Search

Marine mammals can play important ecological roles in aquatic ecosystems, and their presence can be key to community structure and function. Consequently, marine mammals are often considered indicators of ecosystem health and flagship species. Yet, historical population declines caused by exploitation, and additional current threats, such as climate change, fisheries bycatch, pollution and maritime development, continue to impact many marine mammal species, and at least 25% are classified as threatened (Critically Endangered, Endangered or Vulnerable) on the IUCN Red List. Conversely, some species have experienced population increases/recoveries in recent decades, reflecting management interventions, and are heralded as conservation successes. To continue these successes and reverse the downward trajectories of at-risk species, it is necessary to evaluate the threats faced by marine mammals and the conservation mechanisms available to address them. Additionally, there is a need to identify evidence-based priorities of both research and conservation needs across a range of settings and taxa. To that effect we: (1) outline the key threats to marine mammals and their impacts, identify the associated knowledge gaps and recommend actions needed; (2) discuss the merits and downfalls of established and emerging conservation mechanisms; (3) outline the application of research and monitoring techniques; and (4) highlight particular taxa/populations that are in urgent need of focus.

To achieve sustainable shark fisheries, it is key to understand not only the biological drivers and environmental consequences of overfishing, but also the social and economic drivers of fisher behavior. The extinction risk of sharks is highest in coastal tropical waters, where small-scale fisheries are most prevalent. Small-scale fisheries provide a critical source of economic and nutritional security to coastal communities, and these fishers are among the most vulnerable social and economic groups. We used Kenya's and Zanzibar's small-scale shark fisheries, which are illustrative of the many data-poor, small-scale shark fisheries worldwide, as case studies to explore the relationship between extinction risk and the economic and nutritional value of sharks. To achieve this, we combined existing data on shark landings, extinction risk, and nutritional value with sales data at 16 key landing sites and information from interviews with 476 fishers. Shark fisheries were an important source of economic and nutritional security, valued at >US$4 million annually and providing enough nutrition for tens of thousands of people. Economically and nutritionally, catches were dominated by threatened species (72.7% and 64.6-89.7%, respectively). The most economically valuable species were large and slow to reproduce (e.g. mobulid rays, wedgefish, and bull, silky, and mako sharks) and therefore more likely to be threatened with extinction. Given the financial incentive and intensive fishing pressure, small-scale fisheries are undoubtedly major contributors to the decline of threatened coastal shark species. In the absence of effective fisheries management and enforcement, we argue that within small-scale fisheries the conditions exist for an economically incentivized feedback loop in which vulnerable fishers are driven to persistently overfish vulnerable and declining shark species. To protect these species from extinction, this feedback loop must be broken., (© 2024 The Authors. Conservation Biology published by Wiley Periodicals LLC on behalf of Society for Conservation Biology.)

Taxonomic data are a scientific common. Unlike nomenclature, which has strong governance institutions, there are currently no generally accepted governance institutions for the compilation of taxonomic data into an accepted global list. This gap results in challenges for conservation, ecological research, policymaking, international trade, and other areas of scientific and societal importance. Consensus on a global list and its management requires effective governance and standards, including agreed mechanisms for choosing among competing taxonomies and partial lists. However, governance frameworks are currently lacking, and a call for governance in 2017 generated critical responses. Any governance system to which compliance is voluntary requires a high level of legitimacy and credibility among those by and for whom it is created. Legitimacy and credibility, in turn, require adequate and credible consultation. Here, we report on the results of a global survey of taxonomists, scientists from other disciplines, and users of taxonomy designed to assess views and test ideas for a new system of taxonomic list governance. We found a surprisingly high degree of agreement on the need for a global list of accepted species and their names, and consistent views on what such a list should provide to users and how it should be governed. The survey suggests that consensus on a mechanism to create, manage, and govern a single widely accepted list of all the world's species is achievable. This finding was unexpected given past controversies about the merits of list governance.

Billfish species (families Istiophoridae and Xiphiidae) are caught in artisanal, recreational, and commercial fisheries throughout the Western Indian Ocean region. However, data and information on the interactions among these fisheries and the ecology of billfish in the WIO are not well understood. Using an in-depth analysis of peer-reviewed articles, grey literature, observation studies, and authors' insider knowledge, we summarize the current state of knowledge on billfish fisheries in 10 countries. To describe historical and current trends, we examined fisheries statistics from governmental and non-governmental agencies, sportfishing clubs' reports, diaries of sportfishing captains, and the catch and effort databases of the Indian Ocean Tuna Commission. We highlight two key points. First, billfish fisheries in the Western Indian Ocean are highly diverse, comprising two distinct segments-coastal and oceanic. However, data are poor for most countries with significant gaps in information especially for sport and artisanal fisheries. Second, the evidence assembled showed that billfish species have immense social, cultural, and economic value. Swordfish are targeted by both large-scale and semi-industrial fisheries, while other billfish species, particularly marlin, are highly sought after by sport fisheries in most countries. Our paper provides a comprehensive review of billfish fisheries and available information in the context of the WIO underscoring the need to strengthen data collection and reporting, citizen science, and collaborative sustainable development and management of billfish., Supplementary Information: The online version contains supplementary material available at 10.1007/s11160-022-09725-8., Competing Interests: Conflict of interestThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2022, Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Coral reefs face an increased number of environmental threats from anthropomorphic climate change and pollution from agriculture, industries and sewage. Because environmental changes lead to their compositional and functional shifts, coral reef microbial communities can serve as indicators of ecosystem impacts through development of rapid and inexpensive molecular monitoring tools. Little is known about coral reef microbial communities of the Western Indian Ocean (WIO). We compared taxonomic and functional diversity of microbial communities inhabiting near-coral seawater and sediments from Kenyan reefs exposed to varying impacts of human activities. Over 19,000 species (bacterial, viral and archaeal combined) and 4,500 clusters of orthologous groups of proteins (COGs) were annotated. The coral reefs showed variations in the relative abundances of ecologically significant taxa, especially copiotrophic bacteria and coliphages, corresponding to the magnitude of the neighboring human impacts in the respective sites. Furthermore, the near-coral seawater and sediment metagenomes had an overrepresentation of COGs for functions related to adaptation to diverse environments. Malindi and Mombasa marine parks, the coral reef sites closest to densely populated settlements were significantly enriched with genes for functions suggestive of mitigation of environment perturbations including the capacity to reduce intracellular levels of environmental contaminants and repair of DNA damage. Our study is the first metagenomic assessment of WIO coral reef microbial diversity which provides a much-needed baseline for the region, and points to a potential area for future research toward establishing indicators of environmental perturbations., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Wambua, Gourlé, de Villiers, Karlsson-Lindsjö, Wambiji, Macdonald, Bongcam-Rudloff and de Villiers.)

The Baraka's whipray (Maculabatis ambigua) is a major constituent of small-scale fisheries catch in the south-western Indian Ocean. Despite this, little is known of its life-history or exploitation status. We provide the first estimates of crucial life-history parameters and the maximum intrinsic population growth rate r max , using specimens collected from small-scale fisheries landings in Kenya, Zanzibar and Madagascar (with northern Madagascar representing a range extension for this species). We assess the relative risk of overexploitation by combining r max with estimates of total Z, fishing F, and natural M mortality, and an estimate of the exploitation ratio E. The data indicate that Baraka's whipray is a medium-sized, fast-growing, early maturing species, with a relatively long lifespan. This results in a high r max relative to many other elasmobranchs, which when combined with estimates of F suggests that the species is not at imminent risk of extinction. Yet, estimates of exploitation ratio E indicate likely overfishing for the species, with full recruitment to the fishery being post-maturation and exploitation occurring across a broad range of age and size classes. Thus, Baraka's whipray is unlikely to be biologically sustainable in the face of current fisheries pressures. This paper makes an important contribution to filling the gap in available data and is a step towards developing evidence-based fisheries management for this species. Further, it demonstrates a simple and widely applicable framework for assessment of data-poor elasmobranch exploitation status and extinction risk., (© 2020 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.)

Thyroid hormone (TH) is involved in regulating the reproduction of vertebrates. Its physiological action in the target tissues is due to the conversion of TH by iodothyronine deiodinases. In this study, we aimed to clone and characterize type 2 (sdDio2) and type 3 (sdDio3) of the sapphire devil Chrysiptera cyanea, a tropical damselfish that undergoes active reproduction under long-day conditions, and to study the involvement of THs in the ovarian development of this species. When the cDNAs of sdDio2 and sdDio3 were partially cloned, they had deduced amino acid sequences of lengths 271 and 267, respectively, both of which were characterized by one selenocysteine residue. Real-time quantitative PCR (qPCR) revealed that both genes are highly expressed in the whole brain, and sdDio2 and sdDio3 are highly transcribed in the liver and ovary, respectively. In situ hybridization analyses showed positive signals of sdDio2 and sdDio3 transcripts in the hypothalamic area of the brain. Little change in mRNA abundance of sdDio2 and sdDio3 in the brain was observed during the vitellogenic phases. It is assumed that simultaneous activation and inactivation of THs occur in this area because oral administration of triiodothyronine (T3), but not of thyroxine (T4), upregulated mRNA abundance of both genes in the brain. The transcript levels of sdDio2 in the liver and sdDio3 in the ovary increased as vitellogenesis progressed, suggesting that, through the metabolism of THs, sdDio2 and sdDio3 play a role in vitellogenin synthesis in the liver and yolk accumulation/E2 synthesis in the ovary. Taken together, these results suggest that iodothyronine deiodinases act as a driver for vitellogenesis in tropical damselfish by conversion of THs in certain peripheral tissues., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Type II iodothyronine deiodinase (D2) converts 3,5,3',5'-tetraiodothyronine to 3,5,3'-triiodothyronine and is involved in regulating thyroid hormone-dependent processes in various tissues. D2 mRNA expression in the mediobasal hypothalamus is affected by photoperiod, which influences reproductive processes in temperate birds and mammals. We examined whether D2 mRNA is expressed in the hypothalamus (located in the forebrain within the diencephalon area) and whether its abundance is affected by day length, temperature, or food availability in the tropical spinefoot, Siganus guttatus, which is endemic to tropical monsoon areas. The reverse transcription-polymerase chain reaction (RT-PCR) revealed that D2 mRNA is expressed in various brain regions. The abundance of hypothalamic D2 mRNA was higher at 12.00h than at 06.00h or 24.00h. Rearing fish under constant dark conditions resulted in a decrease in D2 mRNA abundance during the subjective night. A single injection of melatonin lowered D2 mRNA abundance within 3h. Collectively, it appears that hypothalamic D2 mRNA abundance is regulated by the circadian system and/or melatonin. No differences in D2 mRNA abundance were observed, when fish were reared at 20, 25, and 30°C. However, food deprivation stimulated D2 mRNA expression during the daytime. These results suggest that photoperiodic and nutritive conditions affect hypothalamic D2 mRNA expression in S. guttatus., (Copyright © 2011 Elsevier Inc. All rights reserved.)