceed 17% for reefs to have a positive carbonate budget.2. We do not yet have a corresponding threshold for inshore reefs where a number of processes, including bioerosion and biogeochemistry, can be quite different.3. The fact that an individual reef may sit below the 17% threshold does not necessarily indicate that there is a problem; it may just be in an early stage of recovery.4. The caRbs package presents an important tool to evaluate trends of reef state over time, asking how the proportion of reefs sitting below and above the 17% threshold is changing and to ask whether one region has a higher proportion of ‘positive reefs’ than another.5. A positive carbonate budget is a pre-requisite for many reef services but does not necessarily imply that all services, including accretion with sea-level rise and provision of high-quality habitat for fish and coastal protection, will occur at historical rates. Further work is needed to link carbonate budget trends explicitly to ecosystem functions. This work has started by linking carbonate budgets to reef accretion (Perry et al. 2018) but there is more to do

Knowledge Gaps in the Biology, Ecology, and Management of the Pacific Crown-of-Thorns Sea Star, Acanthaster sp., on Australia's Great Barrier Reef

Crown-of-thorns sea stars (Acanthaster sp.) are among the most studied coral reef organisms, owing to their propensity to undergo major population irruptions, which contribute to significant coral loss and reef degradation throughout the Indo-Pacific. However, there are still important knowledge gaps pertaining to the biology, ecology, and management of Acanthaster sp. Renewed efforts to advance understanding and management of Pacific crown-of-thorns sea stars (Acanthaster sp.) on Australia's Great Barrier Reef require explicit consideration of relevant and tractable knowledge gaps. Drawing on established horizon scanning methodologies, this study identified contemporary knowledge gaps by asking active and/or established crown-of-thorns sea star researchers to pose critical research questions that they believe should be addressed to improve the understanding and management of crown-of-thorns sea stars on the Great Barrier Reef. A total of 38 participants proposed 246 independent research questions, organized into 7 themes: feeding ecology, demography, distribution and abundance, predation, settlement, management, and environmental change. Questions were further assigned to 48 specific topics nested within the 7 themes. During this process, redundant questions were removed, which reduced the total number of distinct research questions to 172. Research questions posed were mostly related to themes of demography (46 questions) and management (48 questions). The dominant topics, meanwhile, were the incidence of population irruptions (16 questions), feeding ecology of larval sea stars (15 questions), effects of elevated water temperature on crown-of-thorns sea stars (13 questions), and predation on juveniles (12 questions). While the breadth of questions suggests that there is considerable research needed to improve understanding and management of crown-of-thorns sea stars on the Great Barrier Reef, the predominance of certain themes and topics suggests a major focus for new research while also providing a roadmap to guide future research efforts