Distribution and feeding habitat characterization of whale sharks Rhincodon typus in a protected area in the north Caribbean Sea

Abstract

The relationship between the distribution of the whale shark Rhincodon typus and hydrobiological variables in the Caribbean Sea during 2005-2009 was analysed. Monthly trips were made to the R. typus aggregation area during the months when this species is present in the region (May to September) to record sightings and hydrological data and to collect samples to determine nutrients, chlorophyll a (Chl a) and zooplankton biomass. A total of 2104 R. typus were counted and three zones of high abundance were identified: Cabo-Catoche, Contoy (both within the Whale Shark Biosphere Reserve, WSBR) and the zone knows as Afuera. The zones of greatest R. typus density within the WSBR were characterized by high Chl a concentrations (median: 1·1 mg m , interpercentile range: 0·5-1·8 mg m ) and high nutrient concentrations, such as ammonium (median: 2·5 µmol l , interpercentile range: 0·5-6·4 µmol l ), due to the influence of local upwelling. A generalized additive model (GAM) was used to explore the relationship between R. typus distribution and the environmental variables inside WSBR. Zooplankton biomass was the most influential environmental variable, supporting the close relationship between R. typus distribution and biological productivity. Copepods were the dominant zooplankton group within the WSBR. In the Afuera zone, there were large R. typus aggregations (>80 individuals) associated with zooplankton dominated by fish eggs and significantly higher mean ± s.d. biomass (3356·1 ± 1960·8 mg m ) compared with that recorded inside the WSBR (103·5 ± 57·2 mg m ). The differences among zones generated changes in R. typus distribution patterns and provided opportunities to develop local management strategies for this species.

Environmental factors influencing aggregation of manta rays (Manta birostris) off the northeastern coast of the Yucatan Peninsula

“…We included sea surface temperature in our analysis because it has been correlated with the distribution of planktivorous elasmobranchs (Dewar et al, 2008;Rowat, Gore, Meekan, Lawler, & Bradshaw, 2009;McKinney, Hoffmayer, Wu, Fulford, & Hendon, 2012;Sequeira, Mellin, Bradshaw, Rowat, & Meekan, 2012;Sequeira, Mellin, Fordham, Meekan, & Bradshaw, 2013;Rohner et al, 2013). During the study period, the temperature was within the optimum temperature range recorded for manta rays (Dewar et al, 2008;Clark, 2010;Graham et al, 2012) and similar to temperatures recorded previously for the study area (Merino, 1997;Cárdenas-Palomo et al, 2015). High abundance ranges from late spring (May) through late summer, generally with a peak in July through August, when mean sea surface temperatures are >26°C.…”

“…Services are provided to observe and swim with whale sharks and manta rays, as both aggregate in large numbers in the area (Graham et al, 2012). Most research in the area focuses on whale sharks (Cárdenas-Palomo, Herrera-Silveira, & Reyes, 2010;De la Parra-Venegas et al, 2011; Parra, 2013; Cárdenas-Palomo, Herrera-Silveira, Velázquez-Abunader, Reyes, & Ordonez, 2015;Hacohen-Domené et al, 2015), as this area is one of the largest whale shark aggregation sites in the world (De la Parra-Venegas et al, 2011;Hueter et al, 2013).…”

Phytoplankton blooms associated with upwelling at Cabo Catoche

“…Over the Yucatan continental shelf, these northerly winds (known colloquially as "Los Nortes") have the capacity to affect the ocean-atmosphere heat fluxes, reducing oceanic heat (Hernández -Téllez et al, 1993, Zavala-Hidalgo et al, 2014. Nutrient concentrations of 0.7-16.5 µmol L −1 nitrate, 0.5-38.4 µmol L −1 ammonium, 0.1-2.4 µmol L −1 phosphate, and 2.6-37.8 µmol L −1 silicate have been reported (Cárdenas-Palomo, 2007;Cárdenas-Palomo et al, 2015;Reyes-Mendoza, 2010). Chlorophyll-a concentrations (Chl-a) have been reported from 0.5 to 6.6 mg m −3 and zooplankton biomass between 37 and 222 mg m −3 .…”

“…This has strong implications for the trophic web of the pelagic ecosystem and artisanal fisheries (Merino-Virgilio et al, 2014). Finally, this productivity is linked to high biodiversity in the Cabo Catoche region composed of numerous fish species, octopus, turtles, manta rays and whale shark populations, which are exploited by fisheries and ecotourism industries (Piñeiro et al, 2001;Ardisson et al, 2011;Ramírez-Macías et al, 2012;Cárdenas-Palomo et al, 2015).…”

Polycyclic aromatic hydrocarbons in the cestode Oncomegas wageneri parasite of Mexican flounder Cyclopsetta chittendeni

“…For this analysis, a Pearson's correlation matrix was used to test for collinearity. A value of R ≥ 0.7 was established as a decision criterion for discarding those variables with collinearity problems (Zar 1999;Cárdenas-Palomo et al 2015). The link function (η = μ) was selected considering the following two criteria: highest deviance explained and lowest AIC value (Burnham and Anderson 2002).…”