Consumption of monogenean eggs by crustaceans and fish

Abstract

The use of biological agents to control parasitic diseases in aquaculture is becoming increasingly popular as it is considered safe, effective and economically beneficial strategy for sustainable aquaculture practices. Monogeneans are among the most problematic parasites in fish farms. Their local outbreaks are largely attributed to the accumulation of eggs on farming structures, and the removal of these eggs by biological agents can be a novel solution to control monogenean diseases. We assessed the consumption of monogenean eggs by two amphipod species (a gammarid and a caprellid), the grass shrimp Palaemon pacificus and three fish (two monacanthids and Girella punctata). The ingestion of Neobenedenia girellae and/or Heteraxine heterocerca eggs was directly or indirectly confirmed in all of the tested organisms. The eggs ingested by the crustaceans lost viability, while those eaten by fish hatched after excretion. Monacanthid filefish consumed N. girellae eggs at the highest rate, up to more than 23,000 eggs individual‐1 24 hr‐1. A cohabitation of Seriola dumerili with a monacanthid, Rudarius ercodes, showed a lower acquisition of N. girellae than those kept without R. ercodes. The results indicated that these crustaceans and fish can be useful biological agents for removing monogenean eggs from culturing facilities.

A decision support tool for parasite management in fish aquaculture

“…Biocontrols are also being explored as an option to reduce monogenean egg fouling on net pens using shrimp and other crustaceans. [50][51][52][53] Recently, Skilton et al 2 proposed synchronously timed deployment of light traps could be used to exploit positive phototaxis and hatching rhythms of N. girellae oncomiracidia. Indeed, shaded cages lowered N. girellae infections on fish, showing that light manipulation of parasites may be achieved in multiple ways.…”

“…It has also been shown that high infection of N. girellae occurs near the surface, 48 thus ‘snorkel’ cages used in salmon production in Norway to limit interactions near the surface between salmon and sea‐lice 49 may have applicability for the management of monogeneans in Seriola aquaculture. Biocontrols are also being explored as an option to reduce monogenean egg fouling on net pens using shrimp and other crustaceans 50–53 . Recently, Skilton et al 2 proposed synchronously timed deployment of light traps could be used to exploit positive phototaxis and hatching rhythms of N. girellae oncomiracidia.…”