Ghost (net) Busters
Ghost Net Impacts on Coral Reefs Time to complete lesson: 20-30 minutes
Purpose of module: This module allows students to simulate the impacts of ghost nets on a coral reef. Students will build a model healthy reef ecosystem, damage it using a ghost net, and then remove it from the reef. Students will conduct a damage assessment caused by the net dragging across the reef using quadrats.
Background information: Coral reefs, also known as the rainforests of the sea, are one of the most diverse and ecologically complex marine ecosystems. They are found in warm, tropical waters with high salinity and high light exposure. A coral reef is made up of individual coral polyps that resemble tiny anemones and are attached to the reef. Each coral polyp is less than half an inch in diameter, but they live in colonies which Figure 1: A healthy coral reef system. can expand and take up the size of a small car. Reef building corals have a skeleton made of calcium carbonate, a mineral that is left behind when an individual coral dies. Another coral may settle on that spot and grow on top of the remaining skeleton. This allows a coral reef to grow a few centimeters each year, eventually reaching massive sizes. Coral reefs provide food and shelter for many plants, invertebrates, and fish. It is estimated that at least 25% of all marine life spendCredit: part MostBeautifulThings.net of their life at a coral reef. Coral reefs provide shelter for small fish, and small fish attract larger fish, which in turn attract large predators like sharks. Coral reefs encourage the growth of algae and sponges, which attract sea turtles and other herbivores, increasing the biodiversity of these ecosystems. Coral reefs also protect our coastlines by reducing wave energy up to 95%. Coral extracts can even be used to develop treatments for asthma, arthritis, cancer, and heart disease. The high biodiversity and productivity make coral reefs popular areas for both commercial and recreational fishing. However, coral reefs are very delicate and complex, and are very susceptible to damage by fisheries and derelict (lost or abandoned) fishing gear. When fishing gear, either active or derelict, comes in contact with a reef, it can cause Figure 2: A coral reef entangled in ghost fishing nets abrasions, breakage, and smothering of corals. Further damage can be inflicted when the debris is moved by tides, currents, and storms. Damage to reef-forming or hard corals can cause serious damage to a reef ecosystem and can reduce the integrity of the reef as a whole. Coral reefs are also threatened by pollution, climate change, changing ocean chemistry, and invasive species. Materials & kits: Ghost (net) Busters Ghost Net Retrieval Kit (10 coral reef set ups for groups, each containing: set of 12 reef figurines with magnets, ocean floor tray, 2 ghost nets, reef animals, laminated worksheet, plastic quadrat, dry erase markers, spinner. Detailed materials guide, including where to get supplies, is provided at end of lesson)
Instructions: • Start by introducing students to coral reefs, using the following interactive questions as a guide: Who has seen a coral reef before? Where were you? What do all these places have in common? (Warm water, near equator) What is a coral? How do they live and grow? What lives at or in a coral reef? What can impact a coral reef? (climate change, fishing, ghost nets, human interaction) • Through today’s activity, we will answer the question: How can ghost nets impact a coral reef? Review ghost nets if needed: what is a ghost net? (a fishing net that was lost or abandoned at sea) How are fishing nets lost? (usually due to storms, boat traffic, old age, and interaction with large animals) Do fishermen want to lose their nets? (No, they need their nets to make a living) What kinds of impacts do ghost nets have on the ocean? (They can catch and kill many kinds of animals, including fish and marine mammals) • Break students into 9 groups – students will work through the activity in their groups, but we will go through each part as a class one step at a time. 1. Have students start by creating a healthy coral reef model on the “sandy” portion of their tray. Note that the entire tray is under water, but the blue represents deeper water. As they build, explain that as a class today we are representing an entire reef ecosystem, like the Great Barrier Reef, and that each individual group represents a patch in that reef. Review what kinds of Figure 3: Healthy coral reef model. animals are in their coral reefs and how we know the reef is healthy (very colorful, many animals living there). 2. Students will then simulate a ghost net dragging along the reef. Have students look at their green weighted net and make observations about it. Some ghost nets, including sink-gillnets and trawls, have weights on one side and floats on the other allowing them to remain vertical in the water column. When these nets get caught on coral reefs, they will often drag across with the ocean current and cause damage to the reef. (Have students suspend their green weighted net in the blue portion of their tray, and drag the net across slowly as the ocean currents would. The net will dislodge some of the corals.) Discuss observations. 3. Have students hold up the piece(s) of coral that were knocked over the easiest and ask why they chose these ones. (These are the tall and branching corals that have lots of places for the net to become entangled). Scientists have found that these tall branching corals are damaged the most by ghost gear. Ask students if a coral can survive when knocked over or broken. (No, they are animals and they build on each other, so if one is broken nothing else can grow on top of it) Corals only grow a few centimeters a year, so if they are damaged it takes a long time to recover. 4. Next, have students rebuild their coral reef to demonstrate another ghost net impact. Remind students that in real life this would take decades or centuries to happen. 5. Now let’s take a look at what happens when a different ghost nets enter an area. Have students pick up their piece of gillnet and compare/contrast it with the green weighted net. (Have one student hold the net as it slowly sinks down through the water column.) As a net drifts down, some animals would leave the reef and escape. (Other students in group will start to remove some of the animals as the net is drifting down). When a net settles on a reef, it continues to move around with the motion of the ocean, causing the net to become Figure 4: Students placing ghost net on coral reef. tangled around the corals. Coral reefs are often damaged through fragmentation, abrasion, and smothering by nets. (Students will be the “ocean” and entangle their coral reef and animals with the net). 6. When a reef becomes entangled, some animals will continue to use it for shelter and/or food. Some of these fish are small enough to fit through the net, while others become entangled. Entangled sea life may die due to starvation or drowning, and the dead animals will attract other marine creatures to the reef. (Have students use their animals to swim in and out of the net – some will get caught along the way). 7. Wave action around reefs can increase during storms like hurricanes, causing the entangled net to drift back and forth suddenly. This can cause corals to become dislodged or break apart. (Have students simulate a hurricane by moving the net back and forth, knocking over a few corals in the process) 8. Coral reefs and other living creatures often remain entangled indefinitely, but sometimes scuba divers will work to retrieve these ghost nets and free the marine organisms entangled in them. Before removing nets, scientists will collect data on the damage caused by the ghost net, usually using quadrats. (Have students place their quadrat randomly on top of their reef and note the damage the ghost net has caused on that reef system using the directions on the worksheet. They will sample in 3 locations if time allows) 9. Finally, have students carefully remove the net from the damaged reef and put away materials. 10. Have students calculate the percent surface area damaged by the ghost net and the percentage of marine life that died as a result of entanglement using the equations on the back of the worksheet. • Discuss as a class how each reef was impacted by their ghost nets. How is it the same? How is it different? Were certain corals or animals more susceptible to damage by the net? Calculate or estimate the average percent surface area damaged by nets for the entire class. • Discuss current research on coral reefs and ghost nets. Many studies have looked at how coral reefs are damaged by derelict fishing gear, especially in Florida and the Hawaiian Islands. Damage to corals is usually in the form of tissue abrasion, which can cause individual or colony mortality. Corals can also be broken or dislodged, with branching gorgonian corals often the most affected. • Discuss other threats to coral reefs if time allows (coral bleaching, destructive fishing, climate change). • While we can sometimes disentangle a reef, it is not always possible. It is important to try to prevent the entanglement in the first place. This is where you can help! Here are some ways you can reduce ghost fishing: help with a beach clean-up and remove trash (including fishing nets) from the beach; eat fish that have been harvested sustainably and with safer fishing methods (use the Seafood Watch app as a guide, and don’t be afraid to ask where the seafood came from!); most importantly, spread the word! By teaching others about the impacts of ghost fishing gear you can help make a difference. The more people who know and care about the problem, the easier it will be to find a solution! • We also challenge you to engineer a new and innovative solution to the problem of ghost fishing gear and participate in our Ghost (net) Busters! Engineering Competition. Your job is to work with a group of peers to imagine, plan, and design/build a model of a way to make ghost nets less harmful to their environment. You may choose to make biodegradable or trackable gear, or develop a new, safer method of collecting fish from our oceans. Your designs will be evaluated by our professional engineers during the competition, with prizes for the most practical, creative, and innovative solutions!
Funding: The development of this UNCW MarineQuest Ghost (net) Busters curriculum is generously supported through NFWF’s Fishing for Energy Partnership with funding provided by Covanta.
Resources: Corals and Coral Reefs. The Ocean Portal Team at Smithsonian Institute. < http://ocean.si.edu/corals-and-coral-reefs> Coral Comeback? Ocean Today.
Materials Guide: Reef figurines with magnets: We purchased reef figurines from Amazon (https://www.amazon.com/Artificial-Decorative-Aquarium-Ornament-10- piece/dp/B01D26K44A/ref=sr_1_2?ie=UTF8&qid=1533133283&sr=8- 2&keywords=cnz++artificial+coral) and hot glued small magnets to the bottom so they would “attach” to the trays. Ocean floor tray: We used small cookie sheets and covered them with sand-colored contact paper. We indicated deeper water using transparent blue duct tape cut in a wavy pattern. (Walmart) Ghost nets: We use two different netting for the ghost nets. One was from an old seine net that we added shot weights to on one side. The second net was a cast net that we cut up. However, you could use all the same netting from a cast net as long as you add weights to one. Reef animals: We purchased a variety of animals, including colorful fish (https://www.amazon.com/Vinyl-Goldfish-pieces-Assorted- Colors/dp/B004I0SAG4/ref=sr_1_16?ie=UTF8&qid=1494003278&sr=8- 16&keywords=fish+beads), sea turtles (https://www.amazon.com/gp/product/B017Y09OD2/ref=ox_sc_act_title_1?ie=UTF8&p sc=1&smid=A2YU3VAJVHJPP1), and larger predators (https://www.amazon.com/Plastic-Figures-Birthday-CUPCAKE- Toppers/dp/B01ELYPODS/ref=sr_1_fkmr2_2?s=toys-and- games&ie=UTF8&qid=1533133858&sr=1-2- fkmr2&keywords=novelty+assorted+sharks+and+whales). Quadrat: We cut up the plastic base of a set of silk flowers from Michaels for our quadrats. These could also be 3D printed or printed on overhead sheets. Spinner: We used spinners purchased from a craft store and added a background to tell students the fate of each spin. You could also use dice to show whether animals survived, with numbers 1, 2, & 3 representing death, number 4 representing injured, and numbers 5 & 6 representing survived.
COLLECTING DATA USING A GRIDDED QUADRAT
Scientists often use quadrats to study large ecosystems like coral reefs. Today, you will use your quadrat to measure 3 areas of your reef, and then use your data to calculate impacts to the entire reef by calculating a percentage for your sampling sites. 1. Randomly place your quadrat on top of your reef, and indicate where the reef has been damaged by the ghost net using the table labeled “Location #1” below. 2. Use circles to indicate the presence of a coral and triangles to represent any animals in the quadrat. Be sure to outline the entire coral in your data collection, even if it is found in multiple boxes. 3. For each coral that has been removed or damaged by the ghost net, mark the circle with an X. If the coral is not damaged, mark it with a ✓. 4. Use the spinner for each animal in your quadrat to determine if it is found alive, dead, or injured. If your animal is dead or injured, mark the triangle with an X. If your animal is alive, mark the triangle with a ✓. 5. Repeat this process for 2 other random locations on your reef. 6. Once you have collected your data, carefully remove the ghost net. 7. Use the back of this sheet to estimate the percent surface area damaged by the ghost net and the percentage of marine life killed/injured.
Location #1 A B C
1
2
Credit: NOAA 3
Location #2 Location #3 A B C A B C
1 1
2 2
3 3
.
/<=)*'- / /<=)*'-
/ by the ghost net: ghost by the >/66'-
by the ghost net ghost the by
BY GHOST NET GHOST BY >/66'- -2324'- %
% % -2324'-
/injured = %
at was damaged at = =
899 × =
899 100 × that was killed
× 100 KILLED/INJURED 2*'2
×
animals 5#*26(
2*'2
()*+',
ANIMALS
/<
()*+',
-2324'-
/< ()*+','-
/<=)*'-
./01
#*
%#&'(
2
# -'2-
()*+','-
formula to calculate the percent of marine marine of percent the calculate to formula 0#026 32*/<'
#$ %#&'( 2
this formula to calculate the percent surface area of your coral reef th #
#$ in in survey area
# of surveyed boxes # with damaged corals damaged with # of animals dead or injured in injured survey area 0#026 your data andyour data this total # of marine animals 32*/<' total # of boxes surveyed
Use #$
CALCULATING PERCENT SURFACE CORAL OF AREA REEF DAMAGED BY GHOST NET CALCULATING PERCENTAGE MARINEOF # Use your data and ______