Examining the effect of salinity on dolphin mortality using Lagrangian particle tracking in a hydrodynamic model

Details

• Journal Title:
  Estuarine, Coastal and Shelf Science
• Personal Author:
  Shahidzadehasadi, Mehrzad ; Linhoss, Anna ; Moore, Debra ; Reichley, Stephen ; Mickle, Paul ; Lawrence, Mark
• NOAA Program & Office:
  NGI (Northern Gulf Institute)
• Description:
  Numerous dolphins are found dead on beaches and waterways of the Gulf of Mexico and Mississippi Sound every year. In 2019 an unusual mortality event (UME) occurred when 337 deceased bottlenose dolphins were stranded between Louisiana, Mississippi, Alabama, and Florida. According to NOAA, based on observations of skin lesions or distinct ulcerative dermatitis and other internal pathologic findings and the environmental conditions during that period of time, the identified cause of this UME was determined to be protracted exposure to low salinity waters. Dolphin carcasses are often found stranded on beaches days after they die. Consequently, their initial place of death is unknown. In this study, an existing 2D hydrodynamic model (EFDC+ 11.2) of the Mississippi Sound simulated by Armandei et al. (2021) was used to track dolphin carcass movement and to simulate salinity at the time and location of each predicted dolphin's death. Particles within the Lagrangian particle tracking module were used to represent the movement of 19 dolphin carcasses. A large number of particles (virtual dolphin carcasses) were seeded throughout the model domain and tracked for five days. These results were used to hindcast each dolphin's original location of death. The results indicate that the most likely place of death for 12 dolphins stranded on the beaches of Mississippi, along with the two found on Ship and Horn Islands, was west of their stranding location., For both of the dolphins stranded on Dauphin Island, the most likely place of death was in the Mobile Bay area north of where they were found. The remaining three dolphins found dead on barrier islands, most likely originally died in close proximity to their stranding locations. The average simulated salinity of all the dolphins' most probable original place of death was below five except for two cases. These results are compared to the salinity of the Mississippi Sound during Bonnet Carré spillway opening and non-opening dates. The results highlight the significant impact of the spillway's opening on the reduction of salinity and its association with dolphin mortality.
• Source:
  Estuarine, Coastal and Shelf Science, 297, 108605
• DOI:
  https://doi.org/10.1016/j.ecss.2023.108605
• ISSN:
  0272-7714
• Format:
  pdf
• Publisher:
  Elsevier BV
• Document Type:
  Journal Article
• License:
  https://creativecommons.org/licenses/by/4.0/
• Rights Information:
  CC BY
• Compliance:
  Library
• Main Document Checksum:
  urn:sha-512:b52ea49bc2c3ae9df6d5a549b93211c45d275ed4dd9c7077b1176ef81f95821bfebb394055aaaa387e6d1d0cc9537c7a7e37f1733ca7e533ee477f8338db16ef
• Download URL:
  https://repository.library.noaa.gov/view/noaa/68269/noaa_68269_DS1.pdf
• File Type:
  [PDF - 15.09 MB ]