Evidence of extensive genetic connectivity and recent demographic expansion of the queen mackerel Scomberomorus plurilineatus in Tanzanian coastal waters

Rumisha, Cyrus; Bugota, Valeli J.; Mtonga, Cretus Joseph

doi:10.1007/s12526-022-01315-y

Cited by 8 publications

(6 citation statements)

References 36 publications

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“…Given the strong influence of oceanic currents in the SWIO, especially the South Equatorial Current (SEC) that bifurcates near southern Tanzania into the northward East African Coastal Current (EACC) and the southward Mozambique Current (MC) (Schott & McCreary, 2001), there is potential for these currents to transport larvae extensively within the region, thereby contributing to the observed genetic homogeneity among Barred mudskipper populations. The influence of the EACC, a northward branch of the SEC flowing along the Tanzanian and Kenyan coastline, aligns with a broader trend of high connectivity observed not only in the studied mudskipper populations but also in other marine fauna from East Africa (Fratini et al., 2010; Rumisha et al., 2023; Simwanza & Rumisha, 2023). Similarly, the MC, a southern branch of the SEC flowing from southern Tanzania downward into the Mozambique Channel, could also facilitate the transport of pelagic larvae over extensive distances within the channel (Singh et al., 2019).…”

Section: Discussionsupporting

confidence: 81%

Transcending borders: Remarkable genetic homogeneity among Barred mudskipper (Periophthalmus argentilineatus) populations in the southwestern Indian Ocean

Rumisha

2024

Afr J Ecol

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In the past 24 years, the Southwestern Indian Ocean (SWIO) region has lost about 4% of its mangroves due to unsustainable extraction, land clearance for agriculture and climate change impacts. Since this loss risks fragmenting mangrove fauna, this study analysed 179 D‐loop sequences (329 base pairs) of Barred mudskipper (Periophthalmus argentilineatus) sampled from estuarine mangroves in the SWIO to test two hypotheses: (1) whether Barred mudskipper populations in the region display genetic connectivity along the fragmented mangroves and (2) whether these populations have experienced demographic declines in recent history. The populations showed low and insignificant indices of genetic differentiation (FST = −0.00068, p > 0.05; ΦST = 0.005, p > 0.05), and haplotypes from different localities did not cluster according to their geographical origins. Similarly, Bayesian phylogenetic analysis grouped all SWIO haplotypes into one cluster, suggesting the hypothesis of genetic interconnectedness could not be rejected. Furthermore, the populations showed high haplotype diversity (0.96 ± 0.007) combined with low nucleotide diversity (1.09 ± 0.61%). They also showed significant negative Tajima's D values (−1.71, p < 0.02) and a unimodal mismatch distribution, indicating the hypothesis of demographic expansion post a historical bottleneck could not be rejected. Nevertheless, the Bayesian skyline plot indicated an increase in population size post‐bottleneck, suggesting an ongoing recovery. These findings indicate that, despite varying management approaches in the SWIO, Barred mudskipper populations exhibit genetic exchange that transcends geographical and administrative borders. This implies that their populations should be considered a single stock within the region. These findings underscore the need for coordinated management approaches among the SWIO countries. This is crucial because inconsistencies in conservation measures across borders could disrupt the population's interconnectedness, potentially impacting their genetic integrity and long‐term survival.

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Section: Discussionsupporting

confidence: 81%

Transcending borders: Remarkable genetic homogeneity among Barred mudskipper (Periophthalmus argentilineatus) populations in the southwestern Indian Ocean

Rumisha

2024

Afr J Ecol

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“…Edited COI sequences were then translated into amino acid sequences using the vertebrate genetic code in MEGA ver. 11 to check for the presence of sequencing artifacts and nuclear pseudogenes (Mgeleka et al., 2023; Rumisha et al., 2023). After cleaning, 127 COI sequences remained and were submitted to the National Centre for Biotechnology Information (NCBI) under accession numbers OR138542–OR138668 and OR759455–OR759484.…”

Section: Methodsmentioning

confidence: 99%

“…However, hydropower dams in the RRB, like the Kidatu dam on the Ruaha River (Dye & Hartmann, 2017; Tesha et al., 2003), are barriers to fish migration that hinder dispersal of larvae and adults between the Ramsar site and areas outside its boundaries (Arantes et al., 2019). When combined with habitat degradation and unsustainable fishing practices, these factors can reduce gene flow and increase genetic differentiation among populations (Martinez et al., 2018; Rumisha et al., 2023). Therefore, we quantified the extent of genetic connectivity between populations of B. orientalis in the Kilombero Valley Foodplain Ramsar site (KVFPRS) and those in other areas within the RRB.…”

Section: Introductionmentioning

confidence: 99%

Restricted genetic connectivity and conservation prospects of Bagrid catfish, Bagrus orientalis, populations in the Rufiji River basin, Tanzania

Saiperaki,

Materu,

Mkenda

et al. 2024

Fisheries Management Eco

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The Bagrid catfish, Bagrus orientalis, historically sustained communities in the Rufiji River basin (RRB), Tanzania, but has rapidly declined due to high consumer demand and unsustainable fishing. Consequently, a Ramsar site was designated within the RRB, although its potential to revitalize overexploited populations beyond its boundaries is uncertain because of limited information on genetic connectivity. To address this uncertainty, 158 partial cytochrome oxidase subunit I sequences of B. orientalis were analyzed to quantify genetic connectivity in the RRB. We observed significant genetic differentiation, indicating limited connectivity among populations. Populations in the Ramsar site were genetically connected to those in the Kilombero Valley Floodplain (KVFP), but were distinct from those in Ruaha and Rufiji, which clustered separately. Our findings suggested the Ramsar site could revitalize overexploited KVFP populations, and emphasized the need for sustained efforts against its encroachment. However, limited genetic connectivity with Ruaha and Rufiji implied that conservation measures in the site might have restricted effect in these areas. Conservation efforts should extend beyond the Ramsar site, by promoting sustainable fishing and enhancing habitat connectivity in Ruaha and Rufiji.

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“…11. This step aimed to identify potential sequencing artefacts and nuclear pseudogenes (Morandus & Rumisha, 2024; Rumisha, Bugota, & Mtonga, 2023). The sequences were then reduced to haplotypes using the online service FaBox DNA Collapser (https://users-birc.au.dk/~palle/php/fabox/dnacollapser.php, consulted on 25/02/2024).…”

Section: Methodsmentioning

confidence: 99%

“…This analysis aimed to evaluate the relationships between the sampled sequences. One Queen mackerel ( Scomberomorus plurilineatus ) COI sequence with accession number OK035446 (Rumisha, Bugota, & Mtonga, 2023) was retrieved from the GenBank nucleotide database and included in the phylogenetic analysis as an outgroup.…”

Section: Methodsmentioning

confidence: 99%

Threatening the endangered: Uncovering endangered elasmobranchs and factors perpetuating the Tanzanian shark‐fin trade

Rumisha,

Barongo,

Saiperaki

et al. 2024

Afr J Ecol

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Despite global conservation efforts, elasmobranchs still face increased fishing pressure due to high demand for their products. Although certain species have been afforded international and local protection, the high value of their products in international markets incentivises the trade of protected species covertly within marketed fish products. To address the problem, we amplified fragments of the cytochrome oxidase subunit I gene (approximately 595 base pairs) from 164 elasmobranch fins collected from fish markets in Tanzania to test whether protected species and those of conservation concern are among these specimens. Similarly, we conducted 130 in‐depth key informant interviews with stakeholders involved in the elasmobranch‐fin trade to gather diverse perspectives on the factors perpetuating the trade. Our findings revealed fifteen elasmobranch species, with requiem sharks (Carcharhinidae) and wedgefishes (Rhinidae) accounting for 44.1% and 33.8% of the fins, respectively. Alarmingly, over 70% of the traded fins originated from threatened elasmobranchs, with 36.8% sourced from critically endangered species. Unexpectedly, almost 9% of the traded fins were sourced from two nationally protected species, Carcharhinus longimanus and Alopias pelagicus, highlighting the existence of regulatory gaps that require immediate attention. Similarly, 91.2% of traded fins were sourced from CITES‐listed species, emphasising the severity of the problem. The interviews highlighted technological challenges in tracking the trade, limited awareness of trade impacts on elasmobranch sustainability, scarce surveillance resources, inadequate training to identify routes and offenders and lack of public support as the main factors perpetuating the trade. Addressing these issues necessitates a total ban on elasmobranch‐fin trade, coupled with increased funding for enforcement agencies, providing specialised training for law enforcement personnel, launching public awareness campaigns and promoting community‐based monitoring and collaboration with international organisations. By doing so, Tanzania can effectively safeguard the sustainability of threatened elasmobranchs and advance global conservation efforts for these fishes.

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Evidence of extensive genetic connectivity and recent demographic expansion of the queen mackerel Scomberomorus plurilineatus in Tanzanian coastal waters

Cited by 8 publications

References 36 publications

Transcending borders: Remarkable genetic homogeneity among Barred mudskipper (Periophthalmus argentilineatus) populations in the southwestern Indian Ocean

Transcending borders: Remarkable genetic homogeneity among Barred mudskipper (Periophthalmus argentilineatus) populations in the southwestern Indian Ocean

Restricted genetic connectivity and conservation prospects of Bagrid catfish, Bagrus orientalis, populations in the Rufiji River basin, Tanzania

Threatening the endangered: Uncovering endangered elasmobranchs and factors perpetuating the Tanzanian shark‐fin trade

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