Titled: Hooked on fish blood: the reliance of a gill parasite on haematophagy

Abstract:
Parasitism exhibits diverse evolutionary strategies, one of which involves adaptations for feeding on blood, a rich source of nutrients to support parasite growth and reproduction. This lifestyle requires unique adaptions for the attachment and extraction of the host’s blood, but also for the use of this tissue as the only nutritional source. <i>Sparicotyle chrysophrii</i> (Polyopisthocotyla, Microcotylidae) is an ectoparasitic flatworm infecting the gills of gilthead seabream (<i>Sparus aurata</i>), an emblematic species in Mediterranean aquaculture. Despite the substantial impact of this parasite on fish health and welfare and on net pen-based farms' profitability, scarce information is available regarding its feeding behaviour. In this study, we demonstrate the presence of blood and exogenous haem groups in <i>S. chrysophrii</i> and delve into the parasite’s digestive tract by light and electron microscopy, elucidating its internal morphology and spatial arrangement. The elemental composition of the digestive haematin cells was analysed and found to contain residual oxidised haem depots in the form of haematin crystals. Additionally, we estimated the average volume of blood intake and described the impact of the parasite on the hosts’ plasmatic free iron levels, overall demonstrating its reliance on its host blood.  

In this repository you will find the following files:

File1a.csv: 
Raw data used to calculate the Fluorescent polymer microspheres - Erythrocyte (FPMs·RBCs^-1) coefficients (Figure 3A). 
VARIABLES: nofi: Fish number; hpi: hours post-injection; mf: Circulating fluorescent polymer microspheres in <i>Sparus aurata</i> bloodstream (FPMs·mL^-1); rbc: Circulating erythrocytes in <i>Sparus aurata</i> bloodstream (RBCs·mL^-1)

File1b.csv: 
Raw data used to calculate the blood intake (uL·18h^-1) (Figure 3B).
VARIABLES: nofi: Fish number; bint: Volumen of blood intake (uL·18h^-1)
**NOTE: Every row entry correspond to a single adult <i>Sparicotyle chrysophrii</i> specimen

GLM_BF.xlsx:
Raw data used to calculate the free plasmatic ionic iron in <i>Sparus aurata</i> (Figure 8) and the correlation with <i> S. chrysophrii </i> infection intensity following the available R script.

R script. R:
R script to analyse the correlation between free plasmatic iron and <i> S. chrysophrii</i> infection intensity