Ralph O. Brinkhurst

Aquatic Oligochaete Biology

Taxonomic Studies.- Specific and Generic Criteria in Freshwater Oligochaeta, With Special Emphasis on the Naididae.- Specific and Generic Criteria in Marine Oligochaeta, With Special Emphasis on Tubificidae.- Polychaete Sibling Species.- Ecophenotypic Variation in Setae of Naididae (Oligochaeta).- On the Question of Hybridization and Variation in the Oligochaete Genus Limnodrilus.- Zoogeographic Studies.- Distribution of Aquatic Oligochaetes.- The Aquatic Oligochaeta of Argentina: Current Status of Knowledge.- The Aquatic Oligochaeta of St. Lawrence Great Lakes Region.- Aquatic Oligochaeta of Southern England.- Life History and Production.- Life Cycles of Mass Species of Tubificidae (Oligochaeta).- Population Dynamics of Tubifex tubifex, Studied by Means of a New Model.- Production Biology of the Tubificidae (Oligochaeta).- The production biology of Terrestrial Enchytraeidae (Oligochaeta).- Ecological Studies.- Ecological Studies of Aquatic Oligochaetes in the USSR.- Aquatic Oligochaeta of the Rhone-Alpes Area: Current Research Priorities..- Affects of Tubificid Oligochaetes on Physical and Chemical Properties of Lake Erie Sediments.- Ecology of Freshwater and Estuarine Tubificidae (Oligochaeta).- The Ecology of Tubificids in the Thames Estuary with Particular Reference to Tubifex costatus (Claparede).- Seasonal Movements of Subtidal Benthic Communities in the Fraser River Estuary, British Columbia (Abstract)..- Tolerance and Preference Reactions of Marine Oligochaeta in Relation to Their Distribution.- Oligochaeta in Relation to Human Activity.- Oligochaeta Community Structure and Function in Agricultural Landscapes.- Oligochaete Communities in Pollution Biology: The European: Situation With Special Reference to Lakes in Scandinavia.- Structure of Tubificid and Lumbriculid Worm Communities, and Three Indices of Trophy Based Upon These Communities, as Descriptors of Eutrophication Level of Lake Geneva (Switzerland).- Pollution Biology - the North American Experience.- Heavy Metal Studies With Oligochaetes.- The Relationship of Saprobial Conditions to Massive Populations of Tubificids.- Postscript.- Participants.- Systematic Index.

Evolutionary relationships within the clitellata

Abstract The results from published cladistic analyses of various oligochaete taxa suggest that the Haplotaxidase is a paraphyletic taxon once Metataxis is transfered to the Lumbricina and Tiguassu to the Tiguassidae. The Branchiobdellida and Lumbriculidae appear to have shared a common ancestor in which two male ducts enter each strium. The leeches show no obvious sign of being related to the Lumbriculidae, and the significance of Acanthobdella may be overrated. The Naididae and Tubificidae seem to be more closely related than other families, and these, together with the Lumbriculidae, Dorydrilidae and Branchiobdellida, probably constitute a monophyly defined by the possession of atria with prostates. The Phreodrilidae and Enchytraeidae occupy the middle of the cladogram below these five taxa but above the Haplotaxidae and the presumed stem form of the Lumbricina. A number of smaller families (Capilloventridae, Randiellidae, Opistocystidae and others) cannot be placed with any confidence.

Lethal and sublethal tolerances of aquatic oligochaetes with reference to their use as a biotic index of pollution

A series of recent studies have been completed by the authors involving: 1) determining the lethal tolerances of 12 oligochaete species classified (from ecological studies) as tolerant, moderately tolerant and intolerant to selected chemical toxicants and environmental factors under defined bioassay conditions with and without sediment; 2) determining lethal tolerances of candidate species to toxicants in combination with a range of abiotic factors; 3) measuring respiratory stress imposed by exposure to individual and combined sublethal concentrations of toxicants and environmental factors; and, 4) determining differences in lethal tolerance and respiratory stress between individual and mixed species. Surprisingly few previous studies have been done in this area considering the importance of oligochaetes as field pollution indicators. The results of the above major studies coupled with histopathological work are reviewed. Data from these studies substantiate the present use of oligochaete species assemblages as indicators of organic pollution and suggest their use in the laboratory for toxicant screening tests. The range of responses of different oligochaete species to individual and combined stress is complex, particularly in mixed species, which provides useful indications of specific stress factors. The application of these experimental laboratory studies to field situations is described.

Hair today, gone tomorrow: induced chaetal changes in tubificid oligochaetes

Laboratory experiments were conducted to determine the extent of chaetal variation in the tubificids Tubifex tubifex and Ilyodrilus frantzi and the naidids Specaria fraseri and Nais communis under varying environmental conditions. Univariate exposures were carried out using different levels of pH, salinity, water hardness and mercury. We were not able to induce chaetal changes in the two naidids tested. However, we were able to reduce the hairs and pectinations of T. tubifex with exposure to pH, salinity and to hard water such that the bergi form was produced. Prolonged exposure to low or high pH resulted in the total loss of hairs and pectinates such that the blanchardi form was produced. We were able to eliminate the hairs and pectinates of I. frantzi (capillatus) in soft, freshwater exposures such that the bifidus form of I. frantzi was produced. Conversely, in hard or saline water we were able to induce formation of hairs and pectinates on the bifidus form such that the capillatus form was produced. These changes occurred at time intervals ranging from a few days to two months.

Did the lumbriculids provide the ancestors of the branchiobdellidans, acanthobdellidans and leeches?

Revision of the literature concerning Agriodrilus (Oligochaeta, Lumbriculidae) and Acanthobdella (Acanthobdellida), both supposedly intermediate links in the traditional single line of evolution between lumbriculids, branchiobdellidans, and leeches, supports the alternative hypothesis of an independent origin of most if not all of these groups. Discovery of Phagodrilus, a lumbriculid that is clearly convergent with Agriodrilus in terms of the pharynx, lends further support to this concept. No decision as to the rankings of the various taxa can be made until new material of Acanthobdella is examined and all variable characters are used to determine synapomorphic character states and monophyletic groupings within this complex.

A comparison of phenetic and phylogenetic methods applied to the systematics of Oligochaeta

A comparative study of naidid subfamilies shows that a combination of ordination, Jaccard/Average Linkage cluster analysis and Wagner parsimony provides a useful basis for a rational phylogeny but that this does not differ markedly from the original proposed by Sperber nearly four decades ago. Hennig rules, modified by Wiley, permit a preliminary phylogeny and classification of the Annelida to be made by hand. An error in earlier versions suggested that the Dorydrilidae lacked prostate glands, and this is corrected.

The development and application of analytical methods in benthic marine infaunal studies

Publisher Summary The purpose of this chapter is to examine the development of practical analytical approaches that have traditionally been applied to benthic soft-bottom macrofaunal (particularly marine) studies. Some commonly applied methods and topics are covered in more detail than others, especially if they are considered to be pivotal in the development of benthic analytical studies. Mensurative studies involve random sampling of the organisms (and related factors) from different stations, selected according to some reasonable survey pattern based on the objectives of the study. The primary aim of all methods discussed here continues to be the simplification of complex patterns occurring in benthic faunal assemblages, such that interpretation and comparison is possible. The key to further progress in this field is to develop sampling and analytical techniques in concert. This presupposes that research aims and study hypotheses can be more clearly stated in benthic studies than has often been the case in the past.

Lumbriculids, branchiobdellidans and leeches: an overview of recent progress in phylogenetic research on clitellates

The debates about the relationship among clitellate taxa at research conferences on aquatic oligochaetes have provided two alternative hypotheses. While both involve cladistic analyses, the differences focus on questions of homology. A single unique synapomorphy supports a taxon consisting of Branchiobdellida plus Lumbriculidae. Muscle ultrastructure provides a potential autapomophy for Lumbriculidae within the clade, while Branchiobdellida has many autapomophies. Some proposed synapomorphies for a Branchiobdellida plus Hirudinea grouping (jaws, oral sucker) are not based on homologous structures. Others (loss of chaetae, median male pore) are not unique, or are based on potentially convergent characters. Initial molecular analyses support a Branchiobdellida - Hirudinea grouping. A preliminary manually drawn cladogram based on re-evaluated characters supports Lumbriculidae, Branchiobdellida, Acanthobdella and Euhirudinea as a monophyletic taxon. Observations on sperm ultrastructure support this hypothesis. If substantiated, a very considerable change in nomenclature will result. However, before any nomenclatural changes are proposed, a resolution of the apparently paraphyletic Oligochaeta is necessary.

Comments on the evolution of the Annelida

The structure of the male ducts and their relative positions are significant indicators of the fact that the Lumbriculidae do not represent the stem forms of the Oligochaeta, confirming the recently expressed opinion of Hrabě (1983). However, the same arguments provide the basis for the separation of Dorydrilus in the family Dorydrilidae.

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.