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301.
302.
Sardine (Sardina pilchardus) spawning seasonality in European waters of the northeast Atlantic 总被引:3,自引:0,他引:3
Yorgos Stratoudakis Stephen Coombs Ana Lago de Lanzós Nicholas Halliday Gersom Costas Bruno Caneco Concha Franco David Conway M. Begoña Santos Alexandra Silva Miguel Bernal 《Marine Biology》2007,152(1):201-212
Egg data from ichthyoplankton monitoring sites in the western English Channel (1988–2003) and northern Spain (1990–2000) and
macroscopic maturity data from biological samples of purse seine landings in western and southern Iberia (1980–2004) are used
to describe the spawning seasonality of sardine (Sardina pilchardus) in European waters of the northeast Atlantic using generalised additive models. The fitted models reveal a double peak in
spawning activity during early summer and autumn in the western Channel, a wider spring peak off northern Spain and a broad
winter season in the western and southern Iberian Peninsula. At all sites, a high probability of spawning activity was observed
over at least 3 months of the year, with the duration of the season increasing with both decreasing latitude and increasing
fish size. Off western and southern Iberia there are indications that the spawning season has been of longer duration in recent
years for all size classes (reaching in some cases 8 months of the year for large fish). These patterns are in general agreement
with existing literature and theoretical expectations of sardine spawning being driven locally by the seasonal cycle of water
temperature, assuming preferences for spawning at 14 –15°C and avoidance for temperatures below 12°C and above 16°C. Regional
quotient plots indicated that spawning tolerance to higher temperatures increases progressively with decreasing latitude.
Despite the weak evidence for geographical differences in temperature tolerance that may have some genetic origin, the degree
of spatio-temporal overlap in sardine-spawning activity within Atlantic European waters is unlikely to promote any reproductive
isolation in that area. 相似文献
303.
This paper describes a study of the treatment of surfactant synthetic solutions by chemical and photolytic oxidation. Synthetic solutions of linear alkylbenzene sulfonates (LAS) are treated in this work as this is a model compound commonly used in the formulation of detergents, with a great presence in urban and industrial waste-waters. The application of ultraviolet (UV) radiation combined with hydrogen peroxide to oxidize linear alkylbenzene sulfonates (LAS) is shown to be suitable as a primary oxidation step since conversions of about 50% of the original compounds are achieved in the most favorable cases. Initially, the influence of the operating variables on the degradation levels is analyzed in this work. A kinetic model that considers the contributions of both direct photolysis and radical attack is also worked out. Direct photolysis is performed to determine the quantum yield in the single photodecomposition reaction. In addition, the rate constant of the reaction between hydroxyl radicals and linear alkylbenzene sulfonates in the oxidizing system H2O2/UV is determined for different operational conditions. Finally, the contribution of each oxidation pathway is quantified, resulting in a higher contribution of the radical reaction than of photolysis in all cases. 相似文献
304.
Summary. Phytotoxic activity of single and combined application of water soluble and volatile compounds of Cistus ladanifer on germination and early root growth of subterranean clover was investigated. Total germination, lag and speed of germination
were both inhibited and stimulated, with the activity of volatiles on total germination depending upon the presence of water
solubles. Antagonism between water solubles and volatiles was always found, resulting in a reduction of inhibition or a shift
from inhibition to stimulation. It is suggested that the simultaneous presence of water solubles and volatiles might result
in changes of the chemical nature of metabolites released by C. ladanifer. Early root growth was always inhibited but only by water solubles, and no interaction was found. The ecological implications
of these results are discussed in terms of the exhaustion of competitors seedbanks by a two-step process in which germination
is less inhibited or even stimulated by water solubles and volatiles, followed by a stronger and volatiles-independent inhibition
of early root growth.
Received 13 June 2001; accepted 13 Dezember 2001. 相似文献
305.
The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae
which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing
this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe
ecological imbalance, resulting in crises of anoxia and fish death.
A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation
system.
The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities
as a first step in the constitution of a database for further comparison. 相似文献
306.
The fluoride content in the water supply of the Soria province is not normally above 0.2mg L–1 and its geographical distribution is related to the lithological and geological features of the zone, the highest concentration being associated with the Miocene clay formation of the Almazán Basin.A statistical analysis confirms a connection between this fluoride content and tooth decay among children in rural areas. However, other factors such as oral hygiene and diet have been found to affect tooth decay. 相似文献
307.
Natural History: Hobby or Science? 总被引:1,自引:0,他引:1
Jesús Antonio Rivas 《Conservation biology》1997,11(3):811-812
308.
Sondes Melliti Ben Garali Inès Sahraoui Pablo de la Iglesia Mohamed Chalghaf Jorge Diogène Jamel Ksouri 《Chemistry and Ecology》2020,36(1):66-82
ABSTRACTThe seasonal variations in Pseudo-nitzschia species and domoic acid (DA) concentration were investigated, at three shellfish farms in SW coastal Mediterranean. In parallel, the toxicity of mussels was tested. Two distinct groups of species were enumerated according to morphology and size (Pseudo-nizschia delicatissima and P. seriata groups). DA was detected over a nine-week period from July to October 2012 in the Lagoon, with a maximum concentration recorded in July (12.71?ng?DA?L?1). DA was positively correlated with the presence of P. seriata-group and P. delicatissima-group and was mostly occurred during P limitation period in seawater. No DA was found in mussels that were collected during the period of DA absence in seawater. Our results suggest that temperature, salinity, inorganic and organic nutrients were significant for the seasonal dynamics of P. seriata and P. delicatissima groups, but that the P limitation was the most driving factor for DA production in these areas. The relative influence of environmental factors should be further studied to better understand the recent surfacing of massive blooms of toxigenic Pseudo-nitzschia in SW Mediterranean coast. 相似文献
309.
Diego Andrés Lugo 《Journal of Land Use Science》2020,15(2-3):343-367
ABSTRACT This article, through the use of political ecology perspectives on coercive conservation, aims to explain how in two separate Colombian Natural Parks and buffer zones, environmental policies designed to (re)take control of the frontier, have produced a similar territorial differentiation in the contention of illicit activities. Los Farallones in the Colombian Pacific and La Macarena/Puerto Rico in the Ariari region have experienced different stages of the armed conflict and are at the center of this analysis. I argue that in the contexts of both conflict escalation (1998–2007) and conflict de-escalation (2008–2016), the State in its attempt to control the frontier has not only had military intervention in areas of conservation but has also reinforced environmental programs that attack illegal mining and coca, producing both a territorially differentiated containment of illicit activities and an uneven progression of the illicit frontier. 相似文献
310.
Samuel R. Scholes Ana B. Sendova-Franks S. Tim Swift Chris Melhuish 《Behavioral ecology and sociobiology》2006,59(4):531-540
A fundamental issue of collective intelligence is whether the collective pattern or process is based on environmental information
that explicitly codes for it or arises through self-organization of the individuals. Sometimes, these alternatives occur together.
Adaptive systems may also be capable of utilizing different types of mechanism under different conditions. Sendova-Franks
et al. (Anim Behav 68:1095–1106, 2004) demonstrated evidence for a self-organization mechanism of brood sorting in the ant
Temnothorax albipennis, where the brood are sorted in a series of bands or concentric annuli that increase in size with distance from the colony
centre. The work by Cox and Blanchard (J Theor Biol 204:223-238, 2000) suggests an alternative or complementary mechanism
whereby the brood pattern is specified by the template of a CO2 gradient. Here, we test for a gaseous template as a necessary condition for brood sorting. Under the experimental condition,
we pumped the air out of the nest continuously to prevent the accumulation of any gaseous substances. We compared the brood
pattern between the experimental and control conditions according to four characteristics: mean distance from centre, mean
nearest-neighbour distance, shape and area. Under the experimental condition, the order of brood types according to the first
two characteristics was the same as in the control. The area of the brood pattern was smaller, and its shape elongated under
the experimental condition. As expected on the basis of these differences, mean distance from centre was greater and mean
nearest-neighbour distance was smaller under the experimental condition (although not statistically significantly) and by
the expected amount. We found evidence that ants avoid placing brood in the strongest airflow stream. This could explain the
reduced area and elongated shape of the brood pattern under the experimental condition. We conclude that a gaseous template
is not a necessary condition for brood sorting.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献