968 resultados para Baja California, Mexico
Resumo:
Hagfish, often referred to as "slime eels", are familiar to most fishermen as pests that frequently devour fish caught by trap, hook, and gillnet. In the Republic of Korea (ROK or South Korea), however, hagfish are sought after as valuable fish not only for their edible flesh, but also for their skin, which is processed into leather used to make expensive purses, shoes, and other articles. In fact, because of a shortage of hagfish in the waters near the ROK, the leather industry there has started to import hagfish, first from Japan in the mid 1980's, then from the United States starting in 1988. This report describes the nascent fishery for Eptatretus stouti (Pacific hagfish) in California, and includes aspects of its life history. The hagfish industry in the ROK is also briefly described.
Resumo:
Spawning behavior and external features of the larval development were studied in the chitons Mopalia muscosa and M. lignosa during the months of April-June, 1974, at Pacific Grove, California. ... The sequence of events in the development of the two species in the same, though some differences in timing exist.
Resumo:
This paper contains a brief report on the status of the California water supply situation on March 1, 1989, including a review of the antecedent conditions of the past two dry water years.
Resumo:
Pacific sea surface temperatures (SSTs) are examined for their associations with (1) summer rainfall, and (2) the latitude location of the mid-tropospheric subtropical high pressure ridge (STR) in the southwestern United States during 1945 to 1986. Extreme northward (southward) displacements of STR are associated with wet (dry) summers over Arizona and an enhanced (weakened) gradient of SST off the California and Baja coasts. These tend to follow winters marked by positive (negative) phases of the PNA, Pacific/North America, teleconnection pattern. Recent decadal variations of Arizona summer rainfall (1950s wet; 1970s dry) appear similarly related to southwestern United States synoptic circulation and eastern Pacific SSTs.
Resumo:
Upper Pleistocene sediments on the continental slope off Northern California contain alternations of varves and bioturbation produced by fluctuations in intensity of the coastal upwelling system. Stable isotopic analyses of benthic Foraminifera across a particularly well developed varve/bioturbation sequence deposited ~26,000 years ago reveal rapid shifts of ~0.25‰ in δ18O and ~0.4‰ in δ13C. The δ18O shift occurs within a varved section. Based on varve counts, the isotopic change occurred in less than 100 years. Timing and magnitude of the shift coincide with similar shifts observed in almost all other high-resolution δ18O records that have been interpreted as primarily representing global in-volume fluctuations.
Resumo:
Particle flux in the ocean reflects ongoing biological and geological processes operating under the influence of the local environment. Estimation of this particle flux through sediment trap deployment is constrained by sampler accuracy, particle preservation, and swimmer distortion. Interpretation of specific particle flux is further constrained by indeterminate particle dispersion and the absence of a clear understanding of the sedimentary consequences of ecosystem activity. Nevertheless, the continuous and integrative properties of the particle trap measure, along with the logistic advantage of a long-term moored sampler, provide a set of strategic advantages that appear analogous to those underlying conventional oceanographic survey programs. Emboldened by this perception, several stations along the coast of Southern California and Mexico have been targeted as coastal ocean flux sites (COFS).
Resumo:
DSDP Site 480 in the Gulf of California represents a paleoclimatic record of great potential significance. Much of the 152-meter section is varved, which means that proxy records of climatic change can be analyzed with unusual precision on a variety of time scales. In this paper we present pollen and dinoflagellate evidence that suggests that the base of the section is much older than was previously thought. We propose a basal date of between 300,000 and 350,000 YBP.
Resumo:
EXTRACT (SEE PDF FOR FULL ABSTRACT): Tree-ring records from foxtail pine (Pinus balfouriana) and western juniper (Juniperus occidentalis) growing near tree line in the eastern Sierra Nevada, California, show strong correlations with summer temperature and winter precipitation. Response surfaces portraying tree growth as a function of summer temperature and winter precipitation indicate a strong interaction between these variables in controlling growth. ... Above average growth for both foxtail pine and western juniper from AD 1480 to 1570 can be interpreted as indicating an extended period of warm, moist conditions unequalled during the 20th century.
Resumo:
Douglas fir is one of the most important trees in northwestern California. Regional pollen records suggest that it has become prominent only in the late Holocene. The primary cause for this change is probably southward stabilization of the mean airstream.