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Abstract Killer whales ( Orcinus orca ) are top predators throughout the world’s oceans. In the North Pacific, the species is divided into three ecotypes—resident (fish-eating), transient (mammal-eating), and offshore (largely shark-eating)—that are genetically and acoustically distinct and have unique roles in the marine ecosystem. In this study, we examined the year-round distribution of killer whales in the northern Gulf of Alaska from 2016 to 2020 using passive acoustic monitoring. We further described the daily acoustic residency patterns of three killer whale populations (southern Alaska residents, Gulf of Alaska transients, and AT1 transients) for one year of these data. Highest year-round acoustic presence occurred in Montague Strait, with strong seasonal patterns in Hinchinbrook Entrance and Resurrection Bay. Daily acoustic residency times for the southern Alaska residents paralleled seasonal distribution patterns. The majority of Gulf of Alaska transient detections occurred in Hinchinbrook Entrance in spring. The depleted AT1 transient killer whale population was most often identified in Montague Strait. Passive acoustic monitoring revealed that both resident and transient killer whales used these areas much more extensively than previously known and provided novel insights into high use locations and times for each population. These results may be driven by seasonal foraging opportunities and social factors and have management implications for this species.
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Metazoan diversity and seasonality through eDNA metabarcoding at a Mediterranean long-term ecological research site
Abstract Metabarcoding of environmental DNA has provided striking insights into marine microbial diversity. With this approach, we assessed the diversity of metazoan assemblages and their temporal variations at the Long-Term Ecological Research site MareChiara (LTER-MC) in the Gulf of Naples (Mediterranean Sea). The Illumina sequencing of the V4-18S rRNA fragment from 48 surface samples collected from 2011 to 2013 produced a total of 5 011 047 marine metazoan reads. The normalized dataset was generally dominated by copepods (60.3%), followed by annelids (34.7%) mostly represented by the invasive benthic polychaete Hydroides elegans. Non-copepod holoplankton was mainly represented by siphonophores, rotifers, and appendicularians, with occasional mass occurrences of jellyfish. The rest of meroplankton (mainly molluscs, annelids, and anthozoans) showed a high diversity, covering all 11 zooplankton phyla, from Porifera to Craniata. A high number of copepod genera were identified, with seasonal recurrence matching patterns observed in 30 years of studies in the Gulf of Naples. Despite limitations related to the molecular marker resolution and reference dataset, the study provided valuable insights into diversity and seasonal patterns of the whole metazoan assemblage, expanding the knowledge on rare or hardly identifiable taxa and confirming DNA metabarcoding as a powerful approach to be integrated at LTER sites.
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- Award ID(s):
- 1840868
- PAR ID:
- 10280695
- Editor(s):
- Fields, David
- Date Published:
- Journal Name:
- ICES Journal of Marine Science
- ISSN:
- 1054-3139
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/icesjms/fsab059
