ISSN:
1438-3888
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The spionid polychaete speciesPolydora ligni, P. ciliata, andPygospio elegans were cultivated in the laboratory over several successive generations. A flow-through cultivation system forPolydora spp. is described. Duration of life cycles (time from hatching of the larva to first reproduction) and life spans (hatching to death) of these species were not significantly influenced by the degree of inbreeding nor by individual age of the parents. Minimum time from metamorphosis (15-setiger stage) to first hatching of offspring larvae (in the 3-setiger stage) at 18°C was 33 days inPolydora spp. and 81 days inPygospio elegans. Larval growth patterns are described in terms of number of setigers, body length, and biomass (dry weight, carbon, nitrogen, hydrogen), in relation to time after hatching. Regression models are proposed which link these measures of larval growth and, thus, may be used for conversions. Rates of development and growth show a high degree of variability in all three species, not only caused by variation in environmental factors such as temperature or food, but also among and within single hatches of larvae reared under identical conditions. Larvae were reared at constant temperatures (6°, 12°, and 18°C). Temperature affected larval growth inPolydora ligni more than inP. ciliata, and least of all inPygospio elegans. Only the latter species was able to develop at 6°C from hatching to metamorphosis. This differential response may be explained by differences in the natural spawning season of these species. Eleven phytoplankton species were tested as to their food values. A “relative index of growth” is proposed which compares the slopes of two growth curves (one standard and one test condition). The flagellateDunaliella tertiolecta was used as a standard food in these experiments. Most algal species were less suitable, and only the diatomThalassiosira rotula was consistently better food for spionid larvae thanD. tertiolecta.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01983819
