Looking for:
Manta feeder 360 free download. Manta Ray and Free Diver, Manta alfredi, Raja Ampat, West Papua, Indonesia |
Manta feeder 360 free download -
Manta feeder 360 free download
They are targeted or retained for the Asian medicine trade as well as consumption of meat Croll et al. The attraction of mobulids to productive tropical and subtropical habitats where target species such as tunas aggregate, along with their distribution in the epipelagic zone, make them vulnerable to fisheries capture Croll et al.
Mobulids are targeted or caught as bycatch in virtually every fishing gear type, including small-scale fisheries characterized by the use of driftnets, gillnets, harpoons, gaffs, traps, trawls, and longlines; and large-scale fisheries using driftnets, trawls and purse seines Croll et al.
The level of bycatch depends greatly on the fishing method used, with the highest bycatch rates reported from gillnets and purse seiners Croll et al. The slow population growth rates of mobulid populations largely exclude them from considerations of sustainable targeted fisheries Dulvy et al. Consequently, future research should focus on assessing bycatch risks and mitigation efforts as well as the impacts of existing fisheries on mobulid populations.
Figure 5. Mobulid fisheries. Mobulid rays are captured incidentally in virtually all fishing gear types, and are also targeted for their meat and gill plates in some countries.
See section 5. While fisheries regulations have sought to prevent the retention and landing of mobulid rays, the vast majority of mobulid captures are a result of unintentional bycatch Croll et al. Physical and biological traits of rays i. In the past, onboard handling practices have resulted in high levels of post-release mortality Hall and Roman, ; Poisson et al.
Further work to identify and implement less harmful handling practices could prevent a significant amount of onboard mobulid mortality. Evaluating survival rates of mobulids released alive in non-target fisheries will help guide management decisions, as simply banning landings will not be an effective strategy in cases where a high proportion of individuals die after release.
Initial studies of M. Researchers should evaluate the post-release mortality of mobulids captured incidentally in a variety of gear types, as fishing gear such as gill nets with long soak times may have considerably higher post-release mortality rates than long lines or purse seines. Additionally, future studies should evaluate the impact of handling and release methods and relevant environmental and operational covariates on mobulid post-release mortality in order to develop release guidelines that maximize survival.
Post-release mortality can be evaluated using pop-off satellite tags Francis and Jones, or blood chemistry analyses Hutchinson et al. In coastal fisheries where released mobulids are more likely to remain in range of acoustic receivers, researchers could also consider the use of acoustic tags to evaluate survivorship rates Skomal, Accelerometer tags may also be useful in the quantification of post-release behavior and mortality and the impacts of handling methods in cases where instrument recovery is feasible Whitney et al.
As relationships between directly observable covariates e. Identifying areas of overlap between mobulid hotspots and fisheries could help reduce mobulid bycatch rates.
Concurrent satellite tracking of focal species and vessel monitoring systems can provide insights into bycatch risk and identify key locations for mitigation and management action Queiroz et al. Onboard fisheries observers provide far more data-rich scenarios in which to assess bycatch risk, especially in commercial fisheries with high observer coverage such as the IATTC tuna purse seine fleet Hall and Roman, ; Croll et al.
These observer records allow for detailed species distribution models that can reveal relationships between species abundance and key environmental variables, both for bycatch and target species Scales et al. Future studies should identify the regions with both the highest overall mobulid bycatch rates, and the highest mobulid bycatch to target catch ratios.
This information will allow managers to develop spatio-temporal and ideally dynamic management approaches with the greatest ecological and conservation value for mobulids and the lowest economic loss from reduced catches of target species.
However, to take full advantage of fisheries observer data to develop species-specific habitat and distribution models, data collection protocols need to be standardized and species identification training for observers emphasized.
Researchers could work with regional fisheries management organizations RFMOs to develop a comprehensive, standardized data collection manual for mobulids that ensures all relevant variables, including release methods, are collected and can be compared among regions and fisheries. Additionally, RFMOs should be encouraged to implement detailed mobulid identification training courses, and researchers could follow up with molecular identification of captured specimens to determine identification error rates.
Unfortunately, these approaches will not cover mobulid mortality onboard smaller tuna purse seine vessels that don't carry observers, or for fisheries targeting species outside the purview of the current RFMOs e. Many of these vessels operate in nearshore productive waters where mobulids aggregate, and are likely to represent substantial unreported mobulid bycatch. Further research is necessary to describe the nature and quantity of this bycatch e.
Bycatch mitigation methods have not been adequately explored for mobulids, and proposals for preventing interactions between fishing gear and mobulids through technological innovations or gear modifications are needed. Strong associations with the thermocline in M. However, the feasibility of limiting gear depth in commercial fisheries is questionable, and therefore alternate proposals should be developed and tested for mobulids more generally.
Bycatch mitigation has been developed for many non-target marine species such as seabirds in long-line fisheries e. For elasmobranchs more generally, there have been various trials, such as the apparently unsuccessful use of rare-earth metals to deter sharks from baited hooks Jordan et al. Some studies suggest that the use of light-emitting diodes in or near the ultraviolet range may reduce bycatch of elasmobranchs in gill net fisheries Jordan et al.
Although in-depth research into population genetic structure is lacking for mobulids, the limited studies of genetic connectivity indicate that populations are spatially structured Stewart et al. Consequently, fisheries management of mobulid rays may be more effective and relevant at the stock level, rather than simply along political or geographic boundaries Reiss et al.
More genetic studies are needed to identify genetically distinct populations of mobulid rays to support regional management strategies. As traditional gene sequencing methods may not reveal population structure in mobulids Kashiwagi et al. Given that many of the smaller mobulid species are challenging to find and sample in typical field expeditions, fisheries may provide the best opportunities to obtaining such sample representation.
For example, tissue, or tail samples collected by observers in tuna fisheries could provide the extensive geographic coverage and the large sample sizes necessary for investigating genetic connectivity.
Additionally, there is strong evidence for a positive correlation between genetic diversity and a population's resilience to extinction Frankham, ; von der Heyden, and overexploited fish species have been shown to have lower genetic diversity than closely related species that are not overharvested Pinsky and Palumbi, We therefore encourage researchers to evaluate genetic diversity across a gradient of fishing pressure to establish if and where fishing has led to a loss of diversity and population bottlenecks e.
This will help prioritize vulnerable populations for conservation and management action. Studies of general patterns of effective population sizes and descriptions of the demographic histories of mobulids can establish valuable baseline reference points. Understanding the spatial dynamics and habitat use patterns of animal populations is key to successful conservation and management Cooke, ; Ogburn et al.
This theme has been a dominant focus of mobulid ray research over the past decade, with 17 published studies documenting movements of individuals using a combination of photographic mark-recapture methods and electronic tracking. Using acoustic and satellite telemetry, movements of 1, individual rays of 6 species have been investigated in 10 distinct regions throughout their range Figure 6.
Together, these studies highlight the large movement capacity of manta and devil rays and their use of broad geographic ranges including coastal and pelagic waters Croll et al. High rates of site residency and fidelity have been demonstrated, particularly in manta rays Jaine et al.
The drivers underlying these large seasonal aggregations, common to both manta and devil rays, remain elusive. Identifying common physical and biological processes that underlie movements and aggregative behavior across species will allow for improved identification and characterization of critical habitats. Studies of fine-scale habitat use at aggregation sites have revealed that individuals visit these areas to attend shallow cleaning stations, engage in courtship behavior, and forage on ephemeral food resources Dewar et al.
Figure 6. Mobulid telemetry effort to date. The mobulid tagging effort information was sourced from published literature on the topic as well as from other unpublished mobulid tracking studies known to the authors and their collaborators summarized in Table S1. See section 6. Technological advances in satellite tagging Musyl et al. Most studies of mobulid movements have employed pop-up satellite archival transmitting PSAT tags Table S1 , which typically yield long retention times but coarse position estimates i.
Using these, mobulid rays have been successfully tracked for periods of up to a year, revealing regional philopatric movements and strong affinity to shelf edge habitats in manta rays Braun et al.
In contrast, towed Argos-linked tags require long tethers to facilitate surface satellite communications, leading to shorter deployments poor tag retention but higher resolution position estimates whenever the tag surfaces. These have been successfully used to investigate short-term i. More recently, towed tags enabled with fast-acquisition GPS technology e.
Erdmann pers. Fastloc positions require less surface time, allowing for shorter tethers and longer retention times than Argos-linked tags, but do not transmit archived high-resolution GPS positions until the tag detaches from the animal. Recent improvements to geolocation and subsequent state space models are quantifying and reducing the levels of uncertainty associated with light-based geolocation Patterson et al.
It is likely that with the increasing capacity to make fine-scale observations, movement patterns will indicate significant overlap with anthropogenic threats or sensitive areas Braun et al.
Researchers could therefore incorporate metrics such as the Human Impact Index Halpern et al. Fine-scale habitat use assessments will be facilitated by increased use of Argos-linked and Fastloc tags, and researchers could make efforts to improve retention times for these tag types, perhaps by implementing new attachment methods such as dorsal fin mounts e. In addition to contributing important spatial information about the conservation needs of these species, such information will enhance our understanding of the global connectivity of mobulid populations with respect to gene flow and potential isolation.
Compared with satellite tags, the affordability and longer battery life of acoustic tags enables the collection of larger datasets on mobulid movements, site fidelity and habitat use than studies employing satellite tags. The increased battery life of acoustic transmitters up to 10 years will also greatly benefit efforts to monitor site fidelity and residency in mobulid species that are rarely encountered and are often only tagged opportunistically e.
However, the long-term attachment of external tags on mobulid rays over months to years remains a challenge. Future studies should consider internal tagging where possible e. Kessel et al. Additionally, acoustic tags only provide positions when they are in range of acoustic receiver stations, limiting their utility for wide-ranging mobulids that routinely travel outside of receiver arrays. Researchers could make use of collaborative regional acoustic sensor networks to expand monitoring capacity e.
Large scale collaborative efforts will inform the design of management strategies on national or smaller scales Lea et al. The ability of researchers to identify and predict areas of critical habitat for mobulid rays will be improved with increasing amounts of movement data collected through telemetry studies Hays et al. Density maps e. Historical observations of mobulid presence and aggregation events may provide novel and temporal insight into species distributions.
Researchers should consider Unmanned Aerial Vehicle UAV technology or aerial surveys to provide additional opportunities to collect quantitative and behavioral data of mobulids Hodgson et al. It is highly likely that oceanographic features and their influence on the distribution of patchy prey resources play a key role in driving the behavior of planktivores Sims et al.
Studies should include oceanographic and biological information, such as prey field density and frontal systems, in their spatial analyses to expand our current understanding of mobulid movement patterns e. Together, these data can be used in ecosystem niche modeling to identify potential new regions of importance to mobulid species Panigada et al.
The position uncertainty inherent in light-based geolocation tags impedes the incorporation and comparison of oceanographic data with movements as prey fields and oceanographic features can vary widely within the error radius of a single position estimate. Increased use of Argos-linked transmitters with more precise position estimates may facilitate the inclusion of these important physical and biological features into spatial analyses. It is crucial to gain a broader understanding of mobulid habitat use to better understand the effects of anthropogenic activities Graham et al.
Ontogenetic shifts in movements and habitat use are common in elasmobranchs Grubbs, Juvenile mobulids are rarely seen and presumably exhibit size or age segregation until they approach maturity Stewart et al. Consequently, critical habitat use and movements likely vary among life stages in mobulid rays. Future studies could seek to address these ontogenetic differences, in particular by filling knowledge gaps in the movements and habitat use of juvenile and young-of-year mobulids. Ongoing efforts to monitor mobulid movements through photo-ID Kumli and Rubin, ; Couturier et al.
Fortunately, strong collaborative momentum within the scientific community and developments in analytical tools are now allowing for telemetry studies to take place at unprecedented scales, tracking movements of a multitude of marine species across oceans and over several years e. Acoustic and satellite telemetry studies continue to provide insights into the movement and spatial use patterns of mobulids Croll et al. This site and species specificity in combination with limited sample sizes does not sufficiently support our understanding of broad-scale patterns at the population or species level.
We recommend that future studies emphasize multi-species and multi-region tagging efforts to define critical habitats, resolve patterns in movement and connectivity among populations, improve our understanding of species-specific drivers of movement, and support efforts for management and bycatch reduction. Determining drivers of mobulid aggregative and migratory behavior and how they are linked to foraging opportunities can help identify where these species are most susceptible to direct or incidental capture in fisheries Rohner et al.
Mobulids are restricted to tropical and subtropical oceans, which in many regions are oligotrophic and may have lower zooplankton biomass than temperate and polar systems Moriarty and O'Brien, This means that many populations of mobulids must find high biomass food patches in a dilute food environment. Stomach content analysis suggests that mobulids are opportunistic feeders that exploit zooplankton and, sometimes, teleost prey that are available in high densities Figure 7.
For example, in Mexico and the Philippines, several mobulid species M. Similarly, studies evaluating the prey community alongside feeding mobulids showed that M.
Results from studies using stable isotopes and fatty acids as trophic tracers support direct observation data that mobulids are predominantly consumers of zooplankton, but that fishes make up a notable portion of their diet in some regions Sampson et al. Further, some studies have suggested that M. Diving capacities and behaviors of several mobulid species also support the hypothesis that these animals can exploit prey in deep oceanic layers Canese et al.
To help predict spatiotemporal distributions of mobulids, future studies should aim to identify common characteristics among their prey species such as community composition, biomass, size spectra and swimming capacity.
Further, examination of diving capacities of mobulids will provide a better understanding of different foraging strategies across their range and how these are affected by environmental variability e. Knowledge of prey landscapes alongside drivers and types of movement is key to habitat modeling efforts and the implementation of effective conservation measures for mobulids.
Figure 7. Foraging behavior of mobulid rays. The majority of direct observations of foraging are from epipelagic waters. However, a broad range of methods including isotope and fatty acid analysis, archival satellite tagging, stomach content analysis and submersible observations indicate that mesopelagic prey are important diet items for mobulids.
References for this figure are listed in Table S2. See section 7. Understanding oceanographic mechanisms that influence the distribution of mobulids will be important for identifying critical habitats that warrant special protection see section 6. Movements: Critical habitats. However, the temporal lag between primary productivity, which can be observed via satellite, and secondary productivity i.
Incorporating prey e. When possible, researchers should strive to collect prey data concurrently with mobulid sightings and behavioral data McCauley et al. However, in studies using telemetry and fisheries data this may not be feasible. Instead, researchers could take advantage of existing oceanographic datasets with high-resolution prey data e. We encourage researchers to consider what prey data are available at or near their proposed study region, and even to consider specifically targeting regions with large oceanographic datasets for future mobulid research.
Additionally, we encourage researchers to collaborate with oceanographers and cruise planners to help ensure that large-scale zooplankton data collection efforts are most relevant to studies of higher trophic level organisms including mobulids.
Bridging the gap between oceanographic data and mobulid movements and foraging behavior will allow for more robust analyses of distribution, critical habitat use, bycatch risk, and climate impacts.
Given the limitations of temporal coverage in stomach content analyses, a number of studies have employed stable isotope analysis and fatty acid profiling to examine the diet of mobulid rays Sampson et al.
While diet-tissue discrimination values and turnover rates have been examined for several elasmobranchs Hussey et al. Captive feeding experiments on mobulids under controlled conditions in aquaria are needed to evaluate turnover times, diet tissue discrimination factors, and validate the use of other tissue types that can be sampled by non-invasive means for biochemical analyses, such as mucus Burgess et al.
Standardized protocols for sample preservation e. Future biochemical work on mobulid species could also consider compound-specific isotope analysis, a relatively new analytic tool in dietary studies Mcmahon et al. This technique provides a finer resolution on the origin of individual components e. In all isotopic studies, adequate sampling of the food web and candidate diet items identified in observational studies and stomach contents is necessary to parameterize mixing models and quantify dietary contributions Burgess et al.
By combining several biochemical techniques and using large datasets, future studies will bring new understanding on trophic markers resulting from the different analyses and allow for more robust data interpretations on the dynamics of energy transfer in the pelagic environment.
Over the past decade, there has been an increased effort in using tagging technology to assess the vertical movement of mobulids and associated mesopelagic foraging ability. Telemetry studies of other marine megafauna species have identified that the deep scattering layer Goldbogen et al. For mobulid species, all telemetry studies have shown that individuals spend most of their time within the upper 50 m of the water column where the likelihood of encountering fishing gear is greatest.
Several studies suggest that mesopelagic food sources comprise a major part of mobulid diet Burgess et al. Additionally, vertical migrators such as euphausiids and myctophids that appear to be an important prey source for mobulids may allow them to feed on mesopelagic prey sources without accessing mesopelagic environments Burgess et al. Many manta ray aggregation sites are adjacent to shelf breaks, and telemetry data suggest that individuals may depart coastal habitats at night Burgess, ; Couturier et al.
Obtaining new information on mesopelagic prey sources may require targeted field expeditions that sample prey at depth, which can be done with opening-closing nets, or could employ technology such as submersibles Stewart et al. A better understanding of mobulids' reliance on these food sources and habitats will lead to improved characterization of aggregation sites, as well as habitat and species distribution models.
As technology develops, so too does the ability to track and monitor mobulids in remote and deep realms of the ocean. Animal-borne cameras Stewart et al. In studies of the diving behavior of other marine species, accelerometers have been successfully used to remotely assess diving energetics in the whale shark Gleiss et al.
We therefore encourage researchers to apply accelerometers to future studies of mobulid feeding and diving behavior. This will require advances in attachment methods that allow accelerometer orientation to remain stable on mobulids, and exploring options for longer-term deployments and instrument recovery. New sensory systems can also be incorporated into existing telemetry devices.
For example, fluorometers embedded into satellite tags can provide in situ measurements of phytoplankton fluorescence that can be used to calculate chlorophyll- a concentrations and to assess primary productivity levels alongside animal movement data Lander et al. Mobulid rays, as filter feeders, may be susceptible to ingesting marine pollutants and contaminants such as persistent organic pollutants POPs , heavy metals, and microplastics.
Pollutants enter the marine environment through wastewater, poor industry practices, and degradation of marine debris, among other sources. Microplastics contain added pollutants and toxins such as phthalates, bisphenol A, flame retardants, styrenes, and adsorb and concentrate persistent organic pollutants POPs and heavy metals from the marine environment Worm et al.
Many dissolved pollutants are lipophilic, persistent in the environment, and have the capacity to bio accumulate up the food chain, with large bodied, long-lived species at high risk to exposure Niimi, Mobulid habitats, including foraging grounds, overlap with microplastic pollution hotspots in many cases Germanov et al.
However, rates of plastic ingestion by mobulids, bioaccumulation of pollutants, and the impacts of plastic pollution on mobulid biology, ecology, and population viability have not been studied.
Future research should work toward identifying the scale of these problems and quantifying impacts so they can be evaluated in a management context. In locations with high densities of floating microplastics, mobulids may directly ingest microplastics Figure 8. Additionally, zooplankton can be contaminated with pollutants and toxins Fossi et al. This suggests that mobulids may be secondary consumers of microplastics and associated pollutants even if they are foraging in locations or at depths that do not have high densities of floating microplastics.
Future research should seek to quantify ingestion rates of microplastics in mobulids. This could be accomplished by evaluating microplastic densities and contamination in prey assemblages by sampling prey alongside feeding mobulids. Additionally, measuring the abundance of microplastic particles in stomach contents of mobulids landed in fisheries could provide estimates of direct ingestion.
In order to evaluate whether ingestion leads to bioaccumulation in tissues, researchers should measure phthalate, heavy metal, and POP levels in mobulid tissue biopsies from wild populations and samples collected from fisheries. Previous studies found elevated levels of some heavy metals in mobulid tissues Essumang, , ; Ooi et al.
Future research in mobulids could evaluate levels of phthalates, POPs and heavy metals in mobulid tissues across gradients of microplastic pollution to determine how bioaccumulation scales with pollutant levels in the environment and to identify heavily impacted populations.
Sources and aggregating mechanisms of plastic pollution vary between coastal and offshore environments, leading to differing levels of overlap between microplastic hotspots and mobulid habitats Germanov et al. Researchers could investigate differences in pollutant contamination between coastal mobulids e. Once trophic interactions between mobulids and pollutants are better understood, researchers could endeavor to identify high-risk areas for mobulids following existing approaches for other taxa such as sea turtles Schuyler et al.
Figure 8. Sub-lethal impacts on mobulids. Entanglement in fishing gear can cause substantial damage and scarring a , including amputations of cephalic fins and damage to eyes b. The impacts of these stressors on mobulid foraging success, reproductive output, and population viability are poorly studied.
See sections 8 and 9. A number of recent studies have demonstrated that microplastics, POPs and heavy metals impact regular cellular and system functioning, including endocrine disruption, leading to knock-on negative impacts on reproductive output with the potential to alter populations and ecological assemblages of marine species Jakimska et al.
The implications of exposure to pollution and contaminants in mobulids is still speculative, especially at the level of individual fitness and population viability. Demonstrating that mobulids ingest microplastics and other pollutants is important for assessing the extent of these threats, but will be insufficient for evaluating the true impact of pollutants and their importance as a management consideration.
Future studies should seek to quantify the impacts of plastic pollution on mobulids by, for example, comparing pollutant concentrations in the environment and in mobulid tissues with metrics of individual and population health such as body condition, reproductive output, population trends, and individual survival. Studies that compare populations across a pollutant gradient, or evaluate a single population through time as pollutant levels fluctuate could provide insights into the true impacts of plastics and other pollutants and their importance as an emerging management consideration.
Sub-lethal threats such as entanglement, tourism pressure, habitat destruction, and climate change are likely to considerably impact mobulid survival throughout their range Couturier et al. Anthropogenic injuries resulting from foul hooking, entanglement in fishing gear, and boat strikes are evident in every monitored mobulid population across the globe, including severe injuries such as amputation or deformity of cephalic and pectoral fins, and damage to the eyes Deakos et al.
While these threats are known, the extent to which these impacts may affect individual health and overall population fitness is unclear Couturier et al. Mobulid-focused tourism activities are increasingly promoted as a non-consumptive and more sustainable alternative to fishing practices, particularly in developing countries Anderson et al. Potential impacts of unregulated tourism activities at mobulid aggregation sites have been widely recognized.
Initial investigations observed short-term behavioral changes including the termination of feeding or cleaning behaviors during tourism interactions with M. Future research priorities lie in accurately documenting and quantifying sub-lethal stressors, while determining the severity of different types of impacts to prioritize mitigation measures and develop effective management strategies.
For well-studied, resident populations, documenting how well and how quickly injuries heal over time will be informative. Additionally, researchers could track metrics such as body size, growth rates, and pregnancy rates between injured and healthy individuals to determine the impacts of different types of injuries on an individual's fitness. Researchers could evaluate the frequency of injuries in different age classes and sexes in order to characterize ontogenetic variability of impacts.
Comparing differences in the magnitude of the threats among populations of the same species will guide appropriate management strategies or codes of conduct that specifically address local needs and effectively mitigate regional threats. For example, certain populations may more commonly exhibit surface ram feeding to target a preferred food source, subjecting individuals to a greater threat of collision with boats or propeller injuries. Other populations may inhabit an environment littered with fishing nets due to regional fishing practices, creating a greater threat of entanglement.
Proper characterization and quantification of these threats and their individual and population-level impacts is critical for effective, local management of mobulid populations. As the nature and intensity of tourism activities vary considerably among locations, specific aggregation sites and focal species, we recommend site-specific assessments and long-term monitoring of local tourism industries to determine their effect on mobulid populations.
Aerial and underwater drone technology or unmanned stationary cameras could be used as passive observation methods to avoid observers or boats impacting natural behaviors and confounding results e. Visits to cleaning stations provide many perceived benefits to the fitness of visiting clients including parasite removal, wound cleaning and even improved cognitive performance Grutter, ; Binning et al. Future research could aim to determine whether short-term disturbances lead to biologically significant impacts, such as decreased health e.
The implications of tourism activities using artificial lighting to attract plankton Osada, could be tested through long-term comparative studies quantifying growth and pregnancy rates as fitness indicators for individuals that do and do not partake in nighttime feeding activities.
Additionally, telemetry methods can be used to determine if individuals preferentially visit provisioning sites, altering natural behavior Hammerschlag et al. Passive interactions and adherence to a code of conduct have been recommended as precautionary measures to decrease the likelihood of disturbance Garrud, ; Venables et al.
Assessments of the effectiveness of established codes of conduct during different interaction scenarios are essential to refine and improve regulations Murray et al. Habitat destruction and degradation can directly impact species survivorship and responses to environmental change, making it a leading cause of biodiversity loss Dobson et al.
Anthropogenic pressures on coastal environments such as aquaculture, dredging and coastal runoff are potential stressors to marine communities, including pelagic visitors. Coastal reefs in tropical and subtropical waters are preferred habitats for several mobulid species where individuals can show high site fidelity and in some cases long-term residency Marshall and Bennett, ; Deakos et al.
McGregor pers. Lagoon habitats, which may serve as important nursery areas, are especially sensitive to habitat degradation, pollution, and sedimentation McCauley et al. Future research could investigate habitat selectivity of mobulid rays to determine if individuals preferentially occupy and use healthy versus degraded reef habitat, and how these preferences affect behaviors such as feeding, cleaning and socializing.
This information can then be used to inform which regions require additional management actions, such as marine protected areas, or reduction of upstream aquaculture and agricultural activities.
Climate change is expected to cause further disturbances in marine ecosystems, affecting the reproductive biology, abundance and survival of many species. Warming oceans cause changes in ocean acidity, oxygen content, oceanic circulation and primary productivity dynamics, ultimately affecting food web structure and the distribution and availability of mobulid prey Moloney et al.
The major impact of climate change on mobulids is likely to be the projected decline in zooplankton biomass in tropical waters. While it is unknown how this broad-scale decline in zooplankton biomass at the tropics could impacts local areas where mobulids feed, the most likely outcome is that there will be lower zooplankton biomass available for mobulids and other zooplanktivores.
Further work is needed to identify the relative importance of different mobulid feeding environments. For example, if it is confirmed that feeding at the shelf-edge or open ocean on vertically migrating zooplankton from the mesopelagic zone is more important than feeding on zooplankton concentrated by local oceanographic processes around small-scale aggregation sites, then it will be easier to project future changes in zooplankton biomass from biogeochemical models, which are better at projecting large-scale rather than local-scale changes.
In addition to prioritizing critical knowledge gaps, there are several more general considerations that will make the results of future mobulid research most impactful and relevant to management.
Perhaps the most important of these is methodological consistency. We have argued that understanding general patterns of movement, habitat use, and foraging behavior across species and regions will be essential for developing management strategies and mitigating bycatch. In many cases this will require aggregating data across study sites or incorporating previously published data into new studies and analyses.
This becomes increasingly difficult and in some cases impossible when different methodologies have been used to address similar questions. To maximize the utility of future research efforts, researchers should make every effort to coordinate methodological approaches across studies and maintain methodological consistency with previously published studies, even if this means adding complexity to an existing or proposed study.
This may include, for example, standardized measurement methods, tissue collection protocols, sequencing the same genomic regions for comparability across genetic datasets, sample preservation methods for isotope analysis e. In addition, we recommend the development of guidelines for standardized capture and handling protocols to minimize stress to animals and maximize sampling efficiency.
Achieving this will require improved and ongoing communication among research groups and would benefit from a coordinated effort or working group aimed at creating standardized research protocols. Second, long-term data sets are critical for answering many pressing questions about mobulid ecology and biology.
For example, multi-year or multi-decadal telemetry datasets are required to understand interannual variability and environmental drivers of movements and habitat use in mobulids.
For such long-lived animals, long-term ideally multi-decadal photo-ID databases are necessary to accurately estimate key parameters such as survival and fecundity, and to capture the variability that is important for stochastic population projection models. We encourage researchers to make every effort to continue long-running research programs that have the potential to answer key questions proposed in this paper, even at the expense of initiating new projects.
There are many situations where multiple research groups working in the same region may be able to pool resources to maintain key project areas for extended periods. Finally, to make their work directly applicable to regional management actions, researchers should involve resource managers in planning discussions and even research activities where applicable.
Management priorities will vary by region, and having an understanding of local needs and knowledge gaps will help guide research programs and maximize their efficacy. We encourage newcomers and established experts in the field of mobulid research to use the priority areas outlined in this paper as a roadmap for future research activities. However, this should be adapted to local and regional management needs and will depend greatly on the specimens and study systems available. We believe that if progress is made in these research areas over the next decade, it will result in significant contributions to the management and conservation of these threatened species.
BL led the Life history section. CD led the Population trends section. SV led the Sub-lethal impacts section. All authors contributed to writing and editing the manuscript. DF was affiliated with Blue Resources Trust. The remaining 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 Manta Trust supported publishing fees for this open access article. Adnet, S. Evolutionary history of the devilrays Chondrichthyes: Myliobatiformes from fossil and morphological inference. Agnew, D. Estimating the worldwide extent of illegal fishing. Alfaro-Cordova, E. Captures of manta and devil rays by small-scale gillnet fisheries in northern Peru.
Anderson, R. Extent and economic value of manta ray watching in Maldives. Andrzejaczek, S. Temperature and the vertical movements of oceanic whitetip sharks, Carcharhinus longimanus. The ecological connectivity of whale shark aggregations in the Indian Ocean: a photo-identification approach. Open Sci. Armstrong, A. Prey density threshold and tidal influence on reef manta ray foraging at an aggregation site on the Great Barrier Reef. Bailleul, F. Dissolved oxygen sensor in animal-borne instruments: an innovation for monitoring the health of oceans and investigating the functioning of marine ecosystems.
Bec, A. Assessing the reliability of fatty acid-specific stable isotope analysis for trophic studies. Methods Ecol Evol. Bejder, L. Decline in relative abundance of bottlenose dolphins exposed to long-term disturbance.
Beverton, R. Google Scholar. Bigelow, H. Fishes of the western North Atlantic. Sawfishes, guitarfishes, skates, rays, and chimaeroids. Binning, S.
Cleaner wrasse indirectly affect the cognitive performance of a damselfish through ectoparasite removal. B Bograd, S. Deep-sea Res. II Top. Bonney, R. Citizen science: a developing tool for expanding science knowledge and scientific literacy. BioScience 59, — Braun, C. HMMoce: an R package for improved geolocation of archival-tagged fishes using a hidden Markov method.
Methods Ecol. Diving behavior of the reef manta ray links coral reefs with adjacent deep pelagic habitats. Movements of the reef manta ray Manta alfredi in the Red Sea using satellite and acoustic telemetry. Bravington, M. Absolute abundance of southern bluefin tuna estimated by close-kin mark-recapture. Close-Kin Mark-Recapture. Broadhurst, M. Reproductive biology and range extension for Mobula kuhlii cf. Endanger Species Res. Brodie, S.
Integrating dynamic subsurface habitat metrics into species distribution models. C, et al. Continental-scale animal tracking reveals functional movement classes across marine taxa. Bryan, J. Estimation of gonad volume, fecundity, and reproductive stage of shovelnose sturgeon using sonography and endoscopy with application to the endangered pallid sturgeon.
Burgess, K. Manta birostris, predator of the deep? Novel signature fatty acid profile of the giant manta ray suggests reliance on an uncharacterised mesopelagic food source low in polyunsaturated fatty acids. Use of epidermal mucus in elasmobranch stable isotope studies: a pilot study using the giant manta ray Manta birostris.
Freshwater Res. Cadenat, J. Notes d'Ichthyologie ouest-africaine. Cailliet, G. Age and growth studies of chondrichthyan fishes: the need for consistency in terminology, verification, validation, and growth function fitting. Fishes 77, — Campana, S. Bomb dating and age determination of large pelagic sharks. Canese, S.
Diving behavior of the giant devil ray in the Mediterranean Sea. Endangered Species Res. Carlisle, A. Influence of temperature and oxygen on the distribution of blue marlin Makaira nigricans in the Central Pacific. Carrier, J. Assessing reproductive potential and gestation in nurse sharks Ginglymostoma cirratum using ultrasonography and endoscopy: an example of bridging the gap between field research and captive studies.
Zoo Biol. Catchen, J. Stacks: an analysis tool set for population genomics. Chapman, D. There are two effects that water has on light that is important to understand. Firstly, since water is more dense than air, light does not travel as well in water. The result of this is that the deeper you go, the darker the environment you have to work with becomes. This will cause a significant loss in certain colours. The first one to diminish would be the red one, while the blue and the green will pop up.
Something you might have noticed when going scuba diving. It is the way you design how and where you put your subject marine life in the frame, as well as what to have in the background and foreground.
For example, if you are taking a photo of a fish you should choose a simple background so that your subject can be in the centre of attention, rather than having it in front of a crowded background with other objects with similar colours. Choosing what camera to get can be a difficult task. Getting an expensive, high-end camera will no doubt give you a powerful solution.
On the other hand, in order to be able to fully utilize its potential, you need to get familiar with all features and details. A more budget-friendly, point-and-shoot camera will do most of the job for you when it comes to settings and colour balance. Flexi Articulated Butterfly Free.
Stackable Planter mm Free. Vase 03 Free. Ben Affleck Batarang Free. Napkin Holder Laser Cut Free. Vase 01 Free. Flexi Articulated Soaring Eagle Free. Cookie Cutter Moose 2x1 Free. Cookie Cutters Mittens 4x2 Free. Ender 3 Filament guide with 3d printed bearing Free. Euro Coin Dispenser Free. Pedestal v2 Free. Spotify code - Customizable Free.
Comments
Post a Comment