Mechanistic Examination Of Protist-Mediated Plant Growth Through The Comparative Development Of Medicago Truncatula, Shane Connolly

University Scholar Projects

Protists are known to increase plant growth through two main mechanisms: the microbial loop and the alteration of the root microbiome. The microbial loop is a nutrient recycling method in which protists provide inorganic nitrogen ions to the plant. Alteration of root microbiome leads to the removal of plant pathogens and shifting communities towards plant growth-promoting bacteria (PGPB). This study aimed to elicit which mechanism could produce the largest boost in shoot weight for Medicago truncatula. A series of microcosm experiments were explored in which M. truncatula was grown with variable microbiome structures to allow for mechanism differentiation. The …

Mark-Recapture Study And Habitat Assessment For The Northern Metalmark Butterfly, Calephelis Borealis (Lepidoptera: Riodinidae), Weston J. Henry, Kristian S. Omland, Henry Frye, Wagner L. David

EEB Articles

Background: The northern metalmark (Calephelis borealis), is an exceedingly local, globally rare butterfly that is declining across the Midwestern and Northeastern USA. The principal stressors driving colony losses include afforestation and invasive plants that crowd out its larval hostplant (Packera ovata) and nectar resources.

Aims/Methods: To better understand its declines and guide restoration efforts, we 1) performed a mark-recapture study in Connecticut to document population trends where we were actively managing vegetation; 2) conducted a range-wide survey for evidence of phylogeographic structure, using cytochrome oxidase (CO1); 3) investigated abundance determinants of its larval foodplant, Packera ovata …

Stomach Contents And Stable Isotope Analysis Reveal Ontogenetic Shifts And Spatial Variability In Brama Australis Diet, Sebastian A. Klarian, Eric T. Schultz, María Francisca Hernández, Juan Antonio Valdes, Francisco Fernandoy, Mónica Barros, Sergio Neira, Hugo Arancibia

EEB Articles

Many marine fisheries rely on production and energy flow in the pelagic zone, thus sustainable management of exploited pelagic fishes benefits from insight into temporal, spatial and ontogenetic variability in the trophic ecology of these species. Here we analyze stomach contents and stable isotopes to reveal spatial variability (focusing on two fishing grounds, north and south of an oceanographic barrier in the Pacific Ocean) and ontogenetic changes (contrasting immature and mature) in Southern Ray’s Bream (Brama australis) diet composition in Chilean waters. Stomach contents analysis indicated that euphausiids were predominant components of the diet in both fishing grounds and ontogenetic …

Ovarian Dynamics And Fecundity Regulation In Blueback Herring, Alosa Aestivalis, From The Connecticut River, Us, Foivos Alexandros Mouchlianitis, Eric T. Schultz, Thassya C. Dos Santos Schmidt, Justin P. Davis, Kostas Ganias

EEB Articles

We analyzed ovarian dynamics of anadromous blueback herring, Alosa aestivalis, in Connecticut River with the principal aim of exploring oocyte recruitment and how it shapes the fecundity pattern. We examined the oocyte release strategy and analyzed spawning cyclicity by linking oocyte growth to the degeneration of postovulatory follicles. Females were accordingly classified as pre-spawners, early and late active spawners, and oocyte recruitment intensity was compared among the different spawning phases. Oocyte recruitment occurred continuously and in parallel with spawning activity, a pattern which is diagnostic of indeterminate fecundity. However, both fecundity and oocyte recruitment intensity progressively decreased (tapered) throughout …

Bio-Economic Outcomes Under Alternative Management Strategies With Human Choice And Behavior: Modeling Tautog And Anglers' Preferences, Eric T. Schultz, Zhenshan Chen, Pengfei Liu, Stephen Swallow, Jacob M. Kasper

EEB Articles

Key findings

• There was relatively strong support for slot limits, and roughly comparable support for status quo management, among anglers fishing for Tautog in Long Island Sound.
• Respondents were not in favor of a total moratorium on fishing for Tautog.
• Providing survey respondents information on how different management scenarios will affect fishing in the future had little detectable impact on fishing preferences.
• Respondents expected to fish less in the future if a wide slot limit is imposed or if status quo management is maintained, but expected no change in effort if a narrow slot limit is imposed.
• Changes in regulations …

Deicing Salts Influence Ranavirus Outbreaks In Wood Frog (Lithobates Sylvaticus) Tadpoles, Sarah Jacobson

Honors Scholar Theses

Ecosystems are increasingly being exposed to anthropogenic stressors that could make animals and thus populations more susceptible to disease. For example, the application of deicing salts to roads is increasing in the northeastern United States. Chronic stress that larval amphibians experience when living in vernal pools with high salinity may alter their susceptibility to ranavirus, a pathogen responsible for mass mortality events worldwide. This project quantifies the effects of road salts and ranavirus exposure on larval wood frog (Lithobates sylvaticus) growth and survival. Using outdoor mesocsoms, we raised wood frog tadpoles in salt treatments and then exposed them …

Zebra Mussel (Dreissena Polymorpha) Affects The Feeding Ecology Of Early Stage Striped Bass (Morone Saxatilis) In The Hudson River Estuary, Michael G. Smircich, David L. Strayer, Eric T. Schultz

EEB Articles

Variability in the feeding ecology of young fishes over short and long time scales in estuaries is likely to affect population dynamics. We studied 14 years of early stage Striped Bass feeding ecology in the Hudson River Estuary over a 25-year time span, including years in which invasive zebra mussels markedly altered energy flow within the estuary. We predicted that feeding success would be low and that diet composition would be altered during years of high zebra mussel impact, particularly in upriver locations where mussels occur. Feeding success in the short term was indicated by volume of gut contents and …

Partners In Spread Prevention, Nancy C. Balcom

Wrack Lines

Working together to stop the spread of aquatic invasive species.

An Approach For Use Of Dual Frequency Identification Sonar (Didson) To Quantify Behavioral Aspects Of Piscivory At Ecologically Relevant Time And Space Scales, Victoria E. Price

Master's Theses

Predator-prey interactions of large vagile fishes are difficult to study in the ocean due to limitations in the space and time requirements for observations. Small-scale direct underwater observations by divers (<10m >radius) and large-scale hydroacoustic surveys (10s - 100s km2) are traditional approaches. However, large piscivorous predators identify and attack prey at the scale of meters to tens of meters. Dual- Frequency Identification Sonar, or DIDSON, is a high-resolution acoustic camera operating in the MHz range that provides detailed continuous video-like imaging of objects out to 30 m range. This technology can be used to observe predator-prey interactions at ecologically …

Estimating Covariation Between Vital Rates: A Simulation Study Of Connected Vs. Separate Generalized Linear Mixed Models (Glmms), Margaret Ek Evans, Kent E. Holsinger

EEB Articles

Covariation between vital rates is recognized as an important pattern to be accounted for in demographic modeling. We recently introduced a model for estimating vital rates and their covariation as a function of known and unknown effects, using generalized linear mixed models (GLMM’s) implemented in a hierarchical Bayesian framework (Evans et al. 2010). In particular, this model included a model-wide year effect (YEAR) influencing all vital rates, which we used to estimate covariation between vital rates due to exogenous factors not directly included in the model. This YEAR effect connected the GLMMs of vital rates into one large model; we …

Theory And Design Of Nature Reserves, Kent E. Holsinger

EEB Articles

Notes that accompany a lecture on reserve design when I taught a graduate level course in conservation biology. These notes provide an introductory overview to the theory and design of nature reserves.

Environmental And Endogenous Factors Influencing Emigration In Juvenile Anadromous Alewives, Benjamin I. Gahagan, Eric T. Schultz, Katie E. Gherard

EEB Articles

We analyzed juvenile anadromous alewife migration at Bride Lake, a coastal lake in Connecticut, during summer 2006 and found that migration on 24-hour and seasonal timescales was influenced by conditions of the environment and characteristics of the individual. To identify environmental cues of juvenile migration, we continuously video recorded fish at the lake outflow and employed information-theoretic model selection to identify the best predictors of daily migration rate. More than 80% of the approximately 320,000 juveniles that migrated from mid-June to mid-August departed in three pulses lasting one or two days. Pulses of migration were associated with precipitation events, transient …

Temporal Shifts In Demography And Life History Of An Anadromous Alewife Population In Connecticut, Justin P. Davis, Eric T. Schultz

EEB Articles

Populations of anadromous alewives (Alosa pseudoharengus) are declining throughout much of their range, particularly in southern New England where fishery moratoriums have recently been instituted in three states. The alewife run at Bride Brook, a coastal stream in East Lyme, Connecticut, was studied from 2003-06 to assess shifts in demography and life history. Annual censuses of abundance, along with sampling for size, age, and spawning history structure were conducted. These data were compared to similar data in 1966-67 at this site. Recent alewife runs at Bride Brook featured lower abundance and younger, smaller fish that were less likely to be …

Integrating Fluvial Geomorphology And Stream Ecology: Processes Shaping The Distribution Of Freshwater Mussels In Connecticut, Piyumi T. Obeysekara, Eric T. Schultz, Melinda Daniels, Jason Vokoun

EEB Articles

No abstract provided.

Assessment Of River Herring And Striped Bass In The Connecticut River: Abundance, Population Structure, And Predator/Prey Interactions, Justin P. Davis, Eric T. Schultz, Jason Vokoun

EEB Articles

Populations of anadromous alewife Alosa pseudoharengus and blueback herring A. aestivalis, collectively referred to as river herring, have declined in the Connecticut River. An explanatory hypothesis for these declines is that predation pressures have increased as a result of recent increases in abundance of sympatric striped bass Morone saxatilis. We sampled river herring and striped bass from the stretch of the Connecticut River between Wethersfield, CT and Holyoke, MA during the vernal migration seasons of 2005-2008. The objectives of the sampling program were to assess abundance, temporal/spatial distribution, and population structure of both river herring and striped bass, …

Estimating Predation On Declining River Herring: Tag-Recapture Study Of Striped Bass In The Connecticut River, Eric T. Schultz, Justin P. Davis, Jason Vokoun

EEB Articles

Populations of anadromous alewife Alosa pseudoharengus and blueback herring Alosa aestivalis, collectively referred to as river herring, have declined in the Connecticut River. A hypothesis for why river herring have declined is that predation pressures have increased associated with recent increases in abundance of striped bass Morone saxatilis. Information on striped bass abundance, size structure, and consumption rates are required to test this hypothesis. This study was designed to provide estimates of striped bass population size in the Connecticut River during the spring migration season, via an intensive mark-recapture exercise and either an open or robust mark-recapture model. …

A Sex Difference In Seasonal Timing Of Birth In A Livebearing Fish, Eric T. Schultz

EEB Articles

Sex differences in seasonal timing include differences in hatch- or birth-date distribution and differences in the timing of migration or maturation such as protandrous arrival timing (PAT), which is early male arrival at breeding sites. I describe a novel form of protandrous arrival timing, as a sex difference in birth-date distribution in a live-bearing fish (Dwarf Perch, Micrometrus minimus). In this species, birth coincides with arrival at breeding sites because newborn males are sexually active. A series of samples of pregnant females and young of year was collected in Tomales Bay, CA. I analyzed the daily age record in otoliths …

Determining Winter Flounder Spawning Sites In Two Connecticut Estuaries, Eric T. Schultz, Jose J. Pereira, Peter J. Auster

EEB Articles

Winter flounder (Pseudopleuronectes americanus) come inshore during the late winter and early spring to lay their eggs in shallow bays and estuaries along the coast. Unlike most fish eggs, which are buoyant, these eggs are demersal and sink to the seafloor. This makes them vulnerable to burial from various types of natural and human caused disturbances (e.g., storms, mobile fishing gear, maintenance dredging). Our objective was to map spawning areas in two harbors and search for generalities among these sites that would allow us to predict where winter flounder might spawn in other areas. This would allow managers to avoid …

Anadromous Rainbow Smelt And Tomcod In Connecticut: Assessment Of Populations, Conservation Status, And Need For Restoration Plan, Heather A. Fried, Eric T. Schultz

EEB Articles

(beginning of rainbow smelt executive summary)

Evidence indicates that anadromous rainbow smelt (Osmerus mordax) populations in Connecticut and elsewhere in the northeast United States have severely declined. Several sampling programs have documented declines in Connecticut’s smelt populations over the last three decades (Marcy 1976a, Marcy 1976b, Millstone Environmental Laboratory 2005). Similar declines have also been documented in the Hudson River (ASA Analysis & Communication 2005) and in Massachusetts (personal communication, Brad Chase, MA Division of Marine Fisheries 2004). Recreational and commercial fisheries in the region for this species have virtually ceased (Blake and Smith 1984). The Connecticut Fish Advisory Committee …

Assessment Of Anadromous Alewife And Blueback Herring Populations In Connecticut Coastal Streams And Connecticut River Tributaries, Justin P. Davis, Eric T. Schultz

EEB Articles

Alewife (Alosa pseudoharengus) and blueback herring (A. aestivalis) occur in anadromous populations that have a largely overlapping distribution from Florida to Newfoundland (Loesch 1987). Anadromous populations of these species are commonly collectively referred to as “river herring”. Adults inhabit coastal shelf waters until sexual maturity is reached at age 3-5 (Neves 1981). Sexually mature individuals make spawning migrations, commonly referred to as “runs”, into freshwater systems during spring months (Loesch 1987). Spawners can survive and return to spawn in subsequent years (Mullen et al. 1986). Juveniles reside in freshwater for 3-7 months, at which time they undertake a gradual migration …

Decreased Reproductive Investment Of Female Threespine Stickleback Gasterosteus Aculeatus Infected With The Cestode Schistocephalus Solidus: Parasite Adaptation, Host Adaptation, Or Side Effect?, Eric T. Schultz, Michelle Topper, David C. Heins

EEB Articles

Parasitic infections may cause alterations in host life history, including changes in reproductive investment (absolute amount of energy allocated to reproduction) and reproductive effort (proportion of available energy allocated to reproduction). Such changes in host life history may reflect: 1) a parasite tactic: the parasite adaptively manipulates energy flow within the host so that the host is induced to make a reduction in reproductive effort and reproductive investment, making more energy available to the parasite; 2) no tactic: there is no change in host reproductive effort and reproductive investment simply decreases as a side effect of the parasite depleting host …

The Dynamics Of Bay Anchovy In The Hudson River Estuary: Process-Oriented Studies And Long-Term Changes, Eric T. Schultz, Kamazima M. M. Lwiza, John R. Young, Kyle J. Hartman, R. C. Tipton

EEB Articles

We review three areas of recent research on Hudson River bay anchovy. One focus has been the along-estuary movement of early life stages. A cohort analysis of samples collected in a spatiotemporally extensive monitoring program has confirmed that early-stage anchovy migrate up-estuary, at an estimated rate of 0.6 km/d. Complementary fine-scale field sampling was designed to clarify behaviors that effect the migration. This work found that early-stage anchovy can show preferences for depth and can conduct periodic vertical migration. To determine whether these behaviors were sufficient to produce up-estuary migration, larval flux and velocity were estimated. These estimates were consistent …

The Essentials On Estuarine Fish Habitat, Its Evaluation And Protection By Federal Fisheries Law, Eric T. Schultz, Michael Ludwig

EEB Articles

No abstract provided.

Distribution, Habitat Use, Growth, And Condition Of A Native And An Introduced Catfish Species In The Hudson River Estuary, Stephen M. Jordan, Robert M. Neumann, Eric T. Schultz

EEB Articles

White catfish (Ameiurus catus) is native to the Hudson River and is now coexisting with the recently established channel catfish (Ictalurus punctatus). These species were sampled from four freshwater reaches and four habitat types of the Hudson River estuary to assess whether the two species overlapped in their habitat use, and whether any impact on the native species was evident. Catfishes were sampled in 1998 and 1999 using baited hoop nets (N = 708 net nights). Catch-per-unit-effort (CPUE, number of fish per net night; total catch = 368) of white catfish was significantly different among reaches …

Mechanisms Promoting Upriver Transport Of Two Species Of Larval Fish In The Hudson River Estuary (Usa), Eric T. Schultz, Kamazima M M Lwiza, Megan C. Fencil, Jennifer M. Martin

EEB Articles

Bay anchovy Anchoa mitchilli and naked goby Gobiosoma bosc larvae have been reported to move up-estuary. In the present study, we examined depth preferences and periodic vertical movements that might promote such along-estuary transport in these 2 species. We conducted 2 cruises of 3 d each in the Hudson River estuary, USA. The cruises were 1 wk apart, coinciding with spring and neap tides. We sampled every 2 h with an ichthyoplankton trawl to permit tests of time, depth, and lateral position on larval concentration. We also collected data on water-column structure with a CTD, and current velocity with an …

Recruitment Of Coral Reef Fishes To Bermuda: Local Retention Or Long-Distance Transport?, Eric T. Schultz, Robert K. Cowen

EEB Articles

The benthic marine fauna of isolated oceanic islands may be self-seeding, or alternatively may be continually supplied with recruits advected from elsewhere by ocean currents. Estimates of the time required for transport of larvae from elsewhere was combined with information on the larval durations of fishes inhabiting the reefs of Bermuda, to test the hypothesis that other populations are sources for recruits to Bermuda. Specifically, we tested the prediction that transport occurs frequently enough to sustain local populations of reef fishes. Transport of larvae was modelled as a 2-step process in several numerical simulations. The first step of transport was …

Historic Trends In The Distribution And Populations Of Estuarine Marsh Birds Of The Connecticut River, Robert J. Craig

Storrs Agricultural Experiment Station

No abstract provided.