Manta and devil rays are filter-feeding elasmobranchs that are found circumglobally in tropical and subtropical waters. Although relatively understudied for most of the Twentieth century, public awareness and scientific research on these species has increased dramatically in recent years. Much of this attention has been in response to targeted fisheries, international trade in mobulid products, and a growing concern over the fate of exploited populations. Despite progress in mobulid research, major knowledge gaps still exist, hindering the development of effective management and conservation strategies. We assembled 30 leaders and emerging experts in the fields of mobulid biology, ecology, and conservation to identify pressing knowledge gaps that must be filled to facilitate improved science-based management of these vulnerable species. We highlight focal research topics in the subject areas of taxonomy and diversity, life history, reproduction and nursery areas, population trends, bycatch and fisheries, spatial dynamics and movements, foraging and diving, pollution and contaminants, and sub-lethal impacts. Mobulid rays remain a poorly studied group, and therefore our list of important knowledge gaps is extensive. However, we hope that this identification of high priority knowledge gaps will stimulate and focus future mobulid research.
Conservation Targets & Planning
Oceanographers have an increasing responsibility to ensure that the outcomes of scientific research are conveyed to the policy-making sphere to achieve conservation and sustainable use of marine biodiversity. Zooplankton monitoring projects have helped to increase our understanding of the processes by which marine ecosystems respond to climate change and other environmental variations, ranging from regional to global scales, and its scientific value is recognized in the contexts of fisheries, biodiversity and global change studies. Nevertheless, zooplankton data have rarely been used at policy level for conservation and management of marine ecosystems services. One way that this can be pragmatically and effectively achieved is via the development of zooplankton indicators, which could for instance contribute to filling in gaps in the suite of global indicators to track progress against the Aichi Biodiversity Targets of the United Nations Strategic Plan for Biodiversity 2010–2020. This article begins by highlighting how under-represented the marine realm is within the current suite of global Aichi Target indicators. We then examine the potential to develop global indicators for relevant Aichi Targets, using existing zooplankton monitoring data, to address global biodiversity conservation challenges.
Increased coastal development and rising sea levels as a result of continuing climate-change put coastal regions at risk from flooding and inundation. A common mitigation response is the construction and upgrade of hard coastal protection structures, such as breakwaters, seawalls, and groynes. The alteration of the coast, together with the introduction of novel materials into coastal waters can negatively impact adjacent habitats and associated organisms. The implementation of management plans that involve scientists, as well as a variety of other stakeholders offer an opportunity to minimise adverse effects to biodiversity or even enhance it, while still protecting infrastructure and people. This study examines the management of an Australian breakwater upgrade and the progressive design finding process, including stakeholder engagement, determination of assessment criteria, and environmental impact assessment. In the course of the latter, scientific research led to the rediscovery of a presumed extinct algal species, Nereia lophocladia, which created an additional challenge and temporarily halted the upgrade. To accommodate this, the breakwater design solution was modified to avoid any impacts on the algal population and, in order to maximise the species' survival, novel ecological engineering approaches were proposed as mitigation strategies. Our case study underpins the value of evidence-based conservation and cooperation among stakeholders as important tools for minimising ecological impacts from coastal infrastructure upgrades.
We developed a rockfish habitat model to evaluate a network of Rockfish Conservation Areas (RCAs) implemented by Fisheries and Oceans Canada to reverse population declines of inshore Pacific rockfishes (Sebastes spp.). We modeled rocky reef habitat in all nearshore waters of southern British Columbia (BC) using a supervised classification of variables derived from a bathymetry model with 20 m2 resolution. We compared the results from models at intermediate (20 m2) and fine (5 m2) resolutions in five test areas where acoustic multibeam echosounder and backscatter data were available. The inclusion of backscatter variables did not substantially improve model accuracy. The intermediate-resolution model performed well with an accuracy of 75%, except in very steep habitats such as coastal inlets; it was used to estimate the total habitat area and the percent of rocky habitat in 144 RCAs in southern BC. We also compared the amount of habitat estimated by our 20 m2 model to the 100 m2 management model used to designate the RCAs and found that a slightly lower proportion of habitat (18% vs 20%) but a considerably smaller area (400 km2 vs 1370 km2) is protected in the RCAs, likely as a result of the poor resolution of the original model. Empirically derived maps of important habitats, such as rocky reefs, are necessary to support effective marine spatial planning and to design and evaluate the efficacy of management and conservation actions.
Wildlife-focused tourism is often considered as having the potential to play an integral part of threatened species conservation efforts, particularly through financial support. We focused on the direct financing of conservation by investigating tourists’ willingness to pay to snorkel with reef manta rays (Mobula alfredi) at Barefoot Manta, an ecotourism resort in the Yasawa group of islands in Fiji. Our results indicate that 82.4% of people surveyed would be willing to pay a mean value of ~ USD $9.2 (SE 0.9) more than the current cost, a 28% increase. Also, 89% of people surveyed would be willing to pay a mean value of ~ USD $10.2 (SE 0.9) more for a hypothetical scenario where they would snorkel with 50% fewer people, a 31% increase. We also investigated tourists’ willingness to make voluntary donations to the local community above an existing payment of ~ USD $10 that is built into the current snorkel payment of ~ USD $32.5. On average, 91.3% of the tourists interviewed were willing to donate additional funds with an average additional donation of ~ USD $8.6 (SE 0.5) to the community to pay for educational and environmental support, an 86% increase. There were few significant relationships between willingness to pay and demographic factors (including age, income, nationality, education, and others), suggesting that willingness to pay was widely held by the tourist population staying at Barefoot Manta Resort. Together, these results indicate that wildlife-based nature tourism could represent a potential, but not unlimited, income source to fund conservation in the Yasawa group, Fiji islands, and that conservation can arise from partnerships between local communities and the tourism sector
Many broadly distributed migratory species exhibit fidelity to fine-scale areas that support vital life history requirements (e.g., resource acquisition, reproduction). Thus, such areas are critical for population dynamics and are of high conservation priority. Leatherback sea turtles are among the world’s most widely distributed species, and their breeding and feeding areas are typically separated by thousands of kilometres. In this study, we analysed turtle-borne video data on daytime feeding rates and energy acquisition in Nova Scotia, Canada, to quantify the importance of this discrete, seasonal foraging area for leatherback energy requirements. Based on daytime foraging only, we estimate that a single foraging season in Nova Scotia could support 59% of a non-breeding leatherback’s annual energy budget, and 29% of energetic requirements for a female on a typical 2-year reproductive cycle. However, maximum energy intake rates for leatherbacks are nearly four times lower than those of mammals and birds due the low energy content of leatherbacks’ gelatinous zooplankton prey. These results illustrate that high quality, local-scale foraging areas such as Nova Scotia are critically important to the stability and future growth of the leatherback population in the Northwest Atlantic Ocean. Thus, as with other migratory species, efforts to reduce threats and maintain habitat quality in such areas should be high conservation priorities.
Mineral exploitation has spread from land to shallow coastal waters and is now planned for the offshore, deep seabed. Large seafloor areas are being approved for exploration for seafloor mineral deposits, creating an urgent need for regional environmental management plans. Networks of areas where mining and mining impacts are prohibited are key elements of these plans. We adapt marine reserve design principles to the distinctive biophysical environment of mid-ocean ridges, offer a framework for design and evaluation of these networks to support conservation of benthic ecosystems on mid-ocean ridges, and introduce projected climate-induced changes in the deep sea to the evaluation of reserve design. We enumerate a suite of metrics to measure network performance against conservation targets and network design criteria promulgated by the Convention on Biological Diversity. We apply these metrics to network scenarios on the northern and equatorial Mid-Atlantic Ridge, where contractors are exploring for seafloor massive sulfide (SMS) deposits. A latitudinally distributed network of areas performs well at (i) capturing ecologically important areas and 30 to 50% of the spreading ridge areas, (ii) replicating representative areas, (iii) maintaining along-ridge population connectivity, and (iv) protecting areas potentially less affected by climate-related changes. Critically, the network design is adaptive, allowing for refinement based on new knowledge and the location of mining sites, provided that design principles and conservation targets are maintained. This framework can be applied along the global mid-ocean ridge system as a precautionary measure to protect biodiversity and ecosystem function from impacts of SMS mining.
The people of Oceania have long relied on the ocean for sustenance, commerce, and cultural identity, which promulgated a sophisticated understanding of the marine environment and its conservation. Global declines in ocean health now require innovative solutions that can benefit from customary knowledge and practices, which in the past led to sustainable marine resource use. The resurgence of local stewardship, which incorporates customary practices and governance, has shown promise in many locations throughout the Pacific, although a complete return to past practices is not fully implementable owing to the loss of traditional knowledge, centralized governmental structures, economic development, and globalization. Hybrid systems that incorporate elements of customary and contemporary management can overcome some of these limitations to implementation of successful local management, and lead to greater food security, social cohesion, and the creation of an adaptive system that can potentially mitigate the effects of climate change and other stressors.
Identifying priority areas for biodiversity conservation is particularly challenging in the marine environment due to the open and dynamic nature of the ocean, the paucity of information on species distribution, and the necessary balance between marine biodiversity conservation and essential supporting services such as seafood provision. We used the Patagonian seabird breeding community as a case study to propose an integrated and adaptive method for delimiting key marine areas for conservation. Priority areas were defined through a free decision‐support tool (Marxan) that included projected at‐sea distributions of seabirds (approximately 2,225,000 individuals of 14 species); BirdLife Important Bird and Biodiversity Areas (IBAs) for pelagic bird species; and the economic costs of potential regulations in fishing practices. The proposed reserve network encompassed approximately 300,000 km2 that was largely concentrated in northern and southern inshore and northern and central offshore regions. This reserve network exceeded the minimum threshold of 20% conservation of the abundance of each species proposed by the World Parks Congress. Based on marine currents in the study area, we further identified the 3 primary water masses that may influence areas of conservation priority through water inflow. Our reserve network may benefit from enhanced marine productivity in these highly connected areas, but they may be threatened by human impacts such as marine pollution. Our method of reserve network design is an important advance with respect to the more classical approaches based on criteria defined for one or a few species and may be particularly useful when information on spatial patterns is data deficient. Our approach also accommodates addition of new information on seabird distribution and population dynamics, human activities, and alterations in the marine environment.
We develop a model for four sustainability paradigms (weak sustainability, a-growth, de-growth, strong sustainability) within a single framework that accounts for responsibility for nature and future generations and for intra- and inter-generational equality. The model is applied in three case studies: the Baltic, the Adriatic and the Black Sea with the aim to identify feasible sustainability solutions for shared seas under alternative sources of environmental pressure and cooperation strategies. The Baltic Sea is analyzed as an example of pollution from agriculture, the Adriatic Sea as an example of over-exploitation of fish in fishery, and the Black Sea as an example of pollution from industry. Empirical results show that different cooperation strategies are feasible in each case and that they yield different results in different context. Also welfare implications vary between different cooperation strategies. The main policy implication of the analysis is two-fold. Environmental conservation must be preferred to environmental innovation, where both intra- and inter-generational equity concerns are unessential. The choice of a different sustainability approaches must be combined with the feasibility of the differently required management institutions, while considerations of the sectoral sources of environmental pressure are essential.