Florida Aquarium

ABSTRACTSeamounts and offshore islands support unique assemblages of sharks. The aim of this study was to contribute to the limited knowledge of how co‐existing shark species partition spatial resources at these remote bathymetric features, particularly those influenced by a mix of temperate and tropical oceanographic conditions, as well as human activities. The space use of 34 dusky (Carcharhinus obscurus), 32 Galapagos (C. galapagensis), 47 tiger (Galeocerdo cuvier), and 20 sandbar (C. plumbeus) sharks was monitored with acoustic telemetry between 2021 and 2024 in coastal waters around Norfolk Island, Australia, a remote island in the southwestern Pacific Ocean. Seasonal patterns of residency and fine‐scale site fidelity were compared across species during this multi‐year study. Tiger sharks, consisting primarily of mature females, were seasonally present at Norfolk Island with peak residency during the Austral summer (November to April). A similar pattern existed for juvenile sandbar sharks, although departures from the island were not as common. Both species rarely overlapped in space with each other or resident (year‐round) juvenile dusky and Galapagos sharks, which were often detected in shallow waters at boating/fishing piers where incidental feeding readily occurs. Tiger sharks also showed a strong affinity to a specific area on the west side of the island where organic waste (livestock) disposal into the ocean has been ongoing for several decades. Nearshore areas of Norfolk Island support mature and immature sharks in unique ways, and human activities may further influence the space use of these species. The consistent use of specific areas around Norfolk Island across species highlights the importance of offshore islands as hotspot areas fulfilling basic biological needs at both local and oceanic scales.

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Climate change is shifting animal distributions. However, the extent to which future global habitats of threatened marine megafauna will overlap existing human threats remains unresolved. Here we use global climate models and habitat suitability estimated from long-term satellite-tracking data of the world’s largest fish, the whale shark, to show that redistributions of present-day habitats are projected to increase the species’ co-occurrence with global shipping. Our model projects core habitat area losses of >50% within some national waters by 2100, with geographic shifts of over 1,000 km (∼12 km yr−1). Greater habitat suitability is predicted in current range-edge areas, increasing the co-occurrence of sharks with large ships. This future increase was ∼15,000 times greater under high emissions compared with a sustainable development scenario. Results demonstrate that climate-induced global species redistributions that increase exposure to direct sources of mortality are possible, emphasizing the need for quantitative climate-threat predictions in conservation assessments of endangered marine megafauna.

Animals under managed care in zoos and aquariums are ideal surrogate study subjects for endangered species that are difficult to obtain in the wild. We compared the fecal and oral microbiomes of healthy, managed African penguins (Spheniscus demersus) to those of other domestic and wild vertebrate hosts to determine how host identity, diet, and environment shape the penguin microbiome. The African penguin oral microbiome was more similar to that of piscivorous marine mammals, suggesting that diet and a marine environment together play a strong role in shaping the oral microbiome. Conversely, the penguin cloaca/fecal microbiome was more similar to that of other birds, suggesting that host phylogeny plays a significant role in shaping the gut microbiome. Although the penguins were born under managed care, they had a gut microbiome more similar to that of wild bird species compared to domesticated (factory-farmed) birds, suggesting that the managed care environment and diet resemble those experienced by wild birds. Finally, the microbiome composition at external body sites was broadly similar to that of the habitat, suggesting sharing of microbes between animals and their environment. Future studies should link these results to microbial functional capacity and host health, which will help inform conservation efforts.

The authors declare that there are no conflicts of interest associated with this publication. The data that support the findings of this study are openly available in National Center for Biotechnology Information at https://www.ncbi.nlm.nih.gov/, reference number MN432490, MT926123. Figure S1 Histologic appearance of a typical infected Banggai cardinalfish from the BCIV-2010 case. (a) and (b) Spleen: Basophilic inclusion bodies in megalocytic cells whose morphology is often obscured. Foci of necrosis within intervening pulp areas. (c) and (d) Kidney: Basophilic inclusion bodies in megalocytic cells within foci of interstitial haematopoietic necrosis. (e) and (f) Intestine: Basophilic inclusion bodies in megalocytic perivascular cells but minimal mucosal reaction. Pigmentation within normal limits. Original magnifications: (a, c) 100×, (d, e) 200×, (b, f) 400×; H&E stain. Figure S2 Conventional PCR results of the Banggai cardinalfish case from 2000 (BCIV-2000) using the MCV-F/R primers (Koda et al., 2018) and a 100 bp ladder. (a) a single positive band for BCIV-2000 at the 173 bp position. Samples (b) and (c) are negative and correspond to the extraction control and negative template control, respectively. (d) a single bright band at the 173 bp position, representing the positive control for the MCV assay. Table S1 Genome annotation of the Banggai cardinalfish iridovirus from 2012 (BCIV-2012). Table S2 Genome annotation of the Banggai cardinalfish iridovirus from 2017 (BCIV-2017). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Slow or nonexistent natural recovery of the Caribbean long-spined sea urchin (Diadema antillarum) following a mass mortality event in 1983–1984 has prompted interest in hatchery-origin production and restocking to aid coral-reef restoration. A critical first step is the ability to propagate D. antillarum from gametes, at scale. However, a unique larval biology and difficult and lengthy culture period of ~ 40 days has resulted in inconsistent success over the past 20-plus years. The purpose of this study was to develop protocols for rearing D. antillarum within a novel 1800-L recirculating aquaculture system capable of scaled production. Five separate experiments investigated larval development in response to diet quantity, diet composition, and initial stocking density within 40-L replicate culture tanks. The initial experiment was used to develop a microalgae reference diet consisting of Tisochrysis lutea and Chaetoceros sp. and revealed similar growth and survival between high quantity (40.0 × 103 cells mL−1) and low quantity (10.0 × 103 cells mL−1) treatments at 21 days post-fertilization (DPF). Experiments 2–4 examined diet quality by comparing carbon-equivalent microalgae compositions. Mixed diets containing Rhodomonas lens outperformed the reference diet in multiple experiments and a tripartite diet containing all three species resulted in significantly higher survival at 42 DPF. The highest growth overall occurred from a monoalgal R. lens diet, which indicated that this species is critically important. Further observations of density-dependent growth dynamics revealed that initial stocking densities > 1 larvae mL−1 significantly reduced growth over 28 DPF. Data generated were used to establish fundamental larviculture protocols that have since led to the production of over 1000 juveniles.