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

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.

A new Progressive Management Pathway for improving seaweed biosecurity

“…The control of grazers, epiphytes, and competing invertebrates, coupled with fouling algal outbreaks, which deter seaweed growth, is particularly difficult to manage. This is especially true for seaweeds grown under open sea conditions, as compared with land- or pond-based animal aquaculture production systems, where external conditions and hazards may be easier to mitigate 8 , 9 .…”

“…These measures significantly reduce the incidence of disease and epi-endophytes in red algal carrageenophytes Kappaphycus spp. throughout the entire cultivation period, improving both seaweed quality and market value 8 . In China, the use of bleaching powder or potassium permanganate is now routinely applied to the water supplies in seedling nurseries to prevent the growth of the main pathogenic microorganisms that are known to cause disease in the seedlings of the kelp Saccharina japonica 10 .…”

“…The biosecurity scheme will be based on existing knowledge, attitudes and practices of the farm owners and stakeholders (e.g., buyers, processors and distributors), captured using standardized interview techniques, which we have successfully trialed with over 350 seaweed farmers in the Philippines 21 , Malaysia 22 and Tanzania 23 . The information gained from these interviews, for example the common practice of unintentionally transferring infected seedlings between neighboring farms and the unequal access of women and men to training, will enable the taskforce to identify the critical risk points along the supply chain 8 and to carry out an informed risk-based analysis 9 , that is inclusive of all stakeholders 24 . It will also enable the identification of the most practical, cost-effective biosecurity measures (e.g., use of healthy and disease-resistant seedlings, quarantine and disease and pest surveillance), which are commonly used by other terrestrial agricultural sectors (e.g., maize, bananas, coffee) 25 and the seaweed industry, in the more advanced seaweed-producing countries, such as China and the Republic of Korea 3 .…”

Ice‐Ice disease: An environmentally and microbiologically driven syndrome in tropical seaweed aquaculture

“…Malaysian farmers). Between seasons, farmers are advised to carefully clean culture equipment such as ropes, particularly following IID and epiphyte outbreaks 87 ;…”

Cross-Host Protection of Marine Bacteria Against Macroalgal Disease

“…Infectious diseases have been reported as one of the main factors threatening marine macroalgae (seaweeds) in wild populations [1][2][3] and farmed species [4,5]. However, current disease management strategies, involving specific cultivation practices or chemical treatments [6,7], are often highly labor-intensive and impractical for the application to wild seaweed populations. The use of probiotics for disease control in industrial and natural systems is gaining interest [8][9][10][11][12], yet in the marine environment disease protective bacteria have predominately been characterized for aquaculture animals [13,14] with few attempts made to discover macroalgal probiotics [15][16][17].…”