A. Mejia-Trejo - Academia.edu (original) (raw)

Papers by A. Mejia-Trejo

An exploration of the population characteristics and behaviours of the white shark in Guadalupe Island, Mexico (2014–2019): Observational data from cage diving vessels

Aquatic Conservation: Marine and Freshwater Ecosystems, 2021

1. In the eastern North Pacific, the Guadalupe Island Biosphere Reserve (GIBR) is one of the most... more 1. In the eastern North Pacific, the Guadalupe Island Biosphere Reserve (GIBR) is one of the most renowned white shark (Carcharodon carcharias) aggregation sites studied to date, and important tourism activity has been developed in the thereserve.2. This study used tourist-based cage diving activities to biologically monitor white sharks from 2014 to 2019 within the GIBR.3. The data indicated a gradual increase in the overall abundance of white sharks with an age-structure shift, as young of the year and juvenile sharks were more prevalent during the latter part of the study period (2016–2019).4. The arrival of young of the year and juvenile white sharks coincided with regional changes in oceanographic conditions off California and Baja California.5. The arrival of adult female white sharks coincided with the seasonal peak in elephant seal abundance.6. Records of high-risk white shark behaviors, a shift to sharks of younger ages, and the high prevalence of small individuals during cage diving activities supports the need for the continued revision of tourism operational protocols.7. This study highlights the importance of white shark biological monitoring to identify threats and challenges to the growing tourism industry and the management of the species in Guadalupe Island and in other aggregation sites.

Estuarine, Coastal and Shelf Science, 2011

The role of coastal lagoons and estuaries as sources or sinks of inorganic carbon in upwelling ar... more The role of coastal lagoons and estuaries as sources or sinks of inorganic carbon in upwelling areas has not been fully understood. During the months of MayeJuly, 2005, we studied the dissolved inorganic carbon system in a coastal lagoon of northwestern Mexico during the strongest period of upwelling events. Along the bay, different scenarios were observed for the distributions of pH, dissolved inorganic carbon (DIC) and apparent oxygen utilization (AOU) as a result of different combinations of upwelling intensity and tidal amplitude. DIC concentrations in the outer part of the bay were controlled by mixing processes. At the inner part of the bay DIC was as low as 1800 mmol kg À1 , most likely due to high water residence times and seagrass CO 2 uptake. It is estimated that 85% of San Quintín Bay, at the oceanic end, acted as a source of CO 2 to the atmosphere due to the inflow of CO 2 -rich upwelled waters from the neighboring ocean with high positive fluxes higher than 30 mmol C m À2 d À1 . In contrast, there was a net uptake of CO 2 and HCO 3 À by the seagrass bed Zostera marina in the inner part of the bay, so the pCO 2 in this zone was below the equilibrium value and slightly negative CO 2 fluxes of À6 mmol C m À2 d À1 . Our positive NEP and DDIC values indicate that Bahía San Quintín was a net autotrophic system during the upwelling season during 2005.

Aquat Conservation Mar Freshw Ecosyst, 2021

A numerical study is described of the three-dimensional circulation in Alcatraz Bay, Gulf of Cali... more A numerical study is described of the three-dimensional circulation in Alcatraz Bay, Gulf of California, México, using the GCOM model. The model solves the three-dimensional momentum equations over a grid that adapts the bottom surface and the coastline. In order to elucidate the effect of stratification as well as the effect of flow-topography interactions on the flow, results are shown for density and velocity fields under different flow conditions.

Journal of Coastal Research, 2011

DELGADO-GONZÁ LEZ, O.E.; JIMÉ NEZ, J.A.; ESPEJEL, I.; FERMAN-ALMADA, J.L.; MARTÍNEZ-DÍAZ-DE-LEÓ N... more DELGADO-GONZÁ LEZ, O.E.; JIMÉ NEZ, J.A.; ESPEJEL, I.; FERMAN-ALMADA, J.L.; MARTÍNEZ-DÍAZ-DE-LEÓ N, A.; MEJÍA-TREJO, A., and SEINGIER, G., 0000. Aquaculture potential of Mexican coasts. Journal of Coastal Research, 00(0), 000-000. West Palm Beach (Florida), ISSN 0749-0208.