The world's coral reefs appear to be in a global decline, yet most previous research on coral reefs has taken place at depths shallower than 30 m. Mesophotic coral ecosystem (depths deeper than ~30 ...m) studies have revealed extensive, productive habitats and rich communities. Despite recent advances, mesophotic coral ecosystems remain understudied due to challenges with sampling at deeper depths. The few previous studies of mesophotic coral ecosystems have shown variation across locations in depth-specific species composition and assemblage shifts, potentially a response to differences in habitat or light availability/water clarity. This study utilized scuba to examine fish and benthic communities from shallow and upper mesophotic (to 45 m) zones of Flower Garden Banks National Marine Sanctuary (FGBNMS, 28°0'N; 93°50'W) from 2010-2012. Dominant planktivores were ubiquitous in shallow and upper mesophotic habitats, and comparisons with previous shallow research suggest this community distribution has persisted for over 30 years. Planktivores were abundant in shallow low-relief habitats on the periphery of the coral reef, and some of these sites that contained habitat transitioning from high to low relief supported high biomass of benthic predators. These peripheral sites at FGBNMS may be important for the trophic transfer of oceanic energy to the benthic coral reef. Distinct differences between upper mesophotic and shallow communities were also observed. These included greater overall fish (as well as apex predator) biomass in the upper mesophotic, differences in apex predator community composition between depth zones, and greater percent cover of algae, rubble, sand, and sponges in the upper mesophotic. Greater fish biomass in the upper mesophotic and similar fish community composition between depth zones provide preliminary support that upper mesophotic habitats at FGBNMS have the capacity to serve as refugia for the shallow-water reefs. Diving surveys of the upper mesophotic and shallow-water coral reef have revealed valuable information concerning the reef fish community in the northern Gulf of Mexico, with implications for the conservation of apex predators, oceanic coral reefs, and the future management of FGBNMS.
Many biological processes are coupled to ATP hydrolysis. We describe here a class of closely related ATP-binding proteins, from several bacterial species, which are associated with a variety of ...cellular functions including membrane transport, cell division, nodulation in Rhizobium and haemolysin export. These proteins comprise a family of structurally and functionally related subunits which share a common evolutionary origin, bind ATP and probably serve to couple ATP hydrolysis to each of these biological processes. This finding suggests a specific role for ATP in cell division, nodulation during nitrogen fixation and protein export, and allows us to assign a probable function to one of the protein components from each of these systems.
Abstract Low-risk renal transplant recipients treated with standard immunosuppressive therapy including interleukin-2 receptor (IL-2R) antagonist show a low incidence of early rejection episodes but ...few reports have examined the incidence and severity of late rejection processes. This study evaluated retrospectively cellular and antibody-mediated rejection (AMR) among 42 recipients selected because they showed low panel-reactive-antibodies, short cold ischemia time, no delayed graft function, and therapy including basiliximab (Simulect) induction. The mean observation time was 6.6 years. Sixty-seven percent of donors were deceased. Ten-year patient and death-censored graft survivals were 81% and 78%, respectively. Seven patients lost their kidneys due to nonimmunologic events. The seven recipients who experienced cellular rejection episodes during the first posttransplant year had them reversed with steroids. Five patients displayed late acute AMR causing functional deterioration in four cases including 1 graft loss. De novo sensitization occurred in 48% of recipients including patients without clinical rejection. In conclusion, long-term follow-up of kidney transplant recipients selected by a low immunologic risk showed a persistent risk of de novo sensitization evolving to acute AMR in 11% of cases. Although immunologic events were related to late immunosuppressive reduction, most graft losses were due to nonimmunologic factors.
Bluefish Pomatomus saltatrix have experienced declines in recruitment and adult abundance along the US East Coast since the mid-1980s. At the onset of winter, young-of-the-year (YOY) bluefish exhibit ...a multimodal size distribution including larger, spring-spawned fish (spring cohort) and smaller, summer-spawned fish (summer cohort). Declines in the adult stock appear to coincide with declines in recruitment success of the summer cohort. We investigated the hypothesis that poor recruitment success of the summer cohort results from size-selective winter mortality. Winter mesocosm experiments were conducted to examine the effects of cohort of origin (spring vs. summer) and food availability (fed vs. unfed) on winter survival of YOY bluefish. Spring fish entered winter with significantly greater lipid reserves than summer fish. When fed, both cohorts stored lipids during late fall, depleted lipid reserves during winter, and experienced high overwinter survival. When starved, both cohorts mobilized lipids from multiple depots (liver, viscera, white muscle, red muscle, skin) and summer fish experienced starvation mortality similar to 6 wk prior to spring fish. Although summer fish were more susceptible to winter starvation than spring fish, their starvation endurance (>90% survival probability after 120 d) appeared more than adequate to survive natural winter conditions. Interestingly, spring fish suffered a brief mortality event during January when water temperatures dropped briefly below 6 degree C, suggesting that larger individuals are less tolerant of acute cold stress. The remarkable starvation endurance of summer-spawned bluefish, coupled with their capacity for rapid lipid storage during fall and reduced rates of lipid depletion at low temperatures, implies that members of this cohort are physiologically well-equipped to survive their first winter of life. Our findings are inconsistent with the hypothesis that winter starvation accounts for decreased recruitment of the summer cohort to the western Atlantic stock.
Young-of-the-year (YOY) bluefishPomatomus saltatrixbecome piscivorous at about 40 mm total length, coinciding with a habitat shift from offshore waters to estuarine nursery areas. Although YOY ...bluefish are primarily piscivorous in estuarine waters, shrimp prey can often be an important component of diets in mid-summer. In this study, we first compare the feeding behaviour and prey selection patterns of bluefish feeding on fishMenidia menidiaand sand shrimpCrangon septemspinosaprey in a series of laboratory experiments, and then assess prey-type selectivity in the field. Compared to consuming fish prey, ingesting shrimp prey involved added manipulation and close inspection by the predator. Feeding on shrimp prey resulted in lower attack success rates, longer handling times, and lower relative profitabilities than feeding on fish prey. When given a choice, bluefish selectively ingested fish prey over similarly-sized shrimp prey. The results of these experiments suggest that species-specific differences in prey response lead to the observed differences in predator behaviour and selectivity. Examination of field-collected spring-spawned bluefish showed that their diet was dominated by fishes; however, sand shrimp were important prey in early summer. Selectivity index values showed that bluefish exhibited positive selection for fishes and avoidance of shrimp. The occurrence of shrimp in bluefish diets probably results from high relative abundance of shrimp and the small size of shrimp relative to fish prey. We conclude that the timing of bluefish entry into estuaries relative to peaks in abundance of various prey could have a strong effect on bluefish size at the end of the growing season and, therefore size-dependent survival.
Results from observational studies and randomized clinical trials (RCTs) have led to the consensus that hydroxychloroquine (HCQ) and chloroquine (CQ) are not effective for COVID-19 prevention or ...treatment. Pooling individual participant data, including unanalyzed data from trials terminated early, enables more detailed investigation of the efficacy and safety of HCQ/CQ among subgroups of hospitalized patients.
We searched ClinicalTrials.gov in May and June 2020 for US-based RCTs evaluating HCQ/CQ in hospitalized COVID-19 patients in which the outcomes defined in this study were recorded or could be extrapolated. The primary outcome was a 7-point ordinal scale measured between day 28 and 35 post enrollment; comparisons used proportional odds ratios. Harmonized de-identified data were collected via a common template spreadsheet sent to each principal investigator. The data were analyzed by fitting a prespecified Bayesian ordinal regression model and standardizing the resulting predictions.
Eight of 19 trials met eligibility criteria and agreed to participate. Patient-level data were available from 770 participants (412 HCQ/CQ vs 358 control). Baseline characteristics were similar between groups. We did not find evidence of a difference in COVID-19 ordinal scores between days 28 and 35 post-enrollment in the pooled patient population (odds ratio, 0.97; 95% credible interval, 0.76-1.24; higher favors HCQ/CQ), and found no convincing evidence of meaningful treatment effect heterogeneity among prespecified subgroups. Adverse event and serious adverse event rates were numerically higher with HCQ/CQ vs control (0.39 vs 0.29 and 0.13 vs 0.09 per patient, respectively).
The findings of this individual participant data meta-analysis reinforce those of individual RCTs that HCQ/CQ is not efficacious for treatment of COVID-19 in hospitalized patients.
Ecology Letters (2011) 14: 1288–1299
Predator–prey interactions are a primary structuring force vital to the resilience of marine communities and sustainability of the world’s oceans. Human ...influences on marine ecosystems mediate changes in species interactions. This generality is evinced by the cascading effects of overharvesting top predators on the structure and function of marine ecosystems. It follows that ecological forecasting, ecosystem management, and marine spatial planning require a better understanding of food web relationships. Characterising and scaling predator–prey interactions for use in tactical and strategic tools (i.e. multi‐species management and ecosystem models) are paramount in this effort. Here, we explore what issues are involved and must be considered to advance the use of predator–prey theory in the context of marine fisheries science. We address pertinent contemporary ecological issues including (1) the approaches and complexities of evaluating predator responses in marine systems; (2) the ‘scaling up’ of predator–prey interactions to the population, community, and ecosystem level; (3) the role of predator–prey theory in contemporary fisheries and ecosystem modelling approaches; and (4) directions for the future. Our intent is to point out needed research directions that will improve our understanding of predator–prey interactions in the context of the sustainable marine fisheries and ecosystem management.
Tidal creeks along the southeastern U.S. and Gulf of Mexico coastlines provide nursery habitats for commercially and ecologically important nekton, including juvenile blue crabs Callinectes sapidus, ...a valuable and heavily landed seafood species. Instream and watershed urbanization may influence the habitat value that tidal creeks provide to blue crabs. We investigated natural and anthropogenic factors influencing juvenile blue crab occupancy dynamics in eight first-order tidal creeks in coastal North Carolina (USA). An auto-logistic hierarchical multi-season (dynamic) occupancy model with separate ecological and observation sub-models was fitted to juvenile blue crab presence/absence data collected over replicate sampling visits in multiple seasons at three fixed trapping sites in each creek. Colonization and survival are the processes operating on occupancy that are estimated with this formulation of the model. Covariates considered in the ecological sub-model included watershed imperviousness, the percent of salt marsh in each creek’s high tide area, percent salt marsh edge, site-level water depth, and site-level salinity. Temperature, salinity, and dissolved oxygen were covariates considered in the observation sub-model. In the ecological sub-model, watershed imperviousness was a meaningful negative covariate and site-level salinity was a positive covariate of survival probability. Imperviousness and salinity were each marginally meaningful on colonization probability. Water temperature was a positive covariate of detection probability in the observation sub-model. Mean estimated detection probability across all sites and seasons of the study was 0.186. The results suggest that development in tidal creek watersheds will impact occupancy dynamics of juvenile blue crabs. This places an emphasis on minimizing losses of natural land cover classes in tidal creek watersheds to reduce the negative impacts to populations of this important species. Future research should explore the relationship between imperviousness and salinity fluctuations in tidal creeks to better understand how changing land cover influences water chemistry and ultimately the demographics of juvenile blue crabs.
The ecology of overwintering young-of-the-year bluefish Pomatomus saltatrix off North Carolina, USA, was examined for the 2001 and 2002 year- classes, to test the hypothesis that overwinter mortality ...affects the recruitment of summer-spawned bluefish. A trawling survey was conducted in Onslow Bay, North Carolina, from October 2001 to May 2002 and from September 2002 to June 2003 to determine bluefish abundance, cohort structure, energy density of white muscle and liver, and gut fullness. Up to 4 transects ranging from 0.4 to 16.1 km from shore were sampled monthly. Abundance of bluefish in Onslow Bay was high during the fall and declined with decreasing temperature in both years. Winter abundance was related to winter severity, with higher catches during the more mild winter of 2001 to 2002. At least 3 young-of-the-year cohorts were observed in both years. Gut fullness values generally followed temperature patterns, with reduced feeding during the winter. Energy reserves in white muscle and liver tissues peaked in November with larger fish having disproportionately more energy. However, by mid-winter there was little difference in energy reserves between the cohorts. These data suggest that larger fish deplete a greater portion of their energy stores as the season progresses while smaller fish deplete energy more slowly. Catch data show that summer-spawned bluefish survive the winter, but the magnitude of overwinter mortality remains uncertain.
We conducted a series of size-structured laboratory experiments to quantify and compare the susceptibility of several estuarine and marine forage fishes to attack and capture by piscivorous ...predators. Size-dependent estimates of capture success, handling time, and prey profitability were generated from single-species experiments offering bay anchovy, Atlantic menhaden, Atlantic silverside, and age-0 striped bass to piscivores. Bay anchovy and Atlantic menhaden were most susceptible to capture and yielded high profitability compared to Atlantic silverside and age-0 striped bass prey. Variation in capture success among forage species was particularly influential in generating disparate profitability functions. Although morphological differences among forage species contributed to variation in susceptibility to predation, behavioral analyses indicated that variable reaction distances to approaching predators and activity levels of prey may explain a large fraction of the observed differences in susceptibility. When several forage species were offered to predators simultaneously in larger enclosures, mortality was highest and occurred earlier for bay anchovy and Atlantic menhaden compared to other prey, which points to the strong influence of predator capture success on overall forage fish vulnerability. Our results demonstrate species-specific differences among forage fishes in the ability to avoid attack and capture by piscivores, and we conclude that the expression of antipredator behaviors contributes significantly to variation in forage species vulnerability.
PDF
