Trophic interactions of Bathyraja trachura and sympatric fishes

Quantifying deep-sea food webs can be resource intensive due to the difficulties of sampling fishes from the deep sea. The diet of fishes is often quantified through stomach content analysis, through this method has many sampling constraints, and it can be difficult to obtain sufficient samples for an in-depth study. This study attempts to fill a critical data gap by determining the diet and trophic level of the deep-sea Roughtail Skate, Bathyraja trachura, using traditional stomach content analysis. This study also attempts to determine the validity and accuracy of stable isotope analysis in the continental slope fishes of the deep-sea of the eastern North Pacific, as an alternative method to determine trophic level in fishes. The Roughtail Skate is an abundant deep-sea skate in the eastern North Pacific. Little is known about the diet of this skate, which is landed as by-catch in commercial bottom trawls. Skates were collected between 2005 and 2008 from fishery-independent trawl surveys of the continental slope and outer shelf. Geometric Index of Importance (GII) values indicated that crustaceans (71.4%), fishes (17.8%), polychaetes (4.3%), and cephalopods (3.7%) were the most important prey groups in the diet. Diet differed significantly with total length, but not with sex. Larger individuals (by total length) had significantly higher trophic level values, and year and latitude explained variation in the diet for three prey categories. In this study, fishes and invertebrates collected from the continental slope (1,000 m depth) of the eastern North Pacific were analyzed using stable isotope analysis (SIA). The carbon and nitrogen stable isotope results were used to construct dual isotope plots to investigate the trophic relationships of this deep-sea community. The plots indicated a decoupling of the benthic and pelagic food webs, with the benthic food web being isotopically enriched. Stomach and isotope samples were collected from 32 Roughtail Skates (Bathyraja trachura) to determine the validity and accuracy of SIA in determining the trophic levels of the skates. A linear regression analysis indicated that nitrogen values from SIA and trophic levels calculated from stomach content analysis, when plotted against skate total length, exhibited similar variation and patterns, although only the stomach content analysis yielded significant results (stomach content: p=0.020, r2=0.168; stable isotope: p=0.077, r2=0.101)

A global perspective on the trophic geography of sharks

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.This research was conducted as part of C.S.B.’s Ph.D dissertation, which was funded by the University of Southampton and NERC (NE/L50161X/1), and through a NERC Grant-in-Kind from the Life Sciences Mass Spectrometry Facility (LSMSF; EK267-03/16). We thank A. Bates, D. Sims, F. Neat, R. McGill and J. Newton for their analytical contributions and comments on the manuscripts.Peer reviewe

Trophic Interactions of Bathyraja trachura and Sympatric Fishes

Quantifying deep-sea food webs can be resource intensive due to the difficulties of sampling fishes from the deep sea. The diet of fishes is often quantified through stomach content analysis, through this method has many sampling constraints, and it can be difficult to obtain sufficient samples for an in-depth study. This study attempts to fill a critical data gap by determining the diet and trophic level of the deep-sea Roughtail Skate, Bathyraja trachura, using traditional stomach content analysis. This study also attempts to determine the validity and accuracy of stable isotope analysis in the continental slope fishes of the deep-sea of the eastern North Pacific, as an alternative method to determine trophic level in fishes.The Roughtail Skate is an abundant deep-sea skate in the eastern North Pacific. Little is known about the diet of this skate, which is landed as by-catch in commercial bottom trawls. Skates were collected between 2005 and 2008 from fishery-independent trawl surveys of the continental slope and outer shelf. Geometric Index of Importance (GII) values indicated that crustaceans (71.4%), fishes (17.8%), polychaetes (4.3%), and cephalopods (3.7%) were the most important prey groups in the diet. Diet differed significantly with total length, but not with sex. Larger individuals (by total length) had significantly higher trophic level values, and year and latitude explained variation in the diet for three prey categories.In this study, fishes and invertebrates collected from the continental slope (1,000 m depth) of the eastern North Pacific were analyzed using stable isotope analysis (SIA). The carbon and nitrogen stable isotope results were used to construct dual isotope plots to investigate the trophic relationships of this deep-sea community. The plots indicated a decoupling of the benthic and pelagic food webs, with the benthic food web being isotopically enriched. Stomach and isotope samples were collected from 32 Roughtail Skates (Bathyraja trachura) to determine the validity and accuracy of SIA in determining the trophic levels of the skates. A linear regression analysis indicated that nitrogen values from SIA and trophic levels calculated from stomach content analysis, when plotted against skate total length, exhibited similar variation and patterns, although only the stomach content analysis yielded significant results (stomach content: p=0.020, r2=0.168; stable isotope: p=0.077, r2=0.101)

Dust the body in the landscape

This thesis discusses eight large charcoal drawings exhibited in the Masters of Fine Arts Exhibition on display April 6 to May 5, 2012 at the Washington State University Museum of Art. In this document, there are four sections that relate to the body in the landscape: All Over, Women Artists and Abstraction, Women and the Earth, and the Natural World

Virtual Model of a Street Intersection within the Blue Mile Corridor in Statesboro, Georgia

In fall 2017, a group of graduate and undergraduate students generated a large, 3D, laser-based, point-cloud model of a selected street intersection (South Main St. and Tillman Rd.) in Statesboro, GA. This was accomplished as a service-learning project for the Blue Mile Group and the City of Statesboro. The purpose of the project was to assist the referred group and city engineers, or their designees, in the redesign of this street segment, as part of the revitalization of Downtown Statesboro. To assure the engineers are receiving an accurate model, a measurement comparison analysis was conducted between the finalized virtual model and actual field distances captured with a more traditional and accurate surveying instrument. The model was also geo-referenced in the Georgia East State Plane Coordinate System. By performing these tasks, the authors fully learned the operation of advanced technology to solve real problems affecting the community at their university town

A global perspective on the trophic geography of sharks

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches

A global perspective on the trophic geography of sharks

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches

A global perspective on the trophic geography of sharks

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches

Characteristics and Outcomes of Individuals With Pre-existing Kidney Disease and COVID-19 Admitted to Intensive Care Units in the United States

Rationale & objectiveUnderlying kidney disease is an emerging risk factor for more severe coronavirus disease 2019 (COVID-19) illness. We examined the clinical courses of critically ill COVID-19 patients with and without pre-existing chronic kidney disease (CKD) and investigated the association between the degree of underlying kidney disease and in-hospital outcomes.Study designRetrospective cohort study.Settings & participants4,264 critically ill patients with COVID-19 (143 patients with pre-existing kidney failure receiving maintenance dialysis; 521 patients with pre-existing non-dialysis-dependent CKD; and 3,600 patients without pre-existing CKD) admitted to intensive care units (ICUs) at 68 hospitals across the United States.Predictor(s)Presence (vs absence) of pre-existing kidney disease.Outcome(s)In-hospital mortality (primary); respiratory failure, shock, ventricular arrhythmia/cardiac arrest, thromboembolic events, major bleeds, and acute liver injury (secondary).Analytical approachWe used standardized differences to compare patient characteristics (values>0.10 indicate a meaningful difference between groups) and multivariable-adjusted Fine and Gray survival models to examine outcome associations.ResultsDialysis patients had a shorter time from symptom onset to ICU admission compared to other groups (median of 4 [IQR, 2-9] days for maintenance dialysis patients; 7 [IQR, 3-10] days for non-dialysis-dependent CKD patients; and 7 [IQR, 4-10] days for patients without pre-existing CKD). More dialysis patients (25%) reported altered mental status than those with non-dialysis-dependent CKD (20%; standardized difference=0.12) and those without pre-existing CKD (12%; standardized difference=0.36). Half of dialysis and non-dialysis-dependent CKD patients died within 28 days of ICU admission versus 35% of patients without pre-existing CKD. Compared to patients without pre-existing CKD, dialysis patients had higher risk for 28-day in-hospital death (adjusted HR, 1.41 [95% CI, 1.09-1.81]), while patients with non-dialysis-dependent CKD had an intermediate risk (adjusted HR, 1.25 [95% CI, 1.08-1.44]).LimitationsPotential residual confounding.ConclusionsFindings highlight the high mortality of individuals with underlying kidney disease and severe COVID-19, underscoring the importance of identifying safe and effective COVID-19 therapies in this vulnerable population