USFWS Manatee Home Page Challenge Questions Today's News Spring's Journey North Report Your Sightings Teacher's Manual return to: A/CPB	Manatee Migration Update: February 18, 1998 Today's Report Contains: Latest Manatee Satellite Tracking Information Manatee Aerial Survey Results Challenge Questions # 3, # 4 and # 5 Answer to Last Week's Challenge Question # 1 Answer to Last Week's Challenge Question # 2 Ranger Wayne's Blue Spring Roll Call Why Does Fresh Water Float? Try This!! Today's Satellite Migration Data How to Respond to Today's Challenge Questions Latest Manatee Satellite Tracking Information "She's moving south!" exclaimed Sirenia Project biologist Cathy Beck when she sent in the latest tracking data for our six Manatees (data is at the bottom of this report). See if you can figure out which female Manatee was "moving south!", and why Cathy is so excited, by plotting the movements of the Manatees on a map. Also, be sure to look closely at the locations of Brian and Knicky, which Cathy says "are very close to each other." Photo credit:s USFWS Cathy also sent in more news about trying to recapture Brian for a quick check-up. From Cathy's description, it looks like conditions "in the field" made biologist Bob Bonde's job very interesting! "Brian, an orphan Manatee rescued in November 1993, was raised in captivity at Sea World of Florida. Since his release in South Florida in September 1997, Brian has been monitored by Sirenia Project biologists. Recently, his transmitter started to malfunction prematurely and needed to be replaced. However, Brian had been staying in a narrow canal system that made a net capture impossible. So, biologist Bob Bonde entered the water with Brian on 29 January, and swimming quietly along with him, was able to remove the old tag and replace it with a new unit. This new transmitter will stay on Brian for six more months and allow researchers, and Journey North participants, to follow his movements. Bob did notice that Brian had lost some weight since his release from captivity, which is expected when captives are released back into the wild. Sea World of Florida veterinarians and Sirenia Project biologists still hope to capture Brian soon to give him a complete physical examination." Stay tuned for more information on Brian! Manatee Aerial Survey Results We also have the results from the first aerial survey of Manatees for 1998, which was just conducted on January 29 and 30 by researchers at the Florida Department of Environmental Protection's Florida Marine Research Institute. Many thanks to Dr. Bruce Ackerman, a marine mammal biologist and coordinator of the survey, who reported to us that the researchers counted 2,019 Manatees throughout the state in this survey. This count is not considered an exact census of Manatees, though, so researchers plan to conduct additional surveys in 1998 to help refine the estimate of the minimum size of the population. Dr. Bruce Ackerman A press release sent by Dr. Ackerman reported that the survey was conducted by "a team of 31 observers, including staff from 13 agencies, research labs, and universities, [who] searched for manatees on both coasts. Observers counted 907 manatees on Florida's west coast from Apalachicola to the Everglades. Florida's east coast count was 1,112 and extended from Brunswick, Georgia to the Florida Keys. Teams of observers in 19 aircraft located and recorded Manatees in the states waters. Additionally, six ground teams counted Manatees at power plants and waterways not visible from aircraft." Take a look at the chart below, which shows the number of Manatees counted in several years since 1991. Compare the number of Manatees counted this year to earlier counts, and see if you can answer this Challenge Question: Challenge Question # 3 "How does the number of Manatees counted in January 1998 differ from previous counts? What are some of the many reasons you can think of for these differences?" (To respond to this Challenge Question, please follow the instructions at the end of this report.) Aerial Manatee Survey Results 1991 To 1998 (Courtesy of Florida Department of Environmental Protection) Date of Survey Total Count Jan. 23-24, 1991 1,268 Feb. 17-18, 1991 1,465 Jan. 17-18, 1992 1,856 Jan. 21-22, 1995 1,443 Feb. 6-7, 1995 1,822 Jan. 9-10, 1996 2,274 Feb. 18-19, 1996 2,639 Jan. 19-20, 1997 2,229 Feb. 13, 1997 1,709 Jan. 29-30, 1998 2,019 Answer to Last Week's Challenge Question # 1: Photo credit:s USFWS Last week we introduced you to Ranger Wayne Hartley at Blue Spring State Park near Orange City, Florida and we asked "Why do you think so many Manatees come to Blue Spring each winter? Why do you think a record number of Manatees have come there this season?" Ms. Hoffman's 4th and 5th grade students from Crested Butte Colorado wrote in and shared their ideas: "We are fourth and fifth graders from Crested Butte, CO. We think these are the reasons why so many manatees come to Blue Springs in the winter: In winter Blue spring is warmer than the Manatee's summer waters. In summer the Manatees migrate north, but in winter the north waters get cold so they go south.The north waters get colder in winter." Ms. Hoffman's 4th and 5th Graders Crested Butte, CO shoffman@tomichi.ghs.gunnison.k12.co.us Ms. Roggow's class from Wisconsin also sent in this answer: "We think that the reason that there are so many manatees that come to Blue Springs each Winter is there is less boat traffic and the water is warmer because of the springs. The reason there was a record number of manatees this season is because of the weather." Ms. Roggow's Class M-H-LT Elementary School, Wisconsin Sandy_Roggow@mail.mhlt.k12.wi.us Photo credit:s USFWS As the students said, Manatees do visit Blue Spring to stay warm in the winter. Blue Spring has a "run" or creek with natural springs, and the Manatees use this run as a thermal refuge from the colder waters of the St. Johns River which it connects to. According to Sirenia Project biologist Cathy Beck, Manatees seek out warmth in winter because they "are susceptible to cold-related disease, and in the winter they gather near warm water sources such as natural springs or warm water effluents of power plants." Cold temperatures can be a serious threat to the health of Manatees, and already this season our own Journey North scientists have witnessed cold related problems with Manatees. For example, in Ranger Wayne's last report he described a Manatee called "Kate" who arrived with "cold stress", and had to be taken to Sea World for medical treatment and rehabilitation. Also, Cathy Beck reported that one of the Manatees we tracked last year, "Marmontel", had died in a northern habitat area near the North River in Georgia, apparently from hypothermia, (although the final necropsy report is not conclusive.) Scientists become concerned about Manatees located in northern habitats during winter because of the risk of cold-related illness. (Now you know why Cathy Beck is excited that a Manatee was moving south). Ranger Wayne also gave an explanation for the record number of Manatees at Blue Spring this season, and the answer is related to the growing number of Manatee calves over the years. According to Ranger Wayne, "the past few seasons we have had nine calves, five calves, eight calves, eight calves, and seven calves. With six of these no longer coming in, we still have an increase of thirty-one and we cannot presume that all six missing will never come back. That is the largest reason for the increase as most of these go to raise our base population." This leads us to another Challenge Question: Challenge Question # 4 "Why do you think a large marine mammal like a Manatee cannot tolerate cold water when another large marine mammal like a Whale can?" (To respond to this Challenge Question, please follow the instructions at the end of this report.) Ranger Wayne's Blue Spring Roll Call Ranger Wayne has assembled a chart below showing several days of his daily Manatee data at Blue Spring. After youíve studied his chart, see if you can answer Challenge Question # 5 below. Roll Call Chart Date Air Temp (C) River Temp (C) Run Temp. (C) # of Manatees 11/10/97 8-23 19 nt 51 11/24/97 10-33 21 nt 13 12/08/97 15-22 16.3 22.5 70 12/22/97 19-26 16 22.9 48 01/08/98 9-31 19 nt 17 01/18/98 9-23 17.2 22.5 70 02/02/98 7-27 16 22.6 57 02/15/98 6-22 15 22.5 59 Challenge Question # 5 "Based on Ranger Wayne's data, can you see a pattern or trend that might explain the changing number of Manatees counted at Blue Spring each day?" (To respond to this Challenge Question, please follow the instructions at the end of this report.) Answer To Last Week's Challenge Question # 2 Thanks to the classes who answered last week's Challenge Question # 2, which asked "How do Manatees manage to live in both freshwater and saltwater environments?" Hereís one of the answers we received: "Manatees only need plants to survive and you can find plants in both kinds of water. Also they might have salt glands that let the water in but keep the salt out." Ms. Roggow's Class M-H-LT Elementary School, Wisconsin Sandy_Roggow@mail.mhlt.k12.wi.us Photo credit:s USFWS According to biologist Cathy Beck, "Manatees move between fresh and salt water to access various food plants in diverse habitats and to warm themselves at natural and artificial warm water sites.They require a fresh water source and acquire some or much of their fresh water needs from the plants they eat (quantity depends on what they are feeding on!). But while in salt water, they will deliberately seek out fresh water to drink - from storm drains, marina hoses, and they also have been seen, mouth open, skimming the water surface during a rain storm (since the fresh water will float on the salt water)." "The anatomy of the kidney and how it has evolved to accommodate this switch between saline and fresh water environments has been studied, most notably by Dr. Noble Maluf, an anatomist in Cleveland, Ohio. He found the kidney of the manatee is fundamentally different from that of the dugong, a strictly marine sirenian. When in salt water, the manatee kidney has an astounding ability to concentrate the urine (i.e. retain fresh water) to at least 1,160 mosM/liter (seawater is 1,000 mosM/liter)." "Movements between fresh and salt water also helps alleviate external parasites and growths on their skin. Barnacles, acquired while in saltwater, will die and fall off when the manatees move to waters with a low salinity (i.e. fresh, or nearly fresh). Algae and fungi that sometimes grow on the skin when they are in fresh water, is killed and sloughs off when they move into salt water." Why Does Fresh Water Float? Biologist Cathy Beck mentioned above that fresh water will float on salt water. But why? With these simple experiments, you can explore how and why this happens: Try This! In a tall clear glass with 8oz. of fresh (tap) water, mix in 7 tsp. of salt and stir so it is dissolved. Then, in a separate small container, mix a few drops of food coloring in a few ounces of fresh water, and stir until well mixed. Now, take an eye dropper full of the colored fresh water, and gently drop it on top of the salt water in the glass. Watch how the colored fresh water floats on top of the salt water. Why do you think this happens? For a clue, try this next experiment: But First Make a Prediction...What do you think will happen when one egg is placed in salt water and another in fresh water? Using two tall clear glasses, fill one glass with 8oz. of fresh (tap) water, and mix in 7 tsp. of salt and stir so it is dissolved; fill the second glass with 8 ounces of fresh water. Carefully place one egg in the glass with salt water, and a second egg in the glass with fresh water. Do the eggs float or sink? Why? From what you see, what can you tell about the difference between salt and fresh water? Ask yourself if you seem to float more easily when you swim in the ocean or in a lake? Today's Satellite Migration Data Go to Satellite Data Table for Dakota Go to Satellite Data Table for Brian Go to Satellite Data Table for Knicky Go to Satellite Data Table for Bailey Go to Satellite Data Table for Hillary Go to Satellite Data Table for Xena How To Respond to Challenge Questions: Please do not answer more than one question per message! How to Respond to Journey North Manatee Challenge Question # 3 Address an E-mail message to: jn-challenge-manatee@learner.org In the Subject Line of your message write: Challenge Question # 3 In the body of the message, give your answer to this question: Challenge Question # 3 "How does the number of Manatees counted in January 1998 differ from previous counts? What are some of the many reasons you can think of for these differences?" How to Respond to Journey North Manatee Challenge Question # 4 Address an E-mail message to: jn-challenge-manatee@learner.org In the Subject Line of your message write: Challenge Question # 4 In the body of the message, give your answer to this question: Challenge Question # 4 "Why do you think a large marine mammal like a Manatee cannot tolerate cold water when another large marine mammal like a Whale can?" How to Respond to Journey North Manatee Challenge Question # 5 Address an E-mail message to: jn-challenge-manatee@learner.org In the Subject Line of your message write: Challenge Question # 5 In the body of the message, give your answer to this question: Challenge Question # 5 "Based on Ranger Wayne's data, can you see a pattern or trend that might explain the changing number of Manatees counted at Blue Spring each day?" The Next Manatee Update will Be Posted on March 4, 1998. Copyright 1998 Journey North. All Rights Reserved.