Variation in the development of two isolates of Cryptocaryon irritans

Two isolates of Cryptocaryon irritans obtained from Acanthopagrus australis from Moreton Bay (isolate C1) and Gymnocranius audleyi from Heron Island (isolate C2) were passaged on Lates calcarifer and Macquaria novemaculeata at 20 and 25 C under identical laboratory conditions. There were significant differences between isolates in the diameter of trophonts and tomonts, the incubation period of tomonts, and the length of theronts. Trophonts of C1 were significantly larger on L. calcarifer than on M. novemaculeata and showed marked size variation with temperature, whereas trophonts of C2 developed equally well on both species and showed little size variation with temperature. Tomonts of C1 were significantly larger than those of C2 when grown on L. calcarifer, whereas on M. novemaculeata tomonts from C1 were significantly smaller than C2 tomonts. The incubation period of tomonts from C1 was significantly shorter than that for tomonts of C2, and theronts of C1 were significantly larger than theronts of C2 under all host/temperature conditions. The differences in the development of these isolates are of biological and epidemiological importance. This indicates that distinct intraspecific variants of C. irritans occur along the coast of southeast Queensland

The rate of development of Polylabroides multispinosus (Monogenea: Microcotylidae) parasitic on the gills of Acanthopagrus australis (Pisces: Sparidae)

Experiments were done to determine the rate of development of Polylabroides multispinosus. Eggs hatch after an average 9,7 and 6 days at 20,24 and 28°C, respectively. The ciliated oncomiracidium hatched with one pair of clamps (c.p.). Juvenile worms less than 3 days post-infection (p.i.) had 2 c.p. and blood and hematin in the simple, saccular gut. The gut bifurcated at 11 c.p. (6-9 days p.i.) (24°C). The genital atrium, testes, ovary and vitellaria appeared at 16 c.p. (8-11 days p.i.), 22 c.p. (10-14 days p.i.), 30 c.p. (14-18 days p.i.) and 40 c.p. (17-21 days p.i.), respectively. Eggs were produced at 20 days p.i. The period from egg deposition to egg deposition is about one month at 24°C

The influence of formalin, benzocaine and hyposalinity on the fecundity and viability of Polylabroides multispinosus (Monogenea: Microcotylidae) parasitic on the gills of Acanthopagrus australis (Pisces: Sparidae)

Adult Polylabroides multispinosus exposed in vivo to formalin (200 p.p.m. in sea water, 30 min) deposited a similar number of eggs in 24 h in vitro as did control parasites (sea water, 35 parts per thousand, p.p.t., salinity) and worms exposed in vivo to benzocaine (40 p.p.m. in sea water, 10 min). Worms laid more eggs at 30 p.p.t. salinity in vitro than at 20, 35, 10 and 5 p.p.t. salinity (in decreasing order). Formalin (200 p.p.m., 30 min) decreased the viability of recently laid eggs, the survival of oncomiracidia, removed 70% of juvenile and adult worms from the gills, but decreased only slightly the viability of eggs exposed in utero or after eyespots developed in vitro. Salinities below 30 p.p.t. reduced viability as did an increase in temperature from 24 to 28°C. All adult and juvenile worms were removed by baths in formalin (400 p.p.m., 25 min) or fresh water (l h)

Efficacy of Aqui-S, Formalin and Praziquantel Against the Monogeneans, \u3ci\u3eBenedenia seriolae\u3c/i\u3e and \u3ci\u3eZeuxapta seriolae\u3c/i\u3e, Infecting Yellowtail Kingfish \u3ci\u3eSeriola lalandi lalandi\u3c/i\u3e in New Zealand

This study assessed the efficacy of bath administrations of Aqui-S, formalin and praziquantel against adults and eggs of Benedenia seriolae and Zeuxapta seriolae, two monogenean ectoparasites of kingfish (Seriola lalandi lalandi). Our results showed that 2.5 ppm praziquantel administered for either 24 or 48 h was the most effective treatment for removing B. seriolae (\u3e99%). However, B. seriolae treated with praziquantel for 24 h deposited viable eggs. Formalin at 250 and 400 ppm for 1 h followed by a 5 min freshwater dip was less effective for removing B. seriolae (ca. 80%), but both treatments inhibited the production of eggs by treated parasites. However, a large proportion of B. seriolae eggs exposed to either formalin treatment remained viable. Praziquantel (2.5 ppm for either 24 or 48 h) and formalin (400 ppm for 1 h+5 min f/w dip) were the most effective treatments for removing Z. seriolae from the gills of kingfish (\u3e99%) but the parasites thus removed continued to deposit viable eggs. Exposure to the anaesthetic Aqui-S did not significantly increase numbers of B. seriolae or Z. seriolae removed from the host above those of the control, but it was ineffective in preventing the production of eggs by treated parasites, and did not reduce egg viability. Eggs of B. seriolae were not prevented from hatching unless exposed to air for a period greater than 3 h, and Z. seriolae eggs were only prevented from hatching if exposed to air for periods greater than 5 h prior to the development of eyespots. These results indicate that both primary and secondary treatments will be required to successfully control B. seriolae and Z. seriolae infections in captive kingfish

Problems with equating thermal preference with ‘emotional fever’ and sentience: comment on ‘Fish can show emotional fever: stress-induced hyperthermia in zebrafish’ by Rey et al

publishedVersio

Problems with equating thermal preference with ‘emotional fever’ and sentience: Comment on ‘fish can show emotional fever: Stress-induced hyperthermia in zebrafish’ by rey et al. (2015)

publishedVersio

The bacterial storage compound poly-β-hydroxybutyrate protects Artemia franciscana from pathogenic Vibrio campbellii

Infections caused by antibiotic-resistant luminescent Vibrios can cause dramatic losses in aquaculture. In this study, the short-chain fatty acid β-hydroxybutyrate and its polymer poly-β-hydroxybutyrate were investigated as possible new biocontrol agents. β-Hydroxybutyrate was shown to completely inhibit the growth of pathogenic Vibrio campbelli at 100 mM. Moreover, the addition of 100 mM of this fatty acid to the culture water of Artemia nauplii infected with the V. campbelli strain significantly increased the survival of the nauplii. As Artemia is a non-selective and particle filter feeder, we also investigated whether poly-β-hydroxybutyrate particles could be used to protect Artemia from the pathogenic V. campbellii. The addition of 100 mg l−1 poly-β-hydroxybutyrate or more to the Artemia culture water offered a preventive and curative protection from the pathogen as a significantly enhanced survival was noticed. If added as a preventive treatment, a complete protection of infected nauplii (no significant mortality compared with uninfected nauplii) was observed at 1000 mg l−1 poly-β-hydroxybutyrate. Our data indicate that the use of poly-β-hydroxybutyrate might constitute an ecologically and economically sustainable alternative strategy to fight infections in aquaculture

Vibrio harveyi: a significant pathogen of marine vertebrates and invertebrates

Vibrio harveyi, which now includes Vibrio carchariae as a junior synonym, is a serious pathogen of marine fish and invertebrates, particularly penaeid shrimp. In fish, the diseases include vasculitis, gastro-enteritis and eye lesions. With shrimp, the pathogen is associated with luminous vibriosis and Bolitas negricans. Yet, the pathogenicity mechanisms are imprecisely understood, with likely mechanisms involving the ability to attach and form biofilms, quorum sensing, various extracellular products including proteases and haemolysins, lipopolysaccharide, and interaction with bacteriophage and bacteriocin-like substances