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Some Background Food For Thought: Climate Change, Hydrodynamics and Marine Invertebrate Larvae: Implications for MPA

The Sea in Motion. Currents - wind direction wind strength solar heating water density ; different densities cause different currentsTidal Currents

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Some Background Food For Thought: Climate Change, Hydrodynamics and Marine Invertebrate Larvae: Implications for MPA

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    1. Some Background Food For Thought: Climate Change, Hydrodynamics and Marine Invertebrate Larvae: Implications for MPAs Nancy Deschu, November 28, 2007

    2. The Sea in Motion Currents - wind direction + wind strength + solar heating + water density ; different densities cause different currents Tidal Currents – directional flow from tidal action Eddies – rotary currents that may be small (< 1km) or very large (>100 km), may be short- or long-lived Upwellings - vertical water movement upwards Downwellings – vertical water movement downwards Nancy Deschu, November 28, 2007 after Gross, 1995 and Thurman and Trujillo, 2004 3-6 km per day average3-6 km per day average

    3. The Sea in Motion (continued) Clines- boundaries between zones; salinity, temperature, density Waves – wind, gravitational pull, undersea earthquakes and slides Turbulence – disturbance to normal flows due to winds, obstacles Global Conveyor Belt - worldwide circulation pattern of seawater due to temperature and salinity gradients Oscillations – periodic see-saw changes in atmospheric conditions which affect ocean temperature (e.g. ENSO)

    4. Marine Invertebrate Larvae Movement Marine invertebrate larvae do not travel as passive particles Invertebrate larvae swimming speeds are much slower than coastal currents so larvae have little control on their horizontal movement Horizontal dispersal is controlled mainly by migrating vertically through the water column Nearly all marine invertebrate larvae require leaving the spawning grounds and “returning” to suitable settlement sites

    5. Advantages of planktonic development: from The Invertebrates, Barnes, Calow and Olive, 2nd ed., 1993 Colonization of new habitats Expanse of geographic range Exposure of diverse offspring to diverse habitats Avoidance of possible local habitat failure Avoidance of local and sib-competition Exploitation of temporary phytoplankton-bloom food sources

    6. Climate Change Effects ? Hydrodynamic processes ? influence on marine invertebrate larvae A Few Scenarios to Think About….. Extreme winds ? changes in waves, currents, surge, water velocity, upwelling intensity? Storm frequency, storm intensity, storm surge behavior? turbulence and mixing? Sea- surface temperature ?warmer surface water; water density changes? Water density changes ? changes in horizontal and vertical flows? Cline shifts ? changing horizontal boundaries, barriers made and broken? Nutrient concentrations ? shifts in locations and concentration of nutrients?

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