College of the Atlantic
Recent publications
The olfactory rosettes of elasmobranchs vary in shape and structure among species, but the functional consequences of this diversity are unresolved. Our goal was to quantify rosette morphology on dissected as well as diceCT-imaged specimens to analyze the drivers of observed trends in a phylogenetic context and compare the methodologies. We hypothesized that lamellar count and rosette shape (fineness ratio) would not scale with animal size, but other rosette size variables would scale positively. We dissected rosettes from 14 elasmobranch species and collected morphometric data (fineness ratio, lamellar count, interlamellar distance, lamellar thickness, and raphe width). A subset of rosettes (5 species) were used to analyze the effects of body size, while all 14 species were used for a phylogenetic principal component analysis (pPCA). We found that fineness ratio and lamellar counts varied significantly among species, and were positively correlated. The first two principal components of the pPCA explained 82% of the variation, with fineness ratio and lamellar count contributing most to the loadings, respectively. Diffusible iodine-based contrast-enhanced CT (diceCT) was used for in situ imaging of four species of Carcharhiniformes. There were no significant differences between rosette structure or volume when comparing values from dissected specimens to values from in situ specimens obtained using diceCT. We also quantified the volume of the excurrent channel in the olfactory capsule. These data add to our understanding of how olfactory organ shape varies among species and can be used to create 3D models for future olfactory hydrodynamic studies. This article is protected by copyright. All rights reserved.
Over the past several decades, the Gulf of Maine has experienced significant socio‐ecological change. Coastlines have become more densely populated and developed, rapid and dramatic climate change has affected coastal ocean environments, and seal populations have grown as a result of federal protections. Long‐term data sets from marine mammal stranding networks represent a valuable resource for investigating indicator species for coastal ocean health during this period of change. Using data collected from stranded harbor (Phoca vitulina), harp (Pagophilus groenlandicus), and gray (Halichoerus grypus) seals from 2002 to 2017 in Massachusetts, New Hampshire, and Maine, we tested for spatiotemporal correlations between stranding density and human population density, size of and proximity to seal haul‐outs, sea surface temperature, North Atlantic Oscillation, snowfall, and sea ice extent. We found that in the Gulf of Maine proximity to coastal human population centers and large seal haul‐outs are the greatest drivers of reported seal stranding density. Environmental factors played an important role only for harp seals, which do not breed in the study area, although recent shifts in the environmental seascape have the potential to affect all seal species in the Gulf of Maine.
Whilst climate change has been regarded as a growing concern in recent years due the disruptive and detrimental effects experienced across the globe, one of its most compelling and threatening evidence is Sea Level Rise (SLR). This phenomenon is more prominent in Small Island Developing States (SIDS) and such islands are already facing escalating associated environmental threats, causing social and economic disruptions as well as insecurities. Amongst the SIDS, the coastal areas of Mauritius are considered among the most vulnerable to SLR, where statistics showed that between the years 1987 and 2007, an annual increase of 2.1 mm in the sea level has been observed around Mauritius. Although SLR has various associated impacts, limited work has been undertaken to assess the coastal vulnerability of the impacts of SLR for Mauritius and to compute the Coastal Vulnerability Index (CVI) of the island. Taking cognizance of this limitation, the purpose of this paper is to quantify, prioritize and critically assess the vulnerability of key impacts of sea level rise on the coastal areas of Mauritius following computation of a CVI. In this process, five key research questions are answered towards calculating the CVI of the island to eventually conceptualize a framework with the aim to reduce the adverse impacts of SLR on coastal zones of Mauritius. Findings of this study aim at the advancement of resilience and increased sustainability of coastal areas to the impacts of SLR.
Spatial and spatio-temporal data are used in a wide range of fields including environmental, health and social disciplines. Several packages in the statistical software R have been recently developed as clients for various databases to meet the growing demands for easily accessible and reliable spatial data. While documentation on how to use many of these packages exist, there is an increasing need for a one stop repository for tutorials on this information. In this paper, we present rspatialdata a website that provides a collection of data sources and tutorials on downloading and visualising spatial data using R. The website includes a wide range of datasets including administrative boundaries of countries, Open Street Map data, population, temperature, vegetation, air pollution, and malaria data. The goal of the website is to equip researchers and communities with the tools to engage in spatial data analysis and visualisation so that they can address important local issues, such as estimating air pollution, quantifying disease burdens, and evaluating and monitoring the United Nation’s sustainable development goals.
Forests that regrow naturally on abandoned fields are important for restoring biodiversity and ecosystem services, but can they also preserve the distinct regional tree floras? Using the floristic composition of 1215 early successional forests (≤20 years) in 75 human-modified landscapes across the Neotropic realm, we identified 14 distinct floristic groups, with a between-group dissimilarity of 0.97. Floristic groups were associated with location, bioregions, soil pH, temperature seasonality, and water availability. Hence, there is large continental-scale variation in the species composition of early successional forests, which is mainly associated with biogeographic and environmental factors but not with human disturbance indicators. This floristic distinctiveness is partially driven by regionally restricted species belonging to widespread genera. Early secondary forests contribute therefore to restoring and conserving the distinctiveness of bioregions across the Neotropical realm, and forest restoration initiatives should use local species to assure that these distinct floras are maintained.
The construction of hypothetical environments to produce organic molecules such as metabolic intermediates or amino acids is the subject of ongoing research into the emergence of life. Experiments specifically focused on an anabolic approach typically rely on a mineral catalyst to facilitate the supply of organics that may have produced prebiotic building blocks for life. Alternatively to a true catalytic system, a mineral could be sacrificially oxidized in the production of organics, necessitating the emergent ‘life’ to turn to virgin materials for each iteration of metabolic processes. The aim of this perspective is to view the current ‘metabolism-first’ literature through the lens of materials chemistry to evaluate the need for higher catalytic activity and materials analyses. While many elegant studies have detailed the production of chemical building blocks under geologically plausible and biologically relevant conditions, none appear to do so with sub-stoichiometric amounts of metals or minerals. Moving toward sub-stoichiometric metals with rigorous materials analyses could finally demonstrate the viability of an elusive cornerstone of the ‘metabolism-first’ hypotheses: catalysis. We emphasize that future work should aim to demonstrate decreased catalyst loading, increased productivity, and/or rigorous materials analyses for evidence of true catalysis.
Historic North American apple (Malus domestica) orchards that thrived in the late 19th and early 20th centuries, with cultivar compositions unlike today's orchards, are vanishing. There are several reasons for this loss: tree aging, cost of tree maintenance, and urbanization. Many groups have collected local knowledge regarding the history and horticulture of apples using both phenotypic and genotypic identification methods. Some of these groups have joined with scientists to form the collaborative “Historic Fruit Tree Working Group of North America” to facilitate the conservation of heirloom apple cultivars in North America through documentation, identification, collaboration, and education. Historic North American apple (Malus domestica) orchards that thrived in the late 19th and early 20th centuries, with cultivar compositions unlike today's orchards, are vanishing. There are several reasons for this loss: tree aging, cost of tree maintenance, and urbanization. Many groups have collected local knowledge regarding the history and horticulture of apples using both phenotypic and genotypic identification methods. Some of these groups have joined with scientists to form the collaborative “Historic Fruit Tree Working Group of North America” to facilitate the conservation of heirloom apple cultivars in North America through documentation, identification, collaboration, and education.
Due to the outbreak of Covid-19 pandemic, activities in most sectors- be it business, education or even healthcare- are taking place in an online rather than in an inline style, and as a result, Internet traffic has increased drastically. Recent studies have highlighted that internet traffic has grown by 70% to 300% since March 2020. According to a recent CNN news article (https://www.cnn.com/2020/03/19/tech/netflix-internet-overload-eu/index.html), popular content providers such as Netflix and YouTube are slowing down in North-America and Europe to keep the internet from breaking. With that being addressed, the existing network deployment and solutions, even with the fifth generation mobile communication (5G) partial deployment, are currently under a huge burden. This work intends to review the integration of two of the most innovative network research areas, Software-defined Networks (SDN) and the Internet of Things (IoT). The IoT aims to interface questions over the Internet while the SDN offers orchestration for network management by decoupling the control plane and the data plane. In this article, we present the state of the art of Software-defined networking and the Internet of Things discussing the integrated architectures, challenges, and designs. Also, we discuss two proposals targeting the QoS Key Performance Indicators (KPIs) in IoT via SDN mobile edge computing along with a few directions of possible research that could fill in gaps in these domains.
Tetracyclines (TCs) have been extensively used for humans and animal diseases treatment and livestock growth promotion. The consumption of such antibiotics has been ever-growing nowadays due to various bacterial infections and other pathologic conditions, resulting in more discharge into the aquatic environments. This brings threats to ecosystems and human bodies. Up to now, several attempts have been made to reduce TC amounts in the wastewater, among which photocatalysis, an advanced oxidation process, is known as an eco-friendly and efficient technology. In this regard, metal organic frameworks (MOFs) have been known as the promising materials as photocatalysts. Thus, studying TC photocatalytic degradation by MOFs would help scientists and engineers optimize the process in terms of effective parameters. Nevertheless, the costly and time-consuming experimental methods, having instrumental errors, encouraged the authors to use the computational method for a more comprehensive assessment. In doing so, a wide-ranging databank including 374 experimental data points was gathered from the literature. A powerful machine learning method of Gaussian process regression (GPR) model with four kernel functions was proposed to estimate the TC degradation in terms of MOFs features (surface area and pore volume) and operational parameters (illumination time, catalyst dosage, TC concentration, pH). The GPR models performed quite well, among which GPR-Matern model shows the most accurate performance with R2, MRE, MSE, RMSE, and STD of 0.981, 12.29, 18.03, 4.25, and 3.33, respectively. In addition, an analysis of sensitivity was carried out to assess the effect of the inputs on the TC photodegradation by MOFs. It revealed that the illumination time and the surface area play a significant role in the decomposition activity.
In this paper we examine definitions of ‘greenwashing’ and its different forms, developing a tool for assessing diverse ‘green’ claims made by various actors. Research shows that significant deception and misleading claims exist both in the regulated commercial sphere, as well as in the unregulated non-commercial sphere (e.g., governments, NGO partnerships, international pledges, etc.). Recently, serious concerns have been raised over rampant greenwashing, in particular with regard to rapidly emerging net zero commitments. The proposed framework we developed is the first actionable tool for analysing the quality and truthfulness of such claims. The framework has widespread and unique potential for highlighting efforts that seek to delay or distract real solutions that are urgently needed today to tackle multiple climate and environmental crises. In addition, we note how the framework may also assist in the development of practices and communication strategies that ultimately avoid greenwashing.
Active faults in the forearc of southern Peru pose a poorly understood hazard to the region. The Purgatorio Fault is a 60 km-long fault that extends between Moquegua and Tacna that has hosted several scarp-forming earthquakes over the last 6 ka. We present new measurements of the fault scarp geomorphology along the Purgatorio Fault, and use dating of the stratigraphy within a new paleoseismic trench excavated across the fault to establish the chronology of scarp formation. We find that the most recent surface-rupturing earthquake on the Purgatorio Fault occurred sometime between 1630C.E and 1790C.E and had a moment magnitude (Mw) of ~7. We propose that this most recent surface-rupturing earthquake on the Purgatorio Fault was the 1715C.E earthquake recorded in the historical catalogue of the region, which was previously attributed to the megathrust offshore. Our results highlight the importance of establishing a paleoseismic record of onshore faults to differentiate between major megathrust and forearc earthquakes. Given the proximity of these shallow, onshore faults to coastal communities in Peru, the shallow earthquakes they generate may pose a severe, yet often overlooked, seismic hazard.
Tropical secondary forests play an increasing role in biodiversity conservation and climate change mitigation, but the underlying mechanisms driving the successional trajectory to old-growth forests are still not fully characterized. Species with different dispersal abilities or habitat preferences affect the compositional similarity of secondary forests to old-growth forests. We studied the dynamics of forest succession in twelve 1-ha plots of tropical secondary forests on Hainan Island, China, using ten years of census data (2010–2020). We compared the variations in demographic rates and community composition among three successional stages, with four plots each in young secondary forest (YS), old secondary forest (OS), and old-growth forest (OG). The effects of five species groups (generalists, rare species, and specialists in each of the three successional stages) on successional trajectory were explored using sensitivity analysis. Species richness in the OS only reached 65% of OG after 60 years of succession. The diameter growth, mortality, and recruitment rates were the highest in the YS and the lowest at the OG. Growth decreased and recruitment increased during the second census period (2015–2020) during which there were two extended droughts, but there was no significant change in mortality rate. The successional trajectories of YS and OS showed a slow but directional trend towards the OG, with a weak stochastic component. The five species groups made different contributions to the successional trajectory. Generalists contributed to the convergence of secondary forests to old-growth forests, while old-growth specialists contributed to divergence. Secondary species usually contributed to divergence with old-growth forest, and young-secondary specialists had a stronger effect than old-secondary specialists. The divergence effect of rare species on similarity occurred only when presence data were used. When based on abundance data, rare species had little effect on community similarity. Overall, our results indicated that the successional trajectories of our tropical secondary forests moved towards OG but the recovery rate was slow. Both deterministic and stochastic processes contribute to secondary succession, but deterministic processes dominated. Furthermore, it is necessary to emphasize the different contributions of species with different habitat specialization to the successional trajectory, in order to better predict successional outcomes and prioritize conservation targets.
A culinary exploration of the role of CO2 in leavening is described. This demonstration substitutes dry ice for chemical leaveners in order to achieve the same pancake fluffiness. Under the universal framework of food and cooking, we developed this activity to bring aspects of phase transitions and chemical transformations to a broad audience.
Body temperature influences the activity and behavior of reptiles, with warmer body temperatures typically being associated with improved performance. Nocturnal ambush-hunting rattlesnakes would therefore benefit from selecting warmer substrate hunting sites, allowing them to stay in ambush longer as the environment cools and, presumably, to have a higher probability of striking prey successfully. Here, we tested whether free-ranging sidewinder rattlesnakes (Crotalus cerastes) might select ambush sites based on substrate temperature. We used a thermal imaging camera to measure snake body temperature and substrate temperature at ambush sites and random locations. Rattlesnake body temperature showed a strong positive correlation with substrate temperature at the ambush site, and the substrate at ambush sites was significantly warmer than randomly chosen sites. This suggests snakes might select ambush sites based on substrate temperature. Desert pit vipers appear highly attuned to environmental conditions and might integrate several criteria to select microhabitats that increase predation success.
To meet UN Sustainable Development goals, a clean-energy transition with minimal ecological impact from its raw-material supply chain is essential. Polymetallic nodules lying unattached on the abyssal seafloor of the Pacific Ocean's Clarion Clipperton Zone contain four critical metals (nickel, cobalt, manganese, copper) in large quantities, and the International Seabed Authority may soon enact regulations to allow their commercial exploitation. There are complex global ecological implications of doing so. Nodule exploitation would damage abyssal habitats and may impact midwater-column organisms; but in the absence of nodule exploitation, terrestrial mining's environmental and social impacts would intensify. This paper adds to the growing systems-based literature on nodule collection by contributing a preliminary material flow analysis of global-average cradle-to-gate waste streams using either nodules or terrestrial sources as part of a preliminary life cycle assessment, as well as integrated risk assessments of those waste streams. System endpoints are battery precursors (nickel sulfate, cobalt sulfate, manganese sulfate), copper cathode, and a 40% or 75% manganese product. Overburden, tailings, and processing and refining wastes from terrestrial mining are compared to the nodule industry's anticipated offshore and onshore wastes, including sediment disrupted by nodule-collection machines. Robustness to offshore technology assumptions is tested using Monte Carlo simulation, while onshore mass-flow scenarios incorporate a “negligible-waste” flowsheet and high-waste flowsheets where manganese is not recovered. A billion-EV scenario incorporates the effects of declining terrestrial copper and nickel ore grades. Results imply that metal production from nodules may produce less waste of lower severities, caveated by uncertain impacts of disrupted sediment.
Baleen whales are subject to a myriad of natural and anthropogenic stressors, but understanding how these stressors affect physiology is difficult. Measurement of adrenal glucocorticoid (GC) hormones involved in the vertebrate stress response (cortisol and corticosterone) in baleen could help fill this data gap. Baleen analysis is a powerful tool, allowing for a retrospective re-creation of multiple years of GC hormone concentrations at approximately a monthly resolution. We hypothesized that whales that died from acute causes (e.g. ship strike) would have lower levels of baleen GCs than whales that died from extended illness or injury (e.g. long-term entanglement in fishing gear). To test this hypothesis, we extracted hormones from baleen plates of four humpback whales (Megaptera novaeangliae) with well-documented deaths including multiple and chronic entanglements (n = 1, female), ship strike (n = 2, male and female) and chronic illness with nutritional stress (n = 1, male). Over ~3 years of baleen growth and during multiple entanglements, the entangled whale had average corticosterone levels of 80–187% higher than the other three whales but cortisol levels were similar to two of the other three whales. The nutritionally stressed and chronically ill whale showed a slow increase in both cortisol and corticosterone spanning ~3 years, followed by a sharp decline in both hormones before death, possibly indicative of adrenal failure in this moribund individual. This whale’s correlation between cortisol and corticosterone was significant but there were no correlations in the other three whales. Our results show that cortisol and corticosterone concentrations vary according to the type and duration of illness or injury. Single-point GC concentrations should be interpreted with caution as low values can occur in whales experiencing pronounced stress and individual baselines can be highly variable. Baleen analysis is a promising tissue type for retrospective analyses of physiological responses to various stressors affecting baleen whales.
Naylor et al . argue that the existence of multiple denticle types within a single species precludes the use of this metric as a measure of the decline of multiple shark species. We show that species-level shark diversity would have to decrease by >90% to account for the observed >70% denticle extinction, implying that the early Miocene shark extinction was larger than previously recognized.
Feichtinger et al . assert that the reduction in denticle abundance and diversity we found are incorrect, claiming that we failed to consider changes in sedimentation rate. However, we used standard methods that explicitly account for changes in sedimentation rate and density. We maintain that our initial dataset and conclusions are robust and provide evidence for a major early Miocene extinction in pelagic sharks.
Resilient secondary tropical forests? Although deforestation is rampant across the tropics, forest has a strong capacity to regrow on abandoned lands. These “secondary” forests may increasingly play important roles in biodiversity conservation, climate change mitigation, and landscape restoration. Poorter et al . analyzed the patterns of recovery in forest attributes (related to soil, plant functioning, structure, and diversity) in 77 secondary forest sites in the Americas and West Africa. They found that different attributes recovered at different rates, with soil recovering in less than a decade and species diversity and biomass recovering in little more than a century. The authors discuss how these findings can be applied in efforts to promote forest restoration. —AMS
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287 members
Sarah R Hall
  • Environmental Science
Daniel Dendanto
  • Allied Whale
Peter Stevick
  • Allied Whale
C. W. Petersen
  • Department of Biology
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