Nest survival of Seaside Sparrows (Ammospiza maritima) in the wake of the Deepwater Horizon oil spill

PLOS ONE RESEARCH ARTICLE Nest survival of Seaside Sparrows (Ammospiza maritima) in the wake of the Deepwater Horizon oil spill Megan E. Hart1, Anna Perez-Umphrey ID2, Philip C. Stouffer2, Christine Bergeon Burns2, Andrea Bonisoli-Alquati2¤, Sabrina S. Taylor ID2, Stefan Woltmann ID1* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Center of Excellence for Field Biology, and Department of Biology, Austin Peay State University, Clarksville, TN, United States of America, 2 School of Renewable Natural Resources, Louisiana State University and AgCenter, Baton Rouge, LA, United States of America ¤ Current address: Department of Biological Sciences, California State Polytechnic University, Pomona, Pomona, CA, United States of America * Abstract OPEN ACCESS Citation: Hart ME, Perez-Umphrey A, Stouffer PC, Burns CB, Bonisoli-Alquati A, Taylor SS, et al. (2021) Nest survival of Seaside Sparrows (Ammospiza maritima) in the wake of the Deepwater Horizon oil spill. PLoS ONE 16(10): e0259022. https://doi.org/10.1371/journal. pone.0259022 Editor: Wei Wu, The University of Southern Mississippi, UNITED STATES Received: December 30, 2020 Accepted: October 11, 2021 Published: October 26, 2021 Copyright: © 2021 Hart et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org; rat data DOI: R4.x264.219-003, PAH data DOIs R4. x264.000:0056 and R6.x808.000:0042, sparrow nest survival and vegetation data DOI R6. x808.000:0008. Funding: This research was made possible by a grant from The Gulf of Mexico Research Initiative In 2010, the Deepwater Horizon oil spill released an estimated 4.9 million barrels of oil into the Gulf of Mexico, damaging coastal ecosystems. Seaside Sparrows (Ammospiza maritima)—a year-round resident of Gulf Coast salt marshes—were exposed to oil, as shown by published isotopic and molecular analyses, but fitness consequences have not been clarified. We monitored nests around two bays in Plaquemines Parish, Louisiana, USA from 2012–2017 to assess possible impacts on the nesting biology of Seaside Sparrows. A majority of nests failed (76% of known-fate nests, N = 252 nests, 3521 exposure-days) during our study, and predation was the main cause of nest failure (~91% of failed nests). Logistic exposure analysis revealed that daily nest survival rate: (1) was greater at nests with denser vegetation at nest height, (2) was higher in the more sheltered bay we studied, (3) decreased over the course of the breeding season in each year, and (4) was not correlated with either sediment polycyclic aromatic hydrocarbon concentrations or estimated predator abundance during the years for which we had those data. Although the Deepwater Horizon spill impacted other aspects of Seaside Sparrow ecology, we found no definitive effect of initial oiling or oiled sediment on nest survival during 2012–2017. Because predation was the overwhelming cause of nest failure in our study, additional work on these communities is needed to fully understand demographic and ecological impacts of storms, oil spills, other pollutants, and sea-level rise on Seaside Sparrows and their predators. Introduction Oil spills have detrimental and often long-lasting effects on wildlife populations [1–5]. On April 20, 2010, the Deepwater Horizon (DWH) oil platform exploded in the Gulf of Mexico, resulting in the uncontrolled release of an estimated 4.9 million barrels of oil over a period of 87 days. Ecosystems throughout the northern Gulf of Mexico were impacted [6–8], including PLOS ONE | https://doi.org/10.1371/journal.pone.0259022 October 26, 2021 1 / 17 PLOS ONE to the Coastal Waters Consortium. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. Seaside Sparrow nest survival after the Deepwater Horizon oil spill ca. 1700 km of shoreline, 45% of which were wetlands [9, 10]. Of the coastal wetlands impacted by the DWH, 95% were in Louisiana, and the majority of these were salt marshes [10]. Oil exposure has detrimental direct and indirect effects on organisms, which range from death and acute, toxic effects to chronic or cascading impacts [4, 11–14]. The most immediate impacts of oil are from physical contact or ingestion [15]; an estimated 600,000–800,000 birds were killed during the DWH spill [16]. Negative impacts on bird populations also result from long-term exposure to polycyclic aromatic hydrocarbons (PAHs) via multiple pathways [17– 19], or from changes in habitat quality or resource availability due to oiling [4, 13]. For example, following the Exxon Valdez spill in Alaska, Harlequin Duck (Histrionicus histrionicus) populations did not fully recover for at least 9 years post-spill [20], and experienced chronic exposure to oil for at least 20 years [17]. A combination of chronic exposure to PAHs and reduced food availability also depressed Pigeon Guillemot (Cepphus columba) populations for several years following the Valdez spill [2]. Given the greater challenge of cleaning oiled marshes compared to rocky shores of Alaska, it is reasonable to expect that PAHs will remain in marshes in various states of degradation along the Gulf of Mexico for many years [8, 21] The DWH spill had both immediate and longer-term impacts on the salt marshes of Louisiana [8], and the severity of oiling varied along the Louisiana coast depending on currents and southern exposure of marsh edges to the open Gulf [10]. Edge vegetation of heavily oiled salt marsh died, leading to increased erosion and land loss in oiled areas [22], and PAH levels in marsh edge sediments remained elevated at least through 2018 [21]. Nearshore aboveground plant biomass and vegetation health both decreased on oiled plots [23], and some plant communities changed due to differential sensitivity to oiling [24]. Salt marsh animal communities including both invertebrates and vertebrates were impacted by the spill (e.g., arthropods [25], tabanid flies [26], snails [27], fishes [5, 28], birds [14, 29–32]). Nonetheless, some plant and animal communities appeared to recover within 4–7 years following the DWH spill [33–35]. The Seaside Sparrow (Ammospiza maritima) is endemic to salt marshes of the Atlantic and Gulf coasts of North America, and is abundant in southern Louisiana marshes impacted by the DWH spill [14, 36]. Seaside Sparrow populations in the region (A. m. fisheri; a non-migratory group) are considered good indicators of healthy salt marsh because although Seaside Sparrows are vulnerable to habitat loss, the (...truncated)