HR: 10:40h
AN: OS32A-02    [Abstracts]
TI: Hydrography of Bahia Todos Santos, Baja California: Results of more than twenty five years of investigations.
AU: * Bustos-Serrano, H
EM: hbustos@uabc.mx
AF: UNIVERSIDAD AUTONOMA DE BAJA CALIFORNIA, FACULTAD DE CIENCIAS MARINAS, KM 103 CARRETERA TIJUANA-ENSENADA, ENSENADA, BC 22890, Mexico
AU: Canino-Herrera, S R
EM: rcanino@uabc.mx
AF: UNIVERSIDAD AUTONOMA DE BAJA CALIFORNIA, FACULTAD DE CIENCIAS MARINAS, KM 103 CARRETERA TIJUANA-ENSENADA, ENSENADA, BC 22890, Mexico
AU: Morales-Chavez, R
EM: metanicabc@yahoo.com.mx
AF: UNIVERSIDAD AUTONOMA DE BAJA CALIFORNIA, FACULTAD DE CIENCIAS MARINAS, KM 103 CARRETERA TIJUANA-ENSENADA, ENSENADA, BC 22890, Mexico
AU: Martinez-Garcia, G M
EM: guimar1956@hotmail.com
AF: UNIVERSIDAD AUTONOMA DE BAJA CALIFORNIA, FACULTAD DE CIENCIAS MARINAS, KM 103 CARRETERA TIJUANA-ENSENADA, ENSENADA, BC 22890, Mexico
AB: The first study of Bahia Todos Santos (BTS) was reported by Walton in 1955. We conducted oceanographic studies in BTS since 1979. The BTS has a connection with a coastal lagoon named Estero de Punta Banda (EPB), two islands at the western portion and the Port of Ensenada. The general hydrographic characteristics are: In winter the water became homogeneous, less saline (<33.4) and with low stability. During spring and summer a hydrographic structure of three layers is noticed. The deepest layer is composed of the southern California water mass with a relatively high salinity (>33.6) low temperature (13°C), low oxygen (~3mL L-1) and rich in nutrient concentration. The isothermal top layer has relatively high temperature (>17°C) and oxygen concentration (>6mL L-1). The intermediate transition layer (seasonal thermocline) has minimum salinity, maximum oxygen and high stability. During fall there is distribution of heat from the surface layer to the entire water column. The thermic waves propagate with decrease amplitude in ~3 months, from surface to bottom water. The California Current flow generally southward off the western United States and northern Mexico and is one of the major coastal upwelling of the word oceans. The upwelling events in BTS appear regularly at the SW portion and were typically characterized by an increase in pCO2, decrease of O2, increase of nutrients and a lower temperature. Upwelling activity increases surface nutrient availability causing rise in the primary productivity and hence increased zooplankton biomass. The annual upwelling event which had a maximum strength on May, the seasonal warming and cooling, and the water advection were the dominant modifying processes for the variability of seawater characteristics. Higher salinities are located close to the coastline and lower off the bay. The levels of oxygen, alkalinity, pH and chlorophyll indicate that the maximum concentration of phytoplankton is located at the center of the bay. The nitrification support the primary productivity and the NO3 levels were below detection limits; the N/P ratio in 2005 was from 10 to 25; and for 2006 was below 5. There is a net enrichment of anthropogenic nutrients at BTS. The heavy metals and pesticides studies started since the early 80's with problems still to solve for Tl, Cd. There is a net Pb enrichment and higher Cr concentrations at the NE of the bay. The EPB is a wetland ~7 Km. long located at the SE part of the BTS. The EPB is a net source of DIP (deltaDIP = +0.13 mmol m-2 day-1), that brings agricultural runoff to the BTS. It is typically a hypersaline system during summer and a net heterotrophic (p-r = -14 mmol m-2 day-1), and a net denitrifying (nfix-denit = -2.1 mmol m-2 day-1) system. Some anomalies were in 2005 the presence of a huge red tide observed inside BTS (about 50% of the bay) that last for more than six months, this HAB's has killed many fishes (anoxia) and marine mammals. The hydrographic conditions during the red tide were, temperature anomalies higher than 2°C above normal; high nutrient concentration above the normal. In 2006 the values were normal again. The Port of Ensenada, increased in size and activities (tourism, transportation, coastguards for national security, cement industry, research) these developments generate some management problems, like the beach and coastline modification. The aground of the APL Panama, activates the management agencies to prevent and control pollution.
DE: 4223 Descriptive and regional oceanography
DE: 4243 Marginal and semi-enclosed seas
DE: 4251 Marine pollution (0345, 0478)
DE: 4277 Time series experiments (1872, 3270, 4475)
DE: 4845 Nutrients and nutrient cycling (0470, 1050)
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly