439
HARPs were maintained nearly continuously at these representative oil-exposed
and oil-unexposed monitoring sites to detect marine mammal sound production as a
proxy for animal presence across the region. Marine mammal species and genera
were then distinguished in the long-term passive acoustic recordings based on the
characteristics of their sounds. Species monitored include sperm whales, Cuvier’s
and Gervais’ beaked whales, Risso’s dolphin, and pygmy/dwarf sperm whales
(Kogia spp.), delphinids in the genus Stenella (Atlantic spotted, pantropical spotted,
spinner, striped, and Clymene dolphins), and blackfish (primarily short-finned pilot
whales).
Bottlenose dolphin health assessments began in 2011 in Barataria Bay, Louisiana
(Schwacke et al. 2013). Health metrics from resident bottlenose dolphins in
Barataria Bay, which was heavily oiled by the DWH event (Michel et al. 2013),
were compared to an unexposed reference population in Sarasota Bay, Florida
(Fig. 26.1).
Shorter-term marine mammal studies following the DWH event included lowfrequency passive acoustic monitoring for Bryde’s whales on the west Florida shelf
in 2010 and 2011 (Rice et al. 2014), satellite tagging efforts aimed at understanding
sperm whale distributions (Mate unpublished data), and short-term passive acoustic
monitoring near the DWH wellhead site (Ackleh et al. 2012). In the absence of
long- term data, various population modeling efforts were also undertaken to try to
estimate population-level effects and recovery times based on assumed vital rates
(Farmer et al. 2018; Ackleh et al. 2018; Schwacke et al. 2017).
In an effort to mitigate the impact of the spill on sea turtle nesting beaches,
25,000 Kemp’s ridley and loggerhead eggs were transported from beaches in the
GOM to the Atlantic coast in Florida (Inkley et al. 2013). Following the DWH spill,
transect searches were conducted in convergence zones within the spill area to rescue oceanic juvenile sea turtles and to document species composition and oiling
status (McDonald et al. 2017). Aerial surveys were conducted on the continental
shelf throughout the northern GOM to the 200-m isobath between April and
September 2010, documenting the distribution and abundance of neritic sea turtles
throughout the DWH spill area (Garrison 2015).
Estimates of the probabilities of oil exposure for sea turtles present within the
area of the spill were generated from direct observations of surface-pelagic juvenile
sea turtles (Stacy 2012) and satellite-derived surface oil distributions (Wallace et al.
2017). Abundance and source populations for impacted turtles were predicted using
ocean circulation and particle tracking simulation models, estimating that 321,401
green, loggerhead, and Kemp’s ridley turtles were likely within the spill site, originating primarily from Mexico and Costa Rica (Putman et al. 2015).
26 Impacts of the Deepwater Horizon Oil Spill on Marine Mammals and Sea Turtles
HARPs were maintained nearly continuously at these representative oil-exposed
and oil-unexposed monitoring sites to detect marine mammal sound production as a
proxy for animal presence across the region. Marine mammal species and genera
were then distinguished in the long-term passive acoustic recordings based on the
characteristics of their sounds. Species monitored include sperm whales, Cuvier’s
and Gervais’ beaked whales, Risso’s dolphin, and pygmy/dwarf sperm whales
(Kogia spp.), delphinids in the genus Stenella (Atlantic spotted, pantropical spotted,
spinner, striped, and Clymene dolphins), and blackfish (primarily short-finned pilot
whales).
Bottlenose dolphin health assessments began in 2011 in Barataria Bay, Louisiana
(Schwacke et al. 2013). Health metrics from resident bottlenose dolphins in
Barataria Bay, which was heavily oiled by the DWH event (Michel et al. 2013),
were compared to an unexposed reference population in Sarasota Bay, Florida
(Fig. 26.1).
Shorter-term marine mammal studies following the DWH event included lowfrequency passive acoustic monitoring for Bryde’s whales on the west Florida shelf
in 2010 and 2011 (Rice et al. 2014), satellite tagging efforts aimed at understanding
sperm whale distributions (Mate unpublished data), and short-term passive acoustic
monitoring near the DWH wellhead site (Ackleh et al. 2012). In the absence of
long- term data, various population modeling efforts were also undertaken to try to
estimate population-level effects and recovery times based on assumed vital rates
(Farmer et al. 2018; Ackleh et al. 2018; Schwacke et al. 2017).
In an effort to mitigate the impact of the spill on sea turtle nesting beaches,
25,000 Kemp’s ridley and loggerhead eggs were transported from beaches in the
GOM to the Atlantic coast in Florida (Inkley et al. 2013). Following the DWH spill,
transect searches were conducted in convergence zones within the spill area to rescue oceanic juvenile sea turtles and to document species composition and oiling
status (McDonald et al. 2017). Aerial surveys were conducted on the continental
shelf throughout the northern GOM to the 200-m isobath between April and
September 2010, documenting the distribution and abundance of neritic sea turtles
throughout the DWH spill area (Garrison 2015).
Estimates of the probabilities of oil exposure for sea turtles present within the
area of the spill were generated from direct observations of surface-pelagic juvenile
sea turtles (Stacy 2012) and satellite-derived surface oil distributions (Wallace et al.
2017). Abundance and source populations for impacted turtles were predicted using
ocean circulation and particle tracking simulation models, estimating that 321,401
green, loggerhead, and Kemp’s ridley turtles were likely within the spill site, originating primarily from Mexico and Costa Rica (Putman et al. 2015).
26 Impacts of the Deepwater Horizon Oil Spill on Marine Mammals and Sea Turtles