Comparison of larval thermal maxima between Fundulus heteroclitus and F. grandis
Fundulus heteroclitus and F. grandis are resident salt marsh fishes that overlap in distribution over a narrow range in northeastern Florida. The objective of the present study was to examine whether the limits of the species’ ranges could be explained by differences in thermal tolerance. Two populations of each species were collected and then spawned in the laboratory, and 9-day-old larvae were used for critical thermal maxima trials. Mean LOE temperatures of larvae ranged from 43.04 to 43.65°C and showed little difference between species. Therefore, differences in high temperatures experienced cannot account for the differences of the distributions of the two species. Condition-specific competition may play a greater role in determining the observed range of the two species.
KeywordsFundulus grandis Fundulus heteroclitus Thermal tolerance
The authors thank I. Gonzalez, E. Gonzalez, S. Jermanus and R. Norris for help with field collections and during experimental trials. Thanks to J.D. Hatle and G. Ehrlinger for critical reading of the manuscript, D.C. Moon for statistical analysis, and R. Gleeson and K. Petrinec for GTM NERR data. Support for the project was through funding from the University of North Florida Biology department and the Coastal Biology Flagship program.
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