High-resolution sampling of particulate organic carbon in a coastal upwelling system

Summertime, wind-driven upwelling off the Oregon coast delivers nutrient rich water to the surface that fuels the autotrophic production of particulate organic carbon (POC). This POC can be transported horizontally by fluid motions and vertically by sinking to the bottom where it can be entrained in the benthic boundary layer (BBL). POC can be transformed during transport by heterotrophic metabolism, thus changing its concentration and composition. To better understand the dynamics of POC within the water column of this highly variable system, we developed a semi-automated filtration system that, when coupled to a towed profiling/sampling vehicle, allowed us to collect POC samples at higher spatial and temporal resolution than previously possible. During late May of 2009 we used this system to collect around 400 POC samples from two cross-shelf transects off the central Oregon coast spanning the ranges between BBL and surface mixed layer, and shelfbreak to shoreline. These samples were collected in conjunction with in-situ measurements of temperature, salinity, chlorophyll fluorescence, optical backscatter, and beam attenuation coefficients. Analyses of both the optical and bulk measurements indicate the presence of three distinct particle pools. The first pool is rich in POC and shows elevated fluorescence and beam-c relative to optical backscatter. The second pool is elevated in both fluorescence and optical backscatter, and is rich in POC relative to beam-c. The third pool is depleted in POC and shows proportionately elevated backscatter. Using variations in the optical properties of these three particle pools, we created multiple POC – beam-c calibrations, which allowed us to derive high-resolution POC distributions within the water column. This derived distribution indicates a decoupling between sediment and carbon in the BBL, and an unanticipated elevation of POC in the mid water column

Changes in serum adipokines during natural extended fasts in female northern elephant seals

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Rzucidlo, C. L., Sperou, E. S., Holser, R. R., Khudyakov, J., Costa, D. P., & Crocker, D. E. Changes in serum adipokines during natural extended fasts in female northern elephant seals. General and Comparative Endocrinology, 308, (2021): 113760, https://doi.org/10.1016/j.ygcen.2021.113760.Adipose tissue is essential to endotherms for thermoregulation and energy storage as well as functioning as an endocrine organ. Adipose derived hormones, or adipokines, regulate metabolism, energy expenditure, reproduction, and immune function in model systems but are less well studied in wildlife. Female northern elephant seals (NES) achieve high adiposity during foraging and then undergo natural fasts up to five weeks long during haul-outs associated with reproduction and molting, resulting in large changes in adipose reserves. We measured circulating levels of four adipokines: leptin, resistin, adiponectin, and kisspeptin-54, in 196 serum samples from female NES at the beginning and end of their breeding and molting fasts. We examined the relationships between these adipokines and life-history stage, adiposity, mass, cortisol, and an immune cytokine involved in the innate immune response interleukin 6 (IL-6). All four adipokines varied with life-history stage. Leptin concentrations were highest at the beginning of the breeding haul-out. Resistin concentrations were higher throughout the breeding haul-out compared to the molt haul-out. Adiponectin concentrations were highest at the beginning of both haul-outs. Kisspeptin-54 concentrations were highest at the end of the breeding haul-out. Leptin, resistin, and adiponectin were associated with measures of body condition, either adiposity, mass, or both. Resistin, adiponectin, and kisspeptin-54 were associated with circulating cortisol concentrations. Resistin was strongly associated with circulating IL-6, a multifunctional cytokine. Adiponectin was associated with glucose concentrations, suggesting a potential role in tissue-specific insulin sensitivity during life-history stages categorized by high adiposity. Increased cortisol concentrations late in lactation were associated with increased kisspeptin-54, suggesting a link to ovulation initiation in NES. This study suggests dramatic changes in circulating adipokines with life-history and body condition that may exert important regulatory roles in NES. The positive relationship between adiponectin and adiposity as well as the lack of a relationship between leptin and kisspeptin-54 differed from model systems. These differences from biomedical model systems suggest the potential for modifications of expression and function of adipose-derived hormones in species that undergo natural changes in adiposity as part of their life-history.This project was supported by a grant from the Office of Naval Research (#N00014-18-1-2822) to DPC and DEC and the Marine Life Joint Industry Program of the IAGOP. We thank the Año Nuevo State Reserve rangers for logistical support

Rheological characterization of jet-cooked Lesquerella fendleri seed gum and cornstarch solutions

Abstract Lesquerella is a potential new seed crop that contains hydroxy fatty acid triglycerides and approximately 15% seed coat gums. The polysaccharide gum of the Lesquerella fendleri seed was isolated and jet-cooked with cornstarch in a series of laboratory experiments to investigate the viscoelastic properties of gum-modified starch solutions. The Lesquerella gum was combined with cornstarch at 1, 5, and 10% levels to produce a jet-cooked and drum dried material with potential application as a thickening or suspension agent. Flow curves were determined for 1% solutions of jet-cooked starch and gum combinations. All materials investigated were biodegradable and exhibited positive thixotropic behavior

Body condition changes at sea: onboard calculation and telemetry of body density in diving animals

This study was supported by grants from the Office of Naval Research N00014-18-1-2822, DoD SERDP contract W912HQ20C0056, IPEV (Institut Paul Emile Victor) under the Antarctic research program 109 (C. Barbraud) and 1201 (C. Gilbert & C. Guinet), and CNES-TOSCA as part of the SNO-MEMO.The ability of marine mammals to accumulate sufficient lipid energy reserves is vital for mammals' survival and successful reproduction. However, long-term monitoring of at-sea changes in body condition, specifically lipid stores, has only been possible in elephant seals performing prolonged drift dives (low-density lipids alter the rates of depth change while drifting). This approach has limited applicability to other species. Using hydrodynamic performance analysis during transit glides, we developed and validated a novel satellite-linked data logger that calculates real-time changes in body density (∝lipid stores). As gliding is ubiquitous amongst divers, the system can assess body condition in a broad array of diving animals. The tag processes high sampling rate depth and three-axis acceleration data to identify 5 s high pitch angle glide segments at depths >100 m. Body density is estimated for each glide using gliding speed and pitch to quantify drag versus buoyancy forces acting on the gliding animal. We used tag data from 24 elephant seals (Mirounga spp.) to validate the onboard calculation of body density relative to drift rate. The new tags relayed body density estimates over 200 days and documented lipid store accumulation during migration with good correspondence between changes in body density and drift rate. Our study provided updated drag coefficient values for gliding (Cd,f = 0.03) and drifting (Cd,s = 0.12) elephant seals, both substantially lower than previous estimates. We also demonstrated post-hoc estimation of the gliding drag coefficient and body density using transmitted data, which is especially useful when drag parameters cannot be estimated with sufficient accuracy before tag deployment. Our method has the potential to advance the field of marine biology by switching the research paradigm from indirectly inferring animal body condition from foraging effort to directly measuring changes in body condition relative to foraging effort, habitat, ecological factors and anthropogenic stressors in the changing oceans. Expanding the method to account for diving air volumes will expand the system's applicability to shallower-diving (<100 m) species, facilitating real-time monitoring of body condition in a broad range of breath-hold divers.Publisher PDFPeer reviewe

First observations of Weddell seals foraging in sponges in Erebus Bay, Antarctica

Attaching cameras to marine mammals allows for first-hand observation of underwater behaviours that may otherwise go unseen. While studying the foraging behaviour of 26 lactating Weddell seals (Leptonychotes weddellii) in Erebus Bay during the austral spring of 2018 and 2019, we witnessed three adults and one pup investigating the cavities of Rossellidae glass sponges, with one seal visibly chewing when she removed her head from the sponge. To our knowledge, this is the first report of such behaviour. While the prey item was not identifiable, some Trematomus fish (a known Weddell seal prey) use glass sponges for shelter and in which to lay their eggs. Three of the four sponge foraging observations occurred around 13:00 (NZDT). Two of the three sponge foraging adults had higher-than-average reproductive rates, and the greatest number of previous pups of any seal in our study population, each having ten pups in 12 years. This is far higher than the study population average of three previous pups (± 2.6 SD). This novel foraging strategy may have evolved in response to changes in prey availability, and could offer an evolutionary advantage to some individuals that exploit prey resources that others may not. Our observations offer new insight into the foraging behaviours of one of the world’s most studied marine mammals. Further research on the social aspects of Weddell seal behaviour may increase our understanding of the extent and mechanisms of behavioural transfer between conspecifics. Research into the specific foraging behaviour of especially successful or experienced breeders is also warranted

Organic carbon content and carbon isotope variations across the Permo-Triassic boundary in the Gartnerkofel-1 borehole, Carnic Alps, Austria

The Gartnerkofel borehole is one of the most thoroughly studied and described Permo-Triassic sections in the world. Detailed bulk organic carbon isotope studies show a negative base shift from − 24‰ to − 28‰ in the Latest Permian which latter value persists into the Earliest Triassic after which it decreases slightly to − 26‰. Two strongly negative peaks of > − 38‰ in the Latest Permian and a lesser peak of − 31‰ in the Early Triassic are too negative to be due to a greater proportion of more negative organic matter and must be due to very negative methane effects. The overall change to more negative values across the Bulla/Tesero boundary fits the relative rise in sea level for this transition based on the facies changes. A positive shift in organic carbon isotope values at the Late Permian Event Horizon may be due to an increase in land-derived organic detritus at this level—a feature shown by all Tethyan Permo-Triassic boundary sections though these other sections do not have the same values. Carbonate carbon isotope trends are similar in all sections dropping by 2–3 units across the Permo-Triassic boundary. Gartnerkofel carbonate oxygen values are surprisingly, considering the ubiquitous dolomitization, compatible with values elsewhere and indicate reasonable tropical temperatures of 60 °C in the Latest Permian sabkhas to 20–40 °C in the overlying marine transition beds. Increased land-derived input at the Late Permian Event Horizon may be due to offshore transport by tsunamis whose deposits have been recognized in India at this level

Geochemical response of the mid-depth Northeast Atlantic Ocean to freshwater input during Heinrich events 1 to 4

PublishedArticleHeinrich events are intervals of rapid iceberg-sourced freshwater release to the high latitude North Atlantic Ocean that punctuate late Pleistocene glacials. Delivery of fresh water to the main North Atlantic sites of deep water formation during Heinrich events may result in major disruption to the Atlantic Meridional Overturning Circulation (AMOC), however, the simple concept of an AMOC shutdown in response to each freshwater input has recently been shown to be overly simplistic. Here we present a new multi-proxy dataset spanning the last 41,000 years that resolves four Heinrich events at a classic mid-depth North Atlantic drill site, employing four independent geochemical tracers of water mass properties: boron/calcium, carbon and oxygen isotopes in foraminiferal calcite and neodymium isotopes in multiple substrates. We also report rare earth element distributions to investigate the fidelity by which neodymium isotopes record changes in water mass distribution in the northeast North Atlantic. Our data reveal distinct geochemical signatures for each Heinrich event, suggesting that the sites of fresh water delivery and/or rates of input played at least as important a role as the stage of the glacial cycle in which the fresh water was released. At no time during the last 41 kyr was the mid-depth northeast North Atlantic dominantly ventilated by southern-sourced water. Instead, we document persistent ventilation by Glacial North Atlantic Intermediate Water (GNAIW), albeit with variable properties signifying changes in supply from multiple contributing northern sources.This research used samples provided by the Integrated Ocean Drilling (Discovery) Program IODP, which is sponsored by the US National Science Foundation and participating countries under management of Joint Oceanographic Institutions, Inc. We thank Walter Hale and Alex Wülbers for help with sampling, Kirsty Crocket for providing additional samples and Matt Cooper, Andy Milton, Mike Bolshaw and Dave Spanner for analytical support. Heiko Pälike, David Thornalley and Rachel Mills are thanked for productive discussions and comments on earlier versions of this work. We also thank three anonymous reviewers for their constructive feedback, which greatly improved the manuscript. Funding for this project was provided by NERC studentships to A.J.C. (grant NE/D005728/2) and T.B.C. (NE/I528626/1), with additional funding support from a Royal Society Wolfson Research Merit Award and NERC grants NE/F00141X/1 and NE/I006168/1 to P.A.W. and NE/D00876X/2 to G.L.F