1
|
Gallagher KL, Dinniman MS, Lynch HJ. Quantifying Antarctic krill connectivity across the West Antarctic Peninsula and its role in large-scale Pygoscelis penguin population dynamics. Sci Rep 2023; 13:12072. [PMID: 37495764 PMCID: PMC10372022 DOI: 10.1038/s41598-023-39105-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 07/20/2023] [Indexed: 07/28/2023] Open
Abstract
Antarctic krill (Euphausia superba) are considered a keystone species for higher trophic level predators along the West Antarctic Peninsula (WAP) during the austral summer. The connectivity of krill may play a critical role in predator biogeography, especially for central-place foragers such as the Pygoscelis spp. penguins that breed along the WAP during the austral summer. Antarctic krill are also heavily fished commercially; therefore, understanding population connectivity of krill is critical to effective management. Here, we used a physical ocean model to examine adult krill connectivity in this region using simulated krill with realistic diel vertical migration behaviors across four austral summers. Our results indicate that krill north and south of Low Island and the southern Bransfield Strait are nearly isolated from each other and that persistent current features play a role in this lack of inter-region connectivity. Transit and entrainment times were not correlated with penguin populations at the large spatial scales examined. However, long transit times and reduced entrainment correlate spatially with the areas where krill fishing is most intense, which heightens the risk that krill fishing may lead to limited krill availability for predators.
Collapse
Affiliation(s)
- Katherine L Gallagher
- Institute for Advanced Computational Sciences, Stony Brook University, Stony Brook, NY, 11794, USA.
| | - Michael S Dinniman
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, 23529, USA
| | - Heather J Lynch
- Institute for Advanced Computational Sciences, Stony Brook University, Stony Brook, NY, 11794, USA
- Department of Ecology & Evolution, Stony Brook University, Stony Brook, NY, 11790, USA
| |
Collapse
|
2
|
Lescroël A, Schmidt A, Ainley DG, Dugger KM, Elrod M, Jongsomjit D, Morandini V, Winquist S, Ballard G. High-resolution recording of foraging behaviour over multiple annual cycles shows decline in old Adélie penguins' performance. Proc Biol Sci 2023; 290:20222480. [PMID: 37015277 PMCID: PMC10072935 DOI: 10.1098/rspb.2022.2480] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/06/2023] [Indexed: 04/06/2023] Open
Abstract
Age-related variation in foraging performance can result from both within-individual change and selection processes. These mechanisms can only be disentangled by using logistically challenging long-term, longitudinal studies. Coupling a long-term demographic data set with high-temporal-resolution tracking of 18 Adélie penguins (Pygoscelis adeliae, age 4-15 yrs old) over three consecutive annual cycles, we examined how foraging behaviour changed within individuals of different age classes. Evidence indicated within-individual improvement in young and middle-age classes, but a significant decrease in foraging dive frequency within old individuals, associated with a decrease in the dive descent rate. Decreases in foraging performance occurred at a later age (from 12-15 yrs old to 15-18 yrs old) than the onset of senescence predicted for this species (9-11 yrs old). Foraging dive frequency was most affected by the interaction between breeding status and annual life-cycle periods, with frequency being highest during returning migration and breeding season and was highest overall for successful breeders during the chick-rearing period. Females performed more foraging dives per hour than males. This longitudinal, full annual cycle study allowed us to shed light on the changes in foraging performance occurring among individuals of different age classes and highlighted the complex interactions among drivers of individual foraging behaviour.
Collapse
Affiliation(s)
| | - Annie Schmidt
- Point Blue Conservation Science, Petaluma, CA 94954, USA
| | - David G. Ainley
- H. T. Harvey & Associates Ecological Consultants, Los Gatos, CA 95032, USA
| | - Katie M. Dugger
- US Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Corvallis, OR 97333, USA
| | - Megan Elrod
- Point Blue Conservation Science, Petaluma, CA 94954, USA
| | | | - Virginia Morandini
- Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, 104 Nash Hall, Corvallis, OR 97331, USA
- Fundación Migres, CIMA, N-340km 85, E-11380 Tarifa, Spain
- Museo Nacional de Ciencias Naturales, CSIC, C/Jose Gutierrez Abascal, 2, 28006 Madrid, Spain
| | - Suzanne Winquist
- Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Hatfield Marine Science Center, Newport, OR 97365, USA
| | - Grant Ballard
- Point Blue Conservation Science, Petaluma, CA 94954, USA
| |
Collapse
|
3
|
Emmerson L, Southwell C. Environment-triggered demographic changes cascade and compound to propel a dramatic decline of an Antarctic seabird metapopulation. GLOBAL CHANGE BIOLOGY 2022; 28:7234-7249. [PMID: 36214124 DOI: 10.1111/gcb.16437] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 08/07/2022] [Indexed: 06/16/2023]
Abstract
While seabirds are well-known for making a living under some of the harshest conditions on the planet, their capacity to buffer against unfavourable conditions can be stretched in response to ecosystem change. During population increases, overlap between conspecifics can limit population growth through competition for breeding or feeding resources. What is less well understood is the role that intrinsic processes play during periods of population decline or under a changing environment. We interrogate key demographic parameters and their biophysical drivers to understand the role of intrinsic and extrinsic drivers during a recent near halving of a large Adélie penguin (Pygoscelis adeliae) metapopulation. The loss of 154,000 breeding birds along the 100-km East Antarctic coastline centred around 63°E over the last decade diverges from a sustained increase over preceding decades and is contrary to recent models that predict a continued increase. The decline was initially triggered by changed environmental conditions: more extensive near-shore sea ice caused a reduction in breeding success. The evidence suggests this decline was exacerbated by feedback processes driving an inverse density-dependent decrease in fledgling survival in response to smaller cohort size. It appears that the old adage of safety in numbers may shape the fledgling penguins' chances of survival and, if compromised over multiple years, could exacerbate difficulties during population decline or if feedback processes arise. The likely interplay between demographic parameters meant that conditions were more unfavourable and negative effects more rapid than would be expected if demographic processes acted in isolation or independently. Failure to capture both intrinsic and extrinsic drivers in predictive population models may mean that the real impacts of climate change on species' populations are more severe than projections would lead us to believe. These results improve our understanding of population regulation during periods of rapid decline for long-lived marine species.
Collapse
Affiliation(s)
- Louise Emmerson
- Department of Climate Change, Energy, the Environment and Water, Australian Antarctic Division, Kingston, Tasmania, Australia
| | - Colin Southwell
- Department of Climate Change, Energy, the Environment and Water, Australian Antarctic Division, Kingston, Tasmania, Australia
| |
Collapse
|
4
|
Oosthuizen WC, Pistorius PA, Korczak‐Abshire M, Hinke JT, Santos M, Lowther AD. The foraging behavior of nonbreeding Adélie penguins in the western Antarctic Peninsula during the breeding season. Ecosphere 2022. [DOI: 10.1002/ecs2.4090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- W. Chris Oosthuizen
- Marine Apex Predator Research Unit, Institute for Coastal and Marine Research and Department of Zoology Nelson Mandela University Port Elizabeth South Africa
- Centre for Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences University of Cape Town Cape Town South Africa
| | - Pierre A. Pistorius
- Marine Apex Predator Research Unit, Institute for Coastal and Marine Research and Department of Zoology Nelson Mandela University Port Elizabeth South Africa
| | | | - Jefferson T. Hinke
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center National Marine Fisheries Service, National Oceanic and Atmospheric Administration La Jolla California USA
| | - Mercedes Santos
- Departamento Biología de Predadores Tope Instituto Antártico Argentino Buenos Aires Argentina
- Laboratorios Anexos Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata Buenos Aires Argentina
| | - Andrew D. Lowther
- Norwegian Polar Institute, Research Department Fram Centre Tromsø Norway
| |
Collapse
|
5
|
Hinke JT, Watters GM, Reiss CS, Santora JA, Santos MM. Acute bottlenecks to the survival of juvenile Pygoscelis penguins occur immediately after fledging. Biol Lett 2020; 16:20200645. [PMID: 33321063 PMCID: PMC7775978 DOI: 10.1098/rsbl.2020.0645] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/26/2020] [Indexed: 11/12/2022] Open
Abstract
Estimating when and where survival bottlenecks occur in free-ranging marine predators is critical for effective demographic monitoring and spatial planning. This is particularly relevant to juvenile stages of long-lived species for which direct observations of death are typically not possible. We used satellite telemetry data from fledgling Adélie, chinstrap and gentoo penguins near the Antarctic Peninsula to estimate the spatio-temporal scale of a bottleneck after fledging. Fledglings were tracked up to 106 days over distances of up to 2140 km. Cumulative losses of tags increased to 73% within 16 days of deployment, followed by an order-of-magnitude reduction in loss rates thereafter. The timing and location of tag losses were consistent with at-sea observations of penguin carcasses and bioenergetics simulations of mass loss to thresholds associated with low recruitment probability. A bootstrapping procedure is used to assess tag loss owing to death versus other factors. Results suggest insensitivity in the timing of the bottleneck and quantify plausible ranges of mortality rates within the bottleneck. The weight of evidence indicates that a survival bottleneck for fledgling penguins is acute, attributable to predation and starvation, and may account for at least 33% of juvenile mortality.
Collapse
Affiliation(s)
- Jefferson T. Hinke
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
| | - George M. Watters
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
| | - Christian S. Reiss
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
| | - Jarrod A. Santora
- Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA 95060, USA
| | - M. Mercedes Santos
- Departamento Biología de Predadores Tope, Instituto Antártico Argentino, San Martín B1650CSP, Argentina
- Laboratorios Anexos, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata B1904AMA, Argentina
| |
Collapse
|