Oligochaete fauna of Lake Baikal

Oligochaetes are one of the most abundant groups of invertebrates in Lake Baikal. They compose up to 70–90% of the biomass and numbers of zoobenthos and are distributed from the water edge to the maximum depth. There are 207 identified species and subspecies belonging to 44 genera and seven families, of which 160 species and 13 genera are endemic. Many are relict species. The main peculiarities of oligochaete fauna of Lake Baikal are: immiscibility of its ecologically different complexes (Palaearctic and Baikalian), its antiquity and heterogeneity, and intense radiation of the species.     

Rhododrilus sexpapillatus n.sp. (Oligochaeta: Megascolecidae) from New Zealand

Abstract

A new earthworm species belonging to the acanthodriline genus Rhododrilus is described from the North Island of New Zealand, elevating the generic total (excluding Australian forms) to 30 species. The new taxon forms part of the species-group with incomplete fusion of the male and prostatic terminalia. Its most closely related congener is the geographically proximate R. papaensis. Though exhibiting great heterogeneity, suggestive of polyphyly, the genus remains taxonomically convenient. It probably encompasses convergent forms, the ancestral affinities of which may never be ascertained.     

Properties of Gracilaria agars

Data are presented concerning an investigation into the diversity, abundance, production and respiration of the oligochaete fauna in the eutrophic, polymictic Lake Zbechy and in a melioration canal in the Wielkopolska Region, an area of intensive agriculture. It was found that in the canal the average biomass of oligochaetes was about four times higher than in the lake. Oligochaetes expend 1.1–4 times more energy in respiration than in tissue production. Species diversity and species number are positively correlated, while the correlation between diversity and abundance is negative.     

Ecology and importance of Oligochaeta in the biocenosis of zoobenthos in lakes of the National Park of the Lithuanian SSR

This paper aims to describe the ecology and determine the distribution of Oligochaeta according to sediment type, depth and other environmental factors in 21 lakes of the National Park of the Lithuanian SSR. Diagrams are included showing the distribution of the lakes according to the index of density and biomass of Oligochaeta in the trophic structure of biocenosis of the zoobenthos. Light is thrown on the problem of sediment composition as a significant factor in the distribution and development of aquatic Oligochaeta.     

The biology of Psammoryctides barbatus (Grube) in English chalk streams

The tubificid Psammoryctides barbatus is common in the sediments of English chalk streams. The species is primarily a spring and summer breeder with the most intense period of reproduction from April to June throughout its distribution in the river. Recruitment of juveniles takes place chiefly from June to August and most of the worms attain maturity in the following spring. In culture at 15 °C worms had attained 38 mm within 90 days of hatching and showed early signs of maturity. Growth rates and rates of cocoon production in culture are presented.     

Fluorescence and ultrastructural localization of aminergic neurons in the nerve cord of Eisenia foetida (Annelida—Oligochaeta)

Summary The aminergic nature of the CV neurons present in the genital segments of the nerve cord of Eisenia foetida is demonstrated by fluorescence microscopy and by the chromaffin reaction modified for electron microscopy.     

A comparison of two tubificid oligochaete species as candidates for sublethal bioassay tests relevant to subtropical and tropical regions

Two tubificid oligochaetes, Branchiura sowerbyi and Tubifex tubifex, were evaluated as potential test organisms for sediment bioassays. We attempt to reproduce the sediment bioassay proposed by Reynoldson et al. (1991) using his strain of Tubifex tubifex and his reference sediment and to compare this technique using Branchiura sowerbyi. This species was chosen because it is more common and dominant in tropical and subtropical environments than Tubifex tubifex. Data on survival and reproduction were obtained for both species, and growth estimates were obtained for B. sowerbyi. The sublethal bioassay with T. tubifex confirmed earlier estimates of a test duration of 4 weeks at 22.5 °C. B. sowerbyi cultures can produce usable estimates in 21 days at 30 °C.