Fossil cephalopods are frequently encrusted by epibionts; however, determining whether encrustation occurred prior to or post-mortem to the host, and whether the final environment of deposition corresponds to the habitat of encrustation is complex. The present paper describes cirripede epibionts, their calcareous bases and their attachment scars on 6 post-mortem shells of Nautilus macromphalus, collected from deep water off New Caledonia. The cirripedes have left both cemented calcareous bases of Hexelasma and scars associated with bioerosion and discoloration produced by verrucomorph barnacles. Live cirripedes included a Metaverruca recta, with articulated opercular plates and organic tissue (on a shell that had been exposed on the sea floor for at least 150 years), and specimens of Hexelasma velutinum, one of which was partly attached to an internal surface of a shell. The disposition of verrucomorphs indicates that most Nautilus shells were colonized post-mortem rather than during a floating stage. However, as cirripedes are known to have colonized living Nautilus, some Hexelasma, preserved only as calcareous eroded bases, may represent specimens that settled on a living Nautilus. The degree of bioerosion and discoloration induced by verrucomorph barnacles varies according to the surface preservation of Nautilus shells, with deeper and discolored traces preserved on old and degraded shells. Traces made by verrucomorphs described here are ellipsoidal and a new ichnotaxon, Anellusichnus ellipticus, is proposed to accommodate them. Importantly, verrucomorphs and other cirripede taxa with membranous bases that were attached to pristine shells may not leave any substantial scars, and, thus, will be difficult to detect in the fossil record.
- MeSH
- korýši klasifikace fyziologie MeSH
- Nautilus * MeSH
- skořápky zvířat * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Nová Kaledonie MeSH
- Tichý oceán MeSH
Infective nymphal stages of the family Sebekidae Sambon, 1922 are reported from four species of fish in Australian waters for the first time. Infected fish were collected from locations in Western Australia, the Northern Territory and north Queensland. The infective nymphs of Alofia merki Giglioli in Sambon, 1922 and Sebekia purdieae Riley, Spratt et Winch, 1990 are reported and described for the first time. The remaining specimens were identified as belonging to the genus Sebekia Sambon, 1922 based on the combination of buccal cadre shape, shape and size of hooks, and overall body size, but could not be attributed to any of the other species of Sebekia already reported due to missing required morphological features. DNA sequences of members of the family Sebekidae are presented for the first time. The lack of knowledge on the pentastome fauna of wild crocodiles, and any potential intermediate hosts, in northern Australia, is also outlined.
- MeSH
- aligátoři a krokodýli parazitologie MeSH
- druhová specificita MeSH
- korýši anatomie a histologie klasifikace genetika MeSH
- nymfa fyziologie MeSH
- ryby parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Austrálie MeSH
The WHAM-FTOX model quantifies the combined toxic effects of protons and metal cations towards aquatic organisms through the toxicity function (FTOX), a linear combination of the products of organism-bound cation and a toxic potency coefficient for each cation. We describe the application of the model to predict an observable ecological field variable, species richness of pelagic lake crustacean zooplankton, studied with respect to either acidification or the impacts of metals from smelters. The fitted results give toxic potencies increasing in the order H(+) < Al < Cu < Zn < Ni. In general, observed species richness is lower than predicted, but in some instances agreement is close, and is rarely higher than predictions. The model predicts recovery in agreement with observations for three regions, namely Sudbury (Canada), Bohemian Forest (Czech Republic) and a subset of lakes across Norway, but fails to predict observed recovery from acidification in Adirondack lakes (USA).
- MeSH
- chemické látky znečišťující vodu toxicita MeSH
- chemické modely * MeSH
- jezera chemie MeSH
- korýši klasifikace účinky léků růst a vývoj MeSH
- kovy toxicita MeSH
- monitorování životního prostředí metody MeSH
- protony MeSH
- zooplankton klasifikace účinky léků růst a vývoj MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Geografické názvy
- Česká republika MeSH
- Kanada MeSH
- Norsko MeSH
Fish parasitology has a long tradition in North America and numerous parasitologists have contributed considerably to the current knowledge of the diversity and biology of protistan and metazoan parasites of freshwater fishes. The Journal of Parasitology has been essential in disseminating this knowledge and remains a significant contributor to our understanding of fish parasites in North America as well as more broadly at the international level. However, with a few exceptions, the importance of fish parasites has decreased during the last decades, which is reflected in the considerable decline of funding and corresponding decrease of attention paid to these parasites in Canada and the United States of America. After the 'golden age' in the second half of the 20th Century, fish parasitology in Canada and the United States went in a new direction, driven by technology and a shift in priorities. In contrast, fish parasitology in Mexico has undergone rapid development since the early 1990s, partly due to extensive international collaboration and governmental funding. A critical review of the current data on the parasites of freshwater fishes in North America has revealed considerable gaps in the knowledge of their species composition, host specificity, life cycles, evolution, phylogeography, and relationships with their fish hosts. As to the key question, "Why so neglected?" this is probably because: (1) fish parasites are not in the forefront due to their lesser economic importance; (2) there is little funding for this kind of research, especially if a practical application is not immediately apparent; and (3) of shifting interests and a shortage of key personalities to train a new generation (they switched to marine habitats or other fields). Some of the opportunities for future research are outlined, such as climate change and cryptic species diversity. A significant problem challenging future research seems to be the loss of trained and experienced fish parasitologists. This has 2 major ramifications: the loss of expertise in identifying organisms that other biologists (e.g., ecologists, molecular biologists, evolutionists) work with, and an incomplete comprehension of ecosystem structure and function in the face of climate change, emerging diseases, and loss of biodiversity.
- MeSH
- Ciliophora klasifikace MeSH
- cizopasní červi klasifikace MeSH
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- Kinetoplastida klasifikace MeSH
- korýši klasifikace MeSH
- Microsporida klasifikace MeSH
- Myxozoa klasifikace MeSH
- nemoci ryb dějiny parazitologie MeSH
- opomíjené nemoci parazitologie veterinární MeSH
- parazitární nemoci u zvířat dějiny parazitologie MeSH
- parazitologie dějiny MeSH
- periodika jako téma dějiny MeSH
- pijavice klasifikace MeSH
- ryby MeSH
- sladká voda MeSH
- zvířata MeSH
- Check Tag
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- historické články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Geografické názvy
- Severní Amerika MeSH
- MeSH
- klasifikace MeSH
- korýši anatomie a histologie klasifikace MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Geografické názvy
- jižní Afrika MeSH
- MeSH
- korýši anatomie a histologie klasifikace MeSH
- ryby parazitologie MeSH
- Publikační typ
- srovnávací studie MeSH
- Geografické názvy
- Argentina MeSH
