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Biology Faculty Publications

Connecticut College

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Full-Text Articles in Life Sciences

Nonconsumptive Effects Of Crustaceans And An Echinoderm On Spat Of The Eastern Oyster Crassostrea Virginica (Gmelin, 1791), Maria Rosa, Mike Gilman, Sarah Anderson, Adrian Beckford, Ben Gilfond, Nicole Wright, David M. Hudson Jan 2023

Nonconsumptive Effects Of Crustaceans And An Echinoderm On Spat Of The Eastern Oyster Crassostrea Virginica (Gmelin, 1791), Maria Rosa, Mike Gilman, Sarah Anderson, Adrian Beckford, Ben Gilfond, Nicole Wright, David M. Hudson

Biology Faculty Publications

Predation by crustaceans and echinoderms is a significant driver of mortality for sessile invertebrates in near-shore marine ecosystems. As a response, shellfish growers use predator exclusion cages to grow their product. Oysters grown in these cages and clams in and under nets have been observed to exhibit thinner, brittle shells, which is not optimal for market, nor for those being grown for restoration purposes. Here, the nonconsumptive predator effects of several native and nonnative predators on shell morphology of Crassostrea virginica oyster spat. Juvenile (1–3 mm) seed oysters were exposed separately to chemical cues of five different predators and one …


Determinants Of Food Selection By Bivalve Larvae, Maria Rosa, Diane K. Padilla Mar 2022

Determinants Of Food Selection By Bivalve Larvae, Maria Rosa, Diane K. Padilla

Biology Faculty Publications

Selection of food particles for consumption by larvae impacts nutritional gain needed for growth, development, and metamorphosis. Past work has suggested that molluscan larvae are capable of collecting food within a narrow size range. Recent studies have found evidence of size-independent food selection in molluscan larvae, but relatively little is known about the characteristics of particles that larvae preferentially capture. Therefore, we conducted experiments with the larvae of two mussels, Mytilus trossulus and Mytilus edulis, to determine whether they are selective feeders, and if so, whether we could determine the characteristics of particles selected as food. We fed larvae microalgae …


Resistance And Resilience Of Virgin Islands Bird Populations Following Severe Hurricanes, Robert A. Askins, David N. Ewert Jan 2020

Resistance And Resilience Of Virgin Islands Bird Populations Following Severe Hurricanes, Robert A. Askins, David N. Ewert

Biology Faculty Publications

We analyzed changes in abundance of terrestrial birds on St. John, U.S. Virgin Islands, for a 32 year period during which 3 major hurricanes occurred. Using 1987 as a baseline year, because it followed a 27 year hiatus when no major hurricanes hit the island, we assessed the impact of hurricanes on vegetation structure and bird populations. Bird abundance was determined for 25 m radius circular plots that were surveyed each year of the study along the same transects. Percent cover of trees, shrubs, and herbs was measured in each plot in 1987, 1990, and 2019. All of the survey …


Factors Affecting Gastropod Larval Development And Performance: A Systematic Review, Maria Rosa, Dianna K. Padilla, David Charifson, Alyssa Liguori, Mica Mccarty-Glenn, Allison Rugila Oct 2018

Factors Affecting Gastropod Larval Development And Performance: A Systematic Review, Maria Rosa, Dianna K. Padilla, David Charifson, Alyssa Liguori, Mica Mccarty-Glenn, Allison Rugila

Biology Faculty Publications

The goal of this article was to use a systematic review of studies on the larval stages of gastropods reared to metamorphosis to determine whether there are general patterns for the effects of temperature, rearing density, and food availability on larval development and performance among species, major taxa, and modes of development. Most studies did not include sufficient metadata to be included in many of the analyses. For all analyses, there were differences among major groups of taxa in terms of response to the considered variables. Increased temperature was frequently correlated with decreased development time and increased growth but often …


Population Dynamics And Community Composition Of Ammonia Oxidizers In Salt Marshes After The Deepwater Horizon Oil Spill, Anne E. Bernhard, Roberta Sheffer, Anne E. Giblin, John M. Marton, Brian J. Roberts Jun 2016

Population Dynamics And Community Composition Of Ammonia Oxidizers In Salt Marshes After The Deepwater Horizon Oil Spill, Anne E. Bernhard, Roberta Sheffer, Anne E. Giblin, John M. Marton, Brian J. Roberts

Biology Faculty Publications

The recent oil spill in the Gulf of Mexico had significant effects on microbial communities in the Gulf, but impacts on nitrifying communities in adjacent salt marshes have not been investigated. We studied persistent effects of oil on ammonia-oxidizing archaeal (AOA) and bacterial (AOB) communities and their relationship to nitrification rates and soil properties in Louisiana marshes impacted by the Deepwater Horizon oil spill. Soils were collected at oiled and unoiled sites from Louisiana coastal marshes in July 2012, 2 years after the spill, and analyzed for community differences based on ammonia monooxygenase genes (amoA). Terminal Restriction Fragment …


Rabbits And Rebounding Populations Bring Hope For Shrubland Birds, Robert A. Askins, Christopher R. Field Jan 2016

Rabbits And Rebounding Populations Bring Hope For Shrubland Birds, Robert A. Askins, Christopher R. Field

Biology Faculty Publications

No abstract provided.


Response Of Bird Populations To Long-Term Changes In Local Vegetation And Regional Forest Cover, Mary Buchanan, Robert A. Askins, Chad C. Jones Jan 2016

Response Of Bird Populations To Long-Term Changes In Local Vegetation And Regional Forest Cover, Mary Buchanan, Robert A. Askins, Chad C. Jones

Biology Faculty Publications

We analyzed data from a woodland site for a 59-year period to determine whether changes in bird populations are related to changes in the diversity and relative abundance of woody plant species even when vegetation structure, degree of forest fragmentation in the surrounding landscape, and regional changes in bird populations are taken into account. Principal component analyses generated vegetation factors encompassing variables such as total basal area, shrub density, basal area of common tree species, and measures of tree and shrub species diversity. We also calculated a forest edge/ forest area index based on GIS analysis of the landscape within …


Long-Term Impacts Of Disturbance On Nitrogen-Cycling Bacteria In A New England Salt Marsh, Anne E. Bernhard, Courtney Dwyer, Adrian Idrizi, Geoffrey Bender, Rachel Zwick Feb 2015

Long-Term Impacts Of Disturbance On Nitrogen-Cycling Bacteria In A New England Salt Marsh, Anne E. Bernhard, Courtney Dwyer, Adrian Idrizi, Geoffrey Bender, Rachel Zwick

Biology Faculty Publications

Recent studies on the impacts of disturbance on microbial communities indicate communities show differential responses to disturbance, yet our understanding of how different microbial communities may respond to and recover from disturbance is still rudimentary. We investigated impacts of tidal restriction followed by tidal restoration on abundance and diversity of denitrifying bacteria, ammonia-oxidizing bacteria (AOB), and ammonia-oxidizing archaea (AOA) in New England salt marshes by analyzing nirS and bacterial and archaeal amoA genes, respectively. TRFLP analysis of nirS and betaproteobacterial amoA genes revealed significant differences between restored and undisturbed marshes, with the greatest differences detected in …


The Critical Importance Of Large Expanses Of Continuous Forest For Bird Conservation, Robert A. Askins Jan 2015

The Critical Importance Of Large Expanses Of Continuous Forest For Bird Conservation, Robert A. Askins

Biology Faculty Publications

No abstract provided.


Differential Responses Of Ammonia-Oxidizing Archaea And Bacteria To Long-Term Fertilization In A New England Salt Marsh., Xuefeng Peng, Erik Yando, Erica Hiildebrand, Courtney Dwyer, Anne Kearney, Alex Waciega, Ivan Valiela, Anne E. Bernhard Jan 2013

Differential Responses Of Ammonia-Oxidizing Archaea And Bacteria To Long-Term Fertilization In A New England Salt Marsh., Xuefeng Peng, Erik Yando, Erica Hiildebrand, Courtney Dwyer, Anne Kearney, Alex Waciega, Ivan Valiela, Anne E. Bernhard

Biology Faculty Publications

Since the discovery of ammonia-oxidizing archaea (AOA), new questions have arisen about population and community dynamics and potential interactions between AOA and ammonia-oxidizing bacteria (AOB). We investigated the effects of long-term fertilization on AOA and AOB in the Great Sippewissett Marsh, Falmouth, MA, USA to address some of these questions. Sediment samples were collected from low and high marsh habitats in July 2009 from replicate plots that received low (LF), high (HF), and extra high (XF) levels of a mixed NPK fertilizer biweekly during the growing season since 1974. Additional untreated plots were included as controls (C). Terminal restriction fragment …


Positive Relationships Between Association Strength And Phenotypic Similarity Characterize The Assembly Of Mixed-Species Bird Flocks Worldwide, Hari Sridhar, Umesh Srinivasan, Robert A. Askins, Julio Cesar Canales-Delgadillo, Chao-Chieh Chen, David N. Ewert, George A. Gale, Eben Goodale, Wendy K. Gram, Patrick J. Hart, Keith A. Hobson, Richard L. Hutto, Sarath W. Kotagama, Jessie L. Knowlton, Tien Ming Lee, Charles A. Munn, Somchai Nimnuan, B. Z. Nizam, Guillaume Péron, V. V. Robin, Amanda D. Rodewald, Paul G. Rodewald, Robert L. Thomson, Pranav Trivedi, Steven L. Van Wilgenburg, Kartik Shanker Dec 2012

Positive Relationships Between Association Strength And Phenotypic Similarity Characterize The Assembly Of Mixed-Species Bird Flocks Worldwide, Hari Sridhar, Umesh Srinivasan, Robert A. Askins, Julio Cesar Canales-Delgadillo, Chao-Chieh Chen, David N. Ewert, George A. Gale, Eben Goodale, Wendy K. Gram, Patrick J. Hart, Keith A. Hobson, Richard L. Hutto, Sarath W. Kotagama, Jessie L. Knowlton, Tien Ming Lee, Charles A. Munn, Somchai Nimnuan, B. Z. Nizam, Guillaume Péron, V. V. Robin, Amanda D. Rodewald, Paul G. Rodewald, Robert L. Thomson, Pranav Trivedi, Steven L. Van Wilgenburg, Kartik Shanker

Biology Faculty Publications

Competition theory predicts that local communities should consist of species that are more dissimilar than expected by chance. We find a strikingly different pattern in a multicontinent data set (55 presence-absence matrices from 24 locations) on the composition of mixed-species bird flocks, which are important sub-units of local bird communities the world over. By using null models and randomization tests followed by meta-analysis, we find the association strengths of species in flocks to be strongly related to similarity in body size and foraging behavior and higher for congeneric compared with noncongeneric species pairs. Given the local spatial scales of our …


Effects Of Vegetation, Corridor Width And Regional Land Use On Early Successional Birds On Powerline Corridors, Robert A. Askins, Corrine M. Folsom-O'Keefe, Margaret C. Hardy Feb 2012

Effects Of Vegetation, Corridor Width And Regional Land Use On Early Successional Birds On Powerline Corridors, Robert A. Askins, Corrine M. Folsom-O'Keefe, Margaret C. Hardy

Biology Faculty Publications

Powerline rights-of-way (ROWs) often provide habitat for early successional bird species that have suffered long-term population declines in eastern North America. To determine how the abundance of shrubland birds varies with habitat within ROW corridors and with land use patterns surrounding corridors, we ran Poisson regression models on data from 93 plots on ROWs and compared regression coefficients. We also determined nest success rates on a 1-km stretch of ROW. Seven species of shrubland birds were common in powerline corridors. However, the nest success rates for prairie warbler (Dendroica discolor) and field sparrow (Spizella pusilla) were


Increased Variability Of Microbial Communities In Restored Salt Marshes Nearly 30 Years After Tidal Flow Restoration, Anne E. Bernhard, David Marshall, Lazaros Yiannos Jan 2012

Increased Variability Of Microbial Communities In Restored Salt Marshes Nearly 30 Years After Tidal Flow Restoration, Anne E. Bernhard, David Marshall, Lazaros Yiannos

Biology Faculty Publications

We analyzed microbial diversity and community composition from four salt marsh sites that were impounded for 40–50 years and subsequently restored and four unimpounded sites in southeastern Connecticut over one growing season. Community composition and diversity were assessed by terminal restriction fragment length polymorphism (TRFLP) and sequence analysis of 16S ribosomal RNA (rRNA) genes. Our results indicated diverse communities, with sequences representing 14 different bacterial divisions. Proteobacteria, Bacteroidetes, and Planctomycetes dominated clone libraries from both restored and unimpounded sites. Multivariate analysis of the TRFLP data suggest significant site, sample date, and restoration status effects, but the exact causes of these …


The Future Of Blue-Winged And Golden-Winged Warblers In Connecticut, Robert A. Askins Apr 2011

The Future Of Blue-Winged And Golden-Winged Warblers In Connecticut, Robert A. Askins

Biology Faculty Publications

No abstract provided.


Estuarine Nitrifiers: New Players, Patterns And Processes, Anne E. Bernhard, Annette Bollmann Jun 2010

Estuarine Nitrifiers: New Players, Patterns And Processes, Anne E. Bernhard, Annette Bollmann

Biology Faculty Publications

Ever since the first descriptions of ammonia-oxidizing Bacteria by Winogradsky in the late 1800s, the metabolic capability of aerobic ammonia oxidation has been restricted to a phylogenetically narrow group of bacteria. However, the recent discovery of ammonia-oxidizing Archaea has forced microbiologists and ecologists to re-evaluate long-held paradigms and the role of niche partitioning between bacterial and archaeal ammonia oxidizers. Much of the current research has been conducted in open ocean or terrestrial systems, where community patterns of archaeal and bacterial ammonia oxidizers are highly congruent. Studies of archaeal and bacterial ammonia oxidizers in estuarine systems, however, present a very different …


Abundance Of Ammonia-Oxidizing Archaea And Bacteria Along An Estuarine Salinity Gradient In Relationship To Potential Nitrification Rates, Anne E. Bernhard, Zachary C. Landry, Alison Blevins, José R. De La Torre, Anne E. Giblin, David A. Stahl Feb 2010

Abundance Of Ammonia-Oxidizing Archaea And Bacteria Along An Estuarine Salinity Gradient In Relationship To Potential Nitrification Rates, Anne E. Bernhard, Zachary C. Landry, Alison Blevins, José R. De La Torre, Anne E. Giblin, David A. Stahl

Biology Faculty Publications

Abundance of ammonia-oxidizing Archaea (AOA) was found to be always greater than that of ammonia-oxidizing Bacteria along an estuarine salinity gradient, and AOA abundance was highest at intermediate salinity. However, AOA abundance did not correlate with potential nitrification rates. This lack of correlation may be due to methodological limitations or alternative energy sources.


Distribution And Diversity Of Archaeal And Bacterial Ammonia Oxidizers In Salt Marsh Sediments, Nicole S. Moin, Katelyn A. Nelson, Alexander Bush, Anne E. Bernhard Dec 2009

Distribution And Diversity Of Archaeal And Bacterial Ammonia Oxidizers In Salt Marsh Sediments, Nicole S. Moin, Katelyn A. Nelson, Alexander Bush, Anne E. Bernhard

Biology Faculty Publications

Diversity and abundance of ammonia-oxidizing Betaproteobacteria (β-AOB) and archaea (AOA) were investigated in a New England salt marsh at sites dominated by short or tall Spartina alterniflora (SAS and SAT sites, respectively) or Spartina patens (SP site). AOA amoA gene richness was higher than β-AOB amoA richness at SAT and SP, but AOA and β-AOB richness were similar at SAS. β-AOB amoA clone libraries were composed exclusively of Nitrosospira-like amoA genes. AOA amoA genes at SAT and SP were equally distributed between the water column/sediment and soil/sediment clades, while AOA amoA sequences at SAS were primarily affiliated with the …


Historical Information On Bird Distributions Indicates That Mute Swans Were Introduced To North America, Robert A. Askins Mar 2009

Historical Information On Bird Distributions Indicates That Mute Swans Were Introduced To North America, Robert A. Askins

Biology Faculty Publications

No abstract provided.


Do The Size And Landscape Context Of Forest Openings Influence The Abundance And Breeding Success Of Shrubland Songbirds In Southern New England?, Robert A. Askins, Benjamin Zuckerberg, Leah Novak Oct 2007

Do The Size And Landscape Context Of Forest Openings Influence The Abundance And Breeding Success Of Shrubland Songbirds In Southern New England?, Robert A. Askins, Benjamin Zuckerberg, Leah Novak

Biology Faculty Publications

Early successional birds have declined in the northeastern United States due to the regeneration of forest on abandoned farm fields and the suppression of natural disturbances that once provided appropriate habitat. These species have become increasingly dependent on early successional habitats generated by such activities as timber harvesting. Recent approaches of timber harvesting, which range from single-tree harvesting to clearcutting, create forest openings of different sizes and configurations embedded in landscapes with different land use patterns. To assess the importance of forest openings created by timber harvesting for shrubland birds, we surveyed birds on 50m radius plots in 34 harvest …


Conservation Of Grassland Birds In North America: Understanding Ecological Processes In Different Regions, Robert A. Askins, Felipe Chávez-Ramírez, Brenda C. Dale, Carola A. Haas, James R. Herkert, Fritz L. Knopf, Peter D. Vickery Jan 2007

Conservation Of Grassland Birds In North America: Understanding Ecological Processes In Different Regions, Robert A. Askins, Felipe Chávez-Ramírez, Brenda C. Dale, Carola A. Haas, James R. Herkert, Fritz L. Knopf, Peter D. Vickery

Biology Faculty Publications

Many species of birds that depend on grassland or savanna habitats have shown substantial overall population declines in North America. To understand the causes of these declines, we examined the habitat requirements of birds in six types of grassland in different regions of the continent. Open habitats were originally maintained by ecological drivers (continual and pervasive ecological processes) such as drought, grazing, and fire in tallgrass prairie, mixed-grass prairie, shortgrass prairie, desert grassland, and longleaf pine savanna. By contrast, grasslands were created by occasional disturbances (e.g., fires or beaver [Castor canadensis] activity) in much of northeastern North America. The relative …


Judicious Use Of Multiple Hypothesis Tests, Paul J. Roback, Robert A. Askins Feb 2005

Judicious Use Of Multiple Hypothesis Tests, Paul J. Roback, Robert A. Askins

Biology Faculty Publications

When analyzing a table of statistical results, one must first decide whether adjustment of significance levels is appropriate. If the main goal is hypothesis generation or initial screening for potential conservation problems, then it may be appropriate to use the standard comparisonwise significance level to avoid Type 2 errors (not detecting real differences or trends). If, however, the main goal is rigorous testing of a hypothesis, then an adjustment for multiple tests is needed. To control the familywise Type 1 error rate (the probability of rejecting at least one true null hypothesis), sequential modifications of the standard Bonferroni Method, such …


Relationship Between Habitat Area And The Distribution Of Tidal Marsh Birds, Lori K. Benoit, Robert A. Askins Sep 2002

Relationship Between Habitat Area And The Distribution Of Tidal Marsh Birds, Lori K. Benoit, Robert A. Askins

Biology Faculty Publications

To assess the relationship between marsh area and relative abundance of tidal marsh bird species, we surveyed birds on 86 circular plots in 40 salt and brackish tidal marshes in Connecticut. We measured marsh area in two ways: the amount of contiguous marsh vegetation not interrupted by broad barriers (>500 m of open water or >50 m of upland habitat) and by narrow barriers (>30 m of open water or >10 m upland). We determined the relationship between marsh area and the relative abundance of particular species (mean number of individuals per survey plot) with linear or logistic …


Helping Shrubland Birds, Robert A. Askins Jan 2002

Helping Shrubland Birds, Robert A. Askins

Biology Faculty Publications

Dr. Askins argues that shrublands were part of the pre-Colonial landscape in Connecticut, so it's logical to create forest openings to help shrubland birds.


Sustaining Biological Diversity In Early Successional Communities: The Challenge Of Managing Unpopular Habitats, Robert A. Askins Jul 2001

Sustaining Biological Diversity In Early Successional Communities: The Challenge Of Managing Unpopular Habitats, Robert A. Askins

Biology Faculty Publications

No abstract provided.


Differences In Bird Communities On The Forest Edge And In The Forest Interior: Are There Forest-Interior Specialists In Japan?, Reiko Kurosawa, Robert A. Askins Nov 1999

Differences In Bird Communities On The Forest Edge And In The Forest Interior: Are There Forest-Interior Specialists In Japan?, Reiko Kurosawa, Robert A. Askins

Biology Faculty Publications

Most North American bird species that are less successful in small forests than in large forests, are forest-interior specialists that winter in the tropics. These species have declined in small forests because of high rates of nest predation and brood parasitism near the forest edge. To determine whether migratory forest-interior specialists are also important components of bird communities in Japan, we surveyed bird populations on plots at the edge and in the interior of deciduous forests in Hokkaido and Kyoto. Surveys were conducted during the breeding season in forest fragments using the point count method. We calculated edge indices for …


History Of Grassland Birds In Eastern North America, Robert A. Askins Sep 1999

History Of Grassland Birds In Eastern North America, Robert A. Askins

Biology Faculty Publications

Until recently the severe decline in the populations of many species of grassland birds in eastern North America has aroused relatively little concern or conservation action. This response appears to be rooted in the perception that grassland birds invaded the East Coast from western grasslands after European settlers cleared the forest. Detailed historical accounts and analysis of pollen deposits, however, show that open grasslands existed on the East Coast of North America at the time of European settlement. Extensive grasslands resulted from burning and agricultural clearing by Native Americans. Natural disturbances, such as wildfire and beaver (Castor canadensis) activity, produced …


Reproductive Success Of Ospreys At Two Sites In Connecticut, Donna Christine O'Neill, Robert A. Askins Jul 1998

Reproductive Success Of Ospreys At Two Sites In Connecticut, Donna Christine O'Neill, Robert A. Askins

Biology Faculty Publications

Nest success rates and rates of fish delivery to nests were determined for two large Osprey populations in COlmecticut, one at Groton Reservoir, Groton, and one at Great Island, Old Lyme, during 1996 and 1997. Between 1993 and 1996 these Osprey populations had substantially different rates of nest success. Great Island Ospreys fledged few young while Groton Reservoir Ospreys had good nest success. During 1997, however, fledging rates were similar at the two sites. In 1996, low nest success at Great Island 'resuited from high predation rates, probably due to raccoons. The higher nest success rate at this site in …


Conservation Of Grassland Birds In The Northeast, Robert A. Askins Apr 1995

Conservation Of Grassland Birds In The Northeast, Robert A. Askins

Biology Faculty Publications

No abstract provided.


Open Corridors In A Heavily Forested Landscape: Impact On Shrubland And Forest-Interior Birds, Robert A. Askins Jul 1994

Open Corridors In A Heavily Forested Landscape: Impact On Shrubland And Forest-Interior Birds, Robert A. Askins

Biology Faculty Publications

In eastern North America, remnant patches of forest surrounded by open habitat constitute unfavorable habitat for many species of migratory forest birds because of high rates of nest predation and cowbird parasitism. Although most evidence for this relationship comes from 'forest islands' surrounded by residential or agricultural land, even forest patches isolated from other forests by narrow open corridors such as roads and powerline rights-of-way seem to show this pattern. Productive habitat for migratory birds can be maintained by consolidating corridors and routing them along the periphery of forests to retain as much continuous forest as possible. Consolidation of open …


Population Studies Of Migratory Birds In Virgin Islands National Park, Robert A. Askins, David N. Ewert Apr 1992

Population Studies Of Migratory Birds In Virgin Islands National Park, Robert A. Askins, David N. Ewert

Biology Faculty Publications

The majority of the individual songbirds nesting in the deciduous forests of eastern North America migrate to the West Indies, Central America and South America during the winter. They typically spend more than six months in tropical winter habitats. Until recently relatively little was known about their habitat requirements during the winter, but increasing concern about declining pcpulations of many migratory songbirds combined with widespread alarm about the rapid destruction of tropical forests has led to a flurry of research on this subject (Terborgh, 1989; Askins et al. 1990). In 1987 we initiated a study of the ecology and behavior …