C. Choy results 51
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Measurements of pelagic animal biomass exhibit depth-specific bias when trawl volumes are estimated without a flowmeterNARA Subscribed
In open ocean systems, trawling with nets remains one of the most common methods for measuring animal biomass in a volume of seawater, calculated as distance traveled multiplied by net mouth area. The effective distance traveled by the net can be measured using a flowmeter, but in the absence of a flowmeter is often estimated as the distance traveled by the trawling vessel. Studies that do not use a flowmeter to quantify trawl...
Effects of Body Size and Environmental Region on the Nutritional Value of Small Pelagic Species in the California CurrentNARA Subscribed
We evaluated the effects of regional environment and body size on the nutritional traits of five small pelagic species differing in habitat use, feeding behavior, and importance as prey for top predators in the California Current Large Marine Ecosystem (CCLME). Northern anchovy ( Engraulis mordax ), bigfin lanternfish ( Symbolophorus californiensis ), market squid ( Doryteuthis opalescens ), and boreal clubhook squid ( Onychot...
Herein, we report the second known specimen of the one‐jaw eel, Monognathus jesse , collected in 4200 m of water, between 1748 and 2001 m depth, in the northeastern Pacific. This specimen is the second‐largest identified monognathid specimen reported, with a total length of 154 mm unpreserved. A morphological description, comparison to the much smaller holotype and similar species, a micro‐computed tomography scan, and mitocho...
Using stable isotopes to describe the trophic structure of gelatinous zooplankton across the deep pelagicNARA Subscribed
Although gelatinous zooplankton are key members of marine ecosystems and food webs, their trophic ecology is poorly described across the deep pelagic. We used stable carbon (bulk tissue) and nitrogen (bulk tissue and amino acid) isotope analysis to estimate the trophic positions (TPs) of abundant gelatinous zooplankton (chaetognaths, cnidarians, ctenophores, mollusks, pelagic tunicates) across depth habitats. We collected gela...
Gelatinous zooplankton are increasingly recognized as key components of pelagic ecosystems, and there have been many recent insights into their ecology and roles in food webs. To examine the trophic ecology of siphonophores (Cnidaria, Hydrozoa), we used bulk (carbon and nitrogen) and compound‐specific (nitrogen) isotope analysis of individual amino acids (CSIA‐AA). We collected samples of 15 siphonophore genera using blue‐wate...
Open habitats increase vulnerability of amphibian tadpoles to climate warming across latitudeNARA Subscribed
Aim Global warming and deforestation are pushing species closer to their physiological limit, especially for species with habitat‐restricted life stages because sunlit areas have higher maximum temperatures. Here, we examined the critical thermal maximum (CT max ), and maximum environmental water temperature (T max ) of larvae from 29 anuran species across a latitudinal gradient (22–43° N) to test how latitude and habitat type...
We quantified cephalopods consumed by longnose lancetfish ( Alepisaurus ferox , n = 1267 stomachs containing cephalopod remains) from 2009 to 2018 in the central North Pacific Ocean (between 0–35° N and 135–175° W). When cephalopods identified from beak remains in the stomach contents were included in diet analyses, clear increases in the abundance of gelatinous taxa and the inferred foraging depths of lancetfish were evident....
Prolonging survival in good health is a fundamental societal goal. However, the leading determinants of disability-free survival in healthy older people have not been well established. Data from ASPREE, a bi-national placebo-controlled trial of aspirin with 4.7 years median follow-up, was analysed. At enrolment, participants were healthy and without prior cardiovascular events, dementia or persistent physical disability. Disab...
Our perception of deep-sea communities has evolved as various sampling approaches have captured different components of deep-sea habitats. We sampled midwater zooplankton assemblages in Monterey Bay, California to quantify community composition (abundance and biomass) and biodiversity (at the Order level) across three depth ranges, and the effects of sampling methodology on community parameters. We collected zooplankton using...
Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (δ 15 N) are primarily used to estimate trophic position while carbon isotopes (δ 13 C) describe habitat associations and feeding pathways. Models of...
Trends in tuna carbon isotopes suggest global changes in pelagic phytoplankton communitiesNARA Subscribed
Considerable uncertainty remains over how increasing atmospheric CO 2 and anthropogenic climate changes are affecting open‐ocean marine ecosystems from phytoplankton to top predators. Biological time series data are thus urgently needed for the world's oceans. Here, we use the carbon stable isotope composition of tuna to provide a first insight into the existence of global trends in complex ecosystem dynamics and changes in th...
Many species of micronekton perform diel vertical migrations (DVMs), which ultimately contributes to carbon export to the deep sea. However, not all micronekton species perform DVM, and the nonmigrators, which are often understudied, have different energetic requirements that might be reflected in their trophic ecology. We analyze bulk tissue and whole animal stable nitrogen isotopic compositions ( δ 15 N values) of micronekto...
Aim We examined potential environmental drivers of broad‐scale spatial patterns in the trophic structure of marine ecosystems as represented by nitrogen stable isotopes in globally distributed marine predators. Additionally, we assessed the effects of spatial scale on the predictive capabilities of environmental variables. Location Global oceans. Time period 2000 to 2015. Major taxa studied Tunas: Thunnus albacares , Thunnus o...
Several studies have found that the respiratory demand for carbon by the mesopelagic community exceeds carbon supply through the particulate sinking flux by up to two to three orders of magnitude, suggesting that mesopelagic communities rely on additional overlooked carbon sources. Suspended particles (defined as 0.7–53 μ m) have been suggested as one of these sources but few studies have evaluated their contribution to the me...
We used bulk tissue δ 13 C and δ 15 N values and δ 15 N values of individual amino acids (AA) to characterize the trophic structure of a pelagic fish assemblage from the North Pacific Subtropical Gyre (NPSG) ecosystem. We focus on energy flow between fishes inhabiting distinct epipelagic, mesopelagic, and upper bathypelagic habitats and on predatory fish foraging across and within these depth habitats. Trophic positions (TPs)...