The ignored but common nemertine Psammamphiporus elongatus from the Galician beaches (Spain), affected by the Prestige oil spill     

Alfonso Herrera-Bachiller  Pedro García-Corrales  Carmen Roldán  & Juan Junoy 《Marine Ecology》2008,29(S1):43-50

Nemerteans have been recorded in several studies of the sandy beaches, but usually these specimens have been only regarded as members of the Phylum, with no attempt at identification at any taxonomic level. This lack of identification is partly because of the sampling procedures used to collect beach macroinfauna. Nemerteans are fragile and need special care. They must be isolated and observed in vivo before using histological procedures, which must be employed for the taxonomical studies. This study deals with a sandy beach hoplonemertean, Psammamphiporus elongatus ( Stephenson 1911 ), only known for seven specimens from the Firth of Clyde (UK). This species is recorded for the first time from the Galician sandy beaches (NW Spain) where it reaches its maximum abundance. The species is described and illustrated and new data on its morphology and ecology are provided. The species was apparently affected by the 'Prestige' oil spill, and would be a good indicator of beach quality.  相似文献   

The trade of live crustaceans in Portugal: space for technological improvements     

Barrento  Sara; Marques  Antonio; Pedro  Sonia; Vaz-Pires  Paulo; Nunes  Maria Leonor 《ICES Journal of Marine Science》2008,65(4):551-559

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Separate and interactive effects of eutrophication and climate variables on the ecosystem elements of the Gulf of Riga   总被引：1，自引：0，他引：1  

Jonne Kotta  Ilmar Kotta  Mart Simm  Maria Pllupüü 《Estuarine, Coastal and Shelf Science》2009,84(4):509-518

There is currently a critical knowledge gap in how eutrophication and climate variables separately and interactively impact the dynamics of marine ecosystems. Based on long-term monitoring data we quantified the separate and combined impacts of nutrient loading, temperature, salinity, and wind conditions on zooplankton, zoobenthos and fish inhabiting a brackish water ecosystem in the Gulf of Riga. Changes in zoobenthos communities and herring stock were largely explained by climate variables. Zooplankton species were related to both eutrophication and climate variables, and models combining all environmental variables explained additional variation in zooplankton data compared to the separate models of climate and eutrophication. This suggests that zoobenthos communities and herring stock are largely driven by weather conditions, whereas the combined effect of weather and nutrient loads are likely the cause for dynamic zooplankton communities in the Gulf of Riga.  相似文献   

Conservation Priority Index for Estuarine Fish (COPIEF)     

Paulo Branco  Jos Lino Costa  Pedro Raposo de Almeida 《Estuarine, Coastal and Shelf Science》2008,80(4):581-588

Public awareness regarding environmental issues has increased in recent decades. The increasing number of impact assessment studies, management and conservation plans, as well as ecological monitoring studies, demand new and more efficient techniques. Indices are an important tool to aid biologists in these studies and should allow an easier comprehension of the data by managers, decision-makers and the general public. This study presents the first multi-metrical index able to establish a hierarchical ordination of the conservation priority of the estuarine fish species using 72 species from 16 estuarine systems (W and S coasts of Portugal). The index is composed of 10 metrics, comprising species life traits, distribution and population trends. The information needed to score each metric was gathered from the published literature and the index validation was done by external means. This methodology allowed the definition of those fish species most in need of conservation planning, and those less prone to extinction in Portuguese estuarine systems. The proposed index fills a gap in our knowledge and provides a useful tool to the scientific community and to the decision-makers, being a breakthrough in the field of conservation planning of estuarine fish species.  相似文献   

Quantitative morphometric analysis of the Jama River profile in a tectonically active margin (Northwestern Ecuador)     

Pedro S.B.REYES  Mauricio E.VALAREZO  Jenry CóRDOVA  Fran?ois A.MICHAUD  Camilo ZAPATA 《山地科学学报》2018,15(5):966-975

The longitudinal profile of a river channel can be described in function of mathematical expressions. The logarithmic fit is the most used method to describe the relative equilibrium of a channel elevation profile. Rivers showing zones of high channel gradient and convex-upward profiles can be evaluated in function of the offset distance with respect to the logarithmic curve. The Jama River profile has been constructed using differential GPS data for the downstream reach and 4-m-grid DEM data base for the remaining headward profile. The resulting longitudinal profile shows a prominent knickpoint of about 80 m in elevation characterized by sharp local convexity. The offset distance in vertical direction from the logarithmic plot is interpreted as the successive accumulation of multiple uplift episodes associated with the Jama Fault System activity. The horizontal offset is suggested to represent the remaining retreated distance for the upstream propagation of the Jama knickpoint. The highly resistant Cretaceous rocks outcropping along the Jama knickpoint reach acts as an inflection point between two subprofiles that show well-fitted logarithmic curves, thereby representing a temporary partitioned equilibrium along the Jama River profile.  相似文献   

Plant diversity and community structure of Brazilian <Emphasis Type="Italic">Páramos</Emphasis>     

Prímula Viana Campos  Pedro Manuel Villa  Jaquelina Alves Nunes  Carlos E.G.R. Schaefer  Stefan Porembski  Andreza Viana Neri 《山地科学学报》2018,15(6):1186-1198

In Eastern South America, high altitude grasslands represent a mountain system that has a high number of endemic species. However, studies on the ecology of plant communities in these environments remain scarce. We aimed to evaluate the patterns of biodiversity and structure of plant communities from rocky outcrops in high altitude grasslands of three areas at the Caparaó National Park, southeastern Brazil, by sampling 300 randomly distributed plots. Then, we compared the floristic composition, relative abundance, and biological and vegetation spectra among areas. We classified species as endemic and non-endemic and verified the occurrence of endangered species. Species richness was evaluated by rarefaction analysis on the sampling units. The importance value and species abundance distribution (SAD) models were assessed. We also performed an indicator species analysis. We sampled 58 species belonging to 49 genera and 32 families. The number of species decreased with increasing altitude, with significant differences being observed among areas regarding richness, abundance, and cover. Of the total number of species, 10 are endemic to the Caparaó National Park and 17 are listed on the Brazilian Red List of endangered species. The dominant families on all peaks were Asteraceae and Poaceae. The SAD models showed lognormal and geometric distributions, corroborating the fact that 10 species that were common to all three areas were also the most dominant ones in the communities and showed the highest importance values, which ranged between 35% and 60%. Indicator species analysis revealed that 28 species (48.27%) were indicators. Of these, 42.85% had maximum specificity, meaning that they occurred only in one area. Thus, the number of species per life form ratio was similar among areas, yet vegetation spectra differed, especially for hemicryptophytes. The altimetric difference among the areas showed to be a very important driver in the community assembly, influencing the evaluated variables, however, other drivers as soil depth, slope and water could also influence the community structure on a smaller and local spatial scale.  相似文献   

Nonlinear adaptive control of an underwater towed vehicle     

Francisco Curado Teixeira  António Pedro Aguiar 《Ocean Engineering》2010,37(13):1193-1220

This paper addresses the problem of simultaneous depth tracking and attitude control of an underwater towed vehicle. The system proposed uses a two-stage towing arrangement that includes a long primary cable, a gravitic depressor, and a secondary cable. The towfish motion induced by wave driven disturbances in both the vertical and horizontal planes is described using an empirical model of the depressor motion and a spring-damper model of the secondary cable. A nonlinear, Lyapunov-based, adaptive output feedback control law is designed and shown to regulate pitch, yaw, and depth tracking errors to zero. The controller is designed to operate in the presence of plant parameter uncertainty. When subjected to bounded external disturbances, the tracking errors converge to a neighbourhood of the origin that can be made arbitrarily small. In the implementation proposed, a nonlinear observer is used to estimate the linear velocities used by the controller thus dispensing with the need for costly sensor suites. The results obtained with computer simulations show that the controlled system exhibits good performance about different operating conditions when subjected to sea-wave driven disturbances and in the presence of sensor noise. The system holds promise for application in oceanographic missions that require depth tracking or bottom-following combined with precise vehicle attitude control.  相似文献   

Energy balance and evaporation loss of an agricultural reservoir in a semi‐arid climate (south‐eastern Spain)     

B. Gallego‐Elvira  A. Baille  B. Martín‐Górriz  V. Martínez‐Álvarez 《水文研究》2010,24(6):758-766

A typical agricultural water reservoir (AWR) of 2400 m² area and 5 m depth, located in a semi‐arid area (southern Spain), was surveyed on a daily basis for 1 year. The annual evaporation flux was 102·7 W m^?2, equivalent to an evaporated water depth of 1310 mm year^?1. The heat storage rate G exhibited a clear annual cycle with a peak gain in April (G ～ 45 W m^?2) and a peak loss in November (G ～ 40 W m^?2), leading to a marked annual hysteretic trend when evaporation (λE) was related to net radiation (R_n). λE was strongly correlated with the available energy A, representing 91% of the annual AWR energy loss. The sensible heat flux H accounted for the remaining 9%, leading to an annual Bowen ratio in the order of 0·10. The equilibrium and advective evaporation terms of the Penman formula represented 76 and 24%, respectively, of the total evaporation, corresponding to a annual value of the Priestley–Taylor (P–T) coefficient (α) of 1·32. The P–T coefficient presented a clear seasonal pattern, with a minimum of 1·23 (July) and a maximum of 1·65 (December), indicating that, during periods of limited available energy, AWR evaporation increased above the potential evaporation as a result of the advection process. Overall, the results stressed that accurate prediction of monthly evaporation by means of the P–T formula requires accounting for both the annual cycle of storage and the advective component. Some alternative approaches to estimating R_n, G and α are proposed and discussed. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

The last deglaciation in the Picos de Europa National Park (Cantabrian Mountains,northern Spain)     

Ana Moreno  Blas L. Valero‐Garcés  Montserrat Jiménez‐Sánchez  María José Domínguez‐Cuesta  M. Pilar Mata  Ana Navas  Penélope González‐Sampériz  Heather Stoll  Pedro Farias  Mario Morellón  J. Pablo Corella  Mayte Rico 《第四纪科学杂志》2010,25(7):1076-1091

A sedimentological and geochemical study of the Lago Enol sequence (Cantabrian Mountains, northern Spain), together with detailed geomorphological mapping, provides a first record of glacier evolution and climate change over the last 40 ka in the Picos de Europa National Park. The Enol glacier retreated from its maximum extent prior to 40 ka BP as demonstrated by the onset of proglacial lacustrine sedimentation in two glaciated depressions: the Comella hollow to the north (before 40 ka BP) and the Lago Enol (before 38 ka BP). These results support previous evidence that the maximum extent of southern European glaciers occurred earlier than in northern Europe. Alternation of homogeneous and laminated proglacial sediments during the glacier retreat illustrate a dynamic glacial evolution during the Marine Isotope Stage (MIS) 3 (40–26 ka BP). A slight warming is detected at 26 ka ago with the change from proglacial sediments (in a lake located in contact to the glacier) to glaciolacustrine sedimentation (in a non‐contact or distal lake). Finally, the onset of organic‐rich sediments took place at 18 ka ago. This last transition occurred in two phases, similarly to the North Atlantic Last Termination, suggesting a link between North Atlantic Deep Water formation oscillations and palaeohydrological variability in the Cantabrian Mountains. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Luminescence dating of Pleistocene alluvial sediments affected by the Alhama de Murcia fault (eastern Betics,Spain) – a comparison between OSL,IRSL and post‐IR IRSL ages     

Reza Sohbati  Andrew S. Murray  Jan‐Pieter Buylaert  Maria Ortuño  Pedro P. Cunha  Eulàlia Masana 《Boreas: An International Journal of Quaternary Research》2012,41(2):250-262

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