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The energetic content of primary and secondary consumers is central to understanding ecosystem functioning, community assembly, and trophodynamics. However, these foundational data are often limited, especially for marine ecosystems. Here we report the energy densities of important prey species in the California Current Ecosystem. We investigated variation in energy density within and between species and explored potential underlying causes of these differences. Northern anchovy (Engraulis mordax) is the most energy dense of the species analyzed with a median value nearly twice as high as was found in krill (Euphausia pacifica and Thysanoessa spinifera). Relationships with body size varied among species; krill energy density increased, with both length and wet weight. In addition, we find that anchovy, sardine (Sardinops sagax), and market squid (Doryteuthis opalescens) have higher energy content in the summer and fall as compared to the spring. This aligns with the ecosystem phenology of strong upwelling during spring (March - May) driving high primary productivity, followed by widespread predator presence through the summer and fall (June - October). Our results inform food web studies in the California Current and suggest new avenues for investigating differences in species and ecosystem energetics in an era of rapid global change. [ABSTRACT FROM AUTHOR]

Evidence indicates that members of the marine bird research and management communities should view seabirds from the seabirds' perspective, as marine organisms, rather than the pervading view derived from human's interaction with the sea, i.e., as temporary visitors centered on home ports. By doing so, research results and management plans will be more realistic and effective. Seabirds themselves only temporarily visit land in their reproductive attempts, with most of their time otherwise spent at sea, as much as 90% in the lifetimes of some species. This is especially true among seabirds of the more productive stretches of water, such as eastern boundary currents, which as a rule have relatively few islands on which to nest as well as these waters typically being dominated by seasonal, non-breeding species. A case in point is the Pigeon Guillemot Cepphus columba of the California Current, a species/population that dwells in waters of the Pacific Northwest for most of the year, except for a quick migration south, then back north, for nesting. It ventures south to then have to compete with far more abundant species. The point is that protecting just seabird nesting islands, but ignoring marine issues within the whole of respective annual ranges, is often not a successful strategy, as exemplified to the extreme by the trend toward extinction of African Penguin Spheniscus demersus of the Benguela Current, where seabird species visitors are far more abundant. [ABSTRACT FROM AUTHOR]

The effects of climate warming on ecosystem dynamics are widespread throughout the world's oceans. In the Northeast Pacific, large‐scale climate patterns such as the El Niño/Southern Oscillation and Pacific Decadal Oscillation, and recently unprecedented warm ocean conditions from 2014 to 2016, referred to as a marine heatwave (MHW), resulted in large‐scale ecosystem changes. Larval fishes quickly respond to environmental variability and are sensitive indicators of ecosystem change. Categorizing ichthyoplankton dynamics across marine ecosystem in the Northeast Pacific can help elucidate the magnitude of assemblage shifts, and whether responses are synchronous or alternatively governed by local responses to regional oceanographic conditions. We analyzed time‐series data of ichthyoplankton abundances from four ecoregions in the Northeast Pacific ranging from subarctic to subtropical: the Gulf of Alaska (1981–2017), British Columbia (2001–2017), Oregon (1998–2017), and the southern California Current (1981–2017). We assessed the impact of the recent (2014–2016) MHW and how ichthyoplankton assemblages responded to past major climate perturbations since 1981 in these ecosystems. Our results indicate that the MHW caused widespread changes in the ichthyoplankton fauna along the coast of the Northeast Pacific Ocean, but impacts differed between marine ecosystems. For example, abundances for most dominant taxa were at all‐time lows since the beginning of sampling in the Gulf of Alaska and British Columbia, while in Oregon and the southern California Current species richness increased as did abundances of species associated with warmer waters. Lastly, species associated with cold waters also increased in abundances close to shore in southern California during the MHW, a pattern that was distinctly different from previous El Niño events. We also found several large‐scale, synchronized ichthyoplankton assemblage composition shifts during past major climate events. Current climate projections suggest that MHWs will become more intense and thus our findings can help project future changes in larval dynamics, allowing for improved ecosystem management decisions. [ABSTRACT FROM AUTHOR]

Coastal winds in the California Current System (CCS) are credited with the high productivity of its planktonic ecosystem and the shallow hypoxic and corrosive waters that structure diverse macrofaunal habitats. These winds thus are considered a leading mediator of climate change impacts in the CCS and other Eastern Boundary Upwelling systems. We use an eddy‐permitting regional model to downscale the response of the CCS to three of the major distinct climate changes commonly projected by global Earth System Models: regional winds, ocean warming and stratification, and remote water chemical properties. An increase in alongshore winds intensifies spring upwelling across the CCS, but this response is muted by increased stratification, especially during summer. Despite the seasonal shift in regional wind‐driven upwelling, basin‐scale changes are the decisive factor in the response of marine ecosystem properties including temperature, nutrients, productivity, and oxygen. Downscaled temperature increases and dissolved oxygen decreases are broadly consistent with coarse resolution Earth System Models, and these projected changes are large and well constrained across the models, whereas nutrient and productivity changes are small compared to the intermodel spread. These results imply that global models with poor resolution of coastal processes nevertheless yield important information about the dominant climate impacts on coastal ecosystems. Key Points: We dynamically downscale the response of the California Current System to climate changes from five global Earth System ModelsStratification and remote chemical properties, rather than regional winds, play a decisive role in coastal biogeochemistry changesOxygen decreases and temperature increases are robust across downscaled models, but the nutrient and productivity changes are not [ABSTRACT FROM AUTHOR]

A three‐dimensional physical‐biological model was used to study the dynamics of physical and biological processes in the central California Current System (CCS) from 1993 to 2016 and investigate its response to different climate modes. The variations of new production (NP) and nitrate fluxes in the central CCS showed robust seasonal and interannual variability. In the coastal upwelling region (0–150 km offshore), the variability of NP was associated with both coastal upwelling and alongshore nitrate advection. In the coastal transition zone (150–300 km offshore), it was related to nitrate fluxes that were determined primarily by the physics rather than nitrate concentration, with vertical mixing and offshore transport being dominant factors. In the offshore oceanic region (California Current; 300–1,000 km offshore), nitrate concentrations played a more important role in the variations of nitrate fluxes, and the NP variability was dominated by the nutrient supplies of vertical mixing and lateral transports. Although El Niño–Southern Oscillation can affect coastal upwelling, alongshore currents, and nitrate fluxes, the coastal NP responded to El Niño–Southern Oscillation mostly in the frequencies of <1 and >6 years. Pacific Decadal Oscillation and North Pacific Gyre Oscillation may affect the CCS ecosystem through large‐scale winds and stratification, modifying the circulation in the upper layer and leading to changes in nitrate concentration and NP. Plain Language Summary The central California Current System (CCS) is one of the most productive ecosystems in the global ocean, because strong coastal upwelling brings a large amount of subsurface nutrients to the sunlit layer and supports abundant phytoplankton growth. Understanding the response of this system to varying physical forcing is of great importance in predicting how marine ecosystem will evolve with global change. By using a three‐dimensional model, this study demonstrates that biological properties in the central CCS show strong interannual variability. The dominant driver leading to this variability varies in different subregions moving from the coast to offshore. Over the CCS, climate variability can cause variations in surface wind, stratification, sea level, and circulations at different time scales, which contribute to changes in nutrient supply and phytoplankton production. [ABSTRACT FROM AUTHOR]

Highlights • Models challenged to simulate full range of global ocean chlorophyll concentrations. • Two-phytoplankton size class model captures regional meso- to oligotrophic transition. • Adding coastal diatom enables simulation of high chlorophyll in coastal upwelling. • High chlorophyll arises from weaker top-down control and transient trophic decoupling. • New model improves simulated distribution of coastal hypoxia. Abstract The measured concentration of chlorophyll a in the surface ocean spans four orders of magnitude, from ∼0.01 mg m−3 in the oligotrophic gyres to >10 mg m−3 in coastal zones. Productive regions encompass only a small fraction of the global ocean area yet they contribute disproportionately to marine resources and biogeochemical processes, such as fish catch and coastal hypoxia. These regions and/or the full observed range of chlorophyll concentration, however, are often poorly represented in global earth system models (ESMs) used to project climate change impacts on marine ecosystems. Furthermore, recent high resolution (∼10 km) global earth system simulations suggest that this shortfall is not solely due to coarse resolution (∼100 km) of most global ESMs. By integrating a global biogeochemical model that includes two phytoplankton size classes (typical of many ESMs) into a regional simulation of the California Current System (CCS) we test the hypothesis that a combination of higher spatial resolution and enhanced resolution of phytoplankton size classes and grazer linkages may enable global ESMs to better capture the full range of observed chlorophyll. The CCS is notable for encompassing both oligotrophic (<0.1 mg m−3) and productive (>10 mg m−3) endpoints of the global chlorophyll distribution. As was the case for global high-resolution simulations, the regional high-resolution implementation with two size classes fails to capture the productive endpoint. The addition of a third phytoplankton size class representing a chain-forming coastal diatom enables such models to capture the full range of chlorophyll concentration along a nutrient supply gradient, from highly productive coastal upwelling systems to oligotrophic gyres. Weaker 'top-down' control on coastal diatoms results in stronger trophic decoupling and increased phytoplankton biomass, following the introduction of new nutrients to the photic zone. The enhanced representation of near-shore chlorophyll maxima allows the model to better capture coastal hypoxia along the continental shelf of the North American west coast and may improve the representation of living marine resources. [ABSTRACT FROM AUTHOR]

Coastal upwelling is responsible for thriving marine ecosystems and fisheries that are disproportionately productive relative to their surface area, particularly in the world's major eastern boundary upwelling systems. Along oceanic eastern boundaries, equatorward wind stress and the Earth's rotation combine to drive a near‐surface layer of water offshore, a process called Ekman transport. Similarly, positive wind stress curl drives divergence in the surface Ekman layer and consequently upwelling from below, a process known as Ekman suction. In both cases, displaced water is replaced by upwelling of relatively nutrient‐rich water from below, which stimulates the growth of microscopic phytoplankton that form the base of the marine food web. Ekman theory is foundational and underlies the calculation of upwelling indices such as the "Bakun Index" that are ubiquitous in eastern boundary upwelling system studies. While generally valuable first‐order descriptions, these indices and their underlying theory provide an incomplete picture of coastal upwelling. Here we review the relevant dynamics and limitations of classical upwelling indices, particularly related to representation of the surface wind stress, the influence of geostrophic currents, and the properties of upwelled water. To address these shortcomings, we present two new upwelling indices for the U.S. West Coast (31–47°N), which are available from 1988 to present. The Coastal Upwelling Transport Index and the Biologically Effective Upwelling Transport Index provide improved estimates of vertical transport and vertical nitrate flux, respectively, by leveraging technological and scientific advances realized since the introduction of the Bakun Index nearly a half century ago. Plain Language Summary: The California Current System, running along the North American West Coast, hosts a rich and diverse marine ecosystem that provides considerable socioeconomic benefit. The process underlying this exceptional biological productivity is wind‐driven coastal upwelling, which delivers deep, nutrient‐rich water to the sunlit surface layer and stimulates growth of phytoplankton that form the base of the marine food web. Given the ecological importance of upwelling, indices designed to monitor its intensity (e.g., the "Bakun Index") were introduced nearly 50 years ago. While these indices have proved extremely useful, they have a number of limitations as they are derived from relatively coarse resolution atmospheric pressure fields. In particular, uncertainties arise in the estimation of wind stress and from the omission of the influence of ocean circulation. Furthermore, historical indices estimate only the amount of water upwelled, not the nutrient content of that water. Here we present new indices that leverage ocean models, satellite data, and in situ observations to more accurately estimate upwelling strength as well as the amount of nitrate being upwelled. The new indices are publicly available, extend from 1988 to present, and will be valuable for monitoring upwelling in near real time and for understanding its impacts on the marine ecosystem. Key Points: New upwelling indices are presented for the U.S. West Coast (31–47°N) to address shortcomings in historical indicesThe Coastal Upwelling Transport Index (CUTI) estimates vertical volume transport (i.e., upwelling/downwelling)The Biologically Effective Upwelling Transport Index (BEUTI) estimates vertical nitrate flux [ABSTRACT FROM AUTHOR]

The ocean salmon fishery on the US West Coast has faced periodic closures of varying extents in order to protect vulnerable runs. These closures can have serious consequences for fishers and fishing communities, and have necessitated the release of millions of dollars of federal disaster aid. The 2017 ocean Chinook troll fishery (the major salmon ocean fishery) is closed between southern Oregon and northern California to protect the Klamath River fall Chinook, which is forecast to return in low numbers. A model of vessel fishing choices was used in combination with an established input-output model to estimate the potential economic impact of this closure on fishers and fishing communities. The analysis predicts that this closure of the ocean fishery will result in a loss of $5.8–$8.9 million in income, $12.8–$19.6 million in sales, and 200–330 jobs. These estimates are only a partial estimate of the economic impacts of the 2017 salmon regulations, as they do not fully account for the effects of the limited season outside of the closed ocean area or the effects on other salmon fisheries (e.g. the gillnet and recreational fisheries). The impacts are not distributed evenly in space, with the largest relative losses occurring in the Coos Bay, Brookings, and Eureka regions. This information may be useful as policymakers consider mitigating economic losses in the fishery and associated communities. Early estimates of economic impacts of fishery closures may also enable quicker determination of the need and extent of disaster assistance and a more timely response. [ABSTRACT FROM AUTHOR]

Abstract: In marine ecosystems, many planktonic organisms precipitate biogenic silica (bSiO2) to build silicified skeletons. Among them, giant siliceous rhizarians (>500 μm), including Radiolaria and Phaeodaria, are important contributors to oceanic carbon pools but little is known about their contribution to the marine silica cycle. We report the first analyses of giant phaeodarians to bSiO2 export in the California Current Ecosystem. We measured the silica content of single rhizarian cells ranging in size from 470 to 3,920 μm and developed allometric equations to predict silica content (0.37–43.42 μg Si/cell) from morphometric measurements. Using sediment traps to measure phaeodarian fluxes from the euphotic zone on four cruises, we calculated bSiO2 export produced by two families, the Aulosphaeridae and Castanellidae. Biogenic silica export ranged from <0.01 to 0.63 mmol Si · m−2 · day−1. These two families alone contributed on average 10% (range 0–80%) of total bSiO2 export from the euphotic zone. Their proportional contributions increased substantially in more oligotrophic regions with lower bSiO2 fluxes. Using the in situ Underwater Vision Profiler 5, we characterized vertical distributions of the giant phaeodarian family Aulosphaeridae to a depth of 500 m and inferred their contribution to bSiO2 export in deeper waters. We found a significant increase of Aulosphaeridae export (<0.01 to 2.82 mmol Si · m−2 · day−1) when extended to mesopelagic depths. Using a global data set of in situ profiles, we estimated the significance of Aulosphaeridae to bSiO2 export and revealed that they can act as major exporters of bSiO2 to the mesopelagic zone in various regions. [ABSTRACT FROM AUTHOR]

As anthropogenic changes interact with natural climate cycles, the variability of marine ecosystems is likely to increase. Changes in productivity of particular fisheries might be expected to lead not only to direct impacts within a fishery but to economic and ecological effects on other fisheries if there is substantial cross-participation by fishers. We use data from the US West Coast salmon troll fishery before, during, and after a large-scale closure to illustrate how altered resource availability influences the behaviour of fishing vessels in heterogeneous ways. We find that vessels were less likely to participate in fishing of any type during the closure, with >40% of vessels ceasing fishing temporarily and 17% exiting permanently. Vessels that were more dependent on salmon were more likely to cease fishing while more diversified vessels were more likely to continue. In spite of a high level of cross-participation, we find limited evidence that vessels increased their participation in other fisheries to offset lost salmon revenue. Ports that obtained more of their revenue from salmon troll vessels saw larger decreases in their revenue during the closure. Ocean conditions from 2013 to 2015 suggest the possibility of another highly restricted salmon fishing season in 2017. Our models predict that such restrictions would cause another economic disaster and lead to a large fraction of vessels exiting fishing but suggest that effects on fisheries linked by cross-participation are likely to be low. [ABSTRACT FROM AUTHOR]

Intraspecific variability is increasingly recognized as an important component of foraging behavior that can have implications for both population and community dynamics. We used an individual-level approach to describe the foraging behavior of an abundant, generalist predator that inhabits a dynamic marine ecosystem, focusing specifically on the different foraging strategies used by individuals in the same demographic group. We collected data on movements and diving behavior of adult female California sea lions ( Zalophus californianus) across multiple foraging trips to sea. Sea lions ( n = 35) used one of three foraging strategies that primarily differed in their oceanic zone and dive depth: a shallow, epipelagic strategy, a mixed epipelagic/benthic strategy, and a deep-diving strategy. Individuals varied in their degree of fidelity to a given strategy, with 66 % of sea lions using only one strategy on all or most of their foraging trips across the two-month tracking period. All foraging strategies were present in each of the sampling years, but there were inter-annual differences in the population-level importance of each strategy that may reflect changes in prey availability. Deep-diving sea lions traveled shorter distances and spent a greater proportion of time at the rookery than sea lions using the other two strategies, which may have energetic and reproductive implications. These results highlight the importance of an individual-based approach in describing the foraging behavior of female California sea lions and understanding how they respond to the seasonal and annual changes in prey availability that characterize the California Current System. [ABSTRACT FROM AUTHOR]

The complexity of ecosystem-based management (EBM) of natural resources has given rise to research frameworks such as integrated ecosystem assessments (IEA) that pull together large amounts of diverse information from physical, ecological, and social domains. Conceptual models are valuable tools for assimilating and simplifying this information to convey our understanding of ecosystem structure and functioning. Qualitative network models (QNMs) may allow us to conduct dynamic simulations of conceptual models to explore natural–social relationships, compare management strategies, and identify tradeoffs. We used previously developed QNM methods to perform simulations based on conceptual models of the California Current ecosystem's pelagic communities and related human activities and values. Assumptions about community structure and trophic interactions influenced the outcomes of the QNMs. In simulations where we applied unfavorable environmental conditions for production of salmon (Oncorhynchusspp.), intensive management actions only modestly mitigated declines experienced by salmon, but strongly constrained human activities. Moreover, the management actions had little effect on a human wellbeing attribute, sense of place. Sense of place was most strongly affected by a relatively small subset of all possible pair-wise interactions, although the relative influence of individual pair-wise interactions on sense of place grew more uniform as management actions were added, making it more difficult to trace effective management actions via specific mechanistic pathways. Future work will explore the importance of changing conceptual models and QNMs to represent management questions at finer spatial and temporal scales, and also examine finer representation of key ecological and social components. [ABSTRACT FROM PUBLISHER]

The ability to assess, model, predict and manage the impacts of climate change and other anthropogenic stressors on marine ecosystems depends on having adequate ecological time series. Unfortunately the development of ecological time series considerably lags those for the physics and chemistry of the oceans. Ichthyoplankton time series are proposed here to fill this gap in ocean observations. Marine fish species spanning a wide range of families, habitats, feeding guilds, and trophic levels broadcast large numbers of their reproductive products into the open waters. For a limited period, the larvae generally reside in the upper 200 m of the water column, where they may be quantitatively sampled with plankton nets. Larval abundance provides a relative index for adult spawning stock biomass, enabling diverse fish communities to be monitored quantitatively by relatively simple means. Recent analyses of the ichthyoplankton time series extending back to 1951 from the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program indicate that non-commercial as well as commercially-exploited taxa have experienced dramatic change in recent decades. The CalCOFI data set is re-sampled here to show that a reduced sampling program—one based on a few stations along a single transect (cf >50 stations along 6 transects for CalCOFI) or one based on a shorter time series—can, within limits, obtain similar single-species and multivariate patterns of abundance. Ichthyoplankton survey programs may thus provide the basis for a global system of ocean ecological observations in addition to their primary use today for fisheries stock assessment. [ABSTRACT FROM AUTHOR]

The common ocean sunfish, Mola mola , occupies a unique position in the eastern Pacific Ocean and the California Current Large Marine Ecosystem (CCLME) as the world's heaviest, most fecund bony fish, and one of the most abundant gelativores. M. mola frequently occur as bycatch in fisheries worldwide and comprise the greatest portion of the bycatch in California's large-mesh drift gillnet fishery. In this first long-term tagging study of any ocean sunfish species in the eastern Pacific, 15 M. mola (99 cm to 200 cm total length) were tagged in the southern California Bight (SCB) between 2003 and 2010 using 14 satellite pop-off archival tags (PATs) and one Fastloc Mk10 GPS tag. Ten tags provided positional data for a cumulative dataset of 349 tracking days during the months of July through March. Thirteen tags provided temperature and depth data. All M. mola remained within ~ 300 km of the coast, and nearly all exhibited seasonal movement between the SCB and adjacent waters off northern and central Baja California, Mexico. No tagged individuals were tracked north of the SCB. Tag depth data showed diel vertical migration and occasional deep (> 500 m) dives. Data from the Fastloc GPS tag allowed close examination of the relationship between the movements of the largest tagged ocean sunfish (2 m TL) and fine-scale oceanographic features. Near-instantaneous satellite sea surface temperature images showed this individual associated with upwelling fronts along its migration path, which exceeded 800 km and ranged from 6 to 128 km from the coast. Tag depth data showed active use of the water column within the frontal zones. Synthetic aperture radar (SAR) images demonstrated that surface slicks, which often indicate convergent circulation, coincided with this type of front. Zooplankton tows in the southern region of tracking off central Baja California, Mexico revealed dense populations of salps toward the warm side of these fronts. Satellite tag and ecosystem data suggest that bio-physical interactions in coastal upwelling fronts create favorable foraging habitat. [ABSTRACT FROM AUTHOR]

Ocean conditions can greatly impact lower trophic level prey assemblages in marine ecosystems, with effects of ocean state propagating to higher trophic levels. In many regions throughout their range, common murre ( Uria aalge ) exhibit narrow dietary breadth in feeding chicks and therefore are vulnerable to recruitment failures of dominant prey species during the breeding season. Contrastingly, common murres nesting in the northern California Current off Oregon, exhibit high species diversity and variability in dominant prey consumed. We studied the diets of common murres over 10 years between 1998 and 2011, a period in which the northern California Current experienced dramatic interannual variability in ocean conditions. Likewise, murre diets off Oregon varied considerably. Interannual variation in murre chick diets was influenced by environmental drivers occurring before and during the breeding season, and at both basin and local scales. While clupeids (likely Pacific herring, Clupea pallasii ) were an important diet component throughout the study period, in some years murre diets were dominated by Pacific sand lance ( Ammodytes hexapterus ) and in other years by osmerids (likely whitebait smelt, Allosmerus elongatus and surf smelt, Hypomesus pretiosus ). Years in which the Pacific Decadal Oscillation and local sea surface temperatures were higher during summer also showed elevated levels of clupeids in murre diets, while years with higher North Pacific Gyre Oscillation index values and greater local winter ichthyoplankton biomass had fewer clupeids and more sand lance or smelts. Years with higher values of the Northern Oscillation Index during summer and an earlier spring transition showed higher proportion of smelts in the diets. Nesting phenology and reproductive success were negatively correlated with gradients in sand lance and clupeids, respectively, reflecting demographic consequences of environmental variability mediated through bottom-up food web dynamics. [ABSTRACT FROM AUTHOR]

Numerous monitoring efforts are underway to improve understanding of ocean acidification and its impacts on coastal environments, but there is a need to develop a coordinated approach that facilitates spatial and temporal comparisons of drivers and responses on a regional scale. Toward that goal, the California Current Acidification Network (C-CAN) held a series of workshops to develop a set of core principles for facilitating integration of ocean acidification monitoring efforts on the US West Coast. The recommended core principles include: (1) monitoring measurements should facilitate determination of aragonite saturation state (Ωarag) as the common currency of comparison, allowing a complete description of the inorganic carbon system; (2) maximum uncertainty of ±0.2 in the calculation of Ωarag is required to adequately link changes in ocean chemistry to changes in ecosystem function; (3) inclusion of a variety of monitoring platforms and levels of effort in the network will insure collection of high-frequency temporal data at fixed locations as well as spatial mapping across locations; (4) physical and chemical oceanographic monitoring should be linked with biological monitoring; and (5) the monitoring network should share data and make it accessible to a broad audience. [ABSTRACT FROM AUTHOR]

In 2007, the US west coast shellfish industry began to feel the effects of unprecedented levels of larval mortality in commercial hatcheries producing the Pacific oyster Crassostrea gigas. Subsequently, researchers at Whiskey Creek Shellfish Hatchery, working with academic and government scientists, showed a high correlation between aragonite saturation state (Ωarag) of inflowing seawater and survival of larval groups, clearly linking increased CO2 to hatchery failures. This work led the Pacific Coast Shellfish Growers Association (PCSGA) to instrument shellfish hatcheries and coastal waters, establishing a monitoring network in collaboration with university researchers and the US Integrated Ocean Observing System. Analytical developments, such as the ability to monitor Ωarag in real time, have greatly improved the industry's understanding of carbonate chemistry and its variability and informed the development of commercial-scale water treatment systems. These treatment systems have generally proven effective, resulting in billions of additional oyster larvae supplied to Pacific Northwest oyster growers. However, significant challenges remain, and a multifaceted approach, including selective breeding of oyster stocks, expansion of hatchery capacity, continued monitoring of coastal water chemistry, and improved understanding of biological responses will all be essential to the survival of the US west coast shellfish industry. [ABSTRACT FROM AUTHOR]

Various ocean-climate models driven by increased greenhouse gases and higher temperatures predict a decline in oceanic dissolved oxygen ( DO) as a result of greater stratification, reduced ventilation below the thermocline, and decreased solubility at higher temperatures. Since spreading of low oxygen waters is underway and predicted to increase, understanding impacts on higher trophic levels is essential. Within the California Current System, shoaling of the oxygen minimum zone ( OMZ) is expected to produce complex changes. Onshore movement of the OMZ could lead to habitat compression for species with higher oxygen requirements while allowing expansion of species tolerant of low bottom DO. As part of annual groundfish surveys, we sampled catch across a range of conditions from the upper to the lower limit of the OMZ and shoreward across the continental shelf of the US west coast. DO ranged from 0.02 to 4.25 mL L−1 with 642 stations (of 1020 sampled) experiencing hypoxic conditions in 2008-2010. Catch and species richness exhibited significant and positive relationships with near-bottom oxygen concentration. The probability of occurrence was estimated for four species (spotted ratfish, petrale sole, greenstriped rockfish and Dover sole) using a binomial Generalized Additive Model. The models for each species included terms for position, day of the year, salinity, near-bottom temperature and the interaction term between depth and near-bottom DO. Spotted ratfish and petrale sole were sensitive to changes in near-bottom oxygen, while greenstriped rockfish and Dover sole show no changes in probability of occurrence in relation to changes in oxygen concentration. [ABSTRACT FROM AUTHOR]

Reported trends in the mean and variability of coastal upwelling in eastern boundary currents have raised concerns about the future of these highly productive and biodiverse marine ecosystems. However, the instrumental records on which these estimates are based are insufficiently long to determine whether such trends exceed preindustrial limits. In the California Current, a 576-year reconstruction of climate variables associated with winter upwelling indicates that variability increased over the latter 20th century to levels equaled only twice during the past 600 years. This modern trend in variance may be unique, because it appears to be driven by an unprecedented succession of extreme, downwelling-favorable, winter climate conditions that profoundly reduce productivity for marine predators of commercial and conservation interest. [ABSTRACT FROM AUTHOR]

The marine life of Canada's Pacific marine ecosystems, adjacent to the province of British Columbia, may be relatively responsive to rapid oceanographic and environmental change associated with global climate change due to uniquely evolved plasticities and resiliencies as well as particular sensitivities and vulnerabilities, given this dynamic and highly textured natural setting. These marine ecosystems feature complex interfaces of coastal geomorphology, climate, and oceanography, including a dynamic oceanographic and ecological transition zone formed by the divergence of the North Pacific Current into the Alaskan coastal current and the California Current, and by currents transporting warm tropical waters from the south. Despite long-term warming in the region, sea surface temperatures in Canada's Pacific have been anomalously cool since 2007 with La Niña-type conditions prevailing as we enter a cool phase of the Pacific Decadal Oscillation, possibly masking future warming. When warmer El Niño conditions prevail, many southern species invade, strongly impacting local species and reorganizing biological communities. Acidification and deoxygenation are anomalously high in the region due to the weakening ventilation of subsurface waters resulting from increased stratification. A broad spectrum of biological responses to these changes are expected. Non-climate anthropogenic stressors affect the capacity of biota to adapt to climate changes. It will be challenging to forecast the responses of particular species, and to map climate vulnerabilities accurately enough to help prioritize and guide adaptation planning. It will be more challenging to develop forecasts that account for indirect effects within biological communities and the intricate and apparently non-deterministic behaviours of highly complex and variable marine ecosystems, such as those of Canada's Pacific. We recommend and outline national and regional climate assessments in Canada and adaptation planning and implementation including integrated coastal management and marine spatial planning and management. [ABSTRACT FROM AUTHOR]

Chinook Salmon (Oncorhynchus tshawytscha) is an economically and ecologically important species, and populations from the west coast of North America are a major component of fisheries in the North Pacific Ocean. The anadromous life history strategy of this species generates populations (or stocks) that typically are differentiated from neighboring populations. In many cases, it is desirable to discern the stock of origin of an individual fish or the stock composition of a mixed sample to monitor the stock-specific effects of anthropogenic impacts and alter management strategies accordingly. Genetic stock identification (GSI) provides such discrimination, and we describe here a novel GSI baseline composed of genotypes from more than 8000 individual fish from 69 distinct populations at 96 single nucleotide polymorphism (SNP) loci. The populations included in this baseline represent the likely sources for more than 99% of the salmon encountered in ocean fisheries of California and Oregon. This new genetic baseline permits GSI with the use of rapid and cost-effective SNP genotyping, and power analyses indicate that it provides very accurate identification of important stocks of Chinook Salmon. In an ocean fishery sample, GSI assignments of more than 1000 fish, with our baseline, were highly concordant (98.95%) at the reporting unit level with information from the physical tags recovered from the same fish. This SNP baseline represents an important advance in the technologies available to managers and researchers of this species. [ABSTRACT FROM AUTHOR]

The California Current system is a large marine ecosystem with transition gradients between subarctic and tropical biomes containing diverse habitats. Biogeographic species groups must be carefully analyzed in order to detect tendencies shifting the ecosystem toward a more temperate or tropical state. Species composition of hyperiid amphipods was analyzed in July 2002 for evidence of subarctic water intrusion and for signals of the El Niño event developing in the equatorial Pacific. Multivariate analysis showed a dominance of “transition zone” species typical of the California Current. The main evidence of subarctic water intrusion was the extended distribution of Themisto pacifica, which reached as far south as 27°N, with particularly high abundances at 30–32°N. The intrusion of subarctic water took place despite evidence that an El Niño event was in progress. The zonal advection due to El Niño intersected the equatorward flow of the subarctic intrusion and probably produced a large cyclonic eddy off Baja California. This eddy maintained a limited El Niño influence at a few offshore stations near its southern boundary. The main environmental variables influencing the amphipod assemblage structure were water temperature and the abundance of salps. T. pacifica, a species with cool water affinity, was more sensitive to temperature, whereas subtropical species, such as Vibilia armata, were strongly correlated with the availability of salps. [ABSTRACT FROM AUTHOR]

Highlights: [•] We designed seasonal environmental multivariate indicators (MOCI). [•] MOCI reproduced known temporal variability and key events of anomalous conditions. [•] Subtropical transport decreased, subarctic increased, and upwelling intensified. [•] Seasonal MOCI did not relate to chlorophyll-a concentrations or krill abundance. [•] Seasonal MOCI explained variability in copepod biomass and seabird breeding success. [Copyright &y& Elsevier]

The goal of the Pacific Ocean Boundary Ecosystem and Climate Study (POBEX) was to diagnose the large-scale climate controls on regional transport dynamics and lower trophic marine ecosystem variability in Pacific Ocean boundary systems. An international team of collaborators shared observational and eddy-resolving modeling data sets collected in the Northeast Pacific, including the Gulf of Alaska (GOA) and the California Current System (CCS), the Humboldt or Peru-Chile Current System (PCCS), and the Kuroshio-Oyashio Extension (KOE) region. POBEX investigators found that a dominant fraction of decadal variability in basin- and regional-scale salinity, nutrients, chlorophyll, and zooplankton taxa is explained by a newly discovered pattern of ocean-climate variability dubbed the North Pacific Gyre Oscillation (NPGO) and the Paciic Decadal Oscillation (PDO). NPGO dynamics are driven by atmospheric variability in the North Paciic and capture the decadal expression of Central Pacific El Niños in the extratropics, much as the PDO captures the low-frequency expression of eastern Pacific El Niños. By combining hindcasts of eddy-resolving ocean models over the period 1950-2008 with model passive tracers and long-term observations (e.g., CalCOFI, Line-P, Newport Hydrographic Line, Odate Collection), POBEX showed that the PDO and the NPGO combine to control low-frequency upwelling and alongshore transport dynamics in the North Pacific sector, while the eastern Paciic El Niño dominates in the South Pacific. Although different climate modes have diferent regional expressions, changes in vertical transport (e.g., upwelling) were found to explain the dominant nutrient and phytoplankton variability in the CCS, GOA, and PCCS, while changes in alongshore transport forced much of the observed long-term change in zooplankton species composition in the KOE as well as in the northern and southern CCS. In contrast, cross-shelf transport dynamics were linked to mesoscale eddy activity, driven by regional-scale dynamics that are largely decoupled from variations associated with the large-scale climate modes. Preliminary indings suggest that mesoscale eddies play a key role in ofshore transport of zooplankton and impact the life cycles of higher trophic levels (e.g., fish) in the CCS, PCCS, and GOA. Looking forward, POBEX results may guide the development of new modeling and observational strategies to establish mechanistic links among climate forcing, mesoscale circulation, and marine population dynamics. [ABSTRACT FROM AUTHOR]

Mean trophic level (MTL) is one of the most widely used indicators of marine ecosystem health. It usually represents the relative abundance of fished species across a spectrum of TLs. The reality, ubiquity, and causes of a general decline in the MTL of fisheries catch through time, and whether fisheries catch tracks ecosystem level changes, have engendered much attention. However, the consequences of such patterns for broader ecosystem structure and function remain virtually unexplored. Along the Pacific U.S. Coast, previous work has documented fluctuations and a slow increase in ecosystem MTL from 1977 to 2004. Here, we document a decline in the ecosystem MTL of groundfishes in the same ecosystem from 2003 to 2011, the proximate cause of which was a decrease in the biomass of higher TL groundfishes. Using a food web model, we illustrate how these shifts in ecosystem structure may have resulted in short term, positive responses by many lower TL species in the broader ecosystem. In the longer term, the model predicts that initial patterns of prey release may be tempered in part by lagged responses of other higher TL species, such as salmon and seabirds. Although ecosystem functions related to specific groups like piscivores (excluding high-TL groundfishes) changed, aggregate ecosystem functions altered little following the initial reorganization of biomass, probably due to functional redundancy within the predator guild. Efforts to manage and conserve marine ecosystems will benefit from a fuller consideration of the information content contained within, and implied by, fisheries-independent TL indicators. [ABSTRACT FROM AUTHOR]

Abstract: Jumbo squid (Dosidicus gigas) have greatly extended their range in the California Current System, where they forage on a variety of ecologically and economically important species that inhabit both coastal and offshore mesopelagic regions. Swimming abilities and behavior are important factors in assessing the impacts of this range expansion, particularly in regard to foraging in conjunction with onshore–offshore movement over the continental shelf. Here we describe a study of horizontal movements by jumbo squid along and across the continental shelf off Washington, USA, using acoustic tags in association with the Census of Marine Life's Pacific Ocean Shelf Tracking Program (POST) receiver arrays. We detected frequent movements along the shelf break, movement onto the shelf at night, and no evidence of movement as a cohesive school. Our results demonstrate feasibility of using acoustic tags and arrays to document horizontal movements of jumbo squid along and across the continental shelf. This is important in order to determine how those movements overlap with those of other ecologically and commercially important fish species. [Copyright &y& Elsevier]

Abstract: From 2002 to 2010, the jumbo squid (Dosidicus gigas) has been regularly encountered in large numbers throughout the California Current System (CCS). This species, usually found in subtropical waters, could affect coastal pelagic ecosystems and fisheries as both predator and prey. Neither the abundance of jumbo squid nor the optimal ocean conditions in which they flourish are well known. To understand better the potential impacts of this species on both commercial fisheries and on food-web structure we collected nearly 900 specimens from waters of the CCS, covering over 20° of latitude, over a range of depths and seasons. We used demographic information (size, sex, and maturity state) and analyzed stomach contents using morphological and molecular methods to best understand the foraging ecology of this species in different habitats of the CCS. Squid were found to consume a broad array of prey. Prey in offshore waters generally reflected the forage base reported in previous studies (mainly mesopelagic fishes and squids), whereas in more coastal waters (shelf, shelf break and slope habitats) squid foraged on a much broader mix that included substantial numbers of coastal pelagic fishes (Pacific herring and northern anchovy, as well as osmerids and salmonids in northern waters) and groundfish (Pacific hake, several species of rockfish and flatfish). We propose a seasonal movement pattern, based on size and maturity distributions along with qualitative patterns of presence or absence, and discuss the relevance of both the movement and distribution of jumbo squid over space and time. We find that jumbo squid are a generalist predator, which feeds primarily on small, pelagic or mesopelagic micronekton but also on larger fishes when they are available. We also conclude that interactions with and potential impacts on ecosystems likely vary over space and time, in response to both seasonal movement patterns and highly variable year-to-year abundance of the squid themselves. [Copyright &y& Elsevier]

The California Current Large Marine Ecosystem (CCLME), a temperate marine region dominated by episodic upwelling, is predicted to experience rapid environmental change in the future due to ocean acidification. Aragonite saturation state within the California Current System is predicted to decrease in the future, with near-permanent undersaturation conditions expected by the year 2050. Thus, the CCLME is a critical region to study due to the rapid rate of environmental change that resident organisms will experience and because of the economic and societal value of this coastal region. Recent efforts by a research consortium - the Ocean Margin Ecosystems Group for Acidification Studies (OMEGAS) - has begun to characterize a portion of the CCLME; both describing the mosaic of pH in coastal waters and examining the responses of key calcification-dependent benthic marine organisms to natural variation in pH and to changes in carbonate chemistry that are expected in the coming decades. In this review, we present the OMEGAS strategy of co-locating sensors and oceanographic observations with biological studies on benthic marine invertebrates, specifically measurements of functional traits such as calcification-related processes and genetic variation in populations that are locally adapted to conditions in a particular region of the coast. Highlighted in this contribution are (1) the OMEGAS sensor network that spans the west coast of the US from central Oregon to southern California, (2) initial findings of the carbonate chemistry amongst the OMEGAS study sites, (3) an overview of the biological data that describes the acclimatization and the adaptation capacity of key benthic marine invertebrates within the CCLME. [ABSTRACT FROM AUTHOR]

Abstract: Small pelagic fishes off southern California exhibit interannual variations in the regions they occupy. An enhanced understanding of these fluctuations could improve fisheries management and predictions of fish''s responses to climate change. We investigated dynamic height as a variable for identifying the spawning habitat of northern anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), and jack mackerel (Trachurus symmetricus). During cruises between 1998 and 2004, dynamic height was calculated from temperature and salinity profiles, while fish egg concentration was measured with obliquely towed bongo nets and the Continuous, Underway Fish Egg Sampler. Dynamic height ranged between 68 and 108cm, with values increasing offshore. The greatest probability of encountering anchovy, sardine, and jack mackerel eggs occurred at dynamic heights of 79–83cm, 84–89cm, and 89–99cm, respectively. Four mechanisms were proposed to explain how dynamic height affects egg distribution: (1) dynamic height is a proxy for upper water column temperature and salinity, which are known to influence spawning habitat. (2) Low dynamic heights are indicative of coastal upwelling, which increases primary and secondary productivity. (3) Egg concentration is greater at dynamic heights coincident with geostrophic currents that transport larvae to favorable habitats. (4) Eddies delineated by dynamic height contours retain eggs in productive habitats. To evaluate these mechanisms, a generalized linear model was constructed using dynamic height, temperature, salinity, chlorophyll, zooplankton volume, geostrophic currents, and eddies as independent variables. Dynamic height explained more variance than any other variable in models of sardine and anchovy spawning habitat. Together temperature, salinity, and chlorophyll accounted for 80–95% of the dynamic height effect, emphasizing the importance of the first two mechanisms. However, dynamic height remained statistically significant in the models of anchovy and jack mackerel spawning habitat after considering the effects of all other variables. Dynamic height shows promise as an ecological indicator of spawning habitat, because it integrates the effects of multiple oceanic variables, can be remotely sensed, and is predicted by ocean circulation models. [Copyright &y& Elsevier]

Abstract: Non-breeding sooty shearwaters are the most abundant seabird in the California Current Large Marine Ecosystem (CCLME) during boreal spring and summer months. This, combined with relatively great energy demands, reliance on patchy, shoaling prey (krill, squid, and forage fishes), and unconstrained mobility free from central-place-foraging demands—make shearwaters useful indicators of ecosystem variability. During 2008 and 2009, we used satellite telemetry to evaluate shearwater ranging patterns throughout the CCLME and specifically within the US Exclusive Economic Zone (EEZ) among birds captured at three locations: Columbia River Plume, WA; Monterey Bay, CA; and Santa Barbara Channel, CA. Shearwaters ranged throughout the entire CCLME from southeast Alaska to southern Baja California, Mexico. Within the EEZ during 2008 and 2009, shearwaters spent 68% and 46% of time over the shelf (<200m), 27% and 43% of time over the slope (200–1000m), and 5% and 11% of time over the continental rise and abyssal regions (>1000m), respectively. In 2008 and 2009, shearwaters spent 22% and 25% of their time in the EEZ within the five west coast National Marine Sanctuaries, respectively; high utilization occurred in non-sanctuary waters of the EEZ. Shearwater utilization distribution (based on the Brownian-bridge movement model) among sanctuaries was disproportionate according to sanctuary availability (based on area) within the EEZ. Shearwaters utilized the Monterey Bay sanctuary (2008, 2009) and the Channel Islands sanctuary (2009) disproportionately more than other sanctuaries. Although all five sanctuaries were used by shearwaters, waters outside sanctuary zones appeared significantly more important and likely supported large aggregations of shearwaters. Utilization distributions among individual birds from three discrete capture locations were variable and revealed greater similarity in space-use sharing within capture-location groupings and during 2008 when shearwaters were more aggregated than in 2009. We identified several regional “habitat hotspot” areas, including the Columbia River Plume, Cape Blanco, Monterey Bay, Estero/San Luis Obispo Bays, and the eastern Santa Barbara Channel through the inner Southern California Bight. [Copyright &y& Elsevier]

Abstract: Marine spatial planning and ecosystem models that aim to predict and protect fisheries and wildlife benefit greatly from syntheses of empirical information on physical and biological partitioning of marine ecosystems. Here, we develop spatially-explicit oceanographic and ecological descriptions of the central California Current region. To partition this region, we integrate data from 20years of shipboard surveys with satellite remote-sensing to characterize local seascapes of ecological significance, focusing on krill, other micronekton taxa, and top predators (seabirds and marine mammals). Specifically, we investigate if micronekton and predator assemblages co-vary spatially with mesoscale oceanographic conditions. The first principal component of environmental and micronekton seascapes indicates significant coupling between physics, primary productivity, and secondary and tertiary marine consumers. Subsequent principal components indicate latitudinal variability in niche-community space due to varying habitat characteristics between Monterey Bay (deep submarine canyon system) and the Gulf of the Farallones (extensive continental shelf), even though both of these sub-regions are located downstream from upwelling centers. Overall, we identified five ecologically important areas based on spatial integration of environmental and biotic features. These areas, characterized by proximity to upwelling centers, shallow pycnoclines, and high chlorophyll-a and krill concentrations, are potential areas of elevated trophic focusing for specific epipelagic and mesopelagic communities. This synthesis will benefit ecosystem-based management approaches for the central California Current, a region long-impacted by anthropogenic factors. [Copyright &y& Elsevier]

Processes that occur at mesoscale and submesoscale features such as eddies and fronts are important for marine ecosystem dynamics and biogeochemical fluxes. However, their impacts on the fate of biogenic organic carbon in coastal oceans are not well quantified because physical and biological interactions at such features are very complex with short time- and small spatial scales variability. As part of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER) Process studies in the southern California Current in October 2008, we sampled across a strong temperature and chlorophyll front (‘A-Front’) separating water masses with distinct hydrographic and biogeochemical characteristics and a modified biological assemblage at the frontal interface. Thorpe-scale analyses of the hydrographic data from a free-fall moving vessel profiler suggested an increased diapycnal diffusive nitrate flux at the front zone. Based on these field data, we use data-driven diagnostic biogeochemical models to quantify how the front-induced physical mixing influenced the production, grazing and transport of phytoplankton carbon in the southern California Current. Our results suggest that enhanced diffusive diapycnal fluxes of nutrients stimulated phytoplankton primary production at the front; this effect, together with reduced microzooplankton grazing, increased net growth of the phytoplankton community leading to locally enhanced biomass of large phytoplankton, such as diatoms, in the frontal zone. [ABSTRACT FROM AUTHOR]

Santora, J. A., Sydeman, W. J., Schroeder, I. D., Reiss, C. S., Wells, B. K., Field, J. C, Cossio, A. M., and Loeb, V. J. 2012. Krill space: a comparative assessment of mesoscale structuring in polar and temperate marine ecosystems. – ICES Journal of Marine Science, 69: .The spatial organization, mesoscale variability, and habitat associations of krill within portions of the Antarctic Peninsula and California Current marine ecosystems are compared. Using a decade of acoustic observations and remotely sensed oceanography (2000–2009), the hypothesis that mesoscale spatial organization of krill in both systems closely relates to geospatial variability of the shelf break and is non-linearly related to geostrophic flow and positively related to chlorophyll a (Chl a) is tested. Directional-dependence analysis to measure spatial variability of krill is used along with spatially explicit generalized additive models to quantify and compare the spatial relationships among krill and habitat characteristics in both systems. The results suggest the following aspects of krill spatial organization: (i) areas of dense aggregation, i.e. hot spots, are present in both systems and are orientated in the direction of the shelf break, (ii) moderate levels of eddy kinetic energy seem to concentrate krill in favourable habitats and lessen the likelihood of advection away from the system, and (iii) variable responses to surface Chl a concentration suggest that real-time Chl a values may not be useful as a global predictor of important krill habitat. The results provide valuable reference points for marine spatial management of krill and for refining ecosystem and foodweb models. [ABSTRACT FROM PUBLISHER]

Abstract: We analyzed variations in naturally occurring δ 15N in four species of zooplankton as an index of climate influences on pelagic food web structure in a major eastern boundary current ecosystem. Our analyses focused on two species of particle-grazing copepods (Calanus pacificus and Eucalanus californicus) and two species of carnivorous chaetognaths (Sagitta bierii and Sagitta euneritica), drawing on the CalCOFI zooplankton time series from both the southern and central sectors of the California Current System. We detected a significant difference between regions in average stable N isotope content of the two species of copepods, with δ 15N elevated by 0.5–1.1 per mil in the southern region, but no regional differences in the isotopic content of the chaetognaths. We address climate influences over a 54-year time period, on three different time scales: interannual (dominated by ENSO), decadal, and multi-decadal. Three of four species showed evidence of an ENSO-related isotopic shift toward increased 15N during El Niño conditions. In addition, in Southern California waters, C. pacificus and S. euneritica showed elevated δ 15N in the warm phase of the NE Pacific between 1978 and 1998 relative to the preceding and following time periods. When considered over the entire 5½ decades treated here, for most species there was remarkable long-term stability in stable isotope content in both southern and central California waters, despite interannual and decadal perturbations. Only E. californicus in the southern sector showed a significant downward secular trend in δ 15N. Variability of δ 15N in 3 species covaried with the average nitrate concentration in the mixed layer, suggesting altered nitrate utilization at the base of the food web as a primary mechanism underlying interannual changes in zooplankton isotopic content. [Copyright &y& Elsevier]

Abstract: The wide availability of ECOPATH data sets provides a valuable resource for the comparative analysis of marine ecosystems. We show how to derive a bottom–up transform from the top–down ECOPATH; couple this to a simple microbial web with physical forcing; and use the end-to-end model (E2E) for scenario construction. This steady state format also provides a framework and initial conditions for different dynamic simulations. This model can be applied to shelf ecosystems with a wide range of physical forcing, coupled benthic/pelagic food webs, and nutrient recycling. We illustrate the general application and the specific problems by transforming an ECOPATH model for the Northern California Current (NCC). We adapt results on the upwelling regime to provide estimates of physical fluxes and use these to show the consequences of different upwelling rates combined with variable retention mechanism for plankton, for the productivity of fish and other top predators; and for the resilience of the ecosystem. Finally we show how the effects of inter-annual to decadal variations in upwelling on fishery yields can be studied using dynamic simulations with different prey–predator relations. The general conclusion is that the nature of the physical regimes for shelf ecosystems cannot be ignored in comparing end-to-end representations of these food webs. [Copyright &y& Elsevier]

Forecasting the ecological effects of climate change on marine species is critical for informing greenhouse gas mitigation targets and developing marine conservation strategies that remain effective and increase species' resilience under changing climate conditions. Highly productive coastal upwelling systems are predicted to experience substantial effects from climate change, making them priorities for ecological forecasting. We used a population modeling approach to examine the consequences of ocean climate change in the California Current upwelling ecosystem on the population growth rate of the planktivorous seabird Cassin's auklet ( Ptychoramphus aleuticus), a demographically sensitive indicator of marine climate change. We use future climate projections for sea surface temperature and upwelling intensity from a regional climate model to forecast changes in the population growth rate of the auklet population at the important Farallon Island colony in central California. Our study projected that the auklet population growth rate will experience an absolute decline of 11–45% by the end of the century, placing this population on a trajectory toward extinction. In addition, future changes in upwelling intensity and timing of peak upwelling are likely to vary across auklet foraging regions in the California Current Ecosystem (CCE), producing a mosaic of climate conditions and ecological impacts across the auklet range. Overall, the Farallon Island Cassin's auklet population has been declining during recent decades, and ocean climate change in this century under a mid-level emissions scenario is projected to accelerate this decline, leading toward population extinction. Because our study species has proven to be a sensitive indicator of oceanographic conditions in the CCE and a powerful predictor of the abundance of other important predators (i.e. salmon), the significant impacts we predicted for the Cassin's auklet provide insights into the consequences that ocean climate change may have for other plankton predators in this system. [ABSTRACT FROM AUTHOR]

The article presents a study which compared the methods for identifying the spring transition in the California Current System (CCS). The study examined the relationships between recruitment and the timing of spring transition of Pacific ocean perch Sebastes alutus and sablefish Anoplopoma fimbria to find the biological implications of the said methods. It found that the spring transition in northern CCS and in central and southern regions differ significantly. Moreover, it suggests that the dates of spring transition can be defined by combining the said methods during the transition period.

The article presents a study which discusses the variations in the small-to meso-scale abundance and distribution of seabird species in Northern California Current. It mentions that among the species being examined include the black-footed albatross Phoebastria nigripes, pink-footed shearwater Puffinus creatopus, sooty shearwater Puffinus griseus and common murre Uria aalge. It relates that results in the findings indicated the importance of adding spatially explicit data on predator and prey species.

Upwelling of nutrient-rich, subsurface water sustains high productivity in the ocean's eastern boundary currents. These ecosystems support a rate of fish harvest nearly 100 times the global mean and account for >20% of the world's marine fish catch. Environmental variability is thought to be the major cause of the decadal-scale biomass fluctuations characteristic of fish populations in these regions, but the mechanisms relating atmospheric physics to fish production remain unexplained. Two atmospheric conditions induce different types of upwelling in these ecosystems: coastal, alongshore wind stress, resulting in rapid upwelling (with high vertical velocity, w); and wind-stress curl, resulting in slower upwelling (low w). We show that the level of wind-stress curl has increased and that production of Pacific sardine (Sardinops sagax) varies with wind-stress curl over the past six decades. The extent of isopycnal shoaling, nutricline depth, and chlorophyll concentration in the upper ocean also correlate positively with wind-stress curl. The size structure of plankton assemblages is related to the rate of wind-forced upwelling, and sardine feed efficiently on small plankters generated by slow upwelling. Upwelling rate is a fundamental determinant of the biological structure and production in coastal pelagic ecosystems, and future changes in the magnitude and spatial gradient of wind stress may have important and differing effects on these ecosystems. Understanding of the biological mechanisms relating fisheries production to environmental variability is essential for wise management of marine resources under a changing climate. [ABSTRACT FROM AUTHOR]

In this study we analyzed the diets of 26 nekton species collected from two years (2000 and 2002) off Oregon and northern California to describe dominant nekton trophic groups of the northern California Current (NCC) pelagic ecosystem. We also examined interannual variation in the diets of three nekton species. Cluster analysis of predator diets resulted in nekton trophic groups based on the consumption of copepods, euphausiids, brachyuran larvae, larval-juvenile fishes, and adult nekton. However, many fish within trophic groups consumed prey from multiple trophic levels-euphausiids being the most widely consumed. Comparison of diets between years showed that most variation occurred with changes in the contribution of euphausiids and brachyuran larvae to nekton diets. The importance of euphausiids and other crustacean prey to nekton indicates that omnivory is an important characteristic of the NCC food web; however it may change during periods of lower or higher upwelling and ecosystem production. [ABSTRACT FROM AUTHOR]

The abundance and population density of cetaceans along the U.S. west coast were estimated from ship surveys conducted in the summer and fall of 1991, 1993, 1996, 2001, and 2005 by using multiple-covariate, line-transect analyses. Overall, approximately 556,000 cetaceans of 21 species were estimated to be in the 1,141,800-km² study area. Delphinoids (Delphinidae and Phocoenidae), the most abundant group, numbered ~540,000 individuals. Abundance in other taxonomic groups included ~5800 baleen whales (Mysticeti), ~7000 beaked whales (Ziphiidae), and ~3200 sperm whales (Physeteridae). This study provides the longest time series of abundance estimates that includes all the cetacean species in any marine ecosystem. These estimates will be used to interpret the impacts of human-caused mortality (such as that documented in fishery bycatch and that caused by ship strikes and other means) and to evaluate the ecological role of cetaceans in the California Current ecosystem. [ABSTRACT FROM AUTHOR]

Because flow in the California Current is unidirectional for months, larvae of coastal species may drift and settle downstream of their parents, potentially causing the parental population to go extinct from upstream to downstream; this is a marine equivalent of the drift paradox in streams. Unidirectional larval drift might, however, be minimized by when, where, and how organisms reproduce. We compiled data on California Current fishes (89 nearshore, 65 shelf/slope) and benthic crustaceans (35 nearshore, 15 shelf/slope) and found three unique sets of life history traits displayed by (1) shelf/slope species, (2) nearshore pelagic-spawning fishes (all from the Southern California Bight [SCB] and Baja California), and (3) all other nearshore species. Pelagic larval durations (PD) of shelf/slope species are long (∼136 d); offspring are pelagic winter through summer and are found at depth below the mixed layer offshore. Offspring experience northward flow in winter and southward flow in spring/summer, perhaps minimizing net alongshore drift. Adults are both long-lived and highly fecund. Nearshore species have short PDs (∼45 d), and offspring are pelagic during spring/summer upwelling and are found nearshore and near the bottom. Nearshore larvae may experience southward flow during up welling and northward flow during relaxation events, minimizing net alongshore transport. Nearshore species have shorter lives and are less fecund than shelf/slope species. Nearshore pelagic-spawning fishes (all from the SCB and Baja) have short PDs (∼48 d), but in contrast to other nearshore species, their larvae are pelagic from spring into fall and are found far from shore. Adults are long-lived, highly fecund, and have numerous broods per year. These life history traits may have evolved to exploit eddies and countercurrents present in the SCB and off Baja for larval retention. Each set of life history traits appears to improve chances of offspring recruiting to parental populations. The pelagic phase, rather than being dispersive, may be selected to achieve a migration between larval pelagic and adult benthic habitats. [ABSTRACT FROM AUTHOR]

The article discusses trophic mass balance models of productive fishing grounds of four largest upwelling areas including northern Humboldt Current, northern Benguela Current and southern Canary Current to catch marine fish. It discusses that the model allowed to assess ecological sustainability of a fishery. It also mentions the model addresses the Code of Conduct for Responsible Fisheries published by the Food and Agricultural Organization of the United Nations.

The biological productivity and diversity of the California Current System (CCS) is at the leading edge of major emerging climate trends, including hypoxia and acidification. We present results from a hindcast simulation (reanalysis) of an eddy-resolving oceanic physical-biogeochemical model of the CCS, to characterize its mean state and its patterns and drivers of variability in marine biogeochemical and ecosystem processes from 1995 to 2010. This is a companion paper to a physical analysis in Renault et al. (2021). The model reproduces long-term mean distributions of key ecosystem metrics, including surface nutrients and productivity and subsurface O 2 and carbonate undersaturation. The spatial patterns of Net Primary Productivity (NPP) are broadly consistent with measured and remotely sensed rates, and they reflect a predominant limitation by nitrogen, with seasonal and episodic limitation by Fe nearshore in the central CCS, and in the open ocean northern CCS. The vertical distribution of NPP is governed by the trade-off between nutrient and light limitation, a balance that reproduces and explains the observed spatial variations in the depth of the deep Chl maximum. The seasonal to interannual variability of biogeochemical properties and rates is also well captured by model simulations. Because of the prevailing nutrient limitation, fluctuations in the depth of the pycnocline and associated nutricline are the leading single factor explaining interannual variability in the interior biogeochemical state, and the relationships between density and biogeochemical rates and tracers are consistent between model and observations. The magnitude and relationship between density structure and biogeochemical processes is illustrated by the 1997–98 El Niño event, which faithfully reproduces the single largest deviation from the mean state in the simulated period. A slower decadal shoaling of the pycnocline also accounts for the concomitant trends in hypoxic and corrosive conditions on the shelf. The resulting variability is key to understanding the vulnerability of marine species to oceanic change, and to the detection of such changes, soon projected to exceed the range of conditions in the past century. [ABSTRACT FROM AUTHOR]

The article focuses on the presence of anoxia in the California Current large marine ecosystem in the U.S. West Coast. It cites that the increase of anoxia indicates perturbations to the structure and functioning of coastal marine ecosystems. Moreover, it is noted that the emergence of anoxia has also been accompanied by the rise of hypoxia which would affect demersal fish and invertebrate communities in the waters. According to a study, the onset of hypoxia could affect fluctuations in atmosphere-ocean presses, intensity of wind stress and coastal respiration.