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A recent review of deep-sea fishes captured deeper than 200 m off greater New England, from the Scotian Shelf at 44°N to the southern New England Shelf at about 38°N, documented 591 species. Subsequent trawling activity and reviews of deep-sea taxa occurring in the area have revealed that an additional 40 species inhabit the deep sea off New England. Thirty-two of these new records were captured in the course of 44 bottom trawls and 94 mid-water trawls over or in the proximity of Bear Seamount (39°55′N, 67°30′W). Five of the 40 species have been described as new to science, at least in part from material taken in the study area. In addition to describing such information as specimen size and position, depth, and date of capture, errors made in the previous study of deep-sea fishes in the area are identified and corrected.
Diverse freshwater lacustrine fishes enter tributaries to spawn, but resident riverine members may also occupy these same tributaries. While mark-recapture and biotelemetry studies suggest reproductive isolation between such populations, the assertion has rarely been tested genetically. To address this question, Micropterus dolomieu (Smallmouth Bass) from the southern shoreline of Lake Erie were compared genetically to bass in adjacent tributaries. Results from mitochondrial DNA sequences support the hypothesis that lacustrine and riverine populations segregate. Furthermore, divergences among tributary populations were often as large as those divergences between lacustrine and riverine bass, suggesting that each river population may become genetically distinct.
The diet of larval Semotilus atromaculatus (Creek Chubs) was examined in fish collected from an urbanized stream with a limited food base. Chironomids comprised nearly 90% of food items. They appeared in the gut of early larvae and continued to be the main food source as size increased; cladocerans were the second most abundant food item. Both average and maximum prey size were examined. Overall, average prey size increases significantly with standard length (SL). Maximum prey size is gape-limited twice, from the early to mid-mesolarval stage and again in the late mesolarval stage. Significant differences were observed in the maximum size of chironomids ingested among fish of four size ranges, <8.0 mm SL, 8.0–9.6 mm SL, 9.7–14.1 mm SL, and >14.1 mm SL, indicating maximum prey size increases rapidly at 8.0 mm SL, 9.6 mm SL, and again at 14.1 mm SL, yet maximum prey size within each group remains constant. The degree of cranial ossification and fin development at these break points was examined with cleared and double-stained specimens. For fishes <8.0 mm SL, ossification is just commencing, and maximum prey size is gape limited. At 9.6 mm SL, ossification appeared nearly complete in the caudal fin and in key bones involved in food capture and processing. There was no obvious correlation between ossification of the skeleton and the third break point at 14.1 mm SL. The results from this study suggest that ossification of feeding apparatus and caudal fin may play an important role in the ability of Creek Chubs to capture larger prey in the mesolarval stage at about 9.6 mm SL, but other factors likely account for the increase in prey size at about 14 mm SL.
The seasonal habitat use of Salvelinus fontinalis (Brook Trout) and sub-yearling Salmo salar (Atlantic Salmon) was examined in Hart Brook, a tributary of Lake Ontario. Fish habitat use and available habitat were examined during summer and autumn. Interspecific differences in habitat use occurred as well as intraspecific seasonal differences. Overyearling Brook Trout were more selective in their habitat preferences than subyearling Brook Trout or juvenile Atlantic Salmon. Depth and the amount of cover were significantly different among the three fish groups. Salmon occupied faster and shallower water than either age group of trout. Atlantic Salmon were also associated with larger-sized substrate materials than either trout age group, and salmon occurred in habitats with less cover than trout. Overyearling Brook Trout occupied deeper water with more cover than subyearling trout. All three salmonid groups occupied areas with more cover in autumn compared to summer. In autumn, subyearling Brook Trout used deeper areas than they had in the summer. In Hart Brook, the habitat of subyearling Atlantic Salmon can be generally characterized as riffles, the habitat of overyearling Brook Trout was deep pools with extensive cover (35%), and that of subyearling trout was any area with moderate flow and at least 20% cover. As efforts proceed to reintroduce Atlantic Salmon in Lake Ontario, further research is needed to ensure the conservation of Brook Trout populations.
Stream acidification across the northeastern US impacts fish abundance and fish communities. In this study, we document a fish community shift in the upper mainstem of Hubbard Brook (NH) from the presence of at least three species in the 1960s to the presence of only one species today. Cottus cognatus (Slimy Sculpin) and Rhinichthys atratulus (Blacknose Dace) are no longer present in this system, and we suggest that extirpation occurred during a period of chronic acidification during the early 1970s. Today, Salvelinus fontinalis (Brook Trout) is the only fish species present in the upper reaches of the Hubbard Brook Valley. The current upstream extent of Brook Trout is limited primarily by physical obstructions such as waterfalls or cascades. Acidification may lead to chemical barriers that limit upstream movement during high flow in a few streams. As recovery from acid deposition begins, and as regional climate changes, our observations demonstrate the value of periodic evaluations documenting shifts in the distribution and composition of fish communities in headwaters of the northeastern US.
Algal community composition at three sites above and five sites below Lock and Dam 19 on the upper Mississippi River was determined from samples taken during July, August, September, and November of 2003, and April and June of 2004, to compare the above-dam navigation-channel and vegetation-bed phytoplankton communities, and determine what effect the power plant and lock and dam may have on the mixing of these communities. We predicted there would be clear differences in community composition and abundance between the three above-dam locations and a more uniform community composition below the dam due to mixing. No site-specific or predictable patterns to suggest an effect of the power plant or lock and dam were detected. Nonmetric multidimensional scaling ordination supports the idea that temporal factors may play a larger role in structuring localized phytoplankton communities in this section of the upper Mississippi River.
Cyanobacteria blooms have long been described for Chesapeake Bay nontidal and tidal waters, but measurable toxin has only been recently recorded. During September 2000, the earliest tidal-water records of cyanotoxins in the Bay identified microcystin from a Microcystis-dominated bloom on the Sassafras River. Between 2000 and 2006, opportunistic samples collected from cyanobacteria blooms were analyzed for toxin concentration to better inform natural resource, agriculture, and human-health management agencies on potential bloom-related health risks. The hepatotoxin microcystin was detected most frequently and over a range of concentrations from 2.9 × 10−2 to 6.58 × 102 μg L−1. Microcystin levels exceeded literature-based chronic drinking-water guidance values of 1 μg L−1 and recreational safety guidance for children of 10 μg L−1 in 71% and 31% of samples, respectively. Samples from tidal fresh and oligohaline habitats showed a log-normal distribution of toxin concentrations, and microcystin had positive log-linear relationship with Microcystis aeruginosa cell counts (r2 = 0.42). A subset of the samples positive for microcystin was also tested for neurotoxins and showed anatoxin-a as the next-most common toxin encountered (46% of samples tested) at concentrations from 3 × 10−3 to 3 μg L−1. Saxitoxin (PSP-toxin) was present in trace amounts (3 × 10−3 μg L−1) in one sample. Cylindrospermopsis raciborskii has occasionally been found in abundance, but all tests for cylindrospermopsin were negative. Microcystin and anatoxin-a have been identified in association with fish kills, bird kills, and human-health events. Virginia and Maryland state management agencies conducted beach closures during 2000, 2003, and 2004 and provided waterway health advisories in 2005 and 2006 in response to the findings.
Demographic information from geographically isolated conspecific populations is important for understanding how a species is locally adapted, and can thus inform conservation decisions. Clemmys guttata (Spotted Turtle) is declining throughout its range in eastern North America due to habitat loss and fragmentation and collection of specimens for the pet trade. The objectives of our study were to describe the demography of a previously unstudied island population of Spotted Turtles and to make comparisons to conspecific mainland populations. We conducted mark-recapture surveys for turtles on a small (23.2-ha) island in eastern Georgian Bay, ON, Canada. Over seven sampling trips, 40 different turtles were captured 72 times: 23 females, 6 males, 10 juveniles, and 1 hatchling. Males had significantly larger straight-line carapace lengths and contour carapace lengths than females, whereas females had greater carapace heights than males. Adult females on the island were significantly smaller than females on the mainland. Density was estimated to be 1.7 turtles/ha for the entire island, and 21.4 turtles/ha in one wetland where turtles aggregated in spring. The adult sex ratio was significantly skewed in favor of females (1 male: 3.83 females). Our study provides information on the population ecology of Spotted Turtles in isolation, which is important for the creation of management plans for populations being fragmented by human activities.
Emydoidea blandingii (Blanding's Turtle) is a Species of Special Concern in New Hampshire, yet it has received little research attention. As part of a broader study to establish conservation and management guidelines for this species, we radio-tagged 18 Blanding's Turtles to determine home range and movement patterns within two study areas of southeastern and central New Hampshire from 2000–2002. Mean daily movement of female turtles peaked in June coincident with nesting, whereas movement of males peaked in August and September coincident with an increase in mating activity. Median adaptive kernel home range (HR) and core range (CR) estimates for turtles in central New Hampshire (HR = 12.5 ha, CR = 3.1 ha) were larger as compared to southeastern populations (HR = 3.7 ha, CR = 1.6 ha). This difference could not be readily explained by characteristics of the turtles, such as age, size, or sex. New Hampshire populations of Blanding's Turtles exhibit intermediate home range sizes compared to other parts of the species distribution. Forty-five percent of turtles exhibited multimodal location distributions in core range estimates. Mating and estivating turtles were always found within their core range area, whereas turtles occasionally traveled outside of core ranges to seek suitable overwintering sites. Thirty-eight percent of turtles used the same overwintering habitat for 2 consecutive winters. Location-specific information regarding key nesting and overwintering areas may be important to the conservation of the species.
Changes in land use and intensification of agricultural practices are associated with declines of grassland songbird populations in North America. Hay harvests in the northeastern United States are occurring earlier and more frequently today than 30 years ago, resulting in substantially decreased nesting success of grassland songbirds on early-hayed fields. Few studies have examined whether uncut patches within fields cut during the breeding season can increase the nesting success of grassland songbirds. Twenty-nine artificial nests were placed in 17 uncut patches (mean = 0.337 ha, median = 0.103 ha) on four early-hayed fields in Shelburne, VT. Only one of the 29 artificial nests was depredated. Despite the small sample size, these data suggest that minimal nest cover may allow some reproductive success during hay harvest. Investigating the effect of patch size variation, patch placement, and vegetation structure within uncut patches would prove useful for potential management strategies. While most farmers will be unable to find and cut around grassland songbird nests, larger uncut patches (i.e., ≥ 1 ha) encompassing areas with high avian nesting densities may be a useful management strategy for grassland birds in intensively managed hayfields of the Champlain Valley of Vermont and New York or similar dairy-dominated agricultural landscapes.
Many aspects of the ecology of Myotis leibii (Eastern Small-footed Myotis) are unknown due to the rarity of the species throughout its range in the eastern United States. Few studies have examined Eastern Small-footed Myotis migration and roosting behavior. Until a recent discovery of a population of Eastern Small-footed Myotis using an abandoned railroad tunnel in western Maryland, most observations from the state were limited to records of a few individuals at scattered caves, mines, and tunnels. We used harp traps to capture Eastern Small-footed Myotis at an abandoned railroad tunnel located in Allegany County, in spring 2007. We captured 47 Eastern Small-footed Myotis and equipped four females with radio transmitters. Telemetry revealed that female Eastern Small-footed Myotis migrated ≤ 1.1 km to nearby shale barrens and roosted in rock outcrops of various sizes during spring. Females moved <50 m between successive diurnal roosts, which did not differ from random sites located within the shale barrens in terms of site characteristics. Migratory distances and, consequently, geographic ranges of female Eastern Small-footed Myotis probably are influenced by the availability of hibernacula and roosting sites across the landscape.
The collection of an Agkistrodon piscivorus (Cottonmouth) on a barge in Winona, MN lends credence to the belief that this species may occasionally be carried up the Mississippi River via commercial boat traffic. Consideration is given to reports of other crotaline snakes not expected to occur in the upper Mississippi River drainage, including Agkistrodon contortrix(Copperhead), Crotalus viridis (Prairie Rattlesnake), and Crotalus atrox (Western Diamondback Rattlesnake).
The behavior of the marine dragonfly, Erythrodiplax berenice (Seaside Dragonlet), was studied over two summers at Weskeag Marsh, South Thomaston, ME. These dragonflies are lethargic, spending over 99% of their time perched on the culm of a salt marsh plant. No evidence of territorial behavior was found. Females oviposit while in tandem in algal mats on the surface of salt-water pannes. These dragonflies perch preferentially into the wind, presumably to aid in providing lift on take-off.
In order to assess the effect of bird feeders on the distribution of ticks on a residential lawn, ticks collected beneath bird feeders were compared to similar control areas on a residential property in Worcester County, MA. Host-seeking ticks were sampled from August 8, 2005 to July 25, 2007 by dragging with white flannel cloth. All ticks were counted and removed from the cloth. Sampling was conducted 38 times. A total of 12 ticks (larvae and nymphs) was collected. Significantly more ticks were collected from under the bird feeders (n = 10) than the control areas (n = 2).