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A reconstruction of middle Holocene alluvial hardwood forests (Lower Scheldt River, northern Belgium) and their exploitation during the Mesolithic-Neolithic transition period (Swifterbant Culture, ca. 4500 – 4000 BC).
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The analysis of a large number of charcoal fragments from fire places from a wetland camp site of the Mesolithic-Neolithic transition period (Swifterbant culture) now permits a detailed reconstruction of a middle Holocene riverine forest along the Lower Scheldt River (northern Belgium) and its exploitation between ca. 4,500 and 4,000 BC. The identified taxa point towards an alluvial hardwood forest (Querco-Ulmetum minoris Issler 1924) on the sand dune on which the camp site was situated, surrounded by alder carr. The results are compared with palynological and macrobotanical analyses from the same site and from contemporary sites within the area; the complementarity of these different types of data is discussed. The combination of all these datasets results in a detailed reconstruction of the environment and of its exploitation by the Swifterbant culture. The results also show that the Swifterbant people not only depended on these sand ridges for dry settlement locations, but also for firewood collection, gathering of edible plants and most probably for the collection of leaf fodder to feed livestock during winter time.
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What is inside this pit? Micro- and macrofaunal investigations at Chalcolithic and Early Bronze Age Ovçular Tepesi (Nakhchivan, Azerbaijan )
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The site of Ovçular Tepesi is located in the southern Caucasus (Nakhchivan Autonomous Republic). Two main archaeological phases were recognised at the settlement, namely Late Chalcolithic and Early Bronze Age. More than 1160 litres of soil samples from pits and circular stone structures belonging to the different occupation layers were processed by flotation and analysed. This paper focuses on the zoological finds from these samples, in particular the remains of fish, large mammals and micromammals, in order to determine the function of the pits and structures. Moreover, the material gives an insight into the animal economy, hunting and fishing practices of the inhabitants, as well as the local environment. Thus far, it could not be established whether the differences detected in the species composition between the phases are related to chronology alone or if other factors, such as sample sizes and type of deposits, also played a role. Fish bones were very frequent at the site with cyprinids dominating. Among the large mammals, domestic animals were the most frequent while hunted species were rare. Sheep and goat herding seems to have been the principal subsistence strategy at this site. The small mammal community is composed of synanthropic taxa and, as a consequence, the species diversity was very low (six taxa). House mouse was the most abundant in each feature on the site.
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Mesocyclops thermocyclopoides species-group: redefinition and content
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Within the genus Mesocyclops the thermocyclopoides species-group is defined on the basis of the presence of spiniform armature on the maxillar coxa. Examination of nineteen, mainly Palaeotropical species of Mesocyclops and nine representatives of the closely related genus Thermocyclops revealed, that the coxal part of the maxillar syncoxa of the species recently unified in the thermocyclopoides group is adorned with distinct rows of big spinules on its frontal surface. This character, with only one known exception in South Indian M. cf. papuensis, is absent in other species of Mesocyclops and all the Thermocyclops studied here. These species have no spinules on the maxillar coxa at all or very tiny scattered ones. © 1994 Kluwer Academic Publishers.
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Collagen Extraction from Recent and Fossil Bones: Quantitative and Qualitative Aspects
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Type I collagen is the major protein in bones. The mineral matrix protects collagen from denaturation, thus permitting the recovery of large collagen peptides from fossil bones thousands or millions of years old. Collagen peptides are more or less denatured in fossil bones, with diagenetic alteration being the major cause of such denaturation. Classical extraction methods alter the remaining large collagen peptides by extensive solubilization. A method is described here that used shorter collagen solubilization times. Resulting collagen yields are favourably compared with classical methods. The size of the large peptide (10 kDa) fraction improves considerably. Combined with a particular concentration step, the use of this shorter solubilization technique should be useful for collagen analyses that necessitate large peptides, as in the case of palaeoimmunology. © 1995 Academic Press. All rights reserved.
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New hypogean cyclopoid copepods (Crustacea) from the Yucatan Peninsula, Mexico
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Four previously unknown hypogean species of cyclopoid copepods were collected in cenotes and wells of the Yucatan Peninsula, Mexico. Diacyclops chakan sp. n. and D. puuc sp. n. differ from their congeners in combining 3-segmented swimming legs, 11-segmented antennules, and legs 1-4 endopodite segment 2 all with 2 setae. Species of Diacyclops rarely occur in tropical regions, and the Diacyclops described here are only the second and third species recorded from Mexico. The benthic D. puuc was found in the large underground reservoir of a cenote. Diacyclops chakan was encountered in such large open subterranean water basins, but more frequently and abundantly in wells. The two Mesocyclops species, M. chaci sp. n. and M. yutsil sp. n., most closely resemble their epigean benthic congener M. reidae Petkovski, but are modified by loss of some body ornament and attenuation of swimming legs and mouthparts. Mesocyclops chaci sp. n. occupies crevicular spaces (wells and small caverns). The second species, M. yutsil sp. n., with more pronounced attenuation of legs, has a planktonic life in large subterranean water volumes. The extremely attenuated appendages of both species distinguish them from all other Mesocyclops, and resemble those of the hypogean Kieferiella delamarei Lescher-Moutoué. These three species are considered as a species-flock which have radiated as specialists within a highly dynamic geomorphological environment.
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Cuticular linings and remodelisation processes in Crambe Crambe (Demospongiae: Poecilosclerida)
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The common Mediterranean sublittoral sponge Crambe crambe goes through a resting, non-feeding period with cellular restructuring which may have biological and ecological significance. This red encrusting sponge reproduces in summer and larvae released during July-August. After reproduction, from the end of August until the end of October, some specimens appeared covered with a glassy cuticle, obliterating the ostia and oscula. No water pumping and, hence, no feeding occurs during this stage. At the end of October and during November some specimens displayed a strongly hispid surface, with spicules retaining entangled debris. This hispid form is interpreted as an intermediate stage between the resting phase and the active period. SEM examination of the surface during the non-feeding period confirmed the absence of inhalant orifices and the presence of an acellular cuticle markedly different from the glycocalyx layer associated with the pinacoderm of active specimens. In some individuals, micro-organisms were found adhering to the outer side of the cuticle which were absent from the surface of active specimens. In TEM, the cuticle appeared as a complex 2.5-3μm thick structure made up of three layers: a proximal dense layer (0.06-0.12μm), an intermediate amorphous layer (0.15-0.3μm), and an outer granular layer also of variable thickness (more than 2μm) which progressively disintegrated. Collagen debris appeared between the proximal and intermediate layers. The zone beneath this triple-layered cuticle was either completely devoid of cells or showed scarce degenerating cellular components (mainly from pinacocytes and spherulous cells), and sparse collagen fibrils. The choanosome appeared rather disorganised, with most choanocyte chambers disintegrated, with abundant phagocytosing archeocytes, sclerocytes, spherulous cells, degenerated cells and cell debris. Later in the season the cuticle appeared broken in many places. It was cast off and a new pinacoderm with ostia developed below; filtering activity of the sponges resumed. Spicules, previously protected by the cuticle, were uncovered, giving rise to a hispid phase. Subsequently the emergent spicules were cast off and smoothness of the sponge surface was restored. These changes in sponge cell structure and activity may be explained as reorganisation processes after reproduction, but other causes, such as adverse water temperature, may have similar effects.
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Growth and regeneration rates of the calcareous skeleton of the Caribbean coralline sponge Ceratoporella nicholsoni: A long term survey
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The growth rate of the aragonitic skeleton of the Caribbean 'sclerosponge' Ceratoporella nicholsoni has been studied by in situ staining of specimens with calcein in a reef tunnel, 28m depth, near Discovery Bay, Jamaica. Experiments were performed up to five times from 1984 to 1997 on a population of 10 specimens ranging from 10-20cm maximum diameter. In each experiment small skeletal samples were removed from the periphery of sponges, and specimens were left in place for further studies on growth and regeneration. Perpendicular sections, ground to a thickness of about 10μm, were photographed by fluorescence microscopy. Annual skeletal growth rates were calculated from measurements of the linear extension between calcein stained lines along growth axes. Data indicate that although average annual growth rates remained in the same range for different periods (214.6±54.5-233.3±33.0μm yr -1), significant differences occurred from one individual to another within the same period. The annual growth rate of a given individual also varied significantly in time (191.1±30.0-269.9±37.0μm yr -1). A second population of smaller individuals, measured after a single period of one year, revealed a strikingly lower average annual growth rate (124.4±35.0μm yr -1). Regeneration of the skeleton of injured specimens was also characterised by an initial slower growth rate. Nevertheless, after the first year, it was comparable to normal growth, and exceeded it slightly thereafter. This first long term study of Ceratoporella provides important information on the variability in growth rates, with implications on the use of sclerosponges as paleoenvironmental proxies.
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Two new living species of Loxotaphrus (Gastropoda: Cancellariidae: Plesiotritoninae) from Queensland, Australia and Mozambique, East Africa
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Until now, the only living species assigned. to the cancellariid genus Loxotaphrus Harris, 1897 was the West African species L. deshayesii (Duval, 1841). Two new living species are described here, L. limpusi n. sp., from the Swain Reefs, Queensland, and L. rosadoi n. sp., from off southern Mozambique. L. limpusi most closely resembles the type species of the genus, L. variciferus (Tate, 1888) (Miocene, southern Australia). Although L. rosadoi resembles L. variciferus and L. limpusi more closely than it does L. deshayesii, it differs from all other species, assigned to Loxotaphrus in having weak sculpture, apart from the prominent, sharp nodules around the peripheral keel.
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Zonation and structuring factors of meiofauna communities in a tropical seagrass bed (Gazi Bay, Kenya)
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This study deals with the relation between tropical meiofauna and environmental variables by comparing the 'benthic' (i.e. in the bare sediment adjacent to seagrass plants) and the 'epiphytic' (i.e. in samples including seagrass plants) meiofauna associated with five seagrass species from the high intertidal to the high subtidal zone in Gazi Bay (Kenya), Ordination and variance analysis revealed three distinct 'benthic' and two 'epiphytic' meiofauna assemblages. These assemblages corresponded entirely with those identified for the seagrass species: a high intertidal pioneer association (Halophila ovalis/Halodule wrightii), an intertidal climax assemblage (Thalassia hemprichii) and a high subtidal pioneer association (Halophila stipulacea/ Syringodium isoetifolium). These data support the hypothesis that meiofaunal communities correspond to the characteristic zonation of the seagrass vegetation in Gazi Bay. In beds of the pioneer seagrass species, the close relationship between sediment characteristics and both 'benthic' and 'epiphytic' meiofauna communities suggests that these pioneer communities were mainly driven by physical factors. The 'benthic' communities adjacent to the climax seagrass species T. hemprichii were more structured by biogenic factors, e.g. \% TOM, chlorophyll a and c, fucoxanthin, habitat complexity and growth form of the seagrass species. For its associated 'epiphytic' meiofauna the latter conclusion was even more striking. These data corroborate the importance of physical factors in disturbed environments (intertidal zone, near pioneer seagrasses) and of biotic factors in more stable conditions (subtidal zone, near climax seagrasses). © 2001 Elsevier Science B.V.
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Morphological deformities in Chironomus riparius meigen larvae after exposure to cadmium over several generations
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In order to test the potential of chironomid deformities for biomonitoring, induction of morphological deformities in Chironomus riparius larvae was assessed after chronic exposure (static with renewal) of eggs and subsequent instars to sublethal nominal cadmium concentrations of 0, 3 (NOEC), 9 (intermediate) and 27 (chronic LC'50) μg Cd 1-1 during 7 to 10 generations. Deformities which could be associated with an indirect or direct cadmium effect were split medial mentum teeth (more frequent in 9 and 27 μg Cd 1-1) and premandible deformities (especially in 3 μg Cd 1-1). The control contained more larvae with additional teeth in mentum and mandible than the metal-exposed conditions. In the 9 μg Cd 1-1 condition the frequencies of larvae with split medial mentum teeth increased in the last four generations, to reach 40\%. The unpredictability of fluctuations of deformity frequencies over the generations was associated with parental effects and experimental manipulation. The deformity percentages correlated positively with the mortalities and could be related to the induction of tolerance to cadmium, as was concluded on the basis of life cycle analysis in a previous paper. This experiment demonstrated a concentration-response relationship between deformities and sublethal levels of cadmium. However, the observed generation fluctuations caution for (1) the use of single-generation experiments for defining ecotoxicological threshold values, and (2) experimentally induced genetical drift in multi-generation experiments.
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