Find relationships between PACE satellite data and cetacean distribution in the Mid-Atlantic Bight
Folder Structure
contributor_foldersThis is a staging area where our team members practiced!final_notebooksOur final notebook for the time spent on Fish-PACE is heredataThese were datasets that we used, or downloaded
NEFSC Marine Mammals and MOANA: Linking PACE Phytoplankton Community Data to Cetacean Distribution
Using NASA PACE satellite data (MOANA phytoplankton products) to characterize the ecological niches of cetacean species observed during NEFSC Mid-Atlantic offshore surveys.
- Initial idea: Explore whether PACE-derived phytoplankton community composition (prokaryote abundances) can reveal habitat partitioning among co-occurring cetacean species better than traditional chlorophyll-a alone
- Slack channel: fp25_proj_megafauna
| Name | Role |
|---|---|
| Liz Ferguson | Project Facilitator |
| Ana Vaz | Participant |
| James King | Participant |
Traditional cetacean habitat models rely on physical oceanographic variables (SST, depth, chlorophyll-a) that may not capture fine-scale ecological differences between species. NASA's PACE satellite provides novel phytoplankton community composition data through the MOANA product (L4M), resolving Synechococcus, Prochlorococcus, and picoeukaryote abundances at 4 km / 8-day resolution. These prokaryote groups represent different trophic and oceanographic regimes, and may better characterize the prey environments of cetaceans with distinct foraging ecologies.
- Extract and visualize PACE MOANA phytoplankton data for the Mid-Atlantic Bight study area (35.5–41°N, 71.5–77°W)
- Match MOANA data (plus chlorophyll-a, SST, carbon, and bathymetry) to georeferenced cetacean observation records from NEFSC offshore surveys
- Characterize and compare environmental niches across species using statistical tests, niche overlap analysis, PCA, and hierarchical clustering
- Determine whether PACE prokaryote community data reveals habitat partitioning not visible in traditional productivity metrics
| Dataset | Source | Description |
|---|---|---|
| NEFSC Mid-Atlantic Cetacean Survey | OBIS / SEAMAP (dataset 2368) | Georeferenced sightings of cetaceans with group size, Dec 28–Mar 28 |
| PACE OCI MOANA L4M (8-day, 4 km) | NASA Earthdata (PACE_OCI_L4M_MOANA) |
Synechococcus, Prochlorococcus, and picoeukaryote cell concentrations |
| PACE OCI Chlorophyll-a | NASA Earthdata | Chlorophyll-a concentration (mg m⁻³) |
| PACE OCI Particulate Organic Carbon | NASA Earthdata | Phytoplankton carbon (mg m⁻³) |
| PACE OCI Sea Surface Temperature | NASA Earthdata | SST (°C) |
| GEBCO 2025 Bathymetry | GEBCO | 15-arc-second gridded elevation/depth |
| NEFSC Bathymetric Contours | NEFSC | Shapefiles for 50, 100, 200, 500, 1000, 2000 m isobaths |
Species analyzed: Fin whale, Humpback whale, Common minke whale, Sperm whale, North Atlantic right whale, Blue whale, Beaked whales (full dataset); primary niche analyses focused on the four species with the largest sample sizes (Fin, Humpback, Sperm, Common minke).
Section 1 – MOANA Visualization and Data Extraction
- Authenticate with NASA Earthdata via
earthaccess - Search and load PACE MOANA L4M granules for the study bounding box
- Visualize spatial distributions of Synechococcus, Prochlorococcus, and picoeukaryotes
- Overlay NEFSC cetacean observations on phytoplankton maps
- Plot latitudinal abundance profiles for prokaryote groups
- Extract 3×3 pixel box statistics (mean, median, std, min, max, IQR) at each observation point across all survey dates; merge with existing chlorophyll data →
NEFSC_Offshore_Obs_With_Chl_and_MOANA.csv
Section 2 – Correlations: Group Size and Phytoplankton Variables
- Pearson and Spearman correlations between cetacean group size and each MOANA variable, by species
- Scatter plots, box plots by group-size category, and Spearman correlation heatmaps
Section 3 – Bathymetry
- Load GEBCO NetCDF and NEFSC isobath shapefiles
- Map bathymetric contours with cetacean observations
- Overlay chlorophyll and bathymetry
- Extract depth at each observation point via nearest-neighbor interpolation →
NEFSC_Offshore_Obs_With_Chl_MOANA_Depth.csv - Visualize depth distributions per species (box plots, violin plots, histograms, depth-zone stacked bars)
Section 4 – Environmental Niche Comparison
- Multi-variable niche analysis using all available environmental predictors: chlorophyll-a, chlorophyll variability, Synechococcus, Prochlorococcus, picoeukaryotes, phytoplankton carbon, SST, depth, and latitude
- Kruskal-Wallis tests for significant inter-species differences, followed by Mann-Whitney U post-hoc pairwise tests with Bonferroni correction
- Niche overlap quantified via histogram overlap index for each species pair × variable combination
- Visualization suite: distribution histograms, box/violin plots, 2D environmental space scatter plots, niche overlap heatmaps, radar charts, dot plots, biological vs. physical variable comparison panels, PCA biplots, hierarchical clustering dendrogram
- Prokaryote community composition (especially Synechococcus and picoeukaryotes) reveals strong niche partitioning that is not apparent from chlorophyll-a or particulate carbon alone.
- Sperm whales show near-zero overlap with all other species on Synechococcus and picoeukaryotes, consistent with their offshore, deep-diving habitat.
- Fin and Humpback whales show the highest niche overlap across most variables (shelf-edge generalists), while Common minke whales show zero Prochlorococcus overlap (coastal specialist).
- Carbon overlap is consistently higher than prokaryote overlap across species pairs, confirming that total biomass metrics mask ecologically meaningful differences in phytoplankton community structure.
- PCA and hierarchical clustering broadly confirm the Sperm whale as an outlier in multivariate environmental space, with Fin and Humpback grouping together.
- Environmental niche indicates different use by species within offshore region.
- There is so much potential for MOANA!
- OBIS SEAMAP NEFSC dataset: https://seamap.env.duke.edu/dataset/2368
- NASA Earthdata PACE MOANA product: https://search.earthdata.nasa.gov
- GEBCO 2025 Bathymetric Grid: https://www.gebco.net
- earthaccess Python library: https://earthaccess.readthedocs.io