Building Ocean Science Partnerships The United States and Mexico Working Together (1999) / Chapter Skim
Currently Skimming:
2 Examples of Promising Science Programs and Projects
2 Examples of Promising Science Programs and Projects
Pages 15-64
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From page 15... ...
In the development of other binational ocean science activities, they should pass the test of being studies that are (1) of unique scientific concern to scientists in the United States and Mexico in waters adjacent to or significantly influenced by these nations and (2)
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From page 16... ...
In planning research on these topics, it should be recognized that insights can be gained not only by research within individual regions, but also by comparative studies among the three regions. PACIFIC OCEAN AND GULF OF CALIFORNIA REGIONS Oceanographic Setting Pacific Ocean The Pacific Ocean region shared by the United States and Mexico is dominated by the California Current, which flows southward as the eastern boundary current of the subtropical North Pacific Ocean (Figure 2.1~.
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Colorado River ~E~enada ~ \ \ Islagngel de La Guarda \. Isle Tiburon Cat\ lf ureas ~ ~ ' TO ~ ~ Hi, Pulmo .5, Cabo San Lucas Sir \tSan Carla: 0~\: Topolobampo Abundant marine mammals and Biosphere Reserve of the Upper Gulf of California Guaymas Basin hydrothermal vents Major fish landing ports Northernmost reef in the Eastern Pacific (Cabo Pulmo)
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From page 18... ...
More recently, there has been progress in studying more complex phenomena such as · the nature of~ the upwelling front and associated jets and eddies in the case where the front lies seaward of the edge of the continental shelf; · the relation between coastal upwelling jets and the core of the California Current; · the evolution of jets and eddies through an upwelling season; · the circulation in regions of more complex bottom topography (see the special issue of the Journal of Geophysical Research, 1991~; and · the influence that wind forcing, coastal irregularities, and the variation of the Coriolis parameter have on the generation of many of the observed features of the California Current System (Batteen, 1997~.
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From page 19... ...
limit of the California Current System along Baja California and in the Gulf of California. One example of a large-scale feature that has not been sampled adequately is the California Undercurrent.
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Gulf of California The virtually land-locked Gulf of California is an extreme physical and geological environment, characterized by such major features and processes as · large tidal range, reaching 10 m during spring tides, causing extensive drying and flooding of the nearshore regions; · relatively pristine and arid land areas; · strong tidal streams and strong vertical mixing forced by them; · wide shallow-water deposits of fine sediments in the Colorado River delta; · local wind forcing of both drift currents and wave-induced mixing; · strong resuspension of seabed material, probably correlated with tidal and wind-induced mixing; and · circulation that may distribute particulate matter across the shelf, reaching the deeper basins near the middle of the gulf. Variability of Fisheries The social and economic concerns related to studies of the California Current System are obvious.
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From page 21... ...
and sea surface temperature (SST) and air temperature (panel B)
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From page 22... ...
, abalone, and other benthic species (Phillips et al., 1994; Vega et al., 1997~. Regime shifts and the associated changes in abundance and distribution of critical prey species such as sardines and anchovies have profound influences on the population dynamics and status of marine mammals and seabirds.
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From page 23... ...
More specifically, there are a number of important scientific questions related to the physical dynamics of the California Current System and how the physical system affects the population dynamics of commercially important fish species. The following are some examples: · What is the nature of the climatic and oceanic variations, and what drives them?
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From page 24... ...
task. The only way regime shifts in the California Current System can be studied is within the context of a larger regional or global program, for example, through the establishment of a regional ocean observing system or through links with the Climate Variability and Predictability (CLIVAR)
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From page 25... ...
The coastal impacts of NAO events are basically unexplored; however, it has been established that sea surface temperature (SST) variability in the Caribbean Sea and Gulf of Mexico is linked to anomalous SSTs in the tropical Atlantic Ocean associated with the NAO.
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are situated exclusively in the coastal lagoons and embayments of the Pacific coast of Baja California. In addition, populations of other species, such as humpback and blue whales, remain quite low and continue to receive protection under national and international agreements for endangered species.
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From page 27... ...
The potential exists to link marine mammal and seabird studies with investigations of commercially important prey species such as anchovies, sardines, and squid. The relatively calm waters and the high concentrations of marine mammals and seabirds in the Pacific Ocean and Gulf of California provide a unique opportunity to apply these new techniques to pelagic species that have been difficult to study.
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From page 28... ...
Such collaborative research is already occurring in the Gulf of California for example, on slope basins northeast of La Paz involving the Autonomous University of Baja California Sur and the University of Southern California, but similar research should also be conducted in the California Borderland. Comparative studies of processes occurring in these two regions would improve our understanding and use of these sensitive climatic indices.
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From page 29... ...
border area is used heavily for transportation, recreation, and commercial fishing and is the final repository of many pollutants, threatening both marine ecosystems and coastal human populations. The impacts of pollution include contamination and disease in fish and shellfish populations, changes in kelp beds and other ecosystems, changes in plankton populations due to nutrient enrichment by wastewater, and contamination of sediments and organisms with toxic material and bacteria in wastewater and storm runoff.
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From page 30... ...
Concentrations of suspended particulate matter reach 130 milligrams per liter (mg/L) near the Baja California side of the upper gulf, decreasing to 5 mg/L toward the center of the northern gulf (Garcia de Ballesteros and Larroque, 1974~.
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From page 31... ...
Answers to this question have significant implications both for the future of natural marine habitats and for the future of human activities on the Gulf of California coast. Tectonic Development of the California Borderland and the Gulf of California The Continental Borderland to the west of Baja California and Southern California occupies a unique and strategic location critical to understanding the crustal evolution of the Californias and the Pacific Plate-North American Plate boundary (Krause, 1965~.
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From page 32... ...
a rotation of 90 degrees of one of these segments over the present area of the northern Borderland to become the present east-west trending western Transverse Ranges, as the western end of the range moved northward faster than the eastern end; and 3. a reorganization of the tectonics of the region that resulted in the present structure of the Borderland and the Californias, the opening of the Gulf of California, and the capture by the Pacific Plate of Baja California and all of Southern California west of the San Andreas Fault.
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From page 33... ...
seafloor sampling, core analysis, isotope dating, and petrologic studies to assess offshore and nearshore rock composition, stratigraphy, and the rates and dates of sedimentation, volcanism, and Borderland deformation and breakup, as well as changes in the climate and the California Current System. Observations of these three types would provide an integrated data set to allow detailed interpretation of the fundamental processes involved in crustal evolution, crustal extension, and plate boundary development of this critical segment of the continental margin of the Californias.
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From page 34... ...
Some primary geological aspects relevant to the formation of the gulf are possible influences on the gulf's location and development: the batholith* in Baja California may have controlled the definition of the western margin of the rift by acting as a rigid block; perhaps the Cretaceous trans-arc environment occupied the position of the modern gulf, and/or the later Miocene volcanic arc helped to determine the present position of the gulf.
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From page 35... ...
Chemical distributions are dominated by complex interactions between migrating hydrothermal fluids and both inorganic and organic sedimentary materials (Gieskes et al., 1982~. In addition to the deep sediment-smothered basins of the gulf, there are numerous nearby shallow-water areas such as Punta Banda, Baja California, where hydrothermal activity and the microbiology of thermophilic marine bacteria can be studied at depths of approximately 30 m (Vidal, 1980; Vidal and Vidal, 1980; Vidal et al., 1982: Vidal et al., 1978, 1981~.
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From page 36... ...
revealed the presence of living benthic foraminifera in the Guaymas Basin hydrothermal vents. Studies of sedimentsmothered vents in the Gulf of California offer opportunities for significant new findings and provide a natural impetus for interdisciplinary and multinational oceanographic research.
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From page 37... ...
Potential studies related to geology and geophysics include formation of massive sulfide ore bodies; petroleum formation from recently produced organic matter; hydrothermal fluid migration through thick sediments; controls on temporal variability of venting processes; and comparison of seismic activity at sediment-smothered versus open-ocean vents. Biotechnology and Toxicology: Sediment-smothered vents may harbor unique organisms that could have useful commercial properties or could help in the study of the effects of toxic materials on marine organisms.
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From page 38... ...
Thus, the geographic scope of the Gulf of Mexico and adjacent waters of concern here includes the region that has begun to be referred to as the IntraAmericas Sea (IAS) , a term that originated with an IOCARIBE working group of the Sub-Commission for the Caribbean and Adjacent Regions of the Intergovernmental Oceanographic Commission and encompasses the Caribbean Sea, the Gulf of Mexico, Straits of Florida, Antilles and Guyana Currents, and because of biogeographic considerations, even Bermuda.
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The upper ocean waters of the IAS are uniquely warm, clear, and pristine, flowing from east to west into the Caribbean Sea from the tropical and subtropical Atlantic Ocean on its eastern boundary. This water transits the Caribbean Sea basins from east to west and exits the Caribbean Sea through the Yucatan Strait into the Gulf of Mexico.
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In the Caribbean Sea, the Panama-Colombia Gyre (D) was a persistent and dominant feature, which varied from Day 670 to Day 740.
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EXAMPLES OF PROMISING SCIENCE PROGRAMS AND PROJECTS 26.0°N ~n ~ 24 0 23.0 21 0 26.0°N 25.0 24.0 23.0 22.0 21.0 20.0 19.0 18.0 EE -98.0 -97.0 -96.0 -95.0 -94.0 -93.0°W FIGURE 2.5 Western boundary currents and baroclinic circulation in the western surface Gulf of Mexico during (a) March 1985 and (b)
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From page 42... ...
These focus on the physics, geology, geochemistry, biology, and environmental quality of the coastal zone, continental shelf-slope, and abyssal plain ecosystems of the IAS (including oil, gas, and brine seeps)
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From page 43... ...
Exchanges of water between the continental shelf and the open ocean are present along the shelfbreak, probably at discrete points associated with topographic features (e.g., submarine canyons) and at discrete times associated with transient (wind-driven and eddy-driven)
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From page 44... ...
Conversely, the flux of oceanic water onto the continental shelf, driven by the colli sion of Loop Current rings, has been shown to be the precursor of intense vertical mixing and the formation of Gulf Common Water in the western Gulf of Mexico (Vidal et al., 1988, 1992, 1994b,c)
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From page 45... ...
ring-continental slope and ring-ring interactions; · ring collisions with the continental margin and the formation of alongshelf currents; · origin of the gulf's western boundary current (is it wind-driven or does it result from the decay of colliding Loop Current rings in the western gulf or bother; · ring bifurcations and angular momentum conservation; the proliferation of cyclonic-anticyclonic pairs and their influence on mass-volume exchanges between the gulf's continental shelf and oceanic waters; · water mass formation and mixing in the gulf, including the influence of wind-driven mixing versus ring-slope and ring-ring interactions; and · vertical transport balance associated with the distribution of relative potential vorticity and its influence on the intermediate and deep mean circulation of the gulf. Although these research issues are focused on processes occurring in the IAS, they are also relevant to understanding physical phenomena generic to the global ocean (e.g., eddy shedding, carbon dioxide [CO21 removal and climate change, western boundary current generation in response to weather events, and sea-level rise)
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From page 46... ...
, is overwhelmingly barotropic.t Both the upper and the lower layers in the gulf are strongly affected by fluctuations of the Loop Current, and there is evidence that the deep-water fluctuations become progressively more decoupled from upper layer currents as the topographically trapped Rossby waves and warm eddies propagate into the western gulf basin (Hamilton, 1990; Vidal et al., 1990, 1994b,d)
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From page 47... ...
Ongoing studies of the circulation of the western gulf have incorporated numerical modeling of Loop Current intrusions and eddy shedding (Hurlburt and Thompson, 1980, 1982; Dietrich and Lin, 1994~; interactions of Loop Current anticyclones with bottom topography and the western gulf boundary (Smith and O'Brien, 1983; Smith, 1986; Shi and Nof, 1993, 1994~; satellite infrared imagery and hydrography (Vukovich et al., 1979; Brooks and Legeckis, 1982; Vukovich and Crissman, 1986; Biggs and Muller-Karger, 1994~; satellite positioning of surface drifters seeded within Loop Current rings (Kirwan et al., 1984a,b; Lewis and Kirwan, 1985; SAIC, 1988; Lewis et al., 1989~; regional hydrography and baroclinic circulation studies (Nowlin, 1972; Molinari et al., 1978; Elliott, 1979, 1982; Merrell and Morrison, 1983; Merrell and Vazquez, 1983; Hofmann and Worley, 1986; Vidal et al., 1988, 1990, 1992, 1994a,b,c) ; and satellite altimetry measurements (Forristall et al., 1990; Leben et al., 1990; Biggs and Sanchez, 1997~.
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· When anticyclonic Loop Current rings collide with the western gulf boundary, do they generate western boundary currents and current jets parallel and normal to the shelf break, respectively?
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From page 49... ...
concluded that although the work done by the wind stress may generate part of the available potential energy of the western boundary flow anticyclone, the primary source of available potential energy must be the western-moving anticyclonic rings that separate from the Loop Current. Vidal et al.
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From page 50... ...
The major source of energy for vertical mixing in the western gulf is believed to be supplied by ring-slope and ring-ring interactions (Vidal et al., 1990, 1992, and 1994b,c,d)
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From page 51... ...
Anticyclonic rings derived from the Loop Current occasionally impact the Louisiana shelf west of the delta but usually drift to the western gulf where they collide with the continental shelf slope, resulting in an exchange of about 18 x 106 m3 per ring of oceanic and shelf waters (Vidal et al., 1994b) and a large input of particulate organic carbon available to benthic organisms (Escobar and Soto, 1997~.
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From page 52... ...
At the southern entrance to the Caribbean Sea, beginning about 10°N, the entering coastal flow contains fresh water from the Amazon and Orinoco Rivers. The Amazon's nutrients are mostly depleted
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From page 53... ...
On the broad shelves of the Caribbean Sea the sediments are predominately carbonate sands containing highly diverse invertebrate assemblages of relatively low biomass. The species composition of a "Caribbean Fauna" is bounded on the north by a series of faunal boundaries such as the northern boundary of reef-forming corals in the Gulf of Mexico.
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From page 54... ...
. A basic theme of the research is to gain better understanding of carbon cycling in relation to continental shelf shrimp
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From page 55... ...
Sedimentary Dynamics and Environmental Impacts on the Coastal and Oceanic Zones of the Gulf of Mexico Land-ocean interactions affecting the marine sedimentary environment in the western Gulf of Mexico are complex and vary among regions of the coastal ocean. These variations are due to differences in (1)
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From page 56... ...
Marine Environmental Quality Binational research and monitoring could contribute to reducing the effects of marine pollution in the IAS, including pollution from nutrients, toxic materials, oil, and debris from land and marine sources. The northern Gulf of Mexico has been studied extensively with respect to its chemical constituents.
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From page 57... ...
. One important conclusion is that approximately 50% of the oil in the IAS comes from the Atlantic Ocean.
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From page 58... ...
Joint research on biomarkers and validation of environmental indicators in tropical marine ecosystems, which are more diverse and more stable climatically, is also highly desirable. This kind of information would be very valuable for coastal zone management.
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, including contaminants such as persistent organic pollutants (pesticides and petroleum hydrocarbons) , sewage, and trace metals.
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From page 60... ...
, basic studies in marine ecology that must precede a major harvesting program, aquaculture research, and studies in marine biodiversity. Mexican researchers and funding agencies might wish to examine the feasibility of interdisciplinary research programs related to marine natural products chemistry, learning from the successes and mistakes experienced by U.S.
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From page 61... ...
However, such research has its detractors because commercial fishing and destruction of marine habitats for urban and industrial development are among the principal factors contributing to the reduction of marine biodiversity. Research on marine biodiversity requires significant financial support for taxonomic studies on both sides of the border.
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From page 62... ...
The opportunity to sample marine microorganisms, including extreme thermophilic bacteria from the geothermal vent systems and extreme halophiles from salt ponds, can significantly expand the biomedical potential of Gulf of California organisms. The fledgling marine biotechnology industry has shown considerable interest in extreme thermophilic marine bacteria because they produce enzymes that are stable and efficient at high temperatures and pressures and are therefore attractive for use in industrial processes.
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From page 63... ...
Both the organizers and the participants were surprised at the diversity of existing research. A similar U.S.-Mexico conference on marine biotechnology could be used to initiate binational collaborations in this field.
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From page 64... ...
64 BUILDING OCEAN SCIENCE PARTNERSHIPS The area of joint U.S.-Mexican interest spans extensive tropical and subtropical regions, where it is naturally easier to detect trends in long time series of some ocean variables because of the reduced synoptic-scale and seasonal noise relative to the situation at high latitudes. This advantage should be used in the selection of sites and variables to be studied.
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