Presentation on theme: "The Importance of Pelagic Processes in determining Habitat in the Sea SeaScape Meeting Sandy Hook March 2, 2012 Donald B. Olson With major input from Jerry."— Presentation transcript:
The Importance of Pelagic Processes in determining Habitat in the Sea SeaScape Meeting Sandy Hook March 2, 2012 Donald B. Olson With major input from Jerry Ault, Ashley McCrea-Strub, Jing-Gang Luo, and William Harford
Regional Oceanography Bathymetry & CurrentsSea Surface Temperature 1 June 2011 Bottom topography and SST
Retrograde fronts: Density surfaces are perpendicular to the bottom topography Examples: Mid- Atlantic Bight Prograde fronts: Density surfaces parallel to bottom topography. Examples: Gulf Stream along U.S. coast or Kuroshio off China See Mooers et al or Olson 2001
Hudson River Plume Front
Ecosystem organization and fronts: Olson (2006)
Behavioral concentration in fronts under photo- or geo-taxis. (Olson and Backus, 1985, Olson, 2001, 2007)
Drifter trajectories on Georges Bank
Frontal Sweeping of Fish: Olson (2007)
Small boney fish. Oily High protein Detrital diet is rich in terrestrial nutrients
Americas First and Foremost Fishery: Menhaden or Mossbunker Early visitors to America came for cod; but the early colonists were not fishermen per see. Capt. John Smith noted on his first trip to Virginia that a small fish formed massive shoals in the shallow bays. Squanto (Tisquantum) taught the Pilgrims to place these small fish in mounds of corn to act as fertilizer.
The Menhaden Industry Early Long Island and New England fishery involved groups of farmers covering their fields with fish. In 1850s this gave way to industrial trying and processing oil and meal separately. Meal becomes easily shipped fertilizer and later animal feed. Oil becomes prime replacement for whale oil following the fall of the whale fishery after the early 1860s.
Conflicts with other resources:
Other species that cross habitats:
Tracing large scale flows using salinity and oxygen isotopes. The water entering high latitudes is lighter, has less O18 and more O16, since the latter evaporates more easily.
Drowned river valleys: Also partially mixed estuaries except at high flow. Shallow well mixed systems Conditions in an estuary and the nature of drainage basins.
What factors determine the maximum flux, Qr, that a linear riverine plume can take? What happens if this flux is exceeded?
A succession of river plumes Gulf Stream
Shortfin mako - Bluefish Interactions in the Western North Atlantic Ocean A large fraction (>80%) of mako diet consists of bluefish during part of the year; Food web model developed using Ecopath with Ecosim; Emphasis on indirect effects of fishing. Shortfin makoBluefish Fishery Indirect Effects William Harford
Multispecies Yield Surfaces Resource-driven control by bluefish was strongly evident; Mako fishery had little effect on bluefish (right), whereas bluefish fishery had notable effect on mako (left); Suggestive of competition for shared bluefish prey between mako & fisheries.
Model spatial grid resolution: 5.5 km x 5.0 km in south 5.5 km x 3.8 km in north < 3000 m; cells Atlantic Coast Ecosystem Simulation Model
Atlantic Coast Ecosystem Simulation (ACES) Model
Chlorophyll aSea Surface Temperature Small prey (Spring) < 200 mm Small prey (Fall) Prey Abundance
Factors affecting fish “spatial growth rate potential” components of “essential habitat”. August Age 0 Menhaden August Age 4 Menhaden (X,Y) Bluefish October 1 Transport and Movements of Predator & Prey April 15
ACES Model simulations Menhaden Biomass Bluefish Biomass
Warm core ring: Age 2 mos
Modeling Schooling with turbulence: (Flierl et al., 1999)
Spatial Ecosystem Models to Assess Multispecies Fisheries Risks from Exploitation and Environmental Changes
What are the effects of schooling affinities? Bakun’s Red fish/Blue fish hypothesis: Obligations to remain in schools shift fish populations towards different geographic locations based on metapopulation density within schools. Selection and genetics? The MacCall hypothesis: Fish make use of their ability to migrate as schools to exploit changes in mesoscale habitat linked to larger scale climate variations.
Simple Conceptual Model N1 N2N3 F K Olson, Cosner, Cantrell and Hastings (2005)
The process of predation: Predator/Prey encounters Handling times (satiation included) Explicit inclusion of schooling dynamics (Cosner et al., 1999)
Fisheries yield and yield vs costs N₂N₂ N₁N₁ Cost N₂N₂ Olson et al. (In prep)
Summary Fisheries habitat is at the highest level set by the physical factors: Climatological postions of front and circulations and their dynamics; seasonal progression of S, T,… Trophic interactions between species and the adaptation to each other and the environment. The use of habitat by fishermen is a crucial factor in terms of understanding fisheries.