Given a wet mass (wet_mass) and buoyant mass (buoy_mass),
this function calculates the density of a specimen. Bouyant mass is the
downward force exerted while the specimen is in water, typically measured
by having a measuring plate within a tank of water suspended from a
balance above the tank. For species such as molluscs this can be used to
determine the ratio of shell to tissue mass. It can also be used to
calculate a specimen volume for correcting the water volume of a
respirometer (see eff_vol). The temperature (t) and
salinity (S) at which the buoyant mass was determined are required (as is
atmospheric pressure (P) which defaults to 1.013253 bar, if not otherwise
specified).
spec_density(wet_mass = NULL, buoy_mass = NULL, t = NULL, S = NULL, P = 1.013253)
| wet_mass | numeric (kg). Wet mass of specimen. |
|---|---|
| buoy_mass | numeric (kg). Buoyant mass of specimen. |
| t | numeric (°C). Water temperature at which |
| S | numeric (ppt). Water salinity at which |
| P | numeric (bar). Atmospheric pressure at which |
Inputs must be in SI units:
wet_mass and buoy_mass in kg
t in °C
S in ppt
P in bar (Defaults to 1.013253)
The function should work with
positively buoyant specimens (i.e. less dense than water). Given a bouyant
weight measured as buoyancy (i.e. lift force on a balance while in water),
this can be entered as a negative value for buoy_mass and the function
should return the correct density value. However, none of this has been
tested.
Output is a single numeric value for the density in kg/m^3.
eff_vol