Sperm whales, the largest of the toothed whales and among the deepest-diving mammals on Earth, present a formidable challenge for conservation planners. They travel enormous distances across national jurisdictions and the open ocean, moving between feeding grounds, breeding areas and migration corridors that can span thousands of kilometres. Alexander Lomas, from the University of Exeter and lead author of the study, emphasized that this mobility is precisely why protection must cover extensive areas. By identifying core habitats, the study provides a baseline from which such protection can begin to be built, but the researchers also found a shifting patchwork of suitable areas as the climate changes, which they say highlights the need for dynamic protection rather than static, fixed boundaries.

To understand where sperm whales live today and where they are likely to live in the future, the team employed ensemble ecological niche models, a technique that combines multiple statistical modelling approaches to predict species distributions. These models were trained on whale survey data gathered by nine research groups working across the western Indian Ocean, including the Marine Megafauna Conservation Organisation, GLOBICE, the African Aquatic Conservation Fund and the IndoCet Consortium, alongside work by governments and non-governmental organisations from countries around the region. Ensemble approaches are considered more robust than single models because they average out the biases and uncertainties of individual methods, producing more reliable predictions of where environmental conditions are suitable for a species.

The study’s projections of future habitat loss are striking, and they vary considerably depending on which greenhouse gas emissions pathway humanity follows. Under the so-called optimistic scenario, known as SSP1-2.6, in which global emissions decline rapidly, 40 percent of suitable sperm whale habitat in the south-west Indian Ocean is projected to be lost by the year 2100. Under the intermediate scenario, SSP2-4.5, the projected loss is 37 percent. Perhaps counterintuitively, the pessimistic scenario, SSP5-8.5, projects a smaller direct habitat loss of 20 percent, but the researchers caution that this figure comes with a major caveat: in that scenario, stronger ocean currents predicted under extreme warming appear to offset some of the damage caused by rising temperatures, although the team did not assess the wider ecosystem impacts of such extreme climate change, which could prove harmful to the whales.

The physical structure of the seafloor emerged as a critical determinant of sperm whale presence. The findings suggest that underwater topography, particularly steep slopes, is key for the species, because these slopes promote the upwelling of nutrient-rich waters from the depths into sunlit layers where the whales’ prey can thrive. Sperm whales feed almost exclusively on deep-sea squid, hunting them in the darkness hundreds or even thousands of metres below the surface using powerful echolocation clicks. Where nutrient delivery sustains productive waters, squid populations flourish, and the whales follow. The study identified long-term core habitat, places that remain key for the whales despite warming, particularly off the Seychelles and Mauritius and along the steeply shelving ridges that lie between them, including areas around the vast Saya de Malha bank.

Dr Jeremy Kiszka, a Professor at Florida International University in Miami who was involved in the study, noted that climate change is predicted to substantially reduce suitable habitat for sperm whales in the south-west Indian Ocean, but that the team also identified places that could remain important refuges for these animals through the end of the century. These refugia, where suitable conditions are projected to persist even as the surrounding ocean changes, represent natural anchors for conservation planning. Protecting such areas could safeguard breeding females and their calves, which tend to occupy predictable ranges, while ensuring that the wider network of habitats the whales depend upon remains connected across the region.

The historical context of the region adds urgency to the findings. Sperm whales in the south-west Indian Ocean were targeted by the whaling industry in the past, and evidence on their numbers and movements has been limited since then. The new study draws on data from a series of research expeditions carried out over the last two decades, representing some of the first systematic scientific attention these populations have received since the whaling era. Dr Kirsten Young, who leads the Exeter Cetacean Research Group, described the experience of encountering the whales hundreds of kilometres from land around Saya de Malha bank as incredible, noting that the team is among the first to study these animals since the days of whaling. She added that the threats they face are a reminder of how far human influence reaches into the natural world, and of the urgent need to reduce human impact.

The implications extend well beyond a single charismatic species. Dr Young argued that extensive, dynamic protection will not only benefit iconic species like sperm whales, but that protecting large, interconnected swathes of the ocean would allow the wider ecosystem, and the multitude of species within it, to recover and thrive. Large marine protected areas that encompass the full range of a wide-ranging predator inevitably capture the habitats of countless other organisms, from the deep-sea squid at the base of the whales’ diet to the tuna, seabirds and sharks that share the same productive waters. In this sense, sperm whales can function as an umbrella species, with conservation measures designed around their needs delivering benefits that cascade through entire food webs.

The international collaboration underpinning the study offers a model for future ocean science. Lomas stressed that the paper highlights the benefits of international scientific collaboration, noting that it depended on data from nine research groups and on work by governments and non-governmental organisations from different countries around the Indian Ocean. Violaine Dulau, chair of IndoCet, the Indian Ocean network for cetacean research, said that by bringing together data and expertise from across the western Indian Ocean, researchers can finally see the bigger picture, and that thinking at the scale of the ocean is essential to understanding the habitats sperm whales depend on and what their future may look like. This pooling of survey effort across national boundaries mirrors the scale of the animals themselves and the scale of the threats they face.

As the ocean continues to warm, the study’s central message is that conservation planning must anticipate the future rather than merely record the present. Dr Young concluded that in a rapidly changing ocean, scientists need to know not only where animals are today, but where suitable habitat is most likely to persist in the future. Static protected areas drawn around current whale distributions could inadvertently protect waters that become unsuitable within decades, while missing the refugia that will matter most by 2100. The combination of long-term core habitat identification and climate-informed projections offers policymakers a template for adaptive management, one in which protection networks can expand, contract and shift in step with the moving mosaic of suitable conditions. For a species that survived industrial whaling but now confronts a warming ocean, the difference between static and dynamic conservation may determine whether the south-west Indian Ocean’s sperm whales endure through the century ahead.

Subject of Research: Climate-driven shifts in sperm whale habitat and conservation planning in the south-west Indian Ocean

Article Title: Sperm whale study highlights need for ‘extensive & dynamic’ conservation

Article References: Sperm whale study highlights need for ‘extensive & dynamic’ conservation. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: sperm whales, climate change, marine conservation, south-west Indian Ocean, habitat modelling, High Seas Treaty, Endangered Species Research, ecological niche models, Seychelles, Mauritius, deep-sea squid, ocean warming

The study, led by Dishti Dabeedass of the University of Mauritius together with colleagues at Hokkaido University in Japan and Jeju National University in the Republic of Korea, focused on the floating-cage facility at Pointe-aux-Feuilles, operational since 2002 and producing roughly 3,000 tons of fish annually. Fish farming releases feed residues and metabolic waste into the surrounding water, creating a nutrient-enriched micro-ecosystem in the lagoon. These conditions frequently trigger substantial proliferation of opportunistic macroalgae that cling naturally to aquaculture cages, ropes and nets. Rather than treating this growth as a nuisance, the research team asked a different question: what are these seaweeds made of, and could they be worth something?

To find out, the divers hand-collected approximately one kilogram of fresh biomass from each of seven seaweed taxa at depths of no more than two metres, carefully picking from multiple individuals to ensure representative sampling while minimising environmental disturbance. The samples, spanning green, brown and red macroalgal functional groups, were sealed in sterile bags, transported on ice and stored at minus 80 degrees Celsius to preserve their biochemical integrity. Because many tropical macroalgal genera are notoriously plastic in form and include cryptic species that defy visual identification, the team went beyond morphology, extracting genomic DNA and sequencing chloroplast and mitochondrial marker genes, including tufA, psbA, cox3 and rbcL, confirming species identities through nucleotide BLAST searches and depositing the sequences in GenBank.

The molecular work resolved the seven colonisers into a taxonomically diverse line-up: the green seaweeds Ulva torta in its tubular form, Ulva lactuca in its blade form and Caulerpa racemosa; the brown alga Padina sanctae-crucis lineage number two; and the red seaweeds Dasya corymbifera, Hypnea cornuta lineage number three and Gracilaria rangiferina. Each pooled sample was then subjected to a battery of validated Association of Official Analytical Chemists protocols and spectrophotometric assays, quantifying ascorbic acid, total phenolics, total flavonoids, beta-carotene, chlorophyll a and monomeric anthocyanins, with every measurement performed in triplicate.

The headline result came from the green seaweeds. Ulva torta exhibited the highest ascorbic acid concentration at 640 plus or minus 25.6 milligrams per kilogram of fresh weight, with Ulva lactuca and Hypnea cornuta close behind. Green macroalgae, with their chlorophyll-dominated photosynthetic machinery and rapid growth dynamics, are physiologically primed for ascorbate biosynthesis, which serves photoprotection and redox regulation. The authors note that these vitamin C levels are nutritionally significant and comparable to values reported in selected terrestrial plant sources, although direct comparisons warrant caution because of methodological differences. What makes the finding striking is that the biomass was growing passively within a fish farm, without targeted fertilisation or controlled cultivation, demonstrating that nutritionally valuable seaweed can occur naturally within lagoonal environments suited to Integrated Multi-Trophic Aquaculture, or IMTA.

The brown and red algae told a different chemical story. Padina sanctae-crucis dominated the secondary-metabolite league tables, posting the highest total phenolic content at 22.25 plus or minus 5.74 milligrams per kilogram fresh weight and the highest flavonoid content at 398.8 plus or minus 14.6 milligrams per kilogram. Brown algae synthesise phlorotannins, a unique class of polyphenols produced via the acetate-malonate pathway and absent from other algal lineages, compounds that serve antioxidant defence, ultraviolet screening and anti-herbivore protection in shallow, high-irradiance lagoons. The red seaweeds, meanwhile, excelled at carotenoid and pigment chemistry: Dasya corymbifera recorded the highest beta-carotene concentration at 28.18 plus or minus 2.22 milligrams per kilogram fresh weight and the highest chlorophyll a content at 24.00 plus or minus 0.05 milligrams per kilogram, while Dasya corymbifera and Gracilaria rangiferina were the only species with detectable monomeric anthocyanins, at 0.301 and 0.167 milligrams per kilogram respectively.

Statistical analysis confirmed that these differences were far from random. Analysis of variance revealed highly significant species effects across every antioxidant and pigment parameter measured, with effect sizes approaching the theoretical maximum; for chlorophyll a and anthocyanins, species identity explained essentially all of the observed variation. The authors stress an important interpretive caveat, however. Each species was represented by a single composite sample pooled from multiple individuals, so the triplicate assays reflect analytical precision rather than natural within-species variability, and the statistical comparisons describe differences among composite samples rather than estimates of biological variation across populations.

The team is equally candid about the environmental dimension of the work. Although fish farms are commonly associated with localised nutrient enrichment, dissolved nutrient concentrations were not measured during sampling, and no reference populations from non-aquaculture sites were included. The study therefore cannot establish a direct causal link between aquaculture-derived nutrients and the observed antioxidant profiles. Seaweed biochemistry is known to be strongly governed by nutrient availability: under nutrient-replete conditions, macroalgae tend to prioritise growth and accumulate proteins, chlorophylls and water-soluble vitamins such as ascorbic acid, whereas nutrient limitation shifts metabolism toward carbon-rich secondary metabolites like phenolics and flavonoids. Disentangling these nutrient-driven responses will require seasonal sampling, water-quality monitoring and comparative studies across aquaculture and non-aquaculture habitats, priorities the authors lay out for future research.

Even with those caveats, the implications for Mauritius and similar small island developing states are considerable. The global seaweed sector is worth more than eight billion US dollars annually, dominated by Asian producers, yet Mauritius, despite documenting 435 seaweed species and commanding sovereign rights over an Exclusive Economic Zone of nearly 1.9 million square kilometres, harvests seaweed only at limited artisanal scale. In an IMTA framework, seaweeds act as extractive organisms that assimilate dissolved nutrients and improve water quality while generating marketable biomass, and the new biochemical profiles provide a baseline for choosing which species to pair with finfish. Fast-growing green species such as Ulva could supply vitamin C-rich functional food ingredients, brown species like Padina could feed nutraceutical and cosmeceutical pipelines with phlorotannin-rich extracts, and red species such as Dasya corymbifera could serve as marine sources of carotenoids prized for their stability and bioactivity. The research aligns with Sustainable Development Goals 12 and 14 on responsible consumption and marine stewardship, and the authors argue that further work on seasonal variability, nutrient flux dynamics and bioavailability will be needed to translate baseline chemistry into commercial opportunity. For now, the message from the Mauritian lagoon is clear: the structures built to farm fish are also quietly growing some of the ocean’s most biochemically interesting food, and nobody is harvesting it.

Subject of Research: Antioxidant profiles of edible seaweeds colonising lagoonal aquaculture structures in Mauritius

Article Title: Lagoonal aquaculture structures support antioxidant rich edible seaweeds with potential for integrated multitrophic aquaculture in Mauritius

Article References: Dabeedass, D., Akita, S., Vieira, C., Tojo, N., Yao, F., & Nazurally, N. (2026). Lagoonal aquaculture structures support antioxidant rich edible seaweeds with potential for integrated multitrophic aquaculture in Mauritius. Discover Oceans, 3(1), Article 45. https://doi.org/10.1007/s44289-026-00157-x

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00157-x

Keywords: seaweed, aquaculture, Mauritius, antioxidants, vitamin C, IMTA, phlorotannins, beta-carotene, Ulva, blue economy, lagoon, nutraceuticals

The headline finding is a stark contrast between scale and knowledge. Mauritius commands an Exclusive Economic Zone of roughly 2.3 million square kilometers and depends heavily on marine resources for food security and economic development. Yet while the island’s corals, fishes, and seagrasses have received sustained research attention, its crustaceans have not. No recent comprehensive inventory or checklist exists. The most detailed records date back to the nineteenth and early twentieth centuries, when naturalists such as H. Milne-Edwards and E. J. Miers described species from what was then known as L’Île de France. Paul Carié’s early twentieth-century work documented 147 decapod species across stomatopods, anomurans, macrurans, and brachyurans, laying a foundation that subsequent researchers have struggled to update.

The review compiles records from 61 crustacean families in Mauritius, with the crab families Xanthidae and Portunidae, the spider crabs of Epialtidae, and the hermit crabs of Diogenidae among the most frequently reported. But the authors caution that this apparent diversity should be interpreted carefully. Many records come from historical surveys whose species names and classifications may no longer align with modern taxonomy, and older literature remains incompletely digitized. Research effort has also been heavily skewed: from the late twentieth century onward, work focused largely on peracarid crustaceans, particularly amphipods and isopods. Christine Appadoo and Derek Steele’s 1998 study recorded 69 gammaridean amphipod species, including numerous new records and undescribed taxa, and later work by Guerra-García on caprellids and by other teams on isopods and hermit crabs added new species and Western Indian Ocean records.

Recent decades have seen only sporadic contributions, such as investigations of sponge-associated crustaceans, the rediscovery of the sponge crab Cryptodromia fallax, and the description of the lobster Enoplometopus holthuisi. The authors argue that the existing literature is better viewed as a historical baseline than a faithful snapshot of current diversity. They call for an updated checklist incorporating verified taxonomy, recent field surveys, molecular identification, and detailed distributional data, along with a reference library of DNA barcodes deposited in public databases such as NCBI and BOLD to support future biodiversity studies and detect whether historically reported species still persist.

Why does this gap matter so much? Globally, crustaceans are among the most functionally important animals in the ocean. They occupy nearly every trophic position, serving as primary consumers, detritivores, predators, and prey. Krill dominate the diets of mobulid rays, calanoid copepods sustain certain jellyfish, and the swimming crab Charybdis smithii feeds yellowfin tuna and pygmy sperm whales. In Mauritius, crustaceans have been reported as the dominant prey of albacore tuna, which uses Mauritian waters as a spawning ground, and decapods have turned up in the stomachs of apex predators from Mauritian and Réunion waters. Predators as large as gray whales track the abundance of benthic crustacean prey, meaning that shifts in crustacean populations can ripple through entire food webs and reshape the distribution of commercially vital fish stocks.

Crustaceans are also the ocean’s cleanup crew and its engineers. As scavengers, they process dead organic matter and can, in some ecosystems, break down up to 75 percent of available plant-derived organic material, with amphipods proving especially dominant from coastal shallows to hydrothermal vents. Burrowing thalassinidean crustaceans are considered among the most effective marine bioengineers: their bioturbation redistributes sediments and nutrients, enhances oxygenation, and stimulates microbial activity and nitrogen cycling. Evidence of these functions in Mauritius is thin but suggestive—crab burrow abundance has been used as an indicator of ecosystem recovery in the island’s mangrove forests—but the broader role of crustaceans in Mauritian nutrient cycling and sediment dynamics remains essentially unstudied.

The review also highlights the striking symbiotic lives of crustaceans, from obligate coral-dwelling trapeziid crabs that defend their pocilloporid hosts against corallivores, to coral gall crabs, to elaborate triple symbioses in which a goby, a pistol shrimp, and a porcellanid crab share a single burrow to mutual benefit. In Mauritius, however, documented symbioses are limited to scattered observations such as crabs inhabiting sponges and barnacle associations, leaving a rich field of research essentially untouched. Economically, the picture is equally lopsided. Fisheries and aquaculture contribute roughly 10.3 percent of Mauritius’s GDP excluding tourism and employ up to 10,000 people, yet in 2023 the country exported only about USD 187,000 worth of crustaceans while importing USD 16.2 million, mainly from India, Madagascar, and Vietnam—a trade imbalance that exposes the island to global price shocks and signals untapped potential for local production, aquaculture, and blue-economy growth.

Then there is chitin. Extracted from crustacean shells and processing waste, chitin and its derivative chitosan are finding applications across medicine, agriculture, and environmental technology: wound dressings and tissue-engineering scaffolds, antimicrobial and anticancer materials, plant-defense biostimulants and biopesticides, and adsorbents that strip heavy metals and arsenic from water. Crustaceans themselves serve as bioindicators, accumulating heavy metals, microplastics, and nanoplastics in ways that reveal ecosystem contamination. A systematic review has even identified Mauritius among the African countries with the highest reported use of marine animals, including crustaceans, in traditional medicine. Yet the biotechnological and pharmaceutical potential of Mauritian crustaceans remains almost entirely unexplored.

Climate change looms over all of it. Atmospheric carbon dioxide has climbed from about 278 ppm pre-industrially to over 421 ppm by 2023, driving ocean acidification projected to lower global pH by roughly 0.4 units by 2100. The Indian Ocean warmed by approximately 0.7 degrees Celsius between 1982 and 2021, faster than other basins. These stressors act on crustaceans at every level, from DNA repair and protein synthesis to haemolymph chemistry, immune function, molting, calcification, reproduction, and behavior. Flic en Flac lagoon offers site-specific warning signs: maximum sea surface temperatures rose from 29 degrees Celsius in 2000–2001 to 31 degrees by 2017–2019, while pH has become increasingly variable. Meanwhile, hard and soft coral cover in parts of Mauritius declined by roughly 40 and 83 percent respectively between 2004 and 2019, and lagoon sponges declined by up to 40.2 percent—collapses that threaten the habitat-dependent and symbiotic crustaceans relying on these structures.

Responses to acidification vary widely among species and over time. Crustaceans may tolerate acidification better than some calcifiers because their exoskeletons are largely calcite-based and rely on bicarbonate, but chronic exposure has been linked to reduced claw hardness, exoskeletal thinning in king crabs, altered mineral composition in shrimps, and delayed post-moult hardening. Behavioral changes add another layer of vulnerability: warming can push shrimps to forage recklessly in the presence of predators, acidification impairs mud crab foraging, and combined stressors disrupt the acoustic signaling of snapping shrimps. Warming and hypoxia also reshape disease dynamics, potentially raising infection risks in both wild populations and future aquaculture operations. The review’s authors are explicit about what comes next: Mauritius needs updated biodiversity inventories, integrative taxonomic and molecular research, long-term monitoring across coral reefs, seagrass meadows, and mangroves, and targeted multi-stressor studies of climate impacts. Without that effort, declines among poorly known, endemic, or economically important crustaceans could unfold silently, invisible beneath waters the nation depends upon.

Subject of Research: Marine crustacean biodiversity and climate-change vulnerability in Mauritius

Article Title: Current knowledge of marine crustaceans in Mauritius and their global importance in a changing climate

Article References: Bhuvaneshwaree, S., Nadeem, N., Sunita, F., & Mandić, J. (2026). Current knowledge of marine crustaceans in Mauritius and their global importance in a changing climate. Discover Oceans, 3(1), Article 61. https://doi.org/10.1007/s44289-026-00171-z

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00171-z

Keywords: marine crustaceans, Mauritius, biodiversity, climate change, ocean acidification, ocean warming, Malacostraca, Decapoda, chitin, fisheries, ecosystem engineers, Indian Ocean