This book contains 36 of the papers presented at the meetings covering the many aspects of oligochaete biology from ecological through evolutionary studies, divided into the following sections:

1. Systematics and Evolution
2. Taxonomy and Geographic Distribution
3. Distribution, Abundance and Habitat Types
4. Ultrastructure
5. Pollution Studies
6. Population Dynamics The volume highlights the single largest contribution of Soviet oligochaete biology presented in English since 1980. Nine of the 36 papers in this collection are written by authors from the former U.S.S.R.

Zusammenfassung
Proceedings of the 5th Oligochaete Symposium held in Tallinn, Estonia, 1991

Inhalt
I. Systematics and evolution.- Some characteristics of genetic variants of Tubifex tubifex (Müller, 1774) (Oligochaeta: Tubificidae) in laboratory cultures.- Morphology of some species of the genus Aulodrilus Bretscher.- A description of spermatozoan ultrastructure and some anatomical characters in Branchiobdella kozarovi Subchev, 1978 (Annelida: Clitellata), and review of the spermatozoan morphology within the genus.- II. Taxonomy and geographic distribution.- Oligochaete fauna of Lake Baikal.- A preliminary review of the taxonomic characters used for the systematics of the genus Trichodrilus Claparède (Oligochaeta, Lumbriculidae).- The enchytraeid fauna of North Africa.- Propappidae and aquatic Enchytraeidae (Oligochaeta) from the farthest southeast of Russia.- Oligochaetes (Naididae, Tubificidae, Enchytraeidae and Alluroididae) of Guyana, Peru and Ecuador.- Oligochaetes of the River Rhine. Preliminary records.- III. Distribution, abundance and habitat types.- Composition and distribution of the bottom oligochaete fauna of a north Italian eutrophic lake (Lake Ledro).- Habitat preferences and species associations of shallow-water marine Tubificidae (Oligochaeta) from the barrier reef ecosystems off Belize, Central America.- Communities of oligochaetes in mountain streams of Poland.- Oligochaeta in Spartina stems: the microdistribution of Enchytraeidae and Tubificidae in a salt marsh, Sapelo Island, USA.- Distribution of Oligochaeta in some lakes and pools of Bolivia.- Influence of small river conditions on the abundance of Tubificidae.- Aquatic Oligochaeta of the Dnieper-Bug estuary system.- On the distribution patterns and population dynamics of sublittoral and profundal oligochaeta fauna from Lake Banyoles (Catalonia, NE Spain).- Depth distribution of oligochaetesin Lake Baikal (Siberia Russia).- IV. Ultrastructure.- Ultrastructural and histochemical comparison in haplotaxids.- An ultrastructural overview of tubificid spermatozoa.- Body wall muscles in oligochaetes.- Comparative body wall musculature and muscle fiber ultrastructure in branchiobdellidans (Annelida: Clitellata), and their phylogenetic significance.- V. Pollution studies.- Response of tidal freshwater macrobenthos to sediment disturbance.- Oligochaetes and water pollution in two deep Norwegian lakes.- A field test of a sediment bioassay with the oligochaete worm Tubifex tubifex (Müller, 1774).- Lacustrine profundal meiobenthic oligochaetes as indicators of trophy and organic loading.- Oligochaete response to changes in water flow in the Dokka Delta, Lake Randsfjorden (Norway), caused by hydroelectric power development.- An experimental manipulation of oligochaete communities in mesocosms treated with chlorphyrifos or nutrient additions: multivariate analyses with Monte Carlo permutation tests.- VI. Population dynamics.- Quantitative observations on the population ecology of Branchiura sowerbyi (Oligochaeta, Tubificidae).- Biology of Limnodrilus claparedeanus Ratzel (Oligochaeta, Tubificidae) in the Tsimlyansk Reservoir.- Population dynamics of Potamothrix alatus paravanicus Poddubnaya & Pataridze (Tubificidae) in different areas of Laken Sevan.- Influence of environmental factors on the production of Potamothrix alatusparavenicus Poddubnaya & Pataridze (Tubificidae) in different areas of Lake Sevan.- Population dynamics and energy budget of Marionina southerni (Cernosvitov) (Enchytraeidae, Oligochaeta) in the shallow littoral of Lake Esrom, Denmark.- Population dynamics of Narapa bonettoi Righi and Varela, 1983 (Oligochaeta:Narapidae) from the main channel ofthe Middle Paraná River, Argentina.- Production of some oligochaete species in large Estonian lakes.- Observations on cohorts of Tubifex tubifex cultured at different food levels, using cellulose substrate.