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Unambiguous species identification is fundamental, especially when attempting to study species-specific interactions or management and conservation issues. Current weasel identification methods are based on external and cranial morphology, yet North American weasels show significant geographic variation in size and considerable overlap occurs in measurements of Mustela erminea and M. frenata. As a result, these species can easily be confused. Our objectives were to : (1) develop a simple method based on restriction fragment length polymorphism (RFLP) analyses to classify Mustela spp. in eastern Québec, Canada; (2) validate existing external and cranial morphological criteria in the literature for weasel identification; and (3) calculate discriminant functions based on genetically identified specimens to aid in Mustela identification where genetic laboratory facilities are not readily available. Skeletal and external measurements were taken on adult male Mustela specimens (n = 28) that had been collected in the winter of 2002–2003. Results from genetic analyses confirmed a northern range expansion of long-tailed weasels into Québec and revealed that current morphological criteria alone are not adequate for classifying Mustela specimens. As many as 18% of Mustela erminea and M. frenata individuals were mis-identified due to morphological measurements, either falling outside known ranges for each species or inside measurement ranges common to both species.
European settlement of New England initiated a novel disturbance regime that was prolonged, intensifying through time, and spatially widespread. By the mid-20th century, human commercial and industrial activities had brought about the ecological collapse of several major rivers. Since the mid-1970s, river ecosystems have recovered substantially in response to primary treatment of industrial and municipal wastewaters mandated by the Clean Water Act of 1972. Here we reconstruct an environmental history of a river-estuary complex in mid-coast Maine to examine ecosystem degradation and collapse during three centuries of intensified human disturbance followed by ecosystem recovery over the three decades since the Clean Water Act and the ban on the general use of DDT pesticide in 1972.
Merrymeeting Bay is a large, freshwater tidal ecosystem formed by the confluence of six rivers, 30 km inland from Maine's Atlantic coast. It was once a major stopover for migrating waterfowl and provided vital spawning and nursery habitat for anadromous fish. However, human activities—beginning with overfishing, land clearance, and dam building in the 18th century and culminating in severe industrial and municipal pollution in the 20th century—fully degraded this important ecosystem. By the mid-20th century, summer dissolved oxygen concentrations were routinely depleted resulting in vast fish kills, and poisoning from DDT pesticide eliminated reproduction of Bald Eagles. Since primary treatment facilities began operation and the DDT ban went into effect, dissolved oxygen concentrations have generally been maintained above dangerously low levels, and reproduction has recovered in Bald Eagles and some species of anadromous fish. These improvements notwithstanding, the legacies of past human disturbance continue to impact this important ecosystem. Merrymeeting Bay is permanently shallower, its anadromous fish runs are vestiges of their former abundances, toxic substances remain in its biota and sediments, and it continues to receive excess nutrients from industrial and municipal sources. These legacies are varied and profound. Whereas some physical, chemical, and biological properties recovered rapidly with cessation of the disturbance, others will require considerable more time or may never fully recover.
A common garden experiment was used to test for genetic differentiation between populations of the widespread Mimulus ringens var. ringens and the very locally distributed var. colpophilus, in and around Merrymeeting Bay in Maine. Measurements in the field documented a statistical difference for leaf length and calyx lobe length between populations found in non-tidal versus tidal waters, although most populations surveyed fell within values originally established for var. ringens. Field-collected seeds grown in the greenhouse showed differentiation between varieties for flowering date and for three of four of the morphological characters measured. A second generation grown in the greenhouse showed differentiation between varieties for the same three morphological characters, but not for flowering date.
Negative impacts of Phragmites australis expansion in tidal marshes along the Atlantic coast of North America have spurred numerous efforts to eradicate this invader. Nonetheless, Phragmites-dominated marshes may have considerable habitat value, and few studies have examined the short-term effects of various Phragmites-control treatments on resident animals. The present study addresses the impacts of herbicide (Rodeo) spraying and rotary mowing of Phragmites upon the use of the marsh surface by macroinvertebrates and fishes within a few months of treatment. During spring tides in July, August, and September of 2002, fishes and crustaceans leaving flooded marsh areas along the Lieutenant River, a lower Connecticut River tributary, were captured with Breder traps at 30 sites equally distributed among treated Phragmites, untreated Phragmites, and Typha angustifolia marsh areas. Macroinvertebrates were collected in the three types of marsh using litter bags and shallow pit traps placed along transects normal to the river bank. Treatment produced large mats of Phragmites litter which were gradually removed from the marsh surface, but more rapidly near the river bank than farther into the marsh interior. Macroinvertebrates sampled by both methods were as abundant in treated areas as in untreated Phragmites. Fish and crustacean assemblages in the different types of marsh were similar. Overall, the numbers of Fundulus heteroclitus, the dominant fish species, were not significantly different among treated, untreated, and Typha marshes. This fish foraged extensively, and its diets were similar in all three marsh areas. Herbicide treatment and mowing of Phragmites appeared to have no major impact upon macroinvertebrate and fish use of the marsh during the following few months.
The Eurasian Lythrum salicaria is invading wetlands throughout North America. Our study sought to (1) document the extent of L. salicaria invasion along the lower West Branch of the Susquehanna River in central Pennsylvania and (2) assess the correlates of L. salicaria abundance including associated species and environmental/edaphic characteristics. We documented that L. salicaria is well established on the West Branch of the Susquehanna River, but only in that portion within the Ridge and Valley Province. Multiple analyses indicated that L. salicaria is associated with open-canopied, hydric sites with nutrient-rich, clay and/or silt soils. The vulnerability of a West Branch site to invasion by L. salicaria is best assessed by the presence of plant associates including Eleocharis obtusa, Phalaris arundinacea, and others.
Seed banks of Aeschynomene virginica may have significant implications for population dynamics and conservation of this rare, freshwater wetland, annual plant. Little work, however, has been done on the size and extent of the seed bank of this threatened plant. Experimental seed banks were placed at three sites to estimate overwinter seed survivorship and the potential for long-term seed dormancy. The soil beneath 5 extant populations was sampled after current-year seed germination and before seed fall to determine the presence and spatial distribution of seeds surviving more than one season. An average of 47.4 ± 2.8 (± 1 SE) of the 125 seeds placed in the field survived over winter. Of those seeds that were recovered from experimental seed banks, an average of 37.3 ± 1.7 germinated under greenhouse conditions. When the seed coats of ungerminated seeds recovered from experimental seed banks (10.3 ± 0.3) were scored, 4.9 ± 0.8 seeds germinated. Analysis of soil cores from the field showed high variability in natural seed distribution. Significantly more potentially viable seeds were found in plots with standing A. virginica plants than in those with no standing plants. Results indicate that A. virginica forms a Type III seed bank. The seeds in a seed bank may augment population size following poor seed production years, or they may reestablish locally extinct A. virginica populations.
The status of the mussel community of Ohio Brush Creek and its tributaries in southeastern Ohio was evaluated over a 17-year period. Species richness increased from 16 and 20 species found in 1996 and 1987, respectively, to 23 found in 2004. Despite the increase in species richness, the abundance of live and freshly dead shells declined, particularly for common species. Community structure changed from one dominated by a few abundant species to a more evenly distributed community composed of a greater number of species with lower abundances. Further work is needed to determine if changes in abundance are due to mortality, lack of recruitment, or are simply a reflection of variability in population size and sampling.
The exotic shrub Lonicera tatarica (Tartarian honeysuckle) has aggressively invaded woodlands and forests in central and eastern North America; however, its impacts on native plant species are not well understood. We used a greenhouse seedling experiment to examine the effects of L. tatarica on Quercus alba (white oak), the presettlement dominant tree of many of these forests. Growth-related parameters of Q. alba seedlings (height and basal diameter increases, biomass) did not differ between treatments when grown in monoculture or with L. tatarica competitors. In addition, when paired with native Cornus (dogwood) species, Q. alba displayed similar growth as when paired with L. tatarica. Quercus alba also did not respond differently to native and L. tatarica competitors across a range of densities, although greater competitor diversity resulted in somewhat lower height growth than other treatments. Due to the similarity in Q. alba growth across native and exotic shrub combinations, we argue that seedling-to-seedling competition with Q. alba is not a significant impact of L. tatarica invasion.
Cattle production is a common land use, and the adverse effects of cattle grazing on stream habitat and macroinvertebrates has been well documented. The purpose of our study was to provide a list of taxa that can be expected to occur in small streams impacted by cattle in the southern Blue Ridge Mountains and to demonstrate how taxon-specific natural history information can be used to gain insight about benthic habitat condition. We identified 97 benthic macroinvertebrate taxa from five cattle-impacted streams that differed in cattle grazing intensity. Our findings suggest that some macroinvertebrate taxa can sustain low levels of cattle grazing and that sedimentation is a major stressor to the macroinvertebrate fauna.
We note the first records of non-native Umbra limi (Umbridae; central mudminnow) in Maine. Unrecognized fish were captured in minnow traps set in Caribou Bog, in the town of Orono, during the summer of 1999. Preliminary identification by gross anatomy, coloration, and markings indicated that the fish were central mudminnow. We later confirmed this field identification using standard measurements and counts; specimens were vouchered (CU82322). Streams within Caribou Bog were resampled for central mudminnow during the summers of 2000 and 2002. Several size classes were captured, indicating the presence of viable populations. A single central mudminnow was also collected from the St. John River in northern Maine during the summer of 2005. Further sampling is warranted to determine the actual extent of central mudminnow distribution in Maine.
The first pelecinid wasp in Cretaceous amber is described and figured from a single male preserved in Turonian (ca. 90 Ma) amber from New Jersey. Henopelecinus pygmaeus, new genus and new species, is most notable for its minute body size (ca. 6.5 mm) and unexpanded sixth metasomal segment. The fossil is compared to other genera of Pelecinidae including those taxa of the controversial extinct “family” Iscopinidae.