Assessing the effects of water flow rate on parasite transmission amongst a social host

Abstract

Many freshwater habitats are subject to change through time. Specifically, natural flow regimes are substantially modified by not only seasonal climatic change, but also anthropogenic activity. Consequently, freshwater organisms are exposed to variable flow, potentially altering their behaviour and subsequently parasite transmission amongst social hosts. Here, we investigate the effects of flow conditions on the shoaling behaviour of Trinidadian guppies (Poecilia reticulata), and the resulting transmission of a directly transmitted ectoparasite, Gyrodactylus turnbulli. Shoals exposed to continuous flow exhibited significantly greater G. turnbulli peak intensities and abundance when compared to fish subjected to interrupted, but not no-flow conditions. Parasite transmission rate was greater in shoals exposed to interrupted flow, resulting in parasites becoming more distributed amongst shoal members and thus reducing mean intensity in comparison to continuous flow shoals. Furthermore, as prevalence increased, the distance between shoaling conspecifics increased at greater rates in interrupted and no-flow conditions compared to continuous flow: indicating that in the absence of flowing water, parasitism has a greater effect on shoaling decisions. This data highlights how fish behaviourally respond to variable flow conditions and the implications for parasite transmission.

Effect of Poultry Litter as an Organic Fertilizer, in Water Quality, Parasitic Abundance, and Growth Nile Tilapia

“…In this context, the parasite transmission form is essential for its establishment and success, and characteristics such as a monoxenous life cycle and fish density in the aquaculture system favor the establishment and predominance of the monogeneans, being the most relevant parasite in fish farming (Jerônimo et al, 2011). In the production system, a decrease in water quality, excessive handling, and nutritional deficiency result in a stress condition for fish, which consequently impairs the immunological system and makes fish prone to disease outbreaks (Lanes et al, 2012;Reynolds et al, 2019). In general, monogeneans infestations in the gills can cause lamellar hyperplasia and difficulty in gas exchange, leaving the host more vulnerable to severe mixed infections (fungi, bacteria, and parasites) affecting growth and can lead to death (Dezfuli et al, 2007;Pádua et al, 2016).…”

Responses of monogenean species to variations in abiotic parameters in tilapiculture

“…The abundance of monogenean species reported in this study varied according to the changes in the physical and chemical water parameters during the culture cycle. This corroborates the findings of previous studies showing that the population abundance of Cichlidogyrus is related to seasonal variations as well as chemical and organic pollution (Madanire-Moyo et al ., 2011; Vidal-Martínez & Wunderlich, 2017; Reynolds et al ., 2019).…”

Transmission dynamics of ectoparasitic gyrodactylids (Platyhelminthes, Monogenea): An integrative review

“…In this experiment, a 12 h flow: 12 h no flow comprised the interrupted flow regime, and during flow, guppies aggregated in a refuge wherein flow was minimal (Reynolds et al ., 2019). Therefore, in interrupted flow conditions there was a higher likelihood of more direct contacts between hosts, and perhaps because guppies appear unable to discriminate olfactory cues between infected and uninfected conspecifics in these flow regimes, they were unable to avoid the elevated transmission risk (Reynolds et al ., 2019). This aggregation behaviour occurs in natural habitats with high predation regimes during the night (Seghers, 1974; Croft et al ., 2003).…”

“…resting conspecifics attempting to offload their parasite burdens (Reynolds et al, 2019). Still, so far, the effect of light conditions on worm activity has been tested only in G. gasterostei and G. arcuatus (Brooker et al, 2011).…”

“…Water flow regime is further likely important. Shoals of P. reticulata exposed to interrupted flow exhibited greater mean transmission rates of G. turnbulli compared to continuous and non-flow conditions (Reynolds et al ., 2019). In this experiment, a 12 h flow: 12 h no flow comprised the interrupted flow regime, and during flow, guppies aggregated in a refuge wherein flow was minimal (Reynolds et al ., 2019).…”