1 / 23

Influence of mesoscale eddies on ichthyoplankton assemblages in the Gulf of Alaska

Influence of mesoscale eddies on ichthyoplankton assemblages in the Gulf of Alaska. Elizabeth C. Atwood 1 , John K. Horne 2 , Janet T. Duffy-Anderson 3 , Carol Ladd 4 Speaker, Quantitative Ecology and Resource Management, University of Washington, Seattle, eatwood@u.washington.edu

crevan
Download Presentation

Influence of mesoscale eddies on ichthyoplankton assemblages in the Gulf of Alaska

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Influence of mesoscale eddies on ichthyoplankton assemblages in the Gulf of Alaska Elizabeth C. Atwood1, John K. Horne2, Janet T. Duffy-Anderson3, Carol Ladd4 Speaker, Quantitative Ecology and Resource Management, University of Washington, Seattle, eatwood@u.washington.edu School of Aquatic and Fishery Sciences, University of Washington, Seattle  Resource Assessment and Conservation Engineering, NOAA/NMFS , Seattle Pacific Marine Environmental Laboratory, NOAA, Seattle

  2. Larval dispersal • Ichthyoplankton dispersal • Influences species growth, survival and recruitment success • Oceanographic conditions • Impact larval dispersal trajectories Beneficial Detrimental Inappropriate slope habitat Nursery shelf habitat

  3. Mesoscale eddies in the GOA • Coastal origin, shelf-break eddies (cir. 100 km diameter) • High cross-shelf water exchange • Influence nutrient, chlorophyll, and zooplankton • Eddies: Haida, Sitka, and Yakutat Log(Chl) 4.0 3.2 2.4 1.6 0.8 Chlorophyll data from Giovanni, http://disc.sci.gsfc.nasa.gov/giovanni/

  4. Mesoscale eddies in the GOA • Coastal origin, shelf-break eddies (cir. 100 km diameter) • High cross-shelf water exchange • Influence nutrient, chlorophyll, and zooplankton • Eddies: Haida, Sitka, and Yakutat Log(Chl) 4.0 3.2 2.4 1.6 Yakutat 0.8 Sitka Haida Chlorophyll data from Giovanni, http://disc.sci.gsfc.nasa.gov/giovanni/

  5. Study objectives • Identify assemblage patterns within and between eddies • Evidence for eddy entrainment of semi-passive ichthyoplankton

  6. GOA eddy data collection Yakutat • 2005 data collection • Cruise in April/ May • Ladd et al., 2009 • Biological & physical data • Bongo: eggs, larvae, and juvenile density • CTD and bottle: Sitka Haida • a suite of oceanographic variables • Mixed Layer Depth (MLD) • Satellite sea surface height (SLA), measure of eddy location 333 μm mesh 60 cm diameter

  7. assemblage patterns Hierarchical clustering ofspecies matrix Yakutat Sitka Haida Group: 1 45 2 3

  8. assemblage patterns Hierarchical clustering ofspecies matrix • Haida eddy group (2) • Coastal group (3) • Mixed Sitka and Yakutat groups (4 and 5) Yakutat Sitka Haida Group: 1 45 23

  9. assemblage patterns Comparing clustersspecies matrix Low Low/ Medium Medium Heatmap analysis High/ Medium High Species Stations

  10. assemblage patterns Comparing clustersspecies matrix Low Low/ Medium Medium Heatmap analysis High/ Medium High Species Group: Edge S/ Y int.S/ Y int. Haida Coastal Stations

  11. assemblage patterns Comparing clustersspecies matrix Low Low/ Medium Medium Heatmap analysis • Southern species group High/ Medium High Species Blue lanternfish California flashlightfish Ragfish Myctophidae Group: Edge S/ Y int.S/ Y int. Haida Coastal Stations

  12. assemblage patterns Comparing clustersspecies matrix Low Low/ Medium Medium Heatmap analysis • Southern species group • Abundant species group >75% overall catch High/ Medium High Northern lampfish Rockfish Pacific blacksmelt Northern flashlightfish Arrowtooth flounder Sablefish Species Group: Edge S/ Y int.S/ Y int. Haida Coastal Stations

  13. assemblage patterns Hierarchical clusteringoceanographic matrix • Variables • (above MLD): • bottom depth, temp, salinity, density (σT) , chlorophyll, oxygen, PO4, SiO4, NO3, • SLA Group: 5 4 2 1 6 3

  14. assemblage patterns Comparing clusters species to oceanographic Low Low/ Medium Heatmap analysis Medium High/ Medium High Species Group: S int. S int.EdgeOutside Y cen. H/ S cen. Stations

  15. assemblage patterns Comparing clusters species to oceanographic Low Low/ Medium Heatmap analysis • Abundant species group concentrated in center stations Medium High/ Medium High Northern lampfish Rockfish Pacific blacksmelt Northern flashlightfish Arrowtooth flounder Sablefish Species Group: S int. S int.EdgeOutside Y cen. H/ S cen. Stations

  16. assemblage patterns Observed patterns • Species matrix clustering • Latitudinal gradient suggested by presence of southern species group • Presence of an abundant species group • Oceanographic matrix clustering • Clean clustering into center, edge, and outside eddy groups • Connections between species and ocean matrices • Concentration of abundant species group in the center eddy stations

  17. eddy entrainment Ichthyoplankton entrainment • Diversity measures Species richness Species turnover for each haul between consecutive hauls • Regression analysis • Larval response to eddy position Species richness βW βI βR

  18. eddy entrainment Ichthyoplankton entrainment • Diversity measures Species richness Species turnover for each haul between consecutive hauls • Regression analysis • Larval response to eddy position Species richness βW βI βR Peaks within an eddy Peaks along eddy edge

  19. eddy entrainment Regression analyses Transformed density by log(distance) • (density)1/4 = 4.90 - 0.23*log(dist) + ε • r2 = 0.118 • p = 0.1176 • Density • Abundant species group • Simple linear regression • Negative correlation, but not significant • Diversity • Species richness • General Linear Model (gamma family) • Negative correlation and significant (density)1/4 Log(distance) Diversity by log(distance) • (diversity)1/4 = • 1 • (0.07 - 0.02*log(dist) + ε) • AIC = 74.801 • p = 0.00025 Species richness Log(distance)

  20. eddy entrainment Regression analyses Transformed density by log(distance) • (density)1/4 = 4.90 - 0.23*log(dist) + ε • r2 = 0.118 • p = 0.1176 • Density • Abundant species group • Simple linear regression • Negative correlation, but not significant • Diversity • Species richness • General Linear Model (gamma family) • Negative correlation and significant (density)1/4 Log(distance) Diversity by log(distance) • (diversity)1/4 = • 1 • (0.07 - 0.02*log(dist) + ε) • AIC = 74.801 • p = 0.00025 Species richness Log(distance)

  21. eddy entrainment Regression analyses Transformed density by log(distance) • (density)1/4 = 4.90 - 0.23*log(dist) + ε • r2 = 0.118 • p = 0.1176 • Density • Abundant species group • Simple linear regression • Negative correlation, but not significant • Diversity • Species richness • General Linear Model (gamma family) • Negative correlation and significant (density)1/4 Log(distance) Diversity by log(distance) • (diversity)1/4 = • 1 • (0.07 - 0.02*log(dist) + ε) • AIC = 74.801 • p = 0.00025 Species richness Log(distance)

  22. Evidence for entrainment • Assemblage patterns: clustering • Latitudinal species gradient • Eddy center concentration of abundant species group • Eddy entrainment: Regression (density, diversity) • Negative correlation to distance from eddy center • Potential vector for larval dispersal • Beneficial or detrimental

  23. Thank you to my co-authors: John K. Horne, Janet T. Duffy-Anderson, and Carol Ladd Work kindly funded by NPRB and AFSC Thanks to the crew of the R/V Thompson G. Thompson Questions?

More Related