1. Mortality Study GCRL Marine Animal Behavior 2018

2. Predation: The Struggle is Real!!
Direct vs. indirect effects of predation
Risk effects = “prey alter their behavior in response to predators, and these responses carry costs”
Risk effects can have a greater impact on survival than direct effects

3. Pathways by which predation can affect the population dynamics of prey
Restricted
View
Creel and Christianson 2008

4. Pathways by which predation can affect the population dynamics of prey
Whole Picture View illustrating the importance of risk effects
Creel and Christianson 2008

5. Using Mortality to Study Predation
Mortality can be due to natural death, environmental causes, or predation pressure (by natural predators or humans)
For our mortality study we will focus on natural predation pressure and how environment can play into prey susceptibility

6. General Plan for our Study
Collect grass shrimp from the GCRL marsh waters
Tether shrimp (explained in detail in next slide)
Tie shrimp to stakes in vegetated and non vegetated zones
Record the survival or death of each shrimp for a period of time

7. Step 1: How to tether Thread needle with fine nylon thread
Pierce the shrimp with the threaded needle horizontally through the dorsal carapace
(MAKE SURE TO AVOID VITAL ORGANS)
Tie ends of thread together to form a circle
Place each shrimp in a separate container to avoid tangling

8. Tethering

10. Step 2: Shrimp Placement
Outside at each zone (vegetated and non vegetated), take physical data (GPS, salinity, weather, etc.)
Tie 30 cm of light monofilament line halfway up metal flag and attach to shrimp’s harness
Do this for each shrimp making sure there is at least 1 meter between each flag

11. 1 m apart
Check every 5 minutes for 30 minutes
30 cm

12. Step 3: Monitoring Record time of placement
Monitor every 5 minutes for up to 30 minutes (record presence or absence of organism)
Each group should end up with data for 10 shrimp total (5 in vegetated and 5 in non vegetated zone)

13. GRASS SHRIMP MORTALITY STUDY
Transect Location:
Transect 1
Transect 2
Time
Shrimp 1
Shrimp 2
Shrimp 3
Shrimp 4
Shrimp 5 5 10 15 20 25 30