Effect of life history strategy, environmental variability, and overexploitation on the genetic diversity of pelagic fish populations

1999 ◽  
Vol 56 (8) ◽  
pp. 1376-1388 ◽  
Author(s):  
Oscar E Gaggiotti ◽  
Russel D Vetter
Keyword(s):  
Life History ◽  
Genetic Variability ◽  
Environmental Changes ◽  
Current System ◽  
Reproductive Value ◽  
California Current System ◽  
Environmental Fluctuations ◽  
Pacific Sardine ◽  
Northern Anchovy ◽  
The Impact

We study the effect of recruitment failures and variance in reproductive success on effective population size (Ne) in populations with type III survivorship curves. Special emphasis is put on determining the causes for the large differences in the genetic variability between populations of Pacific sardine (Sardinops sagax) and northern anchovy (Engraulis mordax). The results indicate that moderate differences in life history between ecologically related species can lead to substantial differences in Ne. The effect of fluctuations in vital rate parameters induced by environmental changes on Ne depends on the life history of each species. The ratio of Ne to census size is directly proportional to the total reproductive value of a population, but the sensitivity of this ratio to environmental fluctuations is inversely proportional to the generation overlap. The larger the generation overlap, the smaller the impact of environmental fluctuations on the level of genetic variability maintained by a population. The large difference in heterozygosity between Pacific sardine and northern anchovy populations is likely due to both life history differences between the two species and a recent arrival (founder event) of the Pacific sardine population to the California Current System.

scholarly journals Using Saildrones to Validate Satellite-Derived Sea Surface Salinity and Sea Surface Temperature along the California/Baja Coast

2019 ◽  
Vol 11 (17) ◽  
pp. 1964 ◽  
Author(s):  
Jorge Vazquez-Cuervo ◽  
Jose Gomez-Valdes ◽  
Marouan Bouali ◽  
Luis Miranda ◽  
Tom Van der Stocken ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Current System ◽  
California Current ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
California Current System ◽  
The Impact ◽  
Buoy Measurements

Traditional ways of validating satellite-derived sea surface temperature (SST) and sea surface salinity (SSS) products by comparing with buoy measurements, do not allow for evaluating the impact of mesoscale-to-submesoscale variability. We present the validation of remotely sensed SST and SSS data against the unmanned surface vehicle (USV)—called Saildrone—measurements from the 60 day 2018 Baja California campaign. More specifically, biases and root mean square differences (RMSDs) were calculated between USV-derived SST and SSS values, and six satellite-derived SST (MUR, OSTIA, CMC, K10, REMSS, and DMI) and three SSS (JPLSMAP, RSS40, RSS70) products. Biases between the USV SST and OSTIA/CMC/DMI were approximately zero, while MUR showed a bias of 0.3 °C. The OSTIA showed the smallest RMSD of 0.39 °C, while DMI had the largest RMSD of 0.5 °C. An RMSD of 0.4 °C between Saildrone SST and the satellite-derived products could be explained by the diurnal and sub-daily variability in USV SST, which currently cannot be resolved by remote sensing measurements. SSS showed fresh biases of 0.1 PSU for JPLSMAP and 0.2 PSU and 0.3 PSU for RMSS40 and RSS70 respectively. SST and SSS showed peaks in coherence at 100 km, most likely associated with the variability of the California Current System.

scholarly journals Climate-driven aerobic habitat loss in the California Current System

2020 ◽  
Vol 6 (20) ◽  
pp. eaay3188 ◽  
Author(s):  
Evan M. Howard ◽  
Justin L. Penn ◽  
Hartmut Frenzel ◽  
Brad A. Seibel ◽  
Daniele Bianchi ◽  
...  
Keyword(s):  
Habitat Loss ◽  
Current System ◽  
Marine Ecosystem ◽  
Oxygen Demand ◽  
California Current ◽  
Regional Variability ◽  
California Current System ◽  
Large Fluctuations ◽  
Northern Anchovy ◽  
Species Specific

Climate warming is expected to intensify hypoxia in the California Current System (CCS), threatening its diverse and productive marine ecosystem. We analyzed past regional variability and future changes in the Metabolic Index (Φ), a species-specific measure of the environment’s capacity to meet temperature-dependent organismal oxygen demand. Across the traits of diverse animals, Φ exhibits strong seasonal to interdecadal variations throughout the CCS, implying that resident species already experience large fluctuations in available aerobic habitat. For a key CCS species, northern anchovy, the long-term biogeographic distribution and decadal fluctuations in abundance are both highly coherent with aerobic habitat volume. Ocean warming and oxygen loss by 2100 are projected to decrease Φ below critical levels in 30 to 50% of anchovies’ present range, including complete loss of aerobic habitat—and thus likely extirpation—from the southern CCS. Aerobic habitat loss will vary widely across the traits of CCS taxa, disrupting ecological interactions throughout the region.

scholarly journals The Physical Structure and Behavior of the California Current System

2020 ◽  
Author(s):  
Lionel Renault ◽  
James C. McWilliams ◽  
Alexandre Jousse ◽  
Curtis Deutsch ◽  
Hartmut Frenzel ◽  
...  
Keyword(s):  
High Resolution ◽  
Boundary Conditions ◽  
Current System ◽  
Mesoscale Eddy ◽  
California Current ◽  
Open Boundary ◽  
Biogeochemical Model ◽  
California Current System ◽  
Synoptic Wind ◽  
The Impact

AbstractThis paper is the first of two that present a 16-year reanalysis solution from a coupled physical and biogeochemical model of the California Current System (CCS) along the U. S. West Coast and validate the solution with respect to mean and seasonal fields and, to a lesser degree, eddy variability. Its companion paper is Deutsch et al. (2019a). The intent is to construct and demonstrate a modeling tool that will be used for mechanistic explanations, attributive causal assessments, and forecasts of future evolution for circulation and biogeochemistry, with particular attention to the increasing oceanic stratification, deoxygenation, and acidification. A well-resolved mesoscale (dx = 4 km) simulation of the CCS circulation is made with the Regional Oceanic Modeling System over a reanalysis period of 16 years from 1995 to 2010. The oceanic solution is forced by a high-resolution (dx = 6 km) regional configuration of the Weather and Research Forecast (WRF) atmospheric model. Both of these high-resolution regional oceanic and atmospheric simulations are forced by lateral open boundary conditions taken from larger-domain, coarser-resolution parent simulations that themselves have boundary conditions from the Mercator and Climate Forecast System reanalyses, respectively. We first show good agreement between the simulated atmospheric forcing of the ocean and satellite observations for the spatial patterns and seasonal variability of the cloud cover and for the surface fluxes of momentum, heat, and freshwater. The simulated oceanic physical fields are then evaluated with satellite and in situ observations. The simulation reproduces the main structure of the climatological upwelling front and cross-shore isopycnal slopes, the mean current patterns (including the California Undercurrent), and the seasonal and interannual variability. It also shows agreement between the mesoscale eddy activity and the wind-work energy exchange between the ocean and atmosphere modulated by influences of surface current on surface stress. Finally, the impact of using a high frequency wind forcing is assessed for the importance of synoptic wind variability to realistically represent oceanic mesoscale activity and ageostrophic inertial currents.

scholarly journals Using Saildrones to Validate Satellite-Derived Sea Surface Salinity and Sea Surface Temperature along the California/Baja Coast

2019 ◽  
Author(s):  
Jorge Vazquez-Cuervo ◽  
Jose Gomez-Valdes ◽  
Marouan Bouali ◽  
Luis Miranda ◽  
Tom Van der Stocken ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Current System ◽  
Local Maximum ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
California Current System ◽  
Daily Variability ◽  
The Impact

Traditional ways of validating satellite-derived sea surface temperature (SST) and sea surface salinity (SSS) products, using comparisons with buoy measurements, do not allow for evaluating the impact of mesoscale to submesoscale variability. Here we present the validation of remotely-sensed SST and SSS data against the unmanned surface vehicle (USV) – Saildrone – measurements from the Spring 2018 Baja deployment. More specifically, biases and root mean square differences (RMSD) were calculated between USV-derived SST and SSS values, and six satellite-derived SST (MUR, OSTIA, CMC, K10, REMSS, and DMI) and three SSS (JPLSMAP, RSS40, RSS70) products. Biases between the USV SST and OSTIA/CMC/DMI were approximately zero while MUR showed a bias of 0.2C. OSTIA showed the smallest RMSD of 0.36C while DMI had the largest RMSD of 0.5C. An RMSD of 0.4C between Saildrone SST and the satellite-derived products could be explained by the daily variability in USV SST which currently cannot be resolved by remote sensing measurements. For SSS, values from the JPLSMAP product showed saltier biases of 0.2 PSU, while RSS40 and RSS70 showed fresh biases of 0.3 PSU. An RMSD of 0.4 PSU could not be explained solely by the daily variability of the USV-derived SSS. Coherences were significant at the longer wavelengths, with a local maximum at 100 km that is most likely associated with the mesoscale turbulence in the California Current System.

scholarly journals Antagonistic effects of long- and short-term environmental variation on species coexistence

2021 ◽  
Vol 288 (1958) ◽  
pp. 20211491
Author(s):  
Ming Liu ◽  
Dustin R. Rubenstein ◽  
Siew Ann Cheong ◽  
Sheng-Feng Shen
Keyword(s):  
Species Coexistence ◽  
Environmental Changes ◽  
Environmental Variation ◽  
Ecological Impacts ◽  
Short Term ◽  
Term Variation ◽  
Environmental Fluctuations ◽  
Time Periods ◽  
The Impact

Assessing the impact of environmental fluctuations on species coexistence is critical for understanding biodiversity loss and the ecological impacts of climate change. Yet determining how properties like the intensity, frequency or duration of environmental fluctuations influence species coexistence remains challenging, presumably because previous studies have focused on indefinite coexistence. Here, we model the impact of environmental fluctuations at different temporal scales on species coexistence over a finite time period by employing the concepts of time-windowed averaging and performance curves to incorporate temporal niche differences within a stochastic Lotka–Volterra model. We discover that short- and long-term environmental variability has contrasting effects on transient species coexistence, such that short-term variation favours species coexistence, whereas long-term variation promotes competitive exclusion. This dichotomy occurs because small samples (e.g. environmental changes over long time periods) are more likely to show large deviations from the expected mean and are more difficult to predict than large samples (e.g. environmental changes over short time periods), as described in the central limit theorem. Consequently, we show that the complex set of relationships among environmental fluctuations and species coexistence found in previous studies can all be synthesized within a general framework by explicitly considering both long- and short-term environmental variation.

The impact of global warming on the upwellings and primary productivity at the southern limb of the California Current, Baja California, Mexico

2020 ◽  
Author(s):  
Jose Carriquiry ◽  
Christina Treinen-Crespo ◽  
Julio Villaescusa ◽  
Ann Pearson ◽  
Loic Barbara
Keyword(s):  
Primary Productivity ◽  
Large Scale ◽  
Baja California ◽  
Coastal Upwelling ◽  
Current System ◽  
California Current ◽  
Phytoplankton Productivity ◽  
California Current System ◽  
Instrumental Records ◽  
The Impact

<p>Although most simulation models published have concluded that coastal upwelling will intensify in three of the most productive marine ecosystems of the world, the results seem contradictory for the California Current System (CCS). These contradictory results may be due to the fact that instrumental records are too short to yield reliable predictions. Because of this, we opted to test this hypothesis by studying the sedimentary record of Soledad basin, in Baja California, Mexico, using geochemical proxies to reconstruct at ultra-high resolution the history of productivity and sea surface temperature during the last two millennia, with particular emphasis on the Anthropocene. Our results indicate that SST (alkenones and TEX-86) do not show a cooling trend during the Anthropocene, but rather multidecadal cycles related to PDO. Likewise, primary productivity organic biomarkers [i.e., alkenone concentration (C37 Total) as a proxy for phytoplankton productivity, etc] show an increasing trend that started 2000 years ago with prominent multidecadal cycles, but without any observable trend taking place during the Anthropocene. An interesting feature of the organic matter record is the increasing amplitude of the cycles towards the present, starting 2000 years ago. Primary productivity is probably controlled by large scale mesoscale eddies developing at the southern Baja California margin.</p>

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