Progress in cohort cultures of aquatic Oligochaeta

Genetic variants of the oligochaete Tubifex tubifex were identified with enzyme electrophoresis and subsequently reared in laboratory cultures. Three types are abundant in field populations. Individuals that show homozygotic bands of glucosephosphate-isomerase (GPI) 22 together with isocitratedehydrogenase (IDH) 35 were labeled Type A. Type B is characterized by GPI 23 together with IDH 11 and Type C is characterized by GPI 11 with either IDH 34 or IDH 33. Initial results on freshweights of adults and cocoon production revealed differences between the two main types, A and B. In the same period, Type B reached higher weights and produced five times as many cocoons as Type A, whereas number of eggs per cocoon were not different between these Types. Type B also had the lowest mortality in 16-week experiments with changing temperatures.

Section: Introductionmentioning

confidence: 99%

Some characteristics of genetic variants of Tubifex tubifex (M�ller, 1774) (Oligochaeta: Tubificidae) in laboratory cultures

Anlauf

1994

“…6B). The ineffective control was also due to the temporal delay between the time of high egg population density in the culture and the time of a possible reduction in ovigeration percentage (at least 100 days at 20 "C, Bonacina et al, 1987a).…”

Section: Resultsmentioning

confidence: 99%

“…Each mass culture was kept at 20 "C in a 6 cm wide cylindrical glass jar and inspected fortnightly; at every control check the animals were counted according to the biological stage (E = eggs + embryos; Y = youngs; M = mature, but not ovigerous; 0 = ovigerous, i.e. with eggs in the ovisac) and 1 g (wet weight) of deep-frozen lettuce added to the sand (for more culturing details, see Bonacina et al, 1987a).…”

Section: Methodsmentioning

confidence: 99%

“…Additional quantitative observations on the life cycle of this species have been obtained by cohort-culturing and the results incorporated in a population dynamics model (Bonomi & Di Cola, 1980;Adreani et al, 1981) or used for some general conclusions on the interpretation of the species distribution and temporal sequence in the profundal of lakes (Lang & Hutter, 198 1;Adreani et al, 1984;Bonacina et al, 1986Bonacina et al, , 1987a.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Population analysis in mass cultures of Tubifex tubifex

Bonacina¹,

Bonomi

Monti

1989

Self Cite

Mass cultures of Tubifex tubijkx from Lake Orta were kept in the lab at 20 'C starting with different initial densities (10, 45, 86, 161 ind *jar-'), with the aim of evaluating the effect of density on population numbers and on population parameters. The results show that density mainly controls fecundity, growth, maturation and ovigeration rates. Growth rates and mean number of eggs laid/ovigerous (R,) are inversely related to density, but generation time appears to be directly related. Very low or very high initial densities display, at different times of the culture history, efficient density controls. Intermediate N, seem to bring about situations of bad control, easily leading to numerical overshoots. A possible implementation of a population dynamics model (Bonomi & Di Cola, 1980), originally used for laboratory observations on T. tubifex cohorts was considered, including some density control functions derived from our observations on cohort and mass cultures in some transfer rates and in fecundity rate.

“…9) is roughly 105 to 127 days. Bonacina et al (1987 , Table 1) estimated the corresponding time for a number of freshwater lumbriculids and tubiticids in 10 ' C and 15 ' C to be 25 to 100 and 16.5 to 62.7 days, respectively. Brinkhurst (1964), in his study of Tubifx costatus found that cocoons started to occur in the samples in early May, to be replaced by newly hatched juveniles in early July, which would indicate that the embryonic development can be completed in 1 to 2 months in that species.…”

Section: Reproductionmentioning

confidence: 99%

Population dynamics of Tubificoides amplivasatus (Oligochaeta, Tubificidae) in the Oresund, Denmark

Ers�us

Díaz

1989

A two year fortnightly collection of data from the 27 m station in the Oresund on the tubificid species TubiJicoides amplivasatus was analyzed for population trends and life stages. Recruitment patterns from year to year were consistent in timing but very irratic in magnitude, being similar to patterns seen in other estuarine and marine annelids. Sexually mature T. amplivasatus were found throughout the study period, but mature mated specimens were more abundant during late summer and autumn. It is estimated that from 120 to 150 days is spent, by this species, in the cocoon and individuals may reach maturity in less than one year. There was some indication of individuals with regressed genital organs indicating that they may live longer than one year. At the 27 m station T. amplivasatus is part of a complex and well developed benthic community. Temporal variation in this species was highly correlated to that of other major taxa (bivalves, ophiuroids).