Graduate studentship: The Ohio State University, Columbus, OH, USA

Graduate Positions in Aquatic Ecology

Hood Lab, Aquatic Ecology Laboratory, Department of Evolution, Ecology, and Organismal Biology, The Ohio State University

 The Hood Lab (www.hoodaquaticslab.wordpress.com) is recruiting up to two MS or PhD students to work on two projects focused on: (1) how interactions between harmful algal blooms and hypoxia shape zooplankton communities and food web dynamics in Lake Erie and (2) the role stream nutrient cycles and metabolism play in shaping phosphorus exports from agricultural landscapes to Lake Erie.

 The ideal candidates will be highly motivated and honest, with strong quantitative skills, an interest in ecosystem ecology, and a background in ecology and/or aquatic science. I seek to maintain a productive, diverse, and team-orientated lab group and especially encourage students from under-represented groups to consider joining the lab. A Master’s degree is preferred for Ph.D. students, but not required. Financial support is available through a combination of research assistantships, competitive fellowships, and teaching assistantships.

 If interested, please email Jim Hood (hood.211@osu.edu) a single PDF containing (1) a statement of interest, (2) a CV, and (3) contact information for your three references. On 21 October, I will begin reviewing candidate applications and ultimately invite selected applicants to apply.

Diurnal variations in sulfur transformations at the chemocline of a stratified freshwater lake

Authors

Khoren Avetisyan,Werner Eckert, Alyssa J. Findlay, Alexey Kamyshny Jr.

In order to characterize biogeochemical sulfur cycling in the metalimnion of a thermally stratified freshwater lake, we followed changes in the concentrations and isotopic composition of sulfur species during a 24-h period, during which the chemocline oscillated at an amplitude of 5.3 m due to internal wave activity. Hourly sampling at a fixed depth (17.1 m) enabled study of redox changes during the transition from oxic to sulfidic conditions and vice versa. The oxidation–reduction potential, pH, conductivity and turbidity correlated linearly with the water temperature (a proxy for depth relative to the chemocline). The highest concentrations of thiosulfate and sulfite were detected approximately 2.5 m below the chemocline. Concentrations of zero-valent sulfur increased ~ 10 fold when the chemocline rose into the photic zone due to phototrophic sulfide oxidation. Triple isotopic composition of sulfur species indicates a shift with depth from values typical for sulfate reduction right below the chemocline to values which may be explained by either sulfate reduction alone or by a combination of microbial sulfate reduction and microbial sulfate disproportionation. We conclude that consumption of hydrogen sulfide at the chemocline of Lake Kinneret is controlled by the combination of its chemical and/or chemotrophic oxidation to sulfur oxoanions and predominantly phototrophic oxidation to zero-valent sulfur.

Variable impacts of contemporary versus legacy agricultural phosphorus on US river water quality

Authors

Sarah M. Stackpoole, Edward G. Stets, and Lori A. Sprague

Phosphorus (P) fertilizer has contributed to the eutrophication of freshwater ecosystems. Watershed-based conservation programs aiming to reduce external P loading to surface waters have not resulted in significant water-quality improvements. One factor that can help explain the lack of water-quality response is remobilization of accumulated legacy (historical) P within the terrestrial-aquatic continuum, which can obscure the beneficial impacts of current conservation efforts. We examined how contemporary river P trends (between 1992 and 2012) responded to estimated changes in contemporary agricultural P balances [(fertilizer + manure inputs)—crop uptake and harvest removal] for 143 watersheds in the conterminous United States, while also developing a proxy estimate of legacy P contribution, which refers to anthropogenic P inputs before 1992. We concluded that legacy sources contributed to river export in 49 watersheds because mean contemporary river P export exceeded mean contemporary agricultural P balances. For the other 94 watersheds, agricultural P balances exceeded river P export, and our proxy estimate of legacy P was inconclusive. If legacy contributions occurred in these locations, they were likely small and dwarfed by contemporary P sources. Our continental-scale P mass balance results indicated that improved incentives and strategies are needed to promote the adoption of nutrient-conserving practices and reduce widespread contemporary P surpluses. However, a P surplus reduction is only 1 component of an effective nutrient plan as we found agricultural balances decreased in 91 watersheds with no consistent water-quality improvements, and balances increased in 52 watersheds with no consistent water-quality degradation.

Methane emissions from aqueous sediments are influenced by complex interactions among microbes and environmental factors: A modeling study

Authors

Zhanfei He, Shuyu Xu, Yuanhai Zhao, Xiangliang Pan

Methane fluxes from aqueous sediments strongly influence global atmospheric methane. However, many questions still puzzle researchers; for example, why are some unstable sediments atmospheric methane sinks? In this study, a biofilm model originally developed for wastewater treatment was modified to simulate the microbial kinetics and substance conversions in aqueous surface sediments. The model was validated by the experimental data and could predict chemical profiles and microbial distributions in sediments. The model revealed complicated interactions between different microbial communities and environmental factors, including competition between aerobic methane-oxidizing bacteria, nitrite-dependent anaerobic methane-oxidizing bacteria, and anaerobic ammonia-oxidizing bacteria. The results of model simulations showed that the effects of environmental factors, especially dissolved oxygen and ammonia in overlying water, on methane fluxes are very complicated. Rapid environmental changes (which can be caused by tide, day-night alternation, or zoobenthic and human activity) and intensive competition between microbes greatly affected methane fluxes and resulted in alternation between atmospheric methane source and sink in unstable sediments. This study extends the application of a wastewater treatment model to ecological studies of microbial interactions in natural sediments and explains some problems that might be difficult to resolve by using experimental methods.

Variation in phytoplankton pigment composition in relation to mixing conditions in temperate South-Central Chilean lake

Authors

Evelien Van de Vyver, Jeroen Van Wichelen, Pieter Vanormelingen, Wim Vannieuwenhuyze, Ilse Daveloose, Rixtde Jong, Reinhoudde Blok, Roberto Urrutia, Bjorn Tytgat, Elie Verleyen, Wim Vyverman

Thermal lake properties are sensitive to changes in windiness and precipitation, and affect the physical and chemical properties of the water column, which in turn control phytoplankton dynamics and primary production. We assessed the use of phytoplankton pigment profiling as a potential indicator of stratification conditions in temperate lakes in South-Central Chile. Spring and early summer phytoplankton pigment profiles and the physical and chemical limnology were analyzed in 43 lakes ranging in size, depth, altitude and catchment characteristics. Eleven lakes were sampled during both seasons. Variation in pigment composition between lakes was primarily related to stratification conditions and mixed layer light availability at the time of sampling. The dinoflagellate marker pigment peridinin was more abundant in more deeply mixed lakes with a lower mean irradiance, while chlorophyte pigments (chlorophyll b, lutein) tended to be higher in shallow (high-light) epilimnia. Diatom and chrysophyte pigments (fucoxanthin) dominated under less thermally stable and more variable light conditions. Cyanobacteria pigments (zeaxanthin), probably derived from picocyanobacteria, were relatively more abundant in very transparent, low productive lakes. Lakes in close vicinity of active volcanoes were enriched in silica and PO₄-P concentrations and characterised by elevated chlorophyte marker pigments. Within strongly stratified lakes, in which the euphotic zone extended in the hypolimnion, cryptophyte pigments (alloxanthin) characterized the deep chlorophyll maxima while the epilimnion was consistently enriched with the photoprotective xanthophyll-cycle pigment violaxanthin. We conclude that major algal groups, represented by pigment biomarkers, are largely driven by changes in lake water column stratification and related mixed layer light availability as well as nutrient concentrations in temperate Chilean freshwater lakes.

Strain-specific responses of toxic and non-toxic Microcystis aeruginosa to exudates of heterotrophic bacteria

Authors

Leighannah Akins, Joseph Ortiz, Laura G. Leff

Although the cyanobacterium Microcystis is colonial during water blooms, isolated Microcystis strains become unicellular in culture. Studies indicate that heterotrophic bacteria can promote Microcystis colonies in culture, but little is known about the underlying mechanism or how widespread it is among bacteria. This study investigated the identity and colony-promoting effects of bacteria isolated from the 2014 Microcystis bloom in Lake Erie. Isolates were classified by their 16S rRNA gene sequences. Toxic and non-toxic cultures of M. aeruginosa were exposed to exudates of bacterial isolates, and their morphology, polysaccharide content, and reflectance spectra were compared to those of M. aeruginosa control cultures. Six isolates belonging to three genera enhanced the frequency or size of M. aeruginosa colonies in cultures where a dialysis barrier prevented direct contact between heterotrophic cells and M. aeruginosa cells. Toxic and non-toxic M. aeruginosa strains differed in how their morphology and optical properties responded to treatment. This study demonstrates that heterotrophic bacteria can promote colonial morphology in Microcystis without making physical contact with the Microcystis cells, as well as the first to indicate that toxic and non-toxic strains of the same morphospecies have different morphological and optical responses.

Sediment methane dynamics along the Elbe River

Authors

Adam Bednařík, Martin Blaser, Anna Matoušů, Michal Tušer, Prem Prashant Chaudhary, Karel Šimek, Martin Rulík

Methane (CH₄) is an important atmospheric trace gas mostly released from wet anoxic soils and sediments. While many studies have focused on relatively homogenous environments like rice fields and lake sediments, the changing contribution of heterogeneous sediments e.g. along the longitudinal profile of a rivers has not been covered very frequently. Here we investigated sediment samples from 11 locations of the Elbe River. Sediments were incubated to measure methanogenic/methanotrophic potentials and contribution of individual methanogenic pathways using isotope analysis of δ¹³C. Additionally, we determined the diversity of the methanogenic communities (analysis of T-RFLP targeting the mcr-A gene in the sediment samples), while abundances of archaea, methanogens and methanotrophs were determined by qPCR. The CH₄ production was detected in six samples (out of 11 examined) and ranged from 0.12 to 644.72 nmol gDW^-1 d^-1. Methanotrophy was found in all examined sediment samples and ranged from 654 to 10,875 nmol gDW^-1 d^-1. Abundance of methanogens and methanotrophs (Mcr-A and pmo-A gene copy numbers) was not significantly different and quite stable around 10⁶ to 10⁷ copies gDW^-1. The group specific qPCR showed high fluctuations, while the highest counts were reported for Methanomicrobiales and Methanosarcinales (10⁵ to 10⁸ copies per gram dry sediment), followed by Methanobacteriales (10³ to 10⁵ copies per gram dry sediment). A significant proportion of unidentified methanogens was found in almost every locality. Isotope analysis of δ¹³C showed that (CH₄) is produced mainly by hydrogenotrophic methanogens. We see no trend in the studied parameters along the Elbe River. The molecular data showed no spatial characteristics, while we found hotspots of the measured CH₄ processes (CH₄ production and oxidation) due to other local driving factors (e.g. carbon content). Thus, out results indicate that the observed variability of the CH₄ production and oxidation rates is only indirectly linked to the presence or quantities of different microbial guilds.

Postdoc (Phenotyping Rubisco in aquatic organisms), University of the Balearic Islands, Spain

2–years postdoc position at the University of the Balearic Islands, under the project MARISCO “Phenotyping Rubisco in aquatic organisms: evolutionary drivers, molecular mechanisms and ecological consequences”

The aim of the project is to study the performance of Rubisco in targeted phylogenetic branches along the evolution of photosynthetic organisms

Duration: 2 years, potentially longer depending on funding.

Starting date: end of 2019 or by agreement.

Interested applicants should send their CV plus motivation letter to Concepción Íñiguez (c.iniguez@uib.es <mailto:c.iniguez@uib.es>) or Jeroni Galmés (jeroni.galmes@uib.cat <mailto:jeroni.galmes@uib.cat>).

Applications close on November 30th.

The candidate is expected to have a PhD in one of the following subjects: Biology, Biochemistry, Physiology, Ecology, Microbiology, and/or related topics. Background in bioinformatic analysis, genomic data and familiarity with meta-analysis is also expected. Demonstrated ability in writing and scientific communication, with a sufficient number of publications in relevant positions is a requisite.

Competencies which will constitute an advantage during the selection are:

–        Experience in Rubisco biochemistry.

–        Experience of working with phytoplankton and aquatic macrophytes.

–        Experience of working with extremophyles.

Additional skills:

Capacity to take the initiative, be creative and to manage own progress with accuracy.

Good ability to work independently in a cross disciplinary environment.

Good communication skills and a good command of written and spoken English is required.

Research Assistant (Aquatic Ecology), University of Maryland, MD, USA

Field Research Technician Position open

A wetland ecology research technician position is available through the University of Maryland Palmer Lab. This is full time with benefits and is available immediately or until filled. The field sites are in Maryland but the research is part of an NSF funded project with a dynamic team including: Palmer Lab members, Va Tech scientists Erin Hotchkiss, Durelle Scott, Daniel McLaughlin AND Univ Alabama’s Nate Jones. The project focuses on wetlandscape hydrology and carbon biogeochemistry.

Full description below:

RESEARCH ASSISTANT (TECH) POSITION IN AQUATIC ECOLOGY

Position: Full-time Research Assistant position available to help conduct ongoing research in wetlands and streams of the eastern shore, MD. The focus of the research program is to explore hydrological connectivity and carbon dynamics in seasonally inundated wetlands (Delmarva Bays). Successful applicant would be part of a dynamic team of researchers and students. Duties: The researcher will conduct field work in wetlands and streams, and laboratory work at the University of Maryland (College Park). Specific duties include but are not limited to: water sample and data collection, stormflow sampling, maintenance and use of environmental sensors, and laboratory analysis of dissolved, particulate, and gas constituents.  For more on the overall project see http://www.PalmerLab.Umd.Edu

Required Qualifications:

An MS degree in environmental science-related field or a BS plus at least one year of work experience in biogeochemistry or hydrology.

Previous experiences conducting field work and is willing to work in harsh weather conditions; must be able to perform physical demanding tasks such as carrying heavy field equipment.

Laboratory experience, particularly with sensitive analytical instruments.

Data management skills including familiarity with QA/QC, Microsoft Office products (i.e., Word, Excel, Access) and, ideally, R statistical software.

Excellent written, oral, and organizational skills.

Willing to occasionally work evenings, early mornings, and weekends; reliable automobile transportation and clean driving license is required.

Desired Qualifications:

Degree in field focused on aquatic ecosystems.

Previous experiences in measuring hydrological parameters, collection and analysis of water and gas chemistry samples, and installing, downloading and maintenance of in situ, environmental sensors.

Salary: The University of Maryland offers a competitive salary dependent upon qualifications. Duration of appointment is for at least one year with the possibility of two additional years contingent upon performance evaluation and continued project funding. A comprehensive fringe benefit package is also available.

To Apply: Send application to Dr. Michael Williams (miwillia@umd.edu). Application materials include: i) letter describing prior work experience as it pertains to above qualifications; ii) resume/CV; and contact information for two references.

Postdoc (Functional genomics and metabolomics of marine photosymbioses), University of Colodaro Boulder, CO, USA

Job Summary:

The Li Lab, in the Department of Ecology and Evolutionary Biology, University of Colorado Boulder, is hiring a Post-Doctoral Associate to work on functional genomics and metabolomics of marine photosymbioses. This project aims to use multiple marine invertebrate-algal symbiotic systems to study the genetic and molecular mechanisms behind the host-symbiont nutrient exchange process.

Minimal Qualifications:

-PhD in Biology, Evolution, Molecular Biology or similar areas -Expertise with generating and analyzing genomic/metabolomics data -Proficient in R, Python, and other related bioinformatics tools -Excellent writing and communication skills -Independent, collaborative and motivated

Preferred Qualifications:

-Understanding of phylogenetics, marine ecology, and invertebrate  evolution -Experience with genome assembly -Experience working with symbiotic systems -Field work experience in marine habitats

About us:

We offer a supportive, diverse and intellectually stimulating environment, with great opportunities for professional development and outreach. This is a full-time, 12-month position based at Boulder, Colorado, renewable for multiple years (2+) conditional on performance. The position is available immediately but starting date is negotiable. Salary will follow NIH/NSF guidlines (50-52k/yr based on experience) with full benefits.

If interested, please email Dr. Jingchun Li (jingchun.li@colorado.edu) a single PDF including: i) a motivation letter explaining your research interests and qualifications, ii) your CV, iii) contact information of three references.  For full consideration, please apply by November 1, 2019. Please email Dr. Li for any questions. The University of Colorado is an Equal Opportunity/Affirmative Action Employer.

Learn about the lab: https://jingchunli.weebly.com/