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Default mass of an egg in OSMOSE

Hi Philippe, 
By default, OSMOSE assumes that the size of an egg is 0.1 cm, and that the mass of an egg is 0.0005386 g, considering a sphere with water density.
If I assume that an egg has a diameter of 0.1 cm (and, therefore, a radius r = 0.05 cm), then under the assumption that the average density of salt water at the surface is 1.025 kg/l = 1.025 g.cm-3, we get an egg mass of 1.025*4/3.pi.r3 = 0.00053669 g. 
This figure (0.00053669 g) is slightly different from the default egg mass in OSMOSE (0.0005386 g). I guess that this is because the figure of 0.0005386 g was calculated while assuming a specific temperature and a specific salinity. 
==> Therefore, my question is: what temperature (in °C) and what salinity did you assume to get an estimate of 0.0005386 g for egg mass? 
Many thanks. 
Cheers, 
Arnaud

Dear Arnaud,

I will have to ask Yunne or Morgane to answer your question. I never questionned these default values and it could either be an error or as you said specific values (more realisitic for Benguela ?..) for sea water temperature and/or salinity.

I get back to you asap.

Cheers, Philippe

Dear Arnaud,

It looks like there is no records about the default  egg mass. You may change this value in your configuration file but I think that the parameter has very little influence on the model outputs.

Cheers, Philippe

 

Dear Philippe,
 
Many thanks for your message.
It is unfortunate that there are no records about the default egg mass.
The default value currently specified in OSMOSE v3u2 (i.e., 0.0005386 g) was probably estimated while assuming a specific value for the density of ocean water (which corresponds to specific depth, temperature and salinity).
However, 0.0005386 / (4/3 * pi * (0.05^3)) = 1.0287 g.cm-3, while the density of ocean water ranges between 1.025 and 1.028 g.cm-3; and 1.028 g.cm-3 is reached at about 1000 m of water depth. Therefore, I am assuming that the default value currently specified in OSMOSE v3u2 (i.e., 0.0005386 g) is not correct, and that a default egg mass of 0.00053669 g would be more appropriate. 
Sorry for sounding pedantic. It is just that I wanted to be able to caculate an egg mass for species whose egg diameter is different from 0.1 cm.
 
Many thanks once again.
Cheers,
Arnaud