scholarly journals Habitat Use by the Eastern Sand Darter, Ammocrypta pellucida, in Two Lake Champlain Tributaries

2008 ◽  
Vol 122 (3) ◽  
pp. 239 ◽  
Author(s):  
Shannon M. O'Brien ◽  
Douglas E. Facey

The Eastern Sand Darter (Ammocrypta pellucida) is endangered or threatened throughout much of its range, which includes the St. Lawrence-Lake Ontario drainage of southern Ontario and Quebec and several Vermont tributaries of Lake Champlain. The species is known for its tendency to burrow, and field observations have suggested that habitat use may depend on substrate particle size. To determine whether Eastern Sand Darter densities were correlated with substrate particle size, fish and substrates were sampled in 156 plots in two Vermont rivers during the summers of 2001 and 2002. The Eastern Sand Darter occurred mainly in areas in which substrate composition was over 45% fine to medium sand (0.24-0.54 mm); they were much less abundant in areas in which substrate composition exceeded 25% particles greater than 1.9 mm. Substrate preference was tested by allowing 49 fish kept in aquaria to choose among four different substrates. The fish showed a significant preference (P < 0.005) for the finer substrate categories (0.24-0.54 mm, 0.55-1.0 mm), and mostly avoided the coarser substrates (1.0-1.9 mm, 2.0-4.1 mm). This suggests that the Eastern Sand Darter is selective regarding substrate composition, and therefore might be affected by fluctuations or changes in substrate composition within its habitat, such as those caused by changes in flow.

1996 ◽  
Vol 18 (2) ◽  
pp. 121-125 ◽  
Author(s):  
M.P. Nandakumar ◽  
M.S. Thakur ◽  
K.S.M.S. Raghavarao ◽  
N.P. Ghildyal

1991 ◽  
Vol 48 (10) ◽  
pp. 1882-1886 ◽  
Author(s):  
Michael K. Young ◽  
Wayne A. Hubert ◽  
Thomas A. Wesche

We compared samples collected from 10 substrates of various compositions with a single-probe freeze-core sampler, a triple-probe freeze-core sampler, a McNeil sampler, and a shovel. The accuracy with which these devices sampled particles larger than 50 mm in diameter varied; they were oversampled by the freeze-core devices, sampled in proportion to their availability by a shovel, and sampled inconsistently by the McNeil sampler. The geometric mean particle size and variance of single-probe freeze-core samples consistently exceeded those of samples collected with the other devices. Most sample means also exceeded the test substrate means. By excluding the proportions of particles larger than 50 mm in diameter in our analyses, we found that proportions of several particles sizes in samples collected by different methods differed significantly from the actual proportions in test substrates. There were few differences between the single- and triple-probe freeze-core samples or between McNeil and shovel samples. All four samplers were biased, but the McNeil sampler most frequently produced samples that approximated the true substrate composition.


1978 ◽  
Vol 15 (6) ◽  
pp. 1025-1036 ◽  
Author(s):  
W. R. Cowan

Linear and quadratic trend surfaces were computed for textural, carbonate, clast, and heavy mineral properties of the Catfish Creek (Nissouri Stadial), Port Stanley (Port Bruce Stadial), Tavistock (Port Bruce Stadial), and Wentworth (Port Huron Stadial) tills.Catfish Creek Till pebble grade material provided trend surfaces reflecting the underlying bedrock. However, an overall lack of regional trends in Catfish Creek Till is consistent with field observations that indicate remarkable uniformity for this till over several hundred square kilometres, a phenomenon that is believed to reflect the high energy of this ice sheet. Carbonates in Port Stanley Till were found to increase from east to west as the Silurian–Devonian contact was crossed. Tavistock Till was found to have increasing sand content and decreasing silt content from northwest to southeast owing to incorporation of underlying glaciofluvial sediments; pebble trends reflect the underlying bedrock for the most part. Wentworth Till trend surfaces for carbonates and pebbles show high dolomite near the Niagara Escarpment to the east and northeast with a dilution of dolomite and influx of limestone to the southwest.The strong relationship of the trend surfaces to substrate materials indicates the basal nature of the tills and the local origin of most glacial deposits. Pebble lithologies provide much information about local bedrock and drift prospectors should give close consideration to coarse fragments.


1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.


1994 ◽  
Vol 51 (11) ◽  
pp. 2603-2611 ◽  
Author(s):  
W. Gary Sprules ◽  
Andy P. Goyke

Analytical solutions to allometric models of predator–prey interactions in aquatic ecosystems indicate that normalized biomass spectra should consist of a smooth quadratic trend around which periodic oscillations occur. We confirm these assertions by showing that parabolas provide good models of normalized biomass as a function of body mass within homogeneous trophic groupings of organisms (phytoplankton, zooplankton, or fish) in the pelagic food webs of Lakes Ontario and Michigan. In addition, we show that the normalized biomass spectrum for the whole pelagic community in these lakes can be modelled by a series of parabolas of constant curvature that are aligned along a smooth quadratic base, as predicted by theory. Total secondary production in Lake Ontario is predicted from these models to be 234 kcal∙m−2∙yr−1 (1 kcal = 4.19 kJ), which compares favourably with sampling estimates of about 154 kcal∙m−2∙yr−1 for the whole community except rotifers and some hypolimnetic organisms, but both are higher than particle-size conversion efficiency estimates of 75–125 kcal∙m−2∙yr−1.


2015 ◽  
Vol 41 (4) ◽  
pp. 1037-1051 ◽  
Author(s):  
Masoud Asadzadeh ◽  
Luis Leon ◽  
Craig McCrimmon ◽  
Wanhong Yang ◽  
Yongbo Liu ◽  
...  

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 141 ◽  
Author(s):  
Megan Manley ◽  
Michael Melzer ◽  
Helen Spafford

The coconut rhinoceros beetle (CRB), Oryctes rhinoceros (L.) (Coleoptera: Scarabaeidae), has become one of the most important coconut and oil palm pests. This species was detected attacking coconut palms on Oʻahu, Hawaiʻi in December 2013, and an eradication program was initiated. One of the major challenges for eradication has been the identification of new breeding sites. Information on the factors influencing oviposition is needed to aid in finding sites likely to host the immature stages of this insect. In this study, a series of choice tests were conducted to assess the oviposition preferences of both laboratory-reared and wild-caught CRB. Mated females, of both lab-reared and wild-caught beetles, were offered for oviposition a choice between sand and two mulch substrates, one with small and one with large particle sizes. Both types of CRB laid eggs preferentially in substrate of small particle size rather than large and none laid eggs in sand. Lab-reared and wild-caught CRB differed in their oviposition behavior and size. These results can be used to aid in the identification of breeding sites for management programs and eradication efforts.


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