Marine Biology Commons^™

Effects Of Ph, Eelgrass, And Settlement Substrate On The Growth Of Juvenile Magallana (Crassostrea) Gigas, A Commercially Important Oyster Species, Johnny S. Roche

Cal Poly Humboldt theses and projects

Worsening ocean acidification (OA), resulting from ongoing absorption of atmospheric carbon dioxide (CO₂) by the oceans, threatens marine life globally. Calcifying organisms, especially their early life stages, are particularly vulnerable; this includes the economically important Pacific oyster, Magallana (Crassostrea) gigas. Uptake of dissolved CO₂ through photosynthesis by seagrasses, like eelgrass (Zostera marina), may benefit calcifying organisms by increasing pH and carbonate availability. I conducted laboratory and field experiments to quantify carbonate chemistry modification by eelgrass and potential mitigation of OA impacts on growth in juvenile Pacific oysters. In the laboratory experiment, daytime …

Comparison Of Modern And Mid-Holocene Benthic Foraminifera To Assess Recent Environmental Change In Almirante Bay, Caribbean Panama, Maria N. Gudnitz

FIU Electronic Theses and Dissertations

This study used the diversity and distribution of benthic foraminiferal assemblages of Almirante Bay, Caribbean Panama, as environmental proxies to compare modern coral, seagrass and mangrove habitats to mid-Holocene coral reef facies on the island of Isla Colón, to investigate both natural and human-influenced changes.

The modern study associated species and assemblage characteristics with environmental conditions related to degraded water quality. Assemblages were fairly similar among neighboring habitats but differed in species proportions, while several stress-tolerant taxa might indicate eutrophic conditions. Diversity appeared to be regionally controlled by freshwater input irrespective of habitat type, was generally lower near the mainland …

What Lies Beneath: Predicting Seagrass Below-Ground Biomass From Above-Ground Biomass, Environmental Conditions And Seagrass Community Composition, C. J. Collier, L. M. Langlois, Kathryn M. Mcmahon, J. Udy, M. Rasheed, E. Lawrence, A. B. Carter, M. W. Fraser, L. J. Mckenzie

Research outputs 2014 to 2021

© 2020 Seagrass condition, resilience and ecosystem services are affected by the below-ground tissues (BGr) but these are rarely monitored. In this study we compiled historical data across northern Australia to investigate biomass allocation strategies in 13 tropical seagrass species. There was sufficient data to undertake statistical analysis for five species: Cymodocea serrulata, Halophila ovalis, Halodule uninervis, Thalassia hemprichii, and Zostera muelleri. The response of below-ground biomass (BGr) to above-ground biomass (AGr) and other environmental and seagrass community composition predictor variables were assessed using Generalized Linear Models. Environmental data included: region, season, sediment type, water depth, proximity to land-based sources …

Climate Drives The Geography Of Marine Consumption By Changing Predator Communities, M. A. Whalen, R.D. B. Whippo, J. J. Stachowicz, (...), Paige G. Ross, Et Al

VIMS Articles

The global distribution of primary production and consumption by humans (fisheries) is well-documented, but we have no map linking the central ecological process of consumption within food webs to temperature and other ecological drivers. Using standardized assays that span 105° of latitude on four continents, we show that rates of bait consumption by generalist predators in shallow marine ecosystems are tightly linked to both temperature and the composition of consumer assemblages. Unexpectedly, rates of consumption peaked at midlatitudes (25 to 35°) in both Northern and Southern Hemispheres across both seagrass and unvegetated sediment habitats. This pattern contrasts with terrestrial systems, …

Positive Ecological Interactions And The Success Of Seagrass Restoration, Stephanie R. Valdez, Y. Stacy Zhang, Tjisse Van Der Heide, Mathew A. Vanderklift, Flavia Tarquinio, R J. Orth, Brian R. Silliman

VIMS Articles

Seagrasses provide multiple ecosystem services including nursery habitat, improved water quality, coastal protection, and carbon sequestration. However, seagrasses are in crisis as global coverage is declining at an accelerating rate. With increased focus on ecological restoration as a conservation strategy, methods that enhance restoration success need to be explored. Decades of work in coastal plant ecosystems, including seagrasses, has shown that positive species relationships and feedbacks are critical for ecosystem stability, expansion, and recovery from disturbance. We reviewed the restoration literature on seagrasses and found few studies have tested for the beneficial effects of including positive species interactions in seagrass …

Effects Of Reduced Ph On Health Biomarkers Of The Seagrass Cymodocea Nodosa, Regan A. Mcenaney

DePaul Discoveries

Ocean acidification is a growing problem that may affect many marine organisms in the future. Within 100 years the pH of the ocean is predicted to decrease to 7.8, from the current ocean pH of around 8.1. Using phenolic acid levels as a stress indicator as well as respiration and chlorophyll content as a measure of health, the effect of lowering pH was tested on the seagrass, Cymodocea nodosa, in a controlled environment. Plant samples, water, and soil were taken from the Bay of Cádiz, Spain, and placed in aquaria in a temperature-controlled room. One control group was left …

Undescribed Oomycete Pathogens On Zostera Marina And Z. Japonica In The Puget Sound, Theresa Proctor

Summer Research

A diverse range of marine organisms relies on seagrass as a foundational species. However, seagrass populations are declining at an alarming rate and recent analysis of seagrass root microbiomes indicates that oomycetes (fungi-like protists that are notorious terrestrial plant pathogens) infect up to 99% of seagrasses worldwide. Shockingly, very little is known about marine oomycetes and their ecological roles. The Elliott lab has isolated and cultured six oomycete species from eelgrass (Zostera marina) root samples: Phytophthora gemini, aHalophytophthoraspecies discovered by WSU, and four undescribed oomycete species. During the summer of 2018, I generated temperature and salinity growth curves and isolated …

The Importance Of Marine Predators In The Provisioning Of Ecosystem Services By Coastal Plant Communities, Trisha B. Atwood, Edd Hammill

Ecology Center Publications

Food web theory predicts that current global declines in marine predators could generate unwanted consequences for many marine ecosystems. In coastal plant communities (kelp, seagrass, mangroves, and salt marsh), several studies have documented the far-reaching effects of changing predator populations. Across coastal ecosystems, the loss of marine predators appears to negatively affect coastal plant communities and the ecosystem services they provide. Here, we discuss some of the documented and suspected effects of predators on coastal protection, carbon sequestration, and the stability and resilience of coastal plant communities. In addition, we present a meta-analysis to assess the strength and direction of …

Evaluating In Situ Grazing Patterns Of Lytechinus Variegatus And Their Effects On Seagrass Beds Of Thalassia Testudinum, Adrianna Parson

Master of Science in Integrative Biology Theses

The sea urchin Lytechinus variegatus is a known grazer of the seagrass Thalassia testudinum, and has been known to denude vast stands of seagrass beds at high densities. Outside of these denudation events, the effects of sea urchins on seagrass are poorly understood. This study examines the effects of L. variegatus on T. testudinum in situ, to understand how sea urchins are affecting seagrasses in situ. Results indicate that urchins were found in the offshore portion of the seagrass bed at densities up to 4 urchins/m². Changes in temperature and sediment size in the bay indicate …

Prioritizing Seagrass Meadows For Biodiversity Conservation Based On Landscape Connectivity, John Cristiani, Mary O'Connor

Salish Sea Ecosystem Conference

The spatial configuration of habitat and biological dispersal traits affect how organisms move across heterogenous landscapes, connecting populations and maintaining biodiversity. Quantifying this connectivity is critical to understanding and managing marine biodiversity. Despite its importance, for most regions, we lack estimates of connectivity and consideration of how habitat loss or restoration scenarios change connectivity and thereby affect diversity. We simulated dispersal and connectivity in several habitat change scenarios for seagrass habitats in the Salish Sea of British Columbia and Washington. We used a spatially explicit biophysical model to track passive larval dispersal in oceanographic currents for select life history traits. …

Seagrass Nursery Function Enhanced By Habitat Connectivity, Angeleen Olson, Margot Hessing-Lewis, Francis Juanes

Salish Sea Ecosystem Conference

Seascape connectivity is an emerging feature influencing marine ecosystem function. Connectivity, via the interplay of habitat configuration, its physical structure, and associated food webs, may alter the provision of nursery habitat, influencing the success of fish populations and harvests thereof. We quantified the effects of adjacent habitat type on seagrass nurseries for rockfish. We compared seagrass sites with contrasting structure and productivity in adjacent habitats: kelp forest and sand. To elucidate the spatially-dependent flow of material in the seagrass meadow, we estimated the proportion of basal contributions (producers) to the food web using an isotopic mixing model on YOY (young-of-the-year) …

Examining Sources Of Sediment Carbon Stored In Seagrass Habitats Across The Skagit Delta And Padilla Bay, Erin Murray

Salish Sea Ecosystem Conference

The potential for seagrass (Zostera marina) habitats to store carbon is a topic of interest to resource managers and ecosystem scientists as they strive to develop and evaluate climate change mitigation strategies. I investigated the sources of carbon and nitrogen stored in Zostera marina habitats within the Salish Sea. I compared two sites, the Skagit River delta (delta) and Padilla Bay (embayment), in order to compare carbon storage and the sources of stored carbon between these two shoreline types. Within each site, I collected sediment cores in Z. marina meadows and on unvegetated mudflat. I measured changes in carbon density …

North To South: Ecosystem Features Determine Seagrass Community Response To Sea Otter Foraging, Margot Hessing-Lewis, Erin U. Rechsteiner, Brent Hughes, M. Tim Tinker, Zachary L. Monteith, Angeleen M. Olson, Mathew Morgan Henderson, Jane C. Watson

Salish Sea Ecosystem Conference

We compared sea otter recovery in California (CA) and British Columbia (BC) to determine how key ecosystem properties shape top-down effects in seagrass communities. Potential ecosystem drivers of sea otter foraging in CA and BC seagrass beds that we examined include the role of coastline complexity and environmental stress on sea otter effects. In BC, we found greater species richness across seagrass trophic assemblages. Furthermore, Cancer spp. crabs, an important link in the seagrass trophic cascade observed in CA, was less common. Additionally, the more recent reintroduction of sea otters, more complex coastline, and reduced environmental stress in BC seagrass …

Does Eelgrass Act As An Ocean Acidification Refuge For Shellfish In The Salish Sea?, Bonnie Becker, Michelle Mccartha, Micah Horwith

Salish Sea Ecosystem Conference

Marine waters worldwide are becoming more acidic due to increasing atmospheric carbon dioxide levels. Changes in pH are heterogeneous in space and time and can be affected by physical and biological processes, including photosynthesis and respiration of plants and animals. Previous studies have shown that seagrass beds, which contain a large amount of plant biomass, can alter the carbonate chemistry in the immediate area, with higher pH during the day and lower pH at night. We explored the effects of this pattern on bivalve shellfish at four sites in Puget Sound and Willapa Bay. Pumped water samples were taken at …

Latitudinal Variation In Seagrass Wasting Disease From Puget Sound To Alaska, Olivia Graham, Corinne Klohmann, Emily Adamcyzk, Margot Hessing-Lewis, Angeleen Olson, Nick Tolimieri, Tiff Stephens, Colleen Amy Burge, Drew Harvell

Salish Sea Ecosystem Conference

Widely regarded as critical marine habitat, seagrass provides ecologically and economically valuable services in coastal areas worldwide. Eelgrass (Zostera marina) is one of five seagrass species native to the Pacific Northwest and is threatened by outbreaks of the marine protist Labyrinthula zosterae, the causative agent of seagrass wasting disease. Infection from L. zosterae causes necrotic lesions, limiting growth and compromising the health of eelgrass beds. To determine levels of wasting disease in subtidal eelgrass beds across a broad latitudinal gradient, we measured and compared disease prevalence and severity in 5 subtidal eelgrass beds in Puget Sound, 5 in the San …

Historical Change Of Seagrasses In The Mississippi And Chandeleur Sounds, Linh Thuy Pham

Dissertations

Seagrasses are important coastal resources facing numerous stressors, and losses have been documented from local to global assessments. Under the broad theme of habitat loss and fragmentation, a study of historical change in total area and landscape configuration of seagrasses in the Mississippi and Chandeleur Sounds was conducted. Mapping data was collated from a multitude of previous projects from 1940 to 2011.

Comparisons of seagrass area among various studies that used different mapping methods can result in overestimation of area change and misleading conclusions of change over time. The vegetated seagrass area (VSA) data were generalized to a common resolution …

The Population Genetics Of Morro Bay Eelgrass (Zostera Marina), Julia Gardner Harencar

Master's Theses

Seagrass populations are in decline worldwide. Zostera marina (eelgrass), one of California’s native seagrasses, is no exception to this trend. In the last 8 years, Morro Bay, California has lost 95% of its eelgrass. Eelgrass is an ecosystem engineer, providing important ecosystem services such as sediment stabilization, nutrient cycling, and nursery habitats for fish. The failure of recent restoration efforts necessitates a better understanding of the causes of eelgrass decline in this estuary. Previous research on eelgrass in California has demonstrated a link between population genetic diversity and eelgrass bed health, ecosystem functioning, and resilience to disturbance and extreme climatic …

Green Sea Turtles (Chelonia Mydas) In Bermuda Exhibit An Ontogenetic Diet Shift Despite Overexploitation Of Resources In Their Developmental Habitat, Claire Margaret Burgett

FIU Electronic Theses and Dissertations

Green sea turtles in Bermuda are overgrazing the seagrasses on which later life stages are thought to specialize. I hypothesized that larger green turtles in Bermuda would display individual diet specializations during seagrass scarcity. Stable isotope methods were used to determine the diet composition of green sea turtles from the Bermuda Platform as a function of size class and in turtles captured in successive years. Individual turtles had a wide range of diets, however, the variation in diets was driven by differences among size class rather than within the size classes of larger turtles, indicating that green turtles undergo a …

Investigating The Effects Of Changes In Light Quality On Different Life History Stages Of Seagrasses, Simone Strydom

Theses: Doctorates and Masters

Seagrass meadows provide crucial ecosystem services to the coastal zone but globally are threatened. Seagrass loss to date has mainly been attributed to anthropogenic activities that reduce light quantity, such as dredging, declining water quality from urban and agricultural run-off and eutrophication. However, light quality (wavelengths of light) is also altered by these anthropogenic stressors as well as natural events. This study consisted of three main components: (1) characterising light quality to which seagrasses are exposed across a local natural estuarine-ocean gradient and with a human impact pressure; (2) the influence of monochromatic light quality (blue λ=451 nm; green λ=522 …

Effects Of Catastrophic Seagrass Loss And Predation Risk On The Ecological Structure And Resilience Of A Model Seagrass Ecosystem, Robert J. Nowicki

FIU Electronic Theses and Dissertations

As climate change continues, climactic extremes are predicted to become more frequent and intense, in some cases resulting in dramatic changes to ecosystems. The effects of climate change on ecosystems will be mediated, in part, by biotic interactions in those ecosystems. However, there is still considerable uncertainty about where and how such biotic interactions will be important in the context of ecosystem disturbance and climactic extremes.

Here, I review the role of consumers in seagrass ecosystems and investigate the ecological impacts of an extreme climactic event (marine heat wave) and subsequent widespread seagrass die-off in Shark Bay, Western Australia. Specifically, …

Rare Occurrences Of Free-Living Bacteria Belonging To Sedimenticola From Subtidal Seagrass Beds Associated With The Lucinid Clam, Stewartia Floridana, Aaron M. Goemann

Masters Theses

Lucinid clams and their sulfur-oxidizing endosymbionts comprise two compartments of a three-stage, biogeochemical relationship among the clams, seagrasses, and microbial communities in marine sediments. A population of the lucinid clam, Stewartia floridana, was sampled from a subtidal seagrass bed at Bokeelia Island Seaport in Florida to test the hypotheses: (1) S. floridana, like other lucinids, are more abundant in seagrass beds than bare sediments; (2) S. floridana gill microbiomes are dominated by one bacterial operational taxonomic unit (OTU) at a sequence similarity threshold level of 97% (a common cutoff for species level taxonomy) from 16S rRNA genes; …

Temporal Variation In Optical Properties Of Chromophoric Dissolved Organic Matter (Cdom) In Southern California Coastal Waters With Nearshore Kelp And Seagrass, Catherine D. Clark, Warren J. De Bruyn, Paige Aiona

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Optical properties of chromophoric dissolved organic matter (CDOM) were measured in surf zone waters in diurnal field studies at a Southern California beach with nearshore kelp and seagrass beds and intertidal plant wrack. Absorption coefficients (aCDOM(300 nm)) ranged from 0.35 m21 to 3.7 m21 with short-term variability<1 h, increases at ebb and flood tides and higher values (6 m21) during an offshore storm event. Spectral slopes (S) ranged from 0.0028 nm21 to 0.017 nm21, with higher values after the storm; S was generally inversely correlated with aCDOM(300 nm). 3-D excitation–emission matrix spectra (EEMs) for samples with lower S values had humic-type peaks associated with terrestrial material (A, C), marine microbial material (M) and protein peaks, characteristic of freshly produced organic material. Samples with high S values had no or reduced protein peaks, consistent with aged material. Fluorescent indexes (f450/f500 >2.5, BIX>1.1) were consistent with microbial aquatic sources. Leachates of senescent kelp and seagrass had protein and humic-type EEM peaks. After solar simulator irradiation (4 h), protein peaks rapidly photochemically degraded, humic-type peak C increased in intensity and peak M disappeared. Optical characteristics of kelp leachates were most similar to field samples, …

Sarpa Salpa Herbivory On Shallow Reaches Of Posidonia Oceanica Beds, Latina Steele, Kelly M. Darnell, Just Cebrián, Jose Luis Sanchez-Lizaso

Biology Faculty Publications

Sarpa salpa herbivory on shallow reaches of Posidonia oceanica beds.— Here, we examined the temporal and small–scale spatial variability of grazing by the herbivorous fish Sarpa salpa on shallow beds of the temperate seagrass Posidonia oceanica. Herbivory intensity expressed as the percent of leaf area taken by fish bites was higher in September 2006 than in February 2007, and at 0.5 m than at 1.5 m during both sampling times. All S. salpa feeding at the shallow locations studied were juveniles, with bite sizes ranging from 0.03 to 0.62 cm2. Juveniles feeding at 1.5 m were larger in February 2007 …

Development And Application Of A Gis-Based Long Island Sound Eelgrass Habitat Suitability Index Model, Jamie M.P. Vaudrey, Justin Eddings, Christopher Pickerell, Lorne Brousseau, Charles Yarish

Department of Marine Sciences

The primary objectives of the Eelgrass Habitat Suitability Index Model (EHSI Model) are to assist in the evaluation of sites being considered for eelgrass restoration efforts in the Long Island Sound (LIS) area and to identify areas where water quality issues reduce or eliminate the potential for natural eelgrass colonization. To achieve this goal, geospatial processing of data available from the Long Island Sound area was conducted using ArcGIS v10.0 including the 3D Analyst and Spatial Analyst extensions. The result is a series of maps presented in this report and a GIS-based model available for users to interact with the …

Relating Water And Otolith Chemistry In Chesapeake Bay, And Their Potential To Identify Essential Seagrass Habitats For Juveniles Of An Estuarine-Dependent Fish, Spotted Seatrout (Cynoscion Nebulosus), Emmanis Dorval

Biological Sciences Theses & Dissertations

A quantitative understanding of habitat use of estuarine-dependent fishes is critical to the conservation of their most essential habitats. Because recruitment and fitness may be influenced by the quality of juvenile habitats, developing methods to quantify habitat-specific survivorship is pivotal to such understanding. An initial step to quantify survivorship is to validate the habitat-specific natural tags contained in otoliths. To this aim I investigated the variability in the chemistry of surface waters and otoliths of juvenile spotted seatrout, Cynoscion nebulosus, in five seagrass habitats of Chesapeake Bay, namely: Potomac, Rappahannock, York, Island, and Eastern Shore. I measured Mg, Ca, …

Effect Of Light/Dark Transition On Carbon Translocation In Eelgrass Zostera Marina Seedlings, Richard C. Zimmerman, Randall S. Alberte

OES Faculty Publications

Carbon translocation in the marine macrophyte Zostera marina L. (eelgrass) was investigated to elucidate the impact of light/dark transitions on sucrose partitioning between roots and shoots. After exposure of leaves to C-14-bicarbonate, the level of C-14-labelled photoassimilates increased monotonically in both leaves and fully aerobic roots of plants maintained in the light. Accumulation of C-14 in roots and leaves ceased abruptly when plants were transferred to darkness that induced root anaerobiosis even though C-14 levels remained high in the dark-exposed leaves. Thus, translocation of C-14 photoassimilates from shoots to roots was inhibited when roots became anoxic. Anoxia induced by light …