The effects of transportation stress and barnacle fouling on predation rates of starfish (Asterias rubens) on mussels (Mytilus edulis).

The starfish, Asterias rubens, is widely distributed throughout the northern hemisphere and is an important predator on benthic mussel (Mytilus edulis) beds. Whilst several studies have examined how the size of individuals determines this predator–prey relationship, less is known about how the physiological condition of the prey (mussels) and the extent of their fouling may alter these relationships. Such issues are of particular interest to those working within the benthic mussel cultivation industry to inform best management practice and to help minimise losses during the aquaculture process. The potential role of starfish in the removal of epibiotic barnacles from mussels, the presence of which increases processing costs within the industry, is also of interest. We tested whether stressing mussels by aerial exposure for 48 h and whether the extent of barnacle fouling on mussels affected the feeding rates of three different size classes of starfish feeding on two different size classes of mussels. Feeding rates on stressed and unstressed mussels were similar for each starfish–mussel size combination. Barnacle fouling reduced the feeding rate of medium-sized starfish on larger-sized mussels. We also observed starfish, of all size classes, preying directly on the epibiotic barnacles on mussels, however, feeding rates were low and considered unlikely to reduce the extent of fouling on mussels. Our findings show that the predator–prey relationship between starfish and mussels does not differ between unstressed mussels and those experimentally stressed by aerial exposure for 48 h so that this level of stress is unlikely to affect predation rates by A. rubens following relaying in commercial operations. Whilst barnacle fouling suppressed predation rates in one of our experimental treatments, it does not appear that fouling by barnacles would provide a significant refuge from predation for the majority of mussels in benthic aquaculture stocks. Instead we found the size relationship between starfish and mussels was more important in determining predation rates. Starfish are also unlikely to help reduce barnacle fouling on cultured mussels by preying solely on fouling barnacles and the need to control starfish predation during culture remains.

Rates of E1, E2, M1, and M2 transitions in Ni II

Aims. We present rates for all E1, E2, M1, and M2 transitions among the 295 fine-structure levels of the configurations 3d⁹, 3d⁸4s, 3d⁷4s², 3d⁸4p, and 3d⁷4s4p, determined through an extensive configuration interaction calculation. 

Methods. The CIV3 code developed by Hibbert and coworkers is used to determine for these levels configuration interaction wave functions with relativistic effects introduced through the Breit-Pauli approximation. 

Results. Two different sets of calculations have been undertaken with different 3d and 4d functions to ascertain the effect of such variation. The main body of the text includes a representative selection of data, chosen so that key points can be discussed. Some analysis to assess the accuracy of the present data has been undertaken, including comparison with earlier calculations and the more limited range of experimental determinations. The full set of transition data is given in the supplementary material as it is very extensive. 

Conclusions. We believe that the present transition data are the best currently available.

Analysis of annuli in otoliths, age distribution and growth rates of the Namibian hake (Merluccius capensis)

Dissertação mest., Gestão da Água e da Costa, Universidade do Algarve, 2007

Effects of environmental conditions on planktonic abundances, benthic recruitment and growth rates of the bivalve mollusc Ruditapes decussatus in a Portuguese coastal lagoon

Controlling environmental parameters for the early stages of marine invertebrates have received little attention, particularly in field studies. This study involves measurement of abundances and growth rates of the bivalve Ruditapes decussatus Linnaeus 1758 during its planktonic larval and early benthic life stages in a coastal lagoon: Ria Formosa, Portugal. Measured abundances were compared with tidal amplitude, water temperature, salinity, wind velocity and direction, and a food availability indicator 2chlorophyll a). Data were obtained on abundance and prodissoconch length of the larvae, measured two tothreetimes perweek,and ofpost-larval stagesindividuals thathadsettled inartificial collectors over10months.Larval and juvenile cohorts were identified using size-frequency distributions and larval ages estimated by larval shell growth lines.

Trophic Level Asynchrony in Rates of Phenological Change For Marine, Freshwater and Terrestrial Environments

Recent changes in the seasonal timing (phenology) of familiar biological events have been one of the most conspicuous signs of climate change. However, the lack of a standardised approach to analysing change has hampered assessment of consistency in such changes among different taxa and trophic levels and across freshwater, terrestrial and marine environments. We present a standardised assessment of 25 532 rates of phenological change for 726 UK terrestrial, freshwater and marine taxa. The majority of spring and summer events have advanced, and more rapidly than previously documented. Such consistency is indicative of shared large-scale drivers. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. Less coherent patterns in some groups of organisms point to the agency of more local scale processes and multiple drivers. For the first time we show a broad scale signal of differential phenological change among trophic levels; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services

Comparing growth rates of natural phytoplankton communities to laboratory culturing experiments

Senior thesis written for Oceanography 445

Safety and occlusion rates of surgical treatment of unruptured intracranial aneurysms: a systematic review and meta-analysis of the literature from 1990 to 2011.

BACKGROUND AND PURPOSE: Surgical clipping of unruptured intracranial aneurysms (UIAs) has recently been challenged by the emergence of endovascular treatment. We performed an updated systematic review and meta-analysis on the surgical treatment of UIAs, in an attempt to determine the aneurysm occlusion rates and safety of surgery in the modern era. METHODS: A detailed protocol was developed prior to conducting the review according to the Cochrane Collaboration guidelines. Electronic databases spanning January 1990-April 2011 were searched, complemented by hand searching. Heterogeneity was assessed using I(2), and publication bias with funnel plots. Surgical mortality and morbidity were analysed with weighted random effect models. RESULTS: 60 studies with 9845 patients harbouring 10 845 aneurysms were included. Mortality occurred in 157 patients (1.7%; 99% CI 0.9% to 3.0%; I(2)=82%). Unfavourable outcomes, including death, occurred in 692 patients (6.7%; 99% CI 4.9% to 9.0%; I(2)=85%). Morbidity rates were significantly greater in higher quality studies, and with large or posterior circulation aneurysms. Reported morbidity rates decreased over time. Studies were generally of poor quality; funnel plots showed heterogeneous results and publication bias, and data on aneurysm occlusion rates were scant. CONCLUSIONS: In studies published between 1990 and 2011, clipping of UIAs was associated with 1.7% mortality and 6.7% overall morbidity. The reputed durability of clipping has not been rigorously documented. Due to the quality of the included studies, the available literature cannot properly guide clinical decisions.

Convergence Rates of Approximation by Translates

In this paper we consider the problem of approximating a function belonging to some funtion space Φ by a linear comination of n translates of a given function G. Ussing a lemma by Jones (1990) and Barron (1991) we show that it is possible to define function spaces and functions G for which the rate of convergence to zero of the erro is 0(1/n) in any number of dimensions. The apparent avoidance of the "curse of dimensionality" is due to the fact that these function spaces are more and more constrained as the dimension increases. Examples include spaces of the Sobolev tpe, in which the number of weak derivatives is required to be larger than the number of dimensions. We give results both for approximation in the L2 norm and in the Lc norm. The interesting feature of these results is that, thanks to the constructive nature of Jones" and Barron"s lemma, an iterative procedure is defined that can achieve this rate.

Can Italy and Spain survive rates of 6-7%? CEPS Policy Brief No. 279, 27 July 2012

The sentiment that the euro is now in real danger is based in large part on the widespread conviction that interest rates of 6-7% are simply unsustainable for both Italy and Spain., After taking a closer look at the fundamentals, however, Daniel Gros concludes in this new Policy Brief that both countries should be able to live with this level of interest rates for quite some time, but only if they mobilize domestic savings, which remain strong in both countries. For Spain, some debt/equity swaps are also needed.

Searching for the perfect surface area normalizing term - a comparison of BET surface area-, geometric surface area- and mass-normalized dissolution rates of anorthite and biotite

Dissolution rates were calculated for a range of grain sizes of anorthite and biotite dissolved under far from equilibrium conditions at pH 3, T = 20 degrees C. Dissolution rates were normalized to initial and final BET surface area, geometric surface area, mass and (for biotite only) geometric edge surface area. Constant (within error) dissolution rates were only obtained by normalizing to initial BET surface area for biotite. The normalizing term that gave the smallest variation about the mean for anorthite was initial BET surface area. In field studies, only current (final) surface area is measurable. In this study, final geometric surface area gave the smallest variation for anorthite dissolution rates and final geometric edge surface area for biotite dissolution rates. (c) 2005 Published by Elsevier B.V.

Comparison of survival rates of captive-reared and wild-bred Mauritius kestrels (Falco punctatus) in a re-introduced population

Re-introduction is a technique widely used in the conservation of threatened bird species. With advances in aviculture the use of captive-produced individuals as the release stock is becoming more commonplace, and ideally, survival of captive-produced, released individuals should be no different from their wild-bred counterparts. During the late 1980s the Critically Endangered Mauritius kestrel (Falco punctatus) was successfully re-introduced into the Bambous mountain range, Mauritius, some 30 years after its local extinction. Between 1987 and 2001 the developing population was closely monitored enabling us to construct re-sighting histories for 88 released and 284 wild-bred kestrels. We used age-structured models in the survival analysis software program MARK to determine if an individual's origin influenced its subsequent survival. Our analysis indicated no compelling evidence for reduced survival among juvenile captive-reared and released individuals, relative to their wild-bred counterparts, across the majority of cohorts and only limited evidence of a cohort-specific effect. This study illustrates that despite the lack of a formal experimental approach it is still feasible to conduct an assessment of re-introduction outcomes and techniques.

Rates of production of acetate, propionate, and butyrate in the rumen of lactating dairy cows given normal and low-roughage diets

Five lactating dairy cows with a permanent cannula in the rumen were given ( kg DM/d) a normal diet (7.8 concentrates, 5.1 hay) or a low-roughage (LR) diet (11.5 concentrates, 1.2 hay) in two meals daily in a two-period crossover design. Milk fat (g/kg) was severely reduced on diet LR. To measure rates of production of individual volatile fatty acids (VFA) in the rumen, 0.5 mCi 1-C-14-acetic acid, 2-C-14-propionic acid, or 1-C-14-n-butyric acid were infused into the rumen for 22 h at intervals of 2 to 6 d; rumen samples were taken over the last 12 h. To measure rumen volume, we infused Cr-EDTA into the rumen continuously, and polyethylene glycol was injected 2 h before the morning feed. Results were very variable, so volumes measured by rumen emptying were used instead. Net production of propionic acid more than doubled on LR, but acetate and butyrate production was only numerically lower. Net production rates pooled across both diets were significantly related to concentrations for each VFA. Molar proportions of net production were only slightly higher than molar proportions of concentrations for acetate and propionate but were lower for butyrate. The net energy value (MJ/d) of production of the three VFA increased from 89.5 on normal to 109.1 on LR, equivalent to 55 and 64% of digestible energy, respectively. Fully interchanging, three-pool models of VFA C fluxes are presented. It is concluded that net production rates of VFA can be measured in non-steady states without the need to measure rumen volumes.

Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

1. Estimates of seed bank depletion rates are essential for modelling and management of plant populations. The seed bag burial method is often used to measure seed mortality in the soil. However, the density of seeds within seed bags is higher than densities in natural seed banks, which may elevate levels of pathogens and influence seed mortality. The aim of this study was to quantify the effects of fungi and seed density within buried mesh bags on the mortality of seeds. Striga hermonthica was chosen as the study species because it has been widely studied but different methods for measuring seed mortality in the soil have yielded contradictory estimates. 2. Seed bags were buried in soil and exhumed at regular time intervals to monitor mortality of the seeds in three field experiments during two rainy seasons. The effect of fungal activity on seed mortality was evaluated in a fungi exclusion experiment. Differences in seed-to-seed interaction were obtained by using two and four densities within the seed bags in consecutive years. Densities were created by mixing 1000 seeds with 0, 10, 100 or 1000 g of coarse sand. 3. The mortality rate was significantly lower when fungi were excluded, indicating the possible role of pathogenic fungi. 4. Decreasing the density of seeds in bags significantly reduced seed mortality, most probably because of decreased seed-to-seed contamination by pathogenic fungi. 5. Synthesis and applications. Models of plant populations in general and annual weeds in particular often use values from the literature for seed bank depletion rates. These depletion rates have often been estimated by the seed bag burial method, yet seed density within seed bags may be unrealistically high. Consequently, estimates of seed mortality rates may be too high because of an overestimation of the effects of soil or seed-borne pathogens. Species that have been classified from such studies as having short-lived seed banks may need to be re-assessed using realistic densities either within seed bags or otherwise. Similarly, models of seed bank dynamics based on such overestimated depletion rates may lead to incorrect conclusions regarding the seed banks and, perhaps, the management of weeds and rare species.

Frequency of word-use predicts rates of lexical evolution throughout Indo-European history

Greek speakers say "ovpa", Germans "schwanz'' and the French "queue'' to describe what English speakers call a 'tail', but all of these languages use a related form of 'two' to describe the number after one. Among more than 100 Indo-European languages and dialects, the words for some meanings (such as 'tail') evolve rapidly, being expressed across languages by dozens of unrelated words, while others evolve much more slowly-such as the number 'two', for which all Indo-European language speakers use the same related word-form(1). No general linguistic mechanism has been advanced to explain this striking variation in rates of lexical replacement among meanings. Here we use four large and divergent language corpora (English(2), Spanish(3), Russian(4) and Greek(5)) and a comparative database of 200 fundamental vocabulary meanings in 87 Indo-European languages(6) to show that the frequency with which these words are used in modern language predicts their rate of replacement over thousands of years of Indo-European language evolution. Across all 200 meanings, frequently used words evolve at slower rates and infrequently used words evolve more rapidly. This relationship holds separately and identically across parts of speech for each of the four language corpora, and accounts for approximately 50% of the variation in historical rates of lexical replacement. We propose that the frequency with which specific words are used in everyday language exerts a general and law-like influence on their rates of evolution. Our findings are consistent with social models of word change that emphasize the role of selection, and suggest that owing to the ways that humans use language, some words will evolve slowly and others rapidly across all languages.