Mapping the Risk of High Chlorophyll and HAB events in the Chesapeake Bay
College
College of Sciences
Department
Ocean and Earth Sciences
Graduate Level
Master’s
Graduate Program/Concentration
Oceanography
Presentation Type
Poster Presentation
Abstract
Harmful algal blooms (HABs) are characterized as an event where photosynthetic algae grows at an unsustainable rate within the water which can result in mass mortalities of marine organisms, oxygen depleted zones, and an overall degradation of aquatic habitats. With HABs occurring annually in the Chesapeake Bay it is of utmost importance to mitigate their negative effects. Current monitoring programs mainly rely on in-situ collection which is both spatially and temporally scarce and allows for some high chlorophyll and HAB events to go undetected. Due to this limitation of in-situ monitoring, the use of satellites has become integral in detecting blooms since it has the ability to collect almost real time, large-scale, and long-term monitoring of identified hotspots. This project analyzed data collected from 2021-2023 and the area of interest is the Rappahannock River due to it experiencing annual blooms and it being frequently sampled for water quality data via ship cruises and continuous monitoring stations. PlanetScope satellite imagery was chosen due to its daily repeat frequency, high spatial resolution (3 meters) and 8 band spectral characteristics. Chlorophyll concentrations were retrieved from all clear sky images using the Normalized Difference Chlorophyll Index (NDCI, red edge and NIR band ratio) and then transformed to chlorophyll using an algorithm developed for optically complex waters. The satellite and in situ timeseries of HAB presence and density are being compared to evaluate their agreement in detection. Ultimately, the successful implementation of this work will allow for a more targeted and augmented forecasting system for the Chesapeake Bay which is important due to climate change possibly giving rise to more frequent and intensified blooms.
Keywords
Harmful algal blooms, Remote sensing, Chlorophyll, Chesapeake Bay
Mapping the Risk of High Chlorophyll and HAB events in the Chesapeake Bay
Harmful algal blooms (HABs) are characterized as an event where photosynthetic algae grows at an unsustainable rate within the water which can result in mass mortalities of marine organisms, oxygen depleted zones, and an overall degradation of aquatic habitats. With HABs occurring annually in the Chesapeake Bay it is of utmost importance to mitigate their negative effects. Current monitoring programs mainly rely on in-situ collection which is both spatially and temporally scarce and allows for some high chlorophyll and HAB events to go undetected. Due to this limitation of in-situ monitoring, the use of satellites has become integral in detecting blooms since it has the ability to collect almost real time, large-scale, and long-term monitoring of identified hotspots. This project analyzed data collected from 2021-2023 and the area of interest is the Rappahannock River due to it experiencing annual blooms and it being frequently sampled for water quality data via ship cruises and continuous monitoring stations. PlanetScope satellite imagery was chosen due to its daily repeat frequency, high spatial resolution (3 meters) and 8 band spectral characteristics. Chlorophyll concentrations were retrieved from all clear sky images using the Normalized Difference Chlorophyll Index (NDCI, red edge and NIR band ratio) and then transformed to chlorophyll using an algorithm developed for optically complex waters. The satellite and in situ timeseries of HAB presence and density are being compared to evaluate their agreement in detection. Ultimately, the successful implementation of this work will allow for a more targeted and augmented forecasting system for the Chesapeake Bay which is important due to climate change possibly giving rise to more frequent and intensified blooms.