eelgrass {isotracer}

Eelgrass phosphate incorporation data (McRoy & Barsdate 1970)

Description

Dataset built from the article "Phosphate absorption in eelgrass" by McRoy and Barsdate (1970)

Usage

eelgrass

Format

Tibble with columns

light_treatment

Light treatment: "light" or "dark".

addition_site

The location where 32P phosphate was added: in the "upper" water compartment or in the "lower" water compartment.

compartment

Obsered compartment, one of "leaves_stem", "roots_rhizome", "upper_water", or "lower_water".

time_min

Elapsed time in minutes since the 32P addition.

n_32P_per_mg

Number of 32P atoms per mg (estimated from Figure 2 of the original paper).

mass_mg

Compartment mass in mg (taken from Table 1 of the original paper). Assumed constant during the experiment.

n_32P

Number of 32P atoms in the compartment. Calculated from the two previous columns.

Details

In brief, the experimental setup consists in individual eelgrass plants placed in 250 ml containers. Each container is partitioned by a layer of paraffin into an upper water compartment (containing the leaves and stems) and a lower water compartment (containing the roots and rhizomes).

Radioactive phosphorus (32P) is added as phosphate either in the upper or lower water compartment in each container. Containers were incubated either in light or dark conditions.

Tissue samples were collected and dried at various time points and 32P activity was measured (Figure 2 in the original paper). Biomass estimates in initial conditions were given in Table 1 of the original paper.

Data preparation

The data for 32P abundance per mg is extracted from Figure 2 of the original article. Atom counts per mg were derived from cpm per mg using a half-life value of 14.268 days for 32P.

For simplicity and in order to be able to match the 32P data with the biomass data (see below), only four compartments are considerd in the package dataset. Upper and lower water compartments match the compartments from the original article. "Leaf and stem" pools the original compartments "leaf tip", "leaf middle", "leaf base", and "stem". "Roots and rhizome" pools the original compartments "root" and "rhizome". Pooling is done by averaging the cpm per mg data, thereby making the rough approximation that each component of the pool contributes the same biomass as the other components.

The biomass data is taken from Table 1 in the original paper. Experimental containers had 160 cc of seawater in the upper compartment and 80 cc of seawater in the lower compartment. Based on comparison with data from Risgaard-Petersen 1998, I assumed that the biomasses for tissues were given in dry weight. I assumed that this was also the case for the cpm/mg data (i.e. cpm/mg of dry weight).

Source

Data was taken from the figures and tables of the original paper. The original paper is: McRoy, C. Peter, and Robert J. Barsdate. “Phosphate Absorption in Eelgrass1.” Limnology and Oceanography 15, no. 1 (January 1, 1970): 6–13. https://doi.org/10.4319/lo.1970.15.1.0006.