Infections of Cryptocaryon irritans on wild fish from southeast Queensland, Australia

Abstract

Wild-caught marine fish from 3 sites in SE Queensland, Australia, were examined over a period of up to 13 mo for infections of the parasitic ciliate Cryptocaryon irritans. Infections of C. irritans were found to be common on the fish sampled. Out of a total of 358 fish (14 species), 239 (66.7%) from 13 species were found to be infected. At Site 1 at the mouth of an estuary, the prevalence of C. irritans infections was 79% and the mean intensity was 12.9 parasites fish-'. At Site 2, a coastal bar area, the prevalence of infection dropped to 66 % and a mean intensity of 5.0 parasites fish-', whilst at Site 3 on the Great Barrier Reef, prevalence was lowest at 51 % with a mean intensity of 2.3 parasites fish-' The study concentrated on 2 sparid fishes, Acanthopagrus australis from Sites 1 and 2 and Gymnocranius audleyi from Site 3. The prevalence of infections on A. australis from Site 1 (n = 101) was 100% with a mean intensity of 14.6 parasites fish-', whilst at Site 2 (n = 74) the prevalence was 88 % at a mean intensity of 5.2 parasites fish-'. There was no apparent seasonality In prevalence or intensity of infections at Sites 1 and 2 despite water temperatures ranging between 15 and 27°C. At Site 3, the prevalence of infections of G. audleyi (n = 39) was 38% with a mean intensity of 1.9 parasites fish-'. The diameter of the tomonts collected from A. australis from Sites 1 and 2 vaned inversely with water temperature, and was not related to host size. Our results show that infections of C vntans are common on wild fish, not rare as previously thought. This may be partially due to the increased sensitivity of our tomont collection technique. Our data suggest that C. irritansmay exhibit a degree of host specificity in the wild, and also that its natural distribution can be extended into estuaries and seasonally into warm temperate waters.

A new strain of Cryptocaryon irritans from the cultured olive flounder Paralichthys olivaceus

“…Although the size of the present ciliates in all life stages was larger than that reported for C. irritans (Brown 1963, Nigrelli & Ruggieri 1966, Cheung et al 1981, Colorni 1987, Colorni & Diamant 1993, there were no differences in morphological features. It seems that the fact that present ciliates were larger than the typical C. irritans resulted from lower ambient temperatures, which was also pointed out by Diggles & Lester (1996b). There are numerous reports on the reproduction pattern of Cryptocaryon irritans (Brown 1963, Nigrelli & Ruggieri 1966, Cheung et al 1980, Colorni 1987, Colorni & Diamant 1993.…”

“…The trophonts released from the infected juveniles showed reproductive patterns identical to those mentioned above. Diggles & Lester (1996b) reported that the heaviest infection of Cryptocaryon irritans on Acanthopagrus austrails occurred at 17°C and infections were still recorded at 15°C, a temperature at which C. irritans infections were found not to occur in previous studies (Wilkie & Gordin 1969). This suggested the possible existence of different strains of C. irritanse which can be differentiated by their temperature tolerance.…”

Characterization of Cryptocaryon irritans, a parasite isolated from marine fishes in Taiwan

“…This is the first record of outbreak of C. irritans at such a low recorded salinity in aquaculture conditions. Diggles & Adlard (1997), however, cited an unpublished report related to survival of tomonts below 10 ppt, and Diggles & Lester (1996a) suggested an extended distribution of C. irritans in estuaries. The successful adaptation and continuous propagation of the Kaoshiung isolate at 10 ppt further attests to the need for immediate attention to outbreaks of the parasite at low salinity.…”

“…Recently, the parasite was taxonomically reassigned to the order Prorodontida within the class Prostomatea, and a new family name was recommended, Cryptocaryonidae (Wright & Colorni 2002). Diverse wild fish and coral reef species are affected by the disease, which sometimes results in mortality (Bunkley-Williams & Williams 1994, Diggles & Lester 1996a. Horizontal transfer, dispersal and development of the parasite in coral reefs are facilitated through the low level of hostspecificity of C. irritans (Burgess & Matthews 1995) and the presence of various fish species.…”

“…Diamant et al (1991) reported mortality of gilt-head sea bream Sparus aurata broodstock due to infection by a Cryptocaryon-like ciliate (distinct from C. irritans) on the Mediterranean coast at an ambient temperature of 22°C. Variants or strains of C. irritans have also been recognised, based on various parameters (Diggles & Lester 1996a,b,c, Diggles & Adlard 1997, Jee et al 2000.…”