Sea surface reconstruction for sediments of the California continental margin

Organic matter in sediment samples from three ODP sites (Ocean Drilling Program Leg 167) that form a south-north transect was investigated to reconstruct the paleoclimatic and oceanographic conditions on the California continental margin during the last 160 kyr. Alkenone-derived paleosea surface temperatures (SST) are 3 to 6°C colder in glacial stages and reveal a clear relationship with global climate changes; the differences are greater in the north. Latitudinal SST comparison exhibits water mixing of the colder California Current with warmer waters from the south, particularly in the southern central California borderland area. Organic matter accumulation on the California continental margin indicates an interplay between climatic and atmospheric glacial-interglacial variations and spatially and temporally changing nutrient availability along the California coastline. Climatic and atmospheric dependent circulations apparently caused variations in the intensity of coastal upwelling along the southern central California margin and this suggests, due to the close connection of the California Current to the local wind patterns, that the California Current was weaker during glacial and stronger during interglacial periods.

Corg, CaCO3, bulk densities, accumulation rates and ages of ODP Leg 167 sites and three piston cores, California margin

Sediments from five Leg 167 drill sites and three piston cores were analyzed for Corg and CaCO3. Oxygen isotope stratigraphy on benthic foraminifers was used to assign age models to these sedimentary records. We find that the northern and central California margin is characterized by k.y.-scale events that can be found in both the CaCO3 and Corg time series. We show that the CaCO3 events are caused by changes in CaCO3 production by plankton, not by dissolution. We also show that these CaCO3 events occur in marine isotope Stages (MIS) 2, 3, and 4 during Dansgaard/Oeschger interstadials. They occur most strongly, however, on the MIS 5/4 glaciation and MIS 2/1 deglaciation. We believe that the link between the northeastern Pacific Ocean and North Atlantic is primarily transmitted by the atmosphere, not the ocean. Highest CaCO3 production and burial occurs when the surface ocean is somewhat cooler than the modern ocean, and the surface mixed layer is somewhat more stable.

El cooperativismo y la financiación agrícola en Baja California, México (1930-1950) : Una aproximación inicial

Para la teoría neoclásica convencional el funcionamiento de los mercados de crédito soporta dos dificultades básicas: la información imperfecta o asimétrica y la selección adversa del prestatario aunada al riesgo del no pago. En el otro extremo, más heterodoxo, el colectivismo, el capital social y la formación de redes informales y sociedades de crédito suelen reducir los costes de transacción ligados al problema de la financiación. Este tipo de organización facilita el desenvolvimiento del cooperativismo en la economía. En México, después de la Revolución y la conformación de un régimen político autoritario y vertical, el cooperativismo se constituyó en uno de los referentes de la organización campesina para conseguir crédito de la banca pública y privada. En el noroeste del país y la península de Baja California, la existencia de cooperativas pesqueras, ganaderas, agrícolas y de transporte significó un despunte de la actividad económica y uno de los canales del desarrollo de la región. El propósito del artículo es perfilar qué tipo de cooperativismo se articuló en el Distrito Norte de la península de Baja California y qué tipo de relación guardó con el movimiento cooperativista nacional entre 1930 y 1950

El cooperativismo y la financiación agrícola en Baja California, México (1930-1950) : Una aproximación inicial

Para la teoría neoclásica convencional el funcionamiento de los mercados de crédito soporta dos dificultades básicas: la información imperfecta o asimétrica y la selección adversa del prestatario aunada al riesgo del no pago. En el otro extremo, más heterodoxo, el colectivismo, el capital social y la formación de redes informales y sociedades de crédito suelen reducir los costes de transacción ligados al problema de la financiación. Este tipo de organización facilita el desenvolvimiento del cooperativismo en la economía. En México, después de la Revolución y la conformación de un régimen político autoritario y vertical, el cooperativismo se constituyó en uno de los referentes de la organización campesina para conseguir crédito de la banca pública y privada. En el noroeste del país y la península de Baja California, la existencia de cooperativas pesqueras, ganaderas, agrícolas y de transporte significó un despunte de la actividad económica y uno de los canales del desarrollo de la región. El propósito del artículo es perfilar qué tipo de cooperativismo se articuló en el Distrito Norte de la península de Baja California y qué tipo de relación guardó con el movimiento cooperativista nacional entre 1930 y 1950

El cooperativismo y la financiación agrícola en Baja California, México (1930-1950) : Una aproximación inicial

Para la teoría neoclásica convencional el funcionamiento de los mercados de crédito soporta dos dificultades básicas: la información imperfecta o asimétrica y la selección adversa del prestatario aunada al riesgo del no pago. En el otro extremo, más heterodoxo, el colectivismo, el capital social y la formación de redes informales y sociedades de crédito suelen reducir los costes de transacción ligados al problema de la financiación. Este tipo de organización facilita el desenvolvimiento del cooperativismo en la economía. En México, después de la Revolución y la conformación de un régimen político autoritario y vertical, el cooperativismo se constituyó en uno de los referentes de la organización campesina para conseguir crédito de la banca pública y privada. En el noroeste del país y la península de Baja California, la existencia de cooperativas pesqueras, ganaderas, agrícolas y de transporte significó un despunte de la actividad económica y uno de los canales del desarrollo de la región. El propósito del artículo es perfilar qué tipo de cooperativismo se articuló en el Distrito Norte de la península de Baja California y qué tipo de relación guardó con el movimiento cooperativista nacional entre 1930 y 1950

Composition of bottom sediments from the Gulf of California

Abundances of globules, micronodules and their aggregates composed of iron sulfides from bottom sediments of the Gulf of California have been determined together with studies of chemical composition of these sediments.

High resolution paleoceanography of the Guaymas Basin, Gulf of California, during the past 15000 yeras

Deep Sea Drilling Project Site 480 (27°54.10'N, 111°39.34'W; 655 m water depth) contains a high resolution record of paleoceanographic change of the past 15000 years for the Guaymas Basin, a region of very high diatom productivity within the central Gulf of California. Analyses of diatoms and silicoflagellates were completed on samples spaced every 40-50 yr, whereas ICP-AES geochemical analyses were completed on alternate samples (sample spacing 80-100 yr). The Bolling-Allerod interval (14.6-12.9 ka) (note, ka refers to 1000 calendar years BP throughout this report) is characterized by an increase in biogenic silica and a decline in calcium carbonate relative to surrounding intervals, suggesting conditions somewhat similar to those of today. The Younger Dryas event (12.9-11.6 ka) is marked by a major drop in biogenic silica and an increase in calcium carbonate. Increasing relative percentage contributions of Azpeitia nodulifera and Dictyocha perlaevis (a tropical diatom and silicoflagellate, respectively) and reduced numbers of the silicoflagellate Octactis pulchra are supportive of reduced upwelling of nutrient-rich waters. Between 10.6 and 10.0 ka, calcium carbonate and A. nodulifera abruptly decline at DSDP 480, while Roperia tesselata, a diatom indicative of winter upwelling in the modern-day Gulf, increases sharply in numbers. A nearly coincident increase in the silicoflagellate Dictyocha stapedia suggests that waters above DSDP 480 were more similar to the cooler and slightly more saline waters of the northern Gulf during much of the early and middle parts of the Holocene (~10 to 3.2 ka). At about 6.2 ka a stepwise increase in biogenic silica and the reappearance of the tropical diatom A. nodulifera marks a major change in oceanographic conditions in the Gulf. A winter shift to more northwesterly winds may have occurred at this time along with the onset of periodic northward excursions (El Nino-driven?) of the North Equatorial Countercurrent during the summer. Beginning between 2.8 and 2.4 ka, the amplitude of biogenic silica and wt% Fe, Al, and Ti (proxies of terrigenous input) increase, possibly reflecting intensification of ENSO cycles and the establishment of modern oceanographic conditions in the Gulf. Increased numbers of O. pulchra after 2.8 ka suggest enhanced spring upwelling.

The California current predator diet database: synthesis of common forage species

Characterization of the diets of upper-trophic predators is a key ingredient in management including the development of ecosystem-based fishery management plans, conservation efforts for top predators, and ecological and economic modeling of predator prey interactions. The California Current Predator Diet Database (CCPDD) synthesizes data from published records of predator food habits over the past century. The database includes diet information for 100+ upper-trophic level predator species, based on over 200 published citations from the California Current region of the Pacific Ocean, ranging from Baja, Mexico to Vancouver Island, Canada. We include diet data for all predators that consume forage species: seabirds, cetaceans, pinnipeds, bony and cartilaginous fishes, and a predatory invertebrate; data represent seven discrete geographic regions within the CCS (Canada, WA, OR, CA-n, CA-c, CA-s, Mexico). The database is organized around predator-prey links that represent an occurrence of a predator eating a prey or group of prey items. Here we present synthesized data for the occurrence of 32 forage species (see Table 2 in the affiliated paper) in the diet of pelagic predators (currently submitted to Ecological Informatics). Future versions of the shared-data will include diet information for all prey items consumed, not just the forage species of interest.