The World in a Drop of Water

The Real Science Team

This month the Real Science team is focusing on one aspect of how human actions impact our environment, and illustrates the importance of using science and technology to monitor our interaction with our planet in order to help sustain and improve the lives of the world’s inhabitants.

We chose to look at algae because it is one of the tiniest yet most pervasive organisms in the world, with the ability to have a lasting impact on the lives of humans and other species.

As the scientific community continues to build a body of knowledge about our world and its changing features, we also are learning about how we humans impact our environment. One area that many scientists have studied is the phenomenon of sporadic overgrowth of algae, known as algal blooms and how these blooms impact the environment.

California Noctiluca Bloom Photo from http://www.whoi.edu/ redtide/rtphotos/noctiluca.jpg

While scientists are still trying to understand what causes some of the algal blooms, research over the past couple of decades now links some of the blooms to the actions of humans. For example, invasive species inadvertently transplanted by people, such as zebra mussels, have been linked to algal blooms in Michigan; and agricultural fertilizer runoff into the Sea of Cortez.

What are Algae?

Generally, algae are tiny organisms that are both bacteria like and plant like, however species have been grouped into the Kingdom Bacteria (prokaryotic) or Kingdom Protista (eukaryotic), respectively. Primarily, algae are found in freshwater rivers and lakes, and in saltwater such as the Gulf of Mexico, but they can be found just about everywhere, including in soil.

One scientific definition of algae is “The nine phyla which comprise the ‘algae’ are all those chlorophyll-bearing organisms (and their colorless relatives) which are thalloid, i.e., having no true roots, stems, and leaves, or leaf-like organs” (Prescott, p.3). In places such as the tropical rainforests of Chile, algae grow in pools of water that develop from heavy rainfall, and become so overgrown that they completely encompass dead tree limbs that lie on the forest floor (Peter, pp.8-9).

In balance, algae provide the critical resource of food for the benefit of a variety of ecosystems. As members of phytoplankton, these organisms help produce the oxygen that we breathe. In addition, algae are present in saltwater and freshwater bodies around the world, including some varieties that grow directly in the ice of Antarctica. In the case of the Antarctic alga, the ice melts provide algae as food for krill, which are the key diet of marine mammals such as whales (Smith, p. 14). In Kenya’s Mzima Spring, turtles carry algae on their shells, providing food for the garra, which is a tiny variety of fish. (Deeble, pp. 36- 37) and
http://www7.nationalgeographic.com/ ngm/data/2001/11/01/html/ft_20011101.2.html. The Halimeda alga is another unusual variety, because it grows encrusted with calcium carbonate, aiding the development of marine reefs, including the Great Coral Reef off the coast of Australia (Chadwick, p. 30).

Conversely, one of the most harmful varieties is the Cyanobacteria, or the blue-green alga (photo from the Smithsonian Museum), which is technically categorized as bacteria (prokaryote). This variety is linked to blooms in many places in the United States. An algal bloom is essentially a rapid growth of algae, which doesn’t sound bad until its effects are fully understood. Problems have arisen when algal blooms impact water that people and wildlife rely on to survive, since the blooms can produce dangerous toxins.

A 1991 algal bloom in Australia was suspected of causing gastrointestinal, liver, and kidney damage, as described in an article by Nova Science in the News:

“When conditions are favourable, blue-green algae populations can 'bloom', multiplying at such a rate that they dominate the local aquatic environment. At this point, problems for other organisms start to occur. The water begins to stink and a green scum may appear on the surface. Some species of blue-green algae produce toxins which are dangerous – sometimes fatal – to livestock, wildlife, marine animals and humans. The decomposition of dead blue-green algal cells by bacteria consumes oxygen. When billions of such cells die during a bloom, the water becomes oxygen-depleted. This can lead to the death of other marine organisms, including fish, which need oxygen to survive. As well, the blue-green algae contain toxins that affect human and animal health.

That case identified one type of alga, but there are others that also cause toxic algal blooms. In some cases, the blooms of the red and brown tides off the coast of Texas are so large that they actually change the color of the water, and can be seen from space satellites. The blue-green alga known as Microcystis has caused toxic algal blooms in Michigan. Gymnodinium breve, which causes red tides in Texas, is the subject of research in the gulf region. Its toxic effects on fish and shellfish (and on the people who eat the infected shellfish) are so severe that, according to Texas Environmental Profiles, a December 2001 bloom resulted in the Texas Department of Health banning shellfish harvesting for over a year in parts of Texas. In that case, Texas Environmental Profiles reported that millions of fish were killed by toxins that affected their central nervous system.
http://www.texasep.org/ html/wql/wql_5cst_redtide.html

The problems caused by algal blooms are varied. The biggest concern is the impact on the health and well-being of human populations that eat the wildlife that has fed on the toxins released by the algal blooms. Because the toxins can cause illness, or even death in some cases, a race is on to find the source of these algal blooms, and an antidote for the toxins that they produce.

The National Office for Marine Biotoxins and Harmful Algal Blooms at Woods Hole Oceanographic Institution lists six possible types of poisoning in humans from the toxins caused by algal blooms: Amnesic Shellfish Poisoning, Ciguatera Fish Poisoning, Diarrhetic Shellfish Poisoning, Neurotoxic Shellfish Poisoning, and the Paralytic Shellfish Poisoning. Some cases of these toxins have been fatal to humans, with symptoms varying from dizziness to paralysis and death. http://www.whoi.edu/redtide/illness/illness.html

The use of technology to identify the causes of the blooms has become more prevalent in the past ten years, with researchers using many strategies to understand what exactly is causing the algal blooms, including photos of blooms taken by NASA satellites. Specifically, three Stanford University researchers performed a longitudinal study that correlated algal blooms in Mexico's Sea of Cortez with the release of fertilizer in the coastal farming region of the Yaqui River Valley, which flows into the Sea of Cortez. http://news-service.stanford.edu/news /2005/march16/gulf-030905.html

These blooms led to red or brown tides, associated with large fish kills, and the depletion of oxygen in the water where the algae live. The satellite photo here shows a huge algal bloom that was linked to nitrogen fertilizer runoff from farms in the coastal areas surrounding the Sea of Cortez. (Shwartz - NASA Image April-6-1998).

While there was a suspected general connection between nitrogen fertilizer and toxic algal blooms, the research done at Stanford showed the direct correlation for the first time, with the scheduled release of fertilizer being followed by algal blooms over a period of several years, all documented by NASA satellite images.

“There has been an international effort to try to understand the productivity of the oceans and their potential vulnerability to nitrogen," said Pamela A. Matson, the dean of the School of Earth Sciences and co-author of the Nature study. "A map has been developed showing special regions in the world where nitrogen is low relative to other nutrients that phytoplankton need to grow, and the Gulf of California is one of those regions. Our study is the first to show that the addition of human-caused nutrients in these special areas causes extra blooms of phytoplankton." (Shwartz)

It is important to note that some algal blooms are natural events, and act as food producers for many animals up the food chain. However, when the blooms are particularly large, they can cause massive areas of water to become depleted of oxygen, a condition called “hypoxia,” when they are eaten by bacteria. According to Shwartz,

A massive dead zone appears every summer in the Gulf of Mexico off the coast of Louisiana and Texas. Scientists believe that agricultural runoff from the Mississippi River plays a pivotal role in creating this annual dead zone, which measured 8,500 square miles (22,000 square kilometers) in 2002-an area bigger than the state of Massachusetts.

There are other man-made problems associated with algae that do not necessarily involve algal blooms. One striking example of this is the story of the alga caulerpa taxiforma, a highly toxic variety whose story of invasion is described in Alexandre Meinesz’s “Killer Algae.” The history of this problem begins in Stuttgart, Germany in the 1980s. Over time, aquariums around Europe learned of the caulerpa’s desirable features that include its beautiful color, fast rate of growth, hardiness, resistance to cool temperatures, and its place as a secondary food source for some tropical fish. Meinesz describes how in 1982, the alga was brought to the Oceanographic Museum of Monaco, and a few years later it was found living outside of the building. The alga moved into the Mediterranean, up the French coastline, and created severe problems with coastal ecosystems. (Meinesz, Preface).

This situation is still under watch by scientists today, as they try to find ways to stop the encroachment of the caulerpa on native plants and organisms. (Meinesz, pp. 237-238)
Excerpt available at http://www.press.uchicago.edu/ cgi-bin/hfs.cgi/00/13908.ctl

In addition to the problems caused on coastal areas by algae, inland bodies of water also have been affected by toxic algae growth. A study of lakes containing zebra mussels, which is “an exotic species that has plagued bodies of water in several states since the 1980s,” shows that the water which is invaded by the mussels has “higher levels of algae that produce a toxin that can be harmful to humans and animals,” (Michigan State University).

Case Study - The Zebra Mussels and Algae:

Zebra mussels (Dreissena polymorpha) – are very small mussels native to the area around the Caspian Sea. First noticed in Lake St. Clair in the late 1980s, it is thought that the mussels were inadvertently brought to the United States in the ballast of ships that sailed to the Great Lakes by way of the Atlantic Ocean and St. Lawrence Seaway. The mussels have since spread into the Mississippi River and other inland waterways.

When news of the zebra mussel’s presence in the Great Lakes was first being reported, the main concern was over its ability to quickly multiply and clog water pipe inlets used to funnel fresh drinking water to millions of people within the region. This photo, from the National Oceanic and Atmospheric Administration (NOAA), shows how the mussels clump together, making it easy for them to create blockages in the water inlets.

The study performed by researchers from the University of Michigan reported that the Great Lakes have 3X higher levels of a species of blue-green alga known as Microcystis sp. This alga produces microcystins, a toxin that can cause liver damage in humans. Sarnelle and colleagues from University of Michigan reported that zebra mussels were the cause for the algal bloom in Michigan’s Gull Lake.
http://newsroom.msu.edu/ plugins/newsroom/printversion.asp?id=1911

So, not only do the mussels pose a threat to the ability of communities to access fresh drinking water from inland supplies, but the animals are also the cause of potentially dangerous algal blooms.

As invasive species such as the zebra mussel are introduced to the environment, the long-term effects on our ability to maintain the health of the human population and other species, within the U.S. and around the globe, is unknown.

As the world’s population increases, and farmers and companies continue to search for the easiest and least expensive ways to produce crops for the market, human activity will likely cause more environmental challenges that will not easily be resolved. We must become more proactive, environmentally. Unless we as a society support the scientific studies and enact effective measures necessary, then the problems will likely only increase in severity. The actions of the general public, farmers and corporations must not only support scientific research, but must also be fully informed by our public health officials. We must hold ourselves and our leaders accountable for ensuring that we don’t harm the ecosystems that we leave to the next generations.

'Productivity' has provided a transient benefit to our society. But if we act with indifference to our environmental and ecological balance, a price will be paid. Indifference combined with greed must not supersede the common interests of our society to protect our nurturing of the environment. What we do now will be the determining factor in whether our environment can heal. We must make informed decisions during our everyday lives, particularly to those we select to hold positions of power.

Works Cited

• Brower, K. (1991). Realms of the Sea.
  National Geographic Society: Washington DC.

• Chadwick, D. (2001, January). Kingdom of Coral: Australia's Great Barrier Reef.
  National Geographic, 30-57.

• Deeble, M, and Stone, V. (2001, November). Kenya's Mzima Spring Comes Alive.
  National Geographic, 32-47.
  Also retrieved September 27 from the World Wide Web
  http://www7.nationalgeographic.com/ngm/data/2001/11/01/html/ft_20011101.2.html

• Harmful Algae Page, The. Woods Hole Oceanographic Institution.
  Retrieved April 4, 2006 from the World Wide Web:
  http://www.whoi.edu/science/B/redtide/index.html
  And retrieved September 27, 2006 from the World Wide Web:
  http://www.whoi.edu/redtide/illness/illness.html

• Meinesz, A. (1999). Killer Algae. (Translated from the French Le Roman Noir de l'algue tueuse) University of Chicago.
  Michigan State University. Lakes with zebra mussels have higher levels of toxins, MSU research finds.
  Retrieved April 8, 2006, from the Internet:
  http://newsroom.msu.edu/plugins/newsroom/printversion.asp?id=1911

• Nova Science in the News. Toxic algal blooms - a sign of rivers under stress.
  Retrieved March 15, 2006, from the World Wide Web:
  http://www.science.org.au/nova/017/017key.htm

• Peter, C. (2001, June). Deep into the Land of Extremes: Probing Chile's Wild Coast.
  National Geographic, 3-19.

• Prescott, G.W. (1968). The Algae: A Review. Steere, W.C. and Glass, H.B., (Eds.).
  Houghton Mifflin: Boston.

• Science Daily. Scientists Study Link Between Zebra Mussels And Algae Blooms.
  Retrieved April 9, 2006, from the World Wide Web:
  Science Daily http://www.sciencedaily.com/releases/1998/09/980919115852.htm

• Shwartz, M. Ocean ecosystems plagued by agricultural runoff.
  Retrieved March 5, 2006 and September 27, 2006 from the Internet:
  http://news-service.stanford.edu/news/2005/march16/gulf-030905.html

• Smith, Roff. (2001, December). Antartica: Life at the Bottom of the World
  National Geographic, 2-35.