Characteristics of Channel Darter Habitat in the Winooski River, Vermont

Douglas E. Facey and Shannon M. O ‘Brien Department of Biology

Saint Michael’s College

Colchester, Vermont

Photo by Rob Criswell, from the Pennsylvania Department ofConservation and Natural Resources web site (http://www.dcnr.state.pa.us/wrcf/chdart.htm)

AbstractChannel darters (Percina copelandi) are found in the southern, central, and northeastern United States and southeastern Canada, but their populations are often highly localized and have declined dramatically in some areas. This decline is believed to be the result of habitat degradation due to sedimentation. In Vermont, channel darters have been found in only three Lake Champlain tributaries. The species was first reported in the Winooski River in 1996, and only a few individuals had been captured prior to 2002. Channel darters also are rare in the Poultney River, and only three have been found in the LaPlatte River. Therefore, little is known of their distribution and habitat use in this part of their range. Forty-four channel darters were captured during a study in the Winooski River in summer of 2002. Sampling was done in 3 X 10 m plots, and water depth, surface velocity, and substrate samples were taken at each plot. Channel darters were caught in six of 56 plots, but 24 of the 44 channel darters caught were from one plot. Sample plots with channel darters had substrate that averaged (by weight) over 60% particles over 1.9 mm in size, and less than 7% particles under 0.23 mm.

Background• Channel darters have a widespread distribution in

North America, but are rare in Vermont– Only known in 3 rivers in Vermont - the Poultney River,

LaPlatte River, and Winooski River– First found in the Winooski River in 1996, with only few

individuals found prior to 2002• In much of the rest of the species’ range, there is

concern about impacts of habitat degradation on local populations

• Habitat use by channel darters has not been studied in the Lake Champlain basin

• During a study of habitat use by eastern sand darters (Ammocrypta pellucida), 44 channel darters were caught and substrate samples were taken from sample plots, allowing evaluation of use of habitat by channel darters– Results of eastern sand darter study are provided in oral

presentation at this conference (O’Brien and Facey)

North American range of the Channel Darter, Percina copelandi

(Map from Page, 1983)

Lake Champlain

Objective - Characterize habitat used by channel darters by comparing substrate composition of plots with channel darters present to plots with no channel darters

The Winooski River flows into Lake Champlain just north of Burlington, Vermont. Lake Champlain flows northward into the Richelieu River, which empties into the St. Lawrence River near Montreal.

Richelieu River

Winooski River

0 20

kilometers

Burlington

Plattsburgh

VERMONTNEW YORK

QUEBEC

North

Field Methods• Sampled 10 X 3 m plots

in areas that were less then 1 m deep

• Collected a representative sample of substrate for each plot

• Recorded number of fish of each species caught in each plot

Calculated Chi Square to determine if channel darters were randomly distributed – used Poisson distribution to determine expectation

Analysis for random distribution

Lab Analysis• Dried and separated

substrate samples into different size components using sieves

• The sieve screen sizes used were #5 (4.1 mm), #10 (1.9 mm), #18 (1.0 mm), #35 (0.54 mm) , #60 (0.23 mm), and #120 (0.12 mm)

• Calculated % composition by mass for each substrate size category

Table 1. Chi square analysis for randomness of distribution

Number of channel

darters per plot

Probability (based on Poisson

distribution)

Expected number of

plots (based on

probability)

Observed number of

plots

0 0.456 25.5 50

1 0.358 20.1 2

2 or more 0.186 10.4 4

Chi square = 43.7; df = 1; P<0.00001Conclusion – channel darters were not randomly

distributed among the plots sampled

Results• Channel darters were not randomly distributed among plots

(Chi square = 43.7; P<0.00001)– Of 44 total channel darters caught, 24 were in one plot, and

12 were in another plot.– 50 of 56 plots had no channel darters

• All areas sampled were less than one meter deep and with water velocity less than 0.5 m/sec– Plots with channel darters were under 35 cm deep and had

water velocities less than 0.4 m/sec• Substrate in plots with channel darters had a higher percent

composition of coarse particles (1.9 - 4.1 mm, > 4.1 mm) and also had considerably less fine substrate (< 0.12 mm, 0.12 - 0.23 mm., and 0.23 - 0.54 mm) than plots with no channel darters. – Well over 50% of substrate in plots with channel darters

were particles >1.9 mm.– On average, substrate under 0.54 mm made up over 40% of

substrate in plots with no channel darters, but less than 20% of substrate in plots with channel darters.

Density of Channel Darters (number per 30 m2)

0 1 2 4 12 24

Number of Plots 50 2 1 1 1 1

Substrate Size:

<.12 mm2.85

(+ 4.11)

0.88(+ 0.27)

1.28 1.10 0.45 1.19

0.12-0.23 mm10.49

(+ 11.90)

4.28(+ 0.59)

5.24 4.54 3.01 5.88

0.23-0.54 mm30.90

(+ 24.12)

16.73(+ 5.30)

9.47 9.08 13.85 12.91

Table 2. Mean percent substrate composition (+SD) of plots sampled. Note that plots with channel darters had less fine substrate (<0.54 mm) and more coarse substrate (>1.9 mm) than plots with no channel darters.

0.54-1.0 mm15.60

(+ 16.36)

13.31(+ 4.89)

10.95 10.51 13.33 14.26

1.0-1.9 mm5.50

(+ 5.45)

6.20(+ 1.64)

9.16 7.22 6.89 8.88

1.9-4.1 mm6.24

(+ 5.37)

10.58(+ 0.54)

13.56 10.30 10.73 12.52

> 4.1 mm28.74

(+ 29.67)

48.02(+ 1.55)

50.34 57.25 51.74 44.38

Conclusions• Channel darters were found in plots with over 50% of

the substrate composed of particles greater than 1.9 mm in size and with less than 20% of the substrate composed of particles less than 0.54 mm in size

• Prior to this study, very few channel darters had been found in the Winooski River, or elsewhere in Vermont– Perhaps there has been insufficient effort to more

fully evaluate the population in the past– Channel darters appear to be very patchily

distributed - 36 of 44 channel darters caught were in 2 of 56 plots sampled

– Perhaps the population in Vermont is increasing, either due to habitat improvement, climate change, or a combination of these and other factors.

Acknowledgments - this study was supported by funding from

–The Lake Champlain Research Consortium–The Clare Boothe Luce Foundation–Saint Michael’s College