Joel Trexler in a karst landscape of the Rocky Glades in Everglades National Park.  Deep solution holes like this one hold water and fish through the dry season.  Though such holes act as dry-season refuges today, it appears that most fish here in the wet season must disperse in from the Shark Slough.  Historical records raise indicate that these areas had more water before drainage began.  Perhaps these refuges were more important in the dynamics of aquatic communities back then.

Only expert throw trappers can smile when the water levels get high in the wet season!  Raul Urgeles and Erika Grumbach show how its done.

Jennifer Rehage gets ready to release a big lake chubsucker she caught while electrofishing.  Her recent study indicates that fish and macroinvertebrate biomass is relatively high at the edges of canals, but drops off over relatively short distances into the marsh.  Since radio tracking (and recreational fishing patterns) indicate that large predatory fish move into canals from marshes in the dry season, more study is needed on the influence of these two habitats on each other (a possible example of metacommunity dynamics).

Research Interests

Our lab focuses on two types of questions that are central to ecology and evolutionary biology. The first is related to budgets, trade-offs in allocating limited resources, and the genetic and/or ecological constraints that shape those trade-offs.  I have recently been working with Don DeAngelis on models of the evolution of complex reproductive adaptations in poeciliid fish  The second type of question involves the implications of spatial ecology and migration on community dynamics. This work involves testing concepts of metacommunity dynamics in the Everglades.
 
 
 

Since graduate school  I studied life history ecology and evolution of poeciliid fishes.  My latesst work in this area has been through collaborations with Don DeAngelis in exploring the conditions under which their complex reproductive adaptation may arise.  These graphs are from our most recent paper on this topic.  Trexler, J. C., and D. L. DeAngelis. 2003.  Resource allocation in offspring provisioning: an evaluation of the conditions favoring the evolution of matrotrophy.  American Naturalist 165:574-585
Cartoon of life cycle of poeciliid fish showing complex interaction of feeding and reproductive history on energy available for reproduction.	Our model predicts that spreading investment in offspring across gestation (matrotrophy) is only favored in high food (and stable food) environments.  Investment in eggs with the full store of energy needed to bring embryos to term (lecithotrophy) is the ancestral state.

We are also interested in applying the tools of ecology and evolutionary biology to environmental problems.  Connecting our research activities to applied problems strengthens our research program, both by keeping us focused on processes that are observed in field conditions and in preparing graduate students braodly for an uncertain professional environment of the future.

Population and community ecology provide a powerful basis for solving problems confronted by environmental management. One aspect of this in identifying targets of environmental management for use in assessment and evaluation of ecological restoration efforts.  A particular application of ecological and evolutionary theory that interests me is in setting goals and targets for enviromnental management in cases where historical data are few and where no good reference sites are available (see Trexler, J. C., W. F. Loftus, and J. Chick. 2003. Setting and monitoring restoration goals in the absence of historical data: The case of fishes in the Florida Everglades, pp 351-376. In D. Busch and J. C. Trexler. Monitoring Ecoregional Initiatives: Interdisciplinary Approaches for Determining Status and Trends of Ecosystems.  Island Press).

Over the past 10 years, I have become very interested in the challenges presented by management and restoration of the Florida Everglades. My interest in this massive public-works project has arisen partly because it seeks to preserve a spectacular ecosystem at my backdoor, but also because of the problems presented to biologists in proceeding with restoration. Some of our work in this area is described in the links listed below.  Many of the papers cited can be downloaded at my publications webpage.
 
 
 

Mesocosm dosing with SFWMD	Nutrient dosing in the Everglades. In our lab, we are asking how changing patterns of productivity affect community structure of aquatic animals.  We are working in both mesocosm studies (shown on the left; with the South Florida Water Management District) and in large flow-through flumes (with the Everglades National Park; see pictures below).    Gaiser, E. E., J. C. Trexler, J. H. Richards, D. L. Childers, D. Lee, A. L. Edwards, L. J. Scinto, K. Jayachandran, G. B. Noe, R. D. Jones.  2005. Exposure to above-ambient phosphorus causes ecosystem state change in the Everglades.  Journal of Environmental Quality 34: 717-723  Turner, A. M., J. C. Trexler, F. Jordan, S. J. Slack, P. Geddes, and W. Loftus. 1999. Targeting ecosystem features for conservation: Standing crops in the Florida Everglades.  Conservation Biology 13:898-911	Project Description Latest Annual Report Our first annual report Look below, to see a picture of our flumes in Everglades National Park
	Florida Coastal Everglades, Long-term Ecological Research Site (FCE-LTER). In our lab, we are asking how the controls of fish community and population dynamics change along the salinity and productivity gradients in the southern Everglades. One of our study sites in Taylor Slough is shown on the left. Trexler, J. C., W. F. Loftus, C. F. Jordan, J. Chick, K. L. Kandl, T. McElroy, R. M. Kobza, and O. L. Bass. 2001. Ecological scale and its implications for freshwater fishes in the Florida Everglades.  Pp. 153 – 181,  in  J. W. Porter and K. G. Porter (eds.) The Everglades, Florida Bay, and Coral Reefs of the Florida Keys: An Ecosystem Sourcebook. CRC.	FCE-LTER home page Poster describing our work
	Monitoring fish communities at the landscape scale. For over five years, we have been sampling fish communities quantitatively from 17 sites (55 plots) scattered over the southern Everglades, in collaboration with Everglades National Park biologists, who sample an additional 3 sites (9 plots). Our goal is to monitor fish community dynamics over time and document environmental relationships. We are particularly interested in quantifying relationships of fish communities to hydrological management, and time-lags in ecological response to manipulation of hydrology. We sample for small fish (<8cm std length) with a 1-m2 throw trap, shown to the left, and large fish (>8cm std length) with a boat-mounted electrofisher. A map of our study sites appears at the bottom of this webpage. Some of our latest findings: Trexler, J. C., W. F. Loftus, and S. Perry.  2005. Disturbance frequency and community structure in a twenty-five year intervention study. Oecologia, in press Ruetz, C. R., III, J. C. Trexler, F. Jordan, W. F. Loftus, and S. A. Perry.  2005. Population dynamics of wetland fishes: Spatiotemporal patterns shaped by hydrological disturbance?  Journal of Animal Ecology 74:322-332  Chick, J. H., C. R. Ruetz III, and J. C. Trexler.  2004.  Spatial scale and abundance patterns of large fish communities in freshwater marshes of the Florida Everglades.  Wetlands 24:652-664  Data are no better than the methods used to get them: Dorn, N. J., R. Urgelles, and J. C. Trexler.  2005. Evaluating active and passive sampling methods to quantify crayfish density in a freshwater marsh. Journal of the North American Benthological Society 24:346-356 Wolski, L. F., J. C. Trexler, E. B. Nelson, T. Philippi, and S. A. Perry.  2004. Assessing visitor impacts from long-term sampling of wetland communities in the Everglades.  Freshwater Biology 49:1381-1390  Chick, J. H., S. Coyne, and J. C. Trexler. 1999. Effectiveness of airboat electrofishing for sampling fishes in shallow vegetated habitats. North American Journal of Fisheries Management 19:957-967  Jordan, C. F., S. Coyne, and J. C. Trexler. 1997. Sampling fishes in heavily vegetated habitats: the effects of habitat structure on sampling characteristics of the 1-m2 throw trap. Transactions of the American Fisheries Society 126:1012-1020.  Turner, A., and J. C. Trexler. 1997. Sampling invertebrates from the Florida Everglades: a comparison of alternative methods. Journal of the North American Benthological Society 16:694-709
	Related studies in the Everglades: We are also analyzing population structure of eastern mosquitofish, spotted sunfish, yellow bullhead catfish, and grass shrimp from across the Everglades using allozymes and microsatellite DNA. This work is linked to studies of fish movement and dispersal, especially with regards to water management and seasonal hydrology. We have found evidence that long-hydroperiod marshes are source sites for fish to nearby short-hydroperiod marshes, and that the scale of fish movement is linked to fish size. Everglades marshes are structured along the dominant path of water flow into ridges and sloughs (an example from a vegetation map of the Shark River Slough is shown at left, dense sawgrass grows on the ridges). We believe that this structures fish movements and we favor a local concentration model for small fishes and a regional model for large ones (see below).  DeAngelis, D. L., J. C. Trexler, and W. F. Loftus.  2005. Life history trade-offs and community dynamics of small fishes in a seasonally pulsed wetland.  Canadian Journal of Fisheries and Aquatic Sci. 62:781-790 McElroy, T. C., L. L. Kandl, J. Garcia and J. C. Trexler.  2003. Extinction-colonization dynamics structure genetic variation of spotted sunfish (Lepomis punctatus) in the Florida Everglades.  Molecular Ecology 12:355-368.