Mycobacteriosis in wild rabbitfish Siganus rivulatus associated with cage farming in the Gulf of Eilat, Red Sea

Abstract

Infection patterns of Mycobacterium rnarinum were studied over a period of 3 yr in wild rabbitfish Siganus rivulatus populations associated with commercial mariculture cages and inhabiting various sites along the Israeli Red Sea coastline. Mycobacteriosis was first recorded from the Red Sea in 1990 in farmed sea bass Dicentrarchus labrax and is absent from records of studies on parasites and diseases of wild rabbitfish carned out in the 1970s and 1980s. A sharp increase in the prevalence of the dsease in cultured and wild fish in the region has occurred since. A total of 1142 rabbitfish were examined over a 3 yr period from inside mariculture net cages, from the cage surroundings and from several sites along the coast. Histological sections of spleens were examined for presence of granulomatous lesions. Overall prevalence levels of 50 % were recorded in the rabbitfish sampled inside the net cages and 39 % at the cages' close surroundings, 21 % at a sandy beach site 1.2 km westwards, 35 % at Eilat harbour 3 km to the south and 4 2 % at a coral reef site about 10 km south of the cages. In addition, 147 fish belonging to 18 native Red Sea species were sampled from 2 sites, the net cage farm perimeter and the coral reef area, and examined for similar lesions. None of those from the coral reef were infected with Mycobacterium; however, 9 of 14 species collected from the cage surroundings were infected. An increase in prevalence of mycobacteriosis in the manculture farm area was noted from 1995 to 1997. At the same time, a significant increase in prevalence was also apparent at the coral reef sampling site. Two M. marinum isolates from rabbitfish captured at Eilat harbour and the coral reef site were shown by 16s rDNA sequencing analysis to be identical to isolates from rabbitfish trapped inside the mariculture cages as well as isolates from locally cultured sea bass D. labrax. The implications of spreading of M, marinum infection in wild fish populations in the Gulf of Eilat are discussed.

Globally Distributed Mycobacterial Fish Pathogens Produce a Novel Plasmid-Encoded Toxic Macrolide, Mycolactone F

“…1). The Israeli marine strain was first isolated from cultured sea bass (Dicentrarchus labrax), but many Red Sea species appear to be susceptible to infection (5,8,33).Newly emerging mycobacterial fish pathogens from the Chesapeake Bay in the United States have also been reported (15,25). In 2005 a new mycobacterial species, Mycobacterium pseudoshottsii, was described in association with epizootic fish disease among striped bass (Morone saxatilis) in the Chesapeake Bay, Maryland.…”

“…1). The Israeli marine strain was first isolated from cultured sea bass (Dicentrarchus labrax), but many Red Sea species appear to be susceptible to infection (5,8,33).…”

Transmission through the water of the bacterial diseases of the euryaline fish cultured in the Mediterranean. Elements of epidemiology and risk factors which concern their spread and transmission of the respective pathogens

“…Προσβάλλονται πάνω από 150 είδη ψαριών, στα οποία προκαλείται χρόνια νόσος που παραμένει ασυμπτωματική για μεγάλο διάστημα (Toranzo et al 2005). Είδη του γένουςMycobacterium μπορούν να ε πιζήσουν μέσα στο νερό και στον πυθμένα της θά λασσας έως και 2 χρόνια (Reichenbach-Klinke 1972), ενώ η μετάδοση τους με το νερό έχει δειχθεί σε επι δημιολογικές μελέτες (Diamant et al 2000;Korun et al 2005).…”

MARS: biological indicators of natural and man-made changes in marine and coastal waters: scientific coordinators' introduction

“…Observations and field data collected over the years indicate an increase in breakage of reef-building coral branches, decline in coral species diversity and recruitment rates and overall number of live coral colonies in Eilat's nature reserve (Zakai and Chadwick-Furman 2002). There is an increased incidence of diseased coral (Sussman et al 2003) and fish, shown to be linked with anthropogenic activity (Diamant et al 2000;Diamant 2001;Colorni et al 2002).…”