Lesson Seven. Ballast Water and the Problem of the Unwanted Invaders 59. Terminal Objective

Transcription

1 and the Problem of the Unwanted Invaders Lesson Seven Terminal Objective Students will be able to describe how ballast water exchange can create an environmental problem for local ecosystems. They will also identify and evaluate possible solutions. What students should be able to explain after this lesson: Invasive species are a major threat to our environment because they can change an entire habitat, placing ecosystems at risk crowd out or replace native species that are beneficial to a habitat damage human enterprise, such as fisheries, costing the economy millions of dollars CA Science Content Standards: Biology: Ecology 6.b Students know how to analyze changes in an ecosystem resulting from changes in climate, human activity, introduction of nonnative species, or changes in population size. Materials Waterfront Wildlife Protection Video Time Required 1 class and the Problem of the Unwanted Invaders 59

2 Introduction of Lesson Essential Questions: How does the introduction of an exotic species affect a marine environment? Key Vocabulary native species invasive species ballast water food chain competition Does that have an effect on other interrelated ecosystems and their inhabitants? Background: Every hour an average of more than 2 million gallons of ballast water, meaning 2 million gallons of foreign plankton, are released in U.S. waters. Ballast water may be the source of the largest volume of foreign organisms released on a daily basis into American ecosystems. (Source: James T. Carlton, Endangered Species Update Vol.12, 1995) The Big Issue: Invasive species prey on native species, reducing and eventually eliminating major links within the food chain. Damage can be widespread, both in environmental and economic arenas. What is ballast water? Ballast water is carried in unladen ships to provide stability. It is taken on board at the port before the voyage begins and tiny stowaways, in the form of marine organisms, are taken on board with it. During the voyage, temperature changes in the ballast water and lack of food and light kill many, but not all, of these organisms. At the ships destination, the cargo is loaded and the ballast water, with its surviving stowaway organisms, is pumped out. Some of these organisms then establish populations in the surrounding waters. These organisms can be virulent microbes as well. Recently cholera was discovered in ballast water off the coast of Queensland, Australia. 60 and the Problem of the Unwanted Invaders

3 Introduction of Lesson cont d Facts about introduced species: Compared to other threats to biodiversity, invasive introduced species rank second only to habitat destruction, such as forest clearing. Of all 1,880 imperiled species in the United States, 49% are endangered because of introduced species alone or because of their impact combined with other forces. In fact, introduced species are a greater threat to native biodiversity than pollution, harvest, and disease combined. Further, through damage to agriculture, forestry, fisheries, and other human enterprises, introduced species inflict an enormous economic cost, estimated at $137 billion per year to the U.S. economy alone. Of course, some introduced species (such as most of our food crops and pets) are beneficial. However, others are very damaging. (Facts from Actionbioscience) Anticipatory Set: Create a Wanted poster and dossier for a local invasive species (Acanthogobius flavimanus, the Yellowfin Goby, due to its prevalence in the Southern California waterways). Pass out the information to students and role play the part of a government scientist briefing her staff about the latest invasive threat to our local ecosystems. Give students the basic information about the species, and the map showing the distribution of the invasion. Then instruct the students to form inquiry teams and come up with rational explanations (they must use justification to support their idea) of how the species showed up in our area. Allow students 10 minutes to brainstorm and collect their thoughts, then allow each team one minute to share their ideas with the class. and the Problem of the Unwanted Invaders 61

4 Lesson Input: If the class did not come up with the idea of the invader hitching a ride on a cargo ship, try to elicit information out of the class about trade and port commerce in Southern California. (Graphic source: GloBallast Programme IMO) ballast Water Explain to students that these species are looking to adapt to their new environment and survive. To do that, they will have to compete with the local residents for resources that it takes to sustain life. If an introduced species executes a successful invasion, it can cause a range of ecological impacts: competing with native species for food, substrate, and other resources preying upon native species altering habitat altering environmental conditions (i.e., increased water clarity due to increased filter feeding) altering the food chain displacing species and possibly causing extinctions. 62 ballast Water and the problem of the unwanted invaders

5 Lesson cont d The invasions can also have a huge impact on our economy and affect more than just the marine organisms in the local waters: reduction in fishery production physical impacts on coastal infrastructure reduction of efficiency in shipping closure of beaches and coastlines due to toxic algal blooms human health impacts from introduced pathogens the cost of addressing this issue So what is being done about this problem? Global trade and commerce is vital to our livelihood and has been going on for thousands of years. The question becomes how can the shipping and maritime industries minimize the threat of introducing exotic species into local waters thus reducing the possibility of ecosystem alteration and destruction? California passed a law in 2000 requiring all international shipping lines to exchange ballast water offshore, well outside local port waters. Students can evaluate whether or not this is a solution, or whether this still creates a problem. The Port of Long Beach discussed this issue and their solution briefly on a video clip and on their website:(see the Waterfront Wildlife Protection video) Have the students watch the clip, then discuss whether they believe this is a viable solution, or if they have ideas for anything more that could be done to help stop invasive species from being introduced to our marine ecosystems. and the Problem of the Unwanted Invaders 63

6 Closure Have students summarize the problem and what can be done about it in exactly 12 words. Share a few examples with the class. Extension Allow students to check out Columbia University s Introduced Species Summary Project: invasion_bio/inv_spp_summ/invbio_plan_report_ home.html Have students research an introduced species that is a threat to our local area in Southern California. Have them summarize the findings and report back to the class about it. This report should include possible solutions or ideas to help remediate the problem. If you would like to incorporate reading and a text-based activity into this lesson, look at the Encyclopedia of Earth online, 64 and the Problem of the Unwanted Invaders

7 Worksheet Lesson Seven Wanted: Dead or Alive Also known as: Yellowfin Goby or Japanese River Goby Crimes: taking the place of native staghorns stealing food from local tidewater goby changing the local environment illegal immigration from Japan Last Seen: Established in coastal and inland waters of central and southern California. ballast Water Your job science sleuths: Propose a method for how the invader arrived in California. Remember, you need to justify your idea, not just state your hypothesis. ballast Water and the problem of the unwanted invaders 65