Notes on inland water molluscs from Egypt (Mollusca: Gastropoda,Bivalvia)

Abstract

A report on two new collections of fresh- and brackish water molluscs in Egypt is filling gaps in the generally known distribution pattern. The recent status of the mollusc fauna of Birket Qarun (Fayum), changed by introduction of marine species into the brackish water lake, is documented.     

NEWS

ABSTRACT

Australian fur seals Arctocephalus pusillus doriferus are colonial breeding animals forming dense social groups during the breeding season. During this time, males establish and defend territories through physical conflicts, stereotyped posturing and vocalisations. While vocalisations are suggested to play an important role in male recognition systems, it has received little attention. Recordings of nine adult male Australian fur seals were made during the 2000 and 2001 breeding seasons at Kanowna Island (39° 10′S, 146° 18′ E), Bass Strait, Australia. The in-air bark vocalisations of territory-holding males were used to characterise the Bark Call and to determine whether males produce individually distinct calls, which could be used as a basis for vocal recognition. Seventeen frequency and temporal variables were measured from a total of 162 barks from nine individual males. The Bark Series was more reliably classified (83%) to the correct caller compared to the Bark Unit. This was assigned with less certainty (68%), although the classification was still relatively high. Findings from this study indicate that there is sufficient stereotypy within individual calls, and sufficient variation between them, to enable vocal recognition in male Australian fur seals.     

Description of Conticribra tricircularis,a new genus and species of Thalassiosirales,with a discussion on its relationship to other continuous cribra species of Thalassiosira Cleve (Bacillariophyta) and its freshwater origin

A new diatom genus Conticribra is erected to accommodate C. tricircularis, described from a freshwater Pliocene deposit in Trout Creek, Oregon (USA). The genus accommodates species possessing: (i) loculate areolae with (semi-) continuous cribra; (ii) non-plicated valve face; (iii) rimoportula located on the valve mantle, replacing a fultoportula. Conticribra tricircularis has no valve face fultoportulae and can easily be distinguished by its marginal fultoportulae with four satellite pores arranged in three rings. Three species are transferred to the new genus from Thalassiosira sensu lato. Using evidence from the fossil record and recent molecular data, a hypothesis concerning the freshwater origin of Conticribra is discussed.     

FRESHWATER FISH OF THE ADDO ELEPHANT NATIONAL PARK

Summary

This study aimed to determine the distribution and relative abundance of freshwater fish in the Addo Elephant National Park. A total of 1578 fish specimens of 12 species were collected during surveys carried out in the Sundays River and four tributaries during 1996 and 1997. The redfin minnow Pseudobarbus afer comprised 81.6% of the total catch. Length frequency analysis of P. afer populations indicated recent successful recruitment in several rivers. Differences between rivers in the concentrations of dissolved and suspended solids and pH are possible reasons for different species complements. These surveys show the distribution of P. afer and Barbus aeneus in the Eastern Cape Province to be wider than previously reported. Management action is required to minimise opportunities for further establishment and spread of alien and translocated fish species and to conserve indigenous fish assemblages within the Park.     

PRELIMINARY RESULTS ON THE UPTAKE AND RELEASE OF 32P BY POTAMOGETON PECTINATUS

SUMMARY

The absorption and release of ³²PO₄, by Potamogeton pectinatus L during winter was investigated using a partitioned container in which the roots were separated from the stems and leaves. ³²PO₄ is absorbed by the roots as well as the stems and leaves under both light and dark conditions and transported to all parts of the plant. Transport rates (μg P plant^?1 24 hr^?1) show that more phosphorus is released by the roots than by the stems and leaves, indicating a nett movement of phosphorus from the surrounding water to the substrate. Foliar absorption of ³²P exceeds root absorption under both light and dark conditions.     

中国淡水甲藻两个新记录属

我国此前关于光薄甲藻Glenodinium gymnodinium Penard在西藏那错湖的记录是基于错误的鉴定, 作者在相差显微镜下对标本进行了重新检查, 发现此甲藻的细胞壁由多数甲片构成, 甲片大小相似, 多为六角形, 应属于网甲藻属Woloszynskia Thompson的微小网甲藻W. tenuissima (Lauterborn) Thompson。中型四角甲藻Tetradinium intermedium Geitler采于武汉的一小池塘, 附着于一鞘藻属Oedogonium植物的丝状体上, 属于甲藻门中的不运动种类, 营养时期不能运动。两个属种均为中国新记录。