Assessment of Calanus finmarchicus growth and dormancy using the aminoacyl-tRNA synthetases method

first_imgWe obtained growth rates of the copepod Calanus finmarchicus at different locations across the North Atlantic between May 1998 and June 2004. Animals were incubated for 2–9 days and fed either with natural food assemblages or with cultured algae. During this period, we measured both somatic weight-specific growth rates (measured as protein change) and aminoacyl-tRNA synthetases (AARS) activity. We found a highly significant relationship between AARS activity and growth in protein content (R2 = 0.55, P < 0.001). Significant AARS activity also occurred when growth was negative, the relationship predicting an AARS activity level of 8.33 nmPPi·mg protein–1·h–1 when somatic growth is zero. This is because AARS activity is expected even when growth is negative, owing to the continued protein turnover in the cells. The AARS method allowed for the first time the study of protein metabolism in overwintering C. finmarchicus. Our study results showed that overwintering copepods had significantly lower values of AARS activity than non-diapausing animals (t = –3.51, P < 0.002). The AARS method opens the possibility to better understand physiology dynamics of deep-water organisms (e.g. the beginning and end of diapause).last_img read more

Climatically driven fluctuations in Southern Ocean ecosystems

first_imgDetermining how climate fluctuations affect ocean ecosystems requires an understanding of how biologicaland physical processes interact across a wide range of scales. Here we examine the role of physical andbiological processes in generating fluctuations in the ecosystem around South Georgia in the SouthAtlantic sector of the Southern Ocean. Anomalies in sea surface temperature (SST) in the South Pacificsector of the Southern Ocean have previously been shown to be generated through atmosphericteleconnections with El Nin˜o Southern Oscillation (ENSO)-related processes. These SST anomalies arepropagated via the Antarctic Circumpolar Current into the South Atlantic (on time scales of more than1 year), where ENSO and Southern Annular Mode-related atmospheric processes have a direct influenceon short (less than six months) time scales.We find that across the South Atlantic sector, these changes inSST, and related fluctuations in winter sea ice extent, affect the recruitment and dispersal of Antarctic krill.This oceanographically driven variation in krill population dynamics and abundance in turn affects thebreeding success of seabird and marine mammal predators that depend on krill as food. Such propagatinganomalies, mediated through physical and trophic interactions, are likely to be an important component ofvariation in ocean ecosystems and affect responses to longer term change. Population models derived onthe basis of these oceanic fluctuations indicate that plausible rates of regional warming of 1oC over the next100 years could lead to more than a 95% reduction in the biomass and abundance of krill across the ScotiaSea by the end of the century.last_img read more

Responses of plants in polar regions to UVB exposure: a meta-analysis

first_imgWe report a meta-analysis of data from 34 field studies into the effects of ultraviolet B (UVB) radiation on Arctic and Antarctic bryophytes and angiosperms. The studies measured plant responses to decreases in UVB radiation under screens, natural fluctuations in UVB irradiance or increases in UVB radiation applied from fluorescent UV lamps. Exposure to UVB radiation was found to increase the concentrations of UVB absorbing compounds in leaves or thalli by 7% and 25% ( expressed on a mass or area basis, respectively). UVB exposure also reduced aboveground biomass and plant height by 15% and 10%, respectively, and increased DNA damage by 90%. No effects of UVB exposure were found on carotenoid or chlorophyll concentrations, net photosynthesis, F-v/F-m or Phi(PSII), belowground or total biomass, leaf mass, leaf area or specific leaf area (SLA). The methodology adopted influenced the concentration of UVB absorbing compounds, with screens and natural fluctuations promoting significant changes in the concentrations of these pigments, but lamps failing to elicit a response. Greater reductions in leaf area and SLA, and greater increases in concentrations of carotenoids, were found in experiments based in Antarctica than in those in the Arctic. Bryophytes typically responded in the same way as angiosperms to UVB exposure. Regression analyses indicated that the percentage difference in UVB dose between treatment and control plots was positively associated with concentrations of UVB absorbing compounds and carotenoids, and negatively so with aboveground biomass and leaf area. We conclude that, despite being dominated by bryophytes, the vegetation of polar regions responds to UVB exposure in a similar way to higher plant-dominated vegetation at lower latitudes. In broad terms, the exposure of plants in these regions to UVB radiation elicits the synthesis of UVB absorbing compounds, reduces aboveground biomass and height, and increases DNA damage.last_img read more

Variability among individuals is generated at the gene expression level

first_imgSelection acts on individuals, specifically on their differences. To understand adaptation and responses to change therefore requires knowledge of how variation is generated and distributed across traits. Variation occurs on different biological scales, from genetic through physiological to morphological, yet it is unclear which of these carries the most variability. For example, if individual variation is mainly generated by differences in gene expression, variability should decrease progressively from coding genes to morphological traits, whereas if post translational and epigenetic effects increase variation, the opposite should occur. To test these predictions, we compared levels of variation among individuals in various measures of gene expression, physiology (including activity) and morphology in two abundant and geographically widespread Antarctic molluscs, the clam Laternula elliptica and the limpet Nacella concinna. Direct comparisons among traits as diverse as heat shock protein QPCR assays, whole transcription profiles, respiration rates, burying rate, shell length and ash-free dry mass were made possible through the novel application of an established metric, the Wentworth Scale. In principle, this approach could be extended to analyses of populations, communities or even entire ecosystems. We found consistently greater variation in gene expression than morphology, with physiological measures falling in between. This suggests that variability is generated at the gene expression level. These findings have important implications for refining current biological models and predictions of how biodiversity may respond to climate change.last_img read more

Demonstration of “substantial research activity” to acquire consultative status under the Antarctic Treaty

first_imgAntarctic Treaty Consultative Parties are entitled to participate in consensus-based governance of the continent through the annual Antarctic Treaty Consultative Meetings. To acquire consultative status, an interested Party must demonstrate “substantial research activity,” but no agreed mechanism exists to determine whether a Party has fulfilled this criterion. Parties have generally demonstrated substantial research activity with the construction of a research station, as suggested within the Treaty itself. However, this largely demonstrates logistical capacity, rather than research activity, and often results in major and persistent impacts on Antarctic terrestrial environments. Our study found that national investment in Antarctic infrastructure, estimated by the number of bed spaces at stations, was not a reliable indicator of scientific output. Therefore, we investigated metrics to evaluate research activity directly, and identified both the overall number of Antarctic papers and the proportion of national scientific output these represented as meaningful metrics. Such metrics could (1) demonstrate a nation’s level of research activity in Antarctica or (2) help Consultative Parties assess the level of research activity undertaken by a Party seeking to acquire consultative status. Our data showed that, even without land-based Antarctic infrastructure, Canada, Denmark and Switzerland may have reasonable grounds to demonstrate “substantial research activity” on a level comparable with existing Consultative Parties. The use of these metrics may help dispel any perceived requirement for the establishment of a research station to reach consultative status, by putting a greater emphasis on generation of scientific research outputs rather than construction of Antarctic infrastructure.last_img read more

The winter pack-ice zone provides a sheltered but food-poor habitat for larval Antarctic krill

first_imgA dominant Antarctic ecological paradigm suggests that winter sea ice is generally the main feeding ground for krill larvae. Observations from our winter cruise to the southwest Atlantic sector of the Southern Ocean contradict this view and present the first evidence that the pack-ice zone is a food-poor habitat for larval development. In contrast, the more open marginal ice zone provides a more favourable food environment for high larval krill growth rates. We found that complex under-ice habitats are, however, vital for larval krill when water column productivity is limited by light, by providing structures that offer protection from predators and to collect organic material released from the ice. The larvae feed on this sparse ice-associated food during the day. After sunset, they migrate into the water below the ice (upper 20 m) and drift away from the ice areas where they have previously fed. Model analyses indicate that this behaviour increases both food uptake in a patchy food environment and the likelihood of overwinter transport to areas where feeding conditions are more favourable in spring.last_img read more

The global diabatic circulation of the stratosphere as a metric for the Brewer–Dobson circulation

first_imgThe circulation of the stratosphere, also known as the Brewer–Dobson circulation, transports water vapor and ozone, with implications for radiative forcing and climate. This circulation is typically quantified from model output by calculating the tropical upwelling vertical velocity in the residual circulation framework, and it is estimated from observations by using time series of tropical water vapor to infer a vertical velocity. Recent theory has introduced a method to calculate the strength of the global mean diabatic circulation through isentropes from satellite measurements of long-lived tracers. In this paper, we explore this global diabatic circulation as it relates to the residual circulation vertical velocity, stratospheric water vapor, and ozone at interannual timescales. We use a comprehensive climate model, three reanalysis data products, and satellite ozone data. The different metrics for the circulation have different properties, especially with regards to the vertical autocorrelation. In the model, the different residual circulation metrics agree closely and are well correlated with the global diabatic circulation, except in the lowermost stratosphere. In the reanalysis products, however, there are more differences throughout, indicating the dynamical inconsistencies of these products. The vertical velocity derived from the time series of water vapor in the tropics is significantly correlated with the global diabatic circulation, but this relationship is not as strong as that between the global diabatic circulation and the residual circulation vertical velocity. We find that the global diabatic circulation in the lower to middle stratosphere (up to 500 K) is correlated with the total column ozone in the high latitudes and in the tropics. The upper-level circulation is also correlated with the total column ozone, primarily in the subtropics, and we show that this is due to the correlation of both the circulation and the ozone with upper-level temperatures.last_img read more

First direct observation of sea salt aerosol production from blowing snow above sea ice

first_imgTwo consecutive cruises in the Weddell Sea, Antarctica, in winter 2013 provided the first direct observations of sea salt aerosol (SSA) production from blowing snow above sea ice, thereby validating a model hypothesis to account for winter time SSA maxima in polar regions not explained otherwise. Blowing or drifting snow always lead to increases in SSA during and after storms. Observed aerosol gradients suggest that net production of SSA takes place near the top of the blowing or drifting snow layer. The observed relative increase of SSA concentrations with wind speed suggests that on average the corresponding aerosol mass flux during storms was equal or larger above sea ice than above the open ocean, demonstrating the importance of the blowing snow source for SSA in winter and early spring. For the first time it is shown that snow on sea ice is depleted in sulphate relative to sodium with respect to sea water. Similar depletion observed in the aerosol suggests that most sea salt originated from snow on sea ice and not the open ocean or leads, e.g. on average 93 % during the 8 June and 12 August 2013 period. A mass budget calculation shows that sublimation of snow even with low salinity (< 1 psu) can account for observed increases of atmospheric sea salt from blowing snow. Furthermore, snow on sea ice and blowing snow showed no or small depletion of bromide relative to sodium with respect to sea water, whereas aerosol at 29 m was enriched suggesting that SSA from blowing snow is a source of atmospheric reactive bromine, an important ozone sink, with bromine loss taking place preferentially in the aerosol phase between 2 and 29 m above the sea ice surface. Evaluation of the current model for SSA production from blowing snow showed that the parameterisations used can generally be applied to snow on sea ice. Snow salinity, a sensitive model parameter, depends to a first order on snowpack depth and therefore is higher above first-year than above multi-year sea ice. Shifts in the ratio of FYI and MYI over time are therefore expected to change the seasonal SSA source flux and contribute to the variability of SSA in ice cores, which both represents an opportunity and a challenge for the quantitative interpretation of the sea salt sea ice proxy. It is expected that similar processes take place in the Arctic regions.last_img read more

The influence of glacial melt and retreat on the nutritional condition of the bivalve Nuculana inaequisculpta (Protobranchia: Nuculanidae) in the West Antarctic Peninsula

first_imgDue to climate change, numerous ice bodies have been lost in the West Antarctic Peninsula (WAP). As a consequence, deglaciation is expected to impact the marine environment and its biota at physiological and ecosystem levels. Nuculana inaequisculpta is a marine bivalve widely distributed around Antarctica that plays an important role for ecosystem functioning. Considering that N. inaequisculpta inhabits coastal areas under effect of glacial melt and retreat, impacts on its nutritional condition are expected due to alterations on its physiology and food availability. To test this hypothesis, biochemical composition (lipids, proteins, and fatty acids) and energy content were measured in individuals of N. inaequisculpta collected in a fjord at different distances to the retreating glacier in the WAP. Oceanographic parameters of the top and bottom-water layers (temperature, salinity, dissolved oxygen, and chlorophyll-a) were measured to investigate how the environment changes along the fjord. Results showed that surface oceanographic parameters displayed a lower temperature and dissolved oxygen, but a higher salinity and chlorophyll-a content at nearest compared to farthest sites to the glacier. In contrast, a lower temperature and chlorophyll-a, and a higher salinity and dissolved oxygen was measured in the bottom-water layer toward the glacier. N. inaequisculpta had a higher amount of lipids (17.42 ± 3.24 vs. 12.16 ± 3.46%), protein (24.34 ± 6.12 vs. 21.05 ± 2.46%) and energy content (50.57 ± 6.97 J vs. 39.14 ± 5.80 J) in the farthest compared to the nearest site to the glacier. No differences were found in total fatty acids among all sites. It seems likely that lower individual fitness related to proximity to the glacier would not be related to nutritional quality of sediment food, but rather to food quantity.last_img read more

UVU Wrestling Finalizes Sizable 2018 Recruiting Class

first_img Tags: Cameron Haddock/Chase Trussell/Greg Williams/Isaiah Delgado/Jaron Chavez/Jason Gissel/Jayden Woodruff/Jerry Rubio/Josh Tolentino/Josiah Nava/Kainalu “Skip” Estrella/Nick Rino/Paul Frampton/Taten Ringel/UVU Wrestling/William Edelblute Brad James June 15, 2018 /Sports News – Local UVU Wrestling Finalizes Sizable 2018 Recruiting Class FacebookTwitterLinkedInEmailOREM, Utah-Friday, the Utah Valley University wrestling program finalized its massive recruiting class, which consists of 16 student-athletes.Although the Wolverines have the distinction of being Utah’s only collegiate wrestling program, the recruits hail from nine states in this class.Head Coach Greg Williams stated he is proud of this class, saying “These student-athletes are all serious about performing well and keeping up with our recent success in the classroom.”Two of Williams’ recruits are college transfers as Jaron Chavez comes from Division I Cornell and Dayton Racer enters the program from Clackamas CC of Oregon City, Ore.The rest of the class comes from high school, including three from Utah: Tanner Lofthouse of Mountain Crest High School, Taten Ringel from North Summit High School and Chase Trussell from Morgan High School.The others are Californian products Jerry Rubio (Carter H.S.) and Josh Tolentino (Poway H.S.), Coloradans Josiah Nava (Pueblo Country H.S.) and Jayden Woodruff (Ponderosa H.S.), Idahoans William Edelblute (Lakeland Senior H.S.) and Jason Gissel (Fruitland H.S.), Texans Cameron Haddock (Carroll Senior H.S.) and Isaiah Delgado (Eastwood H.S. of El Paso, Texas) and one each from Hawaii (Kainalu “Skip” Estrella of Lahainaluna H.S.), New Mexico (Nick Rino of Piedra Vista H.S.) and West Virginia (Paul Frampton, Nitro H.S.).The majority of these newcomers will join the Wolverines’ active roster in 2018-19, although Ringel has confirmed he plans to serve an LDS Church mission before competing for UVU. Written bylast_img read more