About

Using long-term mark-recapture of the notoriously feisty Florida Softshell (Apalone ferox) we modeled the species growth in four dimensions—carapace length, carapace width, plastron length, and shell height—at Wekiwa Springs, FL, USA. For the first 10 to 15 years of life, male softshells grow longer, wider, and faster than females. At 15 years old, females have caught up and are roughly the same dimensions as males. After this, old females keep growing, mostly in length, maxing out around half a meter long and 18 kilos! Building off previous lab research, we used a Bayesian multivariate von Bertalanffy growth model to handle the individual repeated measures of growth in the mark-recapture time series.

Research topics

• Biology
• Biophysics
• Cell biology
• Biochemistry
• Nanotechnology
• Ecology
• Zoology
• Acoustics
• Geology
• Materials science
• Biomedical engineering
• Fishery
• Oceanography
• Physics
• Evolutionary biology
• Geography

Selected publications

• Data accompanying "Fertilizer enhances production more than mussels in a deteriorating salt marsh"

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-10

  datasetOpen access

  These data accompany the publication of the same name. We performed a two-year manipulative field study in a deteriorating Florida salt marsh dominated by smooth cordgrass (Spartina alterniflora). We examined the interactive effects of ribbed mussel (Geukensia demissa) presence and fertilizer addition on cordgrass production, resistance of cordgrass stems to uprooting, cordgrass regrowth, the abundance of resident fauna, and porewater, leaf tissue, and soil nutrient concentrations. Data used in the manuscript are organized in seven Excel files: 1) cordgrass aboveground biomass, belowground production, and stem density data; 2) cordgrass regrowth data; 3) faunal data; 4) mussel data; 5) nutrient indicator data; 6) cordgrass stem height data; and 7) cordgrass uprooting resistance data. Information describing each dataset can be found in the “Metadata” sheet within each Excel file. This research was funded by the University of Florida Water Institute and the University of Florida School of Forest, Fisheries, and Geomatics Sciences.

  PublisherDOI

• Novel approaches to age validation of Gulf of Alaska groundfishes

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-01

  reportOpen accessSenior author

  Datasets and R code for the Final Report of Novel approaches to age validation of Gulf of Alaska groundfishes to the National Pacific Research Board. Datasets: Datasets are split into two main data types, those from bomb radiocarbon and ageing of otoliths, and those produce from measuring amino acid racemization and d18O stable isotopes. For bomb radiocarbon and ageing of otoliths, there are four files [embargoed for 2 years]: EBS_ref.csv, the East Bering Sea bomb radiocarbon reference curve from Halibut. GOA_ref.csv, the Gulf of Alaska bomb radiocarbon reference curve from Halibut. These dataset contains: Samples: Unique sample ID Source: categorical variable for where the Halibut sample came from region: EBS for East Bering Sea beginlat: latitude of sample beginlon: longitude of sample FL_mm: fork length in mm of the Halibut sample sex: sex of Halibut sample Age_y: age in years of Halibut sample Sample_year: year the Halibut sample was taken Birth_year: the birth year of the Halibut sample Fmodern: fraction modern D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard sigma: measurement error of the D14C signal Sablefish_D14C.csv, aged Sablefish otoliths and their ∆14C signature Sample: unique sample ID Will BY: observed birth year from ageing otolith based on sample date by reader 1, Will Patterson D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard Shortraker_D14C.csv, aged Shortraker Rockfish otoliths and their ∆14C signature Sample: unique sample ID Will BY: observed birth year from ageing otolith based on sample date by reader 1, Will Patterson D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard Yelloweye_D14C.csv, aged Yelloweye Rockfish otoliths and their ∆14C signature Sample: unique sample ID Species: species ID Location: sampling location in Alaska Collection year: year of sampling Will Age: age from otolith ageing by reader 1, Will Patterson R2 Age: age from otolith ageing by reader 2 Will BY: observed birth year from ageing otolith based on sample date by reader 1, Will Patterson R2 BY: observed birth year from ageing otolith based on sample date by reader 2 Lens core D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard For the amino acid racemization and d18O stable isotope data [embargoed for 2 years]: Sablefish_AAR.csv; Shortraker_AAR.csv; Yelloweye_AAR.csv, amino acid racemization and d18O stable isotope data Sample ID: unique sample ID Species: species ID Consensus age y: consensus age from otoliths D/Lasp: ratio of D-form to L-form enantiomers of aspartic acid transformed D/LASP: transformed D:L aspartic acid ratios, ln((1+D:L)/(1-D:L)) lifetime d18O: lifetime signature of the deviation of 18-Oxygen to 16-Oxygen stable isotope ratios lifetime temp C: extrapolated lifetime temperature in Celsius from lifetime d18O lifetime temp F: extrapolated lifetime temperature in Fahrenheit from lifetime d18O GOM_AAR.csv Species: species ID Age y: otolith age transformed D/L: transformed D:L aspartic acid ratios, ln((1+D:L)/(1-D:L)) temp C: estimated temperature from sampling location R code: For the age validation analysis: EBSGOA_ref_run.R This script run a a series of coupled functions and Bayesian B-spline to compare the East Bering Sea and Gulf of Alaska reference series models. EBSexp_Sablefish.R, EBSexp_Shortraker.R These scripts run a coupled function with exponential Bayesian integrated age validation on Sablefish and Shortraker Rockfish for a single reader EBSexp_Yelloweye.R These scripts run a coupled function with exponential Bayesian integrated age validation on Yelloweye Rockfish for both readers and the average of their ages. For lifetime temperature and amino acid racemization: AAR.R, this script runs: species-specific models of amino acid racemization as a function of age a model of amino acid racemization rate as a function of lifetime temperature species-specific models of lifetime temperature as a function of age

  PublisherDOI

• Post-release mortality of red snapper, Lutjanus campechanus, in US Atlantic waters off northeast Florida estimated with three-dimensional acoustic telemetry

  Fisheries Research · 2026-03-12

  article
  PublisherDOI

• Data accompanying "Fertilizer enhances production more than mussels in a deteriorating salt marsh"

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-10

  datasetOpen access

  These data accompany the publication of the same name. We performed a two-year manipulative field study in a deteriorating Florida salt marsh dominated by smooth cordgrass (Spartina alterniflora). We examined the interactive effects of ribbed mussel (Geukensia demissa) presence and fertilizer addition on cordgrass production, resistance of cordgrass stems to uprooting, cordgrass regrowth, the abundance of resident fauna, and porewater, leaf tissue, and soil nutrient concentrations. Data used in the manuscript are organized in seven Excel files: 1) cordgrass aboveground biomass, belowground production, and stem density data; 2) cordgrass regrowth data; 3) faunal data; 4) mussel data; 5) nutrient indicator data; 6) cordgrass stem height data; and 7) cordgrass uprooting resistance data. Information describing each dataset can be found in the “Metadata” sheet within each Excel file. This research was funded by the University of Florida Water Institute and the University of Florida School of Forest, Fisheries, and Geomatics Sciences.

  PublisherDOI

• Novel approaches to age validation of Gulf of Alaska groundfishes

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-01

  reportOpen accessSenior author

  Datasets and R code for the Final Report of Novel approaches to age validation of Gulf of Alaska groundfishes to the National Pacific Research Board. Datasets: Datasets are split into two main data types, those from bomb radiocarbon and ageing of otoliths, and those produce from measuring amino acid racemization and d18O stable isotopes. For bomb radiocarbon and ageing of otoliths, there are four files: EBS_ref.csv, the East Bering Sea bomb radiocarbon reference curve from Halibut. GOA_ref.csv, the Gulf of Alaska bomb radiocarbon reference curve from Halibut. These dataset contains: Samples: Unique sample ID Source: categorical variable for where the Halibut sample came from region: EBS for East Bering Sea beginlat: latitude of sample beginlon: longitude of sample FL_mm: fork length in mm of the Halibut sample sex: sex of Halibut sample Age_y: age in years of Halibut sample Sample_year: year the Halibut sample was taken Birth_year: the birth year of the Halibut sample Fmodern: fraction modern D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard sigma: measurement error of the D14C signal Sablefish_D14C.csv, aged Sablefish otoliths and their ∆14C signature Sample: unique sample ID Will BY: observed birth year from ageing otolith based on sample date by reader 1, Will Patterson D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard Shortraker_D14C.csv, aged Shortraker Rockfish otoliths and their ∆14C signature Sample: unique sample ID Will BY: observed birth year from ageing otolith based on sample date by reader 1, Will Patterson D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard Yelloweye_D14C.csv, aged Yelloweye Rockfish otoliths and their ∆14C signature Sample: unique sample ID Species: species ID Location: sampling location in Alaska Collection year: year of sampling Will Age: age from otolith ageing by reader 1, Will Patterson R2 Age: age from otolith ageing by reader 2 Will BY: observed birth year from ageing otolith based on sample date by reader 1, Will Patterson R2 BY: observed birth year from ageing otolith based on sample date by reader 2 Lens core D14C: deviation of the Carbon 14 to Carbon 12 ratio from a modern standard For the amino acid racemization and d18O stable isotope data: Sablefish_AAR.csv; Shortraker_AAR.csv; Yelloweye_AAR.csv, amino acid racemization and d18O stable isotope data Sample ID: unique sample ID Species: species ID Consensus age y: consensus age from otoliths D/Lasp: ratio of D-form to L-form enantiomers of aspartic acid transformed D/LASP: transformed D:L aspartic acid ratios, ln((1+D:L)/(1-D:L)) lifetime d18O: lifetime signature of the deviation of 18-Oxygen to 16-Oxygen stable isotope ratios lifetime temp C: extrapolated lifetime temperature in Celsius from lifetime d18O lifetime temp F: extrapolated lifetime temperature in Fahrenheit from lifetime d18O GOM_AAR.csv Species: species ID Age y: otolith age transformed D/L: transformed D:L aspartic acid ratios, ln((1+D:L)/(1-D:L)) temp C: estimated temperature from sampling location R code: For the age validation analysis: EBSGOA_ref_run.R This script run a a series of coupled functions and Bayesian B-spline to compare the East Bering Sea and Gulf of Alaska reference series models. EBSexp_Sablefish.R, EBSexp_Shortraker.R These scripts run a coupled function with exponential Bayesian integrated age validation on Sablefish and Shortraker Rockfish for a single reader EBSexp_Yelloweye.R These scripts run a coupled function with exponential Bayesian integrated age validation on Yelloweye Rockfish for both readers and the average of their ages. For lifetime temperature and amino acid racemization: AAR.R, this script runs: species-specific models of amino acid racemization as a function of age a model of amino acid racemization rate as a function of lifetime temperature species-specific models of lifetime temperature as a function of age

  PublisherDOI

• Update to NOAA Technical Memorandum NMFS-PIFSC-101: Incorporating uncertainty in maturation and recent fishery takes into the population-level impacts of western Pacific leatherback sea turtles

  National Oceanic and Atmospheric Administration (NOAA) - NOAA Central Library · 2026-04-22

  articleOpen access1st authorCorresponding

  This technical memorandum update revisits, updates, and modifies the population viability analysis (PVA) of Martin et al. (2020a), the results of Martin et al. (2020b) and Siders et al. (2023) for the Hawaiʻi deep-set pelagic longline fishery (DSLL) interactions with western Pacific leatherback sea turtles. The net result of the changes implemented is a small change between the last assessment, which included data through 2021, and the current assessment.

  PublisherDOI

• Bright nights and dynamic seascape features drive leatherback turtle (Dermochelys coriacea) interactions in an Australian pelagic longline fishery

  Progress In Oceanography · 2026-04-17

  articleOpen access

  • Western boundary current drives highly variable seascapes in east Australian waters. • We used environmental data from Bluelink ReANalysis (BRAN2020) and fisheries data. • Ensemble Random Forests modelled fishery interaction risk with leatherback turtles. • Risk increased around dynamic seascape features and brighter lunar phases. • Foundation for operational tool for dynamic management of wildlife interactions. Marine wildlife bycatch is a persistent and pervasive issue limiting sustainable fisheries management. Key gaps in knowledge include the spatio-temporal dynamics of where fisheries and marine wildlife overlap, and what drives interactions between them. The Critically Endangered Western Pacific subpopulation of leatherback turtles ( Dermochelys coriacea ) migrate and forage along the east coast of Australia, where they interact with a pelagic longline fishery. This region is characterised by a western boundary current system with a highly dynamic seascape, yet little is known about how leatherback turtles use this pelagic habitat or the drivers of fisheries interaction risk. Here, we use Ensemble Random Forests to examine the influence of surface and subsurface conditions derived from outputs of an openly available data-assimilative ocean model, season, and lunar illumination, on fisheries interactions with leatherback turtles. We found the highest risk areas for leatherback interactions were also the most oceanographically dynamic. Persistent links between leatherback turtle interactions and dynamic ocean features, particularly those associated with the East Australian Current, are explored. We hypothesise that turtles are likely using these features to forage and conserve thermal energy. The risk of interaction also increased during brighter periods of the lunar cycle; a finding likely driven by foraging ecology. These findings provide new information of value to industry and managers and a foundation for testing the utility of data-assimilative ocean models as the basis of decision-support tools for bycatch avoidance.

  PublisherDOI

• Fertilizer enhances production more than mussels in a deteriorating salt marsh

  Journal of Applied Ecology · 2026-04-01

  article

  Abstract Coastal ecosystems like salt marshes are exposed to anthropogenic nutrient loading from sources including urban run‐off. Although fertilization often drives declines in marsh below‐ground production, outcomes vary according to marsh health. On the U.S. East Coast, cordgrass ( Spartina alterniflora ) forms an important mutualism with ribbed mussels ( Geukensia demissa ), through which mussels benefit cordgrass by delivering nitrogen, among other mechanisms. Despite the ecological importance of this mutualism, scientists have not rigorously examined the interaction between fertilization and mussel mutualists. To disentangle potential interacting effects of fertilization and mussel presence in marshes, we performed a two‐year manipulative field study in a deteriorating Florida salt marsh, examining vegetative growth, porewater, leaf tissue and soil nutrients, and the abundance of resident fauna. We found that fertilization, regardless of mussel addition, significantly increased above‐ and below‐ground production of short‐form cordgrass (370% and 160% respectively). Mussels in unfertilized plots also enhanced above‐ground biomass, stem heights and stem density but less so than fertilization. We further explored impacts of fertilization on cordgrass by manually uprooting stems, finding that fertilizer—not mussel presence—increased resistance to dislodgment. Lastly, we assessed marsh recovery by removing all above‐ground vegetation and found that fertilization led to 2–3.5x more regrowth. Apparent antagonism between our treatments reduced regrowth in plots with mussels and fertilizer, while mussels improved regrowth in unfertilized plots. Multivariate analyses of nutrient metrics and fauna indicate that, absent mussels, fertilized and unfertilized plots were highly dissimilar. Mussel addition resulted in increased similarity between fertilized and unfertilized plots. Synthesis and applications . Contrary to our predictions, fertilizer addition promoted below‐ground production, while also increasing regrowth and resistance to uprooting. While the impacts of mussel addition appeared minimal relative to those of fertilization, mussel presence tended to reduce the variability of several metrics (stem density, stem height, faunal community), while fertilizer alone increased it (above‐ground biomass, faunal community). Our findings demonstrate that fertilization may help degrading cordgrass marshes overcome growth‐limiting conditions, triggering a positive feedback loop of production. As such, we suggest that strategic, short‐term fertilization may promote survival of degrading marshes while they await large‐scale restoration.

  PublisherDOI

• Age, growth, maturity, and natural mortality of the smalltooth sawfish (Pristis pectinata) in Florida waters

  Fishery Bulletin · 2025-01-01 · 1 citations

  articleOpen access

  Accurate estimates of age, somatic growth, maturity, and natural mortality are essential for effective conservation of endangered species. This study resulted in updated growth data and the first direct assessments of length at maturity and age at maturity for the endangered smalltooth sawfish (Pristis pectinata). A Bayesian approach using the von Bertalanffy growth function was used to combine vertebral band counts, mark-recapture data, and results from increment analysis to estimate somatic growth and to derive age at maturity and natural mortality rates. Smalltooth sawfish grow rapidly in their first 3 years, reaching 235 cm stretch total length (STL), 3.2 times their mean length at birth (73.7 cm STL), before growth slows. Asymptotic length was 446 cm STL for males and 484 cm STL for females, with a Brody growth coefficient of 0.178 year−1 for males and 0.170 year−1 for females. We directly estimated median age at maturity as 6.9 years for males and 7.9 years for females, similar to previous indirect assessments. Constant natural mortality was estimated to be between 0.151 and 0.278 on the basis of life history surrogates. The oldest individual examined in this study was a 30.1-year-old female, confirming that the species exceeds 30 years in the wild. These results are vital for refining population recovery models, and they underscore the need for ongoing monitoring and data collection to support long-term recovery efforts.

  PublisherOA PDFDOI

• Hawai‘i's pelagic longline fishery demonstrates the need to consider multispecies impacts in bluewater time-area closures

  ICES Journal of Marine Science · 2025-07-01

  articleOpen access

  Abstract Cap-based time-area closures can reduce the incidental capture of specific non-target species in fisheries by temporarily closing fishing areas when bycatch exceeds a threshold. The displacement of fishing effort can result in bycatch tradeoffs by increasing interactions with other species or even negate the intended effect of the closure. Here, we assessed the change in bycatch risk for a suite of species of concern resulting from the Southern Exclusion Zone (SEZ), a 343 796 km2 bycatch cap-based time-area closure designed to protect false killer whales from mortality and serious injury in the Hawaiʻi deep-set longline fishery. The SEZ was enacted twice between 2018 and 2020. We found that during the SEZ closures, fishing effort increased along the eastern and southern SEZ border, where species like oceanic whitetip sharks, giant manta rays, and olive ridley sea turtles showed the most concentrated risk, indicating high susceptibility to overlap with displaced effort. Scalloped hammerhead sharks and green and leatherback sea turtles faced moderate risk near heavy fishing, while loggerhead turtles and false killer whales showed diffuse risk. These results highlight that while cap-based closures aim to protect a single species, effective Ecosystem-Based Fisheries Management should consider the entire species portfolio in conservation strategies.

  PublisherOA PDFDOI

Frequent coauthors

• Fabio P. Caltabellotta

  Washington Department of Fish and Wildlife

  14 shared

• Robert N. M. Ahrens

  NOAA National Marine Fisheries Service Pacific Islands Fisheries Science Center

  11 shared

• Edward V. Camp

  University of Florida

  8 shared

• T. Todd Jones

  NOAA National Marine Fisheries Service

  8 shared

• Summer L. Martin

  6 shared

• Robert Ahrens

  NOAA National Marine Fisheries Service

  6 shared

• Heather N. Koopman

  University of North Carolina Wilmington

  5 shared

• Derek W. Chamberlin

  NOAA National Marine Fisheries Service

  5 shared

Education

• Ph.D., Fisheries and Aquatic Sciences

  University of Florida

  2017

• M.Sc., Biology and Marine Biology

  University of North Carolina at Wilmington

  2013

• B.Sc., Biology and Marine Biology

  University of North Carolina at Wilmington

  2011

• B.A., Chemistry

  University of North Carolina at Wilmington

  2011