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Aquatic insects are important components of stream food webs and are greatly impacted by anthropogenic disturbances, including urbanization. Successful restoration of urban rivers is contingent on the growth of aquatic insect populations from colonizers from local, less-disturbed streams. However, rivers in highly urbanized watersheds may not have nearby source populations, and therefore must rely only on individuals already surviving in the river. At the regional level, urbanization is a homogenizing process, but the impacts could be heterogeneous at the local level. Therefore, some sites within highly urban rivers might support higher local biodiversity and provide source populations for restoration projects focused on other sites in the river. In this study, we collected aquatic insects from sites within the Bronx River, a highly urbanized river in the New York City metropolitan area, NY, in the summers of 2021 and 2022. We found that while taxonomic richness was similar among sites, insect abundance and dominant taxa, particularly members of Hydropsychidae (Trichoptera), varied significantly among sites. These findings suggest sites within the Bronx River are not homogenous and that some sites within the river harbor larger populations of aquatic insects and may be integral to the success of future conservation projects. This pattern of within-river heterogeneity may exist in other urban rivers and deserves consideration in determining conservation goals and the planning of stream-restoration projects.
We collected data on the distribution of Balaenoptera physalus (Finback Whale), Balaenoptera acutorostrata (Minke Whale), and Megaptera novaeangliae (Humpback Whale), in the Quoddy region of the Bay of Fundy, Canada, from a whale-watching vessel during commercial tours from 2006 to 2012. Sightings were non-random between species and showed clumped distributions over the study area: Finback Whales (χ2 = 2454.03, df = 7, P < 0.005), Minke Whales (χ2 = 3488.24, df = 7, P < 0.005), and Humpback Whales (χ2 = 301.784, df = 7, P < 0.005). Minke Whales were most frequently sighted in Head Harbour Passage, high concentrations of Finback Whales were most frequently sighted off Blacks Harbour, and Humpback Whale sightings were highest around The Wolves. It appears that the whales aggregate in response to physical and biological features of the environment, such as depth, bottom topography, and fine-scale oceanographic features that enable foraging. Oceanographic features such as tidal state and temperature also influence the distribution of whales by aggregating their common prey species in high concentrations.
Hydrobates leucorhous (Leach's Storm-Petrel) are small, pelagic seabirds that breed at several large colonies around the coast of Newfoundland and Labrador, Canada, which support ∼5,000,000 breeding adults. The Northwest Atlantic population has declined by ∼54% from 1974 to 2018. A major conservation concern is the stranding of birds in brightly lit coastal towns. We used social media reports to map 5411 Leach's Storm-Petrel strandings across the island of Newfoundland from 1 May to 30 November 2021. Sites on the eastern Avalon Peninsula were stranding hotpots, and the peak stranding period spanned mid-September to mid-October. We considered how attraction to anthropogenic light influenced the geographic and temporal patterns of the strandings. We also examined the use of social media information to gauge ecological events that occur over large geographic scales. We suggest further research and conservation strategies.
Historic Bacon's Swamp in Indianapolis is commonly regarded as the southernmost Sphagnum-dominated peatland in Indiana. Although pollen analyses have been published, no previous macrofossil investigations have been conducted. Recent attempts to retrieve a sediment core to recover macrofossils and study the palaeoecology of historic Bacon's Swamp failed due to the presence of extensive and deep gravel fill overlaying the remaining wetland sediments. Discovery of core samples collected for pollen analysis in 1936, before extensive dredging and filling of the peatland, provided an unusual opportunity to recover macrofossils. Macrofossils were remarkably well-preserved, despite having been dried for nearly 85 years. Those identified in this study indicate that the ecological succession of Bacon's Swamp was markedly different than previously reported. Changes in local or regional hydrology are evident and may have controlled the onset of developmental stages. Contrary to a previous published account, Sphagnum appears to have been a relatively recent pioneer in Bacon's Swamp rather than a long-term component of the flora.
We sampled the inshore fish communities of New Bedford and Gloucester harbors synoptically using identical gear for 12 months during 1998–1999. Although the 2 harbors are only 110 km apart, they are separated by Cape Cod, which is the transition between the southern New England (New Bedford) and the Gulf of Maine (Gloucester) biogeographic regions. The 2 fish communities were 69% dissimilar from each other using the Bray–Curtis dissimilarity index (B–C). Stenotomus chrysops (Scup) composed 80% of the catch in New Bedford Harbor, did not occur in Gloucester Harbor, and contributed 7.40% to the total dissimilarity between the harbors. B–C identified 2 seasonal groups in the New Bedford Harbor fish community: May–October and November–April. Leucoraja spp. (skates) comprised the most numerous taxon captured in Gloucester Harbor, accounting for 24.90% of the total catch followed by Pseudopleuronectes americanus (Winter Flounder; 24.16%), and Gadus morhua (Atlantic Cod; 22.52%). These taxa contributed 7.23%, 3.88%, and 6.16% respectively to the total dissimilarity between harbors. B–C identified 4 seasonal groups in Gloucester Harbor: January, February and March, April and May, and June–December. These data provide an important description of the fish communities in the 2 harbors in different biogeographic regions at the end of the 20th century. We expect differences between the communities to decrease with increasing water temperature due to climate change.
Ambystoma maculatum (Spotted Salamander) is a widely distributed species in the eastern United States whose aquatic breeding habitat has been well documented as being hydrologically diverse but always freshwater in chemical composition. On Mount Desert Island, ME, a population of Spotted Salamanders breed in an aggregation of pools located atop a coastal rock cliff that is subject to seawater intrusion from nearby wave action. We periodically measured salinity concentrations (in ppt) of 7 pools with the highest breeding activity from 2016 to 2021 to quantify pool salinities within and between 5 breeding seasons. Our findings confirm that this breeding habitat experiences sporadic and extreme bouts of salt intrusion from the adjacent ocean, causing salinity levels to vary markedly and unpredictably (0.1 ppt to 32.5 ppt) on a spatiotemporal scale. The presence of salamanders exhibiting apparent normal behavior in salinities greater than 12 ppt suggest an upper threshold of salt tolerance in this population that exceeds purported upper thresholds for the majority of amphibians studied to date. Future experimental work on this population holds great promise to deepen our understanding of the underlying mechanisms of salt tolerance in coastal populations of amphibians from both a physiological and evolutionary perspective.
Samuel N. Andrews, David H. Roth, Karen A. Kidd, Scott A. Pavey, Bethany Reinhart, Brian Hayden, Michael J. Dadswell, Tommi Linnansaari, R. Allen Curry
The Morone saxatilis (Striped Bass) population in Saint John River (SJR), NB, Canada, collapsed in the 1970s concurrent with dam construction, overfishing, and chemical pollution that may have impeded reproduction. To assess whether a chemical threat to Striped Bass or a health threat to fish consumers persists, we examined DDT and total mercury (THg) levels from 29 Striped Bass captured in the SJR including 16 genomically typed as SJR natives. DDT and DDD in female gonads were below detectable levels, and DDE averaged 0.08 ± 0.09 mg/kg wet weight (ww) but was considered too low to threaten reproduction. Total mercury in muscle and liver varied from 0.68 to 2.10 mg/kg and 0.35 to 3.27 mg/kg ww, respectively and exceeded Health Canada guidelines in all samples. We suggest regulators should update advisories for consumption including actively informing the public of the risk.
The limestone bluff cedar–pine forest is a rare upland natural community that is threatened by development and invasion by exotic species. Furthermore, the sensitivity of this forest-type to changes in climate and pollution exposure is unknown. We collected xylem increment cores from 4 conifer species (Thuja occidentalis [Northern White Cedar], Juniperus virginiana [Eastern Red Cedar], Pinus strobus [Eastern White Pine], and Tsuga canadensis [Eastern Hemlock]) and 4 hardwood species (Quercus rubrum [Northern Red Oak], Quercus alba [White Oak], Fagus grandifolia [American Beech], and Fraxinus americana [White Ash]) within and close to a cedar–pine forest along the eastern shore of Lake Champlain in Vermont and correlated radial tree growth to precipitation, snow, temperature, and pollution data to assess which factors influenced growth during the time period 1937–2016. We examined growth and possible environmental drivers of it for a variety of species to evaluate how unique these may be for the cedar and pine trees emblematic of the limestone-bluff community. For both conifers and hardwoods, precipitation exhibited the strongest positive correlations with growth and occurred with greater frequency compared to other climate and pollution parameters. Snow was positively associated and temperature was negatively associated with growth for all species. Despite growing over calcium-rich bedrock, and especially for the conifers, pollution seemed to limit growth in years prior to pollution reductions enacted following the 1990 Amendments to the Clean Air Act.
Neotoma magister (Allegheny Woodrat) is a threatened species in Pennsylvania and listed as Endangered in 4 of 5 bordering states. Declining food resources, genetic isolation, habitat fragmentation, disease, and increasing predator populations are considered the primary threats to Allegheny Woodrat populations. Herein, we share an observation captured on a wildlife camera of an adult woodrat displaying agonistic behavior toward a small Crotalus horridus (Timber Rattlesnake).
During a radio-tracking study of Ammospiza nelsoni (Nelson's Sparrow) in Aulac, NB, Canada, in 2022, we observed 2 unexpected cases of predation. In the first case, we found the remains of a radio-tagged Nelson's Sparrow inside a regurgitated pellet, which presumably was from an Asio flammeus (Short-eared Owl) or a Circus hudsonius (Northern Harrier). In another case, we found an adult female Nelson's Sparrow and her nestlings buried in underground tunnels, likely having been depredated by a Mustela erminea (Short-tailed Weasel), an undocumented predator for Nelson's Sparrow. These observations contribute to greater knowledge of predation of Nelson's Sparrows and demonstrate an indirect benefit of tracking studies on wildlife.
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