2199 research outputs found
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Epidemiology of Staphylococci collected from Boston-area wild rodents
No full textAs Staphylococcus aureus strains evolve and gain resistance to antibiotics, the risk of bidirectional transmission of resistant strains between humans and animals increases. The objective of this study was to identify and type S. aureus among wild rodents in Boston, Massachusetts, to examine their genetic relationship to common human and animal isolates. A total of 168 bacterial isolates collected from 45 Brown rats (Rattus norvegicus) in Boston proper were analyzed. Polymerase chain reaction was used to detect the mecA and PVL genes. All S. aureus isolates were spa typed. A subset of isolates was characterized via multi-locus sequence typing (MLST). All S. aureus isolates were tested for antibiotic susceptibility. Overall prevalence of S. aureus was 11.9% (20/168). Of all S. aureus, 5.0% (1/20) were MRSA (based on detection of the mecA gene which encodes methicillin-resistance) and 95.0% (19/20) were methicillin-susceptible S. aureus (MSSA). All isolates tested resistant to benzylpenicillin. Two isolates were resistant to erythromycin and one isolate was resistant to four antibiotics, including oxacillin. Of the 20 isolates, 75.0% (15/20) were spa type t933. MLST results to date show that these are sequence type (ST) 1094. Additional molecular testing is ongoing. Our results indicate that wild rats from Boston, MA are carriers of S. aureus. Additional study is needed to examine the distribution of t933/ST1094, an uncommon strain previously found in ewes in Tunisia. Further research is warranted to identify and characterize lineages of S. aureus strains in order to minimize the risk of Staphylococcal infection from city rodents. </p
Holocene changes in algal abundance and dissolved oxygen discovered in Sluice Pond, MA through spectroscopy and analysis of a sediment core
No full textThroughout the Holocene, Sluice Pond (Lynn, MA, USA), has experienced fluctuations in algal communities and dissolved oxygen (DO) content based on measurements from a sediment core raised from its anoxic central basin. The variability in the core’s composition can be mapped with Visible Derivative Spectroscopy based on varimax-rotated, principal component analysis (VPCA) through wavelet analysis and by plotting this information against an AMS 14C constrained age model. The temporal history yields a better understanding of the lake’s changing environment and provides insight into the extent of preserved natural and human events. Thirteen separate constituents were present in the core, as mixtures of six different orthogonal (or independent) VPCA components that account for 97.1% of the variance in the data set. Six components were extracted overall, but a detailed look at two is presented in this project. Through the data collected in 6VPCA1 and in 6VPCA6, algal blooms and lake turbidity can be mapped out and referenced against the age model to show changes in relative concentration. The data shows anoxic conditions through the increase or decrease of DO indicators. The first component oscillates on a period of 4 ka, and the second has a 6 ka oscillation. Major climate events such as the Younger Dryas and the 8.2-kiloyear event are represented in the data by a large drop in algal concentrations and an increase in DO during both extreme cold events. Within the last 200 years, fluctuations in algal blooms, turbidity, and DO have increased dramatically in both frequency and extent. Through the data and methods used in this project, we are given a representation of the natural variance over the Holocene and can start to understand how humans may have impacted Sluice Pond. This new information allows for a better understanding of the conditions Sluice Pond has experienced in the past and can inform us on steps that need to be taken for the overall health of the lake.
Fostering a people\u27s forest: using Citizen Science-driven biodiversity monitoring to understand restoration processes
No full textEcosystem restoration takes place over a longer time scale than the typical ecological study, particularly when the ecosystem includes slow-growing taxa, such as trees. Yet, humans take strong interest in ecosystem restoration- both as a process to participate in (i.e. contributing to tree planting and Citizen Science), and as a process to measure (i.e. asking “is our restoration activity working?”). This project examines both of these facets through restoration activities within former surface mine sites at Cuyahoga Valley National Park. We use the lens of beetle communities observed through participatory models of data collection to examine how functional groups of organisms can give information on how an ecosystem is operating. With the help of community members, we will conduct “bio-blitzes” and systematic sampling to document Coleoptera communities within 5 sites undergoing restoration, and their surrounding forest at CVNP. We will then use these communities to describe the functional ‘health’ of their surrounding landscape. This project will also examine how effectively citizen scientists contribute to ecological research within a national park and what implications this may have on future ecological research. We will combine these data with observations from public databases (iNaturalist) and use these data to effectively map the ‘health’ of mature and restored forest within CVNP– with respect to beetle community composition - providing a means to assess the effectiveness of Citizen Science on supporting ecological research
Food Web Structure in a Constructed Wetland
No full textWetlands are globally important ecosystems known for strong interactions among aquatic and terrestrial animals and plants. While natural wetlands are known for their complex food webs, constructed wetlands are often simpler, containing reduced levels of biodiversity. However, these systems generally reflect similar inter- and intra-specific interactions, with the advantage of having replicate sites. This project assessed food web interactions of macrofauna in ten wetland cells during an 8-week summer period in constructed wetlands at Kent State University. In each wetland cell, fish and amphibian (tadpoles/adults) assemblages were sampled twice/week using modified minnow traps to gain insight into population size and fish/amphibian size distributions. Next, to assess mammal and bird activity and their potential interactions in these wetlands, game cameras were strategically placed around each of the wetlands. Finally, odonates (i.e., dragonflies and damselflies) were also identified and counted in each wetland. Overall, species richness was relatively low, with only two fish species and two frog species captured from the minnow traps. In contrast, multiple mammal, bird, and odonate species were detected at the site in other sampling. Analyses of food web structure suggest a strong, negative relationship between sunfish abundance and frog/tadpole abundance and level of development, likely as a result of predation. The distribution of beavers, green herons, and great blue herons also appeared to be associated with food availability (woody vegetation for beavers, fish/frogs for herons). In summary, while simple, the food web in these constructed wetlands was structured similarly to what we see in natural wetlands
Predicting Lake Erie Algal Blooms based on Alternate Ecosystem States Theory: Early Warning Signals of an Impending Bloom
No full textAlgal blooms have become a yearly occurrence in Lake Erie for some time now. These blooms are not only a nuisance but can also pose a risk to human health. Theoretically, early warning signals will exist prior to a shift in ecosystem state, i.e. an algal bloom. Indicators, such as increasing variance and rising autocorrelation close to 1, have been associated with transitions to alternate ecosystem states. These early warning signals have been observed in some whole-ecosystem experiments using quickest detection (QD) methods. The goal of this study was to determine if these early warning signals were detected in chlorophyll data prior to an algal bloom in a real-life ecosystem, Lake Erie. The QD method for detecting early warning signals associated with shifts in ecosystem states was used. In Lake Erie, the shift from a mixed phytoplankton state to a cyanobacterial dominated state was considered a transition to an alternate ecosystem state. Results showed that increasing variance before an algal bloom was not always detected, and therefore early warning signals of an impending algal bloom were not seen. The research suggests that examining phycocyanin, a pigment specific to blue-green algae, may provide more promising results in the future. If successful, this research could be used to provide warnings of impeding algal blooms to water treatment managers, allowing them to be prepared for the situation
Bacterial colonization on different microplastics in a local stream in Northeast Ohio
No full textResearch was performed to understand bacterial colonization on different types of microplastics in a local stream in Northeast Ohio. Disks were placed in bags constructed mesh fabric with 1000 µm diameter. Sampling was done at various intervals to determine early and late colonizers within bacterial communities on microplastics in freshwater. Microplastics (diameters <5mm) are a global concern in environmental sciences and are readily colonized by bacteria in the environment. The term "plastisphere" has been used to describe bacterial communities residing on microplastics. The composition of the communities inside the plastisphere has been affected by the physicochemical properties of different microplastic types. Plastics have variations in physicochemical properties based on their intended applications. For example, polyethylene (PE) has a net negative charge while polypropylene (PP) has a net neutral charge at the pH of seawater. Subsequently, DNA was extracted from microbes adhering to disks and the plastisphere community composition will be determined from the V6 hypervariable region of 16S rDNA using 16S MiSeq 250 sequencing. Sampled disks will also be analyzed for differences in surface roughness, buoyancy, and weight after bacterial colonization. As the study progressed, microplastic disks broke down and had increased surface roughness
Comparing Stream Nitrate Concentrations in Baseflow and Stormflow Conditions across Urban Watersheds
No full textDegraded water quality is common in urban streams due to increased impervious surface cover, which can input stormwater runoff directly into the stream. Nitrate, which enters streams from sewage inputs or runoff from fertilizer and atmospheric deposition, is a common contaminant in urban watersheds. Nitrate concentrations can vary throughout a stream network due to land cover and urban infrastructure influences including proximity to sewer lines and stream burial. Three urban watersheds (5-15 km2) in Summit County, Ohio with similar impervious surface cover, but spatially variable land cover metrics to understand urbanization on nitrate concentrations. Biweekly sampling of 26 sites between October 2017 and October 2018 was accompanied by 5-minute conductivity and water level data, as well as storm event sampling in August and September 2018. Baseflow concentrations showed that nitrate has higher concentrations and more variation between sampling locations in the summer (2-9 mg/L), with little variation in the winter (/L). During storm events, nitrate concentrations changed in response to water level, with generally lower concentrations at high water level due to dilution. Nitrate concentrations varied at baseflow and stormflow between watersheds, possibly due to differences in land cover metrics. Understanding water quality response to discharge provides greater insight into the mechanisms affecting urban water quality, allowing managers to better predict impairment and target land use and stormwater actions that will improve water quality
Short-term sea-level fluctuations along the eastern seaboard of the US and their atmospheric connections
No full textIn this research, we assess the impact of short-term events, combined with sea-level rise, through synoptic climatological analysis, exploring whether circulation pattern identification can be used to enhance probabilistic forecasts of flood likelihood. Self-organizing maps (SOMs) were created for two discrete atmospheric variables: 700-hPa geopotential height (700z) and sea-level pressure (SLP). For each variable, a SOM array of patterns was created based on data spanning 25°-50°N and 60°-90°W for the period 1979-2014. Sea-level values were derived from tidal gauges between Cape May, New Jersey and Charleston, South Carolina, along the mid-Atlantic coast of the US. Both anomalous sea-level values, as well as nuisance flood occurrence (defined using the local gauge threshold), were assessed. Results show the impacts of both the inverted barometer effect as well as surface wind forcing on sea levels. With SLP, higher sea levels are associated with either patterns that were indicative of on-shore flow or cyclones. At 700z, ridges situated along the east coast are associated with higher sea levels. As the SOM matrix arranges atmospheric patterns in a continuum, the nodes of each SOM show a clear spatial pattern in terms of anomalous sea level, including some significant sea-level anomalies associated with relatively ambiguous pressure patterns. Further, multi-day transitions are also analyzed, showing rapidly deepening cyclones, or persistent onshore flow, can be associated with the greatest likelihood of nuisance floods
Analysis of Cold Air Outbreaks Across the Globe
No full textPeriods of anomalously cold temperatures impact regions of the globe every winter. Depending on the magnitude and duration of the occurrence, extremely cold periods may be deemed cold air outbreaks (CAOs), which can be detrimental to the agricultural industry and human health. A systematic CAO classification was developed from gridded NCEP/NCAR reanalysis data, from 1948 through 2017, based on a set of criteria concerning magnitude, duration, and spatial extent. Statistical analyses of the data were used to determine the overall trends in CAOs for different regions across the globe. This research will be used to further understand the large scale atmospheric mechanisms that precede these CAOs and how the specific mechanisms impact the location of CAOs
Temporal patterns and Interactions of Bacteria, Algae, and Zooplankton following a Freshwater Reservoir Cyanobacterial Bloom
No full textThe frequency and severity of cyanobacterial bloom are at risk of increasing as a consequence of eutrophication and increased water temperature. The elevated cyanobacterial biovolume can have substantial impacts on water ecosystem function by producing toxic secondary metabolites and subsequent induction of hypoxia affecting microbial community structure and biogeochemical cycles. Here we combined 16S rRNA gene sequencing and microscopic cell counting to explore the seasonality and co-occurrence patterns of bacteria, algae, and zooplankton following a reservoir cyanobacterial bloom. During the sampling period, 22 distinct cyanobacteria genus were identified, and the dominant ones were Chroococcus, Planktolyngbya, Aphanizomenon, Pseudanabaena, and Cylindrospermopsis. Our results showed that the bloom event significantly altered the bacterial community composition without affecting the alpha diversity. Time-lag analysis found that the similarities of microbial communities significantly declined with the increase in time-lag. Regression modeling showed that environmental variables strongly affect the distribution of functional profiles, but weakly influence taxonomic composition within individual functional groups. Neutral community modeling revealed that stochastic processes also strongly affected bacterial community assembly, and the fit of the model varied over the sampling period and was the lowest during the bloom. Co-occurrence network analysis showed that correlations between bacterial taxa were predominantly positive, suggesting cooperation interactions might contribute to the stability of the microbial community during cyanobacterial succession. Overall, we concluded that changes in the structure of bacterioplankton are associated with the changes in the abundance and composition of freshwater cyanobacteria