1. Triops Interactions: Drivers and feedbacks in
ephemeral pond communities
Mitch Van Dyke and Brian J. O’Neill
Predation
Feedback
Competition
Triops
Invertebrate
Community
Triops-Community
Feedback System
Environment
How are Triops competing
with each other?
Higher Triops density resulted in smaller size
Larger Triops produced more eggs
Size may be limited by food availability
y =  15.44x
R2 = 90.44%
P-value = 0.00
y =  0.3287x
R2 = 22.20%
Triops (Crustacea: Notostraca)
Description
Genus of brachiopods that lay drought-resistant eggs1
Feed on detritus, algae, and small invertebrates2
Found in temporary waterbodies3
Often reach high densities3
Ecological Importance
Bioturbation: sifting behavior that agitates soil altering the environment
Competition with other detritivores4
Predation after their diet shift4
Wet Ephemeral Pond
Dry Ephemeral Pond
Methods
Laboratory Microcosms
Tubs filled with ephemeral pond soil and water
Set up and torn down in 2 week cycles to simulate 2 week hydroperiods
7-9 tubs per sampling period
14 sampling periods completed so far
Measurement
Invertebrates counted 3 times per hydroperiod using a 4x4inch viewing square for 2 minutes
All invertebrates collected and preserved after 3 weeks
Triops will be sent in for stable isotope analysis after all samples are collected
How does the community
feed back on Triops?
Triops were smaller with higher fairy shrimp density on day 11
Triops growth limited by interspecific competition early in the hydroperiod
Triops size was highly variable with no fairy shrimp
Fairy Shrimp
y =  0.3122x
R2 = 35.73%
P-value = 0.00
The scientific community knows little about Triops:
General Diets
Diet Shifts
Community interactions2
Our goal is to define how Triops fit into ephemeral community structure by examining:
4) Triops impact on invertebrate community
3) Invertebrate community impact on Triops
2) Intraspecific competition among Triops
1) Environment affects on Triops
Our Study
How are Triops affecting
the community?
Ostracod density was lower when Triops density was high
Triops predation controls prey population densities
Ostracods
How are Triops affected
by the environment?
Triops grew larger when temperatures were higher
Triops exhibited increased fecundity with higher temperatures on day 11
Higher temperatures speed body development and egg production
y =  0.2508x
R2 = 9.04%
P-value = 0.00
y =  0.1825x
R2 = 15.68%
y =  6.652x
R2 = 95.95%
y =  0.0409x
R2 = .35%
P-value = 0.442
References
1Sim, L. L., Davis, J. A., Strehlow, K., McGuire, M., Trayler, K. M., Wild, S., & O’Connor, J. (2013). The influence of changing hydroregime on the invertebrate
communities of temporary seasonal wetlands. Freshwater Science, 32(1),
2Boix, D., Sala, J., Gascon, S., & Brucet, S. (2006). Predation in a temporary pond with special attention to the trophic role of Triops cancriformis (Crustacea:
Branchiopoda: Notostraca). Hydrobiologia, 571(1),
3Williams, D. D. (1996). Environmental constraints in temporary fresh waters and their consequences for the insect fauna. Journal of the North American
Benthological Society, 15(4),
4Yee, S. H., Willig, M. R., & Moorhead, D. L. (2005). Tadpole shrimp structure macroinvertebrate communities in playa lake microcosms. Hydrobiologia, 541(1),
Acknowledgements
University of Wisconsin – Whitewater Biology Department, University of Wisconsin – Whitewater Undergraduate Research Program