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Open Access Publications from the University of California

Scholarly Works (3 results)

  • Article
Coastal Environmental Quality Initiative (2004)

The few remaining coastal wetlands in California are heavily impacted by development, pollution, and eutrophication. Habitat restoration is an increasingly important method for preserving wetland species, but whether reestablishment of plant infrastructure results in recovery of habitat functions remains unknown. I propose to use an experimental approach to investigate the functional recovery of wetlands. Specifically, I will examine the effects of top-down (predation) and bottom-up (food availability) forces on a common gastropod (Cerithidea californica) in southern California coastal wetlands.

This study will consist of three series of experiments performed in natural and restored wetland sites. First, I will investigate the effects of bottom up forces on C. californica abundance, growth, and reproductive output. In caged mudflat enclosures I will alter food availability (by increasing benthic microalgal density through nutrient addition) and snail abundance. I will repeat this experiment seasonally, as the nature of the snail microalgae interaction is likely to change through the year. Second, I will use exclosure cages to examine the top down effects of predation by shorebirds and crabs on lower trophic levels, particularly on C. californica juveniles. These experiments will be timed to correspond with seasonal peaks in predator abundance. Third, based on the results of the previous studies, I will manipulate both food availability and predation to evaluate the combined effects of top down and bottom up forces on C. californica. This synthesis study will simulate trophic interactions that occur in a wetland community, and will enable functional comparisons between natural and restored wetlands.

This unique experimental field approach will allow direct comparison between natural and restored sites, providing valuable insight into whether restoration projects that nominally fill mitigation criteria are truly functioning wetlands. This understanding will contribute to the development of mitigation goals that include functional criteria and will allow functional assessment of restoration success.

    Cover page: Reestablishment of trophic interactions in restored coastal wetlands: the relative importance of top-down and bottom-up forces in structuring Cerithidea californica (Gastropoda) abundance
    • Article
    • Peer Reviewed
    UC Berkeley Previously Published Works (2023)
    UNLABELLED: Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C. Sampling approaches range in their representation of wetland C from short to long timeframes and local to landscape spatial scales. This review summarizes common and cutting-edge methodological approaches for quantifying wetland C pools and fluxes. We first define each of the major C pools and fluxes and provide rationale for their importance to wetland C dynamics. For each approach, we clarify what component of wetland C is measured and its spatial and temporal representativeness and constraints. We describe practical considerations for each approach, such as where and when an approach is typically used, who can conduct the measurements (expertise, training requirements), and how approaches are conducted, including considerations on equipment complexity and costs. Finally, we review key covariates and ancillary measurements that enhance the interpretation of findings and facilitate model development. The protocols that we describe to measure soil, water, vegetation, and gases are also relevant for related disciplines such as ecology. Improved quality and consistency of data collection and reporting across studies will help reduce global uncertainties and develop management strategies to use wetlands as nature-based climate solutions. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13157-023-01722-2.
      Cover page: Practical Guide to Measuring Wetland Carbon Pools and Fluxes.
      • Article
      • Peer Reviewed
      UC Santa Cruz Previously Published Works (2023)
      The organic carbon (Corg) stored in seagrass meadows is globally significant and could be relevant in strategies to mitigate increasing CO2 concentration in the atmosphere. Most of that stored Corg is in the soils that underlie the seagrasses. We explored how seagrass and soil characteristics vary among seagrass meadows across the geographic range of turtlegrass (Thalassia testudinum) with a goal of illuminating the processes controlling soil organic carbon (Corg) storage spanning 23° of latitude. Seagrass abundance (percent cover, biomass, and canopy height) varied by over an order of magnitude across sites, and we found high variability in soil characteristics, with Corg ranging from 0.08 to 12.59% dry weight. Seagrass abundance was a good predictor of the Corg stocks in surficial soils, and the relative importance of seagrass-derived soil Corg increased as abundance increased. These relationships suggest that first-order estimates of surficial soil Corg stocks can be made by measuring seagrass abundance and applying a linear transfer function. The relative availability of the nutrients N and P to support plant growth was also correlated with soil Corg stocks. Stocks were lower at N-limited sites than at P-limited ones, but the importance of seagrass-derived organic matter to soil Corg stocks was not a function of nutrient limitation status. This finding seemed at odds with our observation that labile standard substrates decomposed more slowly at N-limited than at P-limited sites, since even though decomposition rates were 55% lower at N-limited sites, less Corg was accumulating in the soils. The dependence of Corg stocks and decomposition rates on nutrient availability suggests that eutrophication is likely to exert a strong influence on carbon storage in seagrass meadows.
        Cover page: Seagrass Abundance Predicts Surficial Soil Organic Carbon Stocks Across the Range of Thalassia testudinum in the Western North AtlanticCreative Commons 'BY' version 4.0 license
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