149 research outputs found
Kingdom Animalia, phylum Gastrotricha (hairy-bellied worms)
The New Zealand Gastrotricha fauna is effectively unknown (Table 10.1; Fig. 10.1). The total number of recorded taxa from the Aotearoa New Zealand region is four genera and four undescribed species from the order Macrodasyida, and one undescribed specimen from the order Chaetonotida (fam., genus et sp. indet.; Table 10.1). In addition, there are over 330 specimens of unidentified Gastrotricha collected from New Zealand. The discovery rate, rate of description, and increase in our knowledge of gastrotrich diversity for New Zealand waters has remained unchanged during the last two decades (since Sterrer 2009). A checklist of New Zealand Gastrotricha is provided
Reproductive system of the genus Crasiella (Gastrotricha, Macrodasyida)
Crasiella diplura from Sweden and Crasiella sp. from Italy were studied alive and with transmission electron microscopy (TEM). The two species are simultaneous hermaphrodites and share the same reproductive system lay-out: paired ovaries extend along the posterior part of the intestine and join mid-dorsally, while bilateral,club-shaped testes lie at the sides of the anterior gut, extending as deferentia that fuse on the mid-ventral plane and open into a single pore; gametes mature in a caudocephalicand centripetal direction. The bulky, sac-like, frontal organ is lined by a simple epithelium and lies dorsolaterally to the intestine, on the left side of the body.The spindle-shaped caudal organ is musculo-glandular and is located ventrolaterally to the gut on the right side. It is characterized by the presence of a roughly Y-shapedinternal channel that opens into two pores close to each other, which function for the intake and outlet of the (auto)sperm, respectively. The spermatozoa, which arepeculiar and similar in the two species, are characterized by a long and complex acrosome consisting of four ultrastructurally distinct regions, three of which findequivalence in other gastrotrich species. The flagellum lacks a striated cylinder. Anatomy and ultrastructure enable us to hypothesize a modality of sperm transfer in Crasiellathat is similar to that observed in Macrodasys
Steaming effects on selected wood properties of Turkey oak by spectral analysis
Turkey oak (Quercus cerris L.) is characterized by some technological and aesthetical factors limiting its market value from its great potential. In this study, the effect of direct and indirect steaming on reduction in equilibrium moisture content (EMC) and colour variations was evaluated using a hyperspectral radiometer.
Steaming treatments were carried out at 80C for 48 h, and 120C for 18 and 24 h, showing a reduction in EMC in the order of 8.1, 28.5 and 13.5, respectively, as well as very significant lightness (L*) and hue (h) modifications in comparison with untreated specimens. The spectral signature analysis confirmed that hydrothermal treatments modify wood sensibility to the light source in the entire spectrum range.
The study supports the validity of hydrothermal treatments for improving technological and aesthetical properties of Turkey oak
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Faunistics and zoogeographical overview of the Mediterranean and Black Sea marine Gastrotricha.
The paper provides an updated overview of the knowledge regarding the marine gastrotrich fauna of 10 Mediterranean and 2 Black Sea countries. Taxonomic account and species distribution come from published records, including electronically disseminated information, as well as original data from 18 localities (16 western and 2 levantine), investigated by the authors between 1990 and 2002. Since the description of the first marine Mediterranean gastrotrich, Emydasys agaso Claparede, 1867, discovered in the Gulf of Naples (Italy), 273 additional species, from 417 locations have been recorded in the basin so far. Of the gastrotrichs found, 143 species, in 24 genera and 6 families, belong to the order Macrodasyida and 131 species, in 11 genera and 3 families, belong to the order Chaetonotida; these statistics include several species as of yet not described. The number of species per location is variable, ranging from 1-37, with a global mean of 8.04 \uf0b1 6.69 spp/location. Egypt and Israel show mean values well above the average, with 12.8 and 10.8 spp/loc. respectively, whereas mean values for Algeria, Tunisia, Bulgaria, Croatia, and France are below average (1- 5.43 spp /location); data for Cyprus, Greece, Romania and Italy are within the average value. Acanthodasys aculeatus, recorded in 28% of the investigated location is the most frequently found macrodasyidan; Halichaetonotus aculifer, also recorded in 28% of the investigated localities, is the most common chaetonotidan whereas. Data analysis indicated substantial differences among countries, regarding sampling effort and, consequently, faunistic knowledge. In comparison with the generally good information concerning the Italian fauna (177 species from 246 localities), gastrotrichs from other Mediterranean nations are much less known; along with Italy, only few other Nations have been investigated to a sufficient extent (i.e., Greece: 44 sampled localities, 77 recorded species; France: 37 L, 70 spp; Egypt: 28 L, 81 spp; Israel: 15 L, 55 spp; Cyprus: 9 L, 41 spp), whereas investigation carried out in several other countries can be considered, to a variable degree, incomplete (i.e., Algeria: 16 investigated localities and 11 species found; Romania: 7 L, 30 spp; Tunisia: 5 L, 2 spp; Bulgaria: 3 L, 11 spp; Croatia: 1 L, 12 spp, Spain: 1 L, 3 sp, Malta; 2L, 2 spp.), or nil (e.g., Morocco, Libya, Turkey, Albania). All marine gastrotrich families and most marine genera have representatives in the Mediterranean fauna, notable absences regard the genera Desmodasys, Dinodasys, Planodasys, Prostobuccantia and perhaps Pseudoturbanella; on the other hand representatives of two genera, Emydasys and Dendropodola, are unknown elsewhere in the world except the western Mediterranean. At species level, about 140 taxa have so far been found only in the Mediterranean area, whereas the remainder have some north-Atlantic connections, including several considered as regional cosmopolitans (i.e., reported from at least two Oceans). Within the Mediterranean, the species geographic distribution does not appear to be homogeneous, with several taxa restricted to either the western or to the levantine basin; yet, Italy, Egypt and Israel show the highest numbers of endemic species, 70, 24 and 14 respectively, whereas only one species seems restricted to the Black Sea. A cluster analysis using the Bray-Curtis presence-absence similarity value to examine the relationship between 11 geographic areas, shows a clear separation between the Black Sea and the Mediterranean regions and within this, the Algerian-Tunisian region is separated from and the remaining 9 areas. The latter appear arranged in two main clusters, one including the southern Levantine regions (i.e., Egypt, Israel and Cyprus), the other containing regions of the north-western basin, the Adriatic sea and the two Greek sub-regions. In this cluster, the region comprising coastal France and Formentera (Spain) appears separated from the one containing, arranged into two distinct subsets, the Italian and the Greek areas. However, due to the paucity of information, data from key-areas is urged to confirm or disprove our current perception about numbers and distribution of gastrotrich taxa within the Mediterranean and the Black Sea
Metazoans of redoxcline sediments in Mediterranean deep-sea hypersaline anoxic basins
Background: The deep-sea hypersaline anoxic basins (DHABs) of the Mediterranean (water depth similar to 3500 m) are some of the most extreme oceanic habitats known. Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB haloclines and brines, loriciferans are the only metazoan reported to inhabit the anoxic DHAB brines. Our goal was to further investigate metazoan communities in DHAB haloclines and brines.
Results: We report observations from sediments of three DHAB (Urania, Discovery, L'Atalante) haloclines, comparing these to observations from sediments underlying normoxic waters of typical Mediterranean salinity. Due to technical difficulties, sampling of the brines was not possible. Morphotype analysis indicates nematodes are the most abundant taxon; crustaceans, loriciferans and bryozoans were also noted. Among nematodes, Daptonema was the most abundant genus; three morphotypes were noted with a degree of endemicity. The majority of rRNA sequences were from planktonic taxa, suggesting that at least some individual metazoans were preserved and inactive. Nematode abundance data, in some cases determined from direct counts of sediments incubated in situ with CellTracker (TM) Green, was patchy but generally indicates the highest abundances in either normoxic control samples or in upper halocline samples; nematodes were absent or very rare in lower halocline samples. Ultrastructural analysis indicates the nematodes in L'Atalante normoxic control sediments were fit, while specimens from L'Atalante upper halocline were healthy or had only recently died and those from the lower halocline had no identifiable organelles. Loriciferans, which were only rarely encountered, were found in both normoxic control samples as well as in Discovery and L'Atalante haloclines. It is not clear how a metazoan taxon could remain viable under this wide range of conditions.
Conclusions: We document a community of living nematodes in normoxic, normal saline deep-sea Mediterranean sediments and in the upper halocline portions of the DHABs. Occurrences of nematodes in mid-halocline and lower halocline samples did not provide compelling evidence of a living community in those zones. The possibility of a viable metazoan community in brines of DHABs is not supported by our data at this time
Significant occurrence of Musellifer profundus Vivier, 1974 (Gastrotricha, Chaetonotida) in the Black Sea
Specimens of the gastrotrich genus Musellifer are recorded for the first time from the Black Sea. These specimens, identified as M. profundus Vivier, 1974, were found in sediment samples collected at various depths (22−135 m) and from waters characterized by low salinity (17.3−18.62‰) and varying levels of oxygen (2.43−299.59 μM). Three specimens were found from the Istanbul Strait (Bosphorus) outlet area of the Black Sea (Turkey) and 2 were found along the southern and southeastern shelf of the Crimean Peninsula (Russia), from the Yalta Gulf and the Feodosiya Gulf.&nbsp
Stress-driven AlN cantilever-based flow sensor for fish lateral line system
In this work, we report on the fabrication and characterization of stress-driven aluminum nitride (AlN) cantilevers to be applied as flow sensor for fish lateral line system. The fabricated structures exploit a multilayered cantilever AlN/molybdenum (Mo) and a Nichrome 80/20 alloy as piezoresistor. Cantilever arrays are realized by using conventional micromachining techniques involving optical lithography and etching processes. The fabrication of the piezoresistive cantilevers is reported and the operation of the cantilever as flow sensor has been investigated by electrical measurement under nitrogen flowing condition showing a sensitivity to directionality and to low value applied forces
First records of Gastrotricha from South Africa, with description of a new species of Halichaetonotus (Chaetonotida, Chaetonotidae)
During a survey of the biota of the St. Lucia Estuary in the iSimangaliso Wetland Park, South Africa, a number of Gastrotricha were found among samples of meiofauna. Fresh, marine sediment yielded several specimens belonging to a total of seven species. Of these, two are already known from other regions (i.e., Dactylopodola australiensis and Heteroxenotrichula squamosa), one is described as new to science (Halichaetonotussanctaeluciae sp. n.), while the remaining four (Pseudostomella sp., Halichaetonotus sp.1, Halichaetonotus sp. 2, Xenotrichula sp.) require further collections and analysis, in order to establish the extent of their affiliation to species already described. General appearance, shape of hydrofoil scale and the occurrenceof three long spines on the dorsal side make the new species most closely related to H. australis and H. marivagus. The key differences from these taxa and between Halichaetonotus sanctaeluciae sp. n. and H. aculifer are discussed
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