Coastal and Marine Ecology Lab

Department of Environmental Sciences

University of Virginia


Home        Karen McGlathery        Research        The Lab Group        Publications        Photos

Coastal and Marine Ecology Lab

Department of Environmental Sciences

University of Virginia


Home        Karen McGlathery        Research        The Lab Group        Publications        Photos

 

Current Graduate Students

LUKE COLE

Degree: Ph.D.

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curriculum vitae


The coastal lagoons of Virginia underwent a dramatic state change in the 1930’s from a seagrass-vegetated state to one dominated by benthic algae. The wholesale loss of seagrass (eelgrass, Zostera marina) was caused by a severe storm that affected populations already weakened by disease. After the discovery of small, natural patches of seagrasses, large-scale restoration by seeding is now underway. This gives us an unprecedented opportunity to determine experimentally the ecosystem-level effects of a rapid state change back to the original seagrass-vegetated state. Seagrasses provide many critical ecosystem services in the coastal zone including acting as a filter for watershed nutrients, stabilizing the seafloor, and providing an important habitat and food source for fishes and invertebrates, many of which are of commercial value. This proposed study will determine the effects of the return of this ‘foundation species’ on nutrient dynamics in the coastal lagoons of the Virginia Coast Reserve using a chronosequence of different aged seagrass meadows. Specifically, I will compare nitrogen cycling processes that are influenced by seagrasses (e.g., denitrification, nitrogen fixation, nitrogen mineralization, dissimilatory nitrate reduction to ammonium) and nitrogen retention within plant tissue and sediments in newly restored meadows (1-2 years old), intermediate aged meadows (4-6 years old), and mature, established meadows (>10 years old). These parameters will then be compared to adjacent ‘bare’ areas where benthic algae occur. The results of this study will both assess the restoration progress based on the biogeochemical similarities of the restored and mature eelgrass meadows, and the ecosystem-level consequences of the return of the key ‘ecological engineer’ in these coastal lagoons. The long and short of it is that seagrasses rock my boat.


Advisor: Karen McGlathery

Dana Gulbransen

Degree: Ph.D.

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I will be investigating how widespread the invasive macroalgae, Gracilaria vermiculophylla, is in lagoons surrounding the Delmarva Peninsula on the Eastern Shore of Virginia. Once I have determined how prevalent this invasive alga is, I will determine how it is affecting nitrogen transfers between salt marsh, mudflat, and seagrass communities in this region. As the final facet of this research I will determine how the presence of Gracilaria vermiculophylla affects biodiversity of epifauna in the lagoons. I will use this nitrogen and biodiversity data to determine if Gracilaria vermiculophylla is helping or hurting the salt marsh, mudflat, and seagrass communities and if there is a threshold to this relationship.


Advisor: Karen McGlathery


Kim Holzer

Degree: Ph.D.

email

curriculum vitae


I am broadly interested in the interaction between consumers (top-down forces) and nutrients (bottom-up forces) on the structure and function of marine plant communities. Understanding the linkages between natural (herbivory) and human dynamics (nutrient loading and fishery practices) on seagrass ecosystems is one priority of my research. Currently, I am most excited about how grazers with different feeding strategies may mediate nutrient pollution in coastal waterways. For my dissertation project, you can find me playing/working in Bermuda seagrass meadows. Other curiosities of mine involve the concept of 'gardening' by marine animals, including crop cultivation (fertilization and pruning) and preference. Educational outreach and science-based conservation decisions are important to me. Using photography to record and communicate scientific data is another one of my growing interests.


Advisor: Karen McGlathery


Matthew Long

Degree: Ph.D.

email

curriculum vitae


Project: Carbonate sediment dissolution has received much attention as it can be a significant sink for phosphorus and its products can be very important to the success of reef-building corals and calcareous algae. The role of plants and animals in examining the equilibrium state of carbonate dissolution can help to elucidate why dissolution occurs at enhanced rates in the presence of organisms, as well as how organisms can act to increase essential nutrients for uptake. I am currently finishing my master’s research that involved the investigation of organic acid exudates from the seagrass Thalassia testudinum in the Florida Bay estuary, Florida. The data show increases in phosphate, organic acids, and dissolution surrounding root tips, suggesting that the seagrass can influence a small area around the root tips to increase available nutrients, in this case, especially phosphate.


My doctoral research will involve another component of carbonate dissolution, investigated using the eddy correlation technique. The application of eddy correlation in aquatic environments is a fairly new technique, as fast-responding sensors and electronics have only recently been available. The research will involve the determination of Ca2+ fluxes over reef structures to determine the uptake of Ca2+ by corals, and ultimately their growth. These fluxes combined with O2 fluxes can explain total ecosystem productivity and how it relates to coral growth and health, and other important factors such as bleaching, sea level rise, and temperature increases. The application of this system over seagrass-vegetated, bare, and coral sediments/substrates can help to elucidate current discrepancies in sediment dissolution equilibria. The development of eddy-correlation Ca2+ instrumentation will not only help to answer many important carbonate biogeochemical questions but will also provide an excellent tool for further application and study


Advisors: Peter Berg and Jay Zieman

Sean McLoughlin

Degree: M.S.

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Project: I am interested in studying oceanography and coastal processes, especially salt marsh and beach geomorphology and hydrology. I am working on a research project with Karen and Pat, looking at salt marsh erosion and accretion on the Eastern Shore of Virginia.


Advisors: Karen McGlathery and Pat Wiberg

Meredith Ferdie Muth

Degree: Ph.D.

email

curriculum vitae


Dissertation Project: Disturbance, gap recovery and patch dynamics in species-rich intertidal seagrass communities


My research is on disturbance, recovery and the associated patch dynamics within mixed-species intertidal seagrass communities using a combination of descriptive studies, field manipulations, spatial analyses and modeling. Component I investigates patterns of disturbance from a landscape perspective using satellite imagery and field surveys. Component II examines gap recovery following different small-scale disturbances (sediment burial, excavation, nutrient enrichment) using a two-year field experiment at three sites along a tidal gradient. Component III assesses the species-specific ability of seagrass to colonize existing gaps with different sediment conditions using a one-year field experiment. Component IV attempts to predict seagrass recovery by linking plant-level processes (II, III) with landscape patterns (I) using simple spatially explicit landscape models. This research is being conducted on Inhaca Island, Mozambique, Africa. Inhaca is an ideal locale for seagrass studies because it contains high species diversity (nine species), extensive intertidal and subtidal habitats, and relatively little human impact. Project deliverables include detailed data on lesser studied Indo Pacific, a comparison of disturbance types in different seagrass assemblages along a tidal gradient, the linkage of seagrass disturbance dynamics at the plant and landscape scale, and empirical data required for larger modeling and conceptualizing efforts.


Advisors: Karen McGlathery and Jay Zieman

Laura K Reynolds

Degree: Ph.D.

email

curriculum vitae


Project: My broad interests lie in how human activity alters the marine environment. My dissertation research will focus on genetic diversity of eelgrass (Zostera marina) meadows on the eastern shore of Virginia. Because of a large-scale seagrass die-back, Chesapeake Bay and surrounding coastal bays have been a hot spot for restoration attempts. Restoration generally reduces genetic diversity since transplants are taken from a very small area and many plants do not survive. Humans can also indirectly reduce genetic diversity by means of over-fishing. When fish predators are reduced, invertebrate populations will likely increase. Some invertebrates act as seed predators on seagrasses, and thus their increased population will decrease seagrass sexual reproductive success and potentially decrease genetic diversity. Reductions in genetic diversity are attributed to reduced population growth, reduced individual fitness, and maybe reduced long-term persistence of eelgrass meadows.

My research will involve documenting the genetic diversity of eelgrass beds in the Chesapeake Bay and surrounding coastal bays, including both natural and restored beds. I will conduct a restoration experiment, planting plots with different genetic diversities. I will monitor the survival, morphology, expansion though clonal and sexual reproduction, faunal colonization, and a nitrogen retention of these experimental plots under stressed and unstressed conditions to better understand the role of genetic diversity in ecosystem function. Further, feeding experiments with local invertebrates will determine their role in shaping the genetic diversity of the ecosystem by consuming seeds.



Advisors: Karen McGlathery and Jay Zieman