Caracterización de marcadores moleculares del tiburón ballena (Rhincodon typus) del Golfo de California

IMPRESO Y PD

Distribution of whale shark (Rhincodon typus) off northern Peru based on habitat suitability

In the south-eastern Pacific Ocean, few studies of whale sharks (Rhincodon typus) exist. In Peru, the northern coast has been identified as the area with the highest presence of whale sharks, yet their ecology in this area is poorly defined. This study predicts the spatial distribution of whale sharks off coastal northern Peru (03°00′S–04°30′S) during La Niña and El Niño seasonal conditions, utilizing maximum entropy modelling. Between 2009 and 2018 (except for 2011), 347 whale sharks were geo-referenced in northern Peru with greatest data recordings in the austral summer and spring during La Niña events. Depth was the most important predictive variable for spatial distribution of whale sharks, followed by chlorophyll-a. Sharks were predicted in shallower coastal waters in which chlorophyll-a values are higher. Habitat suitability was higher in the northern coastal part of the study area. Spring presents the most suitable environmental conditions for whale sharks, both during La Niña and El Niño conditions. The probability of whale shark presence in the north of Peru increases at higher chlorophyll-a and sea surface temperature values. Therefore, whale sharks appear to aggregate seasonally in northern Peru, potentially exploiting rich foraging grounds. In these areas of high suitability, whale sharks are susceptible to fisheries, bycatch, ship collisions, unmanaged tourism, and pollution; thus, management actions should focus in these areas. This study represents a first step to understand the distribution and habitat suitability of whale shark in Peruvian waters. Further studies should identify suitable habitat for whale sharks in offshore areas. Also, these should focus on the connectivity of these aggregations with other localities in the south-eastern Pacific in order to contribute to regional strategies for the conservation of this iconic species in this particular region

Population structure of the Pacific angel shark (Squatina californica) along the northwestern coast of Mexico based on the mitochondrial DNA control region

Population structure has direct consequences on species evolution, local adaptation, and the capacity of a metapopulation to adapt to climate change. In this study we assess the genetic structure and demographic history of the Pacific angel shark, Squatina californica, along the northwestern coast of Mexico using the mitochondrial control region. Results showed high levels of genetic diversity and reveal genetic differentiation between the samples from the Pacific coast of the Baja California Peninsula and those from the Gulf of California. These genetic differences are consistent with ontogenetic differences previously reported for S. californica off the northwestern coast of Mexico. Our findings can be explained by the low dispersal ability and habitat preference of the angel shark and by the complex geomorphology off the northwestern coast of Mexico. Contrasting historical demographic patterns were observed: population expansion in the gulf and population stability, with a declining trend, in the Pacific; however, more studies are required to corroborate demographic patterns in both populations. Our results point to 2 distinct management units of the Pacific angel shark in the study area, and this may have direct implications for the management and conservation of this species in Mexico.

Oceanic adults, coastal juveniles: tracking the habitat use of whale sharks off the Pacific coast of Mexico

Eight whale sharks tagged with pop-up satellite archival tags off the Gulf of California, Mexico, were tracked for periods of 14–134 days. Five of these sharks were adults, with four females visually assessed to be pregnant. At least for the periods they were tracked, juveniles remained in the Gulf of California while adults moved offshore into the eastern Pacific Ocean. We propose that parturition occurs in these offshore waters. Excluding two juveniles that remained in the shallow tagging area for the duration of tracking, all sharks spent 65 ± 20.7% (SD) of their time near the surface, even over deep water, often in association with frontal zones characterized by cool-water upwelling. While these six sharks all made dives into the meso- or bathypelagic zones, with two sharks reaching the maximum depth recordable by the tags (1285.8 m), time spent at these depths represented a small proportion of the overall tracks. Most deep dives (72.7%) took place during the day, particularly during the early morning and late afternoon. Pronounced habitat differences by ontogenetic stage suggest that adult whale sharks are less likely to frequent coastal waters after the onset of maturity

Microplastic occurrence in La Paz Bay (Mexico) and phthalate esters concentration in two resident filter-feeder species

Release of hazardous chemicals from floating plastic debris may cause toxicological effects on marine species. Phthalate esters (PAEs) are suggested to act as endocrine disruptors even at low concentrations. Large filter-feeding species, characterized by a long life span and a continue feeding activity, are potentially chronically exposed to these contaminants both leaching from ingested plastics and from their degradation and through the food chain. In this study, we evaluate the abundance and the polymer characterizations by FTIR spectroscopy of microplastics collected through surface-trawling plankton nets in the Bay of La Paz, Mexico. The increasing human pressure in this area is giving rise to chemical pollution from urban wastewaters, agriculture and maritime activities. Presence of six PAEs as plastic tracers has been assessed in neustonic samples and in skin biopsy samples of fin whales (Balaenoptera physalus) and whale sharks (Rhyncodon typus) by GC-qMS. Sixty six per cent of the net tows contained plastics with a maximum of 0.22 items/m3. Neustonic samples showed different fingerprint of PAEs, indicating heterogeneous levels and spatial patterns in the investigated area. Diethylhexyl phthalate presented the highest values in all samples analyzed, with a concentrations ranged fro

Oceanic adults, coastal juveniles: tracking the habitat use of whale sharks off the Pacific coast of Mexico

Eight whale sharks tagged with pop-up satellite archival tags off the Gulf of California, Mexico, were tracked for periods of 14–134 days. Five of these sharks were adults, with four females visually assessed to be pregnant. At least for the periods they were tracked, juveniles remained in the Gulf of California while adults moved offshore into the eastern Pacific Ocean. We propose that parturition occurs in these offshore waters. Excluding two juveniles that remained in the shallow tagging area for the duration of tracking, all sharks spent 65 ± 20.7% (SD) of their time near the surface, even over deep water, often in association with frontal zones characterized by cool-water upwelling. While these six sharks all made dives into the meso- or bathypelagic zones, with two sharks reaching the maximum depth recordable by the tags (1285.8 m), time spent at these depths represented a small proportion of the overall tracks. Most deep dives (72.7%) took place during the day, particularly during the early morning and late afternoon. Pronounced habitat differences by ontogenetic stage suggest that adult whale sharks are less likely to frequent coastal waters after the onset of maturity

Are whale sharks exposed to persistent organic pollutants and plastic pollution in the Gulf of California (Mexico)? First ecotoxicological investigation using skin biopsies

The whale shark (Rhincodon typus) is an endangered species that may be exposed to micro- and macro-plastic ingestion as a result of their filter-feeding activity, particularly on the sea surface. In this pilot project we perform the first ecotoxicological investigation on whale sharks sampled in the Gulf of California exploring the potential interaction of this species with plastic debris (macro-, micro-plastics and related sorbed contaminants). Due to the difficulty in obtaining stranded specimens of this endangered species, an indirect approach, by skin biopsies was used for the evaluation of the whale shark ecotoxicological status. The levels of organochlorine compounds (PCBs, DDTs), polybrominated diphenyl ethers (PBDEs) plastic additives, and related biomarkers responses (CYP1A) were investigated for the first time in the whale shark. Twelve whale shark skin biopsy samples were collected in January 2014 in La Paz Bay (BCS, Mexico) and a preliminary investigation on microplastic concentration and polymer composition was also carried out in seawater samples from the same area. The average abundance pattern for the target contaminants was PCBs>DDTs>PBDEs>HCB. Mean concentration values of 8.42ng/g w.w. were found for PCBs, 1.31ng/g w.w. for DDTs, 0.29ng/g w.w. for PBDEs and 0.19ng/g w.w. for HCB. CYP1A-like protein was detected, for the first time, in whale shark skin samples. First data on the average density of microplastics in the superficial zooplankton/microplastic samples showed values ranging from 0.00items/m3 to 0.14items/m3. A focused PCA analysis was performed to evaluate a possible correlation among the size of the whale sharks, contaminants and CYP1A reponses. Further ecotoxicological investigation on whale shark skin biopsies will be carried out for a worldwide ecotoxicological risk assessment of this endangerd species

Whale Sharks Control region raw 506 individuals

This excel dataset can be saved in .fasta - Locations and year of collection are described when available. 'N' means unknown, while '-' indicates gap. Additional sequences can be found on genebank from Castro et al. 2007, but seems to be reversed. Analysis performed in Vignaud et al. 2014 used modified dataset to remove N and large gaps as described in the methods