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We used abundance data from fish-population studies (1962–2010) on Otter Creek at Markle's Dam, Vigo County, IN, to examine temporal variation in stream-fish assemblages. Species-richness variation showed a declining trend during the 50 year study period with a mean of 49 ± 8.8 species per decade (range = 39–62 species). Cumulative study species richness comprised 76 fish species with a mean of 21.3 ± 6.1 species collected per sampling event. Dominant species, based on relative abundance during the 50 year period, included Cyprinella spiloptera (Spotfin Shiner), Pimephales notatus (Bluntnose Minnow), Hybognathus nuchalis (Mississippi Silvery Minnow), and Luxilus chrysocephalus (Striped Shiner). Relative abundance of Spotfin Shiner showed an increasing trend during the 50-year study period, whereas Bluntnose Minnow relative abundance showed a decreasing trend. Cumulative frequency-distribution of species richness normalized by decade showed no significant difference, with the exception of the 1970s, which showed a steep decline in the number of species. Repeated-measures analysis of variance showed no significant differences in species diversity (H') or evenness (Pielou's J) over the 5-decade study period. Eleven cool-water species including Chrosomus erythrogaster (Southern Redbelly Dace), Perca flavescens (Yellow Perch), Catostomus commersonii (White Sucker), and Ambloplites rupestris (Rock Bass), and lithophilic spawning species such as Nocomis micropogon (River Chub) and Hybopsis amblops (Bigeye Chub) were extirpated during the study period. Potential changes in sedimentation and thermal gradients may have contributed to these observed extirpations.
Dual-frequency identification sonar (DIDSON) offers important advantages over other sampling tools for observing pelagic and benthic fishes in situ. Because it relies on sound, DIDSON can detect fish in a non-destructive and non-intrusive manner. In our unique application, the equipment's small size and low power requirements allow deployment from a kayak for increased maneuverability in complex habitats. Characteristics that typify echograms of different fishes can be extracted using multivariate ordination techniques, such as principal components analysis (PCA), with in situ groundtruthing. Here we present reference images, techniques, and human-observer-error estimates from DIDSON application. Together, these approaches enhance our ability to sample fishes and even observe certain behaviors in complex, turbid environments during a full diel cycle.
The goal of this study was to obtain information on diversity, abundance, and distribution of non-volant small mammals in 4 major habitat types in each of 5 regions of Ohio. We trapped in 31 study areas, representing 39 counties, for 3 consecutive nights for a total of 38,400 trap nights. We established eight 100-m transects (each with 10 live traps, 20 snap traps, and 20 pitfall traps) per study area in woodland, oldfield, grassland-pasture, or restored prairie-wetland habitats. We captured fourteen species of small mammals (shrews and rodents <100 g in body mass), but 97% of the 2150 captured consisted of just 4 species: Microtus pennsylvanicus (Meadow Vole; 31%), Peromyscus leucopus (White-footed Mouse; 29%), Blarina brevicauda (Short-tailed Shrew; 21%), and Sorex cinereus (Masked Shrew; 16%). Regional differences in abundance of small mammals (captures/100 trap nights) and species diversity (H') were not significant (P > 0.05). Seven species of interest were captured in low numbers (<10) and 2 others, Reithrodontomys humulis (Eastern Harvest Mouse) and Myodes gapperi (Red-backed Vole), were not captured in the course of the 2-year study.
Rainfall patterns are becoming more extreme in the northeastern US and are expected to intensify with an increase in extreme precipitation events and a greater frequency of short-term drought. In Northwest Bay, an undeveloped, primarily forested sub-watershed of Lake George, NY, stream discharge and phosphorus loading in 2006 exceeded that of 2007 by more than 3-fold due to unusually heavy rainfall in 2006 and below average rainfall in 2007. The additional phosphorus loading to the open water positively influenced chlorophyll concentrations in 2006, while porewater soluble phosphorus significantly correlated to precipitation in both 2006 and 2007. The elevated porewater concentrations in early summer of 2006 provided a nutrient advantage that resulted in tissue phosphorus in 3 macrophyte species to more than double while no change in nitrogen or carbon was detected. It is believed that the heavy late spring/early summer rainfall in 2006 saturated soils creating additional stormwater run-off and increasing groundwater seepage that supplied ample phosphorus resulting in enhanced phytoplankton biomass and macrophyte uptake of phosphorus.
Thermal data were collected from 15 of 16 species of snakes found at the Mason Neck National Wildlife Refuge, Fairfax County, VA. Data recorded at each capture included the date, 24-hour military time, body temperature (BT), air temperature (AT), ground-surface temperature (ST), water temperature (WT) if in water, and the snake's activity (under cover, moving on land, basking, foraging, climbing, swimming, courting/mating). The purpose of this study was to determine the potential range of operating body temperature (OBT) of the individual species. The range of OBT is interpreted as the snake's operating temperature at its current environmental temperatures (ET), which can be used in comparisons with similar data from other North American regions, and represents the first such report from the Mid-Atlantic Region. The mean and ranges of BT, AT, ST, and WT are presented for the eight snakes with 20 or more records: Carphophis amoenus (n = 238), Coluber constrictor (204), Nerodia sipedon (67), Thamnophis sirtalis (55), Diadophis punctatus (54), Pantherophis alleghaniensis (43), Thamnophis sauritus (26), and Agkistrodon contortrix (24). New thermal records are reported for several of these species. The ranges of BT during activities are also reported. New temperature records are also reported for Virginia valeriae (n = 16 encounters), Storeria dekayi (12), Opheodrys aestivus (6), Lampropeltis calligaster (6), and Regina septemvittata (2).
Bat mortality caused by terrestrial wind-power plants has been documented and offshore wind-power developments may have similar effects. Determining which bat species occur offshore, how far they range from shore, and predictors of high activity may be helpful to developers and wildlife managers. We studied bat activity off the mid-Atlantic coast, using ultrasonic detectors mounted on ships in spring and fall 2009 and 2010. We investigated the association between nightly bat activity and weather variables, including wind speed, air temperature, and barometric pressure. Echolocation passes of bats totaled 166; maximum detection distance from shore was 21.9 km, and mean distance was 8.4 km. Most passes were identifıed as Lasiurnis borealis (Eastern Red Bats), representing 78% of bats identifıed to species or species group. Bat activity decreased as wind speed increased, but activity did not differ with distance from shore. Offshore wind projects proposed for locations beyond the maximum detection distances noted in our study would likely have few impacts on seasonal movements; however, depending on their location and operating protocols, projects closer to shore could result in fatalities similar to those reported at onshore wind facilities.
To better understand and compare regional habitat characteristics for the endangered Charadrius melodus (Piping Plover) in the Canadian Maritime provinces, we surveyed transects on nesting beaches along the Gulf of St. Lawrence and Atlantic coasts of the Canadian Maritime provinces. The beaches along the Gulf of St. Lawrence were flatter, were wider and had a higher proportion of mixed substrate than those on the Atlantic coast. While habitat use by breeding Piping Plovers was largely consistent with other studies, significant differences were found between the two regions. Piping Plovers along the Gulf of St. Lawrence were found nesting in flatter areas with a high proportion of mixed substrate and less wrack. On the Atlantic coast, Piping Plovers preferred wider and flatter sections of beach. Future conservation efforts aimed to maintain or increase populations should recognize the importance of fine-scale habitat characteristics in nest-site selection.
Catharus bicknelli (Bicknell's Thrush) is a rare and globally vulnerable songbird often found in regenerating clearcuts in the Canadian maritime provinces and Québec. Previous studies have shown correlations between vegetation characteristics and occurrence and abundance of this species, but no study has described vegetation associated with Bicknell's Thrush nests in managed forests. From 2007–2010, we investigated nest-habitat selection of Bicknell's Thrush in the industrial forestry landscape of north-central New Brunswick. We compared vegetation composition and structure in 5-m-radius patches around nests to vegetation in a random control-patch within the home range of each Bicknell's Thrush. Precommercial thinning (PCT) is a forest-management treatment that may reduce the suitability of habitat for Bicknell's Thrush, thus we also examined the percent of the landscape treated by this practice around Bicknell's Thrush nests. We found that Bicknell's Thrush preferentially selected nest sites with a significantly lower proportion of deciduous trees and higher overall tree density than randomly sampled habitat within their home range. We also found that an average of 44% of the area within 500 m of Bicknell's Thrush nests was treated by PCT, and most had been treated within 3–5 years of our study. We suggest that small patches of dense, Abies balsamea (Balsam Fir)-dominated forest within a thinned matrix may be sufficient to provide nesting sites for Bicknell's Thrush; however, it remains unclear if these areas support production of young or if they are population sinks. PCT could have serious negative consequences on Bicknell's Thrush breeding success and on the long-term survival of the species in Canada; thus, we encourage silviculture treatments that leave unthinned areas for nesting of Bicknell's Thrush in managed forests.
Over the past 40 years, the complex of coccinellid (lady beetle or ladybug) species in New York has undergone substantial changes. Primarily, these changes have involved the decline of native species and the increase and spread of adventive species. Species declines have proceeded to the extent that several native species were feared to be extirpated from New York. Here we report that two of these native species, Adalia bipunctata (Two-spotted Lady Beetle) and Coccinella novemnotata (Nine-spotted Lady Beetle), were rediscovered in New York, in 2009 and 2011, respectively, by volunteers and specialists working for the Lost Ladybug Project. We found that the current coccinellid complex in New York is significantly less diverse and has a significantly higher proportion of foreign species compared to the complex in the past. We discuss the potential causes and implications for these shifts and rediscoveries.
The objective of this study was to collect and document the vascular plant species at the 2236-ha Brookhaven National Laboratory. We made collecting trips at 2-week intervals from April 2007 to October 2009 during which we identified 320 species in 226 genera in 98 families. The Asteraceae (45 species) and Cyperaceae (24 species) were the most commonly collected families. The most diverse genera were Carex spp. (sedges) and Quercus (oaks) with 11 and 9 species, respectively. One hundred eight species, 34% of the flora, were non-native taxa. We observed 2 rare taxa at the study site: Lespedeza angustifolia (Narrowleaf Lespedeza) and Rhynchospora scirpoides (Longbeak Beaksedge).
Urbanization results in a suite of harmful effects to streams, including removal or degradation of riparian vegetation. Many stream-restoration programs address this by adding plants, with limited quantitative knowledge about vegetation dynamics already occurring within the stream corridor. This project examined natural plant establishment along an urbanized stream channel in Syracuse, NY. It had three objectives: first, to relate plant establishment along an urban stream gradient to substrate condition; second, to quantify seeds dormant in the soil at those same sites; and third, to indicate what passive revegetation responses might occur to various treatments along a rural-to-urban gradient. Three sites were selected along such a gradient on Onondaga Creek, near Syracuse, NY. Vegetation plots were established at each site to assess plant germination and establishment under substrate conditions designed to mimic restoration interventions. We also conducted a seedbank study using soil cores collected from these sites. Plant communities were dominated by grasses and forbs. Numbers of alien species increased from 34% at more rural sites to 51% at more urban sites. Seedlings of native riparian trees nonetheless germinated at all three sites along the gradient. Recruitment of native riparian trees (especially Populus deltoides [Eastern Cottonwood], Fraxinus pennsylvanica [Green Ash], and Acer negundo [Boxelder]) exceeded non-native and invasive ones. The riparian seedbank showed disproportionate dominance by herbaceous plants (95.5% of individuals) at all locations surveyed, and invasive species were common (about 25% of all germinants). This study shows some potential for natural regeneration of native trees, but also found a significant source of invasive plants in the soil seedbank that could reduce restoration success. Notably, the study recorded the presence of 16 bryophyte taxa, and the common ones were those typically associated with disturbances.
Understanding causes of mortality in a population provides information about the selection pressures acting on individuals in that population. To obtain unbiased estimates of mortality, researchers must track individual animals until they die, retrieve dead animals, and make a forensic estimation to determine the cause. Given the limitations of traditional radio-tracking technology and the biases inherent in other methods of estimating mortality causes, little is known about causes of mortality in small mammals (<1 kg). Here we used an automated radio telemetry system to record activity patterns and detect mortality events in a wild population of Peromyscus leucopus (White-footed Mouse). Mice (n = 32) were fitted with small (1 g) radio-collars. Daily survival rate was 0.98 ± 0.01, which translates to a 50% chance of survival over a 29-day period. Although the species is well known as a vector for various diseases, we found only one death attributable to disease. Most mouse mortality (93%) was caused by predators, primarily Mustela spp. (weasels ). We found a significant relationship between Borrelia infection (the bacterium that causes Lyme disease in humans), and increased mortality (χ2 = 6.92, df = 1, P = 0.008); there was no detectable effect of sex on survival. Our results suggest that, to the extent that predation risk is dependent on heritable phenotypes, predation risk is the most important evolutionary force acting on mortality in the population we studied.