THE PRINCE EDWARD ISLANDS' LIFE-SUPPORT SYSTEM: RELATIVE IMPORTANCE OF LOCAL AND ADVECTED SOURCES // Ученые записки КФУ. Естественные науки 2009 N2

За последние 30 лет было описано несколько механизмов объясняющих динамику планктона, а также обеспечение пищей островных хищников и донных сообществ в районе островов Принца Эдуарда. Предложенные механизмы включают: (а) гипотезу апвеллинга с подветренной стороны островной системы, (б) вторжение меандров образованных выше по течению на островной шельф, (в) формирование условий для цветения фитопланктона на островном шельфе, (г) гипотеза «конвейера» доставляющего планктон на шельф островов, и (д) утилизация хищниками фронтальных систем и топографически генерируемых круговоротов выше по течению или в непосредственной близости к островам. Предполагается, что «система жизнеобеспечения» островов Принца Эдуарда включает в себя все перечисленные выше компоненты. Их важность критически рассмотрена и оценена в связи с изменчивостью внешней среды вокруг островов. Базируясь на недавних исследованиях с использованием стабильных изотопов, количественно оценена важность аллохтонных (внешних) и автохтонных (локальных) источников энергии в различных экосистемах островов Принца Эдуарда. В частности, впервые для экосистемы островов показана важность органики поступающей от прибрежных бурых водорослей ламинари

Temporal and spatial variability in stable isotope ratios of SPM link to local hydrography and longer term SPM averages suggest heavy dependence of mussels on nearshore production

Temporal changes in hydrography affect suspended particulate matter (SPM) composition and distribution in coastal systems, potentially influencing the diets of suspension feeders. Temporal variation in SPM and in the diet of the mussel Perna perna, were investigated using stable isotope analysis. The δ13C and δ15 N ratios of SPM, mussels and macroalgae were determined monthly, with SPM samples collected along a 10 km onshore–offshore transect, over 14 months at Kenton-on-Sea, on the south coast of South Africa. Clear nearshore (0 km) to offshore (10 km) carbon depletion gradients were seen in SPM during all months and extended for 50 km offshore on one occasion. Carbon enrichment of coastal SPM in winter (June–August 2004 and May 2005) indicated temporal changes in the nearshore detrital pool, presumably reflecting changes in macroalgal detritus, linked to local changes in coastal hydrography and algal seasonality. Nitrogen patterns were less clear, with SPM enrichment seen between July and October 2004 from 0 to 10 km. Nearshore SPM demonstrated cyclical patterns in carbon over 24-h periods that correlated closely with tidal cycles and mussel carbon signatures, sampled monthly, demonstrated fluctuations that could not be correlated to seasonal or monthly changes in SPM. Macroalgae showed extreme variability in isotopic signatures, with no discernable patterns. IsoSource mixing models indicated over 50% reliance of mussel tissue on nearshore carbon, highlighting the importance of nearshore SPM in mussel diet. Overall, carbon variation in SPM at both large and small temporal scales can be related to hydrographic processes, but is masked in mussels by long-term isotope integration

Causes and consequences of the spatial and temporal distribution of encrusting algae on tropical rocky shores

published_or_final_versionEcology and BiodiversityDoctoralDoctor of Philosoph

THE PRINCE EDWARD ISLANDS' LIFE-SUPPORT SYSTEM: RELATIVE IMPORTANCE OF LOCAL AND ADVECTED SOURCES // Ученые записки КФУ. Естественные науки 2009 N2

За последние 30 лет было описано несколько механизмов объясняющих динамику планктона, а также обеспечение пищей островных хищников и донных сообществ в районе островов Принца Эдуарда. Предложенные механизмы включают: (а) гипотезу апвеллинга с подветренной стороны островной системы, (б) вторжение меандров образованных выше по течению на островной шельф, (в) формирование условий для цветения фитопланктона на островном шельфе, (г) гипотеза «конвейера» доставляющего планктон на шельф островов, и (д) утилизация хищниками фронтальных систем и топографически генерируемых круговоротов выше по течению или в непосредственной близости к островам. Предполагается, что «система жизнеобеспечения» островов Принца Эдуарда включает в себя все перечисленные выше компоненты. Их важность критически рассмотрена и оценена в связи с изменчивостью внешней среды вокруг островов. Базируясь на недавних исследованиях с использованием стабильных изотопов, количественно оценена важность аллохтонных (внешних) и автохтонных (локальных) источников энергии в различных экосистемах островов Принца Эдуарда. В частности, впервые для экосистемы островов показана важность органики поступающей от прибрежных бурых водорослей ламинари

Shifting baselines in Antarctic ecosystems; ecophysiological response to warming in Lissarca miliaris at Signy Island, Antarctica

The Antarctic Peninsula has experienced a rapid increase in atmospheric temperature over the last 50 years. Whether or not marine organisms thriving in this cold stenothermal environment are able to cope with warming is of concern. Here, we present changes to the growth and shell characteristics of the ecologically important, small and short lived brooding bivalve Lissarca miliaris from Signy Island, Antarctica. Using material collected from the 1970’s to the present day, we show an increase in growth rate and adult shell deterioration accompanied by a decrease in offspring size, associated with an increase in annual average temperatures. Critical changes to the bivalve’s ecology seen today evidence the problem of a shift in baseline since the onset of warming recorded in Antarctica. These small bivalves are demonstrating ecophysiological responses to subtle warming that, provided warming continues, could soon surpass a physiological tipping point, adding to warming associated threats such as increased predatory pressure and ocean acidification

Nitrogen isotopic baselines and implications for estimating foraging habitat and trophic position of yellowfin tuna in the Indian and Pacific Oceans

International audienceAssessment of isotopic compositions at the base of food webs is a prerequisite for using stable isotope analysis to assess foraging locations and trophic positions of marine organisms. Our study represents a unique application of stable-isotope analyses across multiple trophic levels (primary producer, primary consumer and tertiary consumer) and over a large spatial scale in two pelagic marine ecosystems. We found that delta N-15 values of particulate organic matter (POM), barnacles and phenylalanine from the muscle tissue of yellowfin tuna all showed similar spatial patterns. This consistency suggests that isotopic analysis of any of these can provide a reasonable proxy for isotopic variability at the base of the food web. Secondly, variations in the delta N-15 values of yellowfin tuna bulk-muscle tissues paralleled the spatial trends observed in all of these isotopic baseline proxies. Variation in isotopic composition at the base of the food web, rather than differences in tuna diet, explained the 11 parts per thousand variability observed in the bulk-tissue delta N-15 values of yellowfin tuna. Evaluating the trophic position of yellowfin tuna using amino-acid isotopic compositions across the western Indian and equatorial Pacific Oceans strongly suggests these tuna occupy similar trophic positions, albeit absolute trophic positions estimated by this method were lower than expected. This study reinforces the importance of considering isotopic baseline variability for diet studies, and provides new insights into methods that can be applied to generate nitrogen isoscapes for worldwide comparisons of top predators in marine ecosystem

Physical setup of the HiL test system for testing THR.

<p>The THR components are fixed on mounting devices attached to the endeffector and the compliant support, respectively. Measurements are taken via the force-torque sensor and displacement sensors.</p

Multibody system of the lower extremity for testing THR.

<p>(a) Multibody topology with illustration of the joint coordinates and the fictive planar joint in the sagittal plane indicated as one revolute (R) and two prismatic (P) joints. (b) Measured and transferred coordinates <math><msub><mi>c</mi><mo>¯</mo><mn>1</mn></msub></math>, <math><msub><mi>c</mi><mo>¯</mo><mn>2</mn></msub></math>, <math><msub><mi>c</mi><mo>¯</mo><mn>3</mn></msub></math> in constrained directions of the THR. (c) Musculoskeletal model with implanted CAD geometries of the THR.</p

Impact of muscle element removal emulating a posterior surgical approach on HiL-simulated THR load situation with focus on the sitting down phase of the deep maneuver.

<p>The HiL simulations are based on parameter sets ②, ③ from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0145798#pone.0145798.t001" target="_blank">Table 1</a>. <b>a</b> Comparison between the intact (blue lines) and the resected (red lines) case for hip joint rotations <i>q</i>₃, <i>q</i>₁, <i>q</i>₂, measured displacement |<i><b>c</b></i>| between femoral head and acetabular cup, components of the predicted reaction force <i><b>f</b></i>^<i>r</i> given in the pelvic reference frame [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0145798#pone.0145798.ref049" target="_blank">49</a>], and measured resisting torque |<i><b>τ</b></i>^<i>f</i>|. Impingement occurs at ○ and dislocation at ◇. <b>b</b> Direction of the hip joint reaction force with respect to the frontal plane of the pelvic reference frame [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0145798#pone.0145798.ref049" target="_blank">49</a>] with illustration of the head position at and after impingement for the intact (above) and the resected (below) case.</p

Functional principle of the HiL simulation for testing THR with respect to dislocation.

<p>The transfer between the musculoskeletal model and the physical setup is illustrated within the two control loops on kinematic and force level, respectively. The THR components are attached to mounting devices which are fixed to the endeffector of the robot (stem) and the compliant support (cup).</p