Todd Z Osborne | University of Florida (original) (raw)

Papers by Todd Z Osborne

Journal of the American Society for Mass Spectrometry

Journal of Marine Science and Engineering

Hurricanes have the ability to export uncharacteristically large amounts of nutrients from terres... more Hurricanes have the ability to export uncharacteristically large amounts of nutrients from terrestrial systems into riverine and estuarine networks, altering rates of ecosystem metabolism throughout the aquatic continuum. In order to explore these impacts and compare these values to common precipitation events, water quality and chemistry data from the National Estuarine Research Reserve’s System Wide Monitoring Program (NERR-SWMP) were combined with discharge data from the United States Geological Survey (USGS) to calculate biogeochemical export from a Florida coastal blackwater river. This analysis was focused on the years 2016–2020, when Hurricanes Matthew, Irma, and Dorian impacted the landscape of Florida’s Atlantic coast. Hurricane Irma, the only hurricane to occur after especially wet summer conditions, dwarfed the other two hurricanes in the export of dissolved organic carbon (DOC), with an increase from <5 kg DOC day−1 to approximately 250 kg DOC day−1. Soluble reactive ...

Journal of Environmental Management, 2022

Mangroves provide critical ecosystems services, contributing an estimated 42 billion US dollars t... more Mangroves provide critical ecosystems services, contributing an estimated 42 billion US dollars to global fisheries, storing 25.5 million tons of carbon per year, and providing flood protection to over 15 million people annually. Yet, they are increasingly threatened by factors ranging from local resource exploitation to global climate change, with an estimated 35% of mangrove forests lost in the past two decades. These threats are difficult to manage due to the intrinsic characteristics of mangrove systems and their provisioning services, and their transboundary and pan-global nature. Due to their unique intertidal ecological niche, mangroves are often treated as a "common pool resource" within national legal frameworks, making them particularly susceptible to exploitation. Moreover, they form ecological connections through numerous biotic and abiotic processes that cross political boundaries. Because of these qualities a cross-scale nested framework of international, regional, and local coordination is necessary to successfully sustain mangrove ecosystems and their valuable services. Although coordination across the geopolitical spectrum is often cited as a need for effective management of common resources such as mangroves, there has been no formal analysis of mangrove multiscale governance. In this paper we address this gap by providing a comprehensive analysis of interactions between and within international, regional, and local mangrove management regimes and examine the challenges and opportunities such multiscale governance frameworks present. We highlight Costa Rica as a case study to demonstrate the universal relevance and potential of multi-scale governance and explore its downscale potential. Using Elinor Ostrom's principles for self-governance of the commons as our touchstone, we identify where improvements to the status quo could be implemented to increase its effectiveness of the current frameworks to meet the ongoing challenge of managing mangrove-derived resources and services in the face of a changing climate and human needs.

Mercury and the Everglades. A Synthesis and Model for Complex Ecosystem Restoration, 2019

Nutrient enrichment—particularly with respect to phosphorus—has long been a major concern in the ... more Nutrient enrichment—particularly with respect to phosphorus—has long been a major concern in the Everglades (see Chap. 2, Volume I). This perturbation is of keen interest with respect to the Everglades mercury (Hg) problem because the biogeochemical cycling of Hg in aquatic ecosystems is intrinsically linked to trophic state through multiple pathways, including the effects of nutrient status on food web structure and dynamics, in situ particle production, and redox dynamics in surficial sediments (see Fig. 1.1, Chap. 1, this volume). As a result, decision makers charged with the responsibility of restoring the Everglades must also consider the resultant impacts of management strategies on not just trophic state dynamics, but also the linked effects of those strategies on Hg biogeochemical cycling and trophic transfer. This chapter thus reviews phosphorus enrichment in the Everglades and its effects on Hg biogeochemical cycling, including its effects on methyl mercury production related to perturbations in redox dynamics in particular.

In the State of Florida, mangrove trees are protected by the 1996 Mangrove Trimming and Preservat... more In the State of Florida, mangrove trees are protected by the 1996 Mangrove Trimming and Preservation Act. The Act states that most trimming of mangroves must be permitted, must adhere to ANSI A300 pruning standards, and must be overseen by qualified mangrove trimmers. ANSI A300 are the generally accepted industry standards for tree care practices developed by the Tree Care Industry Association and written by a committee called the Accredited Standards Committee (ASC) A300. To date, a quantitative analysis of mangrove stress reactions to regulated trimming techniques has not been performed. The goal of this research was to monitor and assess health, structure, and growth of black mangroves (Avicennia germinans) when exposed to repeated trimming as described by Florida Administrative Code. Physiological indicators of tree stress, including chlorophyll content, leaf water pressure, and the formation of wound wood, were recorded for trees receiving one of two ANSI compliant trimming techniques: top trims and window trims. Indicators for trimmed trees were compared to measurements taken from unpruned trees, as well as abiotic stressors such as hurricane damage, and soil accretion. The data suggest proper cut location, trimming aspect ratio, and total biomass removal < 30% in a 12 month period resulted in no significant reduction in chlorophyll production under normal growing conditions. However, chlorophyll data analysis did indicate 24 that trimmed trees may have experienced more stress from hurricanes than untrimmed trees. Soil 25 accretion greater than mangrove pneumatophore level caused total plant necrosis. Regulated mangrove trimming does not appear to reduce the health of A. germinans during normal growing 27 conditions but trimmed trees do experience more stress than untrimmed trees during hurricanes. 28

Comparing cores between coasts Agenda Carbon sequestration in northern Florida wetlands Discussio... more Comparing cores between coasts Agenda Carbon sequestration in northern Florida wetlands Discussions of the top portion of cores and entire cores Study site and proxies What are the cores telling us so far?

1 University of Florida, Soil and Water Sciences 7 2199 South Rock Rd, Ft. Pierce, FL 34945 8 ORC... more 1 University of Florida, Soil and Water Sciences 7 2199 South Rock Rd, Ft. Pierce, FL 34945 8 ORCID ID: 0000-0002-7617-1354 9 *Corresponding Author: pjulian@ufl.edu 10 11 2 Marine Laboratory, Sanibel Captiva Conservation Foundation, Sanibel, FL 33957 12 Email: emilbran@sccf.org 13 14 3 University of Florida, Soil and Water Sciences, Gainesville, FL 32611 15 4 University of Florida, Whitney Laboratory for Marine Bioscience, St Augustine, FL 32080 16 Email: osbornet@ufl.edu 17 18

Frontiers in Marine Science, 2020

Pollution from anthropogenic marine debris, particularly buoyant plastics, is ubiquitous across m... more Pollution from anthropogenic marine debris, particularly buoyant plastics, is ubiquitous across marine ecosystems. Due to the persistent nature of plastics in the environment, their buoyancy characteristics, degradation dynamics, and ability to mimic the behavior of natural prey, there exists significant opportunity for marine organisms to ingest these man-made materials. In this study we examined gastrointestinal (GI) tracts of 42 post-hatchling loggerhead (Caretta caretta) sea turtles stranded in Northeast Florida. Necropsies revealed abundant numbers of plastic fragments ranging from 0.36 to 12.39 mm in size (length), recovered from the GI tracts of 39 of the 42 animals (92.86%), with GI burdens ranging from 0 to 287 fragments with a mass of up to 0.33 g per turtle. Post-hatchlings weighed from 16.0 to 47.59 g yielding a plastic to body weight percentage of up to 1.23%. Several types of plastic fragments were isolated, but hard fragments and sheet plastic were the most common type, while the dominant frequency of fragment color was white. Fragment size and abundance mixed with natural gut contents suggests significant negative health consequences from ingestion in animals at this life stage. Gaining greater insight into the prevalence of plastic ingestion, the types of plastic and the physiological effects of plastic consumption by multiple life-stages of sea turtles will aid the prioritization of mitigation efforts for the growing marine debris problem. This report demonstrates that plastic ingestion is a critical issue for marine turtles from the earliest stages of life.

Diversity, 2019

Decreasing frequency of freeze events due to climate change is enabling the poleward range expans... more Decreasing frequency of freeze events due to climate change is enabling the poleward range expansion of mangroves. As these tropical trees expand poleward, they are replacing herbaceous saltmarsh vegetation. Mangroves and saltmarsh vegetation are ecosystem engineers that are typically viewed as having similar ecosystem functions. However, few studies have investigated whether predation regimes, community structure, and ecosystem functions are shifting at the saltmarsh-mangrove ecotone. In this study, we manipulated predator access to marsh and mangrove creekside habitats to test their role in mediating vegetation and invertebrate structure and stability in a two-year experiment. We also conducted a survey to evaluate how shifting vegetation is modifying structural complexity, invertebrate communities, and ecosystem functioning at the ecotone. Excluding larger (> 2 cm diameter) predators did not affect vegetation or invertebrate structure or stability in either saltmarsh or mangro...

Oikos, 2019

Detrital traits affect substitutability of a range-expanding foundation species across latitude.-... more Detrital traits affect substitutability of a range-expanding foundation species across latitude.-Oikos

Current Biology, 2019

Highlights d Experimental removal of salt marsh vegetation enhances lateral erosion d Belowground... more Highlights d Experimental removal of salt marsh vegetation enhances lateral erosion d Belowground biomass was the plant trait responsible for resisting erosion d Meta-analysis shows that plant die-off generally hastens erosion of salt marshes d Findings support a coastal protection paradigm that incorporates coastal wetlands

Oecologia, 2018

Interactions with resident species can affect the rate that expanding species invade novel areas.... more Interactions with resident species can affect the rate that expanding species invade novel areas. These interactions can be antagonistic (biotic resistance), where resident species hinder invasive establishment, or facilitative (biotic assistance), where residents promote invasive establishment. The predominance of resistance or assistance could vary with the abiotic context. We examined how the effects of a resident ecosystem engineer interact with abiotic stress to resist or assist the establishment of an expanding competitor. In Florida salt marshes, native cordgrass, Spartina alterniflora, is an influential ecosystem engineer that, when dead, exerts a legacy effect by forming persistent wrack patches. We examined how the legacy effect of Spartina wrack varies with spatial context and abiotic conditions to influence establishment of the northward-expanding black mangrove, Avicennia germinans. Field surveys documented that Spartina wrack and Avicennia propagules co-occur in the hi...

Soil Science Society of America Journal, 2016

Core Ideas Surface water sulfate has been implicated in influencing Hg cycling and methylation, t... more Core Ideas Surface water sulfate has been implicated in influencing Hg cycling and methylation, this relationship is tenuous at best therefore other variables and biogeochemical cycles could be involved with Hg methylation dynamics. While thought of as a minor biogeochemical constituent, Fe is involved several biogeochemical interactions including the regulation of surface water sulfate concentrations by producing iron minerals. The results of this study suggest that dissolved organic C supply has the ability to regulate dissimilatory sulfate reduction, rather than sulfate supply within the Everglades marsh. Elevated sulfate (SO42−) concentrations have been implicated in affecting Hg cycling and methylation within the Everglades, leading to environmental concerns regarding methyl‐Hg (MeHg) accumulation in wildlife. The interaction of S and Hg cycles is not fully understood in freshwater wetlands, and factors regulating these elemental cycles are warranted. Iron has been demonstrated...

Environmental Monitoring and Assessment, 2016

High-resolution diffuse reflectance spectra in the visible and near-infrared wavelengths were use... more High-resolution diffuse reflectance spectra in the visible and near-infrared wavelengths were used to predict chemical properties of sediment samples obtained from Lake Okeechobee (FL, USA). Chemometric models yielded highly effective prediction (relative percent difference (RPD) = SD/RMSE >2) for some sediment properties including total magnesium (Mg), total calcium (Ca), total nitrogen (TN), total carbon (TC), and organic matter content (loss on ignition (LOI)). Predictions for iron (Fe), aluminum (Al), and various forms of phosphorus (total P (TP), HCl-extractable P (HCl-P), and KCl-extractable P (KCl-P)) were also sufficiently accurate (RPD > 1.5) to be considered useful; predictions for other P fractions as well as all pore water properties were poor. Notably, scanning wet sediments resulted in only a 7 % decline in RPD scores. Moreover, interpolation maps based on values predicted from wet sediment spectra captured the same spatial patterns for Ca, Mg, TC, TN, and TP as maps derived directly from wet chemistry, suggesting that field scanning of perpetually saturated sediments may be a viable option for expediting sample analysis and greatly reducing mapping costs. Indeed, the accuracy of spectral model predictions compared favorably with the accuracy of kriging model predictions derived from wet chemistry observations suggesting that, for some analytes, higher density spatial sampling enabled by use of field spectroscopy could increase the geographic accuracy of monitoring for changes in lake sediment chemical properties.