23 research outputs found

    The Making of a Productivity Hotspot in the Coastal Ocean

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    Highly productive hotspots in the ocean often occur where complex physical forcing mechanisms lead to aggregation of primary and secondary producers. Understanding how hotspots persist, however, requires combining knowledge of the spatio-temporal linkages between geomorphology, physical forcing, and biological responses with the physiological requirements and movement of top predators.) off the Baja California peninsula, Mexico.We have identified the set of conditions that lead to a persistent top predator hotspot, which increases our understanding of how highly migratory species exploit productive regions of the ocean. These results will aid in the development of spatially and environmentally explicit management strategies for marine species of conservation concern

    From Sea to Sea: Canada's Three Oceans of Biodiversity

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    Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage

    Respuesta del ecosistema pelågico a la variabilidad interanual del océano frente a Baja California

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    Seasonal anomalies of salinity, phytoplankton chlorophyll a, and zooplankton volume off Baja California were examined from data obtained during 2001–2007. The analyses helped to identify a strong effect of physical processes on the pelagic ecosystem, diminishing near surface salinity and water column integrated phytoplankton biomass, and enhancing zooplankton volume. These changes are associated with an increase of the Pacific Decadal Oscillation (PDO) index, characterizing a warm phase of the index from summer 2002 to at least summer 2006. Negative chlorophyll a anomalies appear to respond to zooplankton grazing activity, with a possible top down effect during this period. Empirical orthogonal functions (EOFs) of Ekman drift reveal the seasonal and interannual patterns that describe the influence of upwelling zones, and there was a strong response to changes in the equatorward wind forcing from 2002 to 2006. The relationship between negative salinity anomalies and the two temporal EOF modes of Ekman drift was evident as a result of relaxation of coastal upwelling during this period. After 2006, the PDO index showed more neutral or negative values, defining the beginning of a cool phase, with positive nearsurface salinity anomalies off Baja California.

    State of the California Current, Spring 2008-2009: cold conditions drive regional differences in coastal production

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    This report describes the state of the California Surrent system (CCS) between the springs of 2008 and 2009 based on observations taken along the west coast of North America. the dominant forcing on the CCS during this time period were La Nina type conditions that prevailed from the summer of 2007 through early 2009, transitioning to neutral El Nino-Southern Oscillation conditions in the spring of 2009. The Pacific Decadal Oscillation index was negative during this time period and its values had not returned to normal by the spring of 2009. The general effects on the California Current system were stronger than normal southward winds and upselling as well as generally colder that normal SST and shallow nitraclines; however, there were regional differences. Off Baja California sea surface temperatures did not respond to the La Nina conditions; however, concentrations of chorophyll a (Chl a) were significantly above normal, probably due to the anomolously high upwelling off Baja during most of the year. Off southern California there was no clear evidence of increased promary or secondary production, despite observations that previous La Nina conditions affected mixed layer depth, temperatures, nutrients, and nitracline depths. In both central and northern California and Oregon, stronger than normal upwelling increased primary production and prevented potential spawning of sardine north of San Francisco. In central California the midwater fish community resembled that of recent cool years, and cover by kelp was much reduced along the coast. Off Oregon there was evidence of increased abundance of boreal copepods, although the neritic boreal species did not appear to extend as far south as central California. Current predictions are for cooler conditions to change to El Nino conditions by the end of 2009; these are expected to last through the Northern Hemisphere winter of 2009-10

    State of the California Current 2010-2011: Regionally Variable Responses to a Strong (But Fleeting?) La Niña

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    State of the California Current CalCOFI Rep., Vol. 52, 2011The state of the California current system (CCS) since spring 2010 has evolved in response to the development of cooler la Niña following the dissipation of the relatively weak and short-lived El Niño event of 2009–2010. The 2009–2010 El Niño appears to have dissipated quite rapidly in early spring 2010, yet the transition to anomalously cool conditions followed somewhat later with the onset of anomalously strong upwelling throughout the CCS in summer 2010 and the development of unusually—in some cases record—cool conditions throughout the CCS. However, following the fairly consistent emergence of cooler la Niña conditions across the CCS going into summer 2010, regional contrasts were apparent. Off southern california, the effects of both the 2009–2010 El Niño and subsequent return to la Niña conditions appear to have had modest effects on the system, and the patterns that attract interest appear to be unfolding over longer time scales (e.g., freshening of upper water column and trends in nitrate and oxygen concentrations). In contrast, the northern california current has exhibited much more dramatic short-term changes over the past two years, due in part to greater variability in environmental forcing affecting this region. Ecosystem responses also varied across the CCS.the pelagic ecosystem off central and southern california showed evidence of enhanced productivity,in terms of rockfish recruitment, seabird abundance and reproductive success, etc., and the planktonic assemblage off Baja california indicated a resurgence of crustacean zooplankton following a period dominated by gelatinous zooplankton. Off northern california and oregon, however, the return to la Niña conditions did not entirely reverse changes in the copepod assemblage arising during the 2009–2010 El Niño, which may have contributed to low at-sea survival of juvenile salmon.At the time of writing, tropical conditions are ENso-neutral and forecast to remain so into fall 2011 and possibly into early 2012, yet the Pdo remained strongly negative into summer 2011. It is uncertain whether the return to cool conditions observed in the past year will continue to govern the state of the california current
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