146 research outputs found
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State of the California current 2012-13: No such thing as an âaverageâ year
This report reviews the state of the California Current System (CCS) between winter 2012 and spring 2013, and includes observations from Washington State to Baja California. During 2012, large-scale climate modes indicated the CCS remained in a cool, productive phase present since 2007. The upwelling season was delayed north of 42°N, but regions to the south, especially 33° to 36°N, experienced average to above average upwelling that persisted throughout the summer. Contrary to the indication of high production suggested by the climate indices, chlorophyll observed from surveys and remote sensing was below average along much of the coast. As well, some members of the forage assemblages along the coast experienced low abundances in 2012 surveys. Specifically, the concentrations of all lifestages observed directly or from egg densities of Pacific sardine, Sardinops sagax, and northern anchovy, Engraulis mordax, were less than previous yearsâ survey estimates. However, 2013 surveys and observations indicate an increase in abundance of northern anchovy. During winter 2011/2012, the increased presence of northern copepod species off northern California was consistent with stronger southward transport. Krill and small-fraction zooplankton abundances, where examined, were generally above average. North of 42°N, salps returned to typical abundances in 2012 after greater observed concentrations in 2010 and 2011. In contrast, salp abundance off central and southern California increased after a period of southward transport during winter 2011/2012. Reproductive success of piscivorous Brandtâs cormorant, Phalacrocorax penicillatus, was reduced while planktivorous Cassinâs auklet, Ptychoramphus aleuticus was elevated. Differences between the productivity of these two seabirds may be related to the available forage assemblage observed in the surveys. California sea lion pups from San Miguel Island were undernourished resulting in a pup mortality event perhaps in response to changes in forage availability. Limited biological data were available for spring 2013, but strong winter upwelling coastwide indicated an early spring transition, with the strong upwelling persisting into early summer
Questioning the rise of gelatinous zooplankton in the World's oceans
During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by ânuisanceâ jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historicalcontext to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference forchanges in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms
The Making of a Productivity Hotspot in the Coastal Ocean
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
Shifts between gelatinous and crustacean plankton in a coastal upwellin region
proyectos RADIALES (IEO) y EURO-BASIN (Ref. 264933, 7FP)Variability in the dominance of copepods vs. gelatinous plankton was analysed using monthly time-series covering the last 55 years and
related to changes in climatic, oceanographic, and fishery conditions in the upwelling region of Galicia (NW Spain). Seasonality was
generally the main component of variability in all groups, both along the coast and in the nearby ocean, but no common long-term
trend was found. Coastal copepods increased since the early 1990s, and gelatinous plankton increased in the ocean during the 1980s.
Different trends were found for gelatinous plankton in two coastal sites, characterized by increases in either medusae or tunicates. In
all series, multiyear periods of relative dominance of gelatinous vs. copepod plankton were evident. In general, copepod periods were
observed in positive phases of the main modes of regional climatic variability. Conversely, gelatinous periods occurred during negative
climatic phases. However, the low correlations between gelatinous plankton and climatic, oceanographic, or fishery variables suggest
that local factors play a major role in their proliferations.7FP, IEOPreprin
Salp contributions to vertical carbon flux in the Sargasso Sea
We developed a one-dimensional model to estimate salp contributions to vertical carbon flux at the Bermuda Atlantic Time-series Study (BATS) site in the North Atlantic subtropical gyre for a 17-yr period (April 1994 to December 2011). We based the model parameters on published rates of salp physiology and experimentally determined sinking and decomposition rates of salp carcasses. Salp grazing was low during non-bloom conditions, but routinely exceeded 100% of chlorophyll standing stock and primary production during blooms. Fecal pellet production was the largest source of salp carbon flux (78% of total), followed by respiration below 200 m (19%), sinking of carcasses (3%), and DOC excretion below 200 m (\u3c 0.1%). Thalia democratica, Salpa fusiformis, Salpa aspera, Wheelia cylindrica, and Iasis zonaria were the five highest contributors, accounting for 95% of total salp-mediated carbon flux. Seasonally, salp flux was higher during spring-summer than fall-winter, due to seasonal changes in species composition and abundance. Salp carbon export to 200 m was on average 2.3 mg C m(-2) d(-1) across the entire time series. This is equivalent to 11% of the mean 200 m POC flux measured by sediment traps in the region. During years with significant salp blooms, however, annually-averaged salp carbon export was the equivalent of up to 60% of trap POC flux at 200 m. Salp carbon flux attenuated slowly, and at 3200 m the average modeled carbon from salps was 109% of the POC flux measured in sediment traps at that depth. Migratory and carcass carbon export pathways should also be considered (alongside fecal pellet flux) as facilitating carbon export to sequestration depths in future studies. Published by Elsevier Ltd
Calcareous phytoplankton response to the half century of interannual climatic variability in Santa Barbara Basin (California)
A high-resolution study of calcareous phytoplankton in a box core from the Santa Barbara Basin (SBB) reveals floral assemblage fluctuations which can be related to climatic and paleoceanographic changes during the last half century (1940-1996). In particular, Gephyrocapsa oceanica production increased during El NiĂąo periods, in response to high temperatures, silica depletion, and increased iron availability. Conversely, Helicosphaera carteri flux increases in conjunction with lower surface temperatures associated with La NiĂąa episodes. Increasing abundances of Florisphaera profunda and Umbilicosphaera sibogae after 1970 reflect a warming trend and increased stratification within the basin associated with the warm phase of the Pacific Decadal Oscillation (PDO). Conversely, increased abundances of Coccolithus pelagicus and Calcidiscus leptoporus before 1970 mark the cold phase of PDO. These coccolithophore production rate data are consistent with instrumental records of surface and thermocline temperatures monitored since 1950. This is the first study to document the response of calcareous phytoplankton to surface water warming occurring in SBB since 197
From Sea to Sea: Canada's Three Oceans of Biodiversity
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
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The state of California current, 2001 â 2002 : will the Californa current system keep its cool, or is El NiĂąo coming?
This report summarizes physical and biological conditions in the California Current System (CCS), from Oregon to Baja California, in 2001 and 2002. The principal sources of the observations described here are the CalCOFI (California Cooperative Oceanic Fisheries Investigations), IMECOCAL (Investigaciones Mexicanas de la Corriente de California), and U.S. GLOBECLTOP (Global Ecosystems Long-term Observation Program) programs. Large-scale atmospheric and oceanic conditions in the Pacific point to a fourth consecutive La NiĂąa-like year. This has contributed to generally stronger than normal upwelling and uncharacteristically cool waters in much of the CCS, a pattern that has persisted since late 1998. Biological productivity has been generally higher as well, particularly off Oregon. Within the observed interannual fluctuations of recent years, these conditions suggest a generally elevated production off California and Oregon, but cool conditions have led to lower than normal zooplankton biomass off Baja California. Although the tropical Pacific has exhibited some indications of a developing El NiĂąo, it is not likely to impact the CCS during the productive upwelling season of 2002. These observations are continuing evidence that a regime shift may have occurred in 1998, resulting in substantial change in ecosystem structure in the CCS. Continued monitoring and analysis of the state of the CCS in this context is needed. We outline a plan for an integrated monitoring program for the entire region, through the creation of ACCEO (Alliance for California Current Ecosystem Observation)
Recommended from our members
State of the California Current 2012â13: No Such Thing as an "Average" Year
This report reviews the state of the California Current System (CCS) between winter 2012 and spring 2013, and includes observations from Washington State to Baja California. During 2012, large-scale climate modes indicated the CCS remained in a cool, productive phase present since 2007. The upwelling season was delayed north of 42ËN, but regions to the south, especially 33Ë to 36ËN, experienced average to above average upwelling that persisted throughout the summer. Contrary to the indication of high production suggested by the climate indices, chlorophyll observed from surveys
and remote sensing was below average along much of
the coast. As well, some members of the forage assemblages
along the coast experienced low abundances in
2012 surveys. Specifically, the concentrations of all lifestages
observed directly or from egg densities of Pacific
sardine, Sardinops sagax, and northern anchovy, Engraulis
mordax, were less than previous yearsâ survey estimates.
However, 2013 surveys and observations indicate an
increase in abundance of northern anchovy. During winter
2011/2012, the increased presence of northern copepod
species off northern California was consistent with
stronger southward transport. Krill and small-fraction
zooplankton abundances, where examined, were generally
above average. North of 42ËN, salps returned to
typical abundances in 2012 after greater observed concentrations
in 2010 and 2011. In contrast, salp abundance
off central and southern California increased after a
period of southward transport during winter 2011/2012.
Reproductive success of piscivorous Brandtâs cormorant,
Phalacrocorax penicillatus, was reduced while planktivorous
Cassinâs auklet, Ptychoramphus aleuticus was elevated.
Differences between the productivity of these two seabirds
may be related to the available forage assemblage observed in the surveys. California sea lion pups from
San Miguel Island were undernourished resulting in a
pup mortality event perhaps in response to changes in
forage availability. Limited biological data were available
for spring 2013, but strong winter upwelling coastwide
indicated an early spring transition, with the strong
upwelling persisting into early summer
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