DEWA GEDE RAKA WIADNYA
Department of Fisheries, Faculty of Fisheries and Marine Science, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia

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presence of whale sharks based on oceanographic variations in Cenderawasih Bay National Park, Papua, Indonesia: The presence of whale sharks in Cenderawasih Bay National Park, Papua. JAFRY FERDINAN Manuhutu; DEWA GEDE RAKA WIADNYA; ABU BAKAR SAMBAH; ENDANG YULI HERAWATI
Biodiversitas Journal of Biological Diversity Vol. 22 No. 11 (2021)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d221129

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Abstract. Manuhutu JF, Wiadnya DGR, Sambah AB, Herawati EY. 2021. The presence of whale sharks based on oceanographic variations in Cenderawasih Bay National Park, Papua, Indonesia. Biodiversitas 22: 4948-4955. Oceanographic factors have an important role in the study of estimating the distribution of fish resource habitats. Sea Surface Temperature (SST), Sea Surface Chlorophyll (SSC), Current Speed, Sea Surface Height (SSH), and bathymetry are important parameters that have been used in estimating the habitat of certain species. Through analyzing these environmental factors, research on the appearance and distribution of whale shark habitats in the Cenderawasih Bay National Park in Papua, Indonesia, utilized field observation data and satellite imagery. This study applied data on the presence of whale sharks and oceanographic parameter data from satellite recordings during 2019 – 2020. Analysis of the relationship and habitat modeling between the monthly presence of whale sharks and environmental parameters was carried out through the Generalized Additive Model (GAM) statistical approach and spatial analysis through the Geographic Information System approach. In the GAM analysis, data on the presence of whale sharks was used as a response variable. In contrast, the predictor variables consisted of SST, SSC, current speed, SSH, and bathymetric data. The results showed that the highest frequency of whale shark presence occurred in the transitional monsoon, with an average presence of 31.77 ± 4.00 %. The study also showed that all predictors showed a highly significant relationship (P < 0.001) to the number of whale sharks present. SST values range from 30.3 – 31.3 °C, SSC of 0.39 – 0.86 mg/L, the current speed of 0.46 – 0.65 m/s, SSH showed 0.63 to 1.00 cm, and bathymetry between 40 – 50 m . In the GAM model, the SST and SSC parameters were the two most important parameters that affect the presence of whale sharks, followed by SSHD, depth (bathymetry), and current parameters.
Mitochondrial phylogeny and genetic diversity of Hampala barb (Hampala macrolepidota) from the Brantas River, Indonesia ELOK AMALIA; IFA SUFAICHUSAN; MUHAMMAD DAILAMI; ABD RAHEM FAQIH; MAHENO SRI WIDODO; DEWA GEDE RAKA WIADNYA; WAHYU ENDRA KUSUMA
Biodiversitas Journal of Biological Diversity Vol. 26 No. 11 (2025)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d261128

Abstract

Abstract. Amalia E, Sufaichusan I, Dailami M, Faqih AR, Widodo MS, Wiadnya DGR, Kusuma WE. 2025. Mitochondrial phylogeny and genetic diversity of Hampala barb (Hampala macrolepidota) from the Brantas River, Indonesia. Biodiversitas 26: 5694-5702. Hampala barb (Hampala macrolepidota), a native freshwater fish species in the Brantas River, East Java, is currently under severe threat due to intense fishing and environmental perturbations. The urgency of this situation necessitates the immediate implementation of effective genetic management and conservation programs, which rely on basic scientific information such as genetic characterization. This study aimed to assess the phylogenetic relationships, genetic diversity, population structure, and demographic history of H. macrolepidota using a 1,095 bp sequence of the mitochondrial DNA cytochrome b from 23 individuals collected across four sampling locations. Phylogenetic analysis showed that H. macrolepidota from the Brantas River clustered together and formed a single group with very shallow genetic divergence. Population structure analyses (both ?st and AMOVA) showed high gene flow and an absence of significant genetic clustering, suggesting the sampled area constitutes a single, interconnected population unit. The combination of high haplotype diversity (hd: 0.714-1.000) but low nucleotide diversity (?: 0.00156-0.00728), along with the negative Tajima’s D and Fu’s Fs values, suggested that the species has likely experienced a bottleneck effect followed by a rapid expansion in the past. This decline of genetic diversity points to a reduced long-term adaptive potential, causing the species to be highly vulnerable to future environmental changes, despite its current abundance. The results highlight the urgent need for effective genetic management and conservation programs for the species to focus on maintaining genetic connectivity and minimizing anthropogenic pressures to preserve the genetic integrity and long-term viability of the population. Future studies incorporating nuclear or genome-wide markers would provide finer resolution of population structure and complement the mitochondrial data presented here.