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Collections of caddisflies from a riparian wetland associated with Tomah Stream (Washington County, ME) have revealed a rich assemblage of 148 species, comprising approximately one-half of all species known from Maine. This wetland is the only location documented in Maine for 11 species of caddisflies. Seven of these are widely distributed throughout northeastern North America, and their occurrence in Maine is not surprising. Records for four species, however, represent northeastward range extensions of 700–1500 km, and one species, a member of the microcaddisfly genus Hydroptila, is new to science. The high species richness of caddisflies documented in this study, combined with the presence of potentially isolated populations of several species with predominantly southern distributions, suggests that the Tomah Stream wetland may be a hotspot for freshwater invertebrate diversity in Maine. Current knowledge, however, is not sufficient to allow conclusions about whether the level of species richness demonstrated in this study is a local-scale phenomenon or one that should generally be expected for riparian wetlands in northeastern North America.
Understory vegetation of 17 clearcuts 1 to 26 years old and three mature secondary forests in Garrett County, Maryland was sampled during the summer to investigate species composition and abundance during forest regeneration. Canonical correspondence analysis (CCA) was used to determine which measured environmental variables (EVs) were significantly related to species distributions among the sites and to characterize species abundances along these environmental gradients. Stand age and site moisture were the most important EVs related to species distributions. Biplots of EV vectors and species scores indicated early successional and shade-associated species (e.g. Rubus spp. and Arisaema triphyllum, respectively) that were most abundant in recent clearcuts (<10 yr old) and shade-associated species that were most abundant in older clearcuts and mature stands. Early successional species declined or disappeared as regenerating tree canopies started to close. Species distributions were significantly related to site moisture despite the broad range of light availability associated with differences in stand age and overstory basal area among the study sites.
Ozone is a secondary air pollutant formed under conditions of bright sunlight and warm temperatures as a result of photochemical reactions involving nitrogen oxides and hydrocarbons as primary precursor pollutants. Tropospheric ozone is of regional-scale importance due to long-range transport of polluted air masses from urban and industrial areas of the Midwest and Northeast into agricultural and forested regions situated downwind of these expansive source regions. Ozone is perhaps the most important air pollutant of concern to the long-term productivity and health of trees and other native plants which comprise our natural and forested areas of the Northeast. On broadleaf species, foliar injury is exhibited as a stipple and/or more general pigmentation of the upper leaf surface late in the growing season. These symptoms are considered to be the best response parameter to observe and relate to ambient ozone exposures; ozone-induced injuries on conifers are more difficult to diagnose. Several plant species are known as bioindicators of ozone exposures; symptom observations from a recent open-top chamber investigation in central Pennsylvania confirm black cherry, yellow poplar, white ash, common milkweed, spreading dogbane, and blackberry to be sensitive to ambient ozone exposures. Concerns for lack of ozone air pollution monitoring in remote forested areas and more complete understanding of the effects to tree species and other native plants are discussed.
Four species of non-native coccinellids in North America have expanded their ranges to include Cape Breton Island, Nova Scotia in the past 20 years. Lady beetles were sampled in 1998 at five sites in industrial Cape Breton to determine the status of these four non-native species. Coccinella septempunctata L. has been established for about 15 years and was the most common coccinellid in Cape Breton during the past 10 years. It continues to be one of the most common and widespread species. The other three are very recent, mid-1990s, introductions to this area. Harmonia axyridis (Pallas) has apparently not become established. Two others, Propyleaquatuordeci-mpunctata (L.) and Hippodamia (Adonia) variegata (Goeze), are now common and widespread. The latter is particularly abundant, especially in the late summer. Native species were rarely encountered; the most frequent, Coccinella trifasciata, made up less than 4% of all individuals. During the past ten years, Adalia bipunctata L. has been the most abundant native species. However, only two individuals were observed during 40 hours of sampling in 1998, possibly indicating a major decline.
The range of brook silverside (Labidesthes sicculus) extends from Minnesota eastward to southern Quebec, and south through New York, Texas, and Florida. The species is found in the St. Lawrence and Richelieu Rivers in Quebec, and the Allegheny and St. Lawrence River drainages, Mohawk and Hudson Rivers in New York. We found brook silverside for the first time in four of the five basins of Lake Champlain, over a range of 150 km, in 1998. Several individuals were collected at each site, indicating that the species is established in the lake. The route of introduction of brook silverside is unclear; they could have entered the lake from the Mohawk River via the Champlain Canal at the south end or from the Richelieu River via the Chambly Canal at the north end. This finding extends the range of brook silverside by approximately 88 km, into Lake Champlain in western Vermont.
We monitored amphibian movements from 5 March to 11 October 1998 at a 0.16 ha seasonally flooded pond in southern Rhode Island. We documented 5,122 capture events representing six species of anurans and four species of caudates. Using mark-recapture models, we estimated breeding population sizes [e.g., 181 adult spotted salamanders (Ambytoma maculatum) and 753 adult wood frogs (Rana sylvatica)] and densities (1,131 adult A. maculatum per ha and 4,706 adult R. sylvatica per ha) for five species. Amphibians were captured every month the pond was monitored. Adults primarily immigrated to the pond from early March through May, with peak numbers during March and April. Juveniles departed the pond from June through September, with most individuals emigrating in July and August.
Short-fringed or tyrol knapweed, Centaurea dubia (Asteraceae) is an invasive plant of fields and roadsides in the eastern United States. Insects from the plant's native Eurasian range have been introduced into North America in an attempt to control the spread of related Centaurea species. One of these biological control agents, Urophora quadrifasciata (Diptera: Tephritidae), a picture-winged seed-head fly, has dispersed throughout northeastern North America. This study examined the response of this seed-head fly to a nontarget host's (C. dubia) patch characteristics and seed production in an old field. Ninety percent of all stems contained at least one seed-head attacked by U. quadrifasciata and 59% of C. dubia seed-heads were infested. Neither location in the field, plant height, nor number of stems per patch influenced U. quadrifasciata numbers within seed-heads. Number of seeds per seed-head was influenced by location and patch size but not stem height.
Thirty-nine moss species occur on Kent Island, New Brunswick. Two-thirds of the moss species found on the island have mainly boreal ranges, which reflects the cool growing season and generally boreal character of the Bay of Fundy's vegetation. One species, Rhytidiadelphus loreus, has been recorded only once previously in the province. Most moss species showed distinctive habitat distributions. Percent cover of the 12 commonest species was highest in spruce-fir forest and lowest in mountain ash stands. Sporophyte production was relatively low in all species and varied between habitats. Sporophytes were observed in fewer than 1% of 25 x 25 cm quadrats during the months of June and July. The low species richness of mosses on Kent Island relative to mainland habitats is presumably due to the island's small size, isolation from the mainland, low elevation, relatively simple plant community, and harsh physical environment.
Seal interference with Atlantic Salmon (Salmo salar) aquaculture cages is a financial burden to the industry. Harbor seals (Phoca vitulina) on haul-out sites along portions of the New Brunswick coastline of the Bay of Fundy, Canada, were counted during the autumn and early winter of 1998. Semi-monthly aerial and shipboard surveys were conducted when low tide occurred in the afternoon. The maximum number of seals counted (1032) and the rate of population decline (6.7 per day) were similar to those reported in 1984 and 1987. The average number of seals per group (35.8 ± 39.9) did not change over the season but fewer groups occurred in early winter. The seals vacated some areas which coincidentally contained Atlantic salmon aquaculture cage sites. Similar movements were observed 11 and 14 years previously, before the cage sites were established. Harbor seals are not attracted to areas containing aquaculture cage sites.
Turkey Vultures (Cathartes aura) and Black Vultures (Coragyps atratus) were observed at a day perch in south-central Pennsylvania during winter of 1984–85 to determine whether there were species-specific differences in behavior that could be correlated with microclimatic variables. Multiple linear regression analysis was used to relate behavior at the day perch to wind speed, solar radiation, and air temperature. Turkey Vultures arrived earlier at the day perch and moved more predictably than did Black Vultures from high branches to a fence or to the ground as solar radiation and wind speed rose. Although neither species made adjustments in solar orientation to changing conditions, the Turkey Vulture predictably demonstrated wing-spreading behavior in conjunction with high solar radiation.