The eastern North Pacific is simultaneously experiencing ocean warming (OW) and ocean acidification (OA), which may negatively affect fish early life stages. Pacific cod (
Gadus macrocephalus
) is an ...economically and ecologically important species with demonstrated sensitivity to OW and OA, but their combined impacts are unknown. Through a ~ 9-week experiment, Pacific cod embryos and larvae were reared at one of six combinations of three temperatures (3, 6, 10 °C) and two CO
2
levels (ambient: ~ 360 μatm; high: ~ 1560 μatm) in a factorial design. Both embryonic and larval mortality were highest at the warmest temperature. Embryonic daily mortality rates were lower under elevated CO
2
and there was no effect of CO
2
level on larval daily mortality rates. Growth rates of young larvae (0 to 11 days post-hatch) were faster at warmer temperatures and at high CO
2
levels, but growth during the 11–28 days post-hatch interval increased by temperature alone. The condition of larvae decreased with age, but less markedly under high CO
2
levels. However, at 6 °C, fish incubated in ambient CO
2
remained in higher condition than fish in the high CO
2
treatment throughout the experiment. Overall, temperature had the greater influence on Pacific cod early life stages across each measurement endpoint, while CO
2
effects were more modest and inconsistent. Subtle developmental differences in larval Pacific cod could be magnified later in life and important in the context of recruitment. These results show the complexity of stage- and trait-specific responses to and value of investigating the combined effects of co-occurring climatic stressors.
Ocean acidification (OA) research seeks to understand how marine ecosystems and global elemental cycles will respond to changes in seawater carbonate chemistry in combination with other environmental ...perturbations such as warming, eutrophication, and deoxygenation. Here, we discuss the effectiveness and limitations of current research approaches used to address this goal. A diverse combination of approaches is essential to decipher the consequences of OA to marine organisms, communities, and ecosystems. Consequently, the benefits and limitations of each approach must be considered carefully. Major research challenges involve experimentally addressing the effects of OA in the context of large natural variability in seawater carbonate system parameters and other interactive variables, integrating the results from different research approaches, and scaling results across different temporal and spatial scales.
In the past decade, much progress has been made in real-time passive acoustic monitoring of marine mammal occurrence and distribution from autonomous platforms (e.g., gliders, floats, buoys), but ...current systems focus primarily on a single call type produced by a single species, often from a single location. A hardware and software system was developed to detect, classify, and report 14 call types produced by 4 species of baleen whales in real time from ocean gliders. During a 3-week deployment in the central Gulf of Maine in late November and early December 2012, two gliders reported over 25,000 acoustic detections attributed to fin, humpback, sei, and right whales. The overall false detection rate for individual calls was 14%, and for right, humpback, and fin whales, false predictions of occurrence during 15-min reporting periods were 5% or less. Transmitted pitch tracks--compact representations of sounds--allowed unambiguous identification of both humpback and fin whale song. Of the ten cases when whales were sighted during aerial or shipboard surveys and a glider was within 20 km of the sighting location, nine were accompanied by real-time acoustic detections of the same species by the glider within ±12 h of the sighting time.
To use the framework of the Health Belief Model (HBM) to explore factors associated with metformin use among adults with prediabetes.
We analyzed survey data from 200 metformin users and 1,277 ...nonmetformin users with prediabetes identified from a large, insured workforce. All subjects were offered the National Diabetes Prevention Program (DPP) at no out-of-pocket cost. We constructed bivariate and multivariate models to investigate how perceived threat, perceived benefits, self-efficacy, and cues to action impacted metformin use and how demographic, clinical, sociopsychological, and structural variables impacted the associations.
Adults with prediabetes who used metformin were younger and more likely to be women and to have worse self-rated health and higher BMIs than those with prediabetes who did not use metformin. Those who used metformin were also more likely to be aware of their prediabetes and to have a personal history of gestational diabetes mellitus or a family history of diabetes. After consideration of perceived threat, perceived benefits, self-efficacy, and cues to action, the only independent predictors of metformin use were younger age, female sex, higher BMI, and cues to action, most specifically, a doctor offering metformin therapy.
Demographic and clinical factors and cues to action impact the likelihood of metformin use for diabetes prevention. Perceived threat, perceived benefits, and self-efficacy were not independently associated with metformin use. These results highlight the importance of patient-centered primary care and shared decision-making in diabetes prevention. Clinicians should proactively offer metformin to patients with prediabetes to facilitate effective diabetes prevention.
Flatfishes support a number of important fisheries in Alaskan waters and represent major pathways of energy flow through the ecosystem. Despite their economic and ecological importance, little is ...known about the use of habitat by juvenile flatfishes in the eastern Bering Sea. This study describes the habitat characteristics of juvenile flatfishes in coastal waters along the Alaska Peninsula and within the Port Moller–Herendeen Bay system, the largest marine embayment in the southern Bering Sea. The two most abundant species, northern rock sole and yellowfin sole, differed slightly in habitat use with the latter occupying slightly muddier substrates. Both were more common along the open coastline than they were within the bay, whereas juvenile Alaska plaice were more abundant within the bay than along the coast and used shallow waters with muddy, high organic content sediments. Juvenile Pacific halibut showed the greatest shift in distribution between age classes: age-0 fish were found in deeper waters (~ 30m) along the coast, whereas older juveniles were found in the warmer, shallow waters within the bay, possibly due to increased thermal opportunities for growth in this temperature-sensitive species. Three other species, starry flounder, flathead sole, and arrowtooth flounder, were also present, but at much lower densities. In addition, the habitat use patterns of spring-spawning flatfishes (northern rock sole, Pacific halibut, and Alaska plaice) in this region appear to be strongly influenced by oceanographic processes that influence delivery of larvae to coastal habitats. Overall, use of the coastal embayment habitats appears to be less important to juvenile flatfishes in the Bering Sea than in the Gulf of Alaska.
•Little is known about juvenile flatfish habitat use in the Bering Sea.•Habitat use was examined along the Alaska Peninsula and in a large marine embayment.•Habitat use was species specific and associated with depth and sediment type.•Commercially important species were more abundant along the coast than in the bay.•Inshore habitat use appears constrained by larval delivery in multiple species.
Abstract
Hurst, T. P., Fernandez, E. R., and Mathis, J. T. 2013. Effects of ocean acidification on hatch size and larval growth of walleye pollock (Theragra chalcogramma). – ICES Journal of Marine ...Science, 70: 812–822. Rising atmospheric concentrations of CO2 are predicted to decrease the pH of high-latitude oceans by 0.3–0.5 units by 2100. Because of their limited capacity for ion exchange, embryos and larvae of marine fishes are predicted to be more sensitive to elevated CO2 than juveniles and adults. Eggs and larvae of walleye pollock (Theragra chalcogramma) were incubated across a broad range of CO2 levels (280–2100 µatm) to evaluate sensitivity in this critical resource species. Slightly elevated CO2 levels (∼450 µatm) resulted in earlier hatching times, but differences among egg batches were greater than those observed across CO2 treatments. Egg batches differed significantly in size-at-hatch metrics, but we observed no consistent effect of CO2 level. In three independent experiments, walleye pollock were reared at ambient and elevated CO2 levels through the early larval stage (to ∼30 days post-hatch). Across trials, there were only minor effects of CO2 level on size and growth rate, but fish in the ambient treatments tended to be slightly smaller than fish reared at elevated CO2 levels. These results suggest that growth potential of early life stages of walleye pollock is resilient with respect to the direct physiological effects of ocean acidification.
Abstract
The rapid decline in Pacific cod (
Gadus macrocephalus
, Gadidae) biomass following multiple Gulf of Alaska marine heatwaves (2014–2016 and 2019) may be one of the most dramatic documented ...changes in a sustainably managed marine fishery. As such, fisheries managers are exploring new recruitment paradigms for Pacific cod under novel environmental conditions. In this review, we address the challenges of managing and forecasting Pacific cod populations in the Eastern Pacific where thermal habitats for early life stages are undergoing varying rates of change across space and time. We use observational data to examine changes in distribution, abundance and demographics of the population from 1993 to 2020, and model contemporary and future changes of thermal habitat for both spawning success and age‐0 juvenile growth potential. Results indicate that reduced spawning habitat and early life stage abundance may be a precursor to regional population decline, but the recent apparent increases in size‐at‐age of pre‐recruits will have unknown impacts on future recruitment in these regions. We contend that continued monitoring of early life stages will be necessary to track changes in phenology and growth that likely determine size‐at‐age and the survival trajectories of year classes into the adult population. These include complex size‐ and temperature‐dependent energetics spanning seasonal habitats through the first winter. Climate‐ready management of Pacific cod will, therefore, require new process investigations beyond single‐season surveys focused on one‐life stage.
Understanding patterns of foraging and competition in nursery habitats can elucidate patterns of productivity in multispecies fisheries. Yellowfin sole (Limanda aspera) and northern rock sole ...(Lepidopsetta polyxystra) co-occur throughout the Bering Sea where they support major fisheries. We examined the diets and foraging ecology of juvenile yellowfin sole and northern rock sole (35–100 mm in standard length) captured along the north side of the Alaska Peninsula and in the Port Moller-Herendeen Bay system, the largest marine embayment in the southeastern Bering Sea. As observed in other parts of their ranges, the diets of both species included polychaetes and amphipods. The primary difference in the diets of these species was that the prey of yellowfin sole were almost exclusively endobenthic and epibenthic invertebrates (>82.7% by weight combined) and the northern rock sole consumed substantial amounts of hyperbenthic mysids and pelagic euphausiids (42% combined). Overall dietary overlap was low (Schoener index SI=0.39), in part due to differences in microhabitat use. At sampling stations where both species co-occurred, dietary overlap was notably higher (SI=0.55). Patterns of functional foraging habits and juvenile niche separation that facilitate coexistence of these species throughout their range were expressed with a novel application of principal components analysis of the abiotic (habitat characteristics) and biotic (consumer traits) factors associated with commonly occurring prey types.
The prayerstone hypothesis, grounded in Southern Paiute oral history, holds that selected incised stone artifacts were votive offerings deliberately emplaced where spiritual power (puha) was known to ...reside, accompanying prayers for personal power and expressing thanks for prayers answered. Proposing significant and long-term linkages between Great Basin incised stones and overarching Shoshonean cosmology, this article explores the prayerstone hypothesis in the context of the 3,500 incised stones documented from the Intermountain West, an assemblage spanning seven states and seven millennia. Employing object itinerary perspectives, it becomes possible to develop ritualized cartographies capable of matching oral Shoshonean traditions with specific geographic indicators. The results demonstrate that many (but not all) such incised stones are consistent with the votive emplacement of prayerstones. Multiple constellations of prayerstone practice operated across the Great Basin for more than 5,000 years and carried forward, without perceptible break, among several (but not all) Numic-speaking populations of the ethnohistoric interval. The diversity and antiquity implied by the prayerstone hypothesis suggest dramatically more complex cultural trajectories than those of Lamb's (1958) widely accepted model of a single, late, and simultaneous Numic spread across the Great Basin. La hipótesis de las piedras votivas, basada en la tradición oral del grupo indígena Paiute del Sur, propone que ciertas piedras adornadas con motivos incisos son ofrendas votivas deliberadamente depositadas en lugares habitados por el poder espiritual (puha). Estos artefactos acompañan las peticiones de poder personal y las acciones de gracias. Este artículo propone que existen importantes relaciones de largo plazo entre las piedras votivas de la Gran Cuenca de Estados Unidos y la cosmología indígena Shoshone. Se explora la hipótesis de las piedras votivas en el contexto de las 3,500 piedras incisas documentadas en el Oeste intermontano --un conjunto que abarca siete estados y siete milenios. Empleando las perspectivas de los itinerarios de objetos es posible desarrollar cartografías ritualizadas que conectan las tradiciones orales Shoshone con indicadores geográficos específicos. Los resultados demuestran que muchas de las piedras incisas (pero no todas) fueron depositadas en contextos votivos. Múltiples constelaciones de práctica que incluyeron las piedras votivas estuvieron en uso a lo largo de la Gran Cuenca por más de 5.000 años y continuaron sin aparente interrupción entre varios grupos lingüísticos Numa (pero no todos) en el período etnohistórico. La antigüedad y diversidad representadas por la hipótesis de las piedras votivas sugieren la existencia de trayectorias culturales mucho más complejas que aquellas sugeridas en el popular modelo de Lamb (1958), quien propuso una única expansión Númica tardía a través de la Gran Cuenca.
Effective and sustainable management depends on knowledge of spawning locations and their relative contributions to marine fish populations. Pacific cod (Gadus macrocephalus) in the southeastern ...Bering Sea aggregate at discrete spawning locations but there is little information on patterns of larval dispersal and the relative contribution of specific spawning areas to nursery habitats. Age-0 Pacific cod from two cohorts (2006 and 2008) were examined to address the following questions: (1) does size, age, and otolith chemistry vary among known capture locations; (2) can variation in elemental composition of the otolith cores (early larval signatures) be used to infer the number of chemically distinct sources contributing to juvenile recruits in the Bering Sea; and (3) to what extent are juvenile collection locations represented by groups of fish with similar chemical histories throughout their early life history? Hierarchical cluster (HCA) and discriminant function analyses (DFA) were used to examine variation in otolith chemistry at discrete periods throughout the early life history. HCA identified five chemically distinct groups of larvae in the 2006 cohort and three groups in 2008; however, three sources accounted for 80–100% of the juveniles in each year. DFA of early larval signatures indicated that there were non-random spatial distributions of early larvae in both years, which may reflect interannual variation in regional oceanography. There was also a detectable and substantial level of coherence in chemical signatures within groups of fish throughout the early life history. The variation in elemental signatures throughout the early life history (hatch to capture) indicates that otolith chemical analysis could be an effective tool to further clarify larval sources and dispersal, identify juvenile nursery habitats, and estimate the contributions of juvenile nursery habitats to the adult population within the southeastern Bering Sea.
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