Orconectes rusticus (Rusty Crayfish) have invaded streams of the upper Susquehanna River catchment, NY, replacing native crayfish and, in some areas, increasing overall crayfish density. Crayfish are important consumers and significant agents of disturbance in aquatic communities, so the introduction and expansion of Rusty Crayfish could affect the invaded community through the change in crayfish species composition, the increase in crayfish density, or some combination of the two. Other macroinvertebrates are prey of, competitors with, or subject to disturbance by crayfish and so are likely to be affected by changes in the crayfish assemblage. I conducted experiments in stream enclosures to determine the effects of crayfish species and density on the macroinvertebrate community. Increasing crayfish density reduced macroinvertebrate density but did not significantly affect macroinvertebrate taxon richness, diversity, or community composition. At moderate densities, the effects of native O. propinquus (Clearwater Crayfish) and invasive Rusty Crayfish did not differ significantly, although experimental power to detect small differences was low. These results suggest that the invasion of Upper Susquehanna River catchment streams by Rusty Crayfish will impact the macroinvertebrate community most strongly where or when Rusty Crayfish achieve high densities.

Historically, Polyodon spathula (American Paddlefish) occurred within the Mississippi River Basin's large rivers, traversing hundreds of kilometers to complete their life cycle. However, populations declined in response to the installation of lock and dam (L/D) structures, declining water quality, and the loosely regulated harvest of the species. By the late 1800s, American Paddlefish were extirpated from many portions of their historic range. In response, federal and state agencies sought to restore inter-jurisdictional populations of this fish. Our objective was to assess reintroduction efforts in the northeastern-most portion of its range. Using a combination of gill nets, boat electrofishing, and larval drift nets, populations were sampled in Pennsylvania and New York over a 10-year-period, post-stocking. Although American Paddlefish were at large in navigable waters of the upper Ohio River Basin, free-flowing and tail-water areas below L/D structures appeared to hold more fish than impounded reaches. The presence of L/D structures and fixed-crest dams may inhibit upstream passage of fish and reduce the availability of forage, as reflected in reduced condition-index scores. Although gravid fishes were captured in Pennsylvania and New York, little evidence exists to suggest the presence of self-sustaining populations, as only one larval American Paddlefish was captured. The recovery of this species to its historic northeast range may hinge on continuing stocking efforts, development of fish-passage structures, conservation lockages, and improvement and protection of suitable spawning habitats.

Quercus (oak) regeneration failure threatens many forest and savanna communities worldwide, where preservation of vegetation structure and composition depends on acorns germinating and surviving into adulthood. However, predation on the acorns and browsing of seedlings limits oak regeneration. To better understand the effects of these 2 mechanisms on oak recruitment in the endangered Bluegrass savanna—woodland of Kentucky, we compared seed predation and herbivory on Quercus muehlenbergii (Chinquapin Oak) with Carya laciniosa (Shellbark Hickory), a successfully regenerating tree species. Compared to hickory nuts, acorns were predated more, cached less, and dispersed shorter distances. Neither the distribution of the seedlings under the parent canopy nor browse damage differed between the 2 species. Our results suggest that seed-predation prevents regeneration of oaks in this endangered community.

Researchers have reported that both Tachycineta bicolor (Tree Swallow) and Tachycineta thalassina (Violet-green Swallow) are more aggressive than Sialia sialis (Eastern Bluebird) and often outcompete bluebirds for nest sites. Therefore, we would not have expected that Tree Swallows would be victims of usurpation by Eastern Bluebirds. However, as part of a study on Tree Swallows, we found that although Tree Swallows occupied 68% of the nest boxes during May, there was also evidence of nest loss in Tree Swallows due to usurpation by Eastern Bluebirds. Suspected usurpation by Eastern Bluebirds resulted in the loss of 18% of Tree Swallow nests over 2 years. Almost all usurpation events coincided with the conclusion of the first nesting cycle in Eastern Bluebirds. Our data suggest that usurpation by Eastern Bluebirds is more common than reported in the literature.

This study examined climate—tree growth relationships of a G2 globally rare Pinus rigida (Pitch Pine) barren located at the species' northern range limit in Acadia National Park, ME. Our tree-ring chronologies spanned the period 1804–2014 CE and included 50 dated tree-ring series from 33 trees. We found significant (P < 0.05) positive correlations in all chronologies between each year's tree growth and previous October through April temperature, as well as with August precipitation. Additionally, we found negative correlations between our chronologies and previous July precipitation. Moving interval correlation analysis showed temporal instability of all climate—growth relationships except for April temperature and August precipitation for the total width and latewood chronologies. Our results corroborate previous findings that suggest tree species at their northern range limit respond positively to winter temperature. We posit warmer winter temperatures and enhanced late-summer precipitation indicate a maritime influence that positively influenced radial growth at our site.

Surveys of Odonata were carried out at Mass Audubon wildlife sanctuaries in all regions of the state and in multiple habitats. Our goals were to provide a comprehensive look at patterns of species distribution and relative species richness across Massachusetts and compare surveys where effort was and was not controlled. Observers encountered a total of 146 species, 11 of which were very widespread, having been recorded at more than 40 of the 54 properties examined. Thirty-five species were relatively rare, occurring at only 1 or 2 sanctuaries. A few sanctuaries were particularly notable for supporting somewhat uncommon species. These sites were not located in any particular ecoregion, but reflected local conditions. In surveys where effort was not controlled, a regression analysis indicated that about two thirds of the variation in species richness among sanctuaries could be explained by the amount of observer effort, the size of the sanctuary, and the extent of wetland habitat. Quantitative surveys that used transects or point counts to control for sampling effort resulted in observation of fewer species, including state-listed taxa, compared to the non-quantitative surveys. Despite producing fewer species, data from these quantitative surveys can be used to make statistical comparisons with data from future studies and detect changes over time in species richness, abundance, and frequency of occurrence.

Ostracods of the family Entocytheridae are obligate ectosymbionts, primarily of crayfishes. Although the distribution and diversity of crayfishes is well known in the northeastern US, little is known about entocytherids in this region. In this study, we examined 5 species of crayfishes—Procambarus acutus (White River Crayfish), Orconectes limosus (Spinycheek Crayfish), Orconectes propinquus (Northern Clearwater Crayfish), Cambarus bartonii (Common Crayfish), and Cambarus robustus (Big Water Crayfish)—from 3 counties in New York (Saratoga, Orange, and Tompkins) and 8 counties in New Jersey (Essex, Sussex, Atlantic, Burlington, Camden, Cumberland, Gloucester, and Ocean). We recovered 2 species of entocytherid ostracods: Donnaldsoncythere cayugaensis and Donnaldsoncythere donnaldsonensis. Records from our study expand the known range of D. cayuagensis and fill in gaps in the known range of D. donnaldsonensis.

Determination of the causes of water-impairment is a critical part of bioassessment, and it is useful to be able to infer causes from the same sampling data used to assess the impairment. Determination of excess nutrient inputs to a waterbody as a cause of impairment is especially important because of the severity and ubiquity of nutrient-related water-quality problems nationwide. To that end, we tested and validated in New Jersey waters a macroinvertebrate-based nutrient biotic index (NBI) for phosphorus and nitrogen developed by the New York State Department of Environmental Conservation (NYSDEC). We used macroinvertebrate, water-chemistry, and diatom data from New Jersey streams collected in the state biomonitoring program and a study of diatom—nutrient relationships. We calculated tolerance values for widespread taxa based on frequency of occurrence in samples from sites with a range of nutrient concentrations. The NBI of a sample was calculated as a sum of the tolerance values of taxa in a sample weighted by the relative abundances of taxa. We developed tolerance values from the New Jersey data because relatively few taxa present in the New Jersey samples were rated in the New York study. NBIs for the New Jersey data calculated using the New Jersey-based tolerance values were significantly related to nutrient concentrations with correlations similar to, or greater than, those observed in the New York study. For taxa in common, the New Jersey-based tolerance values were only weakly correlated with the analogous New York values. To validate the NBI approach, we calculated NBI scores via a “leave-one-out” procedure for a data set not used to estimate tolerance values. These comparisons yielded statistically significant but weak correlations between the NBIs and nutrient concentrations. Factors that weaken these relationships are related to: (1) the specific data used (e.g., the lack of tolerance values for many taxa in independent data sets and weak temporal matching of macroinvertebrate and nutrient samples), (2) estimation issues (e.g., variability in estimates of tolerance values and NBIs), and (3) problems inherent in the approach (e.g., the effects of other factors on macroinvertebrate relationships). However, for all data sets examined, nitrogen and phosphorus concentrations were positively correlated, as were nitrogen and phosphorus tolerance values for taxa, and nitrogen and phosphorus NBI scores for sites. These correlations need to be considered in the selection of sampling sites for the development of tolerance values, the weighting of taxa in calculation of NBIs, and the interpretation of NBI values for the 2 nutrients.

Tsuga canadensis (Eastern Hemlock) forests provide unique riparian zones that can influence adjacent streams, but increasing mortality from the invasive Adelges tsugae (Hemlock Woolly Adelgid) is eliminating this distinctive landscape component in some regions. The objective of this study was to determine if a stream section within a hemlock ravine harbored a unique benthic community as compared to other sections of the stream that could be threatened in the event of a Hemlock Woolly Adelgid outbreak. We sampled benthic algae and macroinvertebrates in an unnamed tributary of Sugar Creek within Beach City Wildlife Area, OH, in April and September 2015. The stream flows through 3 riparian habitats: beech—maple upland forest, hemlock ravine, and lowland forest dominated by Acer saccharinum (Silver Maple), A. negundo (Box Elder), and Platanus occidentalis (American Sycamore). Our results show that Chironomidae, Navicula, Caloneis, and Nitzschia were the dominant taxa across all 3 stream sections, but that benthic macroinvertebrate richness and density were significantly lower in the hemlock ravine when compared to the lowland habitat. Periphyton community metrics were not significantly affected by riparian habitat. Overall, seasonality was more influential than riparian habitat on benthic community composition; specific taxa were indicative of either the spring or summer season. Connectivity between stream sites and/or the abundance of sandstone bedrock substrate at many sample locations might account for the similarity in benthic communities across these 3 habitats.