Harald Rosenthal

Bioaccumulating substances and reproductive success in baltic flounder platichthys flesus

Abstract Running ripe Baltic flounder Piatichthys flesus were caught with a bottom trawli. Eggs were stripped and artificially inseminated and incubated in Baltic sea water at 6.8 °C and a salinity of 27.5% After hatching, siraight and viable appearing larvae — viable hatch — were determined. Ovary and liver samples of the female parental fish were collected and analyzed for chlorinated hydrocarbons and heavy metals. Viable hatch was significantly affected at ovary chlorinated hiphenyl (PCB) levels higher than 120 ng/g wet weight. Thus 120 ng/g PCB was designated a threshold level in flounder eggs. above which reduced survival of developing eggs and larvas can be expected. Other chlorinated hydrocaihons. and metals did not show any correlation between ovary and/or liver contamination levels and viable hatch. The melhod employed is deemed to be a promising tool for the assessment of pollution effects on marine biola.

Growth of European sea bass (Dicentrarchus labrax L.) under hypoxic and oscillating oxygen conditions

Effects of moderate hypoxia and oscillating oxygen conditions on growth of European sea bass (Dicentrarchus labrax L.) were investigated. Groups of four to six sea bass (initial weights 40–90 g) were exposed to one of three oxygen regimes (40% air saturation; oscillations between 40–86% with a period of 770 min; 86% as a control) at 22°C and a salinity of 37 for 1 month. All fish survived and gained weight, but relative to the controls, the sea bass exposed to hypoxic conditions consumed significantly less food, exhibited a reduced growth, and had a lower condition factor. Oscillating groups were intermediate, and not statistically distinguishable from either normoxic or hypoxic treatments. Feed conversion efficiency and variation in body size were not significantly affected by oxygen conditions. Growth was correlated with feed intake, suggesting that reduced growth under moderate hypoxic or oscillating oxygen conditions is primarily due to reduced appetite and not a consequence of a decrease in feed conversion efficiency.

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.

Chlorinated hydrocarbons and hatching success in Baltic herring spring spawners

Abstract Eggs from 69 females of spring spawning herring from the German Baltic coast (Travemunde, April 1979) were incubated in clean sea water (20‰ S, temperature 8°C) under standard conditions. Sixty-one trials could be used for the evaluation of hatching success. Viable hatch was taken as a measure to evaluate the effects of chlorinated hydrocarbons accumulated in gonads, liver and muscle of parental fish. PCB levels in running ripe females ranged on a wet weight basis between 19 and 241 ng g −1 (gonad), 20 and 377 ng g −1 (liver) and 11 and 1820 ng g −1 (muscle). Concentrations of other chlorinated hydrocarbons (DDD, DDE, γ-HCH, etc.) were in the same range as reported by other authors for Baltic herring (Huschenbeth, 1973, 1977). Viable hatch was significantly affected at ovary DDE concentrations higher than 18 ng g −1 (wet wt) and PCB concentrations of more than 120 ng g −1 (wet wt). Results are compared with data obtained during earlier investigations with flounder eggs.

A discussion of the use of the sustainability index: 'ecological footprint' for aquaculture production.

This paper critically reviews the theoretical and practical implications of adopting the original ‘ecological footprint’ concept as an index of the sustainability of aquaculture production systems. It is argued that the concept may provide a reasonable visioning tool to demonstrate natural resource dependence of human activities to politicians and the public at large. However, due to its inherent weaknesses, the ‘ecological footprint’ fails to provide a cohesive analytical tool for management. From an ecological perspective, its two-dimensional interpretation of complex ecologically and economically interacting systems is one major weakness. From an economic perspective, the ‘footprint’ fails to recognise factors such as consumer preferences and property rights which have a major influence on the allocation and sustainable use of resources. The interactions among social, ecological and economic factors are discussed in an attempt to foster a broader inter-disciplinary view of criteria required for a sustainable use of aquatic resources.

Combined effects of cadmium, copper and lead on developing herring eggs and larvae

Eggs of Baltic herring were incubated (10°C; 16‰S) in sea water containing mixtures of Cd, Cu and Pb at concentrations of 0.56–5.0, 0.0167–0.15, 0.56–5.0 mg metal/l; embryonic survival until hatching, viable hatch and uptake of metals by embryos and early larvae were measured. Negative effects of metals on embryonic survival and viable hatch were additive in the case of Cu and Cd. Pb did not exer detrimental effects. Uptake of metals with exposure time was non-linear in eggs and linear in larvae. Total uptake of Cu and Cd by eggs was subjected to antagonistic or synergistic action of the other two metals present. Accumulation of Pb by eggs was enhanced when Cu was also present.

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.

Correlation between Cadmium Concentration in the Water and Tissue Residue Levels in Dab, Limanda Limanda L., and Plaice, Pleuronectes Platessa L.

Although cadmium concentrations of unpolluted sea water are low, ranging from 0.01 to 0.41 µg/1 (Goldberg, 1965; Preston, 1973; Chester & Stoner, 1974; Kremling & Petersen, 1977) concentrations in estuaries are from 10 to 100 times higher, as reported by Butterworth, Lester & Nickless (1972) for the Severn and Eustace (1974) for the Derwent estuaries. Unusually high cadmium concentrations of 50 µg/1 have been found by Chan, Cheung & Li (1974) in Hong Kong harbour water. The cadmium in the drinking water (225 µ/l) and the food (rice) of Japanese farmers is believed to have caused the ‘itai-itai’ disease (Kobayashi, 1971), a pathological syndrome characterized by kidney damage with bone disease.

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.