This is a general session covering topics in Plankton Ecology.
Lead Organizer: Kerri Finlay, University of Regina (kerri.finlay@uregina.ca)
Co-organizers:
Beatrix Beisner, University of Quebec at Montreal (beisner.beatrix@uqam.ca)
Angela Strecker, Western Washington University (angela.strecker@wwu.edu)
Presentations
05:30 PM
New Hyperspectral Absorption and Backscattering Instruments for Ocean Color and Biogeochemistry (8119)
Primary Presenter: Kirby Simon, Sequoia Scientific, Inc. (kirby.simon@sequoiasci.com)
Measurements of in-water absorption and backscattering with coincident in situ and satellite-measured radiometry are keys to refining and calibrating ocean color algorithms and developing next generation (e.g., NASA PACE) hyperspectral ocean color products such as phytoplankton community composition. Beyond ocean color applications, these in situ instruments also offer the capability to measure particle and dissolved material properties directly applicable to ocean biogeochemistry research. Currently, commercial instruments exist for in situ measurement of hyperspectral radiometry and absorption coefficient, while measuring backscattering with a single instrument has been limited to multispectral. We have developed and commercialized a new submersible single-angle hyperspectral backscattering sensor using a white LED source, linear variable bandpass, and a sensitive photomultiplier detector. More recently, we have also developed a new hyperspectral absorption sensor using an integrating cavity to reduce measurement uncertainty due to scattering errors inherent in the reflective tube design. This new design also employs a solid standard for routine field calibration to avoid uncertainties and difficulties associated with field calibration using nigrosine solution standards. We will present details of the backscattering and absorption instruments, challenges underlaying hyperspectral IOP instrument design, results of characterization and calibration studies, and field data including an examination of closure between inherent optical properties (IOPs) and radiometry.
05:30 PM
USING LONG-TERM STATEWIDE MONITORING DATA TO EXPLORE THE EFFECTS OF LANDSCAPE AND PHYSIOCHEMICAL DRIVERS ON PHYTOPLANKTON COMMUNITY COMPOSITION AND DIVERSITY (7789)
Primary Presenter: Jasmine Stovall, Baylor University (jasmine.stovall92@gmail.com)
Phytoplankton are widely regarded as indicator organisms within aquatic ecology and are commonly used as an ecological tool in assessing water quality and indicating ecosystem health. The purpose of this study was to explore the effects of landscape and physiochemical drivers on variation in phytoplankton community composition and diversity in lakes across the state of Oklahoma. We hypothesized that variation in phytoplankton communities is primarily driven by both landscape and physiochemical variables, specifically precipitation, longitude, nitrogen, and phosphorus. To test this hypothesis, we acquired 438 surface water samples collected during a three-year period from 109 lakes in Oklahoma through a statewide water quality monitoring program. All phytoplankton samples were counted using compound light microscopy and identified to genus level. Community data analyses were performed to assess spatial variation in community composition and whether the variation can be explained by the physiochemical and landscape variables. We found significant relationships between phytoplankton diversity and developed land, chlorophyll-a, conductivity, DO, pH, temperature, and turbidity. Overall, the analysis identified one landscape variable and six physiochemical variables as significant drivers suggesting that physiochemical variables are more predictive of variation in community composition than landscape variables. Our findings emphasize the continued need to focus on in-lake characteristics for maintaining water quality standards and minimizing the risk of HABs.
05:30 PM
Strain-delineated composition and spatiotemporal dynamics of cyanobacteria throughout nutrient gradients in a eutrophic, freshwater lake (8357)
Primary Presenter: Krystyn Kibler, University of Wisconsin - Madison (kjkibler@wisc.edu)
The composition and dynamics of cyanobacterial communities in freshwater lakes has been studied intensively to explain the timing and intensity of harmful cyanobacterial blooms. Although, there is a knowledge gap in how these communities evolve and move in their lake systems, as well as, how comparable these separate communities are to each other. For this, we have used shotgun metagenomics on shoreline samples around Lake Mendota, a eutrophic, freshwater lake, to obtain cyanobacteria assemblage snapshots. These samples are throughout the typical cyanobacterial growing season and were collected before and after periods of high wind or rain. Additionally, a portion of samples were collected across a nutrient gradient from the Yahara River outlet into Lake Mendota towards the center at the Deep Hole sampling site. In this study we use a combination of meta’omics and time lag analyses to assess how cyanobacteria communities change throughout the season and especially in response to nutrient pulses. Additionally, we use a variety of microdiversity metrics, such as single nucleotide variations, to compare these separated communities’ genomes. These results all can be used to improve our understanding of cyanobacterial bloom compositions across space and time, which can be used to improve bloom forecasting.
05:30 PM
MEASURING PHOTOSYNTHETIC HEALTH IN CULTURES OF THE HAPTOPHYTE CHRYSOCHROMULINA PARVA (7801)
Primary Presenter: Sophie Anderson, University of Toronto (sophie.anderson@mail.utoronto.ca)
Simultaneous analysis of carbon assimilation and chlorophyll fluorescence provides insights into algal photosynthetic health and primary productivity. Chrysochromulina parva is a widely distributed freshwater haptophyte that can be infected with multiple viruses isolated from Lake Ontario. The goal of our research is to determine if viruses have an impact on C. parva’s photosynthetic performance and carbon fixation. Recently we isolated C. parva cells that recovered after infection with the virus CpV-BQ1. These virus-resistant cells continue to divide while also producing viruses raising questions about their physiological status and photosynthetic efficiency. Initially, a LI-COR® 6800 was used to generate light response curves (i.e., photosynthesis vs. irradiance) and measure the fluorescence parameters Fv/Fm and PhiPS2 for both resistant C. Parva and naïve C. parva that hadn’t been exposed to viruses. When normalized to cell abundance, and across irradiances ranging from 100 to 1000 micromole m-2 s-1, carbon assimilation was consistently ~1.5x higher for naïve C. parva cells compared to resistant cells. Further, PhiPS2 values, which indicate photosynthetic efficiency, were between 1.15-1.3x higher for naïve cells at irradiances ranging from 300 to 900 micromole m-2 s-1. Following this pilot experiment which revealed differences in photosynthetic performance between naïve and BQ1-resistant cells, additional growth experiments will be conducted to determine if this pattern is robust and directly demonstrate a virus’s influence on C. parva’s photosynthetic efficiency.
05:30 PM
CELL VOLUME AS A DETERMINANT OF VIRUS-MEDIATED POPULATION GROWTH IN CILIATES (8150)
Primary Presenter: Jace Miller, University of Nebraska-Lincoln Lib - Lincoln, NE (jace.k.miller2000@gmail.com)
Many protist species consume viruses, a behavior known as virovory. Some species, such as the ciliate <em>Halteria grandinella<em>, can grow with viruses as their sole food source. Many other ciliate species have been documented consuming viral particles, but virovory’s impacts on their populations’ growth remain unclear. We hypothesize that virovory is not unique to <em>Halteria<em>, and that other species will show similar population growth when fed viruses. Because ciliates’ energy demands increase significantly with size, we also hypothesize that cell volume is one of the key factors influencing ciliate species’ ability to subsist on viruses. To test these hypotheses, we fed nine ciliate species of varying sizes and genera a diet of viruses over a two-day period. We found that most species’ populations grew better with access to viruses, supporting our first hypothesis. However, this growth was independent of ciliate cell volume, and even varied significantly between species with otherwise similar morphologies, such as the three <em>Paramecium<em> species. These results do not support our second hypothesis and are cause for further investigation. Taken together, these data suggest that virovory-driven population growth is widespread among ciliates, even if the physiological factors which determine virovory’s effects on population growth remain unknown. Because ciliates are a key node in most aquatic food webs, widespread virovorous behavior may have important implications for energy at nutrient transfers at higher trophic levels than previously realized.
05:30 PM
METHOD DEVELOPMENT OF WHOLE ORGANISM DNA EXTRACTION TECHNIQUES FOR DIET CHARACTERIZATION OF DAPHNIA MAGNA USING 16S AND 18S RDNA AND NEXT-GENERATION SEQUENCING. (7929)
Primary Presenter: Ciaran Edwards, Niagara University (ciaranowls@gmail.com)
The role of zooplankton in linking producers to higher trophic levels is essential to understanding carbon and nutrient cycling. New approaches are needed for diet characterization of freshwater zooplankton because fatty acid profiles, stable isotopes, pigments, and molecular work on dissected guts are not practical for smaller, freshwater, organisms. Recently, whole organism extraction of prey DNA has been demonstrated on estuarine copepods. Here, we develop a whole organism DNA extraction technique for the freshwater cladoceran, Daphnia magna, to assess diet through 16S rDNA sequences in controlled laboratory experiments. Lab raised D. magna were placed in feeding microcosms containing three monoculture strains of Synechococcus for 24 h in varying ratios, monocultures of each taxon, and a eukaryote, Chlorella, control. We amplified the 16S rDNA V3-V4 region after DNA extraction, then purified our target fragment by excising the band from an agarose gel. We have found this step important for successful sequencing due to the large amount of non-target Daphnia mitochondrial DNA that was being amplified. We then sequenced the V3-V4 amplicons using Illumina MiSeq and compared them to the sequences of the three feeding microcosms. The D. magna showed feeding preference towards Synechocystis sp. over Synechococcus sp. We successfully demonstrated the effectiveness of this new technique for assessing diet through whole organism extraction. This method will be a tool in assessing trophic cycling of carbon and nutrients in freshwater ecosystems.
05:30 PM
FIELD TESTING CHARACTERIZATION OF LOWER NIAGARA RIVER DAPHNIA DIET USING 16S RRNA AND 18S RRNA GENE SEQUENCING (7933)
Primary Presenter: Samantha Wrobel, Niagara University (swrobel@mail.niagara.edu)
Zooplankton regulate the flow of carbon and nutrients from phytoplankton to higher trophic levels. Previous efforts to differentiate food choice have focused on fatty acid profiles and stable isotopies, with the recent efforts in genetic identification of prey in dissected guts of larger marine zooplankton. Our work clarifies the energy and nutrient flow in their respective ecosystems. We have developed and lab tested a technique to determine diet content in a model zooplankton, Daphnia, using rDNA extraction through whole organism digestion. In this study, we field tested this method by determining the diet of Daphnia galeata collected from the lower Niagara River, NY and compared this to the phytoplankton community. We extracted DNA from whole D. galeata and river water phytoplankton samples followed by amplicon sequencing of the 16S rRNA V3-V4 region and 18S rRNA V4 region. The D. galeata selected Micrococcales, despite Frankiales and Microtrichales being most prevalent bacterial genera in the water column, and chose Monogononta over the more prevalent alga Cladophorales, suggesting selective feeding. Moving forward, we will be able to use this method successfully developed in the Niagara River to understand feeding patterns and nutrient cycling in other major lake and river systems.
05:30 PM
MECHANISMS DRIVING ZOOPLANKTON SPECIES COMPOSITION OF HIGH ALPINE LAKES (7946)
Primary Presenter: Florian Hohenberger, University of Salzburg (florian.hohenberger@plus.ac.at)
Zooplankton species in high alpine lakes face harsh conditions in extreme environments, with low productivity and short ice-free periods. Due to warming in alpine regions these hostile environments are rapidly changing, with earlier ice out, increasing water temperatures, and potential changes in productivity and accessibility. This has the possibility to both create habitats more amenable to lowland zooplankton species and to provide more opportunities for lowland species to colonize these habitats, leading to alternate species composition in the lakes. Within a transdisciplinary project, potential barriers to colonization (competitive exclusion, harsh environments) within the zooplankton community of the lakes of the National Park Hohe Tauern, Austria, have been investigated, with the following hypnoses: 1. When large zooplankton species are already present in a lake, they can preclude invasion by new lowland species through competitive exclusion. 2. The hostile environment (low temperature and productivity, high turbidity) of some high alpine lakes is limiting the colonization success of invading species. Based on the results of the long-term monitoring of 18 lakes of the National Park Hohe Tauern, Austria, model lakes were chosen and the water and species from these lakes used to run experiments in the lab under controlled conditions. The results of the first experiments testing our hypotheses will be presented.
05:30 PM
Temporal Population Dynamics of Zooplankton Drifting in Great Plains Reservoirs (8210)
Primary Presenter: Joshua Matthews, University of Nebraska-Lincoln (jmatthews6@huskers.unl.edu)
Zooplankton play a significant role in aquatic food webs; however, their population dynamics in the Great Plains have not been thoroughly documented or studied. To understand potential controls on zooplankton populations, we have conducted monthly samplings of two reservoirs near a medium-sized city (Lincoln, NE). We hypothesize that zooplankton populations will be affected by seasonal variables, such as temperature and light, and available chemical energy including total nitrogen, phosphorus, and other stoichiometric variables. Each month, zooplankton samples were identified, counted, and analyzed for carbon, nitrogen, and phosphorus content. Additionally, water samples were collected for phytoplankton biomass and nitrogen and phosphorus content. Our initial findings suggest zooplankton populations are dynamic over winter. In both reservoirs, between October and January, Bosmina became less prevalent (from 61% down to 3%) while calanoids progressively made up a larger percentage of all zooplankton (up to 72%). Initial observations suggest complex interactions between environmental and stoichiometric variables drive zooplankton populations in Great Plains reservoirs. These ongoing observations will help reveal how zooplankton, a key lentic food web component, may be impacted by eutrophication, climate change, and shifts in hydrologic regimes in understudied freshwater systems of the Great Plains.
05:30 PM
Integrative Metagenomics of Great Lakes Zooplankton Utilizing a Three-Marker Approach (8247)
Primary Presenter: Nitin Vincent, University of Notre Dame (nvincen2@nd.edu)
Zooplankton are essential components of Great Lakes ecosystems, playing pivotal roles in nutrient cycling and trophic dynamics. Current taxonomic assessment strategies for these taxa are either underdeveloped or resource-intensive, which impedes biodiversity monitoring in the face of rapid ecological change. This study employs a novel approach utilizing a three-marker metabarcoding technique for zooplankton biodiversity assessment to enhance taxonomic recovery while minimizing sequencing costs. Bulk zooplankton samples were collected using mesh nets from 96 stations across the Great Lakes. DNA was PCR amplified using 2 overlapping COI fragments and one 18S fragment, which were pooled prior to sequencing. Sequence reads were de-multiplexed by marker and assigned taxonomy through the RDP classifier implemented in dada2 against a reference database constructed from sequence data in the Barcode of Life Database (BOLD) and the SILVA database for COI and 18S markers respectively. The metabarcoding method proved more sensitive in detecting rare and cryptic species compared to traditional morphological identification. These findings highlight the potential of multi-marker metabarcoding as a standard practice in aquatic monitoring projects, facilitating the tracking of taxonomic changes and the detection of species invasions.
05:30 PM
EVALUATION OF SAMPLE SHIPPING, HANDLING, AND STORAGE ON ALGAL PIGMENTS (CHLOROPHYLL A AND PHYCOCYANIN) (8171)
Primary Presenter: Stephen Shivers, USEPA (shivers.stephen@epa.gov)
Large scale (i.e. continental United States) aquatic resource surveys often collect samples and ship to a centralized processing laboratory. The rigors and chosen methods of shipping and handling as well as holding time could impact the integrity of algal pigments. This study examined the effects of a variety of simulated handling approaches and holding times on the degradation of chlorophyll and phycocyanin. An equal mixture of two green algae and two cyanobacteria cultures were filtered onto 370 GF/F filters and were assigned to treatments (five replicates per treatment). Treatments were used to evaluate holding time effects on filters stored at -20 °C, placed on or sandwiched between ice in a shipping cooler, and number of days in the shipping cooler. Pigments were extracted using a solvent-based extraction (90% acetone for chlorophyll a and 50 mM phosphate buffer for phycocyanin) and analyzed using a Turner Trilogy fluorometer. Preliminary analysis indicated a 15% loss of chlorophyll a and a 375% increase in phycocyanin after 60 days of holding at -20 °C. No significant differences between handling treatments were observed for chlorophyll a, whereas significant decreases were observed for all phycocyanin handling treatments. These results indicate that chlorophyll a on filters can be held with minimal loss for 60 days before analysis, and shipping and handling does not affect pigment degradation. Conversely, phycocyanin on filters were strongly affected suggesting that more research is needed to explain the increases during storage as well as the losses during shipping.
CS26P - Plankton Ecology
Description
Time: 5:30 PM
Date: 4/6/2024
Room: Madison Ballroom D