Tissue Element Levels and Heavy Metal Burdens in Bottlenose Dolphins That Stranded in the Mississippi Sound Surrounding the 2019 Unusual Mortality Event
Nelmarie Landrau-Giovannetti,
Ryanne Murray,
Stephen Reichley,
Debra Moore,
Theresa Madrigal,
Ashli Brown,
Ashley Meredith,
Christina Childers,
Darrell Sparks,
Moby Solangi,
Anna Linhoss,
Beth Peterman,
Mark Lawrence,
Barbara L. F. Kaplan
Affiliations
Nelmarie Landrau-Giovannetti
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA
Ryanne Murray
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA
Stephen Reichley
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA
Debra Moore
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA
Theresa Madrigal
Institute for Marine Mammal Studies, Gulfport, MS 39503, USA
Ashli Brown
Mississippi State Chemical Laboratory, Mississippi State University, Mississippi State, MS 39762, USA
Ashley Meredith
Mississippi State Chemical Laboratory, Mississippi State University, Mississippi State, MS 39762, USA
Christina Childers
Mississippi State Chemical Laboratory, Mississippi State University, Mississippi State, MS 39762, USA
Darrell Sparks
Mississippi State Chemical Laboratory, Mississippi State University, Mississippi State, MS 39762, USA
Moby Solangi
Institute for Marine Mammal Studies, Gulfport, MS 39503, USA
Anna Linhoss
Department of Biosystems Engineering, Samuel Ginn College of Engineering, Auburn University, Auburn, AL 36849, USA
Beth Peterman
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA
Mark Lawrence
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA
Barbara L. F. Kaplan
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA
In 2019, an unusual mortality event (UME) affected bottlenose dolphins (Tursiops truncatus) in the Mississippi Sound (MSS) following an extended dual opening of the Bonnet Carré Spillway (BCS), which prevents flooding in New Orleans. This resulted in low salinity, skin lesions, and electrolyte imbalances in dolphins. Additionally, the influx likely altered the MSS’s environmental chemical composition, including levels of heavy metals and metalloids; thus, we quantified heavy metals, metalloids, and essential elements in the tissues of dolphins that stranded in the MSS before and after the 2019 UME. We hypothesized that levels of heavy metals and metalloids (such as mercury (Hg), arsenic (As), lead (Pb), and cadmium (Cd)) would not show significant changes post-UME. Indeed, we found no major changes associated with the UME in most metals; sodium (Na) and magnesium (Mg) levels were lower in several tissues after 2019, which correlated with the average yearly salinity measured from the MSS. Toxic metals and metalloids were detectable with some changes over time; however, the selenium (Se):Hg molar ratio increased in some tissues post-2019. Additionally, we confirmed that Hg can bioaccumulate, with positive correlations between Hg levels and dolphin size as assessed by straight length. Overall, our findings indicate that freshwater incursions into the MSS can alter dolphin exposure to essential and toxic elements.
