Convergence of marine megafauna movement patterns in coastal and open oceans

The extent of increasing anthropogenic impacts on large marine vertebrates partly depends on the animals’ movement patterns. Effective conservation requires identification of the key drivers of movement including intrinsic properties and extrinsic constraints associated with the dynamic nature of the environments the animals inhabit. However, the relative importance of intrinsic versus extrinsic factors remains elusive. We analyze a global dataset of ∼2.8 million locations from >2,600 tracked individuals across 50 marine vertebrates evolutionarily separated by millions of years and using different locomotion modes (fly, swim, walk/paddle). Strikingly, movement patterns show a remarkable convergence, being strongly conserved across species and independent of body length and mass, despite these traits ranging over 10 orders of magnitude among the species studied. This represents a fundamental difference between marine and terrestrial vertebrates not previously identified, likely linked to the reduced costs of locomotion in water. Movement patterns were primarily explained by the interaction between species-specific traits and the habitat(s) they move through, resulting in complex movement patterns when moving close to coasts compared with more predictable patterns when moving in open oceans. This distinct difference may be associated with greater complexity within coastal microhabitats, highlighting a critical role of preferred habitat in shaping marine vertebrate global movements. Efforts to develop understanding of the characteristics of vertebrate movement should consider the habitat(s) through which they move to identify how movement patterns will alter with forecasted severe ocean changes, such as reduced Arctic sea ice cover, sea level rise, and declining oxygen content

Overhauling ocean spatial planning to improve marine megafauna conservation

Tracking data have led to evidence-based conservation of marine megafauna, but a disconnect remains between the many 1000s of individual animals that have been tracked and the use of these data in conservation and management actions. Furthermore, the focus of most conservation efforts is within Exclusive Economic Zones despite the ability of these species to move 1000s of kilometers across multiple national jurisdictions. To assist the goal of the United Nations General Assembly’s recent effort to negotiate a global treaty to conserve biodiversity on the high seas, we propose the development of a new frontier in dynamic marine spatial management. We argue that a global approach combining tracked movements of marine megafauna and human activities at-sea, and using existing and emerging technologies (e.g., through new tracking devices and big data approaches) can be applied to deliver near real-time diagnostics on existing risks and threats to mitigate global risks for marine megafauna. With technology developments over the next decade expected to catalyze the potential to survey marine animals and human activities in ever more detail and at global scales, the development of dynamic predictive tools based on near real-time tracking and environmental data will become crucial to address increasing risks. Such global tools for dynamic spatial and temporal management will, however, require extensive synoptic data updates and will be dependent on a shift to a culture of data sharing and open access. We propose a global mechanism to store and make such data available in near real-time, enabling a holistic view of space use by marine megafauna and humans that would significantly accelerate efforts to mitigate impacts and improve conservation and management of marine megafauna

The importance of sample size in marine megafauna tagging studies

Telemetry is a key, widely used tool to understand marine megafauna distribution, habitat use, behavior, and physiology; however, a critical question remains: “How many animals should be tracked to acquire meaningful data sets?” This question has wide-ranging implications including considerations of statistical power, animal ethics, logistics, and cost. While power analyses can inform sample sizes needed for statistical significance, they require some initial data inputs that are often unavailable. To inform the planning of telemetry and biologging studies of marine megafauna where few or no data are available or where resources are limited, we reviewed the types of information that have been obtained in previously published studies using different sample sizes. We considered sample sizes from one to >100 individuals and synthesized empirical findings, detailing the information that can be gathered with increasing sample sizes. We complement this review with simulations, using real data, to show the impact of sample size when trying to address various research questions in movement ecology of marine megafauna. We also highlight the value of collaborative, synthetic studies to enhance sample sizes and broaden the range, scale, and scope of questions that can be answered

A standardisation framework for bio-logging data to advance ecological research and conservation

1. Bio-logging data obtained by tagging animals are key to addressing global conservation challenges. However, the many thousands of existing bio-logging datasets are not easily discoverable, universally comparable, nor readily accessible through existing repositories and across platforms, slowing down ecological research and effective management. A set of universal standards is needed to ensure discoverability, interoperability and effective translation of bio-logging data into research and management recommendations. 2. We propose a standardisation framework adhering to existing data principles (FAIR: Findable, Accessible, Interoperable and Reusable; and TRUST: Transparency, Responsibility, User focus, Sustainability and Technology) and involving the use of simple templates to create a data flow from manufacturers and researchers to compliant repositories, where automated procedures should be in place to prepare data availability into four standardised levels: (a) decoded raw data, (b) curated data, (c) interpolated data and (d) gridded data. Our framework allows for integration of simple tabular arrays (e.g. csv files) and creation of sharable and interoperable network Common Data Form (netCDF) files containing all the needed information for accuracy-of-use, rightful attribution (ensuring data providers keep ownership through the entire process) and data preservation security. 3. We show the standardisation benefits for all stakeholders involved, and illustrate the application of our framework by focusing on marine animals and by providing examples of the workflow across all data levels, including filled templates and code to process data between levels, as well as templates to prepare netCDF files ready for sharing. 4. Adoption of our framework will facilitate collection of Essential Ocean Variables (EOVs) in support of the Global Ocean Observing System (GOOS) and intergovernmental assessments (e.g. the World Ocean Assessment), and will provide a starting point for broader efforts to establish interoperable bio-logging data formats across all fields in animal ecology

Enhanced monitoring of life in the sea is a critical component of conservation management and sustainable economic growth

Marine biodiversity is a fundamental characteristic of our planet that depends on and influences climate, water quality, and many ocean state variables. It is also at the core of ecosystem services that can make or break economic development in any region. Our purpose is to highlight the need for marine biological observations to inform science and conservation management and to support the blue economy. We provide ten recommendations, applicable now, to measure and forecast biological Essential Ocean Variables (EOVs) as part of economic monitoring efforts. The UN Decade of Ocean Science for Sustainable Development (2021–2030) provides a timely opportunity to implement these recommendations to benefit humanity and enable the USD 3 trillion global ocean economy expected by 2030

Water temperature is a key driver of horizontal and vertical movements of an ocean giant, the whale shark Rhincodon typus

Integrated analysis of the vertical and horizontal movements of epipelagic fishes requires high-resolution data from tags that have been attached to animals for long periods. The recovery of a SPLASH tag deployed on a whale shark Rhincodon typus for 3 mo enabled access to archival data of horizontal and vertical movements of the shark that travelled 5380 km from Christmas Island to the Banda Sea. We examined water temperature and bathymetry to compare movements of the shark with key oceanographic features. Over 89 d, we identified 1931 dives and grouped these into 5 broad categories depending on dive shape. To investigate the potential for these dives to reflect behavioural thermoregulation, we used boosted regression trees to model the relationship between pre- and post-dive surface durations and dive characteristics. The movements of the shark were correlated with water temperatures, with the animal following frontal systems while remaining in a sea surface temperature (SST) range of 24-29°C. Across the continental shelf off north-western Australia, the shark mostly remained near the seafloor, likely avoiding very warm SSTs and strong currents at the surface. U- (foraging) and V- (searching) shaped dives accounted for ~78% of dives. Foraging dives during the day descended to 200-500 m and were preceded and followed by extended periods at the surface, whereas at night, the shark rarely dived below 200 m, likely foraging near the thermocline. Our results show how water temperatures influence the movement of this whale shark, with ‘basking’ at the surface during the day likely to gather environmental heat for thermoregulation, aiding to maintain body temperatures.</jats:p