Differences in life-cycle traits of<Emphasis Type="Italic"> Calanus finmarchicus</Emphasis> originating from 60°N and 69°N,when reared in mesocosms at 69°N

Two different Calanus finmarchicus (Gunnerus) cohorts originating from 60°N (Bergen) and 69°N (Tromsø) were investigated in equal environmental conditions to study their different physiological responses to the same environment. A two-plus-two-bag mesocosm study was carried out between March and July 1998, in Håkøybotn, Tromsø, in order to determine development and mortality rates of the two parallel cohorts of C. finmarchicus. For practical reasons, the cohort from Bergen was incubated 10 days earlier than the Tromsø cohort. Consequently, they were exposed to elevated food conditions as compared to the Tromsø cohort. A high initial mortality among the Bergen cohort could clearly be ascribed, by genetic discrimination, to "contamination" with C. helgolandicus. After this initial mass mortality, the mortality was constantly 0.03-0.04 day^у. In cohorts starting from naupliar stage I, there was no significant difference in development or growth, the median development time (NI-CIV) differing by only 7 days (~6%). The difference in development time can be explained to a large extent (~4 days) by temperature differences. This is substantiated with model simulations using a physiological model developed for C. finmarchicus. There was a time lag in incubation between the two cohorts, resulting in elevated temperature during incubation of the Tromsø cohort. A fraction of both cohorts differentiated sexually at stage CV, with males differentiating before females. Females from both cohorts produced eggs, but specific egg production differed significantly (P>0.001, t-test). This was supported by elevated RNA:DNA ratio in females from the Bergen cohort. Both cohorts demonstrated quite similar development and physiological growth rates and, consequently, are considered to belong to the same genetic population inhabiting the Norwegian Shelf. The study demonstrates that C. finmarchicus is capable of adaptation to changes in environment and, thereby, demonstrates a significant physiological plasticity.     

Subitaneous, diapause, and delayed-hatching eggs of planktonic copepods from the northern Gulf of Mexico: morphology and hatching success

Experiments were conducted to examine the morphology and hatching success of eggs, either spawned by freshly caught planktonic copepods or recovered from bottom sediments in the northern Gulf of Mexico. Collections were made between August 1992 and September 1995. Eggs of nine species were described and these differed in their diameter, color and surface attributes. Three types of eggs were distinguished: subitaneous, diapause, and delayed-hatching. Three species, Labidocera aestiva Wheeler, Acartia tonsa Dana, and Centropages velificatus (Oliveira) produced only subitaneous eggs. Hatching success varied greatly among these species. Two species, Labidocera mirabilis Fleminger and Centropages hamatus (Lilljeborg) produced diapause eggs and subitaneous eggs. The length of the refractory phase of the diapause eggs differed greatly both within and between these two species. A third type of dormant egg, delayed-hatching, was recognized in Labidocera scotti Giesbrecht and Pontella meadi Wheeler. The existence of delayed-hatching eggs may be an adaptive response of subtropical species to less seasonal fluctuation. Based upon morphological characteristics of the eggs and rearing of nauplii to an identifiable stage, benthic dormant eggs of eight species of calanoid copepods were also identified. Received: 9 September 1996 / Accepted: 1 October 1996     

An object-oriented software for fate and exposure assessments

The model system CemoS¹ (Chemical Exposure Model System) was developed for the exposure prediction of hazardous chemicals released to the environment. Eight different models were implemented involving chemicals fate simulation in air, water, soil and plants after continuous or single emissions from point and diffuse sources. Scenario studies are supported by a substance and an environmental data base. All input data are checked on their plausibility. Substance and environmental process estimation functions facilitate generic model calculations. CemoS is implemented in a modular structure using object-oriented programming. e-mail: cemos@aphrodite.mathematik.uni-osnabrueck.de     

Environmental effects on the distribution of corallimorpharians in Tanzania

This study examined the distribution and abundance of corallimorpharians (Cnidaria, Anthozoa) in Tanzania in relation to different aspects of the coral reef environment. Five reefs under varying degrees of human disturbance were investigated using the line intercept transect and point technique. Corallimorpharian growth and the composition of the substratum were quantified in different habitats within reefs: the inner and middle reef flat, the reef crest, and at the 2 and 4 m depths on the reef slope. Corallimorpharians occurred on all the reefs and 5 species were identified: Rhodactis rhodostoma, R. mussoides, Ricordea yuma, Actinodiscus unguja and A. nummiforme. R. rhodostoma was the dominant corallimorpharian at all sites. Within reefs, they had the highest densities in the shallow habitats. While R. rhodostoma occurred in all habitats, the other corallimorpharian species showed uneven distributions. Corallimorpharians ranked second, after scleractinian coral, in percent living cover. Results from this study suggested that corallimorpharians benefitted from disturbance compared with other sessile organisms. They preferred inhabiting areas with dead coral, rock and rubble whilst live coral was avoided. There was a positive relationship between percent cover of corallimorpharians and water turbidity and they dominated the more disturbed reefs, i.e. reefs that were affected by higher nutrient loads and fishing.     

Bioavailability of HOC depending on the colloidal state of humic substances: a case study with PCB-77 and Daphnia magna

Condensed organic matter with higher affinity for hydrophobic organic compounds (HOC) is currently held responsible for slow desorption and concomitant lower bioavailabilities of HOC in sediments and soils. In an experiment with Daphnia magna and IHSS Peat Humic Acid (PHA), we showed that the bioconcentration factor (BCF) of 3,3',4,4'-tetrachlorobiphenyl (PCB-77) was directly related to the charge of the humic colloid, as predicted by the metal-humic binding model WHAM. Consistent with the type of binding to the humic acid (counter-ion accumulation vs. specific binding), increasing the concentration of Na+ and Ca2+ ions generated opposite effects on colloid charge and HOC binding by the humic acid. Condensation as a colloidal phenomenon in solution as well as on surfaces needs to be addressed as a contributor to lower bioavailabilities and, possibly, to slower desorption kinetics.     

Das neue Chemikalienprogramm von UNEP Chemicals

Zusammenfassung  UNEP International Register of Potentially Toxic Chemicals (IRPTC) wurde von der ersten VN-Umweltkonferenz 1972 geschaffen. Sein Einfu? und Zusammenwirken in den 80ziger Jahren mit anderen internationalen Programmen der WHO, FAO, OECD und EG in der Chemikalienkontrolle wird beschrieben. Nach dem Erdgipfel von Rio 1992 werden im VN-Rahmen drei neue Gremien gebildet, die das Fachprogramm des Kapitels 19 der Agenda 21 (umweltfreundliches Chemikalienmanagement) umsetzen sollen: die United nations Commission of Sustainable Development, das Intergovernmental Forum on Chemical Safety und das Interorganization Programme for the Sound Management of Chemicals. Der Erdgipfel brachte auch für IRPTC eine Neuorientierung. Seit 1996 hat UNEP Chemicals, wie sich IRPTC nunmehr nennt, drei Aufgaben in sein Arbeitsprogramm aufgenommen, die beschrieben werden: das internationale übereinkommen zum Prior Informed Consent, das internationale übereinkommen zur Kontrolle der Persistent Organic Pollutants, und schlie?lich sein traditionelles Arbeitsgebiet des Informations-austausches über Stoffe wird weitergeführt.

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