Oceanographic implications of the Cabo Catoche (Northeast Yucatan) upwelling and its effects on the coastal ecosystem
Abstract
The coasts of the world where upwelling events occur are intrinsically related to the human population, mainly because of their large fisheries, socioeconomic repercussion and implications concerning the health of the ecosystem. In the northeast of the Yucatan Peninsula occurs an upwelling event known as the Yucatan upwelling (YU) associated with the current of the same name. The mechanisms that generate the YU are still under discussion. In terms of seasonality it is agreed that this is annual, occurring between April and September. During spring and summer, the northeast coast of the Peninsula between CaboCatoche and Isla Contoy becomes a productive and diverse pelagic ecosystem, unique to the region. It is classified as a priority marine zone host to close to 59 species protected by the national laws. It is also recognized as an important priority marine site because of its fishery. Also, the largest global aggregation of whale sharks, the world's biggest fish, is found at this site. There is a strong connection between the physical and the biological components of the system, however the coastal extent, seasonality, and magnitude of these processes need to be determined. Therefore an in-situ study was designed in the coastal region of CaboCatoche, where a 50 km transect was positioned along shelf and another across shelf 20 km, where water was collected to determine nutrient concentrations and CTD profiles were casted during the summer of 2007, 2008 and 2011. Two acoustic profilers were installed 12 km from the coast, which recorded currents and temperature by 2 years. Another profiler located 17 km from the coast to recorded data by 8 years. Atmospheric pressure and temperature were measured, as a wind fields from NOAA. Maps were created for the vertical distribution of temperature (18-31°C), salinity (35-38 psu), density (22-27 kg/m3) and chlorophyll (0.05-12.7 mg/m3). Frequency periods were estimated for temperature, currents, wind and atmospheric pressure using spectral analysis and wavelets. In order to establish associations between the physical, chemical and biological variables multivariate analyses were performed. Based in temperature the results indicate that the upwelling occurs in pulses of two different time periods; 2-4 days and the other 8 to16 days, from March to September, associated with a decrease in sea level (-0.008±0.03 m) and variation in the V component of the current (0.007±0.006 m/s to the north). On the year the dominant tides are diurnal K1, O1 and semidiurnal M2, S2, and the U and V current component had the same periodicity during upwelling, but with not upwelling V hasn't it. The atmospheric temperature decreases the water column temperature near 10 degree during not upwelling, as also in upwelling but by other mechanisms. It is yet not possible to determine the mechanism responsible for this periodicity, however it is believed to be due to a combination of wind and Yucatan current variability. The Primary production has a response time of 2 to 3 days following the onset of the pulse and the Cla-a have an increase ten times more than the mean value.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSMOS51A..06R
- Keywords:
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- 4217 OCEANOGRAPHY: GENERAL / Coastal processes;
- 4512 OCEANOGRAPHY: PHYSICAL / Currents;
- 4815 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Ecosystems;
- structure;
- dynamics;
- and modeling;
- 4855 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Phytoplankton