Seaweed aquaculture: a preliminary assessment of biosecurity measures for controlling the ice-ice syndrome and pest outbreaks of a Kappaphycus farm

Cicilia S B Kambey,Phaik E Lim,Iona Campbell,Adibi R M Nor,Elizabeth J Cottier-Cook,Ahemad Sade,Azhar Kassim

doi:10.1007/s10811-021-02530-z

Cicilia S B Kambey, Phaik E Lim + Show 5 more

Open Access

https://doi.org/10.1007/s10811-021-02530-z

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Abstract

The application of biosecurity in seaweed aquaculture plays an important role in reducing the impact of disease and pest outbreaks. The continuous occurrence of seaweed pests including the macroalgal epiphytes, epi-endophytic filamentous algae and biofilms on Kappaphycus farms may also potentially induce further incidences of the ice-ice syndrome. In this study, on-farm biosecurity management measures were tested on the commercially grown seaweeds Kappaphycus malesianus and Kappaphycus alvarezii during peak ice-ice season at Gallam-Gallam Village, Sabah, Malaysia. The investigation was focused on preventative control measures including the early detection of the ice-ice syndrome and pests through propagule health checks, regular cleaning of the crop thallus and associated long-line ropes and monitoring of the environment. Farm procedures and practices were also assessed in terms of their biosecurity ‘risk’ using the hazard analysis and critical control point (HCCAP) approach. Observations were replicated in two different farm management systems; one system adopted routine biosecurity measures and the other had no biosecurity measures. The results showed that the ice-ice syndrome and pest outbreak was significantly decreased by 60–75% for K. malesianus and 29–71% for K. alvarezii at the farm which adopted the routine biosecurity measures compared with the no biosecurity treatment. The biosecurity measures also significantly improved growth rate and seaweed quality. The infection levels of the epi-endophyte Melanothamnus sp. contributed to the ice-ice syndrome in K. malesianus, whilst the epiphyte coverage was correlated to the ice-ice incidence in K. alvarezii. This study provides the first evidence of biosecurity management measures significantly decreasing the incidence of the ice-ice syndrome and pests on a commercial seaweed farm.

Highlights

Seaweed is highly nutritious and has been consumed by humans for centuries
The seawater pH value ranged from 7.71 to 8.09 and was significantly greater at the biosecurity treatment farm (BTF) with an average of 8.01 ± 0.01 compared with the non-biosecurity treatment farm (NBTF) with an average of 7.97 ± 0.01 (p < 0.05; F = 9.24)
This study has demonstrated for the first time that biosecurity measures, including both preventative and detection approaches to limit coverage of epiphytes, epi-endophytes and biofilm lowered the incidence of ice-ice syndrome in Kappaphycus farm

Summary

Introduction

Seaweed is highly nutritious and has been consumed by humans for centuries. In 2018, the total production of world seaweed aquaculture reached 32 million tonnes fresh weight (FW), increasing by 200% within eight years (FAO 2020). More recent studies have found that the holobiont effect on seaweed bacteria, which are typically found on the seaweed surface, can affect health performance and resilience (Wahl et al 2012; Ward et al 2020) These factors have subsequently impacted the sustainability of the Kappaphycus/ Eucheuma value chain, which supports the viability of this industry (Nor et al 2020). Minimal biosecurity guidance and regulations in the majority of countries producing seaweeds in South-East Asia and globally have exacerbated the problem of the ice-ice syndrome and pest outbreaks in the seaweed eucheumatoid industry (Campbell et al 2020; Mateo et al 2020; Rusekwa et al 2020; Kambey et al 2020a)

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