Effect of trematode parasites on cockle Cerastoderma edule growth and condition index: a transplant experiment

Abstract

We quantified the effect of trematode parasites in cockles through a 303 d transplant experiment. Cockles were sampled in 3 different sites on the southwest coast of France characterized by 3 different trematode communities, i.e. Royan (RO): high Meiogymnophallus minutus abundance near cockle heart, South Arguin (SA): high Himasthla interrupta abundance in the mantle margin, and North Arguin (NA): almost free of trematodes. Sampled cockles were individually tagged and placed in different cages at Banc d'Arguin, Arcachon Bay. At the end of the experiment, RO cockles had lost their trematodes, highlighting the fact that trematode lifespan can be short, while SA cockles maintained their trematode load. When cockles were the second intermediate host, there was no effect of site of origin on cockle condition index and survival. The effect on growth rate was mostly due to initial cockle length. Within each treatment, the only significant effect of trematode infection on growth was found for H. interrupta at SA. The 23% growth deficit observed could be due to the disruption of cockle shell synthesis in the mantle margin. During the transplant experiment, cockles were also infected at an exceptionally high rate by Bucephalus minimus, a trematode which invades most of the tissues and uses the cockle as a first intermediate host. Surprisingly, there was an effect on the growth rate and condition index of cockles at only one of the sites under study. This field experiment succeeded in quantifying the moderately negative effect of trematode parasites on the growth and condition of their host and suggested the existence of interactions with as yet unknown factors. KEY WORDS: Cerastoderma edule · Parasitism · Growth · Mortality · Condition index · Transplant experiment Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 471: [111][112][113][114][115][116][117][118][119][120][121] 2012 Cerastoderma edule. A recent census listed 16 species associated with trematodes, from Norway to South Morocco, including the British Isles (de ). In the first intermediate host, the parasite reproduces asexually and invades most host tissues, resulting in dramatic effects such as castration or death. This is the sporocyst or rediae stage, leading to the emission in the water body of thousands of new parasite propagules called cercariae. The parasite prevalence at this stage (i.e. percentage of infected hosts) is generally low, and the effect at the population scale is small. However, under certain environmental conditions (often remaining unidentified), prevalence reaches dramatically high values and is correlated with mass mortality (Jonsson & André 1992). Cercariae that are shed by the first intermediate host have only a few hours to infect the second intermediate host and to settle as a latent stage called the metacercariae. The effect on these second intermediate hosts seems less deleterious, since metacercariae do not reproduce in the host tissues: they wait for their host to be pred...

Can host density attenuate parasitism?

“…Although it is necessary to increase knowledge in terms of the real effect of metacercariae on hosts' fitness, it has been now established that high metacercariae numbers induce reductions in growth, condition index and burying capacity (e.g. Babirat et al ., 2004; de Montaudouin et al ., 2012; O'Connell-Milne et al ., 2016) and are correlated with higher mortality rates, namely for trematode species that were observed in this study, i.e. C. arguinae (Desclaux et al ., 2006), H. interrupta (de Montaudouin et al ., 2012), H. quissetensis (Desclaux et al ., 2004) and Parvatrema minutum (Gam et al ., 2009).…”

“…Generally, metacercariae infection displays high prevalence but, under standard environmental conditions, the pathogenicity is reported as low, with little interaction between parasite and host (e.g. Wegeberg & Jensen, 1999; de Montaudouin et al ., 2012). Occasionally, metacercariae abundance can reach relatively high values, disrupting bivalve basic functions such as growth (de Montaudouin et al ., 2012), burying capacity (Babirat et al ., 2004) or even causing mortality (Desclaux et al ., 2002, 2004; Gam et al ., 2009).…”

“…Wegeberg & Jensen, 1999; de Montaudouin et al ., 2012). Occasionally, metacercariae abundance can reach relatively high values, disrupting bivalve basic functions such as growth (de Montaudouin et al ., 2012), burying capacity (Babirat et al ., 2004) or even causing mortality (Desclaux et al ., 2002, 2004; Gam et al ., 2009). For these reasons, it is important to recognize processes that can enhance metacercariae abundance leading to disease risk.…”

Assessment of the Lipid Composition and Some Components of the Antioxidant System in Blue Mussels Mytilus Edulis Experimentally Infected With Himasthla Elongata Metacercariae

“…Исследования взаимодействий в систе-ме «паразит -хозяин» на примере различных видов трематод и двустворчатых моллюсков проводились начиная с 1960-х годов [Cheng, 1967;Lauckner, 1983;De Montaudouin et al, 2012]. Среди многообразия аспектов во взаи-моотношениях «паразит -хозяин» актуальным остается вопрос о влиянии паразитов на био-химический статус хозяина.…”

Bacciger bacciger (Trematoda: Fellodistomidae) infection effects on wedge clam Donax trunculus condition

“…After escaping from sporocysts parasitizing the bivalves' first intermediate host (presumably D. trunculus in the present study), cercariae penetrate and encyst as metacercariae in the amphipod Ericthonius difformis MilneEdwards, 1830 that may be eaten by fish (Atherina L. 1758) where they develop into adults in the digestive tract. As a trematode using D. trunculus as the first intermediate host, with sporocysts intruding into the gonads, visceral mass, and eventually the whole body, it can be assumed by comparison with other bivalves being similarly infected by other trematode species that B. bacciger (Jonsson & André 1992, Thieltges 2006, de Montaudouin et al 2012 will have a detrimental effect on its host. Ramón et al (1999) noted castration in 2.4% of a D. trunculus population in the Gulf of Valencia (Spain).…”