Strategies in coping with the problem of harmful and toxic algal blooms - Aquaculture

STRATEGIES IN COPING WITH THE PROBLEM OF HARMFUL AND TOXIC ALGAL BLOOMS

Harmful and toxic algal bloom is one of the major public health and fishery problems in the Philippines and throughout the world. Its occurrence can cause serious social problems. The Philippine government, starting in 1984, has adopted some strategies for all red-tide affected areas in the country in an effort to detect a bloom at its early stage and minimize, if not totally eliminate, its effects on public health.

Red Tide Monitoring

Weekly or twice monthly monitoring of plankton and shellfish samples shouldbe collected in coastal areas, particularly with histories of Pyrodinium blooms. During red tide blooms, aerial surveillance from helicopters and light aircraft should be undertaken, in coordination with concerned agencies like the De-partment of Agriculture in the case of the Philippines, to determine the extent of the bloom and the movement of the visible red tide. Based on the informa-tion gathered from these aerial observations, the residents in affected areas are to be alerted.

Other hydrobiological parameters such as water temperature, salinity pH, dis-solved oxygen, phosphate-phosphorus and cyst density should be determined once a month during neap tides to minimize the tidal effect on the water samples.

Meteorological parameters such as amount of rainfall, wind force and wind direction should be taken from the records of the Philippine Atmospheric, Geo-physical and Astronomical Services Administration (PAGASA), in the case of the Philippines.

Information Dissemination

Information dissemination on red tide to alert the public through print andbroadcast media, including seminars and meetings, must be done whenever the toxicity in shellfish exceeds the regulatory limit of 80 microgram toxin per 100 g of shellfish meat. During the emergency, the people should be advised not to eat any kind of shellfish taken from red tide-infested waters.

Regulation    

A temporary ban on the harvesting, marketing and transporting of all kinds of marine shellfish from the red tide contaminated waters should be imposed upon information that the toxin level in shellfishes has exceeded the regulatory limit. Issuance of auxiliary invoices, a requirement in transporting fishery products from one place to another, should be suspended to prevent movement of the contaminated shellfish to non-affected areas. This should be matched by establishing checkpoints in strategic locations such as piers, airports and bus routes.

Medical Management of  PSP Cases

There is no antidote for the PSP toxin. Treatment is largely symptomatic, asindicated by Halstead (1965). In the Philippines, as mentioned by Gonzales(1989), it is suggested that the first thing to consider in PSP management is to empty the stomach of the victim of the toxic material as quickly as possible.

This may be done by giving the patient an oral emetic, or, when this is not available, by inserting a finger in the throat of the victim to induce vomiting. Since the toxin is water soluble, it is also recommended that the victim be given plenty of water to induce urination and minimize absorption of the toxin through the gastro-intestinal tract.

The Department of Health and the Philippine General Hospital follow a proto-col in managing PSP cases as cited by Gonzales (1986). The universal antidote for all kinds of poisoning contracted through the oral route is pure coconut milk. Gacutan (1986) suggested that this local cure for PSP is effective. How-ever, it should be emphasized, that coconut milk, or any drug for that matter, should not be given to patients starting to show symptoms of dysphagia and respiratory failure due to the risk of asphyxia.

Government Assistance Program

The occurrence of red tide, and the red tide scare itself, will adversely affect theincome of fishermen and fish vendors, while others may not even earn a singlecentavo at all. Due to economic hardship suffered by fishermen during red tide occurrences, the government, through non-government organizations and fishermen’s cooperatives, should grant red tide affected artisanal fishermen with emergency loans payable within a period of one year with affordable in- terest rate.

Recommendations

Efforts should be made to collect shellfish at regular intervals, e.g., weekly and subject this to mouse bioassay. Also, water samples must be collected weekly and analyzed for the presence of harmful and toxic algal blooms by the Bureau of Fisheries and Aquatic Resources. Efforts must also be exerted to develop the regional and provincial capabilities of the Department of Agriculture and the Department of Health on bioassay techniques to determine the presence or absence of toxin in shellfish samples. If PSP toxins are detected from the sample, a warning may be issued while waiting for the results of the confirma-tory tests to be performed on the samples by the Bureau of Food and Drugs. This way, the government may be able to respond quickly should there be a recurrence of toxic red tide.