Digital droplet PCR-based environmental DNA tool for monitoring Cryptocaryon irritans in a marine fish farm from Hong Kong

Tsang, Hin Hung, Domingos, Jose A., Westaway, Jacob A.F., Kam, Maximilian H.Y., Huerlimann, Roger, and Bastos Gomes, Giana (2021) Digital droplet PCR-based environmental DNA tool for monitoring Cryptocaryon irritans in a marine fish farm from Hong Kong. Diversity, 13 (8). 350.

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The adoption of new investigative strategies based on environmental DNA (eDNA) can be used to monitor parasites, associated bacterial microbiomes, and physical-chemical parameters in fish farms. In this study, we used the economically important and globally distributed fish ciliate parasite Cryptocaryon irritans as a model to understand the parasite abundance and potential drivers of its presence in marine fish farms. Environmental (rainfall) and physical-chemical (temperature, oxygen, salinity, pH) data collected from a marine fish farm in Hong Kong were analyzed together with the eDNA approach targeting C. irritans abundance based on digital droplet PCR and 16S metagenomics to determine associations and triggers between parasites and specific bacterial groups. Rainfall and temperature demonstrated positive associations with high abundance of C. irritans (eDNA) at the studied marine fish cage farm. However, rainfall was the only parameter tested that demonstrated a significant association with parasite eDNA, indicating that the raining season is a risky period for fish farmers in Hong Kong. Coraliomargarita was the bacterial genus with the most significant relationship with low abundance of C. irritans in water. Understanding the environmental triggers of ciliate parasites propagation and associated bacterial microbiome could elucidate new insights into environmental control, microbial management, and promote the reduction of chemical use in marine fish farms.

Item ID: 68916
Item Type: Article (Research - C1)
ISSN: 1424-2818
Copyright Information: Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Funders: City University of Hong Kong (CUHK), Sea Pact (SP)
Projects and Grants: SP grant number 923135, CUHK grant number 9231354, CUHK grant number 9610448
Date Deposited: 12 Aug 2021 03:32
FoR Codes: 30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3005 Fisheries sciences > 300503 Fish pests and diseases @ 100%
SEO Codes: 10 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 1002 Fisheries - aquaculture > 100202 Aquaculture fin fish (excl. tuna) @ 100%
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