Academic journal article The Science Teacher

Red Tide: Harmful Algal Blooms and Global Climate Change

Academic journal article The Science Teacher

Red Tide: Harmful Algal Blooms and Global Climate Change

Article excerpt

In 2018 the Gulf coast of Florida suffered extensive damage from harmful algal blooms (HABs), from as far north as Clearwater Beach south to Naples. The bloom lasted nearly a year, picking up in intensity during the late summer months. HABs occur when conditions such as reduced salinity, higher water temperatures, light saturation, and currents cause rapid growth of algae in coastal areas or lakes (NOAA 2018). Along the Gulf Coast the predominant species of algae in HABs is the dinoflagellate Karenia brevis, which releases brevetoxins that can cause massive fish kills and result in the death of manatees, sea turtles, and seabirds. Humans can become ill by breathing in the toxins or by eating contaminated shellfish. In addition, HABs deplete the dissolved oxygen in the water, leading to the deaths of a wide variety of marine organisms (Pierce and Henry 2008).

Although this article focuses on HABs in coastal areas, algal blooms also pose a threat to inland communities. For example, in 2013, communities along the Great Lakes experienced high levels of cyanobacteria (blue-green algae) in their drinking water sources. This inland bloom caused significant lake life to die off, large scum-like substrates on the water surface, and levels of microcystin toxins 3.5 times higher than the accepted threshold in drinking water. Exacerbated by nutrient loading from urban and agricultural runoff and higher summer temperatures, algal blooms are becoming more common among inland water bodies as well as along the coasts (Watson et al. 2016).

When we think about the effects of global climate change, the images that we have in our minds are of melting glaciers, retreating sea ice, rising sea levels, and larger and more frequent catastrophic weather events like hurricanes. Climate change also increases water temperatures, and results in larger rain events that wash nutrients from soil into bodies of water, decreasing the salinity of coastal areas (Hallegraeff 2010). We have found that an examination of the relationship among these variables can be used to teach students about global climate change, HABs, and how to engage in the practices of science (Feldman et al. 2017).

Our lesson models the effects of global climate change on the growth of algae. In addition to it being inquiry-oriented, it is place-based, which provides the opportunity for students to explore the effects of global climate change on their own lives, communities, and regions. Place-based education can support environmentally responsible behavior (Cheng and Monroe 2012) by increasing students' willingness and ability to ask questions and take action related to their surroundings. The lesson responds to NSTA's recently published position statement, The Teaching of Climate Science (NSTA 2018) by incorporating climate change science into an existing curriculum without questioning its veracity.

We developed this lesson as part of an NSF-funded project to produce climate change education materials that could be incorporated into an existing high school marine science course that is offered in more than 25 high schools in our region. The development team consisted of faculty and graduate students from the University of South Florida and marine science teachers from Hillsborough County Public School district. The marine science curriculum already focused on algae as part of its Populations: Producers unit; we took the existing topics and modified them to include issues related to climate change. All of the materials are available at no cost on the project's website (see "On the web").

The purpose of the Populations: Producers unit is for students to explore how human actions influence algae growth, and the effects of algae growth on marine habitat and on human health and economy. The goal is for students to leave the classroom with an understanding of factors contributing to algal blooms, as well as motivation to pay attention to local environmental and business regulations. …

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