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  1. The Effects of Spatial and Temporal Environmental Variability on the Distribution and Population Dynamics of the Sea Scallop (Placopecten magellanicus) Ph.D. Dissertation Proposal by Grant Law a Advisor: John Quinlan a Committee Members: Jim Miller a Dave Bushek a John Manderson b Hal Batchelder c a) Rutgers Institute of Marine & Coastal Sciences b) NOAA’s J.J. Howard Marine Sciences Laboratory c) Oregon State University Funded by the Rutgers University - NOAA Cooperative Marine Education & Research Program

  2. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  3. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  4. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  5. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  6. Sediment types Productivity Frontal systems Cold pool Gyres Flow regimes Dissolved oxygen Community composition Stratification Temperatures Tides Internal waves Etcetera . . . Habitat Variability The N-Dimensional Hypervolume

  7. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  8. Emergent Distributions • Spatial factors • Static factors • Dynamic factors • Size-class specific impacts

  9. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  10. Why Disperse Larvae? • Traditional rationalization (seeds) • Colonize newly available habitat • Avoid competition with parents • Marine specific rationalization (larvae) • Avoid specialized benthic predators • Weaken density of predator-field • Exploit abundant high-quality food resource

  11. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  12. Colonization • Ephemeral habitats/aggregations • Large numbers of larvae • Widely dispersed larvae • Planktotrophic larvae • High growth rates • High rates of resource utilization

  13. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  14. Competition • Adult-heavy demographics • Consistent habitats/aggregations • Juveniles and adults utilizing same limiting resource • Ambient limiting resource maintained at low availabilities

  15. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  16. Predation Concerns • Predator encounter rate differences between 2D and 3D habitats. • Preponderance of the generalist strategy among predators of plankton

  17. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  18. Food Resources • Productivity • Concentrating mechanisms • Thin-layer dynamics

  19. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  20. Impacts of Dispersal Single, patchy Population (open) Metapopulation (structured connectance) Separate (closed) High Low Population Connectivity Modified from Harrison and Taylor (1997)

  21. Impacts of Dispersal • Genetic similarity between distant sub-populations is high with small amounts of connectance • Interactions between larval behavior and variability of circulation patterns may play a significant role in connectivity, and therefore local persistence

  22. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  23. Transport patterns

  24. Transport patterns

  25. 40m drifters 10m drifters 81 13 115 28 12 1 6 3 2 0 61 Offshore total 61 Offshore total 10 1 13 38 2 4 13 1 15 2 1 0 23 4

  26. Transport patterns

  27. Transport patterns • Vertical migration • Refuge from predation • Targeting areas of high food densities • Mechanism for directional transport

  28. Transport patterns Timing of vertical migration

  29. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  30. Density & Reproductive Success • For organisms with broadcast spawning, density likely effects fertilization success • For organisms with low movement rates or limited foraging ranges (such as territorial species), density impacts the availability of mates

  31. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • Habitat variability • Emergent distributions • Why disperse larvae? • Colonization • Competition • Predation concerns • Food resources • Impacts of dispersal • Transport patterns • Density & reproductive success • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  32. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  33. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  34. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Assumptions of resource harvesting • Demographic effects and consequences • Spatial-management • Ecological vs. evolutionary time scales • Metapopulation approach • Important questions/hypotheses • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  35. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Assumptions of resource harvesting • Demographic effects and consequences • Spatial-management • Ecological vs. evolutionary time scales • Metapopulation approach • Important questions/hypotheses • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  36. Assumptions of Resource Harvesting • Applicability of the agricultural model to marine resources • Fast growing, widely dispersing species • Consistency of recruitment • Demographic considerations • Targeting of demographic subgroups • Maximum sustainable yield (MSY) concept

  37. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Assumptions of resource harvesting • Demographic effects and consequences • Spatial-management • Ecological vs. evolutionary time scales • Metapopulation approach • Important questions/hypotheses • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  38. Demographic Effects & Consequences • Sensitivity to environmental extremes • Sensitivity to predation • Differences in fecundity between size classes

  39. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Assumptions of resource harvesting • Demographic effects and consequences • Spatial-management • Ecological vs. evolutionary time scales • Metapopulation approach • Important questions/hypotheses • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  40. Spatial Management • Fishery Closures • Marine protected areas • Rotational harvesting • Imposes spatial pattern of fishery-related mortality • Changes in connectance may have unexpected consequences

  41. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Assumptions of resource harvesting • Demographic effects and consequences • Spatial-management • Ecological vs. evolutionary time scales • Metapopulation approach • Important questions/hypotheses • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  42. Ecological Vs. Evolutionary Time Scales • Connectance occurs at a time scale similar to that of reproductive cycles • Any evaluation of the impacts of variable connectance should be carried out at these scales • A question of ‘local persistence’ • Interplay of vital rate potentials and demographic structure

  43. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Assumptions of resource harvesting • Demographic effects and consequences • Spatial-management • Ecological vs. evolutionary time scales • Metapopulation approach • Important questions/hypotheses • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  44. Metapopulation Approach • Considers a population to be made up of multiple smaller populations each having some degree of connectance to a subset of the others - through adult migration or transfer of propagules • Demonstrates how the effects of local events can propagate throughout the entire population • These pulsed effects may interact with each other at the sub-population level, producing episodic local population booms or crashes

  45. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Assumptions of resource harvesting • Demographic effects and consequences • Spatial-management • Ecological vs. evolutionary time scales • Metapopulation approach • Important questions/hypotheses • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  46. How well connected are closed areas with other areas -- both closed and open -- and does this connectivity change with population structure or physical forcing? Are all closed areas equally valuable? Does a given area always operate as a source or sink region? How often is a given area dependent on ingressing recruits? Under which conditions is a given area self-seeding and how often are those conditions present? Are there regions of the coast that are particularly robust in terms of self seeding and which also act frequently as a source for remote areas? Is there an optimal spawning stock biomass and size structure and is it region dependent? Is it possible to create undesirable spatial structure in the population through management action? Important Questions/Hypotheses

  47. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  48. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • The basic approach • Initial Results • What's next...

  49. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • Life history • Management history • The basic approach • Initial Results • What's next...

  50. Sea Scallops and Environmental Variability • Spatial population dynamics in the coastal ocean • The fisheries-imposed spatial structure problem • Sea scallops as an excellent case study • Life history • Management history • The basic approach • Initial Results • What's next...