Stratigraphy,facies and synsedimentary tectonics in the Jurassic Rosso Ammonitico Veronese (Altopiano di Asiago,NE Italy)

Summary The red, pelagic limestones of the Rosso Ammonitico Veronese (Upper Bajocian-Tithonian) of the Altopiano di Asiago area can be subdivided into eight facies. They differ from each other in structure (bedding style, presence and type of nodularity) and texture (nature of components, grain-vs mud-support, compactional features). Several discontinuities could be recognized, based on sedimentological or biostratigraphic evidence. In the context of a drowned platform, where sediments essentially consist of skeletal remains of both planktonic and benthic organism, the different facies are interpreted as reflecting a varying influence of currents on the winnowing of micrite and on triggering early cementation. Early cementation in turn, controlled the patterns of bioturbation and the response of sediments to later compaction and pressure-dissolution. At times, microbial mats, of unidentified nature, were important in trapping and binding sediment, giving rise to early lithified nodules and layers of stromatolitic aspect. The Rosso Ammonitico Veronese can be subdivided into three units: lower Rosso Ammonitico (RAI: Upper Bajocian-Lower Callovian), middle Rosso Ammonitico (RAM: Upper Callovian-Middle Oxfordian), and upper Rosso Ammonitico (RAS: Lower Kimmeridgian-Tithonian). Frequent ammonite moulds allow the precise dating of the base and top of each unit, and the documentation of facies heteropies and hiatusses in the more fossiliferous RAS. The lower unit (RAM) is massive and essentially nodular; the middle unit (RAM) is well bedded, non-nodular, and cherty; the upper unit (RAS) is richer in clay and typically nodular. The RAI and the RAS are present everywhere, though significant facies and thickness changes affect particularly the RAS; the RAM is much more variable, ranging from 0 to 10 metres. These variations, that may be gradual or abrupt, are inter-preted as the result of Middle-Late Callovian block-faulting which generated an irregular sea floor topography where the swells were more exposed to currents that continuously removed sediments, inducing long-lasting periods of nondeposition. Sediments preferentially accumulated in the adjacent lows. A confirmation of this hypothesis is provided by evidence of synsedimentary tectonics, described for the first time in the Rosso Ammonitico Veronese. Neptunian dykes, both vertical and horizontal, are developed at the top of the RAI and are filled with laminated sediments or collapse breccias. Glides of metre-size blocks and slumps are present at the top of the RAI and at the base of the RAM, respectively. Cm-thick layers of mud supported breccias are intercalated in the upper part of the RAI and within the RAM: they are interpreted as seismites. All these features document a tensional regime that generated fractures in more or less lithified sediments and failure along steep fault scarps or gently dipping slopes of tilted fault blocks. Recognition of this Callovian-Oxfordian tectonic activity shows that, after the Bajocian drowning, the Trento Plateau did not simply experience a uniform and general foundering: a small-scale block-faulting was still active and affected the pattern of facies distribution.     

Reproduction in the North Atlantic oceanic ichthyofauna and the relationship between fecundity and species' sizes

Synopsis The pelagic (589 spp.) and demersal (505 spp.) oceanic ichthyofaunas of the North Atlantic Basin have very different compositions at ordinal and family level. Yet the pattern of relationships between species' maximum size and maximum fecundity from data available (10% of the pelagic, 19% of the demersal species) was similar. A positive relationship between fecundity and weight was confirmed among most teleosts, but was not followed by the elasmobranchs represented. Species' reproductive styles are reviewed in ordinal groupings within a framework of the overall body size/fecundity distribution. Species size (maximum weight) spectra were synthesized for both pelagic and demersal assemblages to assess the allocation of potential reproductive effort throughout the North Atlantic oceanic ichthyofauna. The only available examples of species size spectra and biomass spectra from the pelagic and demersal ichthyofauna in this ocean basin imply geographic and bathymetric variation in overall reproductive effort among fishes whose fecundity is size dependent. Further implications concerning reproductive effort are discussed in the light of food availability.     

支序分类CLADISTICS在浮游多毛类眼蚕科ALCIOPIDAE系统演化研究中的应用

本论文运用支序分类学,借助于计算机技术,详细探讨了浮游多毛类眼蚕科(Alciopidae)九属的系统演化关系,并同前人的进化分类学和数值分类学研究结果进行了比较,对眼蚕科各属的演化途径提出了新的见解。     

Anti-egg predator behaviors of the small angelfish Centropyge ferrugatus (Pomacanthidae)

Synopsis Predation on eggs of the angelfish, Centropyge ferrugatus, was observed in the coral reefs of Sesoko Island, Okinawa, Japan. This angelfish released pelagic eggs in pairs at sunset after slow ascents. Of 99 matings of this angelfish, an omnivorous damselfish Amblyglyphidodon curacao approached in 25, and fed on the released eggs in eight cases. The spawning angelfish never attacked the egg-predators. Pairs of this angelfish avoided the egg-predators by delaying mating for several minutes during courtships, and by frequent changes of spawning sites. Of the 25 matings targeted by the egg-predators, the angelfish successfully avoided predation in 17 cases. Eight matings were failures mainly due to lack of any attempt to elude the predator, suggesting that the delayed matings on multiple spawning sites are effective anti-egg predator behaviors.     

Field experiments on the optical orientation of pelagic rotifers

Avoidance of shore by pelagic rotifers is considered to be the result of an optical orientation. Field experiments show that the spatial light distribution in the shore region determines the preferred direction of migration. The behaviour of Eudiaptomus gracilis was tested in comparison to that of rotifers.This publication is dedicated to Pater Dr. Josef Donner on the occasion of his 70th birthday     

Development of a Real-Time PCR assay for quantitative assessment of uncultured freshwater zoosporic fungi

Recently, molecular environmental surveys of the eukaryotic microbial community in lakes have revealed a high diversity of sequences belonging to uncultured zoosporic fungi. Although they are known as saprobes and algal parasites in freshwater systems, zoosporic fungi have been neglected in microbial food web studies. Recently, it has been suggested that zoosporic fungi, via the consumption of their zoospores by zooplankters, could transfer energy from large inedible algae and particulate organic material to higher trophic levels. However, because of their small size and their lack of distinctive morphological features, traditional microscopy does not allow the detection of fungal zoospores in the field. Hence, quantitative data on fungal zoospores in natural environments is missing. We have developed a quantitative PCR (qPCR) assay for the quantification of fungal zoospores in lakes. Specific primers were designed and qPCR conditions were optimized using a range of target and non-target plasmids obtained from previous freshwater environmental 18S rDNA surveys. When optimal DNA extraction protocol and qPCR conditions were applied, the qPCR assay developed in this study demonstrated high specificity and sensitivity, with as low as 100 18S rDNA copies per reaction detected. Although the present work focuses on the design and optimization of a new qPCR assay, its application to natural samples indicated that qPCR offers a promising tool for quantitative assessment of fungal zoospores in natural environments. We conclude that this will contribute to a better understanding of the ecological significance of zoosporic fungi in microbial food webs of pelagic ecosystems.     

Space-irrelevant scaling law for fish school sizes

Universal scaling in the power-law size distribution of pelagic fish schools is established. The power-law exponent of size distributions is extracted through the data collapse. The distribution depends on the school size only through the ratio of the size to the expected size of the schools an arbitrary individual engages in. This expected size is linear in the ratio of the spatial population density of fish to the breakup rate of school. By means of extensive numerical simulations, it is verified that the law is completely independent of the dimension of the space in which the fish move. Besides the scaling analysis on school size distributions, the integrity of schools over extended periods of time is discussed.     

Tracing carbon flow in an arctic marine food web using fatty acid-stable isotope analysis

Global warming and the loss of sea ice threaten to alter patterns of productivity in arctic marine ecosystems because of a likely decline in primary productivity by sea ice algae. Estimates of the contribution of ice algae to total primary production range widely, from just 3 to >50%, and the importance of ice algae to higher trophic levels remains unknown. To help answer this question, we investigated a novel approach to food web studies by combining the two established methods of stable isotope analysis and fatty acid (FA) analysis--we determined the C isotopic composition of individual diatom FA and traced these biomarkers in consumers. Samples were collected near Barrow, Alaska and included ice algae, pelagic phytoplankton, zooplankton, fish, seabirds, pinnipeds and cetaceans. Ice algae and pelagic phytoplankton had distinctive overall FA signatures and clear differences in delta(13)C for two specific diatom FA biomarkers: 16:4n-1 (-24.0+/-2.4 and -30.7+/-0.8 per thousand, respectively) and 20:5n-3 (-18.3+/-2.0 and -26.9+/-0.7 per thousand, respectively). Nearly all delta(13)C values of these two FA in consumers fell between the two stable isotopic end members. A mass balance equation indicated that FA material derived from ice algae, compared to pelagic diatoms, averaged 71% (44-107%) in consumers based on delta(13)C values of 16:4n-1, but only 24% (0-61%) based on 20:5n-3. Our estimates derived from 16:4n-1, which is produced only by diatoms, probably best represented the contribution of ice algae relative to pelagic diatoms. However, many types of algae produce 20:5n-3, so the lower value derived from it likely represented a more realistic estimate of the proportion of ice algae material relative to all other types of phytoplankton. These preliminary results demonstrate the potential value of compound-specific isotope analysis of marine lipids to trace C flow through marine food webs and provide a foundation for future work.     

Carbohydrate synthesis by two Navicula strains isolated from benthic and pelagic mucilages in the Tyrrhenian Sea (Tuscan Archipelago)

Two exopolysaccharide (EPS)-producing strains of the diatom Navicula, were isolated from benthic and pelagic mucilaginous aggregates sampled in the Tyrrhenian Sea and cultured under laboratory conditions. The amount of carbohydrate formed over the growth period and on a per cell basis was quite similar. However, the benthic strain showed a preferential synthesis of the bound (i.e., cellular and capsular) carbohydrate fraction, whereas the pelagic strain preferentially synthesised soluble, polymeric carbohydrates. The polysaccharides released into the medium by the two strains showed the same qualitative monosaccharidic composition, being constituted by two acidic and six neutral sugars. It is suggested that the difference between the benthic and the pelagic strain in the synthesis of bound or soluble carbohydrates may be related to the different role of these compounds in the particular habitats of the strains.     

Cutaneous and diphtheritic avian poxvirus infection in a nestling Southern Giant Petrel (Macronectes giganteus) from Antarctica

The Southern giant petrel (Macronectes giganteus) is declining over much of its range and currently is listed as vulnerable to extinction by the International Union for the Conservation of Nature (IUCN). Island-specific breeding colonies near Palmer Station, Antarctica, have been monitored for over 30 years, and because this population continues to increase, it is critically important to conservation. In austral summer 2004, six diseased giant petrel chicks were observed in four of these colonies. Diseased chicks were 6–9 weeks old and had multiple proliferative nodules on their bills and skin. One severely affected chick was found dead on the nest and was salvaged for necropsy. Histopathological examination of nodules from the dead chick revealed epithelial cell hyperplasia and hypertrophy with numerous eosinophilic intracytoplasmic inclusions (Böllinger bodies). A poxvirus was isolated from multiple nodules. Poxviral infection has not been reported in this species, and the reason for its emergence and its potential impact on the population are not yet known.