Redtide is a marine phenomenon and not a natural phenomina that poses great risk to the economic and health livelihood of people in ‘coastal areas’.PSP or (Paralytic shellfish poisoning) develops when an individuals or a person consumes molluscs containing ‘toxic dinoflagellates’ and suffers neurological or gastrointestinal manifestations.Four redtide, incidents in the Philippines are presented. The manner in which the issues/ problems were managed are described.The clinical features of it poisoning in the Philippines included (gastro-intestinal and neurological features) with deaths secondary to ventilatory failure. Mortality ranged from 0 percent to 12 percent in the different it episodes.The’re a lot of lessons to be learned in handling in this kinds or types of natural disaster. For an effective ‘toxicovigilance programme’, there must be a central coordinating responsible organization a clear definition of functions and roles and having good inter-agency cooperations. Appropriate surveillance procedures, prompt warning system, resources to intensify surveillance at times of risks, and the ability to impose bans on consumptions were also necessary. Poisons centres, can play an important role during times of it. This may include ‘toxicovigilant’ activities,seminars in the recognition and management of paralytic shellfish poisoning.There’s another types of poisoning including (PSP or paralytic shellfish poisoning), (ASP or Amnesic shellfish poisoning),(DSP or diarrhetic shellfish poisoning), (CFP or Ciguatera fish poisoning) and (NSP or Neurotoxin shellfish poisoning) . The contributions such as educational campaigns and early warning to consumers of the monitoring the extent of public health damage and patterns of poisoning in a coastal community is emphasized and ‘epidemiologists in investigating’.
dinoflagellates, alexandrium tamarense, phytoplankton, the (NRTTF) or National Red Tide Task Force, (PSP or paralytic shellfish poisoning), (ASP or Amnesic shellfish poisoning),(DSP or diarrhetic shellfish poisoning), (CFP or Ciguatera fish poisoning) and (NSP or Neurotoxin shellfish poisoning).
The one of the most environmental issues which have large impact in all around the world is known as “Red tides”.First I will discuss certain background data on it. Next how they can appear and who will be the responsible for it.Last I will focus on how it affects not only our “marine life” but also our lives.
Red tides is a common term given for a ” harmful algal bloom”.It is a “global phenomenon”.In dictionary definition it is “a brownish-red discoloration of marine waters caused by the presence of enormous numbers of certain microscopic flagellates,especially the dinoflagellates,that often produce a potent neurotoxin that accumulates in the tissues of shellfish,making them poisonous when eaten by humans and other vertebrates”.Dinoflagellates are normally regarded as the caustion of organism ,but not all of red tides are caused by ” dinoflagellates” and not all ” dinoflagellates” are caused by Red tides.Some red tide maybe so extensive and several ( square kilometers)of oceans maybe affected.It is formally known as “alexandrium tamarense”, produces a double shot of chemicals which one that is deadly to large organisms and one that is deadly to small predators because of its capability to kill both of those groups of animal it’s lead dam to mark it, as the potential ”killer of the ocean worlds”.Often it turns a reddish brown color ,( hence the name Red tide).There’ s a possibility are some variants of the tides that have no color at all.Red tides are caused by several species “microsopic plants” called “phytoplankton”.Red tides can live in both fresh and salt waters and can frequently found in “coastal areas”.The researchers are incompletely sure what causes the wide- spread growth of it.There are factors that promotes ” red tide” occurrences are the following : warm temperatures,high nutrient content,low salinity,calm seas and rain followed by sunny days during the “summer months”.In addition algae related to it can spread , or be carried long distances by currents,storms,winds or ships.They use much better equipment for detecting and analyzing it.In this phenomenon the responsible for this are the inter- agency commitees on environmental health chaired by the (DOH)or Department of health ,created the (NRTTF) or National Red Tide Task Force composed of different Academic Institutions and government agencies chaired by the (DA )or Department of Agriculture and (BFAR) or Bureau of Fishiries abd Aquatic Resources.The National Red Tide Task Force or (NRTTF) is dictated to monitor toxic ” red tides” in our country.This is to secure the public from the death and illness caused by rhe toxic “red tide”. Also to relieve its ‘negative impact ‘ to the ” shellfish industry “.The NRTTF ultimate goals is to minimize if not stop the occurence of (PSP) or paralytic shellfish poisoning in our country during red tide toxin outbreaks ,through an efficient management system that the management can successfully and alleviate recurring outbreaks of ” harmful algal blooms” and decentralized the shellfish bans of management to the level of provincial.Red tides occur “Worldwide” and some reports or news to point out their occurences are on the rise checking to the (NOAA) or National Oceanic and Atmospheric Administration. (HAB) or Harmful algae blooms cause a assortment of environmental health issues and problematic humans. It has a natural toxin which is not well known why those toxins are produced.The toxins are environmental chemicals.Those toxins are harmful to,coastal aesthetics and also our human health. Coastal communities that rely hugely on tourism repeatedly lose millions of dollar when dead fishes wash up on tourist fall ill,beaches or shellfishes warning are issued because of ” red tide ” or other harmful ‘algae bloom’.Also the shellfish businesses and commercial fishing lose income and also the charter boat are affected receiving numerous cancellations even if the waters are not affected by the harmful algae blooms.The death rate of fishes during red tides has extended extreme numbers.However those numbers seem extremes it is the realities of “red tide.Estimates that are more than 100 tons of fish can be killed during “red tides” in a single day.”Toxin blooms of dinoflagellates” fall in three categories: first blooms that kill fish but few vertebrates;second blooms that kill primarily invertebrates;last blooms that kill few marine organisms but the toxins are concentrated within the siphons,digestive glands or mantle cavities of filter feeding bivalve mollusc such as oysters,clams and escallops causing Paralytic Shellfish Poisoning(psp).Red tides have affected humans too.The impact is both economical and medical.There’s five different types of poisoning. The first one is (PSP or paralytic shellfish poisoning) it caused by the production of “saxitoxin” by the “alexandrium” species.It can concentrate in shellfish and when eaten affects the nervous systems and can cause muscle paralysis and high levels of PSP may lead to death.It symptoms include tingling of lips and tongue which mat begin within minutes of eating toxic shellfish may take around thirty minutes to develop.It may progress also to tingling of fingers and toes and then loss of control of arms and legs followed by difficulty in breathing.Some people experience a sense of floating.iting,nausea and cramps.It’s general.Next the (ASP or Amnesic shellfish poisoning) it caused by “domoic acid” producing benthic algae and planktonic including pseudo nitzchia pungens,pseudo nitzchia multiseries and amphora coffaeformis.It can be found in blue mussels and soft shell clams caused by pseudo nitzchia delicatissima.It neurological and gastric symptoms include dizziness,memory loss and disorientation.Next the (DSP or diarrhetic shellfish poisoning) it caused by the “dinophysis”.It symptoms include diarrhea,abdominal pain,vomitting,cramps and nausea.PSP and ASP are both that effect in nervious system.Next the (CFP or Ciguatera fish poisoning) it symptoms are temperature reversal,hallucinations,skin irritations,muscular and join pain.Last the (NSP or Neurotoxin shellfish poisoning) It symptoms are tingling of limbs,dizziness and muscle aches.Scaloops,oysters,clams and mussels are entire associated with (NSP).Action of the wave can released the algae toxins in the direction of the air causing problems of the respiratory among people closer to the shoreline specifically those with emphysema, asthma and other illnesses in respiratory.Becoming defiled with those toxins can be “deadly” unless you response necessity precautions.
Red tide is a toxic dinoflagellate, is the leading cause of ‘red tide’ algal blooms in the Philippines. Current monitoring practices do not address the need for an early warning system, due to the high costs and expertise required in the implementation of available methods. The feasibility of an inexpensive and simple method for monitoring HABs was examined. The approach was based on analysis of colour, derived from in situ digital images, supplemented by basic environmental measurements ‘ salinity, temperature, and light intensity. The influence of these parameters on growth – and thus the ability to predict a bloom – was explored, alongside the notion that P. bahamense should alter the colour balance of a water body, indicating the initiation of a bloom. Colour was analyzed in respect to the three basic components of a digital image: Red, green, and blue. Three bodies of water and three rivers surrounding the island of Palawan, Philippines were examined. The colour balance was consistent in most cases, and a unique colour composition was found for each location. Light intensity readings were always within the optimal growth range for P. bahamense, and the same is true for salinity with one exception. Temperature was too high 36% of the time, but 34% of these results exceeded the optimal range by only 1”Ce, and samples were taken at the surface. Thus, the environmental parameters examined seemed consistently within the optimal range for P. bahamense growth. In situ optical monitoring results were encouraging, but inconclusive due to the lack of a P. bahamense bloom occurrence during study. Shellfish aquaculture has continued to expand, with an ever-increasing consumer demand for shellfish-derived products worldwide, and a wide variety of different species of shellfish are cultured in various systems around the world. Increased population and human activity in the world’s coastal regions continue to harm the environmental quality of near-shore waters. This increasing anthropogenic degradation of the coastal environment also has a negative effect on the quality and quantity of coastal shellfish culture. The use of intensive or super-intensive culture systems in the production of some shellfish species, involving factors such as heavy stocking densities and the use of feed, chemicals and drugs, can easily have a detrimental impact on the local environment. Such intensive methods of culture can also be responsible for the production of potentially unsafe shellfish products for the consumer market. The issue of food safety and quality is of paramount concern to the consumers of both importing and exporting countries, and particularly important for the shellfish industry, which needs to maintain consumer confidence in its products. Food safety hazards associated with shellfish farming generally vary according to the species and the type of culture system. This paper will therefore provide information on hazards that may occur during the production stages and can affect the safety of shellfish food. The paper will focus on the three main groups of shellfish farmed around the world: molluscs, crabs and shrimp. Mollusc farming The molluscs are among the most successfully cultured and commercially important types of shellfish, and a large variety of different mollusc species are cultured throughout the world. Some, such as oysters and abalones, have a very high market value. Molluscs are generally cultivated in inshore coastal areas, using bottom and hanging/poleculturing systems. The main species cultured are clams, mussels, oysters and abalones. Clams Canada is one of the major producers of the Manila clam (Tapes philippinarum), which is one of the most commonly cultured species. The clam culture system involves three principal stages of production: seed production, nursery rearing and the grow-out stage. All three stages can be undertaken by large-scale clam farmers, but clams are usually cultured in separate specialised farms at each of the three stages. Hatcheries maintain the broodstock for seed production, which is sold to growers or nursery units. The seed can be raised to the specific sizes that growers prefer, as larger seed normally has a higher survival rate, thus making production more predictable. After the seeds have been removed from the nursery area, they will be spread on prepared sub-tidal plots where they will grow to a marketable size. Mussels Two mussel species (Mytilus edulis and M. galloprovincialis) are the principle types of cultured mussel on the coasts of the Netherlands, France and Spain. In New Zealand the green-lip mussel (Perna canaliculus) is the main cultured species of choice. In most Asian countries, mussel seed stock is collected from the wild, whereas in Western countries such as Canada the seed stock is supplied by hatcheries. The seed stock may be nursed on suitable surface materials or set on framed screens. After three months of nursing, the mussels are ready to be hung or ‘socked’ in the grow-out systems. A variety of systems are utilised for the grow-out in order to reduce losses of stock from predation. Both off-bottom systems, such as the suspended long-line and raft methods, and bottom culture techniques are used. Oysters The most commonly cultured species of oyster is the Pacific oyster (Crassostrea gigas). Other species that are grown to a lesser extent include the Pacific Kumamoto oyster (C. sikamea), European oyster (Ostrea edulis) and Eastern oyster (C. virginica) . Oyster culture methods vary widely, because many different factors ‘ including substrate type, current velocity, tidal range and phytoplankton productivity ‘ are important for culturing a specific species. Bottom culture is primarily practised by spreading the spat over the selected area in the bay and growing the young oysters to marketable size. However, to overcome predation problems, the off-bottom technique has been developed to give a variety of different methods, such as the hanging and rack systems. Another advantage of the off-bottom system is that the oysters are suspended in the water column, and less silt therefore accumulates on the oyster. Abalones Abalone (Haliotis kamtschatkana) is a high-value species for the Japanese market. The culture cycle consists of a hatchery phase, a juvenile phase, and a grow-out phase. Culture systems include the land-based tank system and suspended system . The land-based tank system with a seawater pumping unit is the most common type, but a suspended system in seawater has also been used with various types of containers, including plastic cages, plastic barrels and mesh pouches. A significant biological barrier in the culture of abalone is the slow growth rate, which currently makes it one of the most expensive shellfish to culture. The culture technique requires a fully supplemented specific feeding regime for each of the various stages of abalone culture. For the hatchery stage, the young larvae must be fed on benthic algae and diatoms which have been coated onto a selected surface. The water-flow system and aeration must be regulated to adequately replenish the algal film for the larvae until they reach the juvenile stage. The young abalone is subsequently fed with macro-algae or feed pellets in the grow-out system. Hazards to human health Bivalves are filter-feeders and feed on a wide range of phytoplankton species in the marine environment. Filterfeeders are particularly susceptible to sudden blooms of phytoplankton organisms, which can occur in nutrientenriched coastal areas and may contain biotoxins that are hazardous to human health. These toxic algae blooms are frequently referred to as ‘red tides’ in the popular literature. Paralytic shellfish poisoning (PSP) is one of the most serious diseases associated with red tides, and consumption of shellfish exposed to red tide blooms can result in high human mortality. In the Philippines consumption of shellfish exposed to an algal bloom of Pyrodinium, a toxic dinoflagellate, resulted in the deaths of at least 21 people and the hospitalisation of over 200 others in June to August 1983. Bivalves affected by red tides do not generally
628 Rev. sci. tech. Off. int. Epiz., die, but tend to accumulate toxins within their flesh. Depuration studies have shown that bivalves can be depurated, but a long time is required to make contaminated shellfish safe for human consumption, and this option is therefore uneconomical at present. Another problem associated with filter-feeding bivalves is their susceptibility in estuarine and coastal areas to contamination with domestic sewage, which is known to contain bacteria and viruses that are pathogenic to humans. Again it is known that these pathogens can accumulate in the flesh of bivalves. Major disease risks from this source are typhoid and paratyphoid fever, salmonellosis, Vibrio parahaemolyticus infection, cholera, viral hepatitis type A and viral gastroenteritis. Contaminated bivalves can be made edible by: a) re-laying, or transferring the shellfish to pollution-free waters b) depuration. These processes are expensive and require large inputs of time and labour. Diarrhetic shellfish poisoning (DSP) is a food-borne illness caused by the consumption of shellfish that contain biotoxins produced by dinoflagellates belonging to the genera Dinophysis and Prorocentrum . It is a gastrointestinal disease with no neurological symptoms. The first reported cases occurred in the Netherlands in the 1960s , and since then outbreaks have been described in Japan, Europe, South America, and the Far East. In Antwerp, Belgium, 403 cases of DSP were reported in February 2002 after consumption of blue mussels that contained biotoxins specific to dinoflagellates. The mussels were imported from Denmark and were part of a batch presenting high concentrations of okadaic acid above the regulatory limits . The cause of DSP is a group of polyethers, including okadaic acid, dinophysis toxins, pectenotoxins and yessotoxin . Poisoning caused by these toxins is probably under-diagnosed and under-reported in many parts of the world because of the non-specific symptoms and because the disease itself is often limited and mild. The much more serious PSP is due to a toxin produced by single-celled dinoflagellate algae of the genus Alexandrium which causes neurological symptoms that include paralysis, numbness and disorientation . The toxicity of PSP is estimated to be 1,000 times greater than cyanide and all cases require immediate medical attention. Apart from PSP, algal biotoxins can also cause amnesic shellfish poisoning (ASP) and neurotoxic shellfish poisoning (NSP) in people who consume contaminated shellfish. These toxins can also have adverse effects on fish, shore birds and marine mammals. The cause of ASP is domoic acid, found in marine algae and some species of diatoms. It is accumulated in a number of filter-feeding bivalve molluscs, including mussels, clams, scallops and oysters. The symptoms of ASP may vary from nausea, vomiting and diarrhoea to muscle weakness, disorientation and memory loss . Although ASP is relatively uncommon, cases have occurred in eastern Canada, North America, Spain, Ireland and Scotland, causing illness and death. The alga Karenia brevis, which produces brevetoxin, causes the gastrointestinal and neurological symptoms of NSP. Affected people can recover completely in a few days and no deaths due to the syndrome have been reported. Another algal toxin hazard is azaspiracid poisoning (AZP), produced by a dinoflagellate species, Protoperidinium sp., which also causes vomiting, diarrhoea, abdominal pain and headache. In addition, AZP may have serious longterm impacts, such as the development of pneumonia and lung tumours. In Spain, cases of V. parahaemolyticus infections are now more common in hospitals than previously. The organism has been isolated from patients with gastroenteritis in the areas where most Spanish shellfish are produced. Before 2004, most Spanish clinical isolates were serotype 04:K11, which was shown to be a unique clone distinct from Asian and American clinical strains. By mid-2004, however, all isolates of V. parahaemolyticus from the patients were 03:K6, which exhibited a pattern indistinguishable from those of pandemic strains from Asia. The pandemic 03:K6 clone of V. parahaemolyticus appeared in Asia around 1996. It spread to the United States in 1998 and more recently to Chile, where it has caused hundreds of infections, resulting in the first V. parahaemolyticus pandemic in history. The emergence of this virulent serotype in Europe is a serious public health concern that demonstrates the need to include V. parahaemolyticus in microbiological surveillance and re-examine control programmes in Europe for shellfish-harvesting areas and ready-to-eat seafood . The way forward A programme for the comprehensive monitoring and regular analysis of molluscs should be implemented to provide an early warning to the public of the appearance of biotoxins in molluscs. Samples of molluscs in growing areas should be regularly collected and tested for shellfish poisons. When the toxin level exceeds the regulatory limit, the growing area should be quarantined and sale prohibited, and the public health authorities should be informed. The programme should include a routine assessment of coastal resources for the presence of marine biotoxins and toxic phytoplankton blooming before public health is threatened. Some biotoxins may be associated with certain seasons. For instance, although azaspiracidRev. sci. tech. Off. int. Epiz., contaminated shellfish can occur in all seasons, the prevalence is much higher in the summer months .Therefore, the biotoxin distribution of each area, which may vary with the seasons, should be well documented in each country to support provision of public health measures. Crab farming Crab aquaculture has been practised for many years in Southeast Asia and is an important source of income among fish farmers. Crab culture operations have not expanded to the level of shrimp or prawn culture, and stocking densities are comparatively low. Aquaculture of mud crabs has been conducted for at least a century in the People’s Republic of China and for the past 30 years throughout Asia. Crab farming is a relatively simple aquaculture practice. Traditionally, mud crab culture was based on stocking wild-caught juveniles and adults for grow-out culture and fattening. Although hatchery production of megalopae is now feasible, the initial source of spawners and broodstock is mostly wild stock. Four species of mud crabs (Scylla sp.) are distributed in the Indo-Pacific region: S. serrata, S. olivacea, S. tranquebarica, and S. paramamosain. They are all currently recognised for culture purposes. Scylla serrata is the most commonly farmed species in many Southeast Asian countries and Australia , while S. olivacea and S. paramamosain are the two common species farmed in the lower Mekong Delta . There are two types of land-based mud crab aquacultures; one involves fattening crabs with low flesh content, and the other is grow-out of juveniles to a marketable size. Mangrove ponds/pens are used to operate two kinds of system: an intensive system with high stocking rates and supplementary feeding, and an extensive system where the stocking rate is low and there is no supplementary feeding . Various chemicals are used to control or treat disease, including malachite green, copper sulphate and zinc sulphate . Hazards to human health Vibrio cholerae is a natural bacteria occurring in brackish and estuarine waters, which can cause diarrhoea in humans. Vibrio cholerae O1 was isolated from blue crabs in Malaysia in 2003 . A case of cholera occurred in a patient in Maryland, who had eaten crab harvested commercially along the Texas coast in October 1984 .Findings of V. cholerae in the hindgut of crabs are considered to be correlated with the epidemiology and transmission of cholera in the aquatic environmentS. The way forward Crab or crab meat is normally cooked before consumption, so the health risk is low. However, contamination with bacteria that can cause human diseases may occur during the processing of crab meat, and food safety regulations should therefore be strictly applied. Shrimp farming The shrimp industry has grown v
ery rapidly in the last two decades, with a wide variety of different shrimp and prawn species being cultured in many parts of the world. The two predominant areas for large-scale culture today are Asia and South America. The giant freshwater prawn, Macrobrachium rosenbergii, has been cultured in many Southeast Asian countries for more than four decades. Pacific white shrimp (Litopenaeus vannamei) is widespread along the eastern coast of the Pacific Ocean from Mexico to northern Peru). More recently, culture of the black tiger shrimp, Penaeus monodon, has been booming in many regions. Most Latin American countries, such as Brazil, Ecuador, Panama, Peru and Mexico, use a semi-intensive system for culturing white shrimp However, since the outbreak of white spot syndrome virus in Latin American countries in 1999, some farms have changed to an intensive culture system with smaller pond sizes. In Asia, the black tiger shrimp is currently the most widely cultured type, particularly in Thailand, Indonesia, India, Vietnam, Sri Lanka, the Philippines and Malaysia. These countries together contribute about 60% of the world’s total cultured shrimp production .Most countries in Asia use semi-intensive culture systems, but Thailand, the leading shrimp exporter for over ten years, uses an intensive culture system. Currently, shrimp farming in Asia is undergoing a dramatic transformation. The white shrimp (L. vannamei) is rapidly replacing the giant or black tiger shrimp as the main farmed species. This change began in Taipei China in the late 1990s with the importation of specific-pathogen-free (SPF) broodstock of L. vannamei from Hawaii. The People’s Republic of China then began to import this broodstock, followed by Thailand, Indonesia and Vietnam, and the white shrimp is now being cultured on a very large scale. The main reason for this change is that L. vannamei has a faster growth, higher yield and lower production costs than P. monodon. The biological basis of this advantage is the SPF and domestication status of imported L. vannamei. In contrast, P. monodon post-larvae are produced from wildcaught broodstock and are both non-domesticated and contaminated with pathogens. 630 Rev. sci. tech. Off. int. Epiz.,) The impacts of shrimp farming can be categorised into two groups, environmental impact and hazards to human health. Impact of shrimp farming on the environment In the past, most shrimp farms in Southeast Asia were located in mangrove forests and used extensive culture systems. Shrimp seed was typically obtained from the wild as post-larvae, either passively in water that was pumped into the ponds, or through the collection from one location of post-larvae which were then transferred into ponds at other locations. This type of shrimp culture destroyed large areas of mangrove forests, which are the spawning ground for many species of aquatic animals, including shrimp. Mangrove forests can also protect land from waves and storms, and even offer considerable protection from such catastrophic events as tsunami. In the future, no aquaculture farming ‘ including shrimp culture ‘ should exploit these important areas. There is growing concern about environmental pollution from the rapid expansion of shrimp farm areas. In the intensive shrimp culture system, pollution from shrimp farms is directly related to excessive use of feed. The effluents from the ponds are flushed out into the surrounding water resources during the culture period or after harvest. The major components of the wastes are dissolved nutrients such as ammonia, nitrogen, carbon dioxide and phosphorus; suspended organic solids such as faeces and phytoplankton; and inorganic suspended solids such as clay particles. These wastes often exceed the natural biological capacity to degrade such materials, leading to widespread eutrophication and degradation of the environment in many areas. The way forward In order to stop the harm caused to surrounding areas by waste from shrimp farms, shrimp culture practice should be based on a recirculation system. In such a system, wastewater from shrimp culture is reused after it has been treated in various ways. The treatment processes ensure water quality, make better use of the water, and at the same time protect the environment by reducing the waste discharge. The treatment units are described in the following sections. Sedimentation pond This first treatment involves storing wastewater in a pond to remove by sedimentation any settable solids that are present. Aeration of the pond water can be used to enhance the sedimentation process and help oxidise waste organic material. The aeration process also facilitates the oxidisation of toxic gases such as ammonia, nitrite and hydrogen sulphide into other more harmless compounds. Rev. sci. tech. Off. int. Epiz., For small shrimp farms, water from cultured ponds should be kept in the sedimentation pond for an appropriate period of time (until the water quality parameters meet national requirements or regulations) before it is discharged outside the farm into surrounding water. Fish or other filter-feeding organisms These organisms are involved with the secondary treatment pond. Filter-feeding fish such as tilapia or mullet are the most common species recommended. These fish species remove any waste organic material that remains suspended in the water after the sedimentation process. Water from these ponds will then be reused for shrimp ponds during the different cycles. Hazards to human health Potential food safety risks associated with shrimp aquaculture will vary according to the system that is used. Hazards may include biological contaminants such as pathogenic bacteria, or chemical contamination by agrochemicals, veterinary drug residues and heavy metals. The reasons for these food safety hazards are very diverse, ranging from poor aquacultural practices to cultural habits of food preparation and consumption. Improper management by shrimp culturists in many countries during the grow-out period can cause human health problems. Organic fertilisers are widely used to promote phytoplankton blooms as a food source for the shrimp in the first stage of shrimp culture. Materials used to promote these blooms have included animal manures, grass, by-products from the harvesting or processing of agricultural products, waste from fisheries and aquaculture processing plants, and discarded fish. In some instances discarded fish and processing wastes have been used not only as fertiliser but as feed. Most of these bloom-creating materials clearly have the potential to introduce serious contamination hazards into the shrimp under culture conditions. The use of uncooked organisms and their by-products as feed in shrimp ponds can also promote the spread of shrimp diseases. Such raw food has a high oxygen demand that can degrade pond-water quality and so affect the health of the shrimp. Shrimp producers do not intentionally dispose of human sewage in ponds, but some farms draw water from rivers or estuaries that receive untreated human waste in the immediate vicinity of the farm. Wastes of human and animal origin are a source of pathogenic organisms that may be transmitted to humans via the products of aquaculture. Disease transmission associated with aquaculture use of excreta and wastewater has been reported by the International Reference Centre of Waste Disposal .There are potential health hazards for humans who consume inadequately cooked shrimp grown in ponds that receive human waste, untreated animal manure or organic fertilisers containing salmonella or other food-poisoning organisms. Most countries culture shrimp for export. The greatest problem affecting the export of frozen shrimp is contamination by microorganisms that are pathogenic to humans, especially Salmonella and pathogenic Vibrio spp. Environmental sources of these organisms include water, soil, insects, animal faeces, raw meats, raw poultry and raw seafood. Salmonella typhi and the paratyphoid bacteria cause acute disease, normally septicaemia, and produce typhoid or typhoid-like fever in humans. Other forms of salmonellosis generally produce milder,
gastrointestinal symptoms and have led to public health problems in various countries. Salmonella has been detected in samples of the water supply, pond water feed materials, fresh shrimp at farms and from wholesale markets, and frozen shrimp destined for export .Both V. cholerae O1 and V. cholerae non-O1 have been isolated from water of shrimp cultured in brackish water in Southeast Asia, with V. cholerae O1 present in 2% and V. cholerae non-O1 in 33% of samples. In similar studies, V. cholerae non-O1 was isolated from shrimp culture environment in India Antibiotics Current knowledge of the health and environmental impact of antibiotics used in aquaculture is poor, particularly in tropical regions. Improper use of antibiotics in hatcheries and grow-out ponds will result in antibiotic residues in cultured shrimp. Most importing countries have prohibited the use of chloramphenicol and nitrofurans in aquaculture. The Food and Drug Administration in the United States of America (USA) banned the powerful and potentially toxic chloramphenicol (one of the phenicols) in 1989 because of the risks of antibiotic resistance developing in human pathogens and a link with a rare and often fatal disease, aplastic anaemia.. Chloramphenicol is highly toxic to humans, but the antibiotics are used to treat humans in life-threatening situations when no other drug is effective. Europe, Japan and many other countries also banned the antibiotic in feed, but it is still permitted for specific veterinary treatments. Nitrofurans are also dangerous because of their potential carcinogenic properties, and so their use in animals produced for human consumption is similarly banned in the European Union and the USA. The USA is comparatively strict in this respect, limiting the use of antibiotics in aquaculture to three drugs: oxytetracycline, sulphamerazine, and a drug combination containing sulphadimethozine and ormethoprime. The occurrence of antibiotic residues in cultured shrimp from several exporting countries from Asia has led to rejection of the product in export markets. The way forward The use of chemical fertilisers, properly treated organic manure and pellet feed in ponds should be encouraged. Some uncooked food organisms may be allowed in broodstock ponds where special diets are needed for gonadal maturation, but this is an exceptional circumstance. Certified farms should not use any untreated manure or uncooked organisms in grow-out ponds. Human waste and untreated animal manure must be prevented from entering grow-out ponds. Domestic sewage should always be treated to prevent the contamination of the surrounding areas, and raw sewage should never be discharged into shrimp ponds from canals or natural water sources under any circumstances. Septic runoff from human and animal sources should also be avoided. Waste treatment systems should be maintained adequately to ensure that they do not leak into ponds or farm canals, and toilets should not be located near farm canals, farm reservoirs or shrimp ponds. Shrimp farms should have a reservoir as part of their farming system to act as a holding facility for water or as a pre-treatment pond. Water from rivers or canals should be pumped into this pond to allow organic matter and suspended solids to settle out. This practice can reduce much of the bacteria in cultured ponds. Hatcheries should pay particular attention to the use of natural organic foods and unadulterated artificial feed to produce good-quality post-larvae. The use of drugs such as chloramphenicol and nitrofurans at any stage of production should be prohibited. When antibiotics are used according to the regulations of each country and recommended safety guidelines, foods from the aquatic food chain are unlikely to pose any serious public health risks from antibiotic residues. Antibiotic use should be curtailed as much as possible to prevent the development of antibiotic-resistant bacteria in the food chain. Food safety hazards associated with products from aquaculture and the proposed application of principles of the hazard analysis and critical control point (HACCP) system have been reviewed in order to develop a general strategy to control the hazards identified. Record keeping is an essential part of good aquacultural practice and is important for HACCP implementation. The preparation of the HACCP plan, including updating and implementation, must be fully documented. Generally, records should be kept for a period of two years and be available for inspection by a regulatory authority.
A massive fish kill of bangus occurred in Bolinao, Pangasinan on February 1, 2002 involving tons of fish that were valued at P400 million pesos. Investigations conducted by the Bureau of Fisheries and Aquatic Resources Region I (BFAR) office indicated that the fish kill was a result of reduced dissolved oxygen in the water. The University of the the Philippines Marine Science Institute (UP MSI) observed the proliferation of the phytoplankton, Prorocentrum minimum that is also associated with some fish kills. A week after this event occurred, the major proponent put up a website using information and photos gathered by the MSI (UP MSI) researchers and also compiled from newspaper reports. The website displayed photos of floating dead fish in cages, beach areas covered with beds of dead milkfish, affected reef fish, land and aerial photos of the fish kill site, the clean-up that was organized by the community later and links to other daily newspaper that reported the fish kill event.
A search on the Internet showed that there were two foreign-based websites that are seriously monitoring fish kill incidents in their national waters. These are the Fish Kill Database in Australia that is being maintained by New South Wales Agriculture with URL at http://www.agric.nsw.gov/ and the North Carolina State University’s Center for Applied Aquatic Ecology monitors fish kill events in fresh- and estuarine waters in the United States. The URL is http://www.pfiesteria.org/. At present, such kind of web-base resource information for fish kill incidents do not exist in the country.
This site (http://fishkillevents.serveftp.org) initially compiled information during the 2002 fish kill in Bolinao, Pangasinan, Philippines and then proceeded with the documentation of subsequent fish kill incidents in the country. Fish kill incidents are serious issues especially where human mortalities and human impacts are involved.
A repository of historical information on fish kills incidents such as this website is a means to help policymakers, the scientific community, students and the general public to make informed decisions and to reduce the possibility of future fish kills. According to the Bureau of Fisheries and Acquatic Resources (BFAR) of the Philippines, shellfishes from the following are still positive for paralytic shellfish poison that is beyond the regulatory limit:
1. Dumanquilias Bay (Zamboanga del Sur)
2. Murcielagos Bay (Zamboanga del Norte and Misamis Occidental)
3. Balite Bay (Mati Davao Oriental)
4. coastal waters of Milagros (Masbate)
5. Bataan coastal waters (Mariveles, Limay, Orion, Pilar, Balanga, Orani, Abucay and Samal)
It should be noted that BFAR advised that all types of shellfish and Acetes sp. or alamang gathered from the areas listed above are ‘NOT SAFE’ for human consumption.
Fish, squids, shrimps and crabs are safe for human consumption provided that they are fresh and washed thoroughly, and internal organs such as gills and intestines are removed before cooking.
Microscopic algae are important food for filter-feeding bivalves (oysters, mussels, scallops and clams) and for the larvae of commercially important crustaceans and fishes. Proliferation (algal blooms) of this algae up to a million cells/ l, or cells/ml, is beneficial to aquaculture and wild fisheries operations. In some situations, however, algal blooms can cause severe economic losses to aquaculture, fisheries and tourism, and have major impacts on health and environment. There are 5,000 species of marine phytoplankton (Sournia et al. 1991). Some 300 species can, at times, occur in such high density that they discolor the surface of the sea (red tides). Only 40 species have the capacity to produce potent toxins that can find their way to fish and shellfish and, eventually, to humans. The first written reference to harmful algal bloom appears in the Bible (1,000 years B.C). In Exodus 7:20-21 is written that at that time in Egypt all the waters in the river turned into blood, and all the fish in the river died, and the river stank, and the Egyptians could not drink the water in the river. In this case, a non-toxic bloom-forming alga became so densely concentrated that it generated anoxic conditions resulting in indiscriminate kills of both fish and invertebrates. Oxygen depletion developed due to high respiration by the algae (at night or in dim light during the day), but most probably, bacterial respiration during decay of the bloom caused it. One of the first recorded fatal cases of human poisoning after eating shellfish contaminated with dinoflagellate toxins was in 1793 in Poison Cove in British Columbia. The seawater became phosphorescent due to dinoflagellate blooms. The causative alkaloid toxins, now called paralytic shellfish poisons (PSP) are so potent that about 500 micrograms of toxins, which can easily accumulate in just one serving of shellfish (100 gram), could be fatal to humans. On a global scale, close to 2,000 cases of human poisoning (15% mortality) through fish or shellfish consumption are reported each year and, if not controlled, the economic damage through reduced local consumption and reduced export of seafood products can be considerable. Whales and porpoises can also become victims when they receive toxins through the food chain via contaminated zooplankton or fish. Poisoning of manatees by dinoflagellate brevetoxins contained in salps attached to seagrass, and of pelicans by diatom domoic acid contained in anchovies have also been reported. Harmful algal bloom has become apparent only as a result of increased interest in intensive aquaculture systems for finfish. Some algal species can seriously damage fish either mechanically or through production of hemolytic subDownloaded by [18.104.22.168] from http://repository.seafdec.org.ph on March 30, 2016 at 11:31 AM CST 160 Health Management in Aquaculture stances. While wild fish stocks have the freedom to swim away from problem areas, caged fish appears to be extremely vulnerable to such noxious algal blooms. In the Philippines, red tide was reported in 1908 in Manila Bay as due to Peridinium blooms. Thereafter, minor nontoxic red tide outbreaks became almost an annual event in Manila Bay, particularly in the Cavite Area. It was not until June 1983 that the first outbreak of a toxic red tide caused by Pyrodinium bahamense var. compressa occurred in Samar, Central Philippines. In 1987, the presence of dinoflagellate blooms caused by Pyrodinium bahamense var was detected in the coastal waters of Masinloc, Zambales, extending from Subic to Santa Cruz. Almost simultaneously at that time, the toxic red tide recurred in Samar. Another case of paralytic shellfish poisoning (PSP) was reported on August 19, 1988 in Orion, Bataan, followed by another 28 cases in Limay within a four-day period. Marine fisheries Commercial fisheries include all operations using boats of more than 3 gross tons. Marine municipal fisheries include fishing operations using boats of less than 3 gross tons, or without the use of a boat. Both fisheries are surveyed using similar techniques. Information collected about commercial and municipal fisheries include weight and value of catch by species, gears and vessels used.
A challenge scientist’s face when interpreting satellite images of red tides is that what may appear to be high levels of chlorophyll could in fact be chlorophyll and something else. Shallow coastal areas are rich in sediment and organic matter deposited by rivers and stirred up by tides. So chlorophyll may be present, but it is mixed in with these other substances that influence the color and intensity of the light reflected by the ocean. One-way to determine whether a satellite has detected sediment and organic matter or chlorophyll is to look at fluorescence signals. When algae absorb light, not all of it is converted to energy; some is converted to heat, and some is released as light. The re-emitted light, called fluorescence is not the same wavelength as sunlight that is simply reflected by the surface. Chlorophyll imagery is also not sufficient to distinguish harmful from nonharmful algae. Since red tide is a natural phenomenon (not caused by human beings); when temperature, salinity, and nutrients reach certain levels, a massive increase in K. brevis algae can occur but it is unsure to what harmful effects. Another problem scientist’s face is that no one knows the exact combination of factors that causes red tide. Though this study does show that high temperatures combined with a possible lack of wind and rainfall is usually at the root of red tide blooms. However, it is natural for chlorophyll a levels to fluctuate over time. Chlorophyll a concentrations are often higher after rainfall, particularly if the rain has flushed nutrients into the water. Higher chlorophyll a levels are also common during the summer months when water temperatures and light levels are high because these conditions lead to greater phytoplankton numbers. Changes to systems which decrease (e.g. construction of canal estates) or increase (e.g. breakwaters, training water and dredging) flushing rates influence chlorophyll a concentrations also because flushing dilutes nutrients and moves them away from plants, making them less available. Conversely, slow moving or stagnant waters let nutrients increase and cell numbers grow. In conclusion, this study itself leaves opportunity for more research to investigate other parameters that may contribute to the increase in red tide events. Many parameters have been studied and are still under constant investigation. This project merely shows how temperature may play a factor in the growth of K. brevis but it could also be influenced by a combination of other parameters not studied in this investigation.
This communication is an attempt to sensitize the medical professionals as well as the public regarding the generally harmless, self-limiting nature of the red tide phenomenon.
1. Alexander, M. A., I. Blade, M. Newman, J. R. Lanzante, N. C. Lau & J. D. Scott, 2002. The atmospheric bridge: The influence of ENSO teleconnections on air-sea interaction over the global oceans. Journal of Climate 15: 2205’2231.CrossRef
2. Anderson, D. M., 1997a. Bloom dynamics of toxic Alexandrium species in the northeastern United States. Limnology and Oceanography 42: 1009’1022.CrossRef
3. Anderson, D. M., 1997b. Turning back the harmful red tide. Nature 388: 513’514.CrossRef
4. Anderson, D. M., 1998. Study of red tide monitoring and management in Hong Kong: Literature review and background information. Technical Report No. 1, Hong Kong Agriculture and Fisheries Department, 120.
5. Anderson, D. M., D. M. Kulis, G. J. Doucette, J. C. Gallager & E. Balech, 1994. Biogeography of toxic dinoflagellates in the genus Alexandriumfrom the northeast United States and Canada as determined by morphology, bioluminescence, toxin composition, and mating compatibility. Marine Biology 120: 467’478.CrossRef
6. Azanza, R. V. & F. M. Taylor, 2001. Are Pyrodinium blooms in the Southeast Asian region recurring and spreading? A review at the end of the millennium. Ambio 30: 356’364.PubMedCrossRef
7. Azanza, R. V. & I. U. Baula, 2005. Fish kills associated with Cochlodinium blooms in Palawan, the ‘last frontier’ of the Philippines. Harmful Algae News 29: 13’14.
8. Azanza, R. V., Y. Fukuyo, L. G. Yap & H. Takayama, 2005. Prorocentrum minimum bloom and its possible link to a massive fish kill in Bolinao, Pangasinan, Northern Philippines. Harmful Algae 4: 519’524.CrossRef
9. Badylak, S. & E. J. Phlips, 2004. Spatial and temporal patterns of phytoplankton composition in a subtropical coastal lagoon, the Indian River Lagoon, Florida, USA. Journal of Plankton Research 26: 1229’1247.CrossRef
10. Chua, T. E., J. N. Paw & F. Y. Guarin, 1989. The environmental impact of aquaculture and the effects of pollution on coastal aquaculture development in Southeast Asia. Marine. Pollution Bulletin 20: 335’343.CrossRef
11. Corrales, R. A. & R. Crisostomo, 1996. Variation of Pyrodinium cyst density in Manila Bay, Philippines. In Yasumoto, T., Y. Oshima & Y. Fukuyo (eds), Harmful and Toxic Algal Blooms. Intergovernmental Oceanographic Commission of UNESCO, 181’183.
12. Dahl, E. & K. Tangen, 1993. 25 years experience with Gyrodinium aureolum in Norwegian waters. In Smayda, T. J. & Y. Shimizu (eds), Toxic Phytoplankton Blooms in the Sea. Elsevier, Amsterdam, 15’22.
13. Edwards, M. & D. G. Johns, 2006. Regional climate change and harmful algal blooms in the northeast Atlantic. Limnology and Oceanography 51: 820’829.CrossRef
14. FAO/NACA, 1995. Report on a regional study and workshop on the environmental assessment and management of aquaculture development. FAO, Rome and network of aquaculture cent. in Asia and the Pacific, Bangkok, Thailand. NACA Environment Aquaculture Development Series 1: 492.
15. Garc”s-Vargasa, J., W. Schneider, R. R. Abarca del, M. R. Rodney & E. Zambrano, 2005. Inter-annual variability in the thermal structure of an oceanic time series station off Ecuador (1990’2003) associated with El Ni”o events. Deep-Sea Research I 52: 1789’1805.CrossRef
16. Global Statistics, 2000. http://www.geohive.com/.
17. Han, W. Y., 1995. Marine Chemistry of the Nansha Islands and South China Sea. China Ocean Press, Beijing.
18. Heil, C. A., P. M. Glibert & C. L. Fan, 2005. Prorocentrum minimum (Pavillard) Schiller: A review of a harmful algal bloom species of growing worldwide importance. Harmful Algae 4: 449’470.CrossRef
19. Hodgkiss, I. J. & K. C. Ho, 1997. Are changes in N:P ratios in coastal waters the key to increased red tide blooms? Hydrobiologia 352: 141-147.CrossRef
20. Hodgkiss, I. J. & S. H. Lu, 2004. The effect of nutrients and their ratios on phytoplankton abundance in Junk Bay, Hong Kong. Hydrobiologia 512: 215’229.CrossRef
21. Hu, J., H. Kawamura, H. Hong & Y. Qi, 2000. A review on the currents in the South China Sea: Seasonal circulation, South China Sea Warm Current and Kuroshio intrusion. Journal of Oceanography 56: 607’624.CrossRef
22. ICLARM, 1993. Environment and Aquaculture in Developing Countries. International Center for Living Aquatic Resources Management, Manila, Philippines, Conference Proceedings 31: 359.
23. Isoguchi, O. & H. Kawamura, 2006. El Ni”o-related offshore phytoplankton bloom events around the Spratley Islands in the South China Sea. Geophysical Research Letters 32, L21603, doi: 10.1029/2005GL024285: 2005.CrossRef
24. Ji, S., 2003. Noctiluca scintillans red tide. In Wang, Y., S. S. Wang, Y. Z. Qi, S. Ji, Y. L. Wu, J. Z. Zou, Z. X. Zhang, Y. S. Lin, Y. T. Lin, M. J. Zhou, J. C. Hong, Z. W. Xia, H. L. Qian, N. Xu, C. J. Huang & S. Liang (eds), Red Tide on the Coasts of China. Science Press, Beijing.
25. Lim, P. T., G. Usup, C. P. Leaw & T. Ogata, 2005. First report of Alexandrium taylori and Alexandrium peruvianum (Dinophyceae) in Malaysia waters. Harmful Algae 4: 391’400.CrossRef
26. Maclean, J. L., 1989. Indo-Pacific red tide, 1985’1988. Marine Pollution Bulletin 20: 304’310.CrossRef
27. Masuda, M., T. Abe, S. Kawaguchi & S. M. Phang, 2001. Taxonomic notes on marine algae from Malaysia. VI. Five species of Ceramiales (Rhodophyceae). Botanica Marina 44: 467’477.CrossRef
28. Mohsin, A. K. M. & M. A. Ambak, 1996. Marine Fishes and Fisheries of Malaysia and Neighbouring Countries. Universiti Pertanian Malaysia Press, Serdang.
29. O’Reilly, J. E., S. Maritorena, B. G. Mitchell, D. A. Siegel, K. L. Carder, S. A. Garver, M. Kahru & C. McClain, 1998. Ocean color chlorophyll algorithms for SeaWIFS. Journal of Geophysical Research 103(C11): 24,937’24,953.CrossRef
30. Philips, E. J., S. Badylak, S. Youn & K. Kelley, 2004. The occurrence of potentially toxic dinoflagellates and diatoms in a subtropical lagoon, the Indian River Lagoon, Florida, USA. Harmful Algae 3: 39’49.CrossRef
31. Pitcher, G. C. & D. Calder, 2000. Harmful algal blooms of the southern Benguela Current: A review and appraisal of monitoring from 1989 to 1997. South African Journal of Marine Science 22: 255’271.
32. Qi, Y. Z., J. F. Chen, Z. H. Wang, N. Xu, Y. Wang & P. P. Shen, 2004. Some observations on harmful algal bloom (HAB) events along the coast of Guangdong, southern China in 1998. Hydrobiologia 512: 209’214.CrossRef
33. Qi, Y. Z., P. P. Shen & Y. Wang, 2001. Taxonomy and lifecycle of genus Phaeocystis. Journal of Tropical and Subtropical Botany 9: 174’184 (in Chinese, with English abstract).
34. Qian, H. L. & S. Liang, 1999. Study on the red tide in the Pearl River Estuary and its near waters. Marine Environmental Science 18: 69’74 (in Chinese, with English abstract).
35. Qian, H. L., S. Liang & Y. Z. Qi, 2000. Study of the characteristics and the causes of formation on the red tide in coastal water of Guangdong. Ecologic Science 19: 8’16 (in Chinese, with English abstract).
36. Rosenberg, D., 1999. Environmental pollution around the South China Sea: Developing a regional response to a regional problem. Resource Management in Asia-Pacific Working Paper No. 20. Resource Management in Asia-Pacific Project, Division of Pacific and Asian History, Research School for Pacific and Asian Studies, The Australian National University Publishers, Canberra.
37. Schoemann, V., S. Becquevort, J. Stefelsb, V. Rousseau & C. Lancelot, 2005. Phaeocystis blooms in the global ocean and their controlling mechanisms: A review. Journal of Sea Research 53: 43’66.CrossRef
38. Shaw, P. T. & S. Y. Chao, 1994. Surface circulation in the South China Sea. Deep Sea Research Part I 41: 1663’1683.CrossRef
39. Stewart, J. E., 1997. Environmental impacts of aquaculture. World Aquaculture 28: 47’52.
40. Tang, D. L., I. H. Ni, D. R. Kester & F. E. Muller-Karger, 1999. Remote sensing observation of winter phytoplankton blooms southwest of the Luzon Strait in the South China Sea. Marine Ecology Progress Series 191: 43’51.CrossRef
41. Tang, D. L., B. P. Di, G. F. Wei, I. H. Ni, I. S. Oh & S. F. Wang, 2006a. Spatial, seasonal and species variations of harmful algal blooms in the South Yellow Sea and East China Sea. Hydrobiologia DOI: 10.1007/s10750-006-0108-1.
42. Tang, D. L., H. Kawamura, T. V. Dien & M. A. Lee, 2004a. Offshore phytoplankton biomass increase and its oceanographic causes in the South China Sea. Marine Ecology Progress Series 268: 31’41.CrossRef
43. Tang, D. L., H. Kawamura, H. Doan-Nhu & W. Takahashi, 2004b. Remote sensing oceanography of a harmful algal bloom off the coast of southeastern Vietnam. Journal of Geophysical Research (Ocean) 109, doi: 10.1029/2003JC002045 (C3), C03014-C03014.
44. Tang, D. L., D. R. Kester, I.-H. Ni, H. Kawamura & H. S. Hong, 2002. Upwelling in the Taiwan Strait during the summer monsoon detected by satellite and shipboard measurements. Remote Sensing of Environment 83(3): 457’471.CrossRef
45. Tang, D. L., H. Kawamura, I. S. Oh & J. Baker, 2005. Satellite evidence of harmful algal blooms and related oceanographic features in the Bohai Sea during autumn 1998. Advances in Space Research 37: 681’689.CrossRef
46. Tang, D. L., H. Kawamura, P. Shi, W. Takahashi, L. Guan, T. Shimada, F. Sakaida & O. Isoguchi, 2006b. Seasonal phytoplankton blooms associated with monsoonal influences and coastal environment in the sea areas either side of the Indochina Peninsula. Journal of Geophysical Research (Ocean) 111, G01010, doi: 10.1029/2005JG000050.
47. Tang, D. L., D. R. Kester, I. H. Ni, Y. Z. Qi & H. Kawamura, 2003a. In situ and satellite observation of a harmful algal bloom and water condition at the Pearl River estuary in late autumn 1998. Harmful Algae 2: 89’99.
48. Tang, D. L., H. Kawamura, M. A. Lee, T. V. Dien, 2003b. Seasonal and spatial distribution of chlorophyll a and water conditions in the Gulf of Tonkin, South China Sea. Remote Sensing of Environment 85(4): 475’483.CrossRef
49. Tang, K. W., H. H. Jakobsen & A. W. Visser, 2001. Phaeocystis globosa (Prymnesi ophyceae) and the planktonic food web: Feeding, growth, and trophic interactions among grazers. Limnology and Oceanography 46: 1860’1870.CrossRef
50. Taylor, F. J. R. & R. Haigh, 1993. The ecology of fish-killing blooms of the chloromonad flagellate Heterosigma in the Strait of Georgia and adjacent waters. In: Smayda, T. J. & Y. Shimizu (eds), Toxic Phytoplankton Blooms in the Sea. Elsevier, Amsterdam, 705’710.
51. Usup, G., & R. V. Azanza, 1998. Physiology and bloom dynamics of the tropical Dinoflagellate Pyrodinium bahamense. In Anderson, D. M., A. D. Cembella & G. M. Hallegraeff (eds), Physiological Ecology of Harmful Algal Blooms. NATO ASI series Vol. G41/Springer-Verlag, Berlin, 81’94.
52. Usup, G., L. C. Pin, A. Ahmad & L. P. Teen, 2002. Alexandrium (Dinophyceae) species in Malaysian waters. Harmful Algae 1: 265’275.CrossRef
53. Vila, M., J. Camp, E. Graces, M. Maso & M. Delgado, 2001. High resolution spatio-temporal detection of potentially harmful dinoflagellates in confines waters of the NW Mediterranean. Journal of Plankton Research 23: 497’514.CrossRef
54. Wang, H. K., L. M. Huang, X. P. Huang, X. Y. Song, H. J. Wang, N. J. Wu & C. Li, 2003. A red tide caused by Gyrodinium instriatum and its environmental characters in Zhujiang River estuary. Journal of Tropical Oceanography 22: 55’62 (in Chinese, with English abstract).
55. Wentz, F. J., D. K. Smith, C. A. Mears & C. L. Gentemann, 2001. Advanced Algorithms for QuikScat and SeaWinds/AMSR, International Geoscience and Remote Sensing Symposium, NASA, Sydney, New South Wales, Australia.
56. Xia, B. C. & R. H. Wu, 1996. Analysis on red tide outbreak in Dapeng bay of South China Sea through phytoplankton communities change. Acta Scientiarum Naturalium Universitatis Sunyatseni 35: 260’264 (in Chinese, with English abstract).
57. Xie, S. P., Q. Xie, D. X. Wang & W. T. Liu, 2003. Summer upwelling in the South China Sea and its role in regional climate variations. Journal of Geophysical Research (Ocean) 108(C8), 3261, doi: 10.1029/2003JC001867.
58. Xu, N., Y. Z. Qi, J. F. Chen, W. J. Huang, S. H. Lu & Y. Wang, 2003. Analysis on the cause of Phaeocystis globosa Scherffel red tide. Acta Scientiae Circumstantiae 23: 113’118 (in Chinese, with English abstract).
59. Y”iquez, A. Z., R. V. Azanza, B. Dale & F. Siringan, 2000. Dinoflagellate Cyst Record in Sediment Cores from Two Sites in Manila Bay, Philippines, with Different Degrees of Toxic Red Tide Influence. The 9th International Conference on Harmful Algal Blooms, Tasmania, Australia.
60. Yoshida, M., T. Ogata, C. V. Thuoc, K. Matsuoka, Y. Fukuyo, N. C. Hoi & M. Kodama, 2000. The first finding of toxic dinoflagellate Alexandrium minutum in Vietnam. Fisheries Science 66: 177’179.CrossRef
61. Zhu, G. H., X. R. Ning, Y. M. Cai, Z. L. Liu & Z. G. Liu, 2003. Studies on species composition and abundance distribution of phytoplankton in the South China Sea. Acta Oceanologica Sinica 25: 8’23 (in Chinese, with English abstract).
62. Zhao, H. & D. L. Tang, 2006. Annual variation of phytoplankton distributions in the South China Sea in relation with 1998 El Ni”o. Journal of Geophysical Research. 112, C02017, doi: 10.1029/2006JC003536.
1. Website: http://www.niehs.nih.gov/ BELDING, D. L. 1910. The scallop fisheries of Massachusetts: Including an account of the natural history of the common scallop. Commonwealth of Massachusetts Commission on Fisheries and Game, Marine Series No. 3. Boston, Massachusetts.
2. BUZZARDS BAY COMPREHENSIVE CONSERVATION AND MANAGEMENT PLAN. 1991. Buzzards Bay Project, Vol. I. United States Environmental Protection Agency and Massachusetts Executive Office of Environmental Affairs. Boston, Massachusetts.
3. CAPE COD MARINE WATER QUALITY TASK FORCE. 1988. Local efforts at controlling coastal pollution. A Report to the Cape Cod Planning and Economic Development Commission, Barnstable, Massachusetts.
4. CAPUZZO, J. M. AND R. E. TAYLOR, JR. 1980. Preliminary investigations of local populations of the bay scallop, Argopecten irradians irradians(Lamarck). Woods Hole Oceanographic Institution Annual Sea Grant Report 1978’79:26 Woods Hole, Massachusetts.
5. FISK, J. D., C. E. WATSON, AND P. G. COATES. 1967. A study of the Marine Resources of Pleasant Bay. Commonwealth of Massachusetts Division of Marine Fisheries, Monograph Series Number 5. Boston, Massachusetts.
6. GEISE, G. S., D. G. AUBREY, and J. T. LIU. 1989. Development, characteristics, and effects of the new Chatham Harbor inlet. Technical Report #89-19, Woods Hole Oceanographic Institute, Woods Hole, Massachusetts.
7. HIDU, H. 1969. Gregarious settling in the American oyster, Crassostrea virginica, Gmelin. Chesapeake Science, 10:85’92.CrossRef
8. MCFARIANE, S. L. 1983. Harvesting clams with a pump’the effects on the seed. Report to Town of Orleans, Orleans, Massachusetts. 13 p.
9. MACFARLANE, S. L. 1986. A comprehensive shellfish management plan for the Town of Orleans. Report to the Orleans Board of Selectment and Commonwealth of Massachusetts Division of Marine Fisheries. Orleans, Massachusetts.
10. MACFARLANE, S. L. 1991. Managing scallops, Argopecten irradians irradians (Lamarck), in Pleasant Bay, Massachusetts; Large is not always legal, p. 264’272. S. E. Shumway and P. A. Sandifer (eds.) Scallop Biology and Culture. World Aquaculture Society, Baton Rouge, Louisiana.
11. MACFARLANE, S. L. In press. Shellfish enhancement programs: are they enough to maintain a fishery resource? Proceedings of Shellfish Restoration Workshop, National Shellfisheries Association Annual Meeting, Charleston, South Carolina, 1994. A joint Environmental Protection Agency, National Shellfisheries Association and New Jersey Sea Grant Marine Advisory Service publication. Washington, D.C.
12. METCALF AND EDDY, INC. 1993. Stormwater control facilities. A report submitted to the Town of Orleans, Orleans, Massachusetts.
13. ROMAN, C. T., K. W. ABLE, K. L. HECK, Jr., J. W. PORTNOY, M. P. FAHAY, D. G. AUBREY, and M. A. LAZZARI. 1989. An ecological analysis of Nauset Marsh, Cape Cod National Seashore. National Park Service Cooperative Research Unit. Wellfleet, Massachusetts.
14. SPEER, P. E., D. G. AUBREY, AND E. RUDER. 1982. Beach changes at Nauset Inlet, Cape Cod, Massachusetts 1640’1981. Woods Hole Oceanographic Institution technical Report WHOI-82-40. Woods Hole, Massachusetts.
15. TOWN OF ORLEANS. 1994. Conservation, recreation and open space plan. Orleans, Massachusetts.
16. TOWN OF ORLEANS 1981. Annual Report, Orlenns, Massachusetts.
...(download the rest of the essay above)