Marine Biology Commons^™

Understanding Ecosystem Responses To Recurrent Marine Heatwaves, Emily Lester, Stanley Mastrantonis, Sharyn M. Hickey, Anna Lafratta, Jessica A. Benthuysen, Eben Afrifa-Yamoah, Arani Chandrapavan, Martial Depczynski, Richard D. Evans, David V. Fairclough, Christopher J. Fulton, Marthe Monique Gagnon, Nicole L. Jones, Sina Pinter, Claire L. Ross, William D. Robbins, Zoe T. Richards, Karina L. Ryan, Simone Strydom, James R. Tweedley, Fred Wells, Hollie Williams, Shaun K. Wilson, Kathryn Mcmahon

Research outputs 2022 to 2026

Marine heatwaves (MHWs) have emerged as an increasingly severe disturbance to global marine ecosystems, with documented intensifications in both frequency and magnitude over the past century. Western Australia has experienced some of the most severe MHWs on record, causing widespread ecological impacts, including coral bleaching and mortality, local species extinctions, and socioeconomic impacts such as fishery closures, making the region a critical case study of climate-driven change in the marine domain. Most recently, a severe MHW during summer 2024/2025 has caused widespread disruption to marine life, reinforcing the region's vulnerability to repeated extreme events. While extensive research has documented the …

Assessing Gene Expression Changes In The Octocoral Briareum Asbestinum Due To Vibrio Coralliilyticus Exposure, Hailey Poignant

All HCAS Student Capstones, Theses, and Dissertations

Coral reefs are an essential ecosystem home to tons of marine diversity that humans have also  learned to rely on, but they are harmed by climate change and the increasing prevalence of disease. While most studies focus on reef-building coral, octocorals also warrant attention to reveal how they respond to similar stressors. Octocorals share distant ancestry with reef-building corals, so there may be overlap in their immune responses which could provide insight into future restoration projects. To understand how octocorals respond to disease, the octocoral Briareum asbestinum was used as a model to examine gene expression changes caused by the …

Blue Crab Reproductive Output And Phenology In A Changing Climate, Blaise Rohan

Master's Theses

Globally, ecosystems are experiencing rising temperatures due to climate change, with potential consequences for reproductive investment and timing in many species. Blue crabs, Callinectes sapidus, support valuable commercial fisheries throughout the U.S. Atlantic and Gulf coasts, and understanding variation in reproductive output has important management and conservation implications. This study examined two components of blue crab reproduction: (1) reproductive investment across populations spanning multiple latitudes (New York, New Jersey, North Carolina, Mississippi, and Texas), using a space-for-time substitution to assess the effects of varying thermal regimes on fecundity and egg quality, and (2) spawning phenology in North Carolina from …

Just Unmasking Knowledge? A Critical Interpretation Of Fluctuating Jellyfish Populations For A Mass Media Audience, Wrenne R. Grone

Undergraduate Honors Thesis Projects

While podcasts may not be the most popular form of mass media, they are growing in their accessibility and prevalence in educational discourse. My creative work, in the form of a podcast, unmasks scientific knowledge in an untraditional, mass-media form and will use podcast techniques, such as music transitions and storytelling techniques, to maintain engagement. Additionally, my podcast aims to transpose academic knowledge into a comprehensible, interesting form for a non-academic audience. Jellyfish have no brains, no heart, no blood, and no bones and yet, they have survived for millions of years. The goal of my podcast is to educate …

A Marine Science Career In The Eastern Caribbean: Witnessing Four Decades Of Change, Hazel A. Oxenford

Gulf and Caribbean Research

Reflecting back on a long and rewarding career from 1980—2023 at the University of the West Indies, based on the small island of Barbados, this paper tracks the many and often remarkable changes in the marine environment, in attitudes and policies, and available opportunities that have influenced my journey as a marine scientist in an ever—changing but resilient Caribbean. From free—access fisheries to degraded stocks, from coral to algal dominated reefs, from flyingfish to Almaco Jacks, from sandy beaches and clear water to a Sargassum crisis — these are just some of the fundamental changes in the marine environment that …

The Influence Of Localized Water Quality On Eastern Oysters (Crassostrea Virginica) And Their Internal Microbiome Under Changing Environmental Conditions, Jessie Rivera Lafreniere

College of Graduate Studies: Theses & Dissertations

Oysters are found ubiquitously in estuaries along the Georgia coast, where marsh morphology and large daily tidal fluctuations create dynamic and stressful conditions to which oysters may be locally adapted. Based on water quality data from the Sapelo Island National Estuarine Research Reserve, it is evident that changing climatic conditions are rapidly causing shifts in water quality that may be adversely affecting oyster health, especially as ocean acidification alters the carbonate buffering capacity, increasing the amplitude of daily pH variations. Importantly, the rate of change of conditions are not uniform within estuaries, varying on spatial and temporal scales. The symbiotic …

Breaking Down Seagrass Fragmentation In A Marine Heatwave Impacted World Heritage Area, Michael D. Taylor, Simone Strydom, Matthew W. Fraser, Ana M.M. Sequeira, Gary A. Kendrick

Research outputs 2022 to 2026

Marine heatwaves, and other extreme climatic events, are driving mass mortality of habitat-forming species and substantial ecological change worldwide. However, habitat fragmentation is rarely considered despite its role in structuring seascapes and potential to exacerbate the negative impacts of habitat loss. Here, we quantify fragmentation of globally significant seagrass meadows within the Shark Bay World Heritage Area before and after an unprecedented marine heatwave impacting the Western Australian coastline over the austral summer of 2010/11. We use a spatial pattern index to quantify seagrass fragmentation from satellite-derived habitat maps (2002, 2010, 2014 and 2016), assess potential predictors of fragmentation and …

Geographic Variation In Proteomic Responses To Ocean Acidification In A Cold-Water Coral (Balanophyllia Elegans), Keana A. Richmond

Cal Poly Humboldt theses and projects

In the face of a rapidly changing climate, assessing organismal responses to future stressors in the context of current, natural exposure to stress could provide key insights to understanding marine ecosystem resilience. I used Balanophyllia elegans, a cold-water, solitary, azooxanthellate coral as a model to better understand how varying oceanographic conditions across its geographic range have shaped its ability to tolerate and potentially adapt to current and future ocean acidification conditions. I collected B. elegans individuals from four sites across 2,500km of their range and subjected them to two pH treatments to investigate site-specific protein expression in response to …

High Coral Thermal Tolerance At A Potentially Climate-Resistant Reef, Kate M. Quigley, C. Siqueira, Kira Brereton, Andrew H. Baird

Research outputs 2022 to 2026

Ecosystems globally are under increasing pressure from warming caused by climate change. However, some locations appear resistant to impacts. Although rare, these locations might be able to better resist damage from thermal stress. In marine environments, coral bleaching is widely viewed as one of the most pervasive stress responses threatening reef health, structure, and function. Yet we still have a poor understanding of the drivers of spatial and temporal variation in the scale and severity of coral bleaching. Here, we characterize a prolonged, intense, and widespread marine heatwave event and uncover a conspicuous lack of bleaching at the southernmost coral …

Population Genomics Data For The Temperate Seagrass Posidonia Sinuosa, John Whale, Elizabeth Sinclair, Chanelle Webster, Nicole Said, Ankje Frouws, David Field, Kathryn Mcmahon

Research Datasets

Seagrasses are flowering plants commonly found along coastal waters, globally, where they provide important ecosystem services such as habitat provision, sequestering carbon, and sediment stabilization. They can reproduce both clonally and sexually where sexual reproduction can result in new, potentially adaptive, variants and the existence of both reproductive methods means that meadows can be highly variable in clonal diversity. The temperate seagrass, Posidonia sinuosa, occurs across a latitudinal gradient along the Western Australian coastline. Some meadows have experienced significant decline as a result of industrialisation and urbanisation of coastal areas. We investigated spatial genetic diversity, structure, and local adaptation using …

The Transition Zone Hypothesis On Biodiversity Of The Indian River Lagoon System, Florida, Richard L. Turner

Ocean Engineering and Marine Sciences Faculty Publications

The Indian River Lagoon System (IRL) is regarded as having a high level of biodiversity. The level of biodiversity is often attributed in part to the 2-degree latitudinal span (251 km) of the IRL and to its position in a transitional zone between tropical and temperate biotic provinces. This hypothesis was tested for submerged aquatic vegetation (SAV) based on a recent treatise (Littler, Littler, and Hanisak, 2008). Five of seven species of seagrass are tropical, and two have either a broad or very narrow latitudinal distribution; the transition-zone hypothesis does not hold for seagrasses. Most macroalgae (131 spp.) are tropical/subtropical; …

Trophic Roles And Climate-Driven Vulnerability For Benthic Invertebrates At Artificial Reefs In The Northern Gulf Of Mexico, Amanda Kirkland

LSU New Orleans Theses and Dissertations

Artificial reefs are deployed to enhance marine habitats and fisheries, yet their role in supporting secondary production and their vulnerability to climate stressors remain understudied. This dissertation investigates the trophic ecology and climate sensitivity of benthic invertebrates at artificial reefs in the northern Gulf of Mexico. Chapter 1 assessed reef food webs using stable isotopes from fishes, invertebrates, and primary producers across six reefs and two seasons. Mixing models showed that most fishes rely on benthic reef carbon, while suspension feeders consume plankton and sediment microphytobenthos. Isotopic niche analysis revealed functional diversity and seasonal shifts in δ¹³C and δ³⁴S, though …

Reevaluating The Role Of Ruppia Maritima: Recruitment Dynamics And Habitat Use By Blue Crabs (Callinectes Sapidus) And Associated Benthic Fauna In A Mid-Atlantic Seagrass Community, Delaney St. Pierre

Theses, Dissertations and Culminating Projects

The value of seagrasses as essential fish habitat is well recognized, but limited data exist on the value of one particular species, Ruppia maritima (widgeon grass), as habitat for fish and invertebrates. During the summer of 2024, I evaluated R. maritima, Zostera marina (eelgrass) and mixed beds to assess their relative value as habitat in Barnegat Bay, New Jersey. Results from throw traps indicated significant monthly differences for pipefish, gobies, blue crabs, grass shrimp, and sand shrimp, driven by active recruitment events. When evaluating habitat type, we found no taxa that were significantly more abundant in Z. marina habitat as …

Drivers Of Seagrass Decline In Perth Waters And Actions To Halt Decline, Kathryn Mcmahon, Simone Strydom, Natasha Dunham, John Whale, Chanelle Webster, Nicole Said

Research outputs 2022 to 2026

Executive summary:

• Experts from consulting, government and research including individuals with up to 50 years’ experience in Perth coastal waters discussed potential drivers of seagrass decline based on trends from the long-term seagrass monitoring program in Cockburn and Warnbro Sound and Owen Anchorage (27 sites from 2003-2020) and their personal knowledge and expertise.

• The collation of seagrass monitoring data demonstrated that of the 27 sites monitored, only six had a significant decline over time, and these sites were both within and outside of Cockburn Sound (Warnbro Sound, Southern Flats, Jervoise Bay, Garden Island and Woodman Point).

• For …

Recommendations For Strengthening Blue Carbon Science, Martin Dahl, Paul S. Lavery, Inés Mazarrasa, Jimena Samper-Villarreal, Maria F. Adame, Stephen Crooks, Carlos M. Duarte, Daniel A. Friess, Dorte Krause-Jensen, Carmen Leiva-Dueñas, Catherine E. Lovelock, Peter I. Macreadie, Pere Masqué, Miguel Angel Mateo, Oscar Serrano

Research outputs 2022 to 2026

Blue carbon (BC) habitats (e.g., mangroves, tidal marshes, and seagrasses) are important CO2 sinks but are among the most threatened ecosystems on Earth. Substantial research over the last decade has quantified BC to evaluate the climate benefits associated with habitat conservation and restoration. However, the exponential growth in BC science has resulted in differing approaches that hinder comparison across studies and increase uncertainty. Here, we synthesized existing data to depict the range of uncertainty associated to different BC methodologies and argue that cumulative biases linked to multiple methodologies can result in BC estimates differing by up to 10-fold. We identified …

Operationalizing And Measuring Climate Change Adaptation Success, Henry A. Bartelet, Michele L. Barnes, Lalu A.A. Bakti, Graeme S. Cumming

Quantitative Methods and Information Technology Faculty Publications

In a context of rapid global change, understanding whether and how adaptation to climate change can be considered successful has become an important research gap within the climate change adaptation literature. Although definitions of adaptation success have been formulated, it remains unclear how they can be operationalized and tested empirically. To address this gap, we operationalized one of the most prominent definitions of successful adaptation within the academic literature, which describes success as adaptations that support reductions in risk and vulnerability without compromising sustainability. Specifically, drawing on data collected from 209 coral reef tourism operators across 28 locations and eight …

Investigating The Refugial River Mouth Hypothesis: Assessing The Effects Of Low Salinity Conditions On The Microscopic Life Stages Of Nereocystis Luetkeana, Duncan Jackson

Cal Poly Humboldt theses and projects

Populations of Nereocystis luetkeana (bull kelp) have experienced localized extinction events in northern California since 2014 due to multiple stressor events, including the area’s most severe marine heatwave (MHW) to-date. Previous surveys in the region observed that bull kelp recovered and persisted at river mouths following the 2014-2015 MHW, suggesting that river mouths may serve as refugia – the refugial river mouth hypothesis. My study aimed to assess this hypothesis and the long-term stability of these refugia by studying how freshwater influences communities at these sites and bull kelp recruitment. Field surveys of salinity fluctuation and kelp and sea urchin …

Varying Vulnerabilities: Seagrass Species Under Threat From Prolonged Ocean Warming, Marnie L. Campbell, Chi T.U. Le

Research outputs 2022 to 2026

Understanding the response of various seagrass species to prolonged elevated water temperatures is crucial for effective management and seagrass species restoration amid increasing climate change-induced ocean warming and marine heat waves. This is especially important in intertidal seagrass meadows, where heat can penetrate substrate depths of up to 50 cm. We assessed and contrasted the responses of five intertidal species—Zostera muelleri Irmisch ex Asch, Halophila ovalis (R.Br.) Hook f., Halodule uninervis (Forssk.) Asch, Halophila decipiens Ostenf., and Halophila spinulosa (R.Br.) Asch—over a month of elevated temperatures by examining rhizome growth, number of living shoots, root development, and sprig survival. While …

Seagrasses Are Most Vulnerable To Marine Heatwaves In Tropical Zones: Local-Scale And Broad Climatic Zone Variation In Thermal Tolerances, Nicole Said, Chanelle Webster, Simone Strydom, Natasha Dunham, Matthew P. Adams, Kathryn Mcmahon

Research outputs 2022 to 2026

Under a changing climate, it is imperative that we understand how species may respond to temperature impacts, which can differ among populations of the same species due to local drivers. Thermal tolerance data, which can be used to assess an organism's upper thermal limits, is valuable to identify species and/or populations' susceptibility to thermal stress. This study assessed the variation in thermal tolerance of six seagrass species at both broad latitudinal (c. 500–1000 km) and local scales (c. 25 km). Photosynthesis–temperature curves (15–45°C) were conducted, by measuring oxygen in closed incubation chambers, and thermal optima (Topt) was extracted. We found …

Investigating Climate Change And Nutrient Pollution Effects On Drupella Rugosa Coral Reef Destruction In Koh-Tao, Thailand, Beatrice Canteri

The Plymouth Student Scientist

The introduction and proliferation of invasive species in coral reef ecosystems play a pivotal role as significant contributors to ecological disturbance. These invasive species pose specific threats to the delicate equilibrium of coral reef health by disrupting nutrient cycling, modifying community structure, applying selective pressure on essential coral species, leading to ecosystem degradation. Embarking on an exploration of ecological intricacies, this study focuses on the invasive coral-feeding snail Drupella rugosa in Koh Tao and aims to explore how environmental variables affect its abundance. Although prior research elucidated the impacts of environmental stressors on coral reef degradation, methodological limitations and gaps …

Coastal Marine Heatwaves In The Santa Barbara Channel: Decadal Trends And Ecological Implications, Kit Yu Karen Chan, L. Kui, A. M. Mcdonald, A. L. Ritger, G. E. Hofmann

Biology Faculty Works

Marine heatwaves (MHWs) are of increasing concern due to the emerging ecological and socioeconomic impacts on coastal ecosystems. Leveraging the data of the Santa Barbara Coastal Long-Term Ecological Research project, we analyzed the MHW event metrics observed in the kelp forest ecosystem and across Santa Barbara Channel, CA, USA. Not only was there a significant positive trend in the number of MHWs recorded, their duration and intensity were also increasing over time. MHWs were detected year-round, suggesting that marine organisms have exposure risks regardless of their phenology. Exposure at one life history stage could have a legacy effect on the …

Patterns Of Carbon And Nitrogen Accumulation In Seagrass (Posidonia Oceanica) Meadows Of The Eastern Mediterranean Sea, Eugenia T. Apostolaki, Paul S. Lavery, Victoria Litsi-Mizan, Eduard Serrano, Karina Inostroza, Vasilis Gerakaris, Thanos Dailianis, Julius Glampedakis, Tara Holitzki, Erik Johnson, Miguel A. Mateo, Oscar Serrano

Research outputs 2022 to 2026

The variability in stocks and accumulation rates of organic carbon (Corg), nitrogen (N), and carbonate (CaCO3) was studied in fifteen Posidonia oceanica meadows spread throughout the South Aegean Sea (Greece). In addition, the abiotic and biotic drivers determining the pattern of variability in the accumulation rates were assessed by exploring the influence of sediment characteristics, seagrass traits, and environmental settings. The meadows supported on average (±STDEV) 14.6 ± 5.0 kg Corg m−2, 0.47 ± 0.17 kg N m−2, and 249 ± 210 kg CaCO3 m−2 in the top meter of their sediments, with mean accumulation rates over the last 500 …

Australians Support Multi-Pronged Action To Build Ecosystem Resilience In The Great Barrier Reef, Stewart Lockie, Henry Bartelet, Brent Ritchie, Csilla Demeter, Bruce Taylor, Lintje Sie

Quantitative Methods and Information Technology Faculty Publications

The scale and pace of global environmental change calls for a dramatic upscaling of ecosystem restoration and for actions that build the resilience of ecosystems to future environmental change. This research aimed to quantify public perceptions of threats to the health of the Great Barrier Reef (GBR), Australia, and their support for strategies to address those threats including large-scale restoration and resilience-building actions. We examine how these perceptions change over time and across social cohorts including people living closer to the Reef (n = 2621) and the general Australian population (n = 5825). Respondents were concerned about both …

In Hot Water: Uncertainties In Projecting Marine Heatwaves Impacts On Seagrass Meadows, Paula S. Hatum, Kathryn Mcmahon, Kerrie Mengersen, Jennifer K. Mcwhorter, Paul P.Y. Wu

Research outputs 2022 to 2026

Seagrass ecosystems, vital as primary producer habitats for maintaining high biodiversity and delivering numerous ecosystem services, face increasing threats from climate change, particularly marine heatwaves. This study introduces a pioneering methodology that integrates Dynamic Bayesian Networks of ecosystem resilience with climate projections, aiming to enhance our understanding of seagrass responses to extreme climate events. We developed cutting-edge metrics for measuring shoot density and biomass in terms of population and site extinction, presented as annual ratios relative to their respective baselines. These metrics include associated uncertainties and projected recovery times. This innovative approach was applied in a case study focusing on …

Projected Range Shift Of The Atlantic Surfclam, Spisula Solidissima, And The Ocean Quahog, Arctica Islandica, Under Climate-Induced Benthic Warming: Forecasting Fishery Influence In The Mid-Atlantic Bight Throughout The 21st Century, Molly Mae Spencer

Master's Theses

The Atlantic surfclam, Spisula solidissima, and ocean quahog, Arctica islandica, are biomass dominant bivalve species on the eastern North American continental shelf, both supporting lucrative commercial fisheries in the Mid-Atlantic with a combined value of $53.6 million in ex-vessel revenue per year. Rapid climate change is expected to modify the geographic range of these bivalve populations across the Mid-Atlantic Bight (MAB), suggesting transformative consequences for the surfclam fishery. This study forecasted future distributions of the two species from years 2016 – 2095, based on projected bottom water temperatures and a temperature-dependent population dynamics model, to project subsequent fishery-based indicators …

Relationship Between Marine Heatwaves And Diadema Antillarum Settlement In The Florida Keys, David Ogando Jr.

Theses, Dissertations and Culminating Projects

Ocean warming can have profound impacts on benthic marine invertebrates through direct physiological effects. Yet, the impacts of ocean warming on the long-spined sea urchin (Diadema antillarum), a keystone grazer on western Atlantic and Caribbean coral reefs, has received little attention. In the summer of 2023, the Caribbean basin experienced a strong marine heatwave event with sea temperatures ~1–3°C above average and the warmest on record in southern Florida. An ongoing field settlement sampling program for D. antillarum in the Florida Keys provided an opportunity to examine the correlative relationship between thermal exposure and larval settlement. Thermal exposure was quantified …

Changes In Reef Tourism’S Adaptive Capacity After Severe Climate Disturbances, Henry Bartelet, Michele Barnes, Lalu Bakti, Graeme S. Cumming

Quantitative Methods and Information Technology Faculty Publications

Knowledge about adaptive capacity and its determinants has increased significantly over the last decade. However, most research on adaptive capacity has been static, not considering how adaptive capacity might change over time, particularly after severe disturbances. We studied the adaptive capacity dynamics of Asian-Pacific reef tourism operators affected by coral bleaching and tropical cyclones compared with a control group with non-affected operators. We found that impacts from tropical cyclones were associated with frequent changes in adaptive capacity. Notably, we found a reduction in tangible attributes (assets and flexibility) of adaptive capacity, whereas intangible attributes (agency and social organization) increased. Our …

Wrack Lines Volume 24, Number 1, Spring/Summer 2024, Gract Cajski, Paul Choiniere, Maggie Cozens, Owen Placido, Judy Benson

Wrack Lines

"Natural Effects: Tales of Our Dynamic Environment" is the theme of this issue, with articles about a research project using GoPro cameras on oyster cages; the exploding population of black sea bass in Long Island Sound; three research projects in Connecticut salt marshes; a children's book illustrator and author and her book about kelp farming; and a living shoreline project in Old Saybrook, CT.

A 2,000-Year Record Of Eelgrass (Zostera Marina L.) Colonization Shows Substantial Gains In Blue Carbon Storage And Nutrient Retention, Martin Dahl, Martin Gullström, Irene Bernabeu, Oscar Serrano, Carmen Leiva-Dueñas, Hans W. Linderholm, Maria E. Asplund, Mats Björk, Tinghai Ou, J. Robin Svensson, Elinor Andrén, Thomas Andrén, Sanne Bergman, Sara Braun, Anneli Eklöf, Zilvinas Ežerinskis, Andrius Garbaras, Petter Hällberg, Elin Löfgren, Malin E. Kylander, Pere Masqué, Justina Šapolaitė, Rienk Smittenberg, Miguel A. Mateo

Research outputs 2022 to 2026

Assessing historical environmental conditions linked to habitat colonization is important for understanding long-term resilience and improving conservation and restoration efforts. Such information is lacking for the seagrass Zostera marina, an important foundation species across cold-temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes …

Fauna, Flora, And Land Cover Changes Over The Last Two Decades In The Mobile-Tensaw River Delta, Gabriel De Oliveria, Steven R. Schultze, Guilherme Mataveli

Technical Reports

A technical report documenting ecosystem changes to the Mobile-Tensaw River Delta region due to urban expansion over approximately two decades (2001-2019).