Habitat Use and Substrate Preference of Eastern Sand Darters in Vermont Shannon O’Brien and Douglas E. Facey Department of Biology, Saint Michael’s College Colchester, Vermont USA

Outline Background on the eastern sand darter Methods and results from field studies Methods and results from the lab experiment General conclusions

Introduction Globally rare Historical decline in other parts of their range, perhaps due to habitat alterations Little historical data is available for the populations found in Vermont

Objective Field Studies (2001 and 2002) Compare the substrate composition and the number of Eastern Sand Darters found to determine if their distribution was related to the substrate

Richelieu River Missisquoi River Lamoille River Winooski River Poultney River 020 kilometers Burlington Plattsburgh VERMONTNEW YORK QUEBEC Poultney River (2001) southern most part of Lake Champlain 1-mile stretch Winooski River (2002) Near Burlington, VT 6-mile stretch Study Sites

Field Methods Sampled 10 X 3 m plots in areas that were less than 1 m deep Substrate sample for each plot Recorded number of fish caught for each plot focusing on ESD Analysis Chi square for Poisson distribution to determine if randomly distributed

Analysis Separated substrate samples with sieves 7 Substrate size categories <.12mm mm mm mm mm mm >4.1mm Calculated % composition by mass for each substrate size category

Results from the Poultney River 42 eastern sand darters were found in 19 of the 99 different plots

Results – Poultney River Chi square(x 2 )= 17.85, P = , df=1 Eastern sand darters were not randomly distributed according to the Chi square results for the Poisson Distribution Number of Fish Observed number of plots Expected value

Results – Poultney River General Trends Between Eastern Sand Darter Density and Substrate Composition Lowest density in plots with the highest percentage of gravel (> 1.9 mm) Density increased as the percentage of gravel decreased, in most cases The plots with 4 and 6 eastern sand darters had a high percentage of fine and medium sand ( mm and mm)

Density of Eastern Sand Darters (number per 30 m 2 ) # of Plots Percent Substrate: <.12 mm 3.2 (±3.2) 1.6 (±1.1) 2.4 (±1.5) 2.7 (±1.0) mm 10.3 (±10.8) 6.1 (±3.8) 7.8 (±5.3) 18.0 (±2.7) mm 26.9 (±15.8) 28.1 (±13.7) 29.6 (±22.3) 60.4 (±6.97) mm 14.3 (±12.3) 19.1 (±10.1) 14.1 (±8.4) 13.2 (±3.0) mm 10.5 (±6.5) 14.3 (±8.5) 18.1 (±12.6) 2.2 (±2.2) mm 12.5 (±7.9) 12.1 (±7.8) 17.3 (±11.8) 2.0 (±1.9) > 4.1 mm 22.5 (±19.2) 18.6 (±19.6) 10.8 (±8.2) 1.7 (±1.6)

Results from the Winooski River 112 eastern sand darters were found in 12 of the 56 plots Seventy-four of the eastern sand darters were caught in one plot

Results – Winooski River Chi square(x 2 )= 199.2, P = 6.07 x Eastern sand darters were not randomly distributed according the Chi square results for the Poisson Distribution Number of Fish Observed number of plots Expected value

Results – Winooski River General Trends Between Eastern Sand Darter Density and Substrate Composition Less abundant in areas with a high percentage of gravel (> 1.0 mm) Large densities found in areas with a higher percentage of medium- sized sand ( mm) and more coarse sand ( mm)

Density of Eastern Sand Darters (number per 30 m 2 ) # of Plots % Substrate: <.12 mm 2.6 (±4.2) 3.3 (±3.3) (±0.38) mm 9.5 (±12.2) 7.4 (±5.9) (±3.9) mm 28.0 (±25.0) 21.0 (±13.2) (±20.6) mm 13.0 (±13.8) 20.6 (±24.4) (±26.8) mm 5.7 (±5.5) 7.2 (±3.79) (±6.9) mm 7.1 (±5.4) 9.4 (±5.1) (±5.24) > 4.1 mm (±29.5) (±26.3) (±35.9)

Summary of Results Eastern sand darters were not randomly distributed in either river Trends for eastern sand darter distribution and substrate composition Higher density of fish in areas with low percentage of coarse substrate Usually a high percentage of medium sized sand in areas with more eastern sand darters Field studies did not test preference so followed up with a lab experiment to test preference

Objective Lab Study (2002) Determine if eastern sand darters prefer a certain size particle when given a choice of 4 different sizes within a tank Predictions Eastern sand darters will show a preference for the smaller sized substrate

Methods for Lab Divided the bottom of 4 tanks into 4 equally sized rectangles with plastic dividers ~2.5 cm high Filled each rectangle with one of four different size particles mm, mm, mm, or mm Each tank had a different orientation of the four particle sizes Fish were kept for one week and observed daily, approximately every 2 hours Recorded which size sediment they were over or burrowed into Performed chi square using the first observation made for each fish on their 4th day in the tank Determined if eastern sand darters showed a preference for burrowing in a substrate consisting of a certain sized particle

Results – Lab Study A total of 49 fish were observed between August 2002 and Oct 2002 Based on a total of 912 observations, eastern sand darters were burrowed 790 times (86.6 %) and were not burrowed 122 times (13.3 %)

Eastern sand darters burrowed the most in sediment less than 1.0mm (73%)

Chi Square Analysis Used first observation made on 4 th day for each fish that was burrowed (N=46) Chi square(x 2 )= 19.6, P< 0.005, df=3 Showed a statistically significant preference for sediment ranging in size mm Sediment size (mm) Observed # of Observations

Conclusions The Lab results supported the field observations from both the Poultney and Winooski Rivers Utilize and prefer areas with a high percentage of sediment mm in size Sediment size influences their distribution Indicates they are selective Alterations in the sediment of rivers may impact their ability to utilize certain habitats

Acknowledgements Thanks to… The Vermont Nature Conservancy, which generously funded the Poultney River Project in 2001 The Lake Champlain Research Consortium for funding both the Poultney and Winooski River work The Clare Boothe Luce Scholarship Fund which also providing funding for both projects References Daniels, R.A Significance of burying in Ammocrypta pellucida. Copeia 1989: Daniels, R.A Habitat of the eastern sand darter, Ammocrypta pellucida. Journal of Freshwater Ecology 8: Facey, D. E Status of the Eastern sand darter (Ammocrypta pellucida) in Vermont. Canadian Field-Naturalist 112: