Understanding The Detrimental Effects of Harmful Algae in The Scientific Study of Marine Life

Marine biology and marine sciences have many avenues of research and there is always some kind of research going on in this area. One of the growing concerns of marine sciences and biology is the issue of harmful algae blooms in the seas. Harmful algal blooms (HABs) are proliferations of algae that can cause massive fish kills, contamination of seafood with toxins, and/or ecological damage through the development of anoxia or habitat alteration . These blooms have been known to cause many problems the world over. These HABs can have adverse effects on the society by economic and health risks. Many researches believe that the occurrence of HABs is growing throughout the world. Many researches are currently being undertaken on these creatures in order to find out more about their distribution, environmental impacts, and their effects on human health, but these researches have been greatly limited by critical gaps in the knowledge of the physiological, behavioral, and genetic characteristics of these things .

Normal algae are a critical part of the ecosystem. Algae, like land plants, capture the suns energy and support the food web that leads to fish and shellfish. They occur in a size range from tiny microscopic cells floating in the water column (phytoplankton) to large mats of visible macroalgae that grow on bottom sediments . These algae can become harmful if their population increases or if they start to produce some toxin. Their large populations can cause environmental problems, which include the blocking of the sunlight to the underwater plants, and the consumption of the oxygen in the water, which can lead to fish kills. Large numbers of algae can also produce a lot of pollution (scum) and might interfere with the feeding of the various fish and organisms that live in the water.

However, the most harmful effect that some of these toxic algae can have is on the human health and body. These harmful algae have been known to bloom to a high concentration in various seas of the world, leading to many health problems for humans. Sometimes, the algae grows extremely fast, or bloom, and accumulate into dense, visible patches near the surface of the water. Red Tide is a common name for such a phenomenon where certain phytoplankton species contain reddish pigments and bloom such that the water appears to be colored red. Unfortunately, a small number of species produce potent neurotoxins that can be transferred through the food web where they affect and even kill the higher forms of life such as zooplankton, shellfish, fish, birds, marine mammals, and even humans that feed either directly or indirectly on them. Scientists now prefer the term, HAB, to refer to bloom phenomenon that contain toxins or that cause negative impacts .

A lot of current research is underway in finding out more about these HABs. A recent study, titled A Molecular Basis for Differential Susceptibility and Accumulation of Paralytic Shellfish Poisoning Toxins in Commercial Bivalves (supported by grants from NOAA's Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) program and the National Institutes of Health (NIH)) has revealed that the molecular basis for resistance and accumulation of paralytic shellfish toxins (PSTs) in softshell clams . This is a big problem for the East and the West coasts of the United States. The shellfish in the area consumes the toxic algae bloom and the poison is transferred into humans when they consume the shellfish. These toxins build up in the shellfish and are extremely harmful for humans if consumed by them.

The research project related to this phenomenon started in the late 1990s when it was found that the shellfish were frequently affected by the HABs. In subsequent research, the scientists discovered that the resistance to PSTs is caused by a mutation in the gene for sodium channels, which makes them more than 1,000 times less sensitive to saxitoxin. This toxin resistance allows the clams to survive and feed during harmful algal blooms and thereby accumulate the high levels of PSTs that cause paralytic shellfish poisoning in humans . Other researches have also been conducted on the HABs in order to determine their exact physiology and the reasons for their accelerated growths and blooms. It has been found that HABs are caused by a diverse group of organisms, including toxic and noxious phytoplankton, some protists, cyanobacteria, benthic algae, and macroalgae. While some HABs occur naturally, others may be stimulated by human activities .

It has been noted that these blooms can extend over extremely large areas and can cause a lot of economic harm as well. In a recent study, average annual economic losses in the United States from HABs were approximated at $49 million, with costs attributable to maintenance of toxin monitoring programs; closures of shellfish beds; marine mammal stranding networks; collapse of some fisheries; mortality of fish, shellfish, turtles, birds, and mammals; disruptions in tourism; threats to public and coastal resource health; publication of watershed, health, and seafood advisories; and medical treatments . Even though there has been a lot of awareness created by various health agencies all over the world, human illnesses and even deaths are still reported. Some of the toxins might not be so harmful to the health but their known presence causes a lot of scare in the minds of the public and this causes a lot of aversion to local seafood products and activities. These deleterious impacts have increased public awareness and demand for intervention to reduce or eliminate bloom impacts on coastal resources, local economies, and threats to public health .

Many agencies have been involved in researching this phenomenon of the HABs. The EBCOHAB Program was started more than a decade ago and the main reason for this research has been to increase the knowledge base regarding the HABs. Three major research themes encompassing the priorities of issues of national importance on the HAB phenomenon were identified: 1) organisms, with a goal towards determining the physiological, biochemical, and behavioral features that influence bloom dynamics; 2) environmental regulation, with a goal toward determining and parameterizing the factors that govern the initiation, growth, and maintenance of these blooms; and 3) food web and community interactions, with a goal toward determining the extent to which food webs and trophic structure affect and are affected by the dynamics of HABs .

Many researches have already been conducted and many more are still underway, yet the knowledge regarding the HABs remains limited. It has been found that the toxic blooms can have an adverse effect on almost all kinds of marine food and their metabolism, viability, growth, fecundity, and recruitment of marine organisms. It has also been found that the HAB-produced toxins can have immediate, acute impacts on marine populations, including marine mammals, birds, and several protected species. Dramatic shifts in ecosystem structure can result from plankton blooms and macroalgal overgrowth in benthic systems. In this context, present knowledge is inadequate to define the scale and complexity of many HAB phenomena .