Bottom-up control of sardine and anchovy population cycles in the canary current: insights from an end-to-end model simulation

Sardine and anchovy can exhibit dramatic decadal-scale shifts in abundance in response to climate variability. Sharpe declines of these populations entail particularly serious commercial and ecological consequences in eastern boundary current ecosystems, where they sustain major world fisheries and provide the forage for a broad variety of predators. Understanding the mechanisms and environmental forcing that drive the observed fish variability remains a challenging problem. The modelling study presented here provides an approach that bridges a comprehensive database with an end-to-end modelling framework enabling the investigation of the sources of variability of sardine and anchovy in the Canary Current System. Different biological traits and behaviour prescribed for sardine and anchovy gave rise to different distribution and displacements of the populations, but to a rather synchronous variability in terms of abundance and biomass, in qualitative agreement with historical landing records. Analysis of years with anomalously high increase and decline of the adult population points to food availability (instead of temperature or other environmental drivers) as the main environmental factor determining recruitment for both sardine (via spawning and survival of feeding age-0 individuals) and anchovy (via survival of feeding age-0). Consistent with this, the two species thrive under enhanced upwelling-favourable winds, but only up to some threshold of the wind velocity beyond which larval drift mortality exceeds the positive effect of the extra food supply. Based on the analysis of the simulation, we found that anchovy larvae are particularly vulnerable to enhanced wind-driven advection, and as such do better with more moderate upwelling than sardines.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Population distribution and biomass variability of sardine and anchovy in the Canary current system as simulated by an end-to-end coupled model

Small pelagic fishes as sardine and anchovy account for as much as 20-25% of the world fisheries catch. They are particularly abundant in the four major eastern boundary upwelling ecosystems, where high levels of biological productivity are sustained by the supply of nutrient-rich water from beneath the photic zone. An intrinsic and puzzling feature of small pelagic fish is the large fluctuations of their population, typically occurring at decadal scales. The causes for such fluctuations have been extensively analyzed and discussed in the literature, yet our understanding of the mechanism involved is very limited. End-to-end models are emerging tools useful to test hypothesis for such fish population variability or to gain new insights into the problem. This comprehensive and complex model approach is now becoming possible largely thanks to the present-day computer power. This contribution focuses on the population dynamics of sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) in the Canary Current Upwelling Ecosystem. We describe and present the results of an end-to-end coupled model simulation including these two small pelagic species. The end-to-end application includes three model components: the ROMS circulation sub-model, the lower trophic ecosystem sub-model NEMURO, and a recently developed individual-based model for the fish (Rose et al. 2015; Fiechter et al. 2015). The computational grid for the three models covers NW Africa and the Western Iberian Peninsula at a spatial resolution of 12 km. This resolution is sufficient for certain eddy variability to occur in ROMS. Different biological traits were prescribed for anchovy and sardine: temperature optimum, diet preferences, and the onset and duration of the spawning season, among others. A hind-cast simulation of the period 1958-2007 was carried out. Model results reveal a fairly different behavior of sardine and anchovy. Anchovies gather off the northern part of Morocco and the Gulf of Cadiz, whereas sardines appear more scattered across the domain, further offshore, and further south, where upwelling favorable conditions take place year round. Both species exhibit decadal-scale fluctuations in both the location of the center of mass of the population and their biomass abundance; the latter being reasonably correlated with historical landing records.Universidad de Málaga. Campus de Excelencia Internacional del Mar CEIMAR. Campus de Excelencia Andalucía Tec

Advances in Physical, Biological, and Coupled Ocean Models During the US GLOBEC Program

From the planning days preceding the establishment of the US Global Ocean Ecosystem Dynamics (GLOBEC) program, modeling was recognized as one of the program’s pillars. In particular, predictions of future ecosystem states in an evolving climate system required new interdisciplinary approaches that brought together physicists, biologists, modelers, and observational scientists. The GLOBEC program coincided with, took advantage of, and contributed to significant advances in ocean modeling capabilities. During the GLOBEC years, computer power increased substantially to the point where coupled physical-biological models, at resolutions where important interactions are resolved, became feasible. Ocean models were maturing so that complex coastal processes were explicitly represented, and advances in different ways of modeling the biosphere, from Lagrangian individuals to Eulerian community-based, multitrophic models, were emerging. The US GLOBEC program addressed the question: How can we use all these developments to help us understand how ecosystems will respond to climate change? This paper includes a review of state-of-the-science modeling at the onset of the GLOBEC program and highlights the evolution of physical and biological models used for the program’s target regions and species throughout the GLOBEC years, 1992–2012

Application of a data-assimilative regional ocean modeling system for assessing California Current System ocean conditions, krill, and juvenile rockfish interannual variability

Abstract To be robust and informative, marine ecosystem models and assessments require parameterized biophysical relationships that rely on realistic water column characteristics at appropriate spatial and temporal scales. We examine how hydrographic properties off California from 1990 through 2010 during late winter and spring correspond to krill and juvenile rockfish (Sebastes spp.) abundances. We evaluated coherence among temperature, salinity, depth of 26.0 potential density isopycnal, and stratification strength at regionally and monthly time scales derived from shipboard and mooring observations, and a data-assimilative Regional Ocean Model System reanalysis. The reanalysis captures spatiotemporal physical variability of coastal ocean conditions in winter and spring months and elucidates mechanisms connecting the spatial and temporal upwelling and transport dynamics on observed krill and rockfish abundances in spring. This provides evidence for a mechanistic connection between the phenology of upwelling in the California Current System and seasonal development of the shelf ecosystem

Projecting marine mammal distribution in a changing climate

Climate-related shifts in marine mammal range and distribution have been observed in some populations; however, the nature and magnitude of future responses are uncertain in novel environments projected under climate change. This poses a challenge for agencies charged with management and conservation of these species. Specialized diets, restricted ranges, or reliance on specific substrates or sites (e.g., for pupping) make many marine mammal populations particularly vulnerable to climate change. High-latitude, predominantly ice-obligate, species have experienced some of the largest changes in habitat and distribution and these are expected to continue. Efforts to predict and project marine mammal distributions to date have emphasized data-driven statistical habitat models. These have proven successful for short time-scale (e.g., seasonal) management activities, but confidence that such relationships will hold for multi-decade projections and novel environments is limited. Recent advances in mechanistic modeling of marine mammals (i.e., models that rely on robust physiological and ecological principles expected to hold under climate change) may address this limitation. The success of such approaches rests on continued advances in marine mammal ecology, behavior, and physiology together with improved regional climate projections. The broad scope of this challenge suggests initial priorities be placed on vulnerable species or populations (those already experiencing declines or projected to undergo ecological shifts resulting from climate changes that are consistent across climate projections) and species or populations for which ample data already exist (with the hope that these may inform climate change sensitivities in less well observed species or populations elsewhere). The sustained monitoring networks, novel observations, and modeling advances required to more confidently project marine mammal distributions in a changing climate will ultimately benefit management decisions across time-scales, further promoting the resilience of marine mammal populations

Seasonal-to-interannual prediction of North American coastal marine ecosystems: forecast methods, mechanisms of predictability, and priority developments

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Jacox, M. G., Alexander, M. A., Siedlecki, S., Chen, K., Kwon, Y., Brodie, S., Ortiz, I., Tommasi, D., Widlansky, M. J., Barrie, D., Capotondi, A., Cheng, W., Di Lorenzo, E., Edwards, C., Fiechter, J., Fratantoni, P., Hazen, E. L., Hermann, A. J., Kumar, A., Miller, A. J., Pirhalla, D., Buil, M. P., Ray, S., Sheridan, S. C., Subramanian, A., Thompson, P., Thorne, L., Annamalai, H., Aydin, K., Bograd, S. J., Griffis, R. B., Kearney, K., Kim, H., Mariotti, A., Merrifield, M., & Rykaczewski, R. Seasonal-to-interannual prediction of North American coastal marine ecosystems: forecast methods, mechanisms of predictability, and priority developments. Progress in Oceanography, 183, (2020): 102307, doi:10.1016/j.pocean.2020.102307.Marine ecosystem forecasting is an area of active research and rapid development. Promise has been shown for skillful prediction of physical, biogeochemical, and ecological variables on a range of timescales, suggesting potential for forecasts to aid in the management of living marine resources and coastal communities. However, the mechanisms underlying forecast skill in marine ecosystems are often poorly understood, and many forecasts, especially for biological variables, rely on empirical statistical relationships developed from historical observations. Here, we review statistical and dynamical marine ecosystem forecasting methods and highlight examples of their application along U.S. coastlines for seasonal-to-interannual (1–24 month) prediction of properties ranging from coastal sea level to marine top predator distributions. We then describe known mechanisms governing marine ecosystem predictability and how they have been used in forecasts to date. These mechanisms include physical atmospheric and oceanic processes, biogeochemical and ecological responses to physical forcing, and intrinsic characteristics of species themselves. In reviewing the state of the knowledge on forecasting techniques and mechanisms underlying marine ecosystem predictability, we aim to facilitate forecast development and uptake by (i) identifying methods and processes that can be exploited for development of skillful regional forecasts, (ii) informing priorities for forecast development and verification, and (iii) improving understanding of conditional forecast skill (i.e., a priori knowledge of whether a forecast is likely to be skillful). While we focus primarily on coastal marine ecosystems surrounding North America (and the U.S. in particular), we detail forecast methods, physical and biological mechanisms, and priority developments that are globally relevant.This study was supported by the NOAA Climate Program Office’s Modeling, Analysis, Predictions, and Projections (MAPP) program through grants NA17OAR4310108, NA17OAR4310112, NA17OAR4310111, NA17OAR4310110, NA17OAR4310109, NA17OAR4310104, NA17OAR4310106, and NA17OAR4310113. This paper is a product of the NOAA/MAPP Marine Prediction Task Force

Data from: Krill hotspot formation and phenology in the California Current Ecosystem

In the California Current Ecosystem (CCE), krill represent a key link between primary production and higher trophic level species owing to their central position in the food web and tendency to form dense aggregations. However, the strongly advective circulation associated with coastal upwelling may spatiotemporally decouple the occurrence and persistence of krill hotspots from phytoplankton biomass and nutrient sources. Results from a physical-biological model provide insights into fundamental mechanisms controlling the phenology of krill hotspots in the CCE and their sensitivity to alongshore variations in primary production and ocean currents. The model solution indicates that dynamics controlling krill hotspot formation, intensity and persistence are strongly heterogeneous and must be understood in the context of local alongshore variations in coastal upwelling, modulated by regional circulation patterns. Furthermore, the model suggests that regions promoting krill aggregations in the CCE coincide with increased observed abundances of key marine mammal and seabird species.All necessary information to use this dataset is contained in the metadata (variable name, units, missing value flag, etc.). Funding provided by: National Aeronautics and Space AdministrationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000104Award Number: 80NSSC17K0574Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: OCE1566623Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: OCE1635315This dataset is a subset of a coupled physical-biogeochemcial model for the central California Current upwelling system. The physical model is an implementation of the Regional Ocean Modelling System (ROMS; www.myroms.org) coupled to NEMUCSC, a customized version of the North Pacific Ecosystem Model for Understanding Regional Oceanography (NEMURO). The NEMUCSC biogeochemical model includes three limiting macro-nutrients, two phytoplankton functional groups, three zooplankton size-classes, and three detritus pools. To better represent the combined effects of regional circulation patterns and local upwelling intensity on alongshore biophysical properties, the model downscales a data-assimilative physical reanalysis at 1/10° (~10 km) resolution for the broader California Current system to a higher 1/30° (~3 km) resolution domain for the central California Current region. A subset of variables were extracted from the full daily model output at various depths and subsequently averaged monthly for 1990-2010 using Ferret V7.1 (http://ferret.pmel.noaa.gov/Ferret). The dataset is in NetCDF4 format (CF-1.4 compliant) with metadata describing each variable name and associated units on the native ROMS grid

Living on the edge of the Florida current: A study of the physical processes affecting primary production and larval transport

Regional (ca. 1000 km) and local (ca. 100 km) scale, three-dimensional, time-dependent, coastal ocean circulation models, coupled with lower trophic level ecosystem and Lagrangian larval transport models, have been implemented for the East Florida Shelf (EFS) with sufficient horizontal and vertical resolution to admit the dominant physical and biological processes, and to conduct model-observations comparisons. Consequently, the results provide reliable new information about the impact of the variable Florida Current (FC) circulation on physical and biological processes over timescales ranging from daily to seasonal. At the regional scale, simulations with a mesoscale-resolving (ca. 4 to 10 km) coupled ocean circulation-ecosystem model provide estimates of the frequency, intensity, duration, and property transport of upwelling events along the EFS, and help identify their underlying mechanisms. North of 27°N, FC meanders and FC frontal eddies (FCFE) are the main contributors to the mesoscale variability. FCFE events also impact primary production at the shelfbreak, resulting in short-lived phytoplankton blooms with large amplitude variations on weekly and monthly timescales. At the local scale, simulations with a high-resolution (ca. 800 m) ocean circulation model, combined with targeted in-situ observations, provide estimates of alongshelf and cross-shelf transport of larval marine organisms along the Upper Florida Keys. For AUG 2006, alongshelf advection was mainly poleward and due to the subtidal flow of the FC, while cross-shelf advection was mainly onshore and due to wind-driven currents. Typical advection distances were of the order of 10 to 50 km for pelagic larval durations of ca. one week. Probability density functions indicated a significant onshore transport component, thereby suggesting that local retention was probably the dominant mechanism supplying coral larvae to the reefs on a weekly timescale. Overall, the results set the stage for future ecological forecasting efforts in the EFS region, including the implementation of more complex ecosystem and Lagrangian larval transport models. By identifying the spatial and temporal scales at which physical and biological processes occur along the EFS, the validated simulations also provide a rational framework for improving the design of coastal ocean observing systems.</p

Numerical study of platelet transport in flowing blood

M.S.David N. K