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Articles published in professional journals written as a result of Sea Grant sponsored projects

These reprints are articles published in professional and academic journals written as a result of Sea Grant sponsored projects.


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A Multi-element Sediment Record of Hydrological and Environmental Changes From Lake Erie since 1800

OHSU-RS-1575
ABSTRACT:

Concentrations of aluminum, arsenic, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, potassium, selenium, sodium, tin, titanium, vanadium, and zinc were measured in a surface sediment core from the Sandusky basin of Lake Erie to detail the history of hydrological and environmental changes back to 1800. The results from hierarchical cluster and principal component analyses revealed four elemental groups. All the trace elements clustering with aluminum, iron, and manganese in Group I were enriched due to increased inputs from anthropogenic sources. The two conservative elements sodium and potassium clustering in Group II showed patterns of changes like those of water-level fluctuations. The two carbonate elements calcium and magnesium clustering in Group III showed intriguing but complex carbonate biogeochemistry associated with biogenic production, organic acid-induced dissolution and dilution by organic and aluminosilicate materials. The terrigenous element titanium in Group IV experienced two stages of depletion from increased organic fluxes in the 1820s and 1950s. Following the enactments of stringent regulations in the early 1970s, many of these elemental inputs have reduced considerably. But the concurrent reductions in the Sandusky basin were much slower than previously thought. Large increases in inputs from local storages (internal loading) were required to account for the slow reductions. The increased internal loading was caused by augmented organic materials from accelerated eutrophication which facilitated the transfer, transport, and cycling of many trace metals. This work has implications in ongoing research efforts to tackle the eutrophication problem because the complex ecosystem including the internal loading has changed considerably over the past two centuries.

DOI: 10.1007/s10933-017-9953-3 VOLUME: 58 ISSUE: 1 LENGTH: 19 pages
Reprint

A Decline in Benthic Algal Production May Explain Recent Hypoxic Events in Lake Erie's Central Basin

OHSU-RS-1574
ABSTRACT:

Since the late 1990s, the central basin of Lake Erie has reputedly experienced an increase in the frequency and severity of hypoxic events. However, total phosphorus (TP) loading, in-lake TP concentrations, chlorophyll a (Chl a), and sediment oxygen demand (SOD) have all declined in the central basin since the 1970s. Water clarity in this basin has declined from the 1970s to 2000s despite the invasion of dreissenid mussels around 1990. In shallow lakes, declines in benthic primary production (PP) can generate positive feedback loops between the internal loading of nutrients/dissolved organic carbon and hypoxic/anoxic conditions in the water column. Such a hypoxia-inducing mechanism driven by declines in benthic PP has not been explored in Lake Erie. To test if a decline in benthic PP might explain hypoxic events in the central basin of Lake Erie, we calculated the inter-decadal changes in benthic and planktonic algal production in this basin from the 1970s to the 2000s. Primary production models using water column Chl a concentrations and light attenuation indicated that benthic PP represents roughly 10% of the basin’s total areal PP. However, our calculations show that benthic PP declined from approximately 540 to 200 g C/m2 y since the 1970s. We propose that a decline in benthic PP may have played a key mechanistic role in the transition from externally-induced hypoxia (i.e. watershed nutrient loading fueling phytoplankton production) in the 1970s and 80s to internally-induced hypoxia (sediment resuspension and internal loading) since the late 1990s.

DOI: 10.1016/j.jglr.2017.03.016 VOLUME: 43 ISSUE: 3 LENGTH: 5 pages
Reprint

Population Genetic Structure and Comparative Diversity of Smallmouth Bass Micropterus dolomieu: Congruent Patterns From Two Genomes

OHSU-RS-1559
ABSTRACT:

Genetic diversity and divergence patterns of smallmouth bass Micropterus dolomieu spawning groups are analysed across its northern native range with mtDNA cytochrome b gene sequences and eight unlinked nuclear DNA microsatellite loci. Results reveal high levels of genetic variability and significant differences in allelic representation among populations (mtDNA: mean ± s.e., HD = 0·50 ± 0·06, mean ± s.e., θST = 0·41 ± 0·02 and microsatellites: mean ± s.e. HO = 0·46 ± 0·03, mean ± s.e. θST = 0·25 ± 0·01). The distributions of 28 variant mtDNA haplotypes, which differ by an average of 3·94 nucleotides (range = 1–8), denote divergent representation among geographic areas. Microsatellite data support nine primary population groups, whose high self-assignment probabilities likewise display marked divergence. Genetic patterns demonstrate: (1) high genetic diversity in both genomes, (2) significant divergence among populations, probably resulting from natal site homing and low lifetime migration, (3) support for three post-glacial refugia that variously contributed to the current northern populations, which remain evident today despite waterway connectivity and (4) a weak yet significant genetic isolation by geographic distance pattern, indicating that other processes affect the differences among populations, such as territoriality and site fidelity.

DOI: 10.1111/jfb.13296 VOLUME: 90 ISSUE: 5 LENGTH: 22 pages
Reprint

Development of Flood Warning System and Flood Inundation Mapping Using Field Survey and LiDAR Data for the Grand River near the City of Painesville, Ohio

OHSU-RS-1569
ABSTRACT:

Flooding is one of the most frequent natural disasters across the world, which damages properties and may take the lives of people. Flood warning systems can play a significant role in minimizing those effects by helping to evacuate people from the probable affected areas during peak flash flood times. Therefore, a conceptual approach of an automated flood warning system is presented in this research to protect several houses, roads, and infrastructures along the Grand River, which are vulnerable to flooding during a 500 year return period flash flood. The Grand River is a tributary of Lake Erie, which lies in the Grand River watershed in the northeastern region of the United States and has a humid continental climate and receives lake-effect precipitation. The flood warning system for the Grand River was developed specifically during high flow conditions by calculating flood travel time and generating the inundation mapping for 12 different selected flood stages, which were approximately 2 to 500 years in recurrence interval, ranging from 10 ft. to 21 ft. at gage station 04212100, near the City of Painesville, OH. A Hydraulic Engineering Center-River Analysis System (HEC-RAS) was utilized for hydraulic modeling. Geospatial data required for HEC-RAS was obtained using a Digital Elevation Model (DEM) derived from Light Detection and Ranging (LiDAR) datasets, which were pre-processed and post-processed in HEC-GeoRAS to produce flood inundation maps. The flood travel time and flood inundation maps were generated by integrating LiDAR data with field verified survey results in order to provide the evacuation lead time needed for the people of probable affected areas, which is different from earlier studies. The generated inundation maps estimate the aerial extent of flooding along the Grand River corresponding to the various flood stages at the gage station near the City of Painesville and Harpersfield. The inundation maps were overlaid on digital orthographic maps to visualize its aerial extents, which can be uploaded online to provide a real-time inundation warning to the public when the flood occurs in the river.

DOI: 10.3390/hydrology4020024 VOLUME: 4 ISSUE: 2 LENGTH: 1 page
Reprint

Multiple Models Guide Strategies for Agricultural Nutrient Reductions

OHSU-RS-1558
ABSTRACT:

In response to degraded water quality, federal policy makers in the US and Canada called for a 40% reduction in phosphorus (P) loads to Lake Erie, and state and provincial policy makers in the Great Lakes region set a load-reduction target for the year 2025. Here, we configured five separate SWAT (US Department of Agriculture’s Soil and Water Assessment Tool) models to assess load reduction strategies for the agriculturally dominated Maumee River watershed, the largest P source contributing to toxic algal blooms in Lake Erie. Although several potential pathways may achieve the target loads, our results show that any successful pathway will require large-scale implementation of multiple practices. For example, one successful pathway involved targeting 50% of row cropland that has the highest P loss in the watershed with a combination of three practices: subsurface application of P fertilizers, planting cereal rye as a winter cover crop, and installing buffer strips. Achieving these levels of implementation will require local, state/provincial, and federal agencies to collaborate with the private sector to set shared implementation goals and to demand innovation
and honest assessments of water quality-related
programs, policies, and partnerships.

DOI: 10.1002/fee.1472 VOLUME: 15 ISSUE: 3 LENGTH: 6 pages
Reprint

Kinetics and Mechanism of Ultrasonic Activation of Persulfate: An in Situ EPR Spin Trapping Study

OHSU-RS-1572
ABSTRACT:

Ultrasound (US) was shown to activate persulfate (PS) providing an alternative activation method to base or heat as an in situ chemical oxidation (ISCO) method. The kinetics and mechanism of ultrasonic activation of PS were examined in aqueous solution using an in situ electron paramagnetic resonance (EPR) spin trapping technique and radical trapping with probe compounds. Using the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), hydroxyl radical (•OH) and sulfate radical anion (SO4•–) were measured from ultrasonic activation of persulfate (US-PS). The yield of •OH was up to 1 order of magnitude greater than that of SO4•–. The comparatively high •OH yield was attributed to the hydrolysis of SO4•– in the warm interfacial region of cavitation bubbles formed from US. Using steady-state approximations, the dissociation rate of PS in cavitating bubble systems was determined to be 3 orders of magnitude greater than control experiments without sonication at ambient temperature. From calculations of the interfacial volume surrounding cavitation bubbles and using the Arrhenius equation, an effective mean temperature of 340 K at the bubble–water interface was estimated. Comparative studies using the probe compounds tert-butyl alcohol and nitrobenzene verified the bubble–water interface as the location for PS activation by high temperature with •OH contributing a minor role in activating PS to SO4•–. The mechanisms unveiled in this study provide a basis for optimizing US-PS as an ISCO technology.

DOI: 10.1021/acs.est.6b05392 VOLUME: 51 ISSUE: 6 LENGTH: 7 pages
Reprint

De Novo Transcriptome Sequencing and Analysis of Male, Pseudo-male and Female Yellow Perch, Perca flavescens

OHSU-RS-1571
ABSTRACT:

Transcriptome sequencing could facilitate discovery of sex-biased genes, biological pathways and molecular markers, which could help clarify the molecular mechanism of sex determination and sexual dimorphism, and assist with selective breeding in aquaculture. Yellow perch has unique gonad system and sexual dimorphism and is an alternative model to study mechanism of sex determination, sexual dimorphism and sexual selection. In this study, we performed the de novo assembly of yellow perch gonads and muscle transcriptomes by high throughput Illumina sequencing. A total of 212,180 contigs were obtained, ranging from 127 to 64,876 bp, and N50 of 1,066 bp. The assembly RNA-Seq contigs (≥200bp) were then used for subsequent analyses, including annotation, pathway analysis, and microsatellites discovery. No female- and pseudo-male-biased genes were involved in any pathways while male-biased genes were involved in 29 pathways, and neuroactive ligand receptor interaction and enzyme of trypsin (enzyme code, EC: 3.4.21.4) was highly involved. Pyruvate kinase (enzyme code, EC: 2.7.1.40), which plays important roles in cell proliferation, was highly expressed in muscles. In addition, a total of 183,939 SNPs, 11,286 InDels and 41,479 microsatellites were identified. This study is the first report on transcriptome information in Percids, and provides rich resources for conducting further studies on understanding the molecular basis of sex determinations, sexual dimorphism, and sexual selection in fish, and for population studies and marker-assisted selection in Percids.

DOI: 10.1371/journal.pone.0171187 VOLUME: 12 ISSUE: 2
Reprint

Microcystis Rising: Why Phosphorus Reduction Isn’t Enough to Stop CyanoHABs

OHSU-RS-1557
DOI: 10.1289 VOLUME: 125 ISSUE: 2 LENGTH: 5 pages
Reprint

Maternal Investment and Delayed Feeding in Neonatal Lake Erie Watersnakes: a Life-History Strategy

OHSU-RS-1565
ABSTRACT:

Neonatal growth can have lasting consequences on survival and reproduction. In many taxa, larger, faster growing neonates experience higher survival, reach sexual maturity more rapidly, and achieve higher lifetime fecundity. In contrast to their closest relatives, Lake Erie watersnakes grow slower, mature later, and may delay feeding until after their first hibernation. To determine if Lake Erie watersnakes do indeed delay feeding until after their first hibernation, we compared age class 0 (between birth and first hibernation) and age class 1 (emergence from hibernation and through the first full season) snakes in the field and in the laboratory. In the field, only 0.6% of pre-hibernation neonates were found to contain prey, while 11.9% of post-hibernation neonates contained prey. During captive feeding experiments, the probability of eating was positively correlated with age (binary logistic regression, Wald math formula = 25.354, P < 0.001). To clarify the underlying mechanism for delayed feeding, we compared neonatal yolk and fat reserves among species with delayed feeding (Lake Erie watersnakes, Graham’s crayfish-eating snakes), species that commence feeding immediately after birth (common gartersnakes, Dekay’s brown snakes) and a species falling between these extremes (queen snakes). Like Lake Erie watersnakes, Graham’s crayfish-eating snakes contained large energy reserves (yolk + fat body mass to carcass mass ratio = 0.39 and 0.24, respectively), common gartersnakes and Dekay’s brown snakes lacked measurable reserves (0.00), and queen snakes contained intermediate reserves (0.17). Taken together, this evidence suggests that neonatal Lake Erie watersnakes do delay feeding until after their first hibernation and contain large energy reserves at birth to facilitate this behavior. While most snake life-history studies have focused on the trade-off between offspring size and number, Lake Erie watersnake females invest large amounts of energy in offspring condition.

DOI: 10.1111/jzo.12404 VOLUME: 301 ISSUE: 2 LENGTH: 6 pages
Reprint

Fertilizer Placement and Application Timing as Strategies to Reduce Phosphorus Loading to Lake Erie

OHSU-RS-1564
ABSTRACT:

To reduce the intensity and frequency of harmful algal blooms in western Lake Erie, it has been recommended to reduce the phosphorus load, contributed by the Maumee River watershed (MRW) in northwest Ohio. As the largest contributor of phosphorus to Lake Erie, the dominantly agricultural MRW in northwest Ohio has been recommended to reduce phosphorus loads by 40%. To achieve such reductions, three agricultural nutrient management practices, (1) fertilizer placement within the soil, (2) adjusted seasonal timing of fertilizer application, and (3) adjusted date of fertilizer application to drier days have been recommended. To determine the potential phosphorus load reduction from implementing these three management practices, a SWAT model of the MRW was developed to evaluate the effectiveness of each practice for reducing SRP and total phosphorus (TP) load to the lake. Management scenarios were modeled with variations of the three practices from 2007 to 2012, and compared to historical data. Overall, maximum fertilizer placement had the greatest potential to influence SRP and TP loads; reducing spring SRP and TP loading by 42% and 27%, respectively compared to baseline levels. Seasonal fertilizer application timing also impacted spring SRP and TP loads, but to a lesser degree. Changing the date of application from wetter days to drier days across the watershed did not significantly affect SRP or TP loads, but this result is likely due to limitations of the SWAT simulation. These results indicate that maximizing fertilizer placement has a great potential to reduce TP and SRP runoff from the MRW.

DOI: 10.1016/j.jglr.2016.07.002 VOLUME: 42 ISSUE: 6 LENGTH: 7 pages
Reprint

What Motivates Farmers to Apply Phosphorus at the “Right” Time? Survey Evidence from the Western Lake Erie Basin

OHSU-RS-1563
ABSTRACT:

Phosphorus loadings from the Maumee River watershed have significantly compromised the Lake Erie ecosystem, as evidenced by the most severe harmful algal bloom in Lake Erie in 2015 and the shut-down of Toledo drinking water supply in 2014. Despite government payments for adoption of voluntary conservation practices, excess nutrient runoff from agricultural production remains a substantial challenge. The right timing of nutrient application is a critical best management practice (BMP). Using a unique survey of 2540 farmer respondents in the Maumee River watershed, this paper analyzes how socio-psychological, socio-demographic, and field-based spatial characteristics impact farmers’ adoption of timing-related best practices for nutrient management, including delaying broadcast application before a storm event, avoiding winter application of nutrients, and avoiding fall application of nutrients. Results reveal three unique classes of farmers for each of the timing-related management decisions. While the significance of most farmer and field characteristics varies across the three BMP adoption decisions, perceived efficacy—the belief that the particular practice will actually reduce dissolved phosphorus runoff from farm fields—is positively correlated with a higher likelihood of adopting each of the BMPs across almost all classes of farmers. For example, results from the ordered logit model suggest that a 20% increase in perceived efficacy would result in the likelihood of actual adoption of delaying broadcast from 35% to 48%. An implication is that policies and outreach efforts aimed at increasing farmers’ perceived efficacy of practices could lead to higher adoption levels, but the effectiveness may vary across different classes of farmers.

DOI: 10.1016/j.jglr.2016.08.007 VOLUME: 42 ISSUE: 6 LENGTH: 13 pages
Reprint

Anticipated Impacts of Climate Change on 21st Century Maumee River Discharge and Nutrient Loads

OHSU-RS-1562
ABSTRACT:

Climate change holds great potential to affect the Lake Erie ecosystem by altering the timing and magnitude of precipitation driven river discharge and nutrient runoff in its highly agricultural watershed. Using the SWAT hydrologic model and an ensemble of global climate models, we predicted Maumee River (Ohio) discharge during the 21st century under two Intergovernmental Panel on Climate Change (IPCC) greenhouse gas emissions scenarios: RCP4.5 (mid-range, moderate reductions) and RCP8.5 (high, “business as usual”). Annual discharge was projected to increase under both scenarios, both in the near-century (RCP4.5 = 6.5%; RCP8.5 = 2.0%) and late-century (RCP4.5 = 9.2%; RCP8.5 = 15.9%), owing to increased precipitation and reduced plant stomatal conductance. Holding fertilizer application rates at baseline levels, we found that reduced winter surface runoff and increased plant phosphorus (P) uptake led to a respective decrease in annual total P (TP) runoff in the near-century (RCP4.5 = − 4.3%; RCP8.5 = − 6.6%) and by the late-century (RCP4.5 = − 14.6%; RCP8.5 = − 7.8%). Likewise, soluble reactive P (SRP) runoff was predicted to decrease under both scenarios in the near-century (RCP4.5 = − 0.5%; RCP8.5 = − 3.5%) and by the late-century (RCP4.5 = − 11.8%; RCP8.5 = − 8.6%). By contrast, when fertilizer application was modeled to increase at the same rate as plant P uptake, TP loading increased 4.0% (0.9%) in the near-century and 9.9% (24.6%) by the late-century and SRP loading increased 10.5% (6.1%) in the near-century and 26.7% (42.0%) by the late-century under RCP4.5 (RCP8.5). Our findings suggest that changes in agricultural practices (e.g., fertilization rates) will be key determinants of Maumee River discharge during the 21st century.

DOI: 10.1016/j.jglr.2016.08.008 VOLUME: 42 ISSUE: 6 LENGTH: 10 pages
Reprint

Quantifying Emissions of Methane Derived From Anaerobic Organic Matter Respiration and Natural Gas Extraction in Lake Erie

OHSU-RS-1550
ABSTRACT:

Despite a growing awareness of the importance of inland waters in regional and global carbon © cycles, particularly as sources of the greenhouse gases carbon dioxide (CO2) and methane (CH4), very little is known about C sources and fluxes in the Laurentian Great Lakes, Earth’s largest surface freshwater system. Here, we present a study of CH4 dynamics in Lake Erie, which has large spring algae blooms linked to fertilizer runoff and followed by hypoxia, as well as an extensive network of natural gas wells and pipelines in Canadian waters. Lake Erie is a positive source of CH4 to the atmosphere in late summer, even in shallow regions without water column hypoxia. Stable isotopic measurements indicate that both biogenic and thermogenic CH4 contribute to emissions from Lake Erie. We estimate that Lake Erie emits 1.360.6 3 105 kg CH4-C d21 in late summer, with approximately 30% of CH4 derived from natural gas infrastructure. Additional work is needed to determine the spatial and temporal dynamics of CH4 emissions from Lake Erie and to confirm estimates of source contribution. Studies of the C cycle in large lakes are not as straightforward as those in smaller lakes, as, in addition to O2 availability, subsurface currents and high winds may exert significant control over dissolved CH4 patterns. If climate warming and increasing precipitation intensity lead to increased algal biomass and/or greater extent and duration of hypoxia, this may increase emissions of CH4 from Lake Erie in a positive feedback to climate change.

DOI: 10.1002/lno.10273 VOLUME: 61 ISSUE: 1 LENGTH: 10 pages
Reprint

Adaptations to Photoautotrophy Associated with Seasonal Ice Cover in a Large Lake Revealed by Metatranscriptome Analysis of a Winter Diatom Bloom

OHSU-RS-1568
ABSTRACT:

There is growing recognition that winter is an important season for growth of photoautotrophs in ice-covered freshwater environments. Exemplifying this are expansive under-ice blooms of filamentous diatoms in Lake Erie. Here we describe a metatranscriptome constructed from a phytoplankton community dominated by filamentous diatoms. As expected, a high percentage (> 73%) of the sequences with BLAST hits to nucleotides or proteins in National Center for Biotechnology Information databases were associated with photosynthetic algae of which the majority were diatoms, mainly Aulacoseira spp. and Stephanodiscus spp. which was confirmed by analysis of 18S rRNA gene transcripts and microscopy. Consistent with the winter growth environment, psychrophilic and low-light adaptations were observed. Prominent among adaptations to cold were transcripts for genes involved in biosynthesis of unsaturated fatty acids, which were consistent with expected increased membrane fluidity at low temperatures. Reflecting the combined effect of low winter insolation and high light attenuation were an abundant complement of reads for light-harvesting antennae, mainly genes encoding fucoxanthin chlorophyll a/c proteins. The presence of virulence factors originating from oomycetes offers support for new hypotheses into the eventual decline of Lake Erie’s winter diatom bloom. Whereas fungi were identified both through the metatranscriptome and by microscopy, dsRNA viruses of fungi were detected that may indirectly counter against fungal infection. This study demonstrates the utility of an environmental omics approach to yield insights underlying phototrophic life as well as the interactions of the entire microbial community in an extreme environment.

DOI: 10.1016/j.jglr.2016.07.025 VOLUME: 42 ISSUE: 5 LENGTH: 8 pages
Reprint

It Takes Two to Tango: When and Where Dual Nutrient (N & P) Reductions Are Needed to Protect Lakes and Downstream Ecosystems

OHSU-RS-1573
ABSTRACT:

Preventing harmful algal blooms (HABs) is needed to protect lakes and downstream ecosystems. Traditionally, reducing phosphorus (P) inputs was the prescribed solution for lakes, based on the assumption that P universally limits HAB formation. Reduction of P inputs has decreased HABs in many lakes, but was not successful in others. Thus, the “P-only” paradigm is overgeneralized. Whole-lake experiments indicate that HABs are often stimulated more by combined P and nitrogen (N) enrichment rather than N or P alone, indicating that the dynamics of both nutrients are important for HAB control. The changing paradigm from P-only to consideration of dual nutrient control is supported by studies indicating that (1) biological N fixation cannot always meet lake ecosystem N needs, and (2) that anthropogenic N and P loading has increased dramatically in recent decades. Sediment P accumulation supports long-term internal loading, while N may escape via denitrification, leading to perpetual N deficits. Hence, controlling both N and P inputs will help control HABs in some lakes and also reduce N export to downstream N-sensitive ecosystems. Managers should consider whether balanced control of N and P will most effectively reduce HABs along the freshwater-marine continuum.

DOI: 10.1021/acs.est.6b02575 VOLUME: 50 ISSUE: 20 LENGTH: 8 pages
Reprint

A Comparison of Water Sampling and Analytical Methods in Western Lake Erie

OHSU-RS-1554
Reprint

Leptodora kindtii Population Dynamics in the Island Region of Western Lake Erie Before and After the Invasion of the Predacious Cladoceran Bythotrephes Longimanus

OHSU-RS-1556
ABSTRACT:

Competition among native and non-native species can cause decreases in population size and production of both species. The native predaceous crustacean zooplankter Leptodora kindtii shares a similar niche with the invasive Bythotrephes longimanus in Lake Erie. This niche overlap may contribute to the decline in abundance, and production of L. kindtii in the Western Basin of Lake Erie. Historical (1946) and recent (2006) data were used to determine if the decline in L. kindtii abundance and production was associated with the effects of B. longimanus, which invaded Lake Erie in the mid-1980’s. Pre-invasion abundances and lengths of L. kindtii were compared with current data (2006). A change in prey community abundance, composition and dynamics were observed, relative to pre-invasion, with a marked decline in abundance and size of L. kindtii after the invasion of B. longimanus. Competition for food and direct predation are two explanations, among others, for the declines observed in L. kindtii size, abundance and production that have occurred since B. longimanus invasion.

VOLUME: 116 ISSUE: 2 LENGTH: 7 pages
Reprint

Two Decades of Genetic Consistency in a Reproductive Population in the Face of Exploitation: Patterns of Adult and Larval Walleye (Sander vitreus) from Lake Erie’s Maumee River

OHSU-RS-1555
ABSTRACT:

Analyses of genetic variability and allelic composition in a species exhibiting reproductive fidelity to natal sites may provide important ecological indication of temporal population dynamics, facilitating understanding responses to past disturbances and future climate change. The walleye is an ecologically and economically valuable species, whose largest fishery centers in Lake Erie of the Laurentian Great Lakes; it exhibits reproductive site fidelity, despite otherwise wide-ranging dispersal. We tested whether genetic composition and diversity have remained temporally stable in Lake Erie’s Maumee River, which is the largest and most highly fished spawning run. This population has experienced over a century of exploitation, habitat alterations, and pollution, which may have affected genetic structure and might influence future sustainability. Fourteen nuclear DNA microsatellite loci were analyzed from 744 spawning run walleye to test genetic patterns across: (1) years (N = 12, spanning 1995–2013), (2) birth year cohorts, (3) the sexes, (4) those reproducing earlier (ages 2–6) versus later (7 or older) in life, and (5) the adults versus larvae. Results indicated stability in genetic diversity levels (mean HO = 0.76 ± 0.03) and allelic composition across years (FST = 0.000–0.006, NS), cohorts (FST = 0.000–0.013, NS), sexes (FST = 0.000, NS), earlier versus later reproduction (FST = 0.000, NS), and between the larvae and adults (FST = 0.000–0.004, NS). Number of breeders and effective population size were substantial and consistent. This reproductive population thus has maintained genetic stability and high diversity, despite intensive anthropogenic pressures.

DOI: 10.1007/s10592-016-0866-x ISBN: 1566-0621 VOLUME: 17 ISSUE: 6 LENGTH: 17 pages
Reprint

Combining COMSOL Modeling with Acoustic Pressure Maps to Design Sono-Reactors

OHSU-RS-1526
ABSTRACT:

Scaled-up and economically viable sonochemical systems are critical for increased use of ultrasound in environmental and chemical processing applications. In this study, computational simulations and acoustic
pressure maps were used to design a larger-scale sono-reactor containing a multi-stepped ultrasonic horn. Simulations in COMSOL Multiphysics showed ultrasonic waves emitted from the horn neck and tip, generating multiple regions of high acoustic pressure. The volume of these regions surrounding the horn neck were larger compared with those below the horn tip. The simulated acoustic field was verified by acoustic pressure contour maps generated from hydrophone measurements in a plexiglass box filled with water. These acoustic pressure contour maps revealed an asymmetric and discrete distribution of acoustic pressure due to acoustic cavitation, wave interaction, and water movement by ultrasonic irradiation.

The acoustic pressure contour maps were consistent with simulation results in terms of the effective scale of cavitation zones (10 cm and <5 cm above and below horn tip, respectively). With the mapped acoustic field and identified cavitation location, a cylindrically-shaped sono-reactor with a conical bottom was designed to evaluate the treatment capacity (5 L) for the multi-stepped horn using COMSOL simulations. In this study, verification of simulation results with experiments demonstrates that coupling of COMSOL simulations with hydrophone measurements is a simple, effective and reliable scientific method to evaluate reactor designs of ultrasonic systems.

DOI: 10.1016/j.ultsonch.2016.01.036 VOLUME: 31 LENGTH: 8 pages
Reprint

Feeding Glycyrrhiza glabra (liquorice) and Astragalus membranaceus (AM) Alters Innate Immune and Physiological Responses in Yellow Perch (Perca flavescens)

OHSU-RS-1570
ABSTRACT:

The current work assessed the potential immunomodulatory and growth-promoting effects of Astragalus membranaceus (AM) and Glycyrrhiza glabra (liquorice) in Yellow perch (Perca flavescens). In this regard, fish with an average weight of 31 ± 1.0 g were divided into five groups, and fed daily with an additive-free basal diet (control); 1, 2, and 3% (w/w) Glycyrrhiza glabra, and the fifth diet was incorporated with a combination of 1% G. glabra-AM for a four-week period. Immunological, biochemical and growth parameters were measured; and sub-groups of fish were exposed to 1-week starvation. The results showed that incorporating AM and liquorice in the diet significantly improved Immunological [superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), Lipid peroxidase (LPx) and lysozyme activities], biochemical [Aspartate Aminotransferase (AST) and Alanine Transaminase (ALT) activities; and glucose and cortisol concentrations] and growth performance parameters [body mass gain (BMG), specific growth rate (SGR), length, condition factor (K) and feed conversion ratio (FCR)]. In addition, markedly up-regulated the expression of related genes [Insulin-Like Growth Factor-1 (IGF-1), Serum amyloid A (SAA), Complement Component C3 (CCC3), Alpha 2 Macroglobulin (A2M), SOD and GPx] in treated fish groups compared to the control. Conclusively, feeding AM and liquorice diets significantly increased (P < 0.05) growth performance, antioxidant and immune response profiles throughout the entire experiment, suggesting their beneficial rule as natural anti-stress agents.

DOI: 10.1016/j.fsi.2016.04.024 VOLUME: 54 LENGTH: 10 pages
Reprint

Ice Cover Extent Drives Phytoplankton and Bacterial Community Structure in a Large North-temperate Lake: Implications For a Warming Climate

OHSU-RS-1567
ABSTRACT:

Mid-winter limnological surveys of Lake Erie captured extremes in ice extent ranging from expansive ice cover in 2010 and 2011 to nearly ice-free waters in 2012. Consistent with a warming climate, ice cover on the Great Lakes is in decline, thus the ice-free condition encountered may foreshadow the lakes future winter state. Here, we show that pronounced changes in annual ice cover are accompanied by equally important shifts in phytoplankton and bacterial community structure. Expansive ice cover supported phytoplankton blooms of filamentous diatoms. By comparison, ice free conditions promoted the growth of smaller sized cells that attained lower total biomass. We propose that isothermal mixing and elevated turbidity in the absence of ice cover resulted in light limitation of the phytoplankton during winter. Additional insights into microbial community dynamics were gleaned from short 16S rRNA tag (Itag) Illumina sequencing. UniFrac analysis of Itag sequences showed clear separation of microbial communities related to presence or absence of ice cover. Whereas the ecological implications of the changing bacterial community are unclear at this time, it is likely that the observed shift from a phytoplankton community dominated by filamentous diatoms to smaller cells will have far reaching ecosystem effects including food web disruptions.

DOI: 10.1111/1462-2920.12819 VOLUME: 18 ISSUE: 6 LENGTH: 15 pages
Reprint

Nutrient-Controlled Niche Differentiation of Western Lake Erie Cyanobacterial Populations Revealed via Metatranscriptomic Surveys

OHSU-RS-1532
ABSTRACT:

Although toxic cyanobacterial blooms in western Lake Erie threaten drinking water supplies and are promoted by nutrient loading, the precise nutrient regime that selects specific cyanobacteria populations is poorly understood. Here, we assess shifts in cyanobacterial abundances and global gene-expression patterns in response to natural and manipulated gradients in nitrogen and phosphorus to identify gene pathways that facilitate dominance by different cyanobacteria. Gradients in soluble reactive phosphorus shaped cyanobacterial communities and elicited the largest transcriptomic responses. Under high-P conditions (closest to the mouth of the Maumee River), Anabaena and Planktothrix were the dominant cyanobacterial populations, and experimental P and ammonium enrichment promoted nitrogen fixation gene (nifH) expression in Anabaena. For Microcystis, experimental additions of P up-regulated genes involved in phage defense, genomic rearrangement, and nitrogen acquisition but led to lower abundances. Within offshore, low-P regions of the western basin of Lake Erie, Microcystis up-regulated genes associated with P scavenging (pstSCAB, phoX) and dominated cyanobacterial communities. Experimental additions of ammonium and urea did not alter Microcystis abundances but did up-regulate protease inhibitors (aer and mcn gene sets) and microcystin synthetase genes (mcy), with urea enrichment yielding significant increases in microcystin concentrations. Our findings suggest that management plans that reduce P loads alone may not significantly reduce the risk of cyanobacterial blooms in western Lake Erie but rather may promote a shift among cyanobacterial populations (Microcystis, Anabaena, and Planktothrix) toward a greater dominance by toxic strains of Microcystis.

DOI: 10.1021/acs.est.5b03931 VOLUME: 50 ISSUE: 2 LENGTH: 11 pages
Reprint

Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size

OHSU-RS-1524
DOI: 10.5061/dryad.fk71c VOLUME: 11 ISSUE: 1 LENGTH: 15 pages
Reprint

Quantifying and Reducing Uncertainty in Estimated Microcystin Concentrations from the ELISA Method

OHSU-RS-1531
DOI: 10.1021/acs.est.5b03029 VOLUME: 49
Reprint

Designing and Characterizing a Multi-Stepped Ultrasonic Horn for Enhanced Sonochemical Performance

OHSU-RS-1527
ABSTRACT:

The commonly used ultrasonic horn generates localized cavitation below its converging tip resulting in a dense bubble cloud near the tip and limiting diffusion of reactive components into the bubble cloud or reactive radicals out of the bubble cloud. To improve contact between reactive components, a novel ultrasonic horn design was developed based on the principles of the dynamic wave equation. The horn, driven at 20 kHz, has a multi-stepped design with a cone-shaped tip increasing the energy-emitting surface areas and creating multiple reactive zones. Through different physical and chemical experiments, performance of the horn was compared to a typical horn driven at 20 kHz. Hydrophone measurements showed high acoustic pressure areas around the horn neck and tip. Sonochemiluminescence experiments verified multiple cavitation zones consistent with hydrophone readings. Calorimetry and dosimetry results demonstrated a higher energy efficiency (31.3%) and a larger hydroxyl radical formation rate constant (0.36 μM min−1) compared to typical horns. In addition, the new horn degraded naphthalene faster than the typical horn tested. The characterization results demonstrate that the multi-stepped horn configuration has the potential to improve the performance of ultrasound as an advanced oxidation technology by increasing the cavitation zone in the solution.

DOI: 10.1016/j.ultsonch.2015.05.013 VOLUME: 27 LENGTH: 8 pages
Reprint

Short Winters Threaten Temperate Fish Populations

OHSU-RS-1519
ABSTRACT:

Although climate warming is expected to benefit temperate ectotherms by lengthening the summer growing season, declines in reproductive success following short, warm winters may counter such positive effects. Here we present long-term (1973–2010) field patterns for Lake Erie yellow perch,Perca flavescens, which show that failed annual recruitment events followed short, warm winters. Subsequent laboratory experimentation and field investigations revealed how reduced reproductive success following short, warm winters underlie these observed field patterns. Following short winters, females spawn at warmer temperatures and produce smaller eggs that both hatch at lower rates and produce smaller larvae than females exposed to long winters. Our research suggests that continued climate warming can lead to unanticipated, negative effects on temperate fish populations.

DOI: 10.1038/ncomms8724 VOLUME: 6 LENGTH: 9 pages
Reprint

The Great Lakes Charter Fishing Industry: 2002 to 2011

OHSU-RS-1518
DOI: 10.1080/03632415.2015.1029574 VOLUME: 40 ISSUE: 5
Reprint

Effects of Increasing Nitrogen and Phosphorus Concentrations on Phytoplankton Community Growth and Toxicity During Planktothrix Blooms in Sandusky Bay, Lake Erie

OHSU-RS-1530
ABSTRACT:

Sandusky Bay experiences annual toxic cyanobacterial blooms dominated by Planktothrix agardhii/suspensa. To further understand the environmental drivers of these events, we evaluated changes in the growth response and toxicity of the Planktothrix-dominated blooms to nutrient amendments with orthophosphate (PO4) and inorganic and organic forms of dissolved nitrogen (N; ammonium (NH4), nitrate (NO3) and urea) over the bloom season (June – October). We complemented these with a metagenomic analysis of the planktonic microbial community. Our results showed that bloom growth and microcystin (MC) concentrations responded more frequently to additions of dissolved N than PO4, and that the dual addition of NH4 + PO4 and Urea + PO4 yielded the highest MC concentrations in 54% of experiments. Metagenomic analysis confirmed that P. agardhii/suspensa was the primary MC producer. The phylogenetic distribution of nifH revealed that both heterocystous cyanobacteria and heterotrophic proteobacteria had the genetic potential for N2 fixation in Sandusky Bay. These results suggest that as best management practices are developed for P reductions in Sandusky Bay, managers must be aware of the negative implications of not managing N loading into this system as N may significantly impact cyanobacterial bloom size and toxicity.

DOI: 10.1021/acs.est.5b00799 VOLUME: 49 ISSUE: 12 LENGTH: 10 pages
Reprint

An examination of sources of sensitivity of consumer surplus estimates in travel cost models

OHSU-RS-1514
ABSTRACT:

We examine sensitivity of estimates of recreation demand using the Travel Cost Method (TCM) to four factors. Three of the four have been routinely and widely discussed in the TCM literature: a) Poisson verses negative binomial regression; b) application of Englin correction to account for endogenous
stratification; c) truncation of the data set to eliminate outliers. A fourth issue we address has not been widely modeled: the potential effect on recreation demand of the interaction between income and travel cost. We provide a straightforward comparison of all four factors, analyzing the impact of each on regression parameters and consumer surplus estimates. Truncation has a modest effect on estimates
obtained from the Poisson models but a radical effect on the estimates obtained by way of the negative binomial. Inclusion of an income-travel cost interaction term generally produces a more conservative but not a statistically significantly different estimate of consumer surplus in both Poisson and negative binomial models. It also generates broader confidence intervals. Application of truncation, the Englin
correction and the income-travel cost interaction produced the most conservative estimates of consumer surplus and eliminated the statistical difference between the Poisson and the negative binomial. Use of the income-travel cost interaction term reveals that for visitors who face relatively low travel costs, the relationship between income and travel demand is negative, while it is positive for those who face high travel costs. This provides an explanation of the ambiguities on the findings regarding the role of income
widely observed in the TCM literature. Our results suggest that policies that reduce access to publicly owned resources inordinately impact local low income recreationists and are contrary to environmental justice.

Reprint

Length-weight Relationships of the Emerald Shiner (Notropis atherinoides - Rafinesque, 1818) in the Western Basin of Lake Erie

OHSU-RS-1504
DOI: na ISBN: na VOLUME: 114 ISSUE: 2 LENGTH: 9 pages
Reprint

Age and Growth of Round Goby Neogobius Melanostomus Associated with Depth and Habitat in the Western Basin of Lake Erie

OHSU-RS-1525

Poor condition may indicate that the Lake Erie population has reached saturation or may reflect indirect fitness costs associated with increasing anoxic or hypoxic hypolimnion conditions.

ABSTRACT:

Round goby Neogobius melanostomus were examined from the Bass Islands area in the western basin of Lake Erie, U.S.A., to determine age and growth correlations. A total of 188 specimens were collected and examined during summer 2011 with 90 aged using scale analysis. Fish were grouped by sex, depth of habitat and habitat type (anthropogenically modified shallows, natural shallows and open lake deep water). Fish ranged from 17 to 117 mm total length (LT ) and 0+ to 3+ years. Males dominated the population (1·94:1) and backcalculated age showed that both sexes grew exponentially, with male growth rate increasing faster than female. Males were significantly larger than females in LT and mass (both P < 0·001). The relative mass index (Wr ) was low for the sampled population (mean ± s.d. = 32·00 ± 26·87 g), implying that the health of the Bass Island area population is very poor when compared with the species throughout its range. This could be due to a lack of food resources related to population size or that the fish is not optimally utilizing the available food resources. In contradiction to these findings, regression slope coefficient (b), calculated using Fulton’s condition factor (K) (mean ± s.d. =1·50 ± 0·20), was very low for each habitat, implying a healthy population throughout. This seemingly opposite effect may be due to more individuals per unit area in shallow waters, which would cause increased competition for resources. Poor condition may indicate that the Lake Erie population has reached saturation or may reflect indirect fitness costs associated with increasing anoxic or hypoxic hypolimnion conditions.

DOI: 10.1111/jfb.12576 VOLUME: 86 ISSUE: 2 LENGTH: 16 pages
Reprint

Temporal Population Genetic Structure of Yellow Perch Spawning Groups in the Lower Great Lakes

OHSU-RS-1515
ABSTRACT:

This study tested the hypothesis that the genetic composition of Yellow Perch Perca flavescens spawning groups at specific sites remained consistent among years or age-cohorts; this likely would influence spatial population structure and be important for delineating management units. Previous studies identified that spawning groups genetically differed among locations across fine geographic scales, but it was unknown whether these patterns persisted from year to year. We analyzed 15 nuclear DNA microsatellite loci from Yellow Perch spawning at six Lake Erie locations in 2009 in reference to two out-groups spawning in Lakes St. Clair and Ontario. Results were compared with a prior study of samples from the same locations that had been collected in various years, ranging from 2001 to 2005. We evaluated consistency for two of the spawning groups across multiple birth-year-cohorts. Results indicated that the levels of genetic diversity were similar across all spawning groups and years. All eight spawning groups genetically differed from one other, with their allelic compositions varying between the two sampling periods. Some variation occurred among individual sampling years and birth-cohorts, with the 2003 cohort being the most distinctive. Sampling groups contained relatively high proportions of full siblings (mean = 18.5%, ranging to 75% for the 2001 birth-cohort spawning at the eastern Lake Erie site), yet inbreeding appeared relatively low. Differences at sampling sites over time did not appear to reflect genetic drift but may instead suggest that spawning groups reproduce in slightly different locations from year to year or perhaps within a given season; this merits examination. Spatial and temporal patterns may reflect kin-group structuring and differential reproductive success, in which strong year-classes dominate spawning groups and impact genetic structure.

DOI: 10.1080/00028487.2014.982260 VOLUME: 144 ISSUE: 1
Reprint

Efficacy of formalin, iodine and sodium chloride in improvement of egg hatching rate and fry survival prior to the onset of exogenous feeding in yellow perch

OHSU-RS-1508
DOI: 10.1111/are.12694 LENGTH: 9 pages
Reprint

Taxonomy, Distribution, and Evolution of the Percidae

OHSU-RS-1560
ABSTRACT:

The family Percidae exclusively is native to freshwaters of the Northern Hemisphere, with just two of its genera divided between Eurasia and North America. Percidae comprises 11 genera and an estimated 266–275 species, reaching tremendous species richness in the North American darters. We provide an up-to-date account relating the results of the latest DNA sequence and morphological analyses to resolve the relationships of the family Percidae, including its component genera and species. We provide newly assembled distribution maps for the taxa, and summarize their primary distinguishing morphological characters and life history. For each genus, the latest phylogenetic tree of species relationships is shown and explained. We relate these findings to historic biogeography and contemporary distributions. Just recently, tremendous inroads have been made using new molecular tools and analyses that allow us to begin to understand the tremendous evolutionary diversification of the Percidae, as well as the landscape and climate factors that have shaped these patterns. This information may provide an important indication of the future responses of percid taxa to continued anthropogenic influences.

DOI: 10.1007/978-94-017-7227-3_1 LENGTH: 57 pages
Reprint

Feeding Ecology of the Invasive Round Goby, Neogobius melanostomus (Pallas, 1814), Based on Laboratory Size Preference and Field Diet in Different Habitats in the Western Basin of Lake Erie

OHSU-RS-1523
VOLUME: 10 ISSUE: 4 LENGTH: 11 pages
Reprint

Occupancy, Activity, and Relationships to Watershed Factors in Predicting Burrowfidelity in the Digger Crayfish Fallicambarus Fodiens (Cottle, 1863)

OHSU-RS-1506
ABSTRACT:

An intensive single season pilot study was conducted with the digger crayfish, Fallicambarus fodiens (Cottle, 1863) to evaluate relationships between burrow and wetland attributes. Factor Analysis identified significant factors correlated with burrow placement, individual presence, type and frequency of activity. Factor 1 explained 36.89% of the variance associated with hydric type, percent soil moisture, fine substrate grain sizes, and habitat condition, while factor 2 explained 14.78% of the variance based on large grain particle sizes. A significant difference was observed in crayfish inhabitant activity with trap status, burrow state, and presence of activity. Four specific types of activities were related to distance to above groundwater including the trap being pulled into the burrow, the burying of the trap into a burrow cap, a capped burrow established beneath the trap, and relationship with standing water. Based on 12.5% individual recapture, 100% were present in the original burrow of capture.

DOI: 10.1163/1937240X-00002320 VOLUME: 35 ISSUE: 2 LENGTH: 8 pages
Reprint

Comparative Genetic Diversity, Population Structure, and Adaptations of Walleye and Yellow Perch Across North America

OHSU-RS-1561
ABSTRACT:

The yellow perch Perca flavescens and the walleye Sander vitreus are native North American percid fishes, which have considerable fishery and ecological importance across their wide geographic ranges. Over the past century, they were stocked into new habitats, often with relative disregard for conserving local genetic adaptations. This chapter focuses on their comparative population structure and genetic diversity in relationship to historical patterns, habitat connectivity, dispersal ability, distributional abundances, and reproductive behavior. Both species possess considerable genetic structure across their native ranges, exhibiting similar patterning of discontinuities among geographic regions. The two species significantly differ in levels of genetic diversity, with walleye populations possessing overall higher genetic variability than yellow perch. Genetic divergence patterns follow the opposite trend, with more pronounced differences occurring among closely spaced spawning aggregations of yellow perch than walleye. Results reveal broad-scale correspondence to isolation by geographic distance, however, their fine-scale population structures show less relationship, often with pronounced genetic differences among some nearby reproductive groups. Genetic composition of spawning groups is stable from year to year in walleye, according to two decades of data, and is less consistent in yellow perch. These patterns appear to reflect fundamental behavioral differences between the two species.

DOI: 10.1007/978-94-017-7227-3_25 LENGTH: 46 pages
Reprint

Evolutionary Relationships, Population Genetics, and Ecological and Genomic Adaptations of Perch (Perca)

OHSU-RS-1521
ABSTRACT:

The latest results about the evolutionary, biogeographic, and population genetic relationships of the three species comprising the percid fish genus Perca are presented, explained, and discussed. New analyses from new data dated the origin of the genus to an estimated 19.8 million years ago (mya) during the early Miocene Epoch, and the distribution of ancestral Perca likely extended across the North Atlantic Land Bridge until the mid-Miocene. The earliest evolutionary bifurcation led to the diversifi cation of the European perch P. fl uviatilis from the lineage shared by the common ancestor of the North American yellow perch P. fl avescens and the Eurasian Balkash perch P. schrenkii. The latter two species diverged during the later Miocene, after the Land Bridge was closed. The European and yellow perches are both widely distributed across their respective continents, with biogeographic areas housing high genetic distinctiveness. Population genetic structure in their northern regions were shaped by post-glacial colonization patterns from multiple refugia, whose admixture increased diversity. Today’s spawning groups are modest in genetic diversity yet very divergent from one another, which may reflect an apparent tendency of perch to live with relatives throughout their lives. There is a disconnect between the genetic divisions among populations and the delineation of fishery management units in the yellow perch, which is of concern. Employing a combined fisheries management and genetics/genomic approach will provide further understanding to help maintain the genetic diversity and unique adaptations of perch populations in the face of increasing anthropogenic influences, including climate change.

LENGTH: 39 pages
Reprint

A Comprehensive Approach to Evaluating Watershed Models for Predicting River Flow Regimes Critical to Downstream Ecosystem Services

OHSU-RS-1516
Reprint

Diet Shift Response in Round Goby, Neogobius melanostomus, Based on Size, Sex, Depth and Habitat in the Western Basin of Lake Erie

OHSU-RS-514
VOLUME: 30 ISSUE: 5 LENGTH: 7 pages
Reprint

Summer phytoplankton nutrient limitation in Maumee Bay of Lake Erie during high-flow and low-flow years

OHSU-RS-1503

Manuscript comparing Maumee Bay phytoplankton growth from 2010-2012

ABSTRACT:

Algal production inMaumee Bay in western Lake Erie is highly affected by inputs of nitrogen (N) and phosphorus (P) from the Maumee River, which drains predominantly agricultural lands, leading to the formation of cyanobacterial blooms. In a 3-year study, precipitation and discharge ranged from relatively low (2012) to relatively high (2011) with corresponding changes in the size of the cyanobacterial bloom. This study aimed to quantify the relation between river discharge and algal nutrient limitation in Maumee Bay. During the summer growing seasons, 20 nutrient enrichment bioassays were performed to determine which nutrient (P or N) might limit phytoplankton growth; and ambient N and P concentrations were monitored. The bioassays suggested that phytoplankton growth shifted from P-limited to N-limited during summer of the low and intermediate discharge years (2012 and 2010, respectively), whereas during the high discharge year (2011) phytoplankton were nutrient-replete before becoming N-limited. Phosphorus-replete growth during the high discharge year likely was due to high P loads from the river and dissolved P concentrations greater than 1 μmol/L. Symptoms of N-limited growth occurred during August and September in all three years and during July of 2012 when NO3 − plus NH4 + concentration was less than 7.29 μmol/L suggesting lowor no correspondence between N-limitation and size of the cyanobacterial bloom. Occurrence of a relatively small cyanobacterial bloom in 2012 following the record-breaking bloom in 2011 suggests the possibility of fast-reversal of eutrophication in Maumee Bay if P loading from the watershed could be decreased.

DOI: 10.1016/j.jglr.2014.04.009 VOLUME: 40 ISSUE: 3 LENGTH: 7 pages
Reprint

Connecting the blooms: tracking and establishing the origin of the record-breaking Lake Erie Microcystis bloom of 2011 using DGGE

OHSU-RS-1500
ABSTRACT:

Summer blooms of Microcystis now occur every year in Lake Erie with varying concentration, duration, and spatial extent. The recording-breaking bloom of 2011 began in the western corner of the lake during early summer, and reached its peak in late summer covering 2968 km2. Start and peak blooms were offset by 3 mo and separated by 120 km, raising the question: Is Microcystis transported across the lake or do separate blooms arise from separate source populations? This study addressed this question by measuring the genetic diversity of Microcystis across the lake and throughout the summer. Seven sites separated by about 100 km were sampled monthly during the summer of 2011 for genetic analysis of the Microcystis population. Furthermore, 2 major rivers (Maumee and Sandusky) and lake sediments were sampled and collected prior to bloom formation to investigate source populations. Denaturing gradient gel electrophoresis was used to generate Microcystis-specific molecular fingerprints of the 16S-23S rRNA internal transcribed spacer region. Dendrograms and principal component analysis were used to investigate similarity among samples. Fingerprints of lake water samples were more similar to the sediments than tributaries, indicating the sediments were a more likely bloom source. All lakes samples collected were > 50% similar with several universal bands, indicating Microcystis was transported west to east by water currents and that the beginning and peak blooms were not isolated.

This information characterizes the origin and movement of this massive and problematic bloom, and can be used to inform management practices aimed at preventing blooms in Lake Erie.

DOI: 10.3354/ame01708 VOLUME: 73 ISSUE: 73
Reprint

Massive outbreaks of Noctiluca scintillans blooms in the Arabian Sea due to spread of hypoxia

OHSU-RS-1510
Reprint

Interactive Effects of Temperature, Nitrogen, and Zooplankton on Growth and Protein and Carbohydrate Content of Cyanobacteria from Western Lake Erie

OHSU-RS-1517
ABSTRACT:

Harmful algal blooms (HABs) in freshwater ecosystems, especially of cyanobacterial species, are becoming more frequent and expanding geographically, including in Lake Erie in North America. HABs are the result of complex and synergistic environmental factors, though N or P eutrophication is a leading cause. With global mean temperatures expected to increase an additional 2˚C – 5˚C by 2100, cyanobacterial blooms are predicted to increase even more, given their typically-high temperature optimum for growth. We investigated how increases in temperature and nitrogen, singly or in combination, affect the growth, food quality, and herbivory of Lake Erie cyanobacteria. Algal community samples collected from Lake Erie, and isolated non-N-fixing (Microcystis aeruginosa) and N-fixing (Anabaena flos-aquae) cyanobacterial species, were cultured at 20˚C, 25˚C, or 30˚C, and at 5, 50, 150, or 250 μM N, and then analyzed for growth and (for isolates) content of total protein and non-structural carbohydrates (NSC). Temperature and N both affected algal growth, and there were temperature × N interactions, which were sometimes affected by presence/absence of zooplankton. For example, cyanobacteria (but not green algae) growth increased with both temperature and N, especially from 25˚C to 30˚C, but N and herbivore presence increased cyanobacterial growth primarily only at 30˚C. In general, temperature and N had little consistent effect on NSC, but increasing temperature and N tended to increase protein content in Microcystis and Anabaena (temperature effects mostly at higher N levels). In Anabaena, increases in N did not increase growth or protein at 20˚C or 25˚C, but did increase both at 30˚C, indicating that N fixation.

Reprint

Genetic History of Walleyes Spawning in Lake Erie's Cattaraugus Creek: a Comparison of Pre- and Poststocking

OHSU-RS-1522
ABSTRACT:

Fish stocking (artificial supplementation) has been used to augment populations and angling opportunities. However, genetic composition and adaptations of native fish populations may be affected, raising management concerns. From 1995 to 2000, the New York State Department of Environmental Conservation stocked Walleye Sander vitreus fry and fingerlings from the Maumee River (western Lake Erie) into Cattaraugus Creek (eastern Lake Erie). We analyzed nuclear microsatellite (sat) DNA and mitochondrial DNA (mtDNA) variation in Cattaraugus Creek Walleyes for comparisons between prestocking and poststocking groups, among annual spawning runs (1998–2011), among age cohorts, and between sexes. Results for genetic differentiation (index FST) were not significant between prestocking and poststocking groups (sat: FST = 0.003; mtDNA: FST < 0.001), and the two groups did not resemble stocked Maumee River fingerlings (sat: FST = 0.003–0.012; mtDNA: FST = 0.076–0.090). Tests for differentiation were not significant among annual spawning runs (sat: FST = <0.001–0.007; mtDNA: FST = <0.001–0.049), among age cohorts (sat: FST = <0.001–0.006; mtDNA: FST = <0.001–0.097), or between sexes (sat: FST < 0.001; mtDNA: FST < 0.001). Genetic diversity levels were high and consistent (sat: observed heterozygosity [mean ± SE] = 0.71 ± 0.04; mtDNA: haplotype diversity = 0.79 ± 0.01). Thus, despite stocking, the genetic signature of the native spawning run remained distinctive. However, the genetic composition of the local wild population and the stocking source should be assessed prior to any future supplementation plans.

DOI: 10.1080/00028487.2014.935477 VOLUME: 143 ISSUE: 5 LENGTH: 12 pages
Reprint

Intra-andinter-seasonalvariabilityofnutrientsinatropical monsoonal estuary(Zuari,India)

OHSU-RS-1512

A study was conducted to understand the intra- and inter-seasonal variability of dissolved oxygen and nutrients in a tropical monsoon estuary (Zuari in Goa, India). We adopted a dual sampling approach with (a) daily or alternate day sampling at a fixed location in the mid-estuarine zone and (b) longitudinal transect sampling from freshwater end to mouth during spring and neap tides of each month for about a year. Multivariate statistical analyses of oxygen and nutrients were carried out to evaluate the hypotheses: (i) biogeochemical processes chiefly regulate their variability and (ii) anthropogenic inputs lead to material accumulation in the estuary. Multivariate statistical analyses helped identify the controlling factors of the oxygen and nutrient variability. Our results significantly revealed (i) physical forcings (freshwater discharge and tidal circulation, these also facilitate sedimentary releases) are more important than biogeochemical processes in determining oxygen and nutrient variability in the water column and (ii) the monsoon driven regular annual flushing makes the system resilient to human interference as the Zuari estuary returns to normalcy by postmonsoon every year. Our study identified the significance of subsurface discharges in transporting mining effluents from the river basin. Results also suggest that extrapolation of controlling factors of biogeochemical variables at a fixed location to the entire estuary is untenable since the relative dominance of forcings vary in time and space in the estuary.

DOI: 10.1016/j.csr.2014.04.005 VOLUME: 82
Reprint

A population genetic window into the past and future of the walleye Sander vitreus: relation to historic walleye and the extinct “blue pike” S. v. “glaucus”

OHSU-RS-1511
DOI: 10.1186/1471-2148-14-133 VOLUME: 14
Reprint

Submersion Tolerance in a Lakeshore Population of Pardosa lapidicina (Araneae: Lycosidae)

OHSU-RS-1509
DOI: 10.1636/B13-44.1 VOLUME: 42 ISSUE: 2
Reprint

Oxygen use by Nitrification in the Hypolimnion and Sediments of Lake Erie

OHSU-RS-1540
ABSTRACT:

Nitrification is an oxygen consumptive process, consuming 2 mol of oxygen permol of ammonium oxidized. Hypolimnion
and sediment sampleswere collected during the summers of 2008–2010 in Lake Erie to determine the
total oxygen consumption and oxygen consumption fromnitrification by blocking nitrification with selective inhibitors.
Oxygen consumption by nitrification in the hypolimnion was 3.7 ± 2.9 (mean ± 1 SD) μmol O2/L/d,
with nitrification accounting for 32.6 ± 22.1% of the total oxygen consumption. Nitrification in the hypolimnion
contributed more to oxygen consumption in the eastern sites than western sites and was lowest in September.
The nitrification rate did not correlatewith environmental factors such as oxygen, nitrate or ammonium, or nitrifier
numbers. Oxygen consumption by nitrification in sediment slurries was 7.1 ± 5.8 μmol O2/g/d, with nitrification
accounting for 27.0 ± 19.2% of the total oxygen consumption with the lowest rates in July and the lowest
percentages in June. Oxygen consumption by nitrification in intact sediment coreswas 682 ± 61.1 μmol O2/m/d
with nitrification accounting for 30.4 ± 10.7% of the total oxygen consumption. Nitrification rates in intact cores
were generally highest in September. The proportion of oxygen consumed by nitrification corresponds closely
with what would be predicted from complete oxidation of a Redfield molecule (23%).While nitrification is unlikely
to be the dominant oxygen consumptive process, the rates observed in Lake Eriewere sufficient to theoretically
deplete a large portion of the hypolimnetic oxygen pool during the stratified period.

VOLUME: 40 ISSUE: 1 LENGTH: 5 pages
Reprint

Organic and inorganic nitrogen utilization by nitrogen-stressed cyanobacteria during bloom conditions

OHSU-RS-1502

Manuscript on nitrogen utilization by cyanobacteria

ABSTRACT:

Cyanobacterial blooms often occur in lakes that have high phosphorus (P) and low nitrogen (N) concentrations, and the growth rate of the blooms is often constrained by N. For these reasons, many researchers have suggested that regulation of both P and N is required to control eutrophication. However, because N occurs in many bioavailable forms, regulation of a particular form may be beneficial rather than regulation of all N forms. To address how N-stressed cyanobacteria respond to various N inputs, N enrichment experiments (nitrate, ammonium, urea, and alanine) were performed during N-limited cyanobacterial blooms in Maumee and Sandusky Bays of Lake Erie and in Grand Lake St. Marys (GLSM). Bioavailable N (nitrate, urea, and ammonium) concentrationswere also determined. Microcystis aeruginosa dominated the Maumee Bay bloom, where the highest growth rates were in response to ammonium additions, and lowest growth rates were in response to nitrate. Urea and the amino acid alanine resulted in intermediate growth rates. Planktothrix agardhii dominated the Sandusky Bay and GLSM blooms, where nitrate, ammonium, and urea addition resulted in similar growth rates. Additions of alanine did not stimulate growth of the Planktothrix blooms. Incubations using stable isotope 15N showed the cyanobacteria had a preference for ammonium, but the other forms were also assimilated in the presence of ammonium. These results show that cyanobacterial blooms will assimilate multiple forms of N to support growth. Thus, if lake managers do decide that N abatement is necessary, then all forms of bioavailable N need to be constrained.

DOI: 10.1007/s10811-013-0118-0 VOLUME: 26 ISSUE: 1 LENGTH: 10 pages
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