Life cycle strategies linked to adult development and reproduction in the Northern krill, Meganyctiphanes norvegica. Study of the Gullmarsfjorden population.

Updated 2003-07-10

To recognize some life cycle strategies linked to adult development and reproduction in the Northern krill, Meganyctiphanes norvegica, in the Gullmarsfjorden population. Sampling of krill and analyses of the distribution of sex, body-size, moult and reproductive development stages.

Time frame

Status
Completed
Project time span
1998 - 2000
Data collection
2000 - 2000
Data processing
not specified
Data reporting
not specified

Contact information

Contact person
Janine Cuzin-Roudy
Address
LOBEPM-Observatoire Océanologique UPMC-CNRS-INSU BP 28 06230 Villefranche sur mer France
Phone
+33 493763827
Fax
+33 493763848
Email
-

Parameters and Media

Parameter groups measured/observed/modelled
Biological effects
Media sampled/studied/modelled
Plankton (zooplankton)

Geography

Regions studied
Kristineberg Marine Research Station
Sweden
Other areas
The Gullmarsfjord

Data availability

Samples/specimens archived in specimen banks?
No

Methods & Procedures

Procedures and methodology used for, e.g., sampling and sample storage, sample pretreatment, extraction and analysis, including which laboratories are involved, references to methods employed, etc.

Adult krill (Meganyctiphanes norvegica) were sampled during the day at 90-100m depth in the fjord on the 1/8/00. Other day and night samples were preserved at weekly intervals for a further analysis of the distribution of sex, body-size, moult and reproductive development stages. From a large field sample, hundred live krill were immediately transferred to 1 litre jars, maintained in running sea water at 8degrC and fed daily with Artemia nauplii, for the establishment of the inter-moult period (IMP) and moult stages duration. The temperature was chosen as an average of the in situ temperatures encountered by krill during their vertical migrations: 6 degrC from 60m depth and below during the day; up to 16degrC at 20m during their vertical migration at night. Percentage of moulting krill were recorded daily, until 100% of the krill sample had moulted. At the end of the experiment, all krill were checked for the moult stage attained and the duration of the different moult stages was established. IMP was estimated as IMP=18 days at 8degrC, directly for krill which moulted twice during the experiment; from the cumulative moult frequencies; and by adding the average duration of the successive moult stages. As expected, IMP was longer than IMP=12 days established in 9/99, for krill from the same population maintained at a temperature of 9degrC, but also longer than expected from the relationship of IMP with temperature established for other krill populations. During the experiment, daily moult frequency was high, then low and finally very high, showing a clear trend for a synchrony in moulting for individual krill, as already observed in sept 99 sampples, together with spawning synchrony. This point is studied in collaboration with F. and C Buchholz and should be strengthen by the analysis of their field samples and our preserved samples.

Additional Information

Is this a bi- AND multi-lateral project (i.e. a project involving cooperation between different countries)?
No
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