Structural effects of bottom and surface water samples from two dumping grounds in the inner German Bight on the development of three meroplanktonic organisms (Pomatoceros triqueter: Polychaeta, Psammechinus miliaris: Echinodermata and Crassostrea gigas, Mollusca) were investigated. The titaniumdioxide dumping site was sampled immediately after dumping (within the visible waste trail 1 km behind the vessel), and 10 h after dumping. Samples were taken in the sewage sludge deposition area in the intervals between the usual dumping activities, regardless of the exact dumping schedule. The preserved bioassay test organisms were inspected microscopically to count percentages of "normal" larval hatch in test water samples, reference water samples and laboratory aged control water samples (5 to 10 replicates). The relative water quality at various dumping sites was expressed in terms of "net risk--values (Woelke, 1972) compared to hatching rates observed in the controls. Larval development of P. triqueter was significantly suppressed (up to -22 % "net risk") in trail water of the titanium dioxide dump site while the development of sea urchin larvae was still affected in the 10 h surface samples. Hatching of all test organisms in bottom-water samples from the centre of the sewage sludge dump site was affected to different degrees when compared to reference areas about 4 km north or 6 km northwest of the dumping area. The general usefulness of standardized bioassay procedures in pollution monitoring programmes is discussed. The results presented here call for further verification to minimize experimental background variability and to enlarge the catalogue of suitable effects criteria. INTRODUCTIO~
On the ecology of Pomatoceros triqueter (Serpulidae, Polychaeta). II. Influence of temperature on tolerance, regeneration of the tube, oxygen consumption and filtration activity. Based on previous studies (K16ckner, 1976b) dealing with field investigatSons on breeding season, choice of substratum, growth and mortality of the sessile filter-feeding tube worm Pomatoceros triqueter in Helgoland waters (southern North Sea), data from laboratory experiments on the physiological potential of the polychaete in regard to temperature are presented. Adult worms tolerated temperatures from -3 ~ C (24 h LT 28) to 30 ~ C (24 h LT 50) when heated or cooled in steps of i C ~ d 1; a two-week period of acclimation within 6 ~ to 18 ~ C did not change their tolerance. Standard oxygen consumption and regeneration of the calcareous tube were found to be dependent on temperature, body weight and food supply; acclimation periods of two weeks had no significant influence. Highly increasing metabolic rates were noted between 6 ~ and 18 ~ C (Q10-values up to 6) and .a maximum was found between 20 ~ and 24 ~ C (0.32 #g 02 mg-Ih -~ and 10.2 #g CaCO8 mg-ld-1); tube regeneration followed a nonlinear regression of y = ax -b when compared to body weight and was reduced by starving animals to less than 50 ~ within 15 days. Filtration activity of P. triqueter, however, was found to be highly independent of temperature from 12 ~ to 24 ~ C; maximum activity was 1 ml mg -1 h -'1 (all data refer to fresh weight). For comparisons with the results of previous field investigations on P. triqueter some intraspecific correlations of the different parameters employed (tube sizes, fresh and dry weight) are presented as exponential functions of y = axb. EINLEITUNG
Cadmium uptake by the deposit-feeding polychaete Ophryotrocha diadema is a non-linear process related to exposure time and metal concentration in the ambient seawater (20°C; 31 OjmS). Maximum body loads of 1700ppm Cd were found in adult worms (up to 0.1 mg dry weight) after 64-day exposure to 1OOOppb Cd. Distinct saturation of absorption was not reached d u r~n g this time. Accumulation factors decreased exponentially with increasing contamination levels. Accumulation factors were 7900 to 1700, calculated on a dry weight basis, corresponding to 3400 to 660 estimated on a theoretical volume basis of single worms in levels of 10 to lOOOppb Cd. Cd content of 62-to 116-day-old worms of three consecutive generations subjected to permanent contanl~nat~on did not increase from the P-to the F,-generat~on. A linear correlation exists between Cd absorption of newly deposited egg masses and experimental Cd concentrations. Cd loads of egg masses were extremely low (12 to 280ppm Cd dry weight in 50 to lOOOppb Cd contamination) compared with parental organisms. Cd content of the egg masses also did not increase within consecutive generations. It is, therefore, assumed that parentally accumulated Cd loads are not transferred to the offspring. Contamination of egg masses probably occurred after spawning, due to sorption of the metal by the mucoid layer encapsulating the eggs, since similar results were noted for Cd sorption by food part~cles (fragmented spinach).
On the ecology of Pomatoceros triqueter (Serpulidae, Polychaeta). I. Breeding season, choice of substratum, growth and mortality. The sessile, filter-feeding tube wormPomatoceros triqueter (L.), which occurs on solid substrata such as rocks or shells, is eurybathic in Helgoland waters (southern North Sea). The paper presents data from 1970 to 1972 on the season of larval settlement, settlement behaviour of larvae, as well as on growth and mortality rates of adults, It compares results of fouling experiments at two shallow sites on the rocky base (each 7 m deep) and of dredging samples in a local depression southwest of the island Helgoland (30 to 60 m deep). In all three habitats, larval settlement occurred from late summer to autumn. Settling larvae on exposed panels were found to be negatively phototactic; surface structure and material of substratum, however, had no significant effect on abundance. Secondary settlers showed gregarious behaviour, o~en settling near or upon adults. Monthly growth rates of tubes were significantly higher at the shallow sites, this obviously being due to higher temperatures and greater phytoplankton levels in surface waters in spring and summer. Tube growth was probably also influenced by the season of settlement, and by sexual maturity. Natural mortality of juvenile worms, which was high at all sites, varied with season. It reached a maximum in late autumn, when phytoplankton supply was approaching a minimum and water temperatures were declining. The data presented here are compared with the findings of other authors on breeding, settlement, growth and mortality within the boreal-mediterranean range of the species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.