Advancement2 2
Download as PPTX, PDF1 like195 views
This document outlines a proposed study examining the effects of increased temperature and changes to hydroperiod on California vernal pool communities. The study will use mesocosms to simulate vernal pools under different temperature and hydroperiod treatments. It is hypothesized that increased temperature and shorter/later hydroperiods will decrease macroinvertebrate and zooplankton diversity. The experimental design involves warming mesocosms and manipulating hydroperiod timing and duration. Communities will be sampled biweekly and analyzed to understand impacts of climate change on these temporary freshwater ecosystems.
Advancement2 2
- 1. Temperature and hydroregime effects on California vernal pool mesocosm communities Presented by Robin Shin Advancement to candidancy 12/7/2016
- 2. Outline 1. Climate change and temperature 2. Warming effects on ecosystem processes 3. Warming & freshwater ecosystems 4. Temporary aquatic ecosystems (hydroregime characteristics) 5. Warming effects on temporary aquatic communities 6. Thesis proposal - California vernal pools - hypotheses - methods & experimental design - sampling & timeline
- 3. Climate change & temperature • Increases in temperature will alter ecosystem structure and function at both global and local scales.
- 4. California • +1.1-2.0 °over past century • Maximum & minimum annual temperature increases. • +3.4-4.9 ° in air and water temperature by 2060-2069 (CADWR, 2015)
- 5. Climate change and ecosystem processes
- 6. Climate change and freshwater ecosystems • Freshwater diversity at higher risk than terrestrial systems • Insular habitats, anthropogenic exploitation, habitat fragmentation & pollution. • Permanent & temporary water bodies.
- 7. Temporary aquatic ecosystems • Dependent on annual temperature & hydroregime intervals. • Hydroregime: – Duration – Timing – Magnitude • Duration & timing important in structuring temporary aquatic communities. Mather Fields
- 8. Rock pools at Vasco Caves near Byron, Ca. A) Ephemeral playas Vernal pool located near Amherst, Massachusetts. Temporary wetlands Southern France
- 9. Temporary systems: Inundation duration & timing • Longer periods of inundation lead to higher diversity • Shorter lengths tend to be more frequently dominated by passive dispersers • Intra- & inter annual variability affect community composition Active disperser Passive disperser
- 10. Photoperiod (hrs) 9 12 15 Temperature (°F) (Red) 54° 65° 90° Jan. July Sept.Mar. May Month Dec. Timing of inundation covaries with photoperiod & temperature Temporary systems: Inundation duration & timing
- 11. Warming & temporary aquatic communities • Difficult to extrapolate across taxons & ecosystems. • Many studies species- specific (ie.Phytoplankton sp.) • Few warming studies done on temporary systems.
- 12. Temporary aquatic ecosystems • Few studies on warming & temporary systems. • Pyke(2005)- modeled hydrologic changes with predicted temperature increases. • Found: – Mid-Central Valley more responsive to change – Smaller, shallower pools more at risk – Changes in hydroregime may outweigh changes in temperature
- 13. Primary Producers Consumers Phytoplankton Daphnia sp. • Both declines & increases in phytoplankton diversity observed • Lab vs Field studies Warming • Higher growth & feeding rates vs. metabolic costs & competition Taxonomic shifts in size structure
- 14. Thesis proposal • Examine abiotic and biotic responses to experimental manipulations of water temperature and hydroregime (duration and timing). • Mesocosms to measure changes in aquatic community richness and density. • Conservation & management implications on what to expect of future climates.
- 15. Study system: California vernal pools • Impermeable layer of hardpan which prevents water from percolating through the soil. • Range: Southern Oregon to Northern Mexico • Relatively predator free environment during the aquatic phase • High rates of endemism
- 16. Federally threatened Vernal pool fairy shrimp-Brachinecta lynchi Federally endangered Vernal pool tadpole shrimp ( Lepidurus packardi) Seed shrimp, Ostracoda Cladocerans (Daphnia pulex) Predatory diving beetles, Hydrophilidae. Anisopteran larvae photo Mosquito larvae, Culicidae. Copepoda Ca. fairy shrimp. Linderiella occidentallis Passive dispersers Active dispersers
- 17. Hypotheses • H1: Macroinvertebrate & zooplankton diversity will be lower in warmed treatments • H2: Longer periods of inundation will result in a decrease in macroinvertebrate & zooplankton diversity • H3: Later inundation timing treatments will result in a decrease in macroinvertebrate & zooplankton diversity.
- 18. Methods • Twenty mesocosms (37.8 L; diameter= 0.6m, height=0.18m, area=0.28m²). • 3.0 cm of Ca. vernal pool soils to each • Electronic heaters (Aqueon 10 watt mini-heater). • HOBO Pendant temperature–light 8k waterproof data loggers (Onset Computer Corporation, Pocasset, Massachusetts.)
- 19. Experimental design • Warm & control long hydroperiod treatments (A.) • Warm & control short-late inundation treatments (B.) • Weeks 1- 10 of long hydroperiod treatments will constitute the warm & control short-early (C.) Figure 1. Experimental design A: warm (red) & control (blue) long hydroperiod (20 weeks) B: warm & control short-late hydroperiod (10 weeks) C: warm & control short-early (data weeks 1-10 of A)
- 20. Sampling • bi-weekly basis using a mesh aquarium net swept in a circular fashion for 15 seconds. • Individuals will be enumerated on a gridded tray and returned to the mesocosm. • water-quality characteristics (dissolved oxygen, turbidity, conductivity, nitrates & phosphates) will be conducted four times. January-May 2017: Collection of data. June-August 2017: Statistical analysis of data. September-December 2017: Write up and thesis defense.