Jeff Wesner

Ph.D candidate -zoology

university of oklahoma and oklahoma biological station

In my dissertation research I study trophic connections between stream and riparian food webs.  I am interested in how fish regulate this connection through predation on organisms with complex life-histories, which transition from aquatic to terrestrial habitats through their development.

Current projects

ALL PREY ARE NOT THE SAME: ADULT AQUATIC INSECTS IN TERRESTRIAL FOOD WEBS

Many species of insects are aquatic as larvae and terrestrial as adults.  When they emerge as adults from aquatic habitats, they elevate prey abundance for terrestrial consumers, linking aquatic and terrestrial food webs.  However, unlike most fully terrestrial insects, many aquatic insects do not feed as adults.  During periods of peak aquatic insect emergence, insect assemblages along streams therefore have different trophic structures than assemblages dominated by fully terrestrial insects (right).  Different trophic structures means that consumption of insect prey assemblages composed mostly of adult aquatic insects may have different impacts in terrestrial food webs than consumption of fully terrestrial insect assemblages

EAT LOCALLY, IMPACT GLOBALLY: FISH PREDATION ALTERS THE MAGNITUDE AND TROPHIC STRUCTURE OF ADULT AQUATIC INSECT ASSEMBLAGES

I use a combination of mesocosm and natural stream experiments to examine how predation regimes in aquatic habitats alter prey assemblages in terrestrial habitats.  Results to date indicate that fish predation reduces biomass of emerging aquatic insects by, limiting energy available to terrestrial consumers.  In addition, the trophic structure of adult aquatic insect assemblages is different when fish are present - fish reduce predatory dragonflies disproportionately to other insect prey, thereby reducing emerging predator biomass.

NORTHERN INVASION: ECOLOGICAL DIFFERENCES BETWEEN NORTHERN AND SOUTHERN STRAIN BROOK TROUT IN SOUTHERN APPALACHIA 

Collaborators: Dr. Thomas Martin - Western Carolina University; Wes Cornelison - Eastern Band of Cherokee Indians, Office of Environment and Natural Resources; Dr. Peter Galbreath - Columbia River Inter-Tribal Fish Commission; Chris Dankmeyer - Bristol Bay Area Health Corporation

Stocked brook trout in southern Appalachia are derived from northern North American streams, and are genetically distinct from native southern Appalachian brook trout.  Through a series of lab and natural experiments, we’ve tested for ecological differences between introduced northern strain brook trout and native southern brook trout.  Northern brook trout readily spawn with southern brook trout, potentially disrupting thousands of years of evolved adaptations in southern strain brook trout to the local environment.  Our research suggests that aggression and tolerance to harsh conditions is stronger in northern strain brook trout, likely a remnant of artificial selection in northern strain brook trout, which have maintained wild-breeding populations for nearly 50 years.  This research suggests that in addition to genetic introgression, aggressive interactions between these strains of brook trout may speed the decline of native brook trout in southern Appalachia.

Stream mesocosms at UOBS

OKLAHOMA FISH DISTRIBUTIONS

Collaborator: Dr. William Matthews - University of Oklahoma

We are using fish species range limits and broad scale environmental data in Oklahoma to determine what factors limit species distributions.

Brier Creek, OK with emergence traps

Oconaluftee River, NC

Brier Creek, OK with bare emergence traps