Download Why are there so many jellyfish in our rivers? A Case

Why are there so many jellyfish in our rivers? A Case Study for Middle School
Abstract
In this two-day exercise, students will become farmers, tourists, fishers and scientists who
must all work together using the information they’ve learned to find out why jellyfish populations
have been blooming in their local rivers and sounds. The final activity will be a mock stakeholder
meeting where each group of students presents the information they’ve learned about their group’s
potential impact on the watershed, and through discussion, the class will come up with a solution to
the jellyfish explosion problem. Students will use critical thinking and collaboration to synthesize
information they’ve learned about life cycles, ecosystems, watersheds, food webs, and pollution to
find a solution, while learning how governments may work through the mock shareholder-meeting
environment.
Essential Standards
Occupational Courses of Study
 OBio.2.1: Analyze the interdependence of living organisms within their environment
 OBio.2.2: Understand the impact of human activities on the environment (one generation
affects the next).
Technology
 6.TT.1.1: Select appropriate technology tools to gather data and information (e.g., Webbased resources, e-books, online communication tools, etc.).
Science
 6.L.2: Understand the flow of energy through ecosystems and the responses of populations
to the biotic and abiotic factors in their environment.
 7.L.1: Understand the processes, structures and functions of living organisms that enable
them to survive, reproduce and carry out the basic functions of life.
 7.L.2: Understand the relationship of the mechanisms of cellular reproduction, patterns of
inheritance and external factors to potential variation among offspring.
 8.E.1: Understand the hydrosphere and the impact of humans on local systems and the
effects of the hydrosphere on humans.
 8.L.3: Understand how organisms interact with and respond to the biotic and abiotic
components of their environment.
 8.L.5: Understand the composition of various substances as it relates to their ability to serve
as a source of energy and building materials for growth and repair of organisms.
Social Science
 8.C&G.2: Understand the role that citizen participation plays in societal change.
Next Generation Science Standards
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MS-LS2-1: Analyze and interpret data to provide evidence for the effects of resource
availability on organisms and populations of organisms in an ecosystem
MS-LS2-2: Construct an explanation that predicts patterns of interactions among organisms
across multiple ecosystems.
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MS-LS2-4: Construct an argument supported by empirical evidence that explains how
changes to physical or biological components of an ecosystem affect populations.
MS-LS2-5: Evaluate competing design solutions for maintaining biodiversity and ecosystem
services.
Learning Objectives
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Students will describe the lifecycle of jellyfish through an activity of designing the life cycle
during class.
Students will identify the different water users and their perspective view on jellyfish blooms
and the new regulation by writing a few sentences about each water user and bringing it to
class.
Students will develop a stance for a water user (commercial fisher, scientist, farmer, and
homeowner) assigned to them in class that will be used at a mock town meeting to support
or reject the new regulation for reduction of nutrients.
Students will compare and contrast the different water users’ viewpoints to determine
similar concerns or agreements by categorizing them into main topic areas during a class
discussion.
For Resources, Handouts and more Information….
Please visit our website for a complete list of suggested resources and information to help
you with this case study. Students are encouraged to visit this site and use our recommended
resources to do their own research for the activity. We have also listed our email addresses in case
you have any comments, questions or concerns.
Contact Us
Deborah Lichti
Nina Sassano
Amber Burch
[email protected]
[email protected]
[email protected]
Day 1: Background Information
The first day will be conducted in a 50 minute period, and students will be introduced to basic
jellyfish biology by the instructor through the life cycle activity. The students will be divided into two
groups or small groups divided between the two teams (see below). Each group will learn about the
different jellyfish life stages, and bring the information to the rest of the classmates. The class will
construct the complete jellyfish lifecycle. There is a video on the website
(https://kimmeld.wordpress.com/teacherresources) for the life cycle.
Jellyfish Biology and Life Cycle
Important Terms
Phylum Cnidaria: A marine group of both fixed and mobile animals including jellyfish, sea
anemones, sea whips, and corals.
Medusa: The free-swimming adult form of many jellyfish.
Planula: The free-swimming larval form of jellyfish. The planulae use cilia, or tiny hair like structures
surrounding their body, to swim through the water.
Polyp: Also known as Scyphistoma, the sessile (attached to a surface) body form of a Cnidarian.
Other examples of polyp organisms include hydras, corals and sea anemones.
Ephyra: The asexually produced larval form of a jellyfish. Ephyra develop directly into an adult
medusa jellyfish.
Nematocyst: A capsule within the tentacle of the jellyfish that contains a trigger and a stinging
structure. This is what stings you when a Cnidarian stings you.
Encystment: Jellyfish polyps can encyst, or become enclosed in a cyst, when conditions do not
become ideal for their survival. For example, if waters become too fresh or too cold, polyps will
encyst until the following season when conditions become favorable again. This could be why
jellyfish populations are so difficult to manage.
Students will be divided into teams and will be responsible to know the different physical and
biological features of the medusa and polyp stages of the jellyfish. As a class, the students will
describe the reproductive cycle of the jellyfish, and each team will supplement the life cycle with
the information they’ve learned about specific jellyfish life forms.
For specific information about each of the following topics, please visit our website
(https://kimmeld.wordpress.com/teacherresources)
- Teams
o Team medusae
 Anatomy of a jellyfish
 Sexual reproduction
 Tentacles
 Pelagic, free swimming
o Team polyp
 Tentacles
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Sessile
Asexual
Encystment
Major Theories for Increased Jellyfish Blooms (Taken from the Barnegat Bay Partnership)
1. The “hardening” of shorelines throughout the bay (e.g., bulkheads, pilings, docks) provides
habitat for jellyfish “polyps.” Each jellyfish polyp buds off many baby jellyfish.
2. Changes in the salinity in the bay can shift the distribution of jellies in the bay, as some jellies,
including sea nettles, have a “narrow” salinity tolerance. Examples of factors that can cause largescale changes in salinity include weather conditions, increased potable water use, and large offshore
discharges of sewage effluent.
3. Increasing water temperature accelerates growth rates and maturation of sea nettles.
4. Fishing affects the abundance of jellies in the bay: different fish species may eat polyps, larvae,
and adult jellies. Some fishes and other animals also compete with jellies for their microscopic food,
such as copepods.
5. Eutrophication, an increase in the bay’s production due to nutrient loading (see a,b, and c,
above), also may affect the abundance of jellies. Nutrients stimulate the production (growth) of
phytoplankton, which leads to increases in small zooplankton (such as copepods) which are the
favorite food of jellies. Phytoplankton production also makes the water more turbid, making it
difficult for visually-feeding animals, such as fishes, to find food. Eutrophication may also reduce the
oxygen in the water. Unlike fishes and most other invertebrates, most jellies are tolerant of low
oxygen conditions.
Second Day (50 minute):
The Shareholder Meeting Scenario
A group of scientists are going to a coastal town to discuss the proposed reduction of nutrients into
the river and coastal waters. For six months, scientists are traveling around to town meetings to
gather public opinions, and hold small focus groups on the proposed regulation to help improve,
and answer any concerns or misconceptions.
The next town on the list is a small town on the coast of North Carolina. There are multiple
shareholders in the town and county. All the people attending the meeting are local residents in
the town consisting of farmers, waterfront homeowners, and commercial fishers.
Town Meeting Format
During the town meeting, the scientists begin with a 5-minute presentation about the new
regulation, and how scientific research supports the idea.
Each water user group will have 5 minutes to state their concern or support, and ask questions
about the new regulation. Each group should elect a spokesperson for the group for the initial 5
minutes.
For the last 10 minutes, the floor would be open for any group or member to speak or voice their
input concerning how this regulation may affect them.
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Farmers (crops or livestock)
o Farmers want to make sure that their profit is not being lost
o Understand as becoming farmers how their practices affect a body of water further
downstream
o Learn about fertilizing their crops and feeding their animals
o Look up riparian buffers
o Understand the best management practices of farming
o Learn about waste management for their animals
o Questions for guiding the inquiry based learning
 What is a riparian zone? How does it improve water quality?
 Why are farmers not as inclined to use riparian zones?
 How do farms up river affect the coastal community?
 What are some best farming management practices?
 What are some concerns with live stock production near rivers?
 How can the live stock producers reduce these concerns?
 What nutrients are released into the water body?
 What problems do these nutrients cause?
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Homeowners
o Watershed
o Waste management
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o Why jellyfish sting
 Nematocysts
o Why would property value decrease
o What activities would jellyfish stop them from being able to do
o Voice concerns
Commercial Fishers
o Jellyfish clog the fishing gear
o Jellyfish will eat larval fish/shrimp and outcompete fish/shrimp for food, meaning
more jellyfish less fish/shrimp = less money for the fishermen
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Scientists
o Understand riparian buffers
o Have a thorough understanding of the life cycle of the jellyfish
o Have an understanding of marine food web dynamics (who eats who)
o Understand the links between nutrient loading and construction of docks, pilings, rip
rap, bulkheading and jellyfish blooms (see online resources provided on our website
https://kimmeld.wordpress.com/teacherresources
o Overall main idea of each of the stakeholders’ main objectives
 Farmers want to earn the most money with their crops and livestock
 Tourists and homeowners want to get the most bang for their buck, in terms
of recreation, maintaining high property value, etc
 Shrimp fishers want to continue to have the best yield possible
o Questions for Inquiry Guided Learning:
 How could best farming practices help reduce jellyfish populations?
 What about the jellyfish life cycle make their populations difficult to manage?
 What are some of the things you recommend to help reduce jellyfish blooms?
Possible Points for the Students to make during the meeting
Farmers (Crops or livestock)
 They want to make sure they aren’t losing profit
o Proper storage of their animal waste and use of sustainable agriculture rather than
using pesticides and harmful chemicals.
 How their practices affect a body of water further downstream.
o Farmland can be well drained and enhanced by land drainage, where water from
excessive rainfall cannot be held in the soil structure, so the pesticides and residues
(along with nitrates and phosphates) can be transported to contaminate ground
water.
 Fertilization of their crops and feeding animals
o Over-fertilization of their crops can add to runoff from rain and be carried through
rivers and streams to sounds and the ocean, adding to the pollutants responsible for
jellyfish blooms.
o Pesticides, nutrients, pathogens (from animal waste).
 Riparian buffers
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o Forested or vegetated areas near streams that help protect those streams from land
use impacts. It provides environmental benefits that increase water quality and
reduce pollution. They intercept sediment, nutrients, pesticides and other materials
in surface runoff. They’re also key in reducing erosion by providing stream bank
stabilization.
What are the best management practices of farming
o Fertilizer consists of different amount of nitrogen, phosphorous and potassium,
which are essential for plants to grow, but are terrible for our water supply.
o Helper organisms like beneficial species of bacteria, fungi, protozoa, nematodes,
micro arthropods and earthworms can contribute to plant growth rather than using
fertilizers.
Waste management for their animals
o Storage of animal waste should be 10 meters away from a water source.
Homeowners
 Life cycle of jellyfish
o Fertilization?
o Planula larvae: larvae hatch and get transformed to free-swimming planulae, leaving
their mother’s body and going out on their own. They have a small oval shape with
tiny hairs on the surface. Planula float at the surface of water for a few days then
sinks towards the ocean bottom.
o Polyp: after the planula sinks to the bottom, it attaches to a hard, stationary surface,
then grows by forming new polyps until it has a “polyp colony” all attached to one
another. This entire stage is sessile.
o Ephyra & Medusa: when the polyp colony grows to the right size, the stalk of the
polyp will begin to develop horizontal grooves and the top groove will free itself from
the stalk as a baby jellyfish (ephyra). The ephyra will keep growing and become the
adult jellyfish that everyone would recognize.
 How a watershed works
o A drainage basin is an area of land where the water from rain or melting snow and
ice comes to a single point at the lower elevation of land and then exit the basin
where they come together to join another body of water like a river, lake, reservoir,
estuary, wetland or sea.
 Waste management
 Why jellyfish sting
o Nematocysts
 Poisons of the nematocysts vary depending on the jellyfish species—some are
harmful to humans and others just cause skin irritation.
o They don’t attack like sharks and other fish, they just slowly propel themselves along
and lie in wait for sea creatures to come to them, then whatever living thing they
touch, they sting.
 Why would property value decrease?
 What activities would jellyfish prohibit you from doing?
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o Beach vacationers are more likely to avoid certain beaches if there is a known
jellyfish bloom, or going into the water for any type of water-sport activity and risk
getting stung.
o Homeowners would not be able to use their beaches at home if there are known
large jellyfish blooms in the waters.
Voice concerns
Fishers
 Jellyfish clogging fishing gear
o In some areas, jellyfish have been known to clog fishing nets and damage fishing
gear. Capsized fishing trawls.
o Oyster farmers have been stung by long jellyfish tentacles tangled in ropes and rock
lobster anglers struggle with jellyfish clogging their equipment.
 Jellyfish will eat larval fish and shrimp and outcompete them for food
o More jellies = less fish and shrimp = less profit for fishers
o Some jellyfish species will eat the eggs and larvae of commercial and recreational fish
species, causing the number of those species to decrease. They also eat the larvae of
crabs, shrimp and oysters, increasing the predation rate of a commercially important
species.
 Suggestion that in fish farms, jellyfish mucus can clog gills of fish (like Salmon), causing the
stinging cells to swell up in the gills and the fish die from suffocation.
Scientist
 Moderate the town meeting, and allow each group to discuss the topic
 They should not accuse any one group, but work with each group to discuss how they can
improve to help the overall watershed
 The scientist should only use facts, and data to backup their discussions.