Screening for harmful algae and their toxins to improve shellfish quality
Monday, 20 September 2004
Phytoplankton research at the National Diagnostics Centre, NUI Galway
New molecular tests to identify the presence of dangerous phytoplankton in Irish waters are being carried out by scientists at NUI Galway. Phytoplankton are microscopic organisms and a major plant life in the sea. A small proportion of these, known as harmful algal blooms, produce substances that are toxic to humans and can cause fish kills.
This new research, being conducted by the National Diagnostics Centre in collaboration with the Martin Ryan Institute at the University, and funded by the Higher Education Authority is aimed at developing more automated tests than are currently in existence, to identify the presence of these harmful species and their toxins.
The NUI Galway project is two-pronged and involves a range of experts at the National Diagnostics Centre and the Martin Ryan Institute. The first part of the project is exploiting a molecular technology, the polymerase chain reaction (PCR) in combination with DNA probes, short specific sequences of DNA, to identify HAB species. These tests will enable rapid detection of toxic species thereby providing an early warning system for their presence in shellfish production areas.
The other part of the research programme at the NDC involves the production of antibodies specific for the algal toxins. The detection systems involving antibodies are not labour-intensive and relatively unskilled personnel can produce reliable and reproducible results.
The two major stakeholders with an interest in such a research project are the consumer and the fish-farmer. The consumer requires good quality shellfish for consumption and the fish-farmer depends on this industry for a sustainable livelihood.
When toxic phytoplankton are found in water, a decision has to be taken on the possible closure of various waters or bays in the vicinity, while follow-up examinations are carried out to ascertain if toxins are present. "Exports of Irish shellfish are currently worth €50 million annually to the Irish economy," says Dr Majella Maher, who is leading the molecular technology section of the three-year project, due to be completed next year.
Dr Maher explains that one of the drawbacks of the existing visual method of identification is that it can be difficult to identify precisely some of the toxic phytoplankton species present in samples. "However, with specific molecular tests, we could identify all toxic species," she says. "As the procedure involves fully-automated instrumentation, results become available within a single working-day."
Dr Marian Kane, Manager of the National Diagnostics Centre and one of the leaders of this project, says: "A variety of analytical methods is required for the detection and determination of algal toxins in shellfish to satisfy the requirements of both the commercial producers and the regulatory agencies".
"Antibodies are versatile tools – they are cheap to produce on a large scale and can be used for fully-automated test systems, such as biomolecular interaction analysis (BIA) assays, or packaged into rapid detection systems that can be used at the point where they are needed, rather than sending samples to laboratories for toxin detection," says Dr Kane.
This research is being carried out in collaboration with the Martin Ryan Institute, NUI Galway, and the National Marine Institute, now also based in Galway.