Zebra Mussel Risk - Teacher Guide - Rmbel.info

Where could Zebra mussels invade? Risk assessment for lakes.TEACHER'S GUIDESupplies Powerpoint presentation that gives answers about each lake’s riskHandouts/reading materialso Article: Understanding Lake Datao Zebra mussel biologyo Zebra mussel habitat characteristicso Zebra mussel modes of spreado Minnesota Lake Datao Small Group Activity worksheeto Answer guideTime Required One class period, with or without homework (45‐60 minutes)Implementation Ideas Teachers can present the powerpoint presentation with the background information (15‐20min) and then move on to the small group work.Teachers can assign the following items as reading homework for students the night before thesmall group classroom activity.o Understanding lake datao Zebra mussel biologyo Zebra mussel habitat characteristicso Zebra mussel modes of spreadSmall groups can either present their findings to the rest of the class, or prepare a report tohand in.Teachers can use the powerpoint presentation that gives answers about each lake’s risk as aclassroom activity at the endStudent Objectives1. Understand the main parameters used to determine lake water quality2. Understand basic Zebra mussel biology, modes of spread, and risk for local lakes3. Critical thinking about analyzing numerous lake characteristics and assessing infestation risk1

Where could Zebra mussels invade? Risk assessment for lakes.SourcesThis lesson has been modified from the Virginia Sea Grant Marine Advisory Program.http://web.vims.edu/chessie/zmtxt.html?svr wwwActivityIntroduce students to the information from: Article: Understanding Lake Data Zebra mussel biology Zebra mussel habitat characteristics Zebra mussel modes of spreadYou may assign the reading as homework on the night before, lead a class discussion, or each smallgroup may read and discuss the information and review it with the teacher and the rest of the class.Explain that they will be working in groups to analyze scientific information in order to predict whetheror not various lakes in Minnesota are suitable habitat for zebra mussels.Divide the class into small groups. Assign roles within the groups as follows:Recorder: Keeps written notes on group discussions and observations. Records group responses toquestions on activity worksheets. Reads written information back to rest of group for their approval.Reporter: Gives verbal report to the class summarizing the group's conclusions, using the activityworksheets and other notes from the Recorder.Research Technician(s): Provide(s) additional information to the group during the problem‐solvingactivities by consulting supplementary handouts and reference materials.Give each group a set of “Minnesota Lake Data” sheets and a copy of the “Small Group ActivityWorksheet”. The students read aloud the information on their data sheets to the other group members.The Recorder reads the “Small Group Activity Worksheet” to the group.Based on this information, each group develops a prediction about the likelihood that each lake will beaffected by zebra mussels and why. The questions on the Small Group Activity Worksheet will guidetheir discussion. The Recorder writes the predictions and supporting information on this formOnce all groups have completed their report forms, each group's Reporter shares the results with therest of the class. To facilitate discussion as the class compares the sites, the Recorders can post on achart or the chalkboard the predictions for their sites, along with water quality data and other importantfacts.Toward the end of class, use the powerpoint and/or answer sheet to go over the answers about eachsite. Have the class discuss and compare their answers to the key.2

Where could Zebra mussels invade? Risk assessment for lakes.Summary and EvaluationBased on the information known about each study site, did each group make a reasonable predictionabout the zebra mussel's introduction and establishment? (See the Answers Guide for scientists'predictions.) If students disagree, remember that all of the facts are not yet known, and that there issome room for debate.3

Where could Zebra mussels invade? Risk assessment for lakes.Zebra Mussel BiologyThe zebra mussel is a freshwater bivalve mollusk, originally found in Europe in the Caspian, Aral, andBlack seas. Adult zebra mussels range from 0.5 to 3.5 cm long. The zebra mussel's scientific name isDreissena polymorpha. The name polymorpha refers to the many individual variations in the color andpattern of the shell. Most zebra mussels have striped shells, but some are solid black or brown.Zebra mussels feed on plankton, including algae, bacteria, larval animals, and other tiny particles oforganic matter suspended in the water. The mussel pumps water into its body through a siphon tubeand filters out the food. The water is pumped out through a second siphon. An adult zebra mussel filtersan average of one liter of water each day.Although they are freshwater animals, zebra mussels can survive in slightly brackish water (0.5 parts perthousand). Some adult zebra mussels have survived for several days in water with salinities as high as 12parts per thousand under controlled laboratory conditions.Zebra mussels grow and reproduce best in water which is 12 to 26C with a calcium content of at least 20parts per million. The calcium is important for the growth and maintenance of the shell.Zebra mussels are either male or female. Mature females can produce 30,000 eggs each year.Some females have produced as many as one million eggs per year. Spawning occurs when watertemperatures warm to 12 to 23C. If the water temperature remains suitable, spawning may occurseveral times during the season.A fertilized zebra mussel egg becomes a microscopic, planktonic larva. The larval mussel spends two tothree weeks swimming about, feeding on phytoplankton. During this stage, downstream currents caneasily transport the larval zebra mussel from one body of water to another.About two to three weeks after hatching, the larva begins to settle to the bottom. To survive, it mustsettle on a hard surface. Almost anything will do, including rocks, pier pilings, boats, concrete, anotheranimal's shell, aquatic plants, or submerged logs. It attaches to the surface with strong fibers calledbyssal threads. Zebra mussels frequently grow in large colonies, with hundreds of individuals attached toan object and to each other.4

Where could Zebra mussels invade? Risk assessment for lakes.Zebra Mussel Habitat CharacteristicsParameterLittle Potential forAdult SurvivalLittle Potential forLarvalDevelopmentModerate(survivable, butwill not flourish)High(favorable foroptimal growth)Calcium (mg/l)pHHardness (mg/L)Alkalinity (mg/L)Secchi depth (m)Chlorophyll a (ug/L)(food source)Total Phosphorus 8 7.0 or 9.5 30 30 1 or 8 2.5 or 258‐157.0‐7.8 or 9.0‐9.530‐3530‐351‐2 or 6‐82.0‐2.5 or 20‐2515‐307.8‐8.2 or 8.8‐9.055‐10055‐1004‐68‐20 308.2‐8.8100‐280100‐2802‐42.5‐8 5 or 505‐10 or 35‐5010‐2525‐35Data reference: Mackie and Claudi 2010Zebra Mussel Modes of SpreadZebra mussels are mainly spread by two means:1. Human activity. Zebra mussel adults can spread by bringing them into lakes when they areattached to lake equipment, boats or plants. Because the larvae are microscopic, they canspread by bringing water from one lake into another. This includes minnow buckets, live wells,boat bottoms, water boots, and any items used in lakes. Lakes with a lot of users are at a higherrisk of infestation.2. Upstream infested Lakes. Zebra mussel larvae can’t swim, they just passively float. When onelake is infested, the lakes downstream from it can become infested from the water flow.5

Where could Zebra mussels invade? Risk assessment for lakes.Minnesota Lake DataOtter Tail LakeCategoryNumber of public accessesSubstrateWater connectivityParameterHardnessAlkalinityTotal phosphorusChlorophyll aSecchi depthpHDescription3primarily sand interspersed with gravelSee mapMean value180 mg/L170 mg/L17 ug/L7 ug/L3.5 m8.3West Battle LakeCategoryNumber of public accessesSubstrateWater connectivityParameterHardnessAlkalinityTotal phosphorusChlorophyll aSecchi depthpHDescription2primarily sand and gravelSee mapMean valueNA182 mg/L14 ug/L4 ug/L4.0 m8.86

Where could Zebra mussels invade? Risk assessment for lakes.Minnesota Lake DataBig Pine LakeCategoryNumber of public accessesSubstrateWater connectivityParameterHardnessAlkalinityTotal phosphorusChlorophyll aSecchi depthpHDescription3primarily sand and rubbleSee mapMean valueNA182 mg/L35 ug/L21 ug/L2.2 m8.6Dead LakeCategoryNumber of public accessesSubstrateWater connectivityParameterHardnessAlkalinityTotal phosphorusChlorophyll aSecchi depthpHDescription3Large stands of emergent vegetation such asbulrush and wild riceSee mapMean valueNA202 mg/L24 ug/L8 ug/L3.2 m8.57

Where could Zebra mussels invade? Risk assessment for lakes.Minnesota Lake DataMiddle LeafCategoryNumber of public accessesSubstrateDescription1Sand and silt. Emergent vegetation (hardstembulrush, wild rice, and cattails) is prevalent alongthe entire shoreline of the lakeWater connectivityParameterHardnessAlkalinityTotal phosphorusChlorophyll aSecchi depthpHSee mapMean value2351921663.19.48

Where could Zebra mussels invade? Risk assessment for lakes.Minnesota Lake DataPoplar Lake, Cook CountyCategoryNumber of public accessesSubstrateWater connectivityParameterHardness (mg/L)Calcium (mg/L)Alkalinity (mg/L)Total phosphorus (ug/L)Chlorophyll a (ug/L)Secchi depth (m)pHDescription1NASee mapMean value103.5111043.17.8Gunflint Lake, Cook CountyCategoryNumber of public accessesSubstrateWater connectivityParameterHardness (mg/L)Calcium (mg/L)Alkalinity (mg/L)Total phosphorus (ug/L)Chlorophyll a (ug/L)Secchi depth (m)pHDescription1NASee mapMean value221328426.47.39

Where could Zebra mussels invade? Risk assessment for lakes.Map of selected Otter Tail County Lakes and Rivers. Arrows show the direction that the river flows.Rose Lake is red because it is infested with Zebra mussels.10

Where could Zebra mussels invade? Risk assessment for lakes.Map of selected Cook County Lakes.11

Where could Zebra mussels invade? Risk assessment for lakes.Small Group Activity WorksheetWhat is the risk of infestation for the selected lakes?Study Site: Otter Tail LakeRisk of infestation:Why:Study Site: West Battle LakeRisk of infestation:Why:Study Site: Big Pine LakeRisk of infestation:Why:12

Where could Zebra mussels invade? Risk assessment for lakes.Small Group Activity WorksheetWhat is the risk of infestation for the selected lakes?Study Site: Dead LakeRisk of infestation:Why:Study Site: Middle Leaf LakeRisk of infestation:Why:Study Site: Poplar and Gunflint LakesRisk of infestation:Why:13

Where could Zebra mussels invade? Risk assessment for lakes.Answer GuideWhat is the risk of infestation for the selected lakes?Study Site: Otter Tail LakeRisk of infestation: High, likelyWhy: The water chemistry is favorable to optimal growthIt has hard substrates for zebra mussel attachment (gravel, cobble, rocks)It is downstream from Rose Lake, which is infested alreadyIt is connected to many other lakesIt is a heavily used lake with many lake accessesStudy Site: West Battle LakeRisk of infestation: Moderately highWhy: The water chemistry is favorable to optimal growthIt has hard substrates for zebra mussel attachment (gravel, cobble, rocks)It is a heavily used lake with many lake accessesIt is connected to other lakesStudy Site: Big Pine LakeRisk of infestation: High, likelyWhy: The water chemistry is favorable to optimal growthIt has hard substrates for zebra mussel attachment (gravel, cobble, rocks)It is downstream from Rose Lake, which is infested alreadyIt is connected to many other lakesIt is a heavily used lake with many lake accesses14