Chesapeake DolphinWatch weekly data

Bottlenose dolphins (Tursiops truncatus) are migratory marine mammals that
live in both open-ocean and coastal habitats. Although widely studied,
little is known about their occurrence patterns in the highly urbanized
Chesapeake Bay, U.S.A. The goal of this study was to establish the spatial
and temporal distribution of bottlenose dolphins throughout this large
estuarine system and use statistical modeling techniques to determine how
their distribution relates to environmental factors. Three years
(2017-2019) of observational dolphin sighting reports from a
citizen-science database, Chesapeake DolphinWatch, were used to determine
relative occurrence throughout the estuary. The dolphins had a distinct
temporal pattern, most commonly sighted during summer months with a peak
in July. This pattern of observed occurrence was confirmed with passive
acoustic detections of dolphin echolocation clicks. Using a Generalized
Additive Model (GAM), dolphin presence was found to be significantly
correlated to spring tidal phase, warm water temperature, and salinity
ranging from 6 – 22 PPT. Further, we were able to use these GAMs with a
test dataset to predict species occurrence in the Bay, which were
statistically correlated to the actual number of dolphin sighting reports
during that time. These models can be implemented as a predictive tool for
species occurrence and help to inform management of this protected species
within the Chesapeake Bay.