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Dr. Jon Shenker

Research Interests

Fish - any kind, any question. If it's got fins, we're interested. Research in my laboratory focuses on a very diverse range of fish and fisheries issues. The ultimate goals of much of this research are to characterize and analyze the biological and ecological factors affecting fish populations, and to assist in the development of fish and habitat management strategies.

Other projects focus on the basic biology and physiology of fishes, still other efforts are examining the biological and commercial aspects of finfish aquaculture. Much of this work involves intensive field work, often developing and using novel sampling gear to answer specific questions. The work also often involves laboratory research, ranging from molecular genetics to the use of Nuclear Magnetic Resonance spectroscopy to examine fish physiology in vivo to ICP-MS analysis of fish otoliths.

One major focus of my work is an investigation of the processes affecting the recruitment and survival of larval and juvenile fishes. We've worked on numerous species in previous years, including grouper and snapper, and we're now spending a lot of effort on tarpon. Catching a huge tarpon is the dream of anglers throughout the country, who spend great sums to fish in the clear waters in the Florida Keys or the Caribbean. Our tarpon fishing is a bit different - we use moored plankton nets to capture larvae migrating from the ocean to the estuary, and we wade through thick mud, murky water and tangles of mangrove trees to capture tiny tarpon in their brackish marsh nursery habitats. A variety of factors are under investigation, including analysis of factors impacting the timing and magnitude of recruitment, estimating population sizes in marshes, characterizing their growth and survival rates, and analyzing their feeding biology and bioacoustics.

Another major research effort is on the utilization of artificial reefs by fish populations, with special emphasis on assessing the impact of fishing pressure on the reefs. This project involves extensive scuba surveys using visual and video monitoring of a series of massive artificial reefs deployed in 70' of water 10 miles off the Florida coast. Finally, in addition to our research activities, I run our summer field program in Australia, where we provide students with an intense 6-week immersion in the wonderful marine and terrestrial ecosystems of that spectacular region of the world.

My laboratory this year has seven graduate students and five undergraduate students working on various aspects of these and a diverse range of other projects. Funding is currently being provided by the Florida Fish and Wildlife Conservation Commission, and additional support is being sought from several governmental and private agencies, including our new Florida Tech Sportfish Research Institute.

Selected Publications

  • Shenker, J.M, E. Cowie-Mojica and H. Patterson. In press. Recruitment of larval tarpon (Megalops atlanticus) into the Indian River Lagoon, Florida: Cyclical and hurricane-driven transport. Contrib. Mar. Sci.
  • Shenker, J.M, R.E. Crabtree, H. Patterson, C. Stevens and K. Yakubik. In press. Spawning date and age at recruitment of larval tarpon (Megalops atlanticus) into the Indian River Lagoon. Contrib. Mar. Sci.
  • Patterson, H.M., S.R. Thorrold and J.M. Shenker. 2000. Analysis of otolith elemental fingerprints in Nassau grouper (Epinephelus striatus) from the Bahamas and Belize using solution-based ICP-MS. Coral Reefs 18:171-180.
  • Poulakis, G.R., J.M. Shenker and D. Scott Taylor. 2000. Habitat use by fishes after tidal reconnection of an impounded estuarine wetland in the Indian River Lagoon, Florida (USA). Wetlands Ecology and Management 1-19
  • Samson, J.C. and J. Shenker. 2000. The teratogenic effects of methylmercury on early development of the zebrafish, Danio rerio. Aquatic Toxicology 48:343-354.
  • Harndon, C.W, R. E. Crabtree and J. M. Shenker. 1999. Onshore transport of elopomorph leptocephali and glass eels (Pisces: Osteichthyes) in the Florida Keys. Gulf of Mex. Sci. 17:17-26.
  • Shenker, J.M. , R. Crabtree and G. Zarillo. 1995. Recruitment of larval tarpon and other fishes into the Indian River Lagoon. Bull. Mar. Sci. 57:284.
  • Mojica, R., J.M. Shenker, C. Harndon and D. Wagner. 1995. Recruitment of bonefish, Albula vulpes, around Lee Stocking Island, Bahamas. U.S. Fish. Bull. 93:666-674.
  • Thorrold, S.R., J.M. Shenker, E. Wishinski, R. Mojica and E.D. Maddox. 1994. Larval supply of shorefishes to nursery habitats around Lee Stocking Island, Bahamas. I. Small-scale distribution patterns. Mar. Biol. 118:567-578.
  • Thorrold, S.R., J.M. Shenker, E.D. Maddox, R. Mojica and E. Wishinski. 1994. Larval supply of shorefishes to nursery habitats around Lee Stocking Island, Bahamas. II. Lunar and oceanographic influences. Mar. Biol. 118:567-578.
  • Thorrold, S. R., J. M. Shenker, R. Mojica and H. Patterson. 1994. Temporal patterns in the larval supply of summer-recruiting reef fishes to Lee Stocking Island, Bahamas. Mar. Ecol. Prog. Ser. 112:75-86
  • Shenker, J.M., S.R. Thorrold, E.D. Maddox, S. Pearl, E. Wishinski, and N. Smith. 1993. Onshore transport of settlement-stage Nassau grouper (Epinephelus striatus) and other fishes in Exuma Sound, Bahamas. Mar. Ecol. Prog. Ser. 98:31-43.

Dr. Ralph Turingan

Research Interests

My research centers on the ecology and evolution of organismal design in vertebrates, using the fish-feeding system as a model. Fishes inhabit a wide range of habitats and feed on a variety of prey organisms. The functional morphology of the feeding mechanism in fishes is one of the most diverse in the animal kingdom. The ultimate goal of my research is to elucidate the roles of ecological and evolutionary processes in explaining organismal diversity.

In one of our major current projects, we explore the causal mechanisms that underlie mortality in marine fish larvae. We focus our attention at the critical period of first feeding, which is hypothesized to be a bottleneck in the recruitment of marine fishes. We investigate the consequences of the development of feeding functional design on the prey-capture performance of marine fish larvae. During early ontogeny, the feeding mechanism in marine fishes develops from a simple system that is mediated by the hyoid apparatus to a more complex mechanism that involves both the hyoid and opercular systems. However, we still do not know if this morphological transformation is one of the underlying causes of mortality in marine fish larvae through its influence on prey-capture performance.

We address several questions including: (1) How does the feeding mechanism develop during the early-life history stages of marine fishes? (2) How does the feeding mechanism of marine fish larvae work? (3) Does the kinematics of prey capture vary between the hyoid and the operculo-hyoid stages of lower-jaw depressing mechanisms? (4) Does the kinematics of prey capture vary among prey types, among species of marine fish larvae, and among early developmental stages (hyoid vs. hyoid + operculum stage) of fish. (5) How do early ontogenetic changes in biomechanical design of the prey-capture mechanism influence prey-capture performance in marine fish larvae? (6) Does feeding efficiency in marine fish larvae improve with the development of a more complex feeding mechanism through early ontogeny?

Other projects in our laboratory involve our continuing investigations of the intraspecitic and interspecific variation in feeding biomechanics and behavior in coral reef and estuarine fishes. Estuaries and lagoons comprise about 90% of the Atlantic and Gulf coasts of the United States. These habitats serve as nursery grounds for a number of fish species, including those of commercial and recreational importance. However, in spite of the biological importance of these coastal environments, anthropogenic activities continue to cause variations in physico-chemical factors that influence the physiology and behavior of fishes. Environmental changes in temperature, salinity, food supply, and microhabitat characteristics within these coastal ecosystems have created new problems for the local fish fauna. Our lack of understanding of how fishes solve these problems underscores the need for studies that explore the compensatory mechanisms (e.g., morphological and physiological) that enable fishes to counteract these environmental perturbations. One important physiological/behavioral process that is sensitive to environmental conditions is foraging performance in fishes. The role of phenotypic and physiological plasticity in creating a diverse feeding system in fishes is one of the least understood phenomena in fish biology.

The Indian River Lagoon (IRL), an estuarine environment on the east-central coast of Florida, consists of a high diversity of habitats, such as mangrove forests, salt marshes, freshwater tributaries, seagrass beds and estuaries, and supports one of the most diverse fish faunae in North America. The IRL provides a natural ecosystem for students in my laboratory to conduct experiments in the wild, that complements laboratory-based experiments, in order to explore the relationship between fish populations and their habitats, particularly those species that inhabit a variety of habitats

Selected Publications

  • Krebs, J.M. and Turingan, R.G. 2002. Intraspecific variation in gape-prey size relationships and feeding success during early ontogeny in red drum, Sciaenops ocellatus. Environmental Biology of Fishes. In press.
  • Huskey, S.H. and Turingan, R.G. 2001. Variation in prey-resource utilization and oral jaw gape between two populations of largemouth bass, Micropterus salmoides. Environmental Biology of Fishes 61:185-194.
  • Durie, C.J. and Turingan, R.G. 2001. Relationship between durophagy and feeding biomechanics in gray triggerfish, Balistes capriscus: intraspecific variation in ecological morphology. Florida Scientist. 64(1):20-28.
  • Cutwa, M., Turingan, R.G. 2000. Intralocality variation in food habit and feeding biomechanics in the sheepshead, Archosargus probatocephalus, with implications for the ecomorphology of fishes. Environmental Biology of Fishes 59:191-198.
  • Wainwright, P.C. and Turingan, R.G.. 1997. Evolution of pufferfish inflation behavior. Evolution 5(2): 506-518.
  • Turingan, R.G., Wainwright, P.C. and Hensley, D.A. 1995. Interpopulation variation in prey use and feeding biomechanics in triggerfishes. Oecologia. 102:296-304.
  • Turingan, R.G. 1994. Ecomorphological relationships among Caribbean tetraodontiform fishes. J. Zool., London. 233:493-521.
  • Turingan, R.G. and Wainwright, P.C. 1993. Morphological and functional bases of durophagy in the queen triggerfish, Balistes vetula (Pisces, Tetraodontiformes). J. Morph. 215:101-118.
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