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Article Reference Late Subatlantic history of the ombrotrophic Misten Bog (Eastern Belgium) based on high resolution pollen, testate amoebae and macrofossil analysis
Misten Bog has through time received homogeneous pollen rain dominated successively by Fagus, Quercus and Picea. Based on the limits separating six pollen zones across nine cores, we show that the areas of major peat production have moved with time from one side of the bog to the other. The reduction of thickness of peat was strongly dependant on the proximity of peat cutting area since the 12th Century. Before the cutting, an Alnus wood that encircled the bog regressed during the Vandal Minimum (500-800 AD) and never recovered. During this age interval, testate amoebae indicate a drier period on the peat bog. From the 12th to the 14th Centuries, there was a slight increase of non arboreal pollens linked to farming. From the 14th to the 16th Centuries testate amoebae indicate again a drier period on the peat bog but whether this is linked to climate change or human pressure is unclear. From the 16th Century onwards, Sphagnum sect. Cuspidata almost disappeared but Sphagnum imbricatum persisted until the 19th Century. Pollens linked to farming culminated again during the early part of the 19th Century. High concentration of Si, Ti and N are probably linked to the increasing farming in the neighborhood as well as to industrial mining processes in the region and might have influenced these changes on the peat bog. The theory of cyclical hollow/hummock succession versus rather stationary hummocks is discussed.
Located in Library / RBINS Staff Publications
Article Reference 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).
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.
Located in Library / RBINS Staff Publications
Article Reference Mesocyclops thermocyclopoides species-group: redefinition and content
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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Article Reference Depth distribution of oligochaetes in Lake Baikal (Siberia - Russia)
In the course of a preliminary sampling program, oligochaetes were collected along two transects in soft sediments in Lake Baikal. The number of oligochaetes present in the samples was counted, without distinguishing between species. The results suggest an exponential decrease in number of individuals (N) relative to depth (11,165 N m-2 at 21 m, 265 N m-2 at 1200 m). Most oligochaetes were found in the top 7 cm of sediment. The orange colour of the sediments suggests a high oxygen availability, even at the greatest water depths.
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Article Reference Collagen Extraction from Recent and Fossil Bones: Quantitative and Qualitative Aspects
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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Article Reference New hypogean cyclopoid copepods (Crustacea) from the Yucatan Peninsula, Mexico
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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Article Reference Oligochaeta and Aphanoneura in ancient lakes: A review
By their antiquity, history, rarity, great depth in many instances and the presence of highly diverse faunas with many endemics, ancient lakes constitute ecosystems of a special nature, clearly apart from the large majority of extant lakes. While the fauna of these lakes is becoming better and better known for various animals groups, the Oligochaeta are still poorly known. Tubificidae and Naididae are found in each ancient lake. On the other hand, some families are restricted to only one lake, such as Aeolosomatidae and Proppapidae in Lake Baikal or Eudrilidae and Ocnerodrilidae (megadriles) in Lake Tanganyika, but such a distribution is probably due to a lack of knowledge or sampling biases. All ancient lakes have an endemic oligochaete fauna except Lake Kinneret (Israel). The oldest, Lake Baikal (20-25 Ma), holds the most abundant and diverse oligochaete fauna, in which species flocks are even recognizable or suspected. In contrast, the oligochaete fauna of the slightly younger Lake Tanganyika is very scarce. This is partly due to an obvious lack of studies, as the oligochaete fauna of other great African lakes is virtually unknown, but this might be the result of an environment in these lakes less favourable to oligochaetes. Some factors likely to interact with speciation in oligochaetes are discussed but nothing can be concluded to date. A recent interest in African great lakes revealed a more diverse oligochaete fauna than previously assumed but a better study of this fauna is still badly needed.
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Article Reference Pathological findings in two fin whales (Balaenoptera physalus) with evidence of morbillivirus infection
Two immature female fin whales stranded on the Belgian and French coastlines, were examined post mortem. The main gross findings were massive parasitic infestation, associated with a large thrombus in one whale, and severe emaciation. Microscopical investigations revealed multinucleated syncytia with large intranuclear inclusion bodies in various tissues, and positive immunolabelling for morbillivirus antigens. Other evidence of morbillivirus infection was provided by the demonstration of specific viral structures in syncytia and in cell cultures, and the detection of neutralizing antibodies to canine distemper virus. To the authors' knowledge, this is the first firm report of morbillivirus infection in baleen whales. (C) 2000 Harcourt Publishers Ltd.
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Article Reference Zonation and structuring factors of meiofauna communities in a tropical seagrass bed (Gazi Bay, Kenya)
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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Article Reference Morphological deformities in Chironomus riparius meigen larvae after exposure to cadmium over several generations
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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