H. von Westernhagen

Combined effects of cadmium and salinity on development and survival of herring eggs

KurzfassungEier des herbstlaichenden Ostseeherings (Clupea harengus L.) wurden in natürlichem und in Cadmium kontaminiertem Seewasser (Konzentrationen: 0,1; 0,5; 1,0; 5,0 ppm Cd) bei verschiedenen Salzgehalten (5 ‰ 16 ‰ 25‰ 32‰) erbrütet. Die Toxizität von Cd wurde im Hinblick auf folgende Kriterien bewertet: Embryoaktivität und Überlebensraten bis zum Schlupf, Veränderungen der Eimembran, Verschiebung des Schlupfzeitpunktes, Unterschiede in den Schlupfraten, Anteil der lebensfähigen Larven und deren mittlere Totallänge sowie Durchmesser der Augen und Gehörkapseln frischgeschlüpfter Larven. Darüber hinaus wurde die Aufnahme von Cd in Abhängigkeit von Konzentration und Salzgehalt im Verlauf der Embryonalentwicklung bestimmt. Die Beeinträchtigung der Heringsembryonen durch Cd war in brackigem Wasser stärker als in unverdünntem Meerwasser. Auch die konzentrationsabhängige Aufnahme von Cd nahm mit sinkendem Salzgehalt des Erbrütungsmediums zu.Summary1. Eggs of autumn spawning Baltic herring (Clupea harengus L.) were incubated in cadmium-contaminated water (0, 0.1, 0.5, 1.0, 5.0 ppm) at four salinities (5 ‰, 16 ‰, 25 ‰, 32 ‰) in order to evaluate possible changes in toxicity of Cd.2. Effects of Cd on embryonic survival were found to be dependent on salinity of the incubating water. Deleterious effects of Cd on developing herring embryos were more pronounced in brackish water than in sea water.3. Embryonic activity, as a measure of viability of developing embryos, decreased in Cd concentrations with decreasing salinity.4. In none of the trials was egg diameter altered by the Cd content of the incubation water.5. In all salinities, incubation time appeared to be shortened with increasing Cd content of the test medium.6. At 5 ‰, 16 ‰, 25 ‰ and 0, 0.1, 0.5 and 1.0 ppm, hatching rate was not significantly altered by Cd. High hatching rates between 85 to 99% occurred in all salinity-Cd combinations. At high Cd levels (5.0 ppm), there was greater survival of embryos at high salinities (32 ‰ and 25 ‰) than at low salinities (16 ‰ and 5 ‰).7. Percentage viable hatch was unaffected at 32 ‰, 25 ‰ and 16 ‰ S and 0, 0.1 and 0.5 ppm Cd. In low salinities (5 ‰), only 1% viable hatch occurred at 0.5 ppm; in 16 ‰, 61.5 % viable hatch occurred at 1.0 ppm Cd. No viable larvae were obtained in any tests at 5.0 ppm Cd.8. In all salinities examined, mean total length of newly hatched larvae decreased with increasing Cd concentration of the rearing medium. Relative decrease in mean total length was minimum at 32 ‰ S.9. In all four test concentrations yolk sac volumes of newly hatched larvae increased with rising Cd concentrations, probably associated with declining embryo activity.10. The Cd content of eggs was found to be generally higher in lower salinities than in more saline water at comparable Cd concentrations.

Erbrütung der Eier von Dorsch(Gadus morhua), Flunder(Pleuronectes flesus) und Scholle(Pleuronectes platessa) unter kombinierten Temperatur- und Salzgehaltsbedingungen

Eggs of Baltic cod (Gadus morhua L.), flounder (Pleuronectes flesus L.) and plaice (Pleuronectes platessa L.) have been reared under combined temperature and salinity conditions (0°–16° C, 7‰–42‰ S). Combined temperature and salinity influences on embryonic development were investigated. Optimum temperatures for the rearing of cod eggs range from 4° to 8° C, and optimum salinities from 20‰ to 33‰ S. Flounder eggs develop best at 4° C and in 33‰ S, and plaice eggs at 6° C and in 20‰ S. Suboptimum conditions result in lower percentages of larval hatching and survival, and increased morphological anomalies such as curvature of tail and body. Low salinities (20‰ and 15‰ S) cause swollen yolk sacs which, in experiments with flounder eggs, lead to jaw deformities. Rearing at low salinity decreases speed of development. Optimum salinity varies as a function of incubation temperature and influences variations in optimum rearing temperature. Extremely low salinities (20‰ and 15‰ S) are tolerated best at optimum or lower temperatures. From the results of these experiments it can be concluded that brackish water races of these fishes are likely to exist in the Baltic Sea.Zusammenfassung1. Die Eier von Dorsch (Gadus morhua L.), Flunder (Pleuronectes flesus L.) und Scholle (Pleuronectes platessa L.) der westlichen Ostsee wurden unter kombinierten Salzgehalts-Temperaturbedingungen (0°–16° C, 7‰–42‰ S) erbrütet. Es wurde untersucht, inwieweit die Embryonalentwicklung durch das Zusammenwirken von Temperatur und Salzgehalt beeinflußt wird.2. Die optimalen Temperatur- und Salzgehaltsbereiche für die Erbrütung von Dorsch, Flunder und Scholle wurden festgestellt. Für den Dorsch konnten drei Versuche mit unterschiedlichem Material durchgeführt werden. Die optimalen Temperaturund Salzgehaltskombinationen für die Erbrütung von Dorscheiern betrugen: (a) 6°–8° C bei 25‰–30‰ S, (b) 4° C bei 20‰–33‰ S und (c) 4°–6° C bei 33‰ S. Für die Flundereier wurde als optimale Temperatur-Salzgehaltskombination 4° C und 33‰ S gefunden. Die untersuchten Scholleneier entwickelten sich bei 6° C und 20‰ S am besten.3. In nicht-optimalen Temperatur- und Salzgehaltsbereichen war ein Absinken der Überlebensrate und verstärktes Auftreten morphologischer Anomalien an Embryonen und Larven zu verzeichnen. Als charakteristische Schädigungen traten Verkrümmungen der caudalen Körperregion auf. Larven, die in schwach salzigem Wasser gehalten wurden (20‰ und 15‰ S), litten an Dottersackquellung, was bei den Flunderlarven zu Kieferdeformationen führte.4. Als wahrscheinliche Ursache für die Verkrümmungen und Verwachsungen des Schwanzes wurde ein durch extreme Temperaturen allgemein gestörtes Zusammenwirken der Enzyme diskutiert.5. Die Wirkung hoher und niedriger Salzgehalte wurde in der Diskussion auf eine Störung im embryonalen Stoffwechsel zurückgeführt, die durch Änderung im Ionenmilieu der Zelle hervorgerufen wird.6. Mit zunehmender Aussüßung des Erbrütungswassers konnte bei allen untersuchten Eiern Entwicklungsverlangsamung beobachtet werden. Bei hohen Erbrütungstemperaturen wurden die Unterschiede in der Entwicklungsgeschwindigkeit geringer.7. Der für die Erbrütung optimale Salzgehalt änderte sich in Abhängigkeit von der Inkubationstemperatur. Ebenfalls war die optimale Erbrütungstemperatur in Abhängigkeit vom Salzgehalt des Erbrütungsmediums veränderlich. Extrem niedrige Salzgehalte (15‰ und 20‰ S) wurden im Bereich der Optimaltemperaturen oder bei niedrigen Temperaturen besser ertragen.8. Bei allen drei untersuchten Fischarten wurde das Auftreten von Brackwasserrassen in der Ostsee erörtert und für wahrscheinlich gehalten.

Laboratory and in-situ studies on larval development and swimming performance of Pacific herringClupea harengus pallasi

Pacific herringClupea harengus pallasi larvae were caught alive in Departure Bay, B.C., Canada, after being attracted towards light. Growth of larvae was observed during a 5-week period. Larval total length (measured in live anaesthetized specimens) during this period increased from 8 mm to 28 mm. Development of condition factor was observed through the yolk-sac stage until the early post yolk-sac stage. Condition factor decreased linearly in yolk-sac larvae and increased in post yolksac specimens. Swimming performance of Pacific herring larvae in their natural habitat was studied during the day by means of direct observations and compared with laboratory investigations conducted with “wild” and laboratory-reared larvae. In the laboratory (black 35-cm diameter tanks, 10°C) “wild” larvae swam more slowly and were less active (measured as % active time) than in their natural habitat. Laboratory reared larvae showed depressed activity when compared with “wild” larvae observed in the sea. This phenomenon was attributed to deprivation of stimuli in confined containers which might have some bearing on the validity of data gained from controlled ecosystem experiments.

Fate and effects of cadmium in an experimental marine ecosystem

Two recirculated marine seawater systems (capacities: 150 and 300 l) were used for the study on cadmium accumulation of biological filter sludge, by the musselMytilus edulis and the plaicePleuronectes platessa for a period of up to 300 days. In the contaminated system Cd concentrations varied from 2.5 to 7.0 μg/l with a mean of 4.6±1.15 μg/l (control: 1.04±0.46 μg/l). Accumulation of Cd by the filter sludge from the control system as well as from the contaminated system was significant. Mean concentrations of control-and contaminated sludge over the experimental period were 2.01±0.86 ng Cd/mg dry wt and 9.98±3.55 ng Cd/mg dry wt respectively. Accumulation of Cd byM. edulis both in the control and in the contaminated system was considerable. After 163 days of exposure the whole body burden of mussels rose from 0.3 ng Cd/mg dry wt to around 10 ng Cd/mg dry wt in the controls and to 70 ng Cd/mg dry wt in the contaminated systems. Accumulation of Cd byP. platessa was analysed in backbone, fins, gills, liver, muscle (fillet), otolith and skin (dorsal and ventral) over a period of 280 days. Elevated Cd contents of livers from control specimens were noticed after 200 days and reached 1.75 ng Cd/mg dry wt in liver. There was considerable accumulation in the liver (maximum values: 3.0 ng Cd/mg dry wt) and gills (6.0 ng Cd/mg dry wt) of specimens from the contaminated system, Cd contents of plaice exposed for identical periods of time were very variable. Growth of plaice living in the contaminated system was at times significantly slower than that of the control group. Of the three biological objects tested-filter sludge,M. edulis, P. platessa—the mussel seemed to be the most sensitive indicator of elevated Cd-concentrations, while the reaction of the plaice was slow and less distinct.

Multivariate statistical approach to the temporal and spatial patterns of selected bioindicators observed in the North Sea during the years 1995–1997

Abstract A comprehensive database, containing biological and chemical information, collected in the framework of the bilateral interdisciplinary MARS project (”biological indicators of natural and man-made changes in marine and coastal waters”) during the years 1995–1997 in the coastal environment of the North Sea, was subjected to a multivariate statistical evaluation. The MARS project was designated to combine a variety of approaches and to develop a set of methods for the employment of biological indicators in pollution monitoring and environmental quality assessment. In total, nine ship cruises to four coastal sampling sites were conducted; 765 fish and 384 mussel samples were analysed for biological and chemical parameters. Additional information on the chemical background at the sampling sites was derived from sediment samples, collected at each of the four sampling sites. Based on the available chemical data in sediments and black mussel (Mytilus edulis) a pollution gradient between the selected sites, was established. The chemical body burden of flounder (Platichthys flesus) from these sites, though, did not reflect this gradient equally clear. In contrast, the biological information derived from measurements in fish samples displayed significant a regional as well as a temporal pattern. A multivariate bioindicator data matrix was evaluated employing a factor analysis model to identify relations between selected biological indicators, and to improve the understanding of a regional and temporal component in the parameter response. In a second approach, applying the k-means algorithm on the data matrix, two significantly different clusters of samples, characterised by the current health status of the fish, were extracted. Using this classification a temporal, and in the second order, a less pronounced spatial effect was evident. In particular, during July 1996, a clear sign of deteriorating environmental conditions was extracted from the biological data matrix.

Rearing and spawning siganids (Pisces: Teleostei) in a closed seawater system

KurzfassungAus den Philippinen importierte Jungfische vonSiganus oramin undS. concatenata (S. guttatus?) wurden bei 26° C und 32‰ S im geschlossenen Seewasserkreislauf mit verschiedenen kommerziellen Kunstfuttersorten (Hühnerfutter, Kaninchenfutter, Tetramin) aufgezogen und das Längen- und Gewichtswachstum über 26 Wochen verfolgt. Nach dieser Zeit wurden die ersten Tiere geschlechtsreif und durch mehrfache Hormoninjektionen (HCG) zum Abstreifen vorbereitet. Die künstliche Befruchtung der Eier gelang beiS. oramin mehrfach. Die Befruchtungsversuche wurden bei 12,1, 15,8, 20,9, 30,6, 32,2‰S und 26° C durchgeführt. Zwischen 20,9 und 32,2‰ S betrug die Befruchtungsrate 95% und darüber. Die Embryonalentwicklung und die Larvalentwicklung während der Dotterzehrung werden beschrieben.Summary1.Two species of signaids from The Philippines,Siganus oramin andS. concatenata (S. guttatus?), were reared in a closed sea water system and fed different artificial feeds.2.A comparison between commercial chicken and rabbit feeds in regard to their suitability as siganid feeds led to the conclusion that for this purpose the latter was the more appropriate diet.3.Within six months juvenileS. oramin (4–6 cm, 2–6 g) reached maturity and were treated with human chorionic hormone (HCG) in order to induce ovulation.4.Two females were successfully stripped after having received HCG injections. The eggs were artificially inseminated and incubated at 15.8, 20.9, 30.6 and 32.2‰ S.5.Early embryogenesis was evaluated by means of time lapse movie pictures (two frames/min).6.Incubation of the eggs at 26°–28° C took 29 h from fertilization to hatching. Viable larvae hatched only between 20.9 and 32.2‰S and larval survival was best in 32.2‰S. There was no viable hatch at 15.8‰S, and no fertilization occured at 12.1‰S.

Cadmium uptake by marine fish larvae

KurzfassungEier von Hering, Flunder und Hornhecht wurden in Cadmium kontaminiertem Wasser (0,05–5,0 ppm) erbrütet und frisch geschlüpfte Larven auf ihren Gehalt an Cadmium untersucht. Der Cadmiumgehalt frisch geschlüpfter Larven war von den während der Erbrütung angewandten Konzentrationen abhängig. Kontamination von Flunder- und Heringslarven (0,7–2,3 ng Cd/0,1 mg Trockengewicht) war um zwei Zehnerpotenzen höher als der Cadmiumgehalt von Hornhechtlarven, die unter den selben Bedingungen erbrütet worden waren (0,0017–0,0185 ng Cd/0,1 mg Trokkengewicht). Der Cadmiumgehalt von Flunder- und Heringslarven stieg mit der Expositionsdauer an. Nach 8 Tagen enthielten Heringslarven 48 ng Cd/0,1 mg Trockengewicht, während in Flunderlarven nur 5,4 ng Cd/0,1 mg Trockengewicht gemessen wurden. Der Cadmiumgehalt von Hornhechtlarven und -Juvenilen, die bei 0,05 ppm Cd 34 Tage gehalten wurden, war signifikant höher als in Kontrolltieren.Summary1.Eggs of herring(Clupea harengus), flounder(Platichthys flesus), and garpike(Belone belone) were incubated in cadmium contaminated water (0.05–5.0 ppm) and newly hatched larvae analyzed for cadmium contents.2.Cadmium residues in newly hatched larvae were dependent on cadmium concentrations employed during incubation.3.Cadmium contents of newly hatched flounder and herring larvae (0.7–2.3 ng Cd/0.1 mg dry weight) were of two orders of magnitude higher than inBelone belone larvae incubated under the same conditions (0.0017–0.0185 ng Cd/0.1 mg dry weight).4.Cadmium contents of herring and flounder larvae held in cadmium contaminated water increased with exposure time.5.Cadmium contents of herring larvae exposed to cadmium contaminated water for 8 days were of one order of magnitude higher than contamination of flounder larvae kept under similar conditions (max. value for herring 48 ng Cd/0.1 mg dry weight; max value for flounder 5.4 ng Cd/0.1 mg dry weight).6.Cadmium contents ofBelone belone larvae and juveniles kept at 0.05 ppm Cd for 30 days were significantly higher than cadmium contamination of control specimens.

Effect of the surfactant Corexit 7664 on uptake of cadmium by organisms and biological matter in a closed circulated brackish-water system

Juvenile flounder and common mussel from the Baltic Sea were kept in Corexit 7664 (50 µg/l) and cadmium (5 µg/l)-contaminated, recirculated, sea-water systems for 200 days at 15 °C and 20 ‰ S. Accumulation of cadmium with exposure time was measured in several fish tissues and in mussel. There were no differences in the cadmium accumulation by tissues with or without the addition of Corexit 7664. No acute effects of the contaminants on the experimental animals could be noted. Final cadmium concentrations, reached for all biological matter analysed, were 4 times higher than in full-strength sea water.