Reproductive Success of Amnicola limosa (Gastropoda) in Low Alkalinity Lakes in South-Central Ontario

1989 ◽  
Vol 46 (5) ◽  
pp. 863-869 ◽  
Author(s):  
Margo A. Shaw ◽  
Gerald L. Mackie
Keyword(s):  
Life Cycle ◽  
Reproductive Success ◽  
Hatching Success ◽  
Low Ph ◽  
Critical Stage ◽  
Percent Survival ◽  
South Central ◽  
Order Of Magnitude ◽  
Magnitude Difference

The reproductive success of the gastropod Amnicola limosa was examined in six lakes ranging in pH from 4.62 to 7.42 to determine which stages in the life cycle were most sensitive to acidification. Although fecundity was significantly greater (p < 0.01) for adults reared at pH 7.42 than at pH 5.89–6.64, a failure to oviposit was documented only at pH 4.62. Hatching success was uniformly high (88–97%) at pH 5.59 to 7.42, while embryos incubated at pH 4.62 suffered complete mortality. The most critical stage in the life cycle is the newly hatched stage. Survival during the 20 d post hatch ranged from 23% at pH 5.59 to 69% at pH 7.42. There was an order of magnitude difference in the cumulative percent survival of recruits in lakes ranging in pH from 5.59 (5.1%) to 7.42 (44.0%). Juveniles raised at low pH (5.59–5.70) were on average 0.20 mm (20%) smaller than those in circumneutral lakes (pH 6.64–7.42). The present low densities of Amnicola limosa in Heney Lake (pH 5.59) can be explained by low recruitment since 1980. Evidence presented suggests that the disappearance of this species from clear low pH lakes (pH < 5.8) is due to reductions in fecundity and hatchling survival.

Effects of Calcium and pH on the Reproductive Success of Amnicola limosa (Gastropoda)

1990 ◽  
Vol 47 (9) ◽  
pp. 1694-1699 ◽  
Author(s):  
Margo A. Shaw ◽  
Gerry L. Mackie
Keyword(s):  
Reproductive Success ◽  
Embryonic Development ◽  
Water Chemistry ◽  
Laboratory Experiments ◽  
Calcium Concentration ◽  
Hatching Success ◽  
South Central ◽  
Naturally Occurring ◽  
Ph Range ◽  
The Relationship

Field and laboratory experiments were designed to examine the relationship between water chemistry (especially pH and calcium) and the reproductive success of Amnicola limosa. Fecundity (no. eggs∙female−1) was positively correlated with lake buffering capacity (P = 0.002) in naturally occurring populations. We documented a 66% reduction in fecundity in lakes over a pH range of 7.6–5.8. However, fecundity was higher than expected in a highly-coloured, low-pH lake. The number of juveniles produced per egg was not related to any water chemistry variable (multiple R2 = 0.186). A laboratory experiment demonstrated that pH, and not calcium, was limiting embryonic development. All embryos held at pH 4.5 failed to hatch. Eggs held at pH 5.5 experienced reduced hatching success (P = 0.013) and delayed development (P < 0.001) compared with those held at pH 6.5. Length of newly hatched snails did not differ significantly between treatments (P = 0.891). The critical calcium concentration required for embryonic development in laboratory incubation lay between 0.14 and 1.11 mg∙L−1. This is well below the calcium concentration of acidifying lakes in south-central Ontario.

TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

2003 ◽  
Vol 764 ◽  
Author(s):  
D.N. Zakharov ◽  
Z. Liliental-Weber ◽  
A. Motayed ◽  
S.N. Mohammad
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Resolution Electron ◽  
Order Of Magnitude ◽  
Contact Surfaces ◽  
Electron Energy Loss ◽  
Magnitude Difference

AbstractOhmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

scholarly journals Sustainable Panels Made with Industrial and Agricultural Waste: Thermal and Environmental Critical Analysis of the Experimental Results

2021 ◽  
Vol 11 (2) ◽  
pp. 494
Author(s):  
Paola Ricciardi ◽  
Elisa Belloni ◽  
Francesca Merli ◽  
Cinzia Buratti
Keyword(s):  
Thermal Conductivity ◽  
Life Cycle ◽  
Rice Husk ◽  
Agricultural Waste ◽  
Embodied Energy ◽  
Waste Materials ◽  
Impact Reduction ◽  
Combined Solution ◽  
Order Of Magnitude ◽  
Recycled Waste

Recycled waste materials obtained from industrial and agricultural processes are becoming promising thermal and acoustic insulating solutions in building applications; their use can play an important role in the environmental impact reduction. The aim of the present paper is the evaluation of the thermal performance of recycled waste panels consisting of cork scraps, rice husk, coffee chaff, and end-life granulated tires, glued in different weight ratios and pressed. Six panels obtained from the mixing of these waste materials were fabricated and analyzed. In particular, the scope is the selection of the best compromise solutions from the thermal and environmental points of view. To this aim, thermal resistances were measured in laboratory and a Life Cycle Assessment (LCA) analysis was carried out for each panel; a cross-comparative examination was performed in order to optimize their properties and find the best panels solutions to be assembled in the future. Life Cycle Analysis was carried out in terms of primary Embodied Energy and Greenhouse Gas Emissions, considering a ‘‘cradle-to-gate” approach. The obtained thermal conductivities varied in the 0.055 to 0.135 W/mK range, in the same order of magnitude of many traditional systems. The best thermal results were obtained for the panels made of granulated cork, rice husk, and coffee chaff in this order. The rubber granulate showed higher values of the thermal conductivity (about 0.15 W/mK); a very interesting combined solution was the panel composed of cork (60%), rice husk (20%), and coffee chaff (20%), with a thermal conductivity of 0.08 W/mK and a Global Warming Potential of only 2.6 kg CO2eq/m2. Considering the Embodied Energy (CED), the best solution is a panel composed of 56% of cork and 44% of coffee chaff (minimum CED and thermal conductivity).

More sires may enhance offspring fitness in Northern Map Turtles (Graptemys geographica)

2013 ◽  
Vol 91 (8) ◽  
pp. 581-588 ◽  
Author(s):  
Nicola Banger ◽  
Gabriel Blouin-Demers ◽  
Grégory Bulté ◽  
Stephen C. Lougheed
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Hatching Success ◽  
Locomotor Performance ◽  
Conservative Estimate ◽  
Genetic Quality ◽  
Offspring Fitness ◽  
Sexual Selection Theory ◽  
Map Turtles ◽  
Graptemys Geographica

Sexual selection theory predicts that males should be promiscuous to maximize their reproductive success, while females should be choosy. Yet females of many taxa often produce progeny sired by multiple males, indicating that promiscuity can be important for the reproductive success of females. Promiscuity may enhance the fitness of females if it increases the genetic quality, or the genetic variety, and thus the viability of their offspring. We quantified the number of sires per clutch in a population of Northern Map Turtles (Graptemys geographica (LeSueur, 1817)) in Lake Opinicon, Ontario, Canada, and tested whether the number of sires affects several metrics of viability in hatchlings. Based on the most conservative estimate, at least 71% of clutches in this population are sired by multiple males, but there was no evidence that larger clutches are sired by more males. Clutches sired by more males had higher hatching success and survival, but the differences were not statistically significant. We did not find any effect of the number of sires on hatchling morphology or locomotor performance. Collectively, our results partially support the hypothesis that promiscuity can increase the reproductive success of female Northern Map Turtles.

Reproduction of selected Mollusca in some low alkalinity lakes in south-central Ontario

1985 ◽  
Vol 63 (3) ◽  
pp. 511-515 ◽  
Author(s):  
M. R. Servos ◽  
J. B. Rooke ◽  
G. L. Mackie
Keyword(s):  
Low Ph ◽  
Acidic Lakes ◽  
Recruitment Failure ◽  
South Central ◽  
Summer Growth ◽  
Growth And Reproduction

Growth and reproduction of several species of molluscs were examined in six low alkalinity lakes in south-central Ontario. Amnicola limosa (Gastropoda: Amnicolidae) held through the summer of 1982 in cages in acidic lakes (pH 5.78–5.89) grew slower (p < 0.01) than those held in less acidic lakes (pH 6.03–6.84). The development of eggs of A. limosa in the laboratory was impaired at and below pH 5.0 and delayed at pH 5.5 relative to pH 6.0. Hence the recruitment failure and elimination of A. limosa that has been reported in acidifying lakes may be caused by reduced summer growth and (or) impaired development of the eggs. In contrast, Pisidium spp. (Bivalvia: Pisidiidae) do not appear to be adversely affected by low pH in the lakes in this study (pH 5.78–6.84). Caged Pisidium equilaterale did not have reduced growth in the acidic lakes during the summer of 1982. Pisidium casertanum and Pisidium ferrugineum had only slightly reduced (p < 0.05) fecundity (number of extramarsupial larvae per adult) in acidic lakes relative to less acidic lakes sampled in 1980.

Clutch quality is related to embryonic development duration, hatchling body size and telomere length in the spined toad (Bufo spinosus)

2021 ◽  
Vol 133 (1) ◽  
pp. 135-142
Author(s):  
Marion Cheron ◽  
Frédéric Angelier ◽  
Cécile Ribout ◽  
François Brischoux
Keyword(s):  
Reproductive Success ◽  
Embryonic Development ◽  
Parental Care ◽  
Telomere Length ◽  
Mate Selection ◽  
Hatching Success ◽  
Egg Quality ◽  
Parental Quality ◽  
Complex Interactions ◽  
Development Duration

Abstract Reproductive success is often related to parental quality, a parameter expressed through various traits, such as site selection, mate selection and energetic investment in the eggs or progeny. Owing to the complex interactions between environmental and parental characteristics occurring at various stages of the reproductive event, it is often complicated to tease apart the relative contributions of these different factors to reproductive success. Study systems where these complex interactions are simplified (e.g. absence of parental care) can help us to understand how metrics of parental quality (e.g. gamete and egg quality) influence reproductive success. Using such a study system in a common garden experiment, we investigated the relationships between clutch hatching success (a proxy of clutch quality) and offspring quality in an amphibian species lacking post-oviposition parental care. We found a relationship between clutch quality and embryonic development duration and hatchling phenotype. We found that hatchling telomere length was linked to hatching success. These results suggest that clutch quality is linked to early life traits in larval amphibians and that deciphering the influence of parental traits on the patterns we detected is a promising avenue of research.

scholarly journals Submesoscale Cold Filaments in the Gulf Stream

2014 ◽  
Vol 44 (10) ◽  
pp. 2617-2643 ◽  
Author(s):  
Jonathan Gula ◽  
M. Jeroen Molemaker ◽  
James C. McWilliams
Keyword(s):  
Life Cycle ◽  
Gulf Stream ◽  
Baroclinic Instability ◽  
Vertical Mixing ◽  
Thermal Wind ◽  
Filament Dynamics ◽  
Oceanic Surface ◽  
Secondary Circulations ◽  
Order Of Magnitude ◽  
Surface Buoyancy

Abstract A set of realistic, very high-resolution simulations is made for the Gulf Stream region using the oceanic model Regional Oceanic Modeling System (ROMS) to study the life cycle of the intense submesoscale cold filaments that form on the subtropical gyre, interior wall of the Gulf Stream. The surface buoyancy gradients and ageostrophic secondary circulations intensify in response to the mesoscale strain field as predicted by the theory of filamentogenesis. It can be understood in terms of a dual frontogenetic process, along the lines understood for a single front. There is, however, a stronger secondary circulation due to the amplification at the center of a cold filament. Filament dynamics in the presence of a mixed layer are not adequately described by the classical thermal wind balance. The effect of vertical mixing of momentum due to turbulence in the surface layer is of the same order of magnitude as the pressure gradient and Coriolis force and contributes equally to a so-called turbulent thermal wind balance. Filamentogenesis is disrupted by vigorous submesoscale instabilities. The cause of the instability is the lateral shear as energy production by the horizontal Reynolds stress is the primary fluctuation source during the process; this contrasts with the usual baroclinic instability of submesoscale surface fronts. The filaments are lines of strong oceanic surface convergence as illustrated by the release of Lagrangian parcels in the Gulf Stream. Diabatic mixing is strong as parcels move across the filaments and downwell into the pycnocline. The life cycle of a filament is typically a few days in duration, from intensification to quasi stationarity to instability to dissipation.

Laboratory comparison of the relative success of Biomphalaria glabrata stocks which are susceptible and insusceptible to infection with Schistosoma mansoni

Parasitology ◽  
1983 ◽  
Vol 86 (2) ◽  
pp. 335-344 ◽  
Author(s):  
D. J. Minchella ◽  
P. T. Loverde
Keyword(s):  
Life Cycle ◽  
Natural Selection ◽  
Reproductive Success ◽  
Natural Populations ◽  
Biomphalaria Glabrata ◽  
Selective Advantage ◽  
Controlled Conditions ◽  
Plausible Answer ◽  
Major Objection ◽  
Transmit Disease

SUMMARYA method of interrupting the life-cycle of the human blood fluke Schistosoma by increasing the proportion of genetically insusceptible intermediate host snails in natural populations was first proposed nearly 25 years ago. The method assumes that insusceptible snails will be at a selective advantage over susceptible snails when the schistosome parasite is present, and therefore natural selection will act to increase the proportion of alleles for insusceptibility. A major objection to the proposed technique is ‘If insusceptible snails are at a selective advantage, then why are they not predominant in natural populations that transmit disease?’ One explanation of this paradox is that insusceptibility may be associated with a disadvantageous character or a physiological defect. This study tests this hypothesis by measuring the relative reproductive success of susceptible and insusceptible snails under controlled conditions. Results indicate that insusceptible (unsuitable) snails are negatively affected in the presence of either susceptible snails or schistosome parasites. Furthermore, in the presence of both susceptible snails and schistosome parasites, insusceptible snails are selectively disadvantaged compared to susceptible snails. These results obtained under laboratory-controlled conditions suggest a plausible answer as to why insusceptible snails are not predominant in natural populations that transmit disease.

Evaluating the temperature dependence of bedrock hillslope erosion in the Mont Blanc massif using in situ cosmogenic 3He-10Be-14C

2021 ◽  
Author(s):  
Donovan P. Dennis ◽  
Dirk Scherler ◽  
Samuel Niedermann ◽  
Kristina Hippe ◽  
Hella Wittmann ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Erosion Rates ◽  
Close Proximity ◽  
Order Of Magnitude ◽  
Stochastic Events ◽  
Exposure Ages ◽  
Alpine Environments ◽  
Magnitude Difference ◽  
Mont Blanc Massif

&lt;p&gt;The erosion of cold bedrock hillslopes in alpine environments depends not only on rates of frost weathering and accumulated rock damage, but additionally on the removal of the weathered material from the bedrock surface. In the Mont Blanc massif, steep bedrock faces with exposure ages sometimes much older than 50,000 years sit in close proximity to actively-eroding rockwalls, suggesting a more complex relationship between temperature and erosion rates than encompassed by the proposed &amp;#8220;frost-cracking window.&amp;#8221; Stochastic events like rockfalls and rock avalanches, despite their rarity, contribute a non-trivial proportion of the total sediment budget in alpine permafrost regions, adding to the contribution from background &amp;#8220;steady-state&amp;#8221; erosion. Employing a methodology based on the combination of in-situ cosmogenic nuclides &lt;sup&gt;3&lt;/sup&gt;He -&lt;sup&gt;10&lt;/sup&gt;Be-&lt;sup&gt;14&lt;/sup&gt;C, we test the temperature-dependence of high-alpine erosion while taking into account erosional stochasticity.&lt;/p&gt;&lt;p&gt;From cosmogenic &lt;sup&gt;10&lt;/sup&gt;Be concentrations of amalgamated samples collected on the Aiguille du Midi (3842 m a.s.l.) in the Mont Blanc massif, we find an order of magnitude difference in erosion rate across the peak&amp;#8217;s surface. Our preliminary measured erosion rates, ranging between appx. 0.03 mm yr&lt;sup&gt;-1&lt;/sup&gt; and 1.0 mm yr&lt;sup&gt;-1&lt;/sup&gt;, correlate neither with modern temperature measurements from borehole thermistors, nor with our current estimates of bedrock cosmogenic &lt;sup&gt;3&lt;/sup&gt;He-derived paleotemperatures. The corresponding cosmogenic &lt;sup&gt;14&lt;/sup&gt;C/&lt;sup&gt;10&lt;/sup&gt;Be ratios (between 1.70 and 4.0) for these erosion rates indicate that our measurements are not biased by recent stochastic rockfall events. Our current results therefore suggest that on geomorphic timescales, bedrock hillslope erosion rates are not set solely by rates of frost-cracking, but rather by the combined effects of frost-cracking and permafrost thaw-induced rockfalls. These insights are relevant both for short-term monitoring of alpine permafrost and associated geohazards under a warming climate, as well as studies of proposed &amp;#8220;buzzsaws&amp;#8221; operating on glacial-interglacial timescales.&lt;/p&gt;

scholarly journals Amblyomma rotundatum (Koch, 1844) (Acari: Ixodidae) two-host life-cycle on Viperidae snakes

2010 ◽  
Vol 19 (3) ◽  
pp. 174-178 ◽  
Author(s):  
Daniel Sobreira Rodrigues ◽  
Ricardo Maciel ◽  
Lucas Maciel Cunha ◽  
Romário Cerqueira Leite ◽  
Paulo Roberto de Oliveira
Keyword(s):  
Life Cycle ◽  
North America ◽  
Relative Humidity ◽  
Total Duration ◽  
Ixodid Tick ◽  
Natural Conditions ◽  
South Central ◽  
Controlled Conditions ◽  
In Captivity ◽  
Host Life

Amblyomma rotundatum is an ixodid tick that infests ectothermic animals and reproduces exclusively by parthenogenesis. This tick has been frequently reported to infest reptiles and amphibians, under natural conditions and sometimes in captivity. It was described in Brazil and several other countries of South, Central and North America. Although many studies have reported aspects of its biology, none of them has used regularly either ophidian as hosts, or controlled temperature, humidity and luminosity for parasitic stages. The objective of this experiment was to study the life cycle of A. rotundatum feeding on Viperidae snakes under room controlled conditions at 27 ± 1 ºC temperature, 85 ± 10% relative humidity and 12:12 hours photoperiod for parasitic stages, and under B.O.D incubator conditions at 27 ± 1 ºC temperature, 85 ± 10% relative humidity and scotophase for non-parasitic stages. The total duration of the life cycle ranged from 56 to 163 days (mean of 105 days). Two-host life cycle was observed for most of the ixodid population studied.

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