Systems and organismal aspects of phosphorus remineralization

During a six-month study at Lake George, N.Y., zooplankton contributed an average of 19.4% of the phosphate required for algal photosynthesis. Values ranged from 44.1% prior to the unimodal phytoplankton pulse to 4.6% during the phytoplankton bloom. Copepods accounted for a large percentage (21–68%) of the SRP recycled during the growing season examined, whereas, the cladocera provided only a small percentage of remineralization (6.9%).Contribution No. 315 from the Eastern Deciduous Forest Biome, U. .-IBP, Research supported by the Eastern Diciduous Forest Biome U.S.-IBP, funded by the National Science Foundation under interagency agreement AG-199. DEB 76-00761 with the U.S. Department of Energy — Oak Ridge National Laboratory.     

Arrested development and the histotropic phase of Ascaridia galli in the chicken

Studies on 300 worm-free chickens infected with Ascaridia galli indicated that the histotropic phase is a normal part of the life cycle and that it involves both second- and third-stage larvae. The duration of the histotropic phase was dose-dependent. At low dose rates (50 eggs) it occurred from days 3 to 16 and was terminated abruptly by the third ecdysis. At high dose rates (2000 eggs) it was prolonged until at least day 54, because third-stage larvae became arrested in their development and the third ecdysis was delayed. Arrested development of Ascaridia galli was significantly suppressed following treatment of birds with cyclophosphamide, but expulsion of worms was not prevented. This result suggests the involvement of host antibodies in the induction of the arrested state.     

An early Miocene deep‐water decapod crustacean faunule from the Vienna Basin (Western Carpathians,Slovakia)

Abstract: A decapod crustacean faunule from the lower Miocene (upper Burdigalian, ‘Karpatian’) of the Slovakian part of the Vienna Basin comprise five new species: Callianopsis marianae (Ctenochelidae), Crosniera schweitzerae (Thomassiniidae), Agononida cerovensis and Munidopsis lieskovensis (both Galatheidae) plus Mursia harnicari (Calappidae). The new species of Callianopsis is the first undoubted member of the genus to be recorded from Europe; it is based on sexually dimorphic major and minor chelae as well as on portions of carapace and abdomen. Crosniera schweitzerae sp. nov. and Agononida cerovensis sp. nov. constitute the first fossil members of these genera. Additional material of an enigmatic crab, Styrioplax exiguus, and a re‐examination of the type material, confirms assignment of that genus to the subfamily Rhizopinae (family Pilumnidae). Palaeoecological data suggest that deposition of the levels (Lak?árska Nová Ves Formation) from which these taxa were collected took place under generally low‐energy, deep‐water conditions that were conducive to the preservation of delicate structures. Palaeobiogeographical affinities of the described taxa suggest a trans‐Atlantic migration during the early Miocene.