Microplastics in Indonesian Megafauna Habitats ray egested material confirmed plastic ingestion, the consequences of which might include exposure to toxic plastic additives and adhered persistent organic pollutants. Communicating this information to communities who stand to benefit from healthy megafauna populations might help local governments as they work toward reducing plastics in the marine environment.
Background The whale shark (Rhincodon typus) is a prominent species in Cenderawasih Bay. Its recent association with moored lift-net fisheries there has led to an increase in tourism that facilitates encounters for human snorkelers and SCUBA divers with the sharks. This association has also supported opportunities for research to discover various elements of their biology, ecology, movements and genetics. An understanding of the genetic composition of the sharks in Cenderawasih Bay and their relationships with whale sharks elsewhere in the Indian Ocean and Western Pacific Ocean is important for their conservation and to help design marine protected areas. Approach Skin samples from whale sharks in Cenderawasih Bay were collected with modified hog ear notch pliers and small biopsy tips. The samples were preserved in 96% ethanol and stored at 4°C in the laboratory until DNA extraction. The DNA template was amplified for the cytochrome oxidase I (COI) gene. The nucleotide composition and genetic diversity (polymorphisms, haplotypes, and nucleotides) were analyzed. The results from whale sharks in Cenderawasih Bay were compared with those available in Genbank for nearby areas of the Indian and Western Pacific oceans with the neighbor-joining method. Evolutionary distances and haplotype networks were calculated. Results Seven haplotypes were detected among the 31 whale sharks sampled in Cenderawasih Bay, for a haplotype diversity (Hd) of 0.1871 (variance = 0.00859, s.d. = 0.093). The nucleotide diversity (Φ) was 0.00244 (±0.0013) and the values for theta were 0.75094 per shark and 0.00722 per site. The neighbour-joining tree for individual whale sharks from Cenderawasih Bay and other regions appeared to be closely related to each other. They also appeared to be closely related to whale sharks sampled elsewhere in the Indian and Western Pacific oceans (Chi-square, Chi2: 3.620, df: 5, p: 0.605). Haplotype one has highest frequency (37 individuals), one haplotype has two individuals, and six other haplotypes each have one individual. The three last haplotypes have just one individual, respectively. The whale sharks that we sampled in Cenderawasih Bay had low genetic diversity (haplotype, nucleotide and polymorphic). Conclusion 31 whale sharks in Cenderawasih Bay were very closely related, and these sharks were closely related to whale sharks elsewhere in the Indian and Western Pacific oceans. The extent of movements among reproductive sharks in this large region is unknown as is the frequency and magnitude of mating among sharks from these different areas. Further research is needed to monitor the long-term movements of sharks within and among regions, particularly reproductively mature males and females, to help design conservation plans for whale sharks and the habitats that they might depend on for feeding andreproducing.
The world’s largest extant fish, the whale shark Rhincodon typus, is one of the most-studied species of sharks globally. The discovery of predictable aggregation sites where these animals gather seasonally or are sighted year-round – most of which are coastal and juvenile-dominated – has allowed for a rapid expansion of research on this species. The most common method for studying whale sharks at these sites is photographic identification (photo-ID). This technique allows for long-term individual-based data to be collected which can, in turn, be used to evaluate population structure, build population models, identify long-distance movements, and assess philopatry and other population dynamics. Lagged identification rate (LIR) models have fewer underlying assumptions than more traditional capture mark recapture approaches, making them more broadly applicable to marine taxa, especially far-ranging megafauna species like whale sharks. However, the increased flexibility comes at a cost. Parameter estimations based on LIR can be difficult to interpret and may not be comparable between areas with different sampling regimes. Using a unique data-set from the Philippines with ~8 years of nearly continuous survey effort, we were able to derive a metric for converting LIR residency estimates into more intuitive days-per-year units. We applied this metric to 25 different sites allowing for the first quantitatively-meaningful comparison of sightings-derived residence among the world’s whale shark aggregations. We validated these results against the only three published acoustic residence metrics (falling within the ranges established by these earlier works in all cases). The results were then used to understand residency behaviours exhibited by the sharks at each site. The adjusted residency metric is an improvement to LIR-based population modelling, already one of the most widely used tools for describing whale shark aggregations. The standardised methods presented here can serve as a valuable tool for assessing residency patterns of whale sharks, which is crucial for tailored conservation action, and can cautiously be tested in other taxa.
Background The composition of sex and size of a population is important for management and conservation of marine organisms, including high mobility and global species such as the whale shark, Rhincodon typus. The presence of fish in lift nets in some Indonesian waters attracts feeding whale sharks. The objective of our study was to compare the sex, size and behaviour of whale sharks associated with lift nets in Cenderawasih Bay, Papua and Talisayan, East Kalimantan. Approach Data sampling was conducted for 52 days during April'June 2013 in Teluk Cenderawasih National Park, Papua and 60 days during August–October 2015 in Talisayan, East Kalimantan. Daily monitoring was carried out at lift nets located within the study area. Individual identification was conducted with photographic identification, sex determination was done through visual observation of the presence of reproductive organs, and size measurement was done by comparing the shark length with the observer–s height. Analysis of the fish catch was obtained by interviewing fishermen, and observation from the lift net was conducted to support the data. Results A total of 134 observations and 81 observations were recorded in Cenderawasih Bay (57 lift nets) and in Talisayan (43 lift nets), respectively. A total of 37 different whale shark individuals were identified in Cenderawasih Bay, and 30 different individuals were identified in Talisayan. More than 50% of the whale sharks in Cenderawasih Bay, and 80% in Talisayan, had scars on their bodies. In Cenderawasih Bay, scars were spread across the body: 20% of the scars were found on the fins, 20% on the main body including the gills, and 15.6% near the mouth area. In Talisayan, 70.6 % of the scars were found on the fins, 2.9% in the main body including the gills, and 17.6% near the mouth area. The scars result primarily from friction with fishing nets. The whale shark aggregations in Cenderawasih Bay and Talisayan were dominated by juvenile males. From a total of 37 individuals, only one female was found in Cenderawasih Bay, and from a total of 30 individuals, only two females were found in Talisayan. The dominant size of whale sharks in Cenderawasih Bay was in the range from 3–3.9 m total length, with the largest animals in the range of 6–6.9 m. In Talisayan, the dominant size range was 4–4.9 m total length, with the largest animals in the range of 6–6.9 m. The high abundance of smaller fishes that are caught in Cenderawasih Bay and Talisayan by lift nets could attract whale sharks to the area. The largest number of whale sharks seen in Cenderawasih Bay was 14 individuals on May 14th, 2013. The fishery catch in this area fluctuates, with the highest catch being 365 kg on May 9th, 2013. Whale shark activity in Talisayan was lower than Cenderawasih Bay, even with a greater lift net catch. The largest number of whale sharks seen in Talisayan was 8 individuals on August 25th, 2015. The lift net catch in this area also fluctuates, with the highest catch being 5,325 kg on August 25th, 2015. Conclusion The appearance and activity of whale sharks in Cenderawasih Bay and Talisayan have similar characteristics. These aggregations are dominated by males with a size range of 3–6 m, which are still categorized as juveniles. They were often present at the surface, performing feeding behaviours that correlate with lift net activity.
Protection and sustainable data collection are very important in order to protect the coral reef ecosystem. This research was conducted to monitor and determine the condition of coral reefs in the eastern part of Gili Gede Island, which is administratively located in Sekotong Sub-District, West Lombok Regency, NTB. The method used is Line Intercept Transect (LIT). Furthermore, the starting point of the transect stretch is recorded using GPS coordinates and the depth gauge is used to estimate the depth of the water. The results showed that the status of coral reefs tended to be badly damaged with the mean value of all stations (21.92%). Fishery activities and pressure from the land are thought to be several factors that tend to affect the poor coastal ecosystem
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.