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Habitat Temperatures (habitat + temperature)
Selected AbstractsAge, growth, mortality and population structure of the oyster, Crassostrea madrasensis, in the Moheskhali Channel (southeastern coast of Bangladesh)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2008S. M. Nurul Amin Summary The population structure, age, growth, mortality and harvest intensity of the oyster Crassostrea madrasensis were examined in the Moheskhali Channel, Bangladesh between June 2003 and May 2004. The channel is a representative habitat for the area. C. madrasensis monthly length frequency data were analyzed using FiSAT software for estimating population parameters, including asymptotic length (L), growth co-efficient (K) and recruitment pattern to assess the status of the stock. Asymptotic length (L,) and growth co-efficient (K) were 20.88 cm and 0.35 year,1, respectively. The growth performance index (,,) was calculated with 2.18. The growth pattern showed negative allometric growth (b < 3), with an asymptotic weight (W) of about 1124.6 g. The oyster attained an average length of 6.17 cm at the end of 1 year. Total mortality (Z) by length-converted catch curve was estimated at 1.78 year,1, fishing mortality (F) at 0.77 year,1, and natural mortality (M) at 1.01 year,1. The exploitation level (E) of C. madrasensis was 0.43, while the maximum allowable limit of exploitation (Emax) was 0.45 for the highest yield. The recruitment pattern was continuous, displaying a single major peak event per year. Habitat temperatures were 25.5,31.0°C (mean ± SD, 29 ± 1.62°C); salinity range was from 12.36 to 26.0 ppt (mean ± SD, 19.6 ± 4.7 ppt). The exploitation level (0.43) indicated that the oyster stock was exploited at almost maximum yield in this channel. [source] Voltinism flexibility of a riverine dragonfly along thermal gradientsGLOBAL CHANGE BIOLOGY, Issue 3 2008ERIK BRAUNE Abstract Potential effects of future warming should be reflected in life history patterns of aquatic organisms observed in warmer climates or in habitats that are different in ambient temperature. In the special case of the dragonfly Gomphus vulgatissimus (L.) (Odonata: Gomphidae) previous research suggests that voltinism decreases from south to north. We analysed data on voltinism from 11 sample sites along a latitudinal gradient from about 44°N to 53°N, comprising small streams to medium-sized rivers. Furthermore, to simulate different conditions and to allow projections for future climate change scenarios, we developed a population dynamic model based on a projection matrix approach. The parameters of the model are dependent on temperature and day length. Our field results indicate a decrease in voltinism along the latitudinal gradient from southern to northern Europe and a corresponding increase of voltinism with higher temperatures. An increase in voltinism with width of the running water implies an effect of varying habitat temperature. Under the impact of global warming, our model predicts an increased development speed, particularly in the northern part of the latitudinal gradient, an extension of the northern range limit and changes in phenology of G. vulgatissimus, leading to an extension of the flight season in certain regions along the gradient. [source] Experimental manipulation reveals the importance of refuge habitat temperature selected by lizardsAUSTRAL ECOLOGY, Issue 3 2010MICHA ANDERSSON Abstract Refuges provide shelter from predators, and protection from exposure to the elements, as well as other fitness benefits to animals that use them. In ectotherms, thermal benefits may be a critical aspect of refuges. We investigated microhabitat characteristics of refuges selected by a heliothermic scincid lizard, Carlia rubrigularis, which uses rainforest edges as habitat. We approached lizards in the field, simulating a predator attack, and quantified the refuge type used, and effect of environmental temperatures (air temperature, substrate temperature and refuge substrate temperature) on the amount of time skinks remained in refuges after hiding (emergence time). In respone to our approach, lizards were most likely to flee into leaf litter, rather than into rocks or woody debris, and emergence time was dependent on refuge substrate temperature, and on refuge substrate temperature relative to substrate temperature outside the refuge. Lizards remained for longer periods in warmer refuges, and in refuges that were similar in temperature to outside. We examined lizard refuge choice in response to temperature and substrate type in large, semi-natural outdoor enclosures. We experimentally manipulated refuge habitat temperature available to lizards, and offered them equal areas of leaf litter, woody debris and rocks. When refuge habitat temperature was unmanipulated, lizards (85%) preferred leaf litter, as they did in the field. However, when we experimentally manipulated the temperature of the leaf litter by shading, most skinks (75%) changed their preferred refuge habitat from leaf litter to woody debris or rocks. These results suggest that temperature is a critical determinant of refuge habitat choice for these diurnal ectotherms, both when fleeing from predators and when selecting daytime retreats. [source] Pushing the edge: extended activity as an alternative to risky body temperatures in a herbivorous teiid lizard (Cnemidophorus murinus: Squamata)FUNCTIONAL ECOLOGY, Issue 1 2005L. J. VITT Summary 1A combination field and laboratory study tested the hypothesis that a herbivorous lizard, Cnemidophorus murinus, extends activity at high body temperatures to digest plant material. 2Body temperatures (Tb) of active lizards averaged 37·2 °C and were no higher than those of insect-eating Cnemidophorus. 3Near constant Tb was maintained by behavioural means even though habitat temperatures varied greatly. 4Field-based behavioural data show that C. murinus extend activity by shifting among microhabitats to increase duration of time available at high Tb for digestion. 5Laboratory studies revealed large variation in selected temperatures (Tsel), but the overall average was 35·9 °C, which is lower than field Tb. 6By carefully selecting microhabitats and extending activity, C. murinus maintains constant high body temperatures to digest plant material without risking potentially lethal overheating. [source] Variation in Heat-shock Proteins and Photosynthetic Thermotolerance among Natural Populations of Chenopodium album L. from Contrasting Thermal Environments: Implications for Plant Responses to Global WarmingJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 11 2008Deepak Barua Abstract Production of heat-shock proteins (Hsps) is a key adaptation to acute heat stress and will be important in determining plant responses to climate change. Further, intraspecifc variation in Hsps, which will influence species-level response to global warming, has rarely been examined in naturally occurring plants. To understand intraspecific variation in plant Hsps and its relevance to global warming, we examined Hsp content and thermotolerance in five naturally occurring populations of Chenopodium album L. from contrasting thermal environments grown at low and high temperatures. As expected, Hsp accumulation varied between populations, but this was related more to habitat variability than to mean temperature. Unexpectedly, Hsp accumulation decreased with increasing variability of habitat temperatures. Hsp accumulation also decreased with increased experimental growth temperatures. Physiological thermotolerance was partitioned into basal and induced components. As with Hsps, induced thermotolerance decreased with increasing temperature variability. Thus, populations native to the more stressful habitats, or grown at higher temperatures, had lower Hsp levels and induced thermotolerance, suggesting a greater reliance on basal mechanisms for thermotolerance. These results suggest that future global climate change will differentially impact ecotypes within species, possibly by selecting for increased basal versus inducible thermotolerance. [source] Lessons in stability from thermophilic proteinsPROTEIN SCIENCE, Issue 7 2006Abbas Razvi Abstract Studies that compare proteins from thermophilic and mesophilic organisms can provide insights into ability of thermophiles to function at their high habitat temperatures and may provide clues that enable us to better define the forces that stabilize all proteins. Most of the comparative studies have focused on thermal stability and show, as expected, that thermophilic proteins have higher Tm values than their mesophilic counterparts. Although these comparisons are useful, more detailed thermodynamic analyses are required to reach a more complete understanding of the mechanisms thermophilic protein employ to remain folded over a wider range of temperatures. This complete thermodynamic description allows one to generate a stability curve for a protein that defines how the conformational stability (,G) varies with temperature. Here we compare stability curves for many pairs of homologous proteins from thermophilic and mesophilc organisms. Of the basic methods that can be employed to achieve enhanced thermostability, we find that most thermophilic proteins use the simple method that raises the ,G at all temperatures as the principal way to increase their Tm. We discuss and compare this thermodynamic method with the possible alternatives. In addition we propose ways that structural alterations and changes to the amino acid sequences might give rise to varied methods used to obtain thermostability. [source] Latitudinal variation in axial patterning of the medaka (Actinopterygii: Adrianichthyidae): Jordan's rule is substantiated by genetic variation in abdominal vertebral numberBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009KAZUNORI YAMAHIRA Because the body axes of fish consist of two anatomically distinct vertebrae, abdominal and caudal, one type may be more variable in number than the other and thus contribute more to morphological diversification. Jordan's rule, a geographical tendency for fish from higher latitudes to have more vertebrae, has not been examined in terms of numbers of abdominal and/or caudal vertebrae, despite its prevalence. Vertebral observations of wild populations of the medaka (Oryzias latipes) revealed that the latitudinal increase in vertebral number is caused by an increase in abdominal vertebrae; caudal vertebrae did not vary systematically across latitudes. Laboratory experiments revealed that this latitudinal cline in abdominal vertebral number persists in a range of common environments, demonstrating a genetic basis. Phenotypic plasticity was also evident: lower developmental temperatures resulted in more abdominal vertebrae. This indicates that greater numbers of abdominal vertebrae in higher latitude individuals in the wild may be caused not only by genetic factors but by lower habitat temperatures, although the contribution of the former to Jordan's rule is assessed to be much greater. The genetic basis of the latitudinal variation in abdominal vertebral number suggests that selection on functions associated with abdominal regions is the probable explanation for Jordan's rule in this fish. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 856,866. [source] | ||||||||||