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1.
Four phases are distinguished in the Mid-Holocene evolution of the southwestern Doñana National Park (SW Spain), based on the multidisciplinary study of sediments in drill cores. In the oldest phase (> 5500-5400 cal. years BP), a coastal, brackish lagoon occupied the central part of the study area, partly enclosed by the Doñana spit and limited by fluvial levees. An evolution from subtidal to intertidal conditions characterized the areas located close to the inner side of the Doñana spit during the same phase. The following phase (∼5400-5200 cal. years BP) is characterized by a high-energy event (tsunami?), which caused the breakthrough of the Doñana spit and the creation of new littoral strands in the inner areas. In the first period of the third phase (∼5200-4200 cal. years BP), estuarine infilling was probably the dominant process, with the accumulation of phyllosilicate-rich clays in the lagoon bed. This was followed by a renewed phase of instability (∼4200-4100 cal. years BP) indicated by the presence of fine storm-lain deposits and thicker, probably tsunami-induced shelly deposits. The last phase (∼4100-3700 cal. years BP) comprises: a) an infilling period, with a diminution of the marine influence; and b) two new high-energy events, which caused the erosion of the Doñana spit and the creation of new cheniers.In the last 7000 years, the comparison of these results with a revision of both geological and historical records has revealed the occurrence of twenty tsunamis (at least) during this period in Portugal and southern Spain. Evidences of these high-energy events are washover fans, bioclastic coarse-sized layers within salt marsh deposits or the presence of giant boulders and pebbles. The determination of the recurrence period is very difficult owing to the very scarce data, although our data and other authors do not discard a possible periodicity of 2000 years for a cycle of two events separated by 300-400 years.  相似文献   

2.
The changes in caddisfly community structure and composition in the Sil River basin (NW Spain), associated with a gradient in natural conditions and a succession of alterations induced by human activity (mainly urban wastes and coal mining), were studied. Twenty-nine Trichoptera taxa belonging to 11 families were collected. The community diversity analysis showed important spatial differences from source to mouth. Towns and, above all, coal mines produced an increase in sulphate and chloride concentrations and conductivity, which adversely affected the trichopteran assemblages. A stepwise regression model, which introduced sulphate and chloride as variables, explained the changes in diversity produced in the basin (r=0.837, p< 0.01). The lowest diversity and richness values were recorded in the rivers suffering the greatest impact from coal mining or urban wastes. The heterogeneity values of the communities for the main rivers were clearly different. The greatest community heterogeneity corresponded to the main axis of the basin and was explained by spatial variability in water chemical composition. No relation was detected between structural changes at spatial level and geographical distance, such that pollution processes basically controlled the dynamics of the Trichoptera communities. Partial-CCA using distance from the source as a covariable revealed alkalinity and urban and mining-derived pollution as the main factors influencing caddisfly distribution. However, an ordination of sites in relation to the corresponding vectors did not fully agree with the chemical characteristics of the water. The species composition of the Trichoptera communities, therefore, did not seem to be good indicators of the chemical features of the rivers. The structure of the community (as expressed by richness and the Shannon index) appeared to be the better indicator of pollution.  相似文献   

3.
The hydropsychids of two Mediterranean river basins in southern Spain (Guadaira and Guadalete) were investigated from January 1988 to January 1989. The distribution of hydropsychids along an environmental gradient related to altitude varied depending on species. Two distinct species assemblages were observed. one located in the lower altitude sites (the “downstream assemblage” comprising Hydropsyche pictetorum, Hydropsyche exocellata and Cheumatopsyche lepida) and the other in the upper-most areas (the “upstream assemblage” comprising Hydropsyche punica, Hydropsyche infernalis, Hydropsyche instabilis), which displayed a statistically significant preference for this type of habitat. Finally, H. pictetorum, selected the lowest sites. From a temporal point of view most species displayed a high variability in density dynamics between sites, suggesting a strong plasticity in life-cycle phenology.  相似文献   

4.
A quantitative taphonomic analysis of the fossil assemblages, together with a sedimentary study of the Pliocene deposits of the Vejer Basin (Cádiz, Spain), has been carried out. This multidisciplinary analysis has allowed us to establish with great precision the palaeoenvironmental conditions under which these materials were formed. The Pliocene deposits can be divided into three units, named from bottom to top: Unit 1, Unit 2 and Unit 3. Unit 1 is formed of medium-to-coarse-grained sands at the base, corresponding to subtidal bar deposits. At the top, the sands become coarser, and beach and littoral dunes were formed. Within these sedimentological contexts, the fossil remains exhibit a strong degree of taphonomic destruction due to high hydrodynamic energy. Unit 2, consisting of clays, corresponds to deposits formed in a protected coastal bay. A low-energy environment allowed the fossils to maintain a good state of conservation and even thin-shelled bivalves with a delicate ornamentation are preserved. Unit 3 comprises highly bioclastic sands and calcarenites-calcirudites. This unit displays a shallowing upwards trend, passing from deposits generated under shallow subtidal conditions in the lower part to materials deposited on beaches and coastal dunes in the upper part. Under these conditions, the fossil remains show a high degree of taphonomic destruction. In Units 1 and 3, the fossils are mainly accumulated in horizontal beds, with extensive lateral continuity and with erosive bottoms and graded tops. These accumulations of fossils are interpreted as tempestites. As compared with the fossils preserved in surrounding sediments, the taphonomic attributes of these bioclasts suggest a superposition of the background and event processes. During normal conditions, the high energy of the littoral environments produced a strong degree of taphonomic destruction. During storm events, a mixture of taphonomic attributes was produced: high fragmentation and disarticulation and little abrasion and edge rounding of the fragments. This mixture was a consequence of sudden burial after storms, which prevented long periods of exposure of the bioclasts in the taphonomically active zone. Three taphofacies models are proposed, based on taphonomic attributes of fossils contained in the different units: inner-shelf taphofacies, protected shallow-lagoon taphofacies and storm bed taphofacies.  相似文献   

5.
《水生昆虫》2012,34(2):23-31
The Balkan Peninsula is known for its high species diversity, but it is also one of the least known areas of Europe. Many previously inaccessible regions lack reliable faunistic records. There are especially few data available for the highly diverse aquatic insects of the region. To help fill the gap, we conducted an extensive survey to map the Trichoptera fauna of the Republic of Kosovo, an area where faunistic records are extremely scarce. Adult specimens were collected during 2009 and 2010, with light traps and entomologic nets. Of 84 Trichoptera species identified from the 21 investigated stations, 15 belong to the genus Rhyacophila. This makes the genus the most species-rich in Kosovo. Rhyacophila fasciata and R. tristis are widespread in many streams and rivers all over the country, while R. balcanica, R. trescavicensis, R. obtusa and R. bosnica have limited distribution. Ten Rhyacophila species presented in this paper are recorded for the first time on the area of Kosovo. We also provide new data for the disjunctive distribution of R. palmeni in south-eastern Europe, from Kosovo and Croatia.  相似文献   

6.
Japanese species of the genus Dolophilodes subgenus Dolophilodes are revised taxonomically. Seven described species are recognized: D. japonicus (Banks), D. shinboensis (Kobayashi), D. auriculatus Martynov, D. nomugiensis (Kobayashi), D. babai (Kobayashi), D. iroensis (Kobayashi) and D. commatus (Kobayashi). In addition, two new species, D. angustatus and D. dilatatus, are described. Males of all nine species and females of all but D. babai are described and illustrated. The subgenus Hisaura Kobayashi is synonymized under the subgenus Dolophilodes. Three synonymies of species proposed are Wormaldia triangulata Kobayashi under D. nomugiensis, D. kunashirensis Ivanov under D. iroensis and Sortosa kaishoensis Kobayashi under D. commatus.  相似文献   

7.
Twenty-eight species of nine families of caddisflies (Trichoptera) were identified in 170 samples taken over an 8-month period from five emergence traps placed on a second-order, forested, cold-stenothermal stream on the Niagara Escarpment, Ontario, Canada.A mean of 980.9 caddisflies m–2 of streambed was obtained over the entire sampling period. Eleven common species accounted for 92.8% of the total emergence with specific proportions ranging from 23.8% (Wormaldia moesta) to 0.11 % (Rhyacophila sp.). The use of various kinds of traps in other studies and their effects on the detection of species composition and abundance are discussed and compared with the present study.Although the distributions of all the common species were invariant over time, four species showed low to high degrees of patchiness in the streambed; the other seven common species were uniformly distributed. However, a large residual variance suggested a subtle mechanism of microhabitat selection by the larvae and (or) pupae, not detectable by even the small emergence traps used.Both sexes of 15 species, only males of 4 and only females of 9 species were collected. Eight of the eleven common species showed significant departures from a balanced sex ratio and five exhibited a protandry of from 1 to 3 weeks. Neither this study nor others have been able to establish a predictable pattern of sex ratios in Trichoptera.The emergence periods and patterns of the eleven common species are described and compared with other studies. Of these common species, one emerged in the spring, seven during the summer and three during the late summer or early fall. Ten species had a short emergence period with a distinct peak and a significantly skewed pattern. One species,Parapsyche apicalis, exhibited a prolonged emergence period, no distinct peak and a significantly platykurtotic2 pattern. With the exception ofLepidostoma sp. A, the emergence patterns of the common species were unimodal.  相似文献   

8.
Houghton DC 《ZooKeys》2012,(189):1-389
The caddisfly fauna of Minnesota contains at least 277 species within 21 families and 75 genera. These species are based on examination of 312,884 specimens from 2,166 collections of 937 Minnesota aquatic habitats from 1890 to 2007. Included in these totals is my own quantitative sampling of 4 representative habitat types: small streams, medium rivers, large rivers, and lakes, from each of the 58 major Minnesota watersheds from June through September during 1999-2001. All species are illustrated herein, and their known Minnesota abundances, distributions, adult flight periodicities, and habitat affinities presented. Four species: Lepidostoma griseum (Lepidostomatidae), Psilotreta indecisa (Odontoceridae), and Phryganea sayi and Ptilostomis angustipennis (Phryganeidae) are added to the known fauna. An additional 31 dubious species records are removed for various reasons. Of the 5 determined caddisfly regions of the state, species richness per watershed was highest in the Lake Superior and Northern Regions, intermediate in the Southeastern, and lowest in the Northwestern and Southern. Of the 48 individual collections that yielded >40 species, all but 1 were from the Northern Region. Many species, especially within the families Limnephilidae and Phryganeidae, have appeared to decrease in distribution and abundance during the past 75 years, particularly those once common within the Northwestern and Southern Regions. Many species now appear regionally extirpated, and a few have disappeared from the entire state. The loss of species in the Northwestern and Southern Regions, and probably elsewhere, is almost certainly related to the conversion of many habitats to large-scale agriculture during the mid-20th century.  相似文献   

9.
The biochronological age of the small-mammal populations of Los Gargantones 1, 2 and La Celia (upper Miocene, La Celia sub-basin, Murcia, Spain) is re-interpreted. The presence in Los Gargantones of Occitanomys adroveri, Parapodemus barbarae, Parapodemus cf. gaudryi, Huerzelerimys turoliensis, Atlantoxerus cf. adroveri, and Alilepus evidences a correlation to MN12 (∼7.5–7 Ma) rather than to MN11 (∼9–7.5 Ma), as inferred previously. The assemblage corresponds to that of the more eastern, near-coast sites of Crevillente 8 and 15, situated in the Alicante area. The stratigraphically highest site of La Celia contains Hispanomys adroveri, a species also indicative of MN12. The presence of Castromys cf. littoralis together with an advanced O. adroveri points to a slightly younger age than that of Los Gargantones, approaching that of MN13 sites. The assemblage best matches that of Crevillente 17. Other species described in this paper are Prolagus crusafonti, Prolagus sp., Parasorex cf. ibericus, Panelimnoecus cf. repenningi, and Blarinella aut Petenyia sp. indet.  相似文献   

10.
The Balkan Peninsula is one of three major European refugial areas. It has high biodiversity and endemism, but data on the age and origin of its fauna, especially endemics, are limited. Mitochondrial sequence data (COI and 16S genes) were used to study the population structure and phylogeography of the caddisfly Drusus croaticus and the phylogeny and divergence of seven other Drusus species, mostly range-restricted endemics of the Dinaric region of the Balkan Peninsula. The divergence of D. croaticus populations in Croatia and allopatric Drusus species in Bosnia dated to the Pleistocene, showing the importance of this time period for the origin and diversification of Balkan endemic taxa. The divergence of more distantly related species dated to the Late Miocene/Early Pliocene. Population genetic and phylogeographic analysis of 115 individuals from 11 populations of D. croaticus revealed a high level of genetic differentiation and absence of gene flow between populations separated by more than 10 km. The existence of allopatrically fragmented lineages in D. croaticus and the endemic Bosnian species is most likely the result of long-term isolation in multiple microrefugia, probably due to the specific habitat requirements and life-history traits of Drusinae coupled with the topographic complexity and historical changes in geomorphology of the region. Overall, these findings shed light on the processes generating the high genetic complexity of this refugial region that parallels the 'refugia within refugia' pattern widely reported from the Iberian refugium.  相似文献   

11.
Pedro C&#;ozar 《Facies》2003,49(1):1-18
Summary Microfacies analysis of over 1800 standard thin-sections of upper Viséan and Pendleian-aged platform limestones from southwestern Spain (Guadiato area) shows that foraminiferal assemblages contain many allochthonous specimens. The analysis of the cementation, recrystallization, abrasion, bioerosion, encrustation, dissolution, taphonomic distortion, orientation and sorting allow the recognition of eight taphofacies. They are based on the taphonomic features observed within the foraminiferal assemblages, which reflect the environmental conditions in which foraminifera were sedimented as well as about early diagenesis. The environmental conditions may be ascertained from the analysis of the biostratinomic processes, which comprise the energy, waves, tides, redox conditions, etc. The mechanisms of taphonomic alteration may be quantified, and thus the appearance or absence of these alterations may be used to define taphofacies of shallow- and deep-water environments, such as those from tidal flat, shoal, outer platform, microbial mound or slope. Moreover, the relationship among these taphofacies also helps to define depositional mechanisms and products, such as debris flows or olistolites.  相似文献   

12.
The relationship between caddisfly assemblage structure and four selected environmental variables (substrate, water depth, flow type and amount of the coarse particulate organic matter) was investigated in a Slovenian lowland stream. Caddisflies were sampled at four stream reaches according to selected microhabitat types. All together, 168 quantitative samples were taken at 21 sampling points between October 1998 and July 1999. Of 48 collected species, 30 were included in the analysis. Significant correlation was observed between species and environmental variables. As a complement to a CCA biplot representation, species assemblages within the community were also determined using cluster analysis. Nine groups and subgroups were established. Most caddisfly species prefer coarse substrate in shallow water (5–10 cm) with chute water flow, whereas few species were found on fine substrate in deep water. A significant positive correlation was found between mean substrate size and total number of species, and between indices of species richness and diversity, whereas depth did not show any correlation with these parameters. Seven species were found mostly in marginal habitats, whereas four (Potamophylax rotundipennis, Anabolia furcata, Athripsodes bilineatus and Lithax obscurus) did not show any strong preferences for selected parameters. In addition, habitat preferences were associated with the feeding types of the caddis larvae.  相似文献   

13.
The nematodes Cucullanus hians, Cucullanus longispiculum , Cucullanus minutus , Contracaecum sp., Anisakis simplex , and Cristitectus congeri , the cestodes Grillotia , sp. and Scolex pleuronectis , and the acanthocephalan Acanthocephaloides propinquus , were recorded from 251 conger eels from the Muros and Arousa estuaries, north-west Spain. Several species were useful as tags and showed that conger eels in both estuaries and also on the continental shelf belong to separate populations. The nematode C. congeri , shows a distribution pattern indicating that the trophic chains involving the conger eel in each estuary are probably different. The species composition and abundance of the nematode, cestode and acanthocephalan fauna of Conger conger , on the north-west Spanish coast may depend more on population isolation and variations in trophic chains between the sites studied than on the particular environmental conditions of the sites.  相似文献   

14.
Alterosa Blahnik, 2005 contains 35 described species distributed in southern and southeastern Brazil. Three new species of Alterosa from northeastern Brazil are described and illustrated, Alterosa amadoisp. n., Alterosa castroalvesisp. n. and Alterosa caymmiisp. n., the first records of the genus from northeastern Brazil. An identification key for all known species of the genus is also presented.  相似文献   

15.
Between 2000–2002, the structure of communities of lepidopteran larvae was studied in leaf bearing crowns of Quercus cerris in the central and northern part of the Malé Karpaty Mts (SW Slovakia). Caterpillars were collected using the beating method in four study plots. In total, 58 species were found. The families Geometridae, Noctuidae and Tortricidae comprised the highest number of species found. The family Geometridae comprised the highest number of pests. The most abundant species for individual plots were Lymantria dispar, Operophtera brumata, Ypsolopha alpella and Cyclophora ruficiliaria. Most of the recorded species belonged to the trophic group of generalists (39 species). Shannon-Wiener’s diversity index and Pielou’s equitability (evenness) value indicated there were marked differences between the Horny háj study plot (an insular forest with ants as the predators of caterpillars) and other plots. The main ecological gradient along DCA-1 related to the host specificity of caterpillars and consisted of three groups: (a) polyphagous species; (b) specialist species feeding chiefly on oaks or exclusively on oaks and (c) species preferring some oak species, mainly Q. cerris. The fragmentation of growth was identified along DCA-2.  相似文献   

16.
Here we report the development of 10 microsatellite loci for the alpine caddisfly, Allogamus uncatus. Polymorphism as detected in 24 individuals ranged from three to 17 alleles per locus, and observed heterozygosity ranged from 0.087 to 0.864. These primers will enable research on the genetic population structure of this species, the extent of gene flow among alpine permanent and temporary streams, and the genetic consequences of extinction/recolonization events.  相似文献   

17.
Integrated analysis of a 50-m long sedimentary core collected in the central part of the Odiel estuary (SW Atlantic coast of Spain) allows delineation of the main paleoenvironmental changes that occurred in this area during the Holocene. Eight sedimentary facies were deposited in the last ca. 9000 years BP, confirming a transgressive-regressive cycle that involves the transition from fluvial to salt marsh deposits with intermediate marine tidal deposits. A storm event is detected at ca. 5705 14C years BP (mean calibrated age) with distinct lithostratigraphical, textural, geochemical, and palaeontological features.  相似文献   

18.
Determining the ecological status of river ecosystems should be based on reference (near-natural) conditions and on the use of their biological communities. Identifying reference conditions is particularly difficult in largely disturbed watersheds, such as those of agricultural landscapes. Ecotype reference sites and their characteristic diatom communities were identified in the Guadiana watershed. Three different ecotypes were defined: rivers with siliceous bedrocks, upper watershed calcareous rivers, and mainland watercourses. Thirteen key stressors divided in four categories (channel alteration, hydrological pressure, pollution pressure, and river habitat pressure) were used to select reference sites in each ecotype. Multivariate techniques were used to describe type-specific reference diatom community in each ecotype. Because of the difficulty to define reference sites in the mainland watercourses, some sites were selected under the criterion of minimum impacted sites. Diatoms inhabiting sites included species tolerant to high nutrient concentration and mineralized waters, like Nitzschia inconspicua, Gomphonema parvulum, and Navicula veneta. These taxa defined the best condition (near-to-reference) in an ecotype highly impacted by human activities, the best possible in the long-lasting impaired conditions in the large river watercourses in agricultural landscapes.  相似文献   

19.
In this data paper, a dataset of passerine bird communities is described in Sierra Nevada, a Mediterranean high mountain located in southern Spain. The dataset includes occurrence data from bird surveys conducted in four representative ecosystem types of Sierra Nevada from 2008 to 2015. For each visit, bird species numbers as well as distance to the transect line were recorded. A total of 27847 occurrence records were compiled with accompanying measurements on distance to the transect and animal counts. All records are of species in the order Passeriformes. Records of 16 different families and 44 genera were collected. Some of the taxa in the dataset are included in the European Red List. This dataset belongs to the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.  相似文献   

20.
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