DOI: 10.5061/dryad.z08kprrdh
title: Host energetics explain variation in parasite productivity across hosts and ecosystems

description: Parasites are thought to play a role in ecosystem energetics, in part
 because some ecosystems harbor a substantial amount of parasite biomass.
 Nevertheless, the extent to which parasite biomass accurately reflects the
 flow of energy from hosts to parasites, and the linkages between their
 energetics, remain unclear. Here, we estimate parasite community
 energetics at the host and ecosystem-level and test predictions for
 parasite energetics using the metabolic theory of ecology. Across 27 host
 species, parasite community abundance declines with average individual
 parasite energy use Rp as Rp-0.50 and increases with host metabolic rate
 Rh as Rh 0.63, which is inconsistent with metabolic theory. We next test
 whether the fraction of host energy that is allocated to parasitism is
 invariant across hosts. Our empirical analysis demonstrates that 85% of
 the variation in parasite community energy use can be explained by
 differences in host metabolic rate. However, parasite community energy use
 increases allometrically with host metabolic rate   as
   suggesting that the fraction of host energy used by
 parasites declines with host metabolic rate. At the ecosystem-level, we
 show that the energy flowing through parasite communities scales
 allometrically with the total rate of energy use by their fish hosts
 across three ecosystems. Importantly, directly examining energy flux
 revealed variation in parasite energy use among ecosystems that was not
 apparent when examining differences in biomass. Taken together, these
 results establish strong empirical links between host and parasite
 energetics, but our findings often did not align with predictions based on
 metabolic theory.
description: ReadMe.txt file for data deposited for:<br> Host energetics
 explain variation in parasite productivity across hosts and
 ecosystems Four datasets are providing as .csv
 files. Data S1.
 'DataS1.parasite_community_abundance_data'<br> This is a
 .csv file containing data pertaining to Figure 1.<br> In Figure 1
 plotted are the partial residuals of the linear model: np ~ avg_alpha +
 mh_alph_no_temp<br> Note. Data S1 is filtered by absolute maximum
 community abundance; see Table S2 for comparison of model coeffs.
   Data S2.
 'DataS2.parasite_community_flux_data'<br> This is a .csv
 file containing data pertaining to Figure 2.<br> In Figure 2 plotted
 is parasite_flux ~ mh_alpha<br> Note. Data S2 is filtered by
 absolute maximum community flux; see Table S3 for comparison of model
 coeffs.    Metadata for Data files S1 and S2:<br>
 Column_headers. host_species: genus and species of host
 taxa<br> code: unique identifier of host individual used in the
 analysis<br> parasite_flux:  unit watts; temperature corrected
 parasite community flux following equation 6 in the main text; parasite
 flux = [(a*parasite body mass (kg) ^b)*
 exp((E_parasite/0.0000862)*(-((Temp_O+273.15)^-1) + ((Temp+273.15)^-1))))]
 * parasite abundance) and summed across all parasite species, where a =
 phylum specific normalization constant from table 1 in maint text and b =
 phylum specific scaling exponenet from table 1.  <br> mh_alpha: unit
 watts; temperature corrected host metabolic rate following equation 5 in
 the maint text; host metabolic rate = (a * host body mass (kg) ^ b) *
 exp((E_host/0.0000862)*(-((Temp_O+273.15)^-1) +
 ((Temp+273.15)^-1))))<br> mh_alpha_no_temp: unit watts; host
 metabolic rate following equation 5 in the maint text; host metabolic rate
 = (a * host body mass (kg) ^ b)<br> mh: units grams; host body
 mass<br> np: total parasite abundance, which is all parasite
 individuals within a host<br> n: number of hosts dissected; using a
 min. of 15 individuals per host species<br> avg_alpha: unit watts;
 mean energy usage within a parasite community see main text for
 calculation (note this is not temp corrected)<br> host_taxon: host
 taxonomic group, pertains to metabolic scaling parameters in table
 1<br> Temp_O: units celsius; environmental temperature during
 collection period (notes needs to transforemd to kelvin for temperature
 correction)<br> Data_source: where the data came from, new data=
 unpublished data first used in this manuscript Data S3.
 'DataS3.energy_flux_ecosystem'<br> This is a .csv file
 containing data pertaining to figure 3.<br> In Figure 3A plotted are
 log_parasite_flux ~ log _host_flux + river<br> In Figure 3B plotted
 are log_parasite_biomass ~ log_host_biomass +river
 Metadata for Data file S3.:<br> Column_headers.
 river: name of river ecosystem; Passaic, Raritan,
 Mullica<br> season: seaon fall, winter, spring, summer<br>
 plot: site within river ecosystem<br> log_parasite_flux: units
 watts/m^2; log10 transformed parasite community flux within a
 sample<br> log_host_flux: units watts/m^2; log10 transformed host
 community flux within a sample<br> log_parasite_biomass: units
 g/m^2; log10 transformed parasite biomass density within a
 sample<br> log_host_biomass: units g/m^2; log10 transformed host
 biomass density within a sample Data S4.
 'DataS4.platyhelminthes_scaling'<br> This is a .csv file
 containing data used to estimate platyhelminthe metabolic scaling
 parameters given in Table 1, further details are provided in Supplmental
 materials Appendix II. Metadata for Data file
 S4:<br> Column_headers. species: parasite
 species; genus species<br> stage: parasite lifecycle stage; adult,
 larvae, sporocyst, redia<br> Temperature C: temperature at which
 metabolic rate was taken in degrees celsius<br> Body mass in
 original units: body mass of parasite in orignal units from
 study<br> Mass original units: units of mass  in study<br>
 Mean Respiration Rate in original units: metabolic rate in orignal units
 from study<br> respiration_units: units of metabolic rate in
 study<br> Notes on conversion: all conversions used<br>
 ln(body mass) (kg): units kg; natural log transformed body mass in wet
 weight<br> ln(metabolic rate) (Watts): units watts;  natural log
 transformed metabolic rate<br> Source: citation of study<br>
 Host type: host used in the study given as genus
 species/'free-living' indicates free living larval stage
 used