the humboldt current system of northern and central chile - figema

THE HUMBOLDT CURRENT SYSTEM OF NORTHERN AND CENTRAL CHILEbe one of the strategic energy compounds for the future (they commonly occur below the permafrostshield and in sediments of ocean margins). Gas methane hydrates are abundant on the continentalmargins between Papudo (central Chile) to Valdivia (southern Chile). First evaluations in this areaindicate gas methane hydrate reserves for 10 13 m 3 (Morales 2003). The technology to access thesehydrates is developing fast, and Chile must be part of the advance and innovation processes.Geological oceanography in Chile is poorly developed (although the number of geologists in thecountry is high). Therefore the training of marine geologists and the substantial increase of marinegeological research in Chile remains an important task (and opportunity) for the future (Castillaet al. 2005b).Evaluation of the effects of future climate changeIt is known that greenhouse warming and other human alterations may increase the possibility oflarge and abrupt regional or global changes in climatic events, oceanic circulation (especially relatedto deep-water formation), sea–ice dynamics (Smith et al. 2006), and wind velocity (Bakun & Weeks2004). Future wind increases, due to greenhouse effects, may eventually affect one of the HCS keycharacteristics, such as the rate of upwelling events (Bakun 1990, Bakun & Weeks 2004). Forinstance, an increase of 15% in wind would represent an increase of ~40% in the typical rate (latetwentieth century) of sea upper layer volume replaced per day (water renewal). In the BenguelaCurrent System off Namibia, the present atmospheric greenhouse-related intensification of coastalupwelling appears to be causing the abrupt degradation of the ecosystem (Weeks et al. 2004).Therefore, in a scenario with concentrations of greenhouse gases increasing, climate change (e.g.,pattern of wind increase and intensification of upwelling) along the HCS needs to be surveyedunder a long-term monitoring scheme.HCS frontier research opportunitiesAs pointed out there are several research opportunities along the HCS, such as studies of the OMZand related ecosystems, upwelling and climate change, fishery productivity, co-management, conservationand socio-biophysical approaches to fisheries. In addition there are other very excitingand novel frontier lines of research such as studies of the biogeochemical role of Archaea (Woese& Fox 1977) in the HCS. These organisms are also linked to the OMZ and appear to be particularlyabundant in this system. This line of research has recently started in Chile and needs to bestrengthened.Further topics that extend far beyond the scope of the present review but that appear to berelevant in the present context are linked to socioecology, anthropology and paleo-oceanography.For example, how do the processes occurring in coastal waters of the HCS affect the terrestrialenvironments and human populations along the Pacific coast of South America (past, present andfuture)? Palaeo-oceanography and anthropology can offer exciting insights from the past that willalso help to master future challenges.ConclusionsUpwelling is the major driving force of ecological processes in the HCS by promoting high PPboth in the plankton and in the nearshore benthos. Additional processes influenced by upwellingare transport of propagules and biogeochemical processes. Besides their high nutrient concentrations,one main feature of the upwelled waters from the HCS along the Chilean coast is that theyhave low concentrations of dissolved oxygen. This restricts vertical migration of most zooplankters,including of larvae, thereby affecting dispersal. Furthermore, the low oxygen concentrations drive303