Manta Ray

The capture of leopard whipray, Himantura leoparda Manjaji-Matsumoto & Last, 2008 from the Syrian coast is reported in the present paper. This capture constitutes the first record for the Syrian coast and the third for the Mediterranean Sea. The Syrian specimen measured 2955 mm in total length (TL), 1310 mm disc width (DW), and weighed 54 kg for total body weight. It was a pregnant female carrying 5 developing embryos expulsed from the female on the landing site. The specimen is described and comments on the distribution and the real status of this species in the area are provided.

Understanding variations in habitat use through time contributes to identification of habitats critical for species survival. Here we used passive acoustic telemetry to examine the residency and site fidelity patterns of the reef manta ray Mobula alfredi at Lady Elliot Island (LEI), a key aggregation site in eastern Australia. Six acoustic receivers were moored around LEI between 2009 and 2012, and 34 acoustic transmitters were deployed on manta rays. All tagged animals returned to this site within their recording period, with some individuals visiting the area for up to 23 consecutive days. Using a set of mixed effect models, we analysed the hourly visitation patterns of manta rays in relation to temporal and environmental variables. Diel phase and sea temperature showed the strongest effects on the presence of manta rays, with weaker effects detected for wind direction, wind speed and moon illumination. Individuals occupied LEI habitat mostly during daylight hours and in calm weather conditions, which may be linked with behavioural thermoregulation, social interactions and cleaning activities. Their absence at night may be related to foraging strategies in deeper offshore waters. The effect of sea temperature reflects the greater seasonal occurrence of manta rays at LEI in winter, when temperatures are coolest, potentially in response to regional food availability. The high degree of manta ray site fidelity at aggregation sites underscores the importance of these areas as key daytime habitats for the species. We suggest that conservation measures should prioritise the protection of coastal aggregation habitats from overexploitation and degradation.

Research into the movement ecology of terrestrial and marine animals is growing globally, especially for threatened species. Understanding how far an animal can move and the extent of its range can inform conservation planning and management. On the east coast of Australia, reef manta rays Mobula alfredi are the subject of a photographic identification study, Project Manta. In June 2018, videos of reef manta rays from the SS Yongala (19.31°S, 147.62°E), were submitted to the Project Manta east coast sightings database. The videos were of two individuals previously identified from North Stradbroke Island (27.42°S, 153.55°E), about 1150 km to the south of the SS Yongala. This represents the greatest point-to-point distance travelled by individual M. afredi and extends the latitudinal range for this sub-population on the east coast. This study highlights that citizen science input can provide valuable data to address knowledge gaps in the distribution and population range of marine species. Knowledge of the 1000+ km range movement potential of individual M. alfredi, highlights the possibility that regional sub-populations may span jurisdictional zones of more countries than previously considered likely, complicating conservation management of this species.

Large tropical and sub-tropical marine animals must meet their energetic requirements in a largely oligotrophic environment. Many planktivorous elasmobranchs, whose thermal ecologies prevent foraging in nutrient-rich polar waters, aggregate seasonally at predictable locations throughout tropical oceans where they are observed feeding. Here we investigate the foraging and oceanographic environment around Lady Elliot Island, a known aggregation site for reef manta rays Manta alfredi in the southern Great Barrier Reef. The foraging behaviour of reef manta rays was analysed in relation to zooplankton populations and local oceanography, and compared to long-term sighting records of reef manta rays from the dive operator on the island. Reef manta rays fed at Lady Elliot Island when zooplankton biomass and abundance were significantly higher than other times. The critical prey density threshold that triggered feeding was 11.2 mg m-3 while zooplankton size had no significant effect on feedi...

Understanding variations in habitat use through time contributes to identification of habitats critical for species survival. Here we used passive acoustic telemetry to examine the residency and site fidelity patterns of the reef manta ray Mobula alfredi at Lady Elliot Island (LEI), a key aggregation site in eastern Australia. Six acoustic receivers were moored around LEI between 2009 and 2012, and 34 acoustic transmitters were deployed on manta rays. All tagged animals returned to this site within their recording period, with some individuals visiting the area for up to 23 consecutive days. Using a set of mixed effect models, we analysed the hourly visitation patterns of manta rays in relation to temporal and environmental variables. Diel phase and sea temperature showed the strongest effects on the presence of manta rays, with weaker effects detected for wind direction, wind speed and moon illumination. Individuals occupied LEI habitat mostly during daylight hours and in calm weather conditions, which may be linked with behavioural thermoregulation, social interactions and cleaning activities. Their absence at night may be related to foraging strategies in deeper offshore waters. The effect of sea temperature reflects the greater seasonal occurrence of manta rays at LEI in winter, when temperatures are coolest, potentially in response to regional food availability. The high degree of manta ray site fidelity at aggregation sites underscores the importance of these areas as key daytime habitats for the species. We suggest that conservation measures should prioritise the protection of coastal aggregation habitats from overexploitation and degradation.

In the original version of this Article, the European Commission was mistakenly included as an affiliation for Christos D. Maravelias. His contribution to this work was exclusively completed while at the Hellenic Centre for Marine Research. All versions of the Article have been corrected.

Biomimetics aims to take inspiration from nature and develop new models and efficient systems for a sustainable future. Bioinspired underwater robotics help develop future submarines that will navigate through the water using flexible propulsor. This research has focused on the Manta Ray species as batoid has a unique advantage over other species. This study also aims to improve AUV (Autonomous Underwater Vehicle) efficiency through biomimetic design, the purpose of which is to observe and study the marine environment, be it for sea exploration or navigation. The design and prototyping process of bioinspired AUVs have been mentioned in this study, along with testing a propulsive mechanism for efficient swimming and turning capabilities. The Robot was designed taking structural considerations from the actual Manta-Ray locomotion and body design. The propulsion mechanism and control circuit were then implemented on the developed systems. The prototype of the Manta Ray was able to gene...

The behaviour and spatial use patterns of juvenile manta rays within their critical nursery habitats remain largely undocumented. Here, we report on the horizontal movements and residency of juvenile reef manta rays (Mobula alfredi) at a recently discovered nursery site in the Wayag lagoon, Raja Ampat, Indonesia. Using a multi-disciplinary approach, we provide further corroborative evidence that the lagoon serves as an important M. alfredi nursery. A total of 34 juvenile rays were photo-identified from 47 sightings in the sheltered nursery between 2013–2021. Five (14.7%) of these individuals were resighted for at least 486 days (~1.3 years), including two juveniles resighted after 641 and 649 days (~1.7 years), still using the nursery. Visually estimated (n=34) disc widths (DW) of juveniles using the nursery site ranged from 150–240 cm (mean ± SD: 199 ± 19), and the DW of two juveniles measured using drones were 218 and 219 cm. Five juveniles were tracked using GPS-enabled satellite...

Functional properties of shark denticles have caught the attention of engineers and scientist today due to the hydrodynamic effects of its skin surface roughness. The skin of a fast swimming shark reveals riblet structures that help to reduce skin friction drag, shear stresses, making its movement to be more efficient and faster. Inspired by the structure of the shark skin denticles, our team has conducted a study on alternative on improving the hydrodynamic design of marine vessels by applying the simplified version of shark skin skin denticles on the surface hull of the vessels. Models used for this study are constructed and computational fluid dynamic (CFD) simulations are then carried out to predict the effectiveness of the hydrodynamic effects of the biomimetic shark skins on those models. Interestingly, the numerical calculated results obtained shows that the presence of biomimetic shark skin implemented on the vessels give improvements in the maximum speed as well as reducing the drag force experience by the vessels. The pattern of the wave generated post cruising area behind the vessels can also be observed to reduce the wakes and eddies. Theoretically, reduction of drag force provides a more efficient vessel with a better cruising speed. To further improve on this study, the authors are now actively arranging an experimental procedure in order to verify the numerical results obtained by CFD. The experimental test will be carried out using an 8 metre flow channel provided by University Malaysia Sarawak, Malaysia.

Seagrass meadows are an important component of coastal ecosystems globally, and they capture and store organic carbon in living biomass and sediments. Geographical estimates of blue carbon in seagrass habitats are regionally biased, with limited information from the Indo-Pacific region, including Indonesia. Seagrass extent in Indonesia is declining rapidly, and it has been suggested that marine protected areas (MPAs) are an important instrument to support protection of seagrass ecosystems and their services. Thus, this study is aimed at quantifying and comparing sedimentary carbon stocks and sources of organic carbon from seagrass meadows located in undisturbed areas outside MPA, disturbed areas outside MPA, and within MPA in three small islands in Indonesia. The sediment carbon stocks from this study ranged from 19.81 to 117.49 Mg C ha−1, with the highest stock measured inside MPA (77.15 ± 1.38 Mg C ha−1), followed by undisturbed outside MPA (36.08 Mg C ha−1), and the lowest stock ...

The world is facing the global trend of Industry 4.0 in the manufacturing sectors. The concept of the Internet of Underwater Thing (IoUT) presents the trends in the underwater region. The Autonomous Underwater Vehicle (AUV) as a data collector and transmitter becomes the central component in the connected system of the IoUT. The efficiency of the platform is crucial to lengthening the range and duration of the mission. The biomimetic method of utilizing the caudal fin propulsion could enhance the efficiency of the small and low-speed AUV. From the defense perspective, there is a concept of Revolution in Military Affairs (RMA) that supports technological modernization for defense purposes. Technically, this study aims to combine the technical aspects of mechanical engineering and the defense concept of RMA in the technological advancement of AUV for the advanced and efficient defense strategy in the underwater region. The evaluations involved numerical simulation with Computational F...

The known distribution of manta rays in Australian waters is patchy, with records primarily centred around tourism hotspots. We collated 11,614 records of M. alfredi from photo-ID databases (n= 10,715), aerial surveys (n= 378) and online reports (n= 521). The study confirms an uninterrupted coastal distribution from north of 26°S and 31°S on the west and east coasts respectively. More southerly M. alfredi records relate to warm-water events with a southernmost extent at 34°S. Coastal sightings of M. birostris were rare (n= 32), likely reflecting a preference for offshore waters, but encompass a wider latitudinal extent than M. alfredi of 10-40°S.

The behaviour and spatial use patterns of juvenile manta rays within their critical nursery habitats remain largely undocumented. Here, we report on the horizontal movements and residency of juvenile reef manta rays (Mobula alfredi) at a recently discovered nursery site in the Wayag lagoon, Raja Ampat, Indonesia. Using a multi-disciplinary approach, we provide further corroborative evidence that the lagoon serves as an important M. alfredi nursery. A total of 34 juvenile rays were photo-identified from 47 sightings in the sheltered nursery between 2013–2021. Five (14.7%) of these individuals were resighted for at least 486 days (~1.3 years), including two juveniles resighted after 641 and 649 days (~1.7 years), still using the nursery. Visually estimated (n=34) disc widths (DW) of juveniles using the nursery site ranged from 150–240 cm (mean ± SD: 199 ± 19), and the DW of two juveniles measured using drones were 218 and 219 cm. Five juveniles were tracked using GPS-enabled satellite...

The behaviour and spatial use patterns of juvenile manta rays within their critical nursery habitats remain largely undocumented. Here, we report on the horizontal movements and residency of juvenile reef manta rays (Mobula alfredi) at a recently discovered nursery site in the Wayag lagoon, Raja Ampat, Indonesia. Using a multidisciplinary approach, we provide further corroborative evidence that the lagoon serves as an important M. alfredi nursery. A total of 34 juvenile rays were photo-identified from 47 sightings in the sheltered nursery between 2013-2021. Five (14.7%) of these individuals were resighted for at least 486 days (~1.3 years), including two juveniles resighted after 641 and 649 days (~1.7 years), still using the nursery. Visually estimated (n=34) disc widths (DW) of juveniles using the nursery site ranged from 150-240 cm (mean ± SD: 199 ± 19), and the DW of two juveniles measured using drones were 218 and 219 cm. Five juveniles were tracked using GPS-enabled satellite transmitters for 12-69 days (mean ± SD: 37 ± 22) in 2015 and 2017, and nine juveniles were tracked using passive acoustic transmitters for 69-439 days (mean ± SD: 182 ± 109) from May 2019-September 2021. Satellite-tracked individuals exhibited restricted movements within Wayag lagoon. The minimum core activity space (50% Utilisation Distribution-UD) estimated for these five individuals ranged from 1.1-181.8 km 2 and the extent of activity space (95% UD) between 5.3-1,195.4 km 2 in area. All acoustically tagged individuals displayed high residency within the nursery area, with no acoustic detections recorded outside the lagoon in the broader Raja Ampat region. These juveniles were detected by receivers in the lagoon throughout the 24 h diel cycle, with more detections recorded at night and different patterns of spatial use of the lagoon between day and night. The observed long-term residency of juvenile M. alfredi provides further compelling evidence that the Wayag lagoon is an important nursery area for this globally vulnerable species. These important findings have been used to underpin the formulation of management strategies to

Populations of mobulid rays are declining globally through a combination of directed fisheries and indirect anthropogenic threats. Understanding the movement ecology of these rays remains an important priority for devising appropriate conservation measures throughout the world's oceans. We

Captures of 11 spinetail devil rays, Mobula japanica (Müller et Henle, 1841), from the northern coast of Tunisian (central Mediterranean) are reported in the present paper. Of these 11 specimens, fi ve specimens were described. These captures constitute the fi rst records of the species in the Tunisian waters, but also in the Mediterranean Sea, extending its distribution. This unusual occurrence of M. japanica is probably due to a migration from the eastern tropical Atlantic into the Mediterranean Sea through the Strait of Gibraltar.

Manta rays forage for zooplankton in tropical and subtropical marine environments, which are generally nutrient-poor. Feeding often occurs at predictable locations where these large, mobile cartilaginous fishes congregate to exploit ephemeral productivity hotspots. Investigating the zooplankton dynamics that lead to such feeding aggregations remains a key question for understanding their movement ecology. The aim of this study is to investigate the feeding environment at the largest known aggregation for reef manta rays Mobula alfredi in the world. We sampled zooplankton throughout the tidal cycle, and recorded M. alfredi activity and behaviour, alongside environmental variables at Hanifaru Bay, Maldives. We constructed generalised linear models to investigate possible relationships between zooplankton dynamics, environmental parameters, and how they influenced M. alfredi abundance, behaviour, and foraging strategies. Zooplankton biomass changed rapidly throughout the tidal cycle, a...

Functional properties of shark denticles have caught the attention of engineers and scientist today due to the hydrodynamic effects of its skin surface roughness. The skin of a fast swimming shark reveals riblet structures that help to reduce skin friction drag, shear stresses, making its movement to be more efficient and faster. Inspired by the structure of the shark skin denticles, our team has conducted a study on alternative on improving the hydrodynamic design of marine vessels by applying the simplified version of shark skin skin denticles on the surface hull of the vessels. Models used for this study are constructed and computational fluid dynamic (CFD) simulations are then carried out to predict the effectiveness of the hydrodynamic effects of the biomimetic shark skins on those models. Interestingly, the numerical calculated results obtained shows that the presence of biomimetic shark skin implemented on the vessels give improvements in the maximum speed as well as reducing the drag force experience by the vessels. The pattern of the wave generated post cruising area behind the vessels can also be observed to reduce the wakes and eddies. Theoretically, reduction of drag force provides a more efficient vessel with a better cruising speed. To further improve on this study, the authors are now actively arranging an experimental procedure in order to verify the numerical results obtained by CFD. The experimental test will be carried out using an 8 metre flow channel provided by University Malaysia Sarawak, Malaysia.

Functional properties of shark denticles have caught the attention of engineers and scientist today due to the hydrodynamic effects of its skin surface roughness. The skin of a fast swimming shark reveals riblet structures that help to reduce skin friction drag, shear stresses, making its movement to be more efficient and faster. Inspired by the structure of the shark skin denticles, our team has conducted a study on alternative on improving the hydrodynamic design of marine vessels by applying the simplified version of shark skin skin denticles on the surface hull of the vessels. Models used for this study are constructed and computational fluid dynamic (CFD) simulations are then carried out to predict the effectiveness of the hydrodynamic effects of the biomimetic shark skins on those models. Interestingly, the numerical calculated results obtained shows that the presence of biomimetic shark skin implemented on the vessels give improvements in the maximum speed as well as reducing the drag force experience by the vessels. The pattern of the wave generated post cruising area behind the vessels can also be observed to reduce the wakes and eddies. Theoretically, reduction of drag force provides a more efficient vessel with a better cruising speed. To further improve on this study, the authors are now actively arranging an experimental procedure in order to verify the numerical results obtained by CFD. The experimental test will be carried out using an 8 metre flow channel provided by University Malaysia Sarawak, Malaysia.

Functional properties of shark denticles have caught the attention of engineers and scientist today due to the hydrodynamic effects of its skin surface roughness. The skin of a fast swimming shark reveals riblet structures that help to reduce skin friction drag, shear stresses, making its movement to be more efficient and faster. Inspired by the structure of the shark skin denticles, our team has conducted a study on alternative on improving the hydrodynamic design of marine vessels by applying the simplified version of shark skin skin denticles on the surface hull of the vessels. Models used for this study are constructed and computational fluid dynamic (CFD) simulations are then carried out to predict the effectiveness of the hydrodynamic effects of the biomimetic shark skins on those models. Interestingly, the numerical calculated results obtained shows that the presence of biomimetic shark skin implemented on the vessels give improvements in the maximum speed as well as reducing the drag force experience by the vessels. The pattern of the wave generated post cruising area behind the vessels can also be observed to reduce the wakes and eddies. Theoretically, reduction of drag force provides a more efficient vessel with a better cruising speed. To further improve on this study, the authors are now actively arranging an experimental procedure in order to verify the numerical results obtained by CFD. The experimental test will be carried out using an 8 metre flow channel provided by University Malaysia Sarawak, Malaysia.

Functional properties of shark denticles have caught the attention of engineers and scientist today due to the hydrodynamic effects of its skin surface roughness. The skin of a fast swimming shark reveals riblet structures that help to reduce skin friction drag, shear stresses, making its movement to be more efficient and faster. Inspired by the structure of the shark skin denticles, our team has conducted a study on alternative on improving the hydrodynamic design of marine vessels by applying the simplified version of shark skin skin denticles on the surface hull of the vessels. Models used for this study are constructed and computational fluid dynamic (CFD) simulations are then carried out to predict the effectiveness of the hydrodynamic effects of the biomimetic shark skins on those models. Interestingly, the numerical calculated results obtained shows that the presence of biomimetic shark skin implemented on the vessels give improvements in the maximum speed as well as reducing the drag force experience by the vessels. The pattern of the wave generated post cruising area behind the vessels can also be observed to reduce the wakes and eddies. Theoretically, reduction of drag force provides a more efficient vessel with a better cruising speed. To further improve on this study, the authors are now actively arranging an experimental procedure in order to verify the numerical results obtained by CFD. The experimental test will be carried out using an 8 metre flow channel provided by University Malaysia Sarawak, Malaysia.

Manta ray populations worldwide are vulnerable to sublethal injuries resulting from human activities, e.g., entanglement in fishing line and boat strikes, which have the potential to impact an individual’s health, fitness, and behaviour. Sublethal injuries and physical abnormalities also occur naturally from predation events, deformity, parasites, and disease. To determine the type and frequency of anthropogenic and natural originated injury events affecting Mobula alfredi and M. birostris in the Maldives, we examined data from the Manta Trust’s Maldivian Manta Ray Project (MMRP) database, which contains 73,638 photo-identification (photo-ID) sightings of the two manta ray species from 1987 to 2019. The likely origin of each injury or physical abnormality was determined based on visual assessment of the photo-ID images. Multiple injuries to an individual originating from the same event were grouped for analysis. Generalised linear mixed models (GLMM) were used to investigate the rel...

The Savu Sea, one of Indonesia's top conservation priorities, is home to various marine charismatic species, including the oceanic manta ray (Mobula birostris), whose conservation status is currently endangered and is protected by the Indonesian government. However, due to domestic and global demand for its fishery products, as well as shortcomings in fisheries management, this species is still poached and bycaught in the Savu Sea. Understanding their population structure is important to achieve effective conservation and fisheries management strategies that will have a positive impact on preserving their population in this area. This study aims to reveal the genetic variation of oceanic manta rays in the Savu Sea. Thirty samples from three locations in the Savu Sea were successfully preserved from East Flores (24), West Manggarai (4), and Rote Ndao (2) and then analyzed using ND5 locus from Mithocondiral DNA (mtDNA). The result indicated a close genetic relationship between three locations (East Flores, West Manggarai, and Rote Ndao) based on the phylogenetic tree and Analysis of Molecular Variance (AMOVA) result with value of 0.05158 (P-value = 0.62268) indicated as a single population. In conclusion, the findings of this study provide some insight into the possibility of manta ray populations in the Savu Sea having strong connectivity between areas, which is critical information for regulators and managers to integrate conservation and management strategies within the Savu Sea.

The world is facing the global trend of Industry 4.0 in the manufacturing sectors. The concept of the Internet of Underwater Thing (IoUT) presents the trends in the underwater region. The Autonomous Underwater Vehicle (AUV) as a data collector and transmitter becomes the central component in the connected system of the IoUT. The efficiency of the platform is crucial to lengthening the range and duration of the mission. The biomimetic method of utilizing the caudal fin propulsion could enhance the efficiency of the small and low-speed AUV. From the defense perspective, there is a concept of Revolution in Military Affairs (RMA) that supports technological modernization for defense purposes. Technically, this study aims to combine the technical aspects of mechanical engineering and the defense concept of RMA in the technological advancement of AUV for the advanced and efficient defense strategy in the underwater region. The evaluations involved numerical simulation with Computational F...

ABSTRACThis research aims to provide knowledge and skills to the people of Botubarani Village with an approach to solve local problems with problem-solving techniques through design thinking. The output targets of this program include the opportunity for independent study program students certified as independent campuses to analyze problems that exist in the community related to ecotourism. The implementation method in this activity is Focus Group Discussion (FGD) between field supervisors and students with partner groups and the community. Conduct direct observations together with partners and document the potential that will be developed with the assisted communities in Botubarani Village. Designing program implementation scenarios, conducting training and mentoring for the utilization of waste.Ecotourism problems in the village of Botubarani were discussed by a team of writers using the Customer validation technique. The results of interviews with tourists and customers will the...

This report presents the development of a fluid-structure interaction model using commercial Computational fluid dynamics software and in-house developed User Defined Function to simulate the motion of a trout Department of Mechanical Engineering, Widener University holding station in a moving water stream. The oscillation model used in this study is based on the observations of trout swimming in a respirometry tank in a laboratory experiment. The numerical simulations showed results that are consistent with laboratory observations of a trout holding station in the tank without obstruction and trout entrained to the side of the cylindrical obstruction. This paper will be helpful in the development of numerical models for the hydrodynamic analysis of bioinspired unmanned underwater vehicle systems.

Functional properties of shark denticles have caught the attention of engineers and scientist today due to the hydrodynamic effects of its skin surface roughness. The skin of a fast swimming shark reveals riblet structures that help to reduce skin friction drag, shear stresses, making its movement to be more efficient and faster. Inspired by the structure of the shark skin denticles, our team has conducted a study on alternative on improving the hydrodynamic design of marine vessels by applying the simplified version of shark skin skin denticles on the surface hull of the vessels. Models used for this study are constructed and computational fluid dynamic (CFD) simulations are then carried out to predict the effectiveness of the hydrodynamic effects of the biomimetic shark skins on those models. Interestingly, the numerical calculated results obtained shows that the presence of biomimetic shark skin implemented on the vessels give improvements in the maximum speed as well as reducing the drag force experience by the vessels. The pattern of the wave generated post cruising area behind the vessels can also be observed to reduce the wakes and eddies. Theoretically, reduction of drag force provides a more efficient vessel with a better cruising speed. To further improve on this study, the authors are now actively arranging an experimental procedure in order to verify the numerical results obtained by CFD. The experimental test will be carried out using an 8 metre flow channel provided by University Malaysia Sarawak, Malaysia.

The Savu Sea, one of Indonesia's top conservation priorities, is home to various marine charismatic species, including the oceanic manta ray (Mobula birostris), whose conservation status is currently endangered and is protected by the Indonesian government. However, due to domestic and global demand for its fishery products, as well as shortcomings in fisheries management, this species is still poached and bycaught in the Savu Sea. Understanding their population structure is important to achieve effective conservation and fisheries management strategies that will have a positive impact on preserving their population in this area. This study aims to reveal the genetic variation of oceanic manta rays in the Savu Sea. Thirty samples from three locations in the Savu Sea were successfully preserved from East Flores (24), West Manggarai (4), and Rote Ndao (2) and then analyzed using ND5 locus from Mithocondiral DNA (mtDNA). The result indicated a close genetic relationship between three locations (East Flores, West Manggarai, and Rote Ndao) based on the phylogenetic tree and Analysis of Molecular Variance (AMOVA) result with value of 0.05158 (P-value = 0.62268) indicated as a single population. In conclusion, the findings of this study provide some insight into the possibility of manta ray populations in the Savu Sea having strong connectivity between areas, which is critical information for regulators and managers to integrate conservation and management strategies within the Savu Sea.

Beginning around 2014, some significant changes in the livelihoods among many younger men from the Island of Balobaloang, South Sulawesi, Indonesia, emerged.  This study describes and explains how it is that approximately 50 working-age adult men (out of a total population of about 900) have turned away from interisland shipping and trade and artisanal fishing and toward wage employment aboard tourist ships, working out of distant ports in Indonesia.  This case study uses a qualitative approach to explore and describe the socio-economic life of community members on the island village of Greater Balobaloang as they continue to be affected by economic and environmental changes.  Field data collection was carried out through observation, government documents, and in-depth interviews with respondents.  In particular, this study focuses on the adaptive strategies of younger men as opportunities for making a living have shifted in recent years away from artisanal fishing and interisland s...

ABSTRACThis research aims to provide knowledge and skills to the people of Botubarani Village with an approach to solve local problems with problem-solving techniques through design thinking. The output targets of this program include the opportunity for independent study program students certified as independent campuses to analyze problems that exist in the community related to ecotourism. The implementation method in this activity is Focus Group Discussion (FGD) between field supervisors and students with partner groups and the community. Conduct direct observations together with partners and document the potential that will be developed with the assisted communities in Botubarani Village. Designing program implementation scenarios, conducting training and mentoring for the utilization of waste.Ecotourism problems in the village of Botubarani were discussed by a team of writers using the Customer validation technique. The results of interviews with tourists and customers will the...

Large tropical and sub-tropical marine animals must meet their energetic requirements in a largely oligotrophic environment. Many planktivorous elasmobranchs, whose thermal ecologies prevent foraging in nutrient-rich polar waters, aggregate seasonally at predictable locations throughout tropical oceans where they are observed feeding. Here we investigate the foraging and oceanographic environment around Lady Elliot Island, a known aggregation site for reef manta rays Manta alfredi in the southern Great Barrier Reef. The foraging behaviour of reef manta rays was analysed in relation to zooplankton populations and local oceanography, and compared to long-term sighting records of reef manta rays from the dive operator on the island. Reef manta rays fed at Lady Elliot Island when zooplankton biomass and abundance were significantly higher than other times. The critical prey density threshold that triggered feeding was 11.2 mg m-3 while zooplankton size had no significant effect on feedi...

Manta rays forage for zooplankton in tropical and subtropical marine environments, which are generally nutrient-poor. Feeding often occurs at predictable locations where these large, mobile cartilaginous fishes congregate to exploit ephemeral productivity hotspots. Investigating the zooplankton dynamics that lead to such feeding aggregations remains a key question for understanding their movement ecology. The aim of this study is to investigate the feeding environment at the largest known aggregation for reef manta rays Mobula alfredi in the world. We sampled zooplankton throughout the tidal cycle, and recorded M. alfredi activity and behaviour, alongside environmental variables at Hanifaru Bay, Maldives. We constructed generalised linear models to investigate possible relationships between zooplankton dynamics, environmental parameters, and how they influenced M. alfredi abundance, behaviour, and foraging strategies. Zooplankton biomass changed rapidly throughout the tidal cycle, and M. alfredi feeding events were significantly related to high zooplankton biomass. Mobula alfredi switched from non-feeding to feeding behaviour at a prey density threshold of 53.7 mg dry mass m-3 ; more than double the calculated density estimates needed to theoretically meet their metabolic requirements. The highest numbers of M. alfredi observed in Hanifaru Bay corresponded to when they were engaged in feeding behaviour. The community composition of zooplankton was different when M. alfredi was feeding (dominated by copepods and crustaceans) compared to when present but not feeding (more gelatinous species present than in feeding samples). The dominant zooplankton species recorded was Undinula vulgaris. This is a large-bodied calanoid copepod species that blooms in oceanic waters, suggesting offshore influences at the site. Here, we have characterised aspects of the feeding environment for

Understanding how individual behavior shapes the structure and ecology of populations is key to species conservation and management. Like many elasmobranchs, manta rays are highly mobile and wide ranging species threatened by anthropogenic impacts. In shallow-water environments these pelagic rays often form groups, and perform several apparently socially-mediated behaviors. Group structures may result from active choices of individual rays to interact, or passive processes. Social behavior is known to affect spatial ecology in other elasmobranchs, but this is the first study providing quantitative evidence for structured social relationships in manta rays. To construct social networks, we collected data from more than 500 groups of reef manta rays over five years, in the Raja Ampat Regency of West Papua. We used generalized affiliation indices to isolate social preferences from non-social associations, the first study on elasmobranchs to use this method. Longer lasting social preferences were detected mostly between female rays. We detected assortment of social relations by phenotype and variation in social strategies, with the overall social network divided into two main communities. Overall network structure was characteristic of a dynamic fission-fusion society, with differentiated relationships linked to strong fidelity to cleaning station sites. Our results suggest that fine-scale conservation measures will be useful in protecting social groups of M. alfredi in their natural habitats, and that a more complete understanding of the social nature of manta rays will help predict population responses to anthropogenic pressures, such as increasing disturbance from dive-tourism.

The world is facing the global trend of Industry 4.0 in the manufacturing sectors. The concept of the Internet of Underwater Thing (IoUT) presents the trends in the underwater region. The Autonomous Underwater Vehicle (AUV) as a data collector and transmitter becomes the central component in the connected system of the IoUT. The efficiency of the platform is crucial to lengthening the range and duration of the mission. The biomimetic method of utilizing the caudal fin propulsion could enhance the efficiency of the small and low-speed AUV. From the defense perspective, there is a concept of Revolution in Military Affairs (RMA) that supports technological modernization for defense purposes. Technically, this study aims to combine the technical aspects of mechanical engineering and the defense concept of RMA in the technological advancement of AUV for the advanced and efficient defense strategy in the underwater region. The evaluations involved numerical simulation with Computational F...

International trade for luxury products, medicines, and tonics poses a threat to both terrestrial and marine wildlife. The demand for and consumption of gill plates (known as Peng Yu Sai, "Fish Gill of Mobulid Ray") from devil and manta rays (subfamily Mobulinae, collectively referred to as mobulids) poses a significant threat to these marine fishes because of their extremely low productivity. The demand for these gill plates has driven an international trade supplied by largely unmonitored and unregulated catches from target and incidental fisheries around the world. Scientific research, conservation campaigns, and legal protections for devil rays have lagged behind those for manta rays despite similar threats across all mobulids. To investigate the difference in attention given to devil rays and manta rays, we examined trends in the scientific literature and updated species distribution maps for all mobulids. Using available information on target and incidental fisheries...

Large tropical and sub-tropical marine animals must meet their energetic requirements in a largely oligotrophic environment. Many planktivorous elasmobranchs, whose thermal ecologies prevent foraging in nutrient-rich polar waters, aggregate seasonally at predictable locations throughout tropical oceans where they are observed feeding. Here we investigate the foraging and oceanographic environment around Lady Elliot Island, a known aggregation site for reef manta rays Manta alfredi in the southern Great Barrier Reef. The foraging behaviour of reef manta rays was analysed in relation to zooplankton populations and local oceanography, and compared to long-term sighting records of reef manta rays from the dive operator on the island. Reef manta rays fed at Lady Elliot Island when zooplankton biomass and abundance were significantly higher than other times. The critical prey density threshold that triggered feeding was 11.2 mg m-3 while zooplankton size had no significant effect on feedi...

ABSTRAKSejak 1990 Pangandaran telah berkembang menjadi salah satu tujuan wisata utama di Jawa Barat yang memfokuskan pengembangannya pada wisata bahari. Perkembangan itu menarik banyak wisatawan dan berdampak pada kondisi ekosistem laut. Terumbu karang secara perlahan dirusak oleh kegiatan wisatawan, limbah plastik dan polusi, sehingga kejernihan air terdegradasi. Program ini dilakukan untuk menganalisis tingkat kerusakan terumbu karang dan kesiapan masyarakat dalam membudidayakan terumbu karang, serta menyediakan pelatihan kepada masyarakat sehingga model transplantasi akan dihasilkan. Subjek dari pelatihan ini adalah komunitas nelayan di Kecamatan Pananjung. Pelatihan disampaikan dalam tahapan: 1) identifikasi kondisi terumbu karang di Perairan Cagar Alam; 2) analisis kesiapan dan kemampuan masyarakat dalam mengembangkan budidaya terumbu karang, dan 3) pelatihan dalam budidaya terumbu karang bagi masyarakat. Sasaran dari kegiatan ini adalah untuk meningkatkan kualitas lingkungan p...

Biomimetics aims to take inspiration from nature and develop new models and efficient systems for a sustainable future. Bioinspired underwater robotics help develop future submarines that will navigate through the water using flexible propulsor. This research has focused on the Manta Ray species as batoid has a unique advantage over other species. This study also aims to improve AUV (Autonomous Underwater Vehicle) efficiency through biomimetic design, the purpose of which is to observe and study the marine environment, be it for sea exploration or navigation. The design and prototyping process of bioinspired AUVs have been mentioned in this study, along with testing a propulsive mechanism for efficient swimming and turning capabilities. The Robot was designed taking structural considerations from the actual Manta-Ray locomotion and body design. The propulsion mechanism and control circuit were then implemented on the developed systems. The prototype of the Manta Ray was able to gene...

Research into the movement ecology of terrestrial and marine animals is growing globally, especially for threatened species. Understanding how far an animal can move and the extent of its range can inform conservation planning and management. On the east coast of Australia, reef manta rays Mobula alfredi are the subject of a photographic identification study, Project Manta. In June 2018, videos of reef manta rays from the SS Yongala (19.31°S, 147.62°E), were submitted to the Project Manta east coast sightings database. The videos were of two individuals previously identified from North Stradbroke Island (27.42°S, 153.55°E), about 1150 km to the south of the SS Yongala. This represents the greatest point-to-point distance travelled by individual M. afredi and extends the latitudinal range for this sub-population on the east coast. This study highlights that citizen science input can provide valuable data to address knowledge gaps in the distribution and population range of marine species. Knowledge of the 1000+ km range movement potential of individual M. alfredi, highlights the possibility that regional sub-populations may span jurisdictional zones of more countries than previously considered likely, complicating conservation management of this species.

Biomimetics aims to take inspiration from nature and develop new models and efficient systems for a sustainable future. Bioinspired underwater robotics help develop future submarines that will navigate through the water using flexible propulsor. This research has focused on the Manta Ray species as batoid has a unique advantage over other species. This study also aims to improve AUV (Autonomous Underwater Vehicle) efficiency through biomimetic design, the purpose of which is to observe and study the marine environment, be it for sea exploration or navigation. The design and prototyping process of bioinspired AUVs have been mentioned in this study, along with testing a propulsive mechanism for efficient swimming and turning capabilities. The Robot was designed taking structural considerations from the actual Manta-Ray locomotion and body design. The propulsion mechanism and control circuit were then implemented on the developed systems. The prototype of the Manta Ray was able to generate a realistic swimming pattern and was tested in an acrylic tank. The experimental results obtained in the tank basin are very close to the results we observe in the real-world scenario in terms of the vehicle's forward and turning motion.

Research into the movement ecology of terrestrial and marine animals is growing globally, especially for threatened species. Understanding how far an animal can move and the extent of its range can inform conservation planning and management. On the east coast of Australia, reef manta rays Mobula alfredi are the subject of a photographic identification study, Project Manta. In June 2018, videos of reef manta rays from the SS Yongala (19.31°S, 147.62°E), were submitted to the Project Manta east coast sightings database. The videos were of two individuals previously identified from North Stradbroke Island (27.42°S, 153.55°E), about 1150 km to the south of the SS Yongala. This represents the greatest point-to-point distance travelled by individual M. afredi and extends the latitudinal range for this sub-population on the east coast. This study highlights that citizen science input can provide valuable data to address knowledge gaps in the distribution and population range of marine species. Knowledge of the 1000+ km range movement potential of individual M. alfredi, highlights the possibility that regional sub-populations may span jurisdictional zones of more countries than previously considered likely, complicating conservation management of this species.

The Alfred manta, Manta alfredi, is economically important in the Maldives due to the large number of tourists attracted to SCUBA dive and snorkel with them. It is important to understand the size of populations around main diving points and throughout the Maldives so that manta based tourism activities can be developed more successfully and the impact of tourism can be monitored. Using natural markings to identify individual manta rays, Petersen and Jolly-Seber probabilistic estimators were used to assess population size for main dive sites and the central atolls of North Male, Ari and Baa. Between 2000 and 2009, 1835 individual mantas were identified from 3373 sightings. There was a significant gender bias with a male: female ratio of 1:1.8. Only 24.7% of manta rays were re-sighted between 1 and 34 times with a maximum gap of 7 years and 11 months between sightings. Estimates for populations around main dive sites were 181-562. The estimated population of M. alfredi for North Male atoll is 537 (SE±53.2). Estimated atoll populations were extrapolated to obtain an estimate of Manta alfredi population for the entire Maldives of 9,677 individuals.

International trade for luxury products, medicines, and tonics poses a threat to both terrestrial and marine wildlife. The demand for and consumption of gill plates (known as Peng Yu Sai, "Fish Gill of Mobulid Ray") from devil and manta rays (subfamily Mobulinae, collectively referred to as mobulids) poses a significant threat to these marine fishes because of their extremely low productivity. The demand for these gill plates has driven an international trade supplied by largely unmonitored and unregulated catches from target and incidental fisheries around the world. Scientific research, conservation campaigns, and legal protections for devil rays have lagged behind those for manta rays despite similar threats across all mobulids. To investigate the difference in attention given to devil rays and manta rays, we examined trends in the scientific literature and updated species distribution maps for all mobulids. Using available information on target and incidental fisheries...

In this paper, inspired by the external morphology of a manta ray (Mobula alfredi), four chimerical wing planforms are designed to assess its gliding performance. The planforms possess an arbitrary combination of extra hydrodynamic features including tubercles at the leading edge (L.E.) and trailing edge (T.E.) inspired by humpback whale's flippers and flukes, respectively, as well as longitudinal ridges inspired by whale shark's eidonomy. In addition, another planform is designed to investigate the possible effects of manta ray's injuries (geometric deficiency) generated by predator's attacks or boat strikes on its locomotion (gliding) performance. In this regard, turbulent flow physics involved in the problem is numerically simulated at different angles of attack (AoA). High Reynolds number, 10^6, corresponding to the swimming of a juvenile manta ray at an average speed equals 1 m/s. The results show that the manta ray-inspired planform with L.E. undulations exhibits a superior performance at high AoAs than its other counterpart variants. In addition, the results demonstrate that injuries on the manta ray's body can noticeably modify hydrodynamics and, as a result corresponding hydrodynamical forces and moments acting on the swimming animal in the gliding phase.

Se elaboró un listado taxonómico de las rayas (Piscis: Batoidea), en la Plataforma Continental de la región Soconusco, Chiapas, México. Esta información se obtuvo de colectas realizadas en enero desde 2002 hasta noviembre de 2010. De 48 ejemplares analizados, se encontró un total de cuatro órdenes, 10 familias, 10 géneros y 11 especies. Los resultados demuestran que el orden mejor representado fue Myliobatiformes. Las familias mejor representadas fueron Myliobatidae y Narcinidae con dos géneros respectivamente y el género mejor representado fue Narcine con dos especies. La presente información sirve como antecedente para investigaciones o estudios que incidan en la región.

Manta ray watching tourism worldwide has been reported to bring a
significant economic impact that contributes to the effective
management of sustainable wildlife tourism. This study was conducted
to analyse the role of small-scale tourism businesses in Marine Protected
Areas (MPAs) of Nusa Penida, Komodo, and Raja Ampat, both in
Indonesia, that offers manta ray tours and determines their significant
contribution to the park management. We conducted surveys with 101
respondents from manta ray tourism services and phone interviews with
three park managers. The results of this study indicate that more than
90% of respondents engage in conservation activities. The small-scale
businesses include boat rentals, gear rentals, dive shops, tour operators,
homestays and souvenir shops that promote manta ray conservation
through their products and services; educating tourists and staff,
collecting plastics when diving and snorkelling, regular beach cleanups, waste management, recycling programs, manta ray monitoring and
photo ID activities. Furthermore, the Marine Protected Area (MPA)
management confirmed by establishing a partnership with the smallscale manta ray’s tourism businesses to ensure the authentic manta ray
experience for tourists and achieving sustainable businesses for the
locals. In summary, there are three significant roles of small-scale manta
ray tourism business including species protection, sustainable tourism
compliance, and effective MPA management that still needs to be
strengthened to provide maximum benefits to conservation and tourism.

This research was conducted in Karang Makassar, Komodo National Park, East Nusa Tenggara, on 26th September to 18th November 2012. This research aimed to determine the temporal distribution and environmental influence against the sightings of manta rays in Karang Makassar waters, Komodo Komodo National Park, East Nusa Tenggara. Data capture used observation method, using Photo ID to recognize specific sign of an individual from photographic images. Parameters observed were the phases of the moon, tides, and chlorophyll-a concentration. The results showed the highest appearance in the West monsoon and the lowest in the East monsoon. Manta ray appearance was higher during the full moon and when the tide is rising, at optimum temperature between 27-29o C, with depth between 0-22 meters. From this study we determined that Chlorophyll-a concentration have a strong influence on manta rays sightings.