Biology subjects

Durkin, C. A.

Publications and source records attributed to Durkin, C. A..

3 recordsLinked to original sources

bioRxiv2024

Ocean carbon export can be predicted from ocean color-based phytoplankton communities

Carbon flux to the deep sea can be dictated by surface ocean phytoplankton community composition, but translating surface ocean observations into quantitative predictions of carbon export requires additional consideration of the underlying ecosystem drivers. Here, we used genetic tracers of phytoplankton detected in surface seawater and within sinking particles collected in the mesopelagic ocean to identify mechanistic links between surface communities and carbon export in the North Pacific and North Atlantic Oceans. Phytoplankton 18S rRNA sequences were sampled over a one-month period in surface seawater and within bulk-collected and individually-isolated sinking particles using mesopelagic sediment traps (100-500m). Nearly all phytoplankton amplicon sequence variants (ASVs) exported from the surface were packaged in large (>300 {micro}m) particles. Individually, these particles contained only a few distinct phytoplankton ASVs, but collectively, large particles transported about half of the surface taxonomic diversity into the mesopelagic. The relative sequence abundances of the surface community detected within particles were quantitatively related to measured POC fluxes: a linear model based on the relative sequence abundance of just two pigment-based phytoplankton taxa, diatoms and photosynthetic Hacrobia, was predictive of POC flux magnitude. These two taxa were also enriched within the ecologically-distinct particle classes that had the greatest influence on carbon export magnitude. As global, hyperspectral ocean color satellites begin to quantify these taxonomic groups in the surface ocean, the relationship of these taxa to carbon fluxes demonstrated here may help generate more accurate global estimates of export.

ecology↗

bioRxiv2024

A computer vision-based approach for estimating carbon fluxes from sinking particles in the ocean

The gravitational settling of organic particles in the ocean drives long term sequestration of carbon from surface waters to the deep ocean. Quantifying the magnitude of carbon sequestration flux at high spatiotemporal resolution is critical for monitoring the oceans ability to sequester carbon as ecological conditions change. Here, we propose a computer vision-based method for classifying images of sinking marine particles and using allometric relationships to estimate the amount of carbon that the particles transport to the deep ocean. We show that our method reduces the amount of time required by a human image annotator by at least 90% while producing ecologically- informed estimates of carbon flux that are comparable to estimates based on purely human review and chemical bulk carbon measurements. This method utilizes a human-in-the-loop domain adaptation approach to leverage images collected from previous sampling campaigns in classifying images from novel campaigns in the future. If used in conjunction with autonomous imaging platforms deployed throughout the worlds oceans, this method has the potential to provide estimates of carbon sequestration fluxes at high spatiotemporal resolution while facilitating an understanding of the ecological pathways that are most important in driving these fluxes.

ecology↗

bioRxiv2021

A visual tour of carbon export by sinking particles

To better quantify the oceans biological carbon pump, we resolved the diversity of sinking particles that transport carbon into the oceans interior, their contribution to carbon export, and their attenuation with depth. Sinking particles collected in sediment trap gel layers from 4 distinct ocean ecosystems were imaged, measured, and classified. The size and identity of particles was used to model their contribution to particulate organic carbon (POC) flux. Measured POC fluxes were reasonably predicted by particle images. Nine particle types were identified, and most of the compositional variability was driven by the relative contribution of aggregates, long cylindrical fecal pellets, and salp fecal pellets. While particle composition varied across locations and seasons, the entire range of compositions was measured at a single well-observed location in the subarctic North Pacific over 1 month, across 500 m of depth. The magnitude of POC flux was not consistently associated with a dominant particle class, but particle classes did influence flux attenuation. Long fecal pellets attenuated most rapidly with depth whereas certain other classes attenuated little or not at all with depth. Small particles (<100 m) consistently contributed [~]5% to total POC flux in samples with higher magnitude fluxes. The relative importance of these small particle classes (spherical mini pellets, short oval fecal pellets, and dense detritus) increased in low flux environments (up to 46% of total POC flux). Imaging approaches that resolve large variations in particle composition across ocean basins, depth, and time will help to better parameterize biological carbon pump models.

ecology↗