Donald R. Kobayashi

Seamounts are prominent underwater mountains rising from the seafloor in ocean basins worldwide. These structures are often recognised in the deep-sea as benthic biodiversity hotspots, offering diverse habitats across depth gradients that support a wide variety of marine species. Seamounts are ecologically significant, and since 2006 the United Nations General Assembly (UNGA) has called for their protection as Vulnerable Marine Ecosystems (VMEs), together with cold-water coral gardens and hydrothermal vents. Despite this, seamounts face escalating threats from human activities, such as destructive fishing practices, the effects of climate change, and the potential impacts of deep-sea mining. These pressures underscore the need for enhanced conservation and management strategies.The Deep-Ocean Stewardship Initiative (DOSI) is a global network of thousands of experts from over 115 countries, which integrates science, technology, policy, law and economics to advise on ecosystem-based management of resource use in the deep ocean. In October 2024, the DOSI Fisheries Working Group with support from the UN Ocean Decade program Challenger 150, hosted the Seamount Science Summit workshop at the University of Hawai‘i, the first major gathering focused on seamount ecology and conservation in over a decade.The summit convened 26 global seamount experts to assess current ecological knowledge, review management practices, and develop strategies to improve resilience in seamount ecosystems amid ongoing anthropogenic pressures. Through presentations, plenary sessions and subgroup discussions, the expert group identified several frameworks to improve management of seamount ecosystems. Here, we present key outputs from the workshop including recommendations for Regional Fisheries Management Organizations (RFMOs) to manage seamounts as VMEs in order to prevent Significant Adverse Impacts (SAIs). We present frameworks to enhance data collection on seamounts fostering industry contributions towards scientific processes within RFMOs and enabling data-informed management of seamount ecosystems. Additionally, the expert group emphasises integrating cumulative impacts, including historical fishing pressures and current and projected climate change effects, to reduce bottom fishing impacts and enhance seamount ecosystem resilience. We also present science priorities and discuss pathways to overcome knowledge gaps in seamount research.

Bonefishes are a nearshore species targeted by non-commercial anglers and subsistence fishers in the Central and South Pacific islands. Among the bonefish species in the Indo-Pacific region, Albula glossodonta are known to have one of the widest geographic ranges, from the Red Sea to the Central Pacific, but it is unknown how dispersive A. glossodonta are between geographically isolated islands. Volunteer anglers collected A. glossodonta fin clips from the main Hawaiian Islands in the North Pacific, Anaa Atoll in the South Pacific, and intermediate Kiritimati Island (Line Islands) to assess the scale of dispersal and population structure within the Pacific Ocean. Population genomics was conducted based on 208 individuals and 7225 SNPs. Although adult A. glossodonta exhibit strong site fidelity, genomic results show no population differentiation between Oahu and Maui in Hawai‘i. Bonefishes exhibit significant population structure between Anaa and Hawai‘i (F_ST = 0.096), with intermediate Kiritimati comprising admixed fishes. A lengthy larval duration likely promotes connectivity between Pacific islands. Regional management regimes may be most appropriate for a species with this level of dispersal.

As past and present nontraditional students, our group of authors experienced firsthand a range of hurdles in our pursuit of ocean science graduate studies. Some of us attended graduate school while working full time in our fields as a means to advance our careers. Others returned to graduate school to pursue a second career in a new field. Combining our experiences with broader demographic information (Wendler et al., 2010) led us to define nontraditional ocean science graduate students as any of the following: mid-career professionals pursuing graduate degrees for career advancement and those who are embarking on a second career, hold an undergraduate degree outside of STEM, are in their thirties or older, or are balancing school with work and/or family responsibilities. While we highlight these characteristics, we recognize that there are others who self-identify as nontraditional, such as those facing a serious medical condition or disability. We hope that by sharing ways to remove barriers to entry, retention, and advancement for nontraditional students, our field will become more inclusive, equitable, and diverse.

Ocean eddies are coherent, rotating features that can modulate pelagic ecosystems across many trophic levels. These mesoscale features, which are ubiquitous at mid-latitudes¹, may increase productivity of nutrient-poor regions^2,3, accumulate prey⁴ and modulate habitat conditions in the water column⁵. However, in nutrient-poor subtropical gyres—the largest marine biome—the role of eddies in modulating behaviour throughout the pelagic predator community remains unknown despite predictions for these gyres to expand⁶ and pelagic predators to become increasingly important for food security⁷. Using a large-scale fishery dataset in the North Pacific Subtropical Gyre, we show a pervasive pattern of increased pelagic predator catch inside anticyclonic eddies relative to cyclones and non-eddy areas. Our results indicate that increased mesopelagic prey abundance in anticyclone cores^4,8 may be attracting diverse predators, forming ecological hotspots where these predators aggregate and exhibit increased abundance. In this energetically quiescent gyre, we expect that isolated mesoscale features (and the habitat conditions in them) exhibit primacy over peripheral submesoscale dynamics in structuring the foraging opportunities of pelagic predators. Our finding that eddies influence coupling of epi- to mesopelagic communities corroborates the growing evidence that deep scattering layer organisms are vital prey for a suite of commercially important predator species⁹ and, thus, provide valuable ecosystem services.

Our changing climate poses growing challenges for effective management of marine life, ocean ecosystems, and human communities. Which species are most vulnerable to climate change, and where should management focus efforts to reduce these risks? To address these questions, the National Oceanic and Atmospheric Administration (NOAA) Fisheries Climate Science Strategy called for vulnerability assessments in each of NOAA’s ocean regions. The Pacific Islands Vulnerability Assessment (PIVA) project assessed the susceptibility of 83 marine species to the impacts of climate change projected to 2055. In a standard Rapid Vulnerability Assessment framework, this project applied expert knowledge, literature review, and climate projection models to synthesize the best available science towards answering these questions. Here we: (1) provide a relative climate vulnerability ranking across species; (2) identify key attributes and factors that drive vulnerability; and (3) identify critical data gaps in understanding climate change impacts to marine life. The invertebrate group was ranked most vulnerable and pelagic and coastal groups not associated with coral reefs were ranked least vulnerable. Sea surface temperature, ocean acidification, and oxygen concentration were the main exposure drivers of vulnerability. Early Life History Survival and Settlement Requirements was the most data deficient of the sensitivity attributes considered in the assessment. The sensitivity of many coral reef fishes ranged between Low and Moderate, which is likely underestimated given that reef species depend on a biogenic habitat that is extremely threatened by climate change. The standard assessment methodology originally developed in the Northeast US, did not capture the additional complexity of the Pacific region, such as the diversity, varied horizontal and vertical distributions, extent of coral reef habitats, the degree of dependence on vulnerable habitat, and wide range of taxa, including data-poor species. Within these limitations, this project identified research needs to sustain marine life in a changing climate.

Here we present an assessment of eddy activity in a 3,500 × 2,000 km region of the North Pacific. Eddies were identified and tracked within a numerical simulation that used the Massachusetts Institute of Technology general circulation model and an eddy characterization algorithm. Spatially, eddy births were more frequent: (1) nearshore (cyclones) and offshore (anticyclones) on the windward side of the main Hawai‘ian Islands; (2) in patches of cyclones and anticyclones that resembled the dipole structure of wind stress curl along the islands’ leeward side; and (3) in zonal patches of eddies of both polarities west and north of the islands. Temporally, high eddy activities occurred in spring. There was a meridional distribution of eddy lifespans, which increased northward. Cyclones were more abundant, longer‐lived, smaller, and more nonlinear. Reef fish spawning locations in Hawai‘i coincide with the regions of high eddy activity, with nonlinear eddies responsible for high larval retention.

Local adaptation of marine and diadromous species is thought to be a product of larval dispersal, settlement mortality, and differential reproductive success, particularly in heterogeneous post-settlement habitats. We evaluated this premise with an oceanographic passive larval dispersal model coupled with individual-based models of post-settlement selection and reproduction to infer conditions that underlie local adaptation in Sicyopterus stimpsoni, an amphidromous Hawaiian goby known for its ability to climb waterfalls. Our model results demonstrated that larval dispersal is spatio-temporally asymmetric, with more larvae dispersed from the southeast (the Big Island) to northwest (Kaua‘i) along the archipelago, reflecting prevailing conditions such as El Niño/La Niña oscillations. Yet connectivity is nonetheless sufficient to result in homogenous populations across the archipelago. We also found, however, that ontogenetic shifts in habitat can give rise to adaptive morphological divergence when the strength of predation-driven post-settlement selection crosses a critical threshold. Notably, our simulations showed that larval dispersal is not the only factor determining the likelihood of morphological divergence. We found adaptive potential and evolutionary trajectories of S. stimpsoni were greater on islands with stronger environmental gradients and greater variance in larval cohort morphology due to fluctuating immigration. Contrary to expectation, these findings indicate that immigration can act in concert with selection to favor local adaptation and divergence in species with marine larval dispersal. Further development of model simulations, parameterized to reflect additional empirical estimates of abiotic and biotic factors, will help advance our understanding of the proximate and ultimate mechanisms driving adaptive evolution, population resilience, and speciation in marine-associated species.

The movement of juvenile loggerhead turtles (n = 42) out-fitted with satellite tags and released in oceanic waters off New Caledonia was examined and compared with ocean circulation data. Merging of the daily turtle movement data with drifter buoy movements, OSCAR (Ocean Surface Current Analyses - Real time) circulation data, and three different vertical strata (0–5 m, 0–40 m, 0–100 m) of HYCOM (HYbrid Coordinate Ocean Model) circulation data indicated the turtles were swimming against the prevailing current in a statistically significant pattern. This was not an artifact of prevailing directions of current and swimming, nor was it an artifact of frictional slippage. Generalized additive modeling was used to decompose the pattern of swimming into spatial and temporal components. The findings are indicative of a positive rheotaxis whereby an organism is able to detect the current flow and orient itself to swim into the current flow direction or otherwise slow down its movement. Potential mechanisms for the means and adaptive significance of rheotaxis in oceanic juvenile loggerhead turtles are discussed.