Influence of a Trematode Parasite (Microphallus turgidus) on Grass Shrimp (Palaemonetes pugio) Response to Refuge and Predator Presence

Abstract

The grass shrimp ( Palaemonetes pugio ) is a staple prey species in the diet of many ecologically and economically important species such as blue crab and striped bass and is commonly infected with a trematode parasite, Microphallus turgidus. To complete its life cycle, M. turgidus must be consumed as a metacercaria by a bird or mammal definitive host. Previous research has found that infected grass shrimp behave more conspicuously than uninfected shrimp around predators, which include mummichogs ( Fundulus heteroclitus ). In addition, grass shrimp are more likely to avoid predation when they have access to coarse woody debris (CWD). Aquaria experiments revealed that uninfected shrimp significantly reduce the amount of time spent swimming in the presence of a fish predator, whereas infected shrimp did not exhibit this predation avoidance behavior. Uninfected shrimp also increased predator avoidance behavior ("backthrusts") in the absence of CWD, whereas infected shrimp did not. These findings suggest that M. turgidus does not influence grass shrimp usage of CWD, but it alters shrimp swimming and backthrust behavior, thereby rendering infected shrimp more susceptible to predation. The implications of increased predation by a fish (nonhost or possible paratenic host) versus by a bird or mammal (definitive host) for parasite transmission are discussed.

Missing link: California rock crabs serve as intermediate hosts for the parasite Helicometrina nimia

“…The 28S sequence from metacercariae retrieved from C. productus returned a closest match to Helicometrina nimia (ex Haemulon falvolineatum , French grunt, Mexico) with 97.97% identity (MK648305; see Pérez-Ponce de León & Hernández-Mena, 2019). The 18S sequence from metacercariae retrieved from C. productus returned a closest match with H. nimia , with 98.93% (KJ995999, ex Acanthistius pictus , brick sea bass, Chile; see Gonzalez, 2016). The 18 s sequence from R. antennarium also returned a closest match with H. nimia , with 98.64% (KY614306, ex Semicossyphus darwini , Galapagos sheephead wrasse, Chile; see Ñacari et al ., 2018).…”

“…Paragonimus cf. westermani alters the behaviour of its decapod host ( Eriocheir japonica ) (Kotsyuba, 2018), Microphallus turgidus alters the swimming behaviour of Grass shrimp ( Palaemonetes pugio ) (Gonzalez, 2016) and co-infection by the trematode Maritrema sp. and acanthocephalans in the body cavity of shore crabs has been correlated with altered serotonin levels (Poulin et al ., 2003).…”

Effects of Cymatocarpus solearis (Trematoda: Brachycoeliidae) on its second intermediate host, the Caribbean spiny lobster Panulirus argus

“…In the grass shrimp Palaemonetes pugio , metacercariae of the microphallid Microphallus turgidus encyst mainly in the abdominal muscles, and although swimming of the shrimp can be severely affected, this effect is also independent of the intensity of infection [ 29 ]. Infected shrimp spend less time quiescent, more time outside their shelters, and have a shorter delay to first movement after disturbance, making them more easily identifiable by visual predators [ 31 ]. In contrast, none of the seven components of the escape response of lobsters varied with grade of infection by C .…”

“…argus remained to be determined. In crustacean hosts, parasites may affect the nutritional condition, blood chemistry, or concentration of hemocytes in the hemolymph [ 28 ], the escape response [ 29 – 31 ], or the concentration of certain biogenic amines (neurotransmitters, neuromodulators, and neurohormones), causing behavioral changes that may increase their vulnerability to predators [ 6 , 32 ]. Therefore, in species of commercial value, such as spiny lobsters, parasites may indirectly affect the fisheries if infected lobsters are more susceptible to predation [ 11 ].…”

Long-term change in the parasite burden of shore crabs ( Hemigrapsus oregonensis and Hemigrapsus nudus ) on the northwestern Pacific coast of North America

“…In other regions, infection by microphallid trematodes can alter the behaviour of crustacean intermediate hosts in ways that facilitate trophic transmission to the parasite's final hosts. For example, infection by the microphallid trematode Microphallus turgidus causes grass shrimp intermediate hosts to cease predator avoidance behaviour [43]. If a similar behavioural effect of infection is at play in our host-parasite system, it could mean that H. oregonensis and H. nudus prey are more available for bird predators today than they were in the mid-twentieth century.…”