Environmental Factors Associated with the Presence of Vibrionaceae in Tropical Cage‐Cultured Marine Fishes

Abstract

This study investigated the environmental factors associated with the presence of Vibrionaceae in economically important cage‐cultured tropical marine fishes: the Asian Seabass Lates calcarifer, snapper Lutjanus sp., and hybrid grouper Epinephelus sp. Fish sampling was conducted at monthly intervals between December 2016 and August 2017. The body weight and length of individual fish were measured, and the skin, eye, liver, and kidney were sampled for bacterial isolation and identification. Water physicochemical parameters during the sampling activities were determined, and the enumeration of total Vibrionaceae count was also conducted from water and sediment samples. Nine species of Vibrio were identified, including V. alginolyticus, V. diabolicus, V. harveyi, V. campbellii, V. parahaemolyticus, V. rotiferianus, V. furnissii, V. fluvialis, and V. vulnificus. Photobacterium damselae subsp. damselae was also identified. A total of 73% of the isolated Vibrio belonged to the Harveyi clade, followed by the Vulnificus clade (5.5%) and Cholera clade (0.6%). Highest occurrence of Vibrio spp. and P. damselae subsp. damselae was found in hybrid grouper (72%), followed by Asian Seabass (48%) and snapper (36%). The associations of Vibrio spp. and P. damselae subsp. damselae with the host fish were not species specific. However, fish mortality and fish size showed strong associations with the presence of some Vibrio spp. On average, 60% of the infected cultured fish exhibited at least one clinical sign. Nevertheless, inconsistent associations were observed between the pathogens and water quality. The yearlong occurrence and abundance of Vibrionaceae in the environmental components indicate that they might serve as reservoirs of these pathogens.

Diversity, Relative Abundance, and Functional Genes of Intestinal Microbiota of Tiger Grouper (Epinephelus fuscoguttatus) and Asian Seabass (Lates calcarifer) Reared in A Semi-Closed Hatchery in Dry and Wet Seasons

“…Indeed, Vibrionales dominated the intestinal microbiota of Asian seabass in both seasons, but significantly higher in dry season, as reported in a previous study (Zarkasi et al, 2014). This proved that Vibrio is a normal flora in the fish intestine and marine water, but also possible to cause vibriosis in cultured fish kept in high water temperature of the dry season (Abdullah et al, 2017;Mohamad et al, 2019c). Although there was no vibriosis outbreak in the period of this study period, it was suspected that further increase in the abundance of Vibrio might trigger an outbreak in the hatchery if no precaution was taken.…”

Estimating the Economic Loss Due to Vibriosis in Net-Cage Cultured Asian Seabass (Lates calcarifer): Evidence From the East Coast of Peninsular Malaysia

“…Animal diseases can affect the aquaculture production function by destroying basic resources, reducing the physical output or unit value of a production process, lowering the efficiency of a production process, and directly affect human well-being (8,9); this can ultimately lead to economic losses in the aquaculture sector. Several viral, fungal, parasitic, and bacterial diseases have been reported to affect cage-cultured Asian seabass, which can further cause co-infections (10,11). In Malaysia, brackish water aquaculture includes the production of Asian seabass, which accounted for 290,900 metric tons in 2018; however, it was a 10.3% decrease from its previous year's production (12).…”

“…One of the primary factors leading to the fall in production has been attributed to the occurrence of infectious diseases (13). In this context, we focus on vibriosis, a common bacterial disease found in cage-cultured Asian seabass (11,14). Some members of the genus Vibrio spp., such as V. harveyi, V. alginolyticus, and V. vulnificus, are associated with infections in fish, where the host exhibits clinical signs, such as skin ulceration, scale drops on the abdomen, and necrosis of the caudal fin (9,14).…”

Possible transmission routes ofVibriospp. in tropical cage‐cultured marine fishes

“…Researchers have developed various molecular methods to identify the source of pathogens and their transmissions over space and time in different potential hosts (Cano-Gomez et al 2009;Rahman et al 2017). The housekeeping gene pyrH, encoding for uridylate monophosphate kinase was widely used to identify and characterized Vibrio isolates (Chimetto et al 2009;Sawabe et al 2013;Nurliyana et al 2019). pyrH was often used as one of the marker in MLSA analysis (Thompson et al 2005;Pascual et al 2010;Rahman et al 2014).…”