Associate Professor of Biology
Hartwick College
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Address |
Biology Department, Hartwick College, Oneonta, NY 13820 |
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Office |
337 Johnstone Science Center |
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Telephone |
(607)-431-4768 |
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Fax |
(607)-431-4374 |
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= Top==Education==Research==Publications===Courses==Links==
My research lies at the interface of behavioral, population, and community ecology. I am broadly interested in the mechanisms (e.g., behaviors) involved in intra- and interspecific interactions and how these interactions affect populations and communities. My general approach is to develop a thorough, mechanistic understanding of a community and its component populations. Since sound ecological theories require an understanding of mechanisms and a firm foundation of empirical data, this type of research is important for the further growth of ecology.
In 1999, I started a quantitative sampling program to determine the distribution and abundance of crayfish species in creeks and rivers in the Pine Lake area (Kuhlmann & Hazelton, 2007). The main focus is a non-native species, the rusty crayfish, Orconectes rusticus. Sometime after 1969, the rusty crayfish was introduced into the upper Susquehanna River and has since spread into many tributaries. Rusty crayfish are native to the Ohio River but have been recently introduced to many rivers and lakes throughout the upper Midwest and Northeastern US and southern Canada. Most research on introduced populations of rusty crayfish has been done in lakes in Wisconsin, where the species is known to displace native crayfish species and alter the composition of lake communities. Much less is known about the effects of introduced rusty crayfish in streams. The overall objectives of this research program are to 1) monitor the distribution of introduced and native crayfish in the upper Susquehanna River and its tributaries, 2) examine the mechanisms that allow the rusty crayfish to invade stream habitats, and 3) determine the effects of rusty crayfish on local stream communities. Comparing the mechanisms and effects of O. rusticus’s invasion of streams to previous findings in lakes will provide ecologists with a broader understanding of the causes and consequences of species introductions.
The mottled sculpin is a stream-dwelling, shelter-nesting fish that is distributed widely in North America. During the breeding season (spring and early summer), male sculpins occupy cavities under rocks and other stream debris. Females lay eggs in a discrete mass inside the nest of a male, who then fertilizes and guards the eggs until they hatch.
Interactions – Mottled sculpin and rusty crayfish (Orconectes
rusticus) share a suite of predators,
especially large fish like smallmouth bass (Micropterus dolomieu), and use the same refuges (rocks) to avoid
predators. As a result, the
presence of one of these species may affect the other’s interaction with
predators, either by influencing refuge use by the prey or altering the
predators’ behavior. Ongoing
student research involves experiments in outdoor artificial pools to compare
the mortality rates and behaviors of crayfish and sculpin with and without
smallmouth bass predators. The
experiment will allow us to determine if the presence of alternate prey has an
effect on bass predation on crayfish and sculpin. The behavioral observations will allow us to determine the
mechanism of any observed effects.
Mating systems
ecology - Mating systems theory
attributes variation in mating strategies (patterns of mate choice and
competition) to variation in the availability of resources required for
reproduction. Shelter-nesting fish are excellent for mating systems
research because the critical resource, the nest, is easily identifiable. Also,
resource availability is likely to vary greatly in nature and the resource can
often be easily manipulated experimentally. Initial phases of
research on sculpin mating strategies have included: 1) gathering baseline
population data, such as distribution, abundance, size structure, and reproduction;
2) pilot experiments to assess the feasibility of field manipulations; and 3)
laboratory shelter competition experiments.
Initiated in 2003,
this project aims to survey the coastal habitats of San Salvador Island,
Bahamas, to determine the abundance and distribution of juvenile spiny lobster
(Panulirus argus) and juvenile
lobster habitat. My objective is to investigate potential life-history
bottlenecks that may limit the abundance of adult spiny lobsters around San
Salvador Island, in the context of gaining a broader understanding of the
ecology and dynamics of P. argus
population ecology. This research will add to the understanding of the
population ecology of a commercially- and ecologically-important marine
species, the Caribbean spiny lobster. Much of what we know about spiny
lobster population ecology comes from studies in the Florida Keys, although the
ecological conditions there are not representative of much of the spiny
lobster’s range. This study will expand that knowledge by examining the ecology
of P. argus in a different
ecological setting.
Past research, in collaboration with A. H. "Tuck" Hines of the Smithsonian Environmental Research Center, aimed at understanding the role of interspecific interactions in regulating populations and the behavioral mechanisms driving these interactions. We investigated the significance of a predator's functional response on its prey's population in a model predator-prey system: the blue crab, Callinectes sapidus, preying on the Baltic clam, Macoma balthica, in the upper Chesapeake Bay (Kuhlmann & Hines, 2005). Theory suggests that certain types of predator functional responses, the relationship between prey density and the proportion of prey a predator eats, might promote prey population stability. Earlier research showed that, in laboratory mesocoms, individual blue crabs eat proportionally fewer clams at lower prey densities. Thus, the clams should have a partial refuge from predation at low densities, allowing the prey population to persist in the presence of the predator. We extended this research by addressing two main questions: 1) Does the functional response of individual predators in the lab predict patterns of prey mortality in the field, when multiple predators will be involved? 2) What behavioral mechanisms in the predator are responsible for the patterns of prey mortality? We addressed these questions with a combination of mesocosm and field studies to measure clam mortality rates and blue crab foraging behavior under a variety of conditions. The functional response of individual blue crabs does not predict the patterns of clam mortality in the field; that is, the effect of a population of blue crabs is different than the effects of an individual. Thus, blue crab behavior in the field, either in terms of foraging or distribution, must be different than that of individual crabs in isolation. Agonistic behaviors were not significantly affected by clam density, but the presence of a conspecific increased a crab’s foraging time at the lowest clam density. Changes in behavior when multiple crabs forage together may partly account for the reduction in density dependence of clam mortality. Predator responses such as the effects of conspecifics on foraging and patch choice that were lacking in the laboratory appear to be key in determining prey mortality patterns in the field. Larger-scale patterns of prey density variation were more important in determining prey mortality rates than the small-scale variation represented by the experimentally-manipulated patches.
A second project
investigated how refuges from predation modify both the direct and indirect
effects of interspecific interactions in an estuarine community of moderate
trophic complexity. Although the effects of refuge are well documented for
simple communities, little is known about its effects on complex trophic
interactions in more diverse communities. Because of indirect effects, the
impacts of refuge in more diverse communities are not easily predicted from simpler
systems. In the upper Chesapeake Bay, coarse woody debris (CWD) is used by the
grass shrimp Palaemonetes pugio
and an intermediate predator, the mummichog Fundulus heteroclitus, as a refuge from larger predators (of both species),
especially the white perch Morone americana. We found that grass shrimp altered their use of
shelter depending on what predators were present: shrimp aggregated at CWD when
no predators, white perch only, or both white perch and mummichog were present
in experimental mesocoms, but avoided the refuge in the presence of mummichogs
only.
My dissertation research focused on indirect effects in multi-species interactions and on nonconsumptive or nontrophic (i.e., not predation or competition) interactions, particularly the effects of biologically created shelters. Indirect effects occur when the interaction between two species is influenced by a third species. Mathematical models suggest that indirect effects can greatly affect the stability and complexity of species interactions within communities, but our current understanding of their importance or of the mechanisms involved is far from complete. Indirect effects involving nontrophic interactions are particularly poorly documented, since most empirical and theoretical studies have emphasized the roles of predation and/or competition.
I investigated
nontrophic indirect effects in seagrass communities, primarily in St. Joseph Bay
in the northeastern Gulf of Mexico. My research focused on interactions between
a predatory marine gastropod (the horse
conch, Pleuroploca gigantea)
and an assemblage of benthic fishes and invertebrates that shelter and/or lay
eggs in the empty shells left after the death of the gastropod's main prey, the
pen shell Atrina rigida. If it is
a major source of Atrina mortality,
the gastropod could regulate shelter availability, and thus indirectly affect
populations of the species that use the shells for shelter and/or reproduction.
If changes in pen shell availability affect some species more strongly than
others, horse conchs may also indirectly influence community composition.
My research
investigated two components of the indirect effect: (1) the effect of horse
conchs on Atrina mortality and (2)
the effects of pen shell availability on the occupant species. Conch exclusion
experiments, foraging observations and sampling indicate that horse conchs are
the main source of Atrina mortality
(Kuhlmann, 1994). However, while Atrina made up >90% of horse conchs' observed diet, conchs
did not show a functional or numerical (i.e., aggregation) response to pen
shell density (Kuhlmann, in press). These results suggest Atrina mortality rate, that is, the availability of new
shelters, will be determined primarily by horse conch abundance rather than Atrina
density. Shell addition experiments
demonstrated that three species of fish (two blennies
and a clingfish) responded most strongly to shelters mimicking freshly killed Atrina
(Kuhlmann, 1994).
Since the fishes use the shells not only for shelter but also as a site for reproduction, the gastropod predator may
influence both local abundance and reproductive output, which potentially
affects individual fitness. Subsequently, I conducted a four-month quantitative
manipulation of Atrina mortality
rate and measured both abundance and reproductive responses in the fishes.
Atrina mortality rate significantly affected reproductive output at both the
level of the individual and the population in one species, the Florida blenny, Chasmodes
saburrae (Kuhlmann,
1997).
I also collected
extensive data on Atrina population
dynamics (recruitment, growth, and mortality rates), dynamics of the shell
resource (fouling and loss rates), and shell utilization patterns during
several years of sampling in St. Joseph Bay (Kuhlmann,1998).
I combined the data from the conch foraging observations, shell manipulation
experiments, and Atrina and shell
sampling to construct a stochastic simulation model of this interaction web.
This model will help me tease apart the effects of the multiple interacting
factors involved in the indirect effect and can be used to make quantitative
predictions of the effect of horse conchs on fish reproduction under a variety
of conditions. I can then test these predictions in the field by directly
manipulating horse conch density and measuring the effect on the fishes. This
experiment is important because few, if any, models of interspecific
interactions are ever tested empirically, and because a manipulation of horse
conch density would be a definitive test of our understanding of the system.
I have also conducted research in a number of other areas. I have documented large differences in body size between two populations of the crab Pilumnus sayi that appear to be caused by differences in the sizes of available shelters. I have collaborated with another student in our lab (R. Walker) to measure the reproductive consequences of these size differences (Kuhlmann and Walker, 1999). My master's thesis research investigated behavioral predator-avoidance mechanisms in an intertidal hermit crab. Most research on hermit crabs has focused on shell selection as an antipredator measure; my study did not find any strong effect of shell type but demonstrated that predator-specific behavioral responses reduced predation risk (Kuhlmann, 1992). I also have conducted research on bird-mediated seed dispersal of gap-dwelling plants in Costa Rica (Murray et al., 1994).
= Top==Education==Research==Publications===Courses==Links==
Kuhlmann, M.L. 1992. Behavioral avoidance of predation in an intertidal hermit crab. Journal of Experimental Marine Biology and Ecology 157: 143-158.
Murray,
K.G., S. Russell, C.M. Picone, K. Winnett-Murray, W. Sherwood and M.L.
Kuhlmann. 1994. Fruit laxatives and seed passage rates in frugivores:
consequences for plant reproductive success. Ecology 75: 989-994.
Kuhlmann,
M.L. 1994. Indirect effects of a predatory gastropod in a seagrass community.
Journal of Experimental Marine Biology and Ecology 183: 163-178.
Kuhlmann,
M.L. 1997. Regulation of fish reproduction by a predatory gastropod: an
experimental investigation of indirect effects in a seagrass community. Journal
of Experimental Marine Biology and Ecology 218: 199-214.
Kuhlmann,
M.L. 1998. Spatial and temporal patterns in the dynamics and use of shell
shelters in St. Joseph Bay, Florida. Bulletin of Marine Science 62: 157-179.
Kuhlmann, M.L. and R. Walker. 1999. Geographic
variation in size structure and size at maturity in the xanthid crab Pilumnus
sayi in the northern Gulf of Mexico.
Bulletin of Marine Science 64: 535-541.
Allen, M. E., and M.
L. Kuhlmann. 2002. Search for the Missing Sea Otters: An Ecological
Detective Story. [A teaching case study]. Published online at the Case Study
Collection - National Center for Case Study Teaching in Science
Kuhlmann,
M. L., and A. H. Hines. 2005. Density-dependent predation by blue crabs Callinectes
sapidus on natural prey populations
of infaunal bivalves. Marine Ecology Progress Series 295: 215-228. pdf
Kuhlmann,
M. L. April 2006, posting date. Do Antbirds Help or Hinder Army Ants?
Teaching Issues and Experiments in Ecology, Vol. 4: Issues Figure Set #1
[online]. http://tiee.ecoed.net/vol/v4/issues/figure_sets/army_ants/abstract.html
Kuhlmann, M. L., and
P. D. Hazelton. 2007. Invasion of the upper Susquehanna River
watershed by rusty crayfish, Orconectes rusticus.
Northeastern Naturalist 14:507-518.
Kuhlmann, M. L., S.
M. Badylak, and E. L. Carvin.
2008. Testing the
differential predation hypothesis for the invasion of rusty crayfish in a
stream community: laboratory and field experiments. Freshwater Biology 53:
113-128. Available online at: http://www.blackwell-synergy.com/toc/fwb/53/1
Murray, K.G., K.
Winnett-Murray, J. Roberts, K. Horjus, W.A. Haber, W. Zuchowski, M. Kuhlmann,
and T.M. Long-Robinson. 2008. The roles of disperser behavior and
physical habitat structure in regeneration of post-agricultural fields.
Pp. 192-215, in R.W. Myster (editor): Post-agricultural succession in the
Neotropics. Springer. 308 pages.
Kuhlmann, M. L. In
Press. Do invading rusty crayfish interfere with reproduction in a native
congener? Journal of Crustacean Biology.
= Top==Education==Research==Publications===Courses==Links==
On-line course
information for recent or current courses without links above may be available
through Hartwick College Blackboard
server.
= Top==Education==Research==Publications===Courses==Links==