Biological controls to manage Acropora-eating flatworms in coral aquaculture

Abstract

Coral aquaculture is expanding to supply the marine ornamental trade and active coral reef restoration. A common pest of Acropora corals is the Acropora-eating flatworm Prosthiostomum acroporae, which can cause colonial mortality at high infestation densities on Acropora spp. We investigated the potential of 2 biological control organisms in marine aquaria for the control of P. acroporae infestations. A. millepora fragments infested with adult polyclad flatworms (5 flatworms fragment-1) or single egg clusters laid on Acropora skeleton were cohabited with either sixline wrasse Pseudocheilinus hexataenia or the peppermint shrimp Lysmata vittata and compared to a control (i.e. no predator) to assess their ability to consume P. acroporae at different life stages over 24 h. P. hexataenia consumed 100% of adult flatworms from A. millepora fragments (n = 9; 5 flatworms fragment-1), while L. vittata consumed 82.0 ± 26.76% of adult flatworms (mean ± SD; n = 20). Pseudocheilinus hexataenia did not consume any Prosthiostomum acroporae egg capsules, while L. vittata consumed 63.67 ± 43.48% (n = 20) of egg capsules on the Acropora skeletons. Mean handling losses in controls were 5.83% (shrimp system) and 7.50% (fish system) of flatworms and 2.39% (fish system) and 7.50% (shrimp system) of egg capsules. Encounters between L. vittata and P. hexataenia result in predation of P. acroporae on an Acropora coral host and represent viable biological controls for reducing infestations of P. acroporae in aquaculture systems.

Limited Cross-Species Virus Transmission in a Spatially Restricted Coral Reef Fish Community

“…For example, in Australia, dwarf gourami ( Trichipodus lalius ) can transmit infectious kidney and spleen necrosis virus (genus Megalocytivirus, Iridoviridae ) to domestic fishes, often with detrimental impacts including disease outbreaks in iconic species such as Murray cod ( Maccullochella peelii ) [23, 24]. Moreover, tropical wrasses (Labridae) have been considered effective biological control agents in aquaculture for their natural ability to consume pests [25]. However, temperate cleaner wrasses have been reported to be important drivers of outbreaks of viral haemorrhagic septicaemia virus ( Rhabdoviridae ) in farmed salmonids [26].…”

Natural Products in Polyclad Flatworms

“…The most studied cases of predation by polyclads are in relation to the damage they cause to the commercial shellfish industry, and to a lesser extent the coral aquaculture industry [42][43][44][45][46][47]. Globally, shellfish stocks such as oysters (pearl and food), mussels and clams suffer predation by flatworms, with members of the family Stylochoidea typically responsible for the majority of damage [48,49].…”

Parasites and coral‐associated invertebrates that impact coral health

“…The peppermint shrimp Lysmata vittata (Stimpson, 1860) and sixline wrasse Pseudocheilinus hexataenia (Bleeker, 1862) were suggested by Barton et al . (2020) as suitable biological control candidates in captive systems. The authors found L. vittata removed 82.0 ± 26.76% (mean ± SD) of egg capsules laid on Acropora skeleton and 63.67 ± 43.48% of flatworm individuals from Acropora millepora fragments.…”