Monitoreo de fauna pelágica de los Montes submarinos del Pacífico colombiano usando BRUVS

In December 2021, we conducted the first expedition to the seamounts of the Malpelo and Yuruparí ridges. Eight seamounts were explored using Baited Remote Underwater Video Systems (BRUVS). A total of 48 BRUVS were deployed, registering five pelagic species (Sphyrna lewini, Mobula birostris, Pteroplatytrygon violacea, Kajikia audax and Istiophorus platypterus) where Pteroplatytrygon violacea constituted a new record for the region. Pelagic species were recorded in all seamounts, although sharks were exclusively associated with the seamounts to the west of the ridges, especially in the area known as Bajo Navegador, the shallowest seamount in the region. This work is a first step to guide the following explorations of these ecosystems.En diciembre de 2021 se desarrolló la primera expedición a los montes submarinos de las dorsales de Malpelo y de Yuruparí. En total se exploraron ocho montes submarinos por medio de BRUVS (Baited Remote Underwater Video Systems). Se desplegaron 48 BRUVS, registrando cinco especies pelágicas (Sphyrna lewini, Mobula birostris, Pteroplatytrygon violácea, Kajikia audax y Istiophorus platypterus), donde Pteroplatytrygon violácea constituyó un nuevo registro para la región. En todas las zonas se registraron especies pelágicas, aunque los tiburones se asociaron exclusivamente a los montes al oeste de las dorsales, en especial al monte conocido como Bajo Navegador, el más somero de la región. Este trabajo es un primer paso para orientar las siguientes exploraciones de estos ecosistemas

Moray eels are more common on coral reefs subject to higher human pressure in the greater Caribbean

Proximity and size of the nearest market (‘market gravity’) have been shown to have strong negative effects on coral reef fish communities that can be mitigated by the establishment of closed areas. However, moray eels are functionally unique predators that are generally not subject to targeted fishing and should therefore not directly be affected by these factors. We used baited remote underwater video systems to investigate associations between morays and anthropogenic, habitat, and ecological factors in the Caribbean region. Market gravity had a positive effect on morays, while the opposite pattern was observed in a predator group subject to exploitation (sharks). Environmental DNA analyses corroborated the positive effect of market gravity on morays. We hypothesize that the observed pattern could be the indirect result of the depletion of moray competitors and predators near humans. Environmental science; ecology; biological sciences; zoology; animals; etholog

Identification of two evolutionary significant units based on mitochondrial DNA and microsatellite evidence in the pelagic thresher shark (alopias pelagicus) in the Pacific Ocean

Magíster en Ciencias BiológicasMaestrí

Data from: Genetic diversity and population structure of the Pelagic Thresher Shark (Alopias pelagicus) in the Pacific Ocean: evidence for two evolutionarily significant units

There has been an increasing concern about shark overexploitation in the last decade, especially for open ocean shark species, where there is a paucity of data about their life histories and population dynamics. Little is known regarding the population structure of the pelagic thresher shark, Alopias pelagicus. Though an earlier study using mtDNA control region data, showed evidence for differences between eastern and western Pacific populations, the study was hampered by low sample size and sparse geographic coverage, particularly a lack of samples from the central Pacific. Here, we present the population structure of Alopias pelagicus analyzing 351 samples from six different locations across the Pacific Ocean. Using data from mitochondrial DNA COI sequences and seven microsatellite loci we found evidence of strong population differentiation between western and eastern Pacific populations and evidence for reciprocally monophyly for organelle haplotypes and significant divergence of allele frequencies at nuclear loci, suggesting the existence of two Evolutionarily Significant Units (ESU) in the Pacific Ocean. Interestingly, the population in Hawaii appears to be composed of both ESUs in what seems to be clear sympatry with reproductive isolation. These results may indicate the existence of a new cryptic species in the Pacific Ocean. The presence of these distinct ESUs highlights the need for revised management plans for this highly exploited shark throughout its range

Data from: Genetic diversity and population structure of the Pelagic Thresher Shark (Alopias pelagicus) in the Pacific Ocean: evidence for two evolutionarily significant units

There has been an increasing concern about shark overexploitation in the last decade, especially for open ocean shark species, where there is a paucity of data about their life histories and population dynamics. Little is known regarding the population structure of the pelagic thresher shark, Alopias pelagicus. Though an earlier study using mtDNA control region data, showed evidence for differences between eastern and western Pacific populations, the study was hampered by low sample size and sparse geographic coverage, particularly a lack of samples from the central Pacific. Here, we present the population structure of Alopias pelagicus analyzing 351 samples from six different locations across the Pacific Ocean. Using data from mitochondrial DNA COI sequences and seven microsatellite loci we found evidence of strong population differentiation between western and eastern Pacific populations and evidence for reciprocally monophyly for organelle haplotypes and significant divergence of allele frequencies at nuclear loci, suggesting the existence of two Evolutionarily Significant Units (ESU) in the Pacific Ocean. Interestingly, the population in Hawaii appears to be composed of both ESUs in what seems to be clear sympatry with reproductive isolation. These results may indicate the existence of a new cryptic species in the Pacific Ocean. The presence of these distinct ESUs highlights the need for revised management plans for this highly exploited shark throughout its range

Occurrence of juvenile bull sharks (Carcharhinus leucas) in the Navua River in Fiji

Effective species conservation requires the protection of all stages of its life-cycle. The Shark Reef Marine Reserve (SRMR) in Fiji is a marine protected area where large numbers of adult bull sharks (Carcharhinus leucas) congregate due to food provisioning. At the end of a calendar year bull sharks leave the area for reproductive activity, but parturition sites are still unknown. Between February 2014 and January 2015, we interviewed local fishermen and conducted a fishing survey, so as to assess presence and abundance of bull sharks in the Navua River near the SRMR. In total 84% of fishermen reported either seeing or catching sharks up to 8 km upriver from the river mouth. They described them as small sharks having a rounded snout and being grey–brown in colour with a white belly, morphological characteristics that match juvenile bull sharks. During the fishing survey, a total of nine juvenile bull sharks were captured, including two that were recaptured after 108 and 92 days at liberty. Our findings confirmed the presence of bull sharks in the Navua River and provide a preliminary characterisation of a potential shark parturition or nursery area from a data-poor region

Population differentiation based on Jost's D and Exact test values between pairwise populations with seven microsatellite loci.

<p>Significant scores after Bonferroni correction are in bold. Below diagonal Jost's D values with 95% confidence intervals and above diagonal exact test significance. Degrees of significance: p<0.0018 (+). p<0.000001 (++). Mitochondrial DNA clade and numbers of samples per location are shown in parentheses.</p><p>Population differentiation based on Jost's D and Exact test values between pairwise populations with seven microsatellite loci.</p

Pairwise Fst (below diagonal) and Φst (above diagonal) values for the COI gene when only Clade B haplotypes of <i>Alopias pelagicus</i> are analyzed.

<p>Probability values based on 10,000 permutations are shown in italic. Significant different values (p<0.05) in bold. Haplotype (h) and nucleotide (π) % ± standard deviation (SD) diversity values are shown in the diagonal of each population unit. Numbers of samples per location are shown in parentheses.</p><p>Pairwise Fst (below diagonal) and Φst (above diagonal) values for the COI gene when only Clade B haplotypes of <i>Alopias pelagicus</i> are analyzed.</p

Map indicating sampling locations in the Pacific Ocean.

<p>TW = Taiwan, HH = Hawaii, BA = Baja, SC = Southern California, CL = Clipperton Island, CR = Costa Rica, COL = Colombia, ECU = Ecuador. Sample numbers for each location are shown in parentheses.</p

Pairwise Fst (below diagonal) and Φst (above diagonal) values for the COI gene from the Pacific Ocean populations of <i>Alopias pelagicus</i>.

<p>Probability values based on 10,000 permutations are shown in italic. Significant scores after Bonferroni correction are in bold. Haplotype (h) and nucleotide (π) % ± standard deviation (SD) diversity values are shown in the diagonal of each population unit. Numbers of samples per location are shown in parentheses.</p><p>Pairwise Fst (below diagonal) and Φst (above diagonal) values for the COI gene from the Pacific Ocean populations of <i>Alopias pelagicus</i>.</p