Environmental determinants of fish abundance in the littoral zone of gravel pit lakes

The type and extent of habitats along the shoreline specify the distribution of fish in the littoral zone of lakes, but effects are likely species and size-specific and might be overwhelmed by lake-level environmental factors that drive fish abundance (e.g. trophic state). We applied a replicated transect-sampling design by electrofishing assessing fish abundance and distribution along the banks of 20 gravel pit lakes in Lower Saxony (Germany). Boosted regression trees were used to analyse the impact of different characteristic habitat types (e.g. vegetated, woody or open water zones), shoreline water depth and lake-level environmental variables on species-specific fish abundances. In contrast to earlier studies, lake-level environment and transect-level habitat type similarly influenced the abundances of differently sized fish species in the littoral zone of gravel pit lakes. The abundance of almost all fish species increased with lake productivity and extent of structured littoral habitats, mostly following non-linear relationships. Our work suggests that investments into the quality of littoral habitat, and not merely the control of nutrient inputs or other lake-level environmental factors, can promote abundance of most gravel pit lake fish species, in particular those who depend on the littoral zone for at least part of their life-cycle.

A tale from the middle Paleocene of Denmark: A tube-dwelling predator documented by the ichnofossil Lepidenteron mortenseni n. isp. and its predominant prey, Bobbitichthys n. gen. rosenkrantzi (Macroridae, Teleostei)

The ichnofossil Lepidenteron provides a unique taphonomic window into the life habits of a tube-dwelling predator, probably an eunicid polychaete, and its fish prey. Here we describe a new tube-like ichnofossil Lepidenteron mortenseni n. isp. from the Kerteminde Marl (100–150 m palaeo-water depth) from the Gundstrup gravel pit near Odense, Fyn, Denmark. 110 individual tubes were examined which contain fish remains, including a variety of disarticulated bones and otoliths, by far dominated by a single gadiform taxon referred herein to as Bobbitichthys n. gen. The isolated otoliths here associated with disarticulated gadiform bones have previously been described, from the time equivalent Lellinge Greensand exposed in the Copen-hagen area, as Hymenocephalus rosenkrantzi, a grenadier fish (family Macrouridae). The abundance of associated bones and otoliths in the examined tubes allowed us to reconstruct part of the cranial configuration of Bobbitichthys rosenkrantzi and to tentatively interpret it as a stem macrourid. Bobbitichthys rosenkrantzi represents the earliest grenadier known in the fossil record. Additional, although considerably less abundant, skeletal remains and otoliths have been tentatively referred to a long-fin bonefish (family Pterothrissidae, Pterothrissus? conchaeformis), a viviparous brotula (family Bythitidae, Bidenichthys? lapierrei), a conger eel (family Congridae, possibly belonging to Rhynchoconger angulosus), and another unidentified gadiform.

A Quarried Excavation Site : Late Bronze Age Relics Unearthed in a Gravel Pit near Muhi

East of the village of Muhi, in the direction of Nyékládháza, there are huge gravel pits, many of which have already been abandoned, flooded, and transformed into popular modern resorts. Recently, new gravel extraction sites have also been opened, and so a rescue excavation of the Muhi-III kavicsbánya (gravel pit) site took place in 2019. After months of excavation, the artifacts are still in the process of being cleaned and restored, and so until this work is complete, it is only possible to outline a brief overview of the important and remarkable finds. Features have been excavated from several periods (Middle Neolithic, Late Bronze Age, and Early Iron Age), but the most significant ones are those from the Late Bronze Age. These finds reveal information about a place of intensive human activity, a settlement on the border of different European cultural zones that participated in long-distance trade. These influences are reflected in varied elements of material culture. The large quantities of metal and ceramic finds brought to light in various conditions can be dated to the so-called pre-Gava period based on finds from the major features (urn graves, vessel hoards), and thus provide new information on the Late Bronze Age history of the Sajó-Hernád plain.

Szakony-Kavicsbánya cemetery from the age of the Hungarian conquest

In the spring of 1961, a graveyard with 7 graves from the age of the Hungarian conquest was found in a gravel pit near Szakony. The graves of 1 man, 2 women and 4 children were documented in the fully excavated cemetery. The nature and geographical location of the site have already attracted particular attention during the research, helping to determine the former extent of the settlement area. Biochemical research identified consanguineal relations between the deceased, thus research often identifies this site to date as a small-family cemetery. It was mainly the finds from horse burials that attracted attention in the material, and it is in this cemetery that the presence of metal-mounted harnesses used by men was first observed authentically. The observations regarding the female grave (no. 6) led to the first authentic reconstruction of a saddle decorated with silver plates too. The research also revealed the Carolingian origin of a harness ornament from grave 7, and almost exact Eastern European parallels of one of the rosette mounts. A new and interesting combination was the olive bead and the plate button from grave 6, examples of the former have only recently become known from Hungarian cemeteries previously thought to be devoid of finds in this respect. No less interesting is the question of the Eastern European parallels of harness mounts or parts of them, which do not exclude the possibility that they were made further east of the Carpathian Basin. But it cannot, of course, be ruled out that the similarities can be interpreted as traces of a system of contacts with the East that existed in the 10th century. Perhaps the former possibility cannot be dismissed either, together with the dating of the cemetery to the end of the 9th century and the early decades of the 10th century, as suggested by scientific dating. In the case of the deceased, the archaeogenetic analysis of the assessable samples refuted the existence of any kinship links, so it is certain that it was not the members of a small family based on consanguinity who were laid to rest in the Répce Valley sometime in the early 10th century.

Vibration Measurement of a Screening Machine

In this paper we use linear vibration approach to make a model of a horizontal vibration screen, which can be applied at gravel pit in order to perform separation operation of the wet gravel particles. The model can produce the natural frequencies of the system, which are useful in the adjustment of the angular velocity of the vibration exciter. A laser triangulation unit is well applicable to measure peak-to-peak amplitude of the working vibration screen. Comparison has been performed between the results of the simulation and the measurements.