5/19/2015  |   15:30 - 15:45   |  103DE

DIEL VARIABILITY IN PREY CAPTURE BY TWO SPECIES OF UTRICULARIA (LENTIBULARIACEAE) FROM SOUTH CAROLINA, USA Bladderworts (Lentibulariaceae: Utricularia) are fascinating carnivorous plants that frequently live in nutrient-poor environments. These plants are famous for the bladder-like traps on their stems, which create a vacuum and suck prey into the bladder when a trigger hair is bumped. I found two abundant species of Utricularia in wilderness areas within the Francis Marion National Forest in South Carolina, and I collected a sample every three hours from 0600 to 2400 on July 7-9, 2014. Bladders were dissected in the lab, from which recovered animals were identified and counted. Number of prey items ranged from 0.20-0.49/bladder, and a diel shift was observed in prey capture intensity in both species, with more prey captured during the day than at night. Peak prey capture occurred three hours earlier in U. gibba than in U. inflata, although both species appeared to be utilizing the same prey base, providing a possible example of ecosystem partitioning between the two species.

Grant DeJong (Primary Presenter/Author), Pensacola Christian College, gdejong@geiconsultants.com;

5/19/2015  |   15:45 - 16:00   |  103DE

PREDATION STRUCTURED ODONATA ASSEMBLAGES IN FISHLESS, SALMONID, AND CENTRARCHID PONDS IN MAINE Predation is recognized as a strong determinant of lentic invertebrate community structure, and considerable attention has been focused on effects of insectivorous fish species on Odonata assemblages. Our goal was to clarify the effects of different fish predators on the local distribution of damselflies (Zygoptera) and dragonflies (Anisoptera). We surveyed odonate assemblages in ponds in eastern Maine with three different fish predation regimes - fishless, salmonid-dominated or centrarchid-dominated. Three belt transects were established in littoral macrophyte zones at each study pond, and adult Zygoptera and larval Anisoptera were sampled in each transect during two survey periods. Environmental characteristics were similar between fishless and fish-containing ponds, although fishless ponds were slightly more acidic. Odonate species richness and total abundance were similar among the three pond types, but significant differences in species assemblages existed among pond types for both suborders. Zygoptera assemblages differed between fishless and fish-containing ponds, while being similar between salmonid and centrarchid ponds. Anisoptera assemblages differed among the three pond types. These results have implications for conservation of Odonata in aquatic systems managed for recreational fishing.

Emily Schilling (Primary Presenter/Author), Augsburg University, schillin@augsburg.edu;

5/19/2015  |   16:00 - 16:15   |  103DE

USING BIOMASS SPECTRA TO QUANTIFY FISH AND MACROINVERTEBRATE COMMUNITY STRUCTURE IN SOUTHERN WEST VIRGINIA STREAMS Quarterly fish and macroinvertebrate data, including population abundance and biomass, were collected in three wadeable, southern West Virginia streams. Study objectives were to characterize the natural history of a historically understudied region and to test the applicability of biomass spectrum analysis—the negative relationship between average individual biomass within binned mass categories and the total standing stock biomass of a given size interval—in small streams. Biomass spectra have been rigorously documented in lake and marine ecosystems but are rarely examined in lotic systems. We estimated fish abundances using 3-pass electrofishing depletion surveys, with all fishes identified and weighed. Macroinvertebrates were collected from riffles and runs with a Hess Sampler, preserved and returned to the lab for identification, and published length-mass regressions used to estimate individual biomass. Preliminary analyses of combined fish and macroinvertebrate data suggest that biomass spectra in our study streams are nearly identical to published lake spectra, with characteristic slopes of approximately -1.0. This suggests that the distribution of individual and total biomass in lotic and lentic ecosystems may be subject to similar regulatory mechanisms.

Andrew Kirk (Primary Presenter/Author), Virginia Commonwealth University, andrew.kirk@deq.virginia.gov;


Daniel McGarvey (Co-Presenter/Co-Author), Center for Environmental Studies, Virginia Commonwealth University, djmcgarvey@vcu.edu;

5/19/2015  |   16:15 - 16:30   |  103DE

SHOULD THEY STAY OR SHOULD THEY GO? THE INTERACTIVE INFLUENCE OF HABITAT COMPLEXITY AND CONNECTIVITY ON PREY CONSUMPTION AND COMPETITION IN DRAGONFLY LARVAE AND FISH. Structural habitat complexity (SHC) and patch connectivity (PC) effect predator-prey interactions and exert a strong influence on community structure/dynamics in terrestrial and aquatic ecosystems. Although these factors vary simultaneously in most systems, their interactive effects are poorly understood. Using pond mesocosms, we manipulated plant density (SHC: low, high) and between patch distance (PC: short, long) in a full factorial design to test their interactive effect on predation by larval dragonflies and fish. In the low/short treatment Anax junius consumed more amphipods (62%±8.7) compared to the low/long treatment (36%±4.8;p=0.05). Lepomis spp. consumed more larval damselflies in the high/short treatment (72%±4.9) compared to the low/short treatment (46%±8.1;p<0.01). Interference competition occurred at low SHC for snail consumption (23%±3.4 actual vs 47%±4.3 expected;p<0.01). Results suggest SHC and PC interactively influence predator foraging behavior depending on the predator/prey combination, but interspecific competition between these predators is only influenced by SHC. This study indicates that SHC and PC should be considered in combination because their influence is synergistic in many aquatic communities, altering predator foraging behavior and changing predator/prey dynamics in complex ways.

Kristopher Pitcher (Primary Presenter/Author), University of South Dakota, Kristopher.Pitcher@coyotes.usd.edu;


Daniel Soluk (Co-Presenter/Co-Author), University of South Dakota, daniel.soluk@usd.edu ;