On a mission to help marine mammals
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Taking action during a manatee emergency
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More than 1,100 Florida manatees were estimated to have died between January and early December 2021 amid multiple challenges, including: severe declines in food (seagrasses) on Florida’s Atlantic coast, particularly in the Indian River Lagoon; red tide in the Gulf of Mexico; boat strikes; and cold temperatures. The Atlantic coast manatees are experiencing an unusual mortality event so significant that, just as this fiscal year ended, the Florida Fish and Wildlife Conservation (FWC) announced they were planning experimental, supplemental feeding of some manatees in the northern Indian River Lagoon. Mote scientists’ surveys are providing vital data on manatees facing the worst of this year’s challenges. Knowledge is critical for informed response efforts.
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In February and April 2021, Mote scientists and Save The Manatee Club partnered for aerial surveys of Brevard County waters where FWC has rescued or recovered elevated numbers of sick or deceased manatees—part of an unusual mortality event affecting manatees in the Atlantic management area. The last regular aerial surveys of this Brevard stretch were done by Mote each winter from 2010–2015. The new surveys helped confirm that manatees had shifted their distribution away from areas where seagrass had declined.
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As the fiscal year drew to a close, FWC and Mote scientists launched a new series of aerial surveys of the Indian River Lagoon, which covers portions of Brevard and adjacent counties, and where seagrass declines have left many manatees at risk of starvation.
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Mote’s photo-ID surveys in Broward County (several counties south of Brevard) documented 400 individual manatees in winter 2020-2021, including animals that appeared malnourished—suggesting they had come from areas affected by seagrass die offs. These Broward surveys, in their third year, began with the goal of documenting manatees’ status during the modernization of the Dania Beach Clean Energy Center, one of the power plants whose outflows manatees have used as a warm-water refuge. Now, however, survey information is even more critical for understanding the ripple effects of the seagrass loss in the Indian River Lagoon on the manatees that travel up and down Florida’s Atlantic coast.
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Some individual manatees documented this year have been recognized by scientists for as long as 42 years, and 66 of the individuals have photo-ID records in the Manatee Individual Photo-identification System (MIPS) managed by the U.S. Geological Survey (USGS), FWC and Mote. As a MIPS partner with extensive experience identifying individual manatees, Mote scientists help identify manatees rescued alive or recovered deceased—providing life history information for those individuals and potentially providing important insights about when, how and why a manatee has become injured, sick or deceased.
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This year Mote scientists assembled a team to conduct the first drone surveys to monitor for critically ill manatees in the Indian River Lagoon—an effort geared toward helping animal rescuers search for manatees that might not be seen from land but are high priority to rescue. Led by Mote, the multi-institution project team was recruiting drone pilot volunteers certified by the Federal Aviation Administration and finalizing its plans to launch its first surveys of manatee aggregation sites in the Indian River Lagoon just as the fiscal year came to a close. Project partners include the University of Florida (UF), Save The Manatee Club, Blue World Research Institute, Hubbs-SeaWorld Research Institute and Florida Atlantic University, working under UF’s government permit.
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In addition, Mote’s ongoing surveys provided valuable data about manatees in other areas, including red tide-affected waters of southwest Florida:
This year Mote scientists:-
Counted 189 and 190 manatees in Sarasota County waters during two aerial (airplane) surveys conducted in June 2021—another Sarasota County record high. These surveys are funded by a grant from Sarasota County’s West Coast Inland Navigation Program.
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Documented fewer manatees in some aerial surveys as a harmful algal bloom of Karenia brevis (Florida red tide) persisted along Florida’s west coast during summer through fall. It’s unclear if the animals moved away from the area or if they were just harder to see as the microscopic algae reduced water clarity.
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Identified 426 individual manatees through 187 photo-ID surveys in southwest Florida. Of those, 192 manatees have been observed repeatedly and six have been known for as long as 38 years. One manatee seen in Fort Myers this past winter has been previously observed in Miami, one of the few observations of manatees moving from one side of Florida to the other.
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Documented eight mating herds (multiple male manatees attempting to mate with a female in estrus) or escort herds (before mating attempts begin) in southwest Florida. Many herds were observed on public beaches, allowing Mote staff to educate the public about manatees, how to protect them, and Mote’s research.
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Also this year, Mote scientists published high-impact discoveries and expanded Mote’s long-standing manatee research in fascinating new directions. For example, Mote scientists:
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Co-authored the first record of a Florida manatee traveling to the Mexican Caribbean—a journey that likely covered at least 620 miles (1,000 kilometers), and potentially more than 3,100 miles (5,000 kilometers) if the manatee took the longest plausible route. This brief report, “First documentation of long-distance travel by a Florida manatee to the Mexican Caribbean,” was published this year in the scientific journal Ethology, Ecology & Evolution with a first author from Universidad Quintana Roo. Between November 2020 and February 2021, this manatee was observed in Mexican Caribbean waters between the coasts of Cancun and Isla Mujeres and monitored by the Quintana Roo Marine Mammal Stranding Network. The sighting sparked discussion between Mexican and U.S. scientists because the manatee behaved and looked more like a Florida manatee (the U.S.-dwelling subspecies of West Indian manatees) than an Antillean manatee (the Caribbean subspecies). U.S. scientists identified the manatee using photo ID records in the Manatee Individual Photo-identification System (MIPS), a cooperative effort among U.S. Geological Survey (USGS), FWC and Mote that had observed the animal on Florida’s east coast for 14 years.
Finding a Florida manatee in this part of the Mexican Caribbean, which hosts small numbers of the Antillean subspecies, is one important hint that conservation strategies should be coordinated across national boundaries; the report authors suggest expanding photo ID efforts in the Caribbean region.
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Launched exciting new efforts to study manatee vocalizations—the squeaks, squeals and other sounds manatees make, which can be recorded to provide valuable data for managing and conserving populations. This year, Mote Postdoctoral Research Fellow Dr. Beth Brady joined our team to add more acoustic science to the manatee conservation toolbox. To assess how manatees are doing, natural resource managers rely strongly upon visual surveys. In Florida, Mote is a critical partner in state and federal manatee monitoring efforts including aerial (airplane) manatee counts and boat-based photo-ID surveys that have documented some individual manatees for decades. However, in other areas where manatees’ habits are unknown or where manatees are skittish due to poaching, visual surveys are tougher and sound may provide a valuable alternative.
First, scientists need a clear understanding of what sounds manatees can make. Past studies have suggested Florida manatees make two to six types of calls. A new study led by Brady during her time at Florida Atlantic University and published in 2020 in The Journal of the Acoustical Society of America yielded a clearer answer based on a much larger sample of wild manatee recordings—1,114 calls from three habitats—and increasingly sophisticated statistical analyses. The results: Florida manatees make five call types—squeaks, high squeaks, squeals, squeak-squeals, and chirps—but that’s not all. The study confirmed that manatees have “graded” calls, meaning they can adjust a single call to convey more nuances of what they’re doing or how they’re feeling. Think of how a cat adjusts its “meow” when startled, happy, excited, or when encountering another animal.
This year, Brady co-authored the first peer-reviewed paper describing African manatee vocalizations. The study, “First characterization of vocalizations and passive acoustic monitoring of the vulnerable African manatee (Trichechus senegalensis),” was published this year in The Journal of the Acoustical Society of America. Results suggest that acoustics could be a useful tool for detecting these little understood, elusive and imperiled animals.
Mote and partners in Mexico are investigating how manatees respond to recorded sounds from other manatees, focusing on Antillean manatees. Similar playback sessions are planned for Hugh and Buffett, the two Florida manatees at Mote Aquarium who are renowned for their high level of training that allows them to participate in studies beneficial to their species. The manatees’ responses can help reveal which calls are biologically significant. Antillean and Florida manatees are the two subspecies of West Indian manatees, a species considered vulnerable to extinction by the International Union for Conservation of Nature (IUCN).
Exciting new Mote research also focuses on the sounds manatees can make at different life stages—this ongoing research is beginning to suggest that manatee calves (babies) may have a distinct call. -
Co-authored a peer-reviewed paper helping to fill data gaps on Florida manatee population dynamics over the past 20 years, which could help with estimating their abundance in between surveys, better understanding how likely young manatees are to survive, clarifying how events like red tides and severe cold weather might have affected the population. The paper, “Reconstructing population dynamics of a threatened marine mammal using multiple data sets,” with a first author from the U.S. Fish and Wildlife Service, was published this year in Scientific Reports, a journal from the publishers of the prestigious Nature. The study offers a new “integrated population model” designed to make the most of our existing data and help us better estimate and infer how manatee populations fared in the past. Such efforts can help better predict how current and future changes—for example, environmental shifts or declines—could affect manatees presently or in the future.
Read more from FWC: https://myfwc.com/research/manatee/research/population-monitoring/ipm/
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Mote scientists educated the public about manatees and Mote’s mission through an educational display at the Manatee Observation and Education Center in Fort Pierce, Florida. The display was featured for three months, visible to the 7,475 people who visited the Center.
A tale of two Alaskan polar bear populations
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80 polar bears were sampled to investigate the environmental contaminants in their bodies, through a partnership effort among Alaska’s North Slope Borough, Mote Marine Laboratory and the U.S. Geological Survey. Thanks to this significant collection of samples (a small amount of blubber and serum from most bears), the scientists are learning the Chukchi/Bering Sea stock of polar bears have accumulated d a different profile of environmental contaminants than the Southern Beaufort Sea stock. This is vital information because different contaminants can produce different health impacts, and wildlife managers need to know the specific threats to each group of bears to protect this threatened species.
The Chukchi/Bering Sea stock and Southern Beaufort Sea stock are the two distinct polar bear groups of Alaska’s coastal-marine ecosystem. Both face increasing challenges from climate change along with persistent organic pollutants, chemicals from industry and fossil fuels in other parts of the world that are often transported in the atmosphere and deposited in the Arctic.
Which contaminants the bears encounter could change due to many variables. For example: Some contaminant types are becoming more common and others are declining; climate change can affect weather patterns and reduce sea ice, potentially affecting how contaminants move in the environment; with less sea ice, polar bears may be feeding on more land-based prey—and changes in diet can change their contaminant exposure and their body condition.
Native Alaskan residents and visiting scientists have seen changes in polar bears’ distribution and body condition in recent years, and research to date has suggested that the two bear stocks may differ in their abundance and health—with the Chukchi/Bearing Sea stock possibly healthier than the Beaufort Sea stock.
The Mote project team focused on analyzing the bears’ lipids—molecules that form fatty tissues and other important components of animals’ bodies but also tend to harbor persistent organic pollutants absorbed from the environment. As the team suspected, the two groups did have differences in their lipid profiles and their contaminants. The researchers are currently analyzing the potential relationship between the two and interpreting their findings in light of past studies and Mote’s new research on how specific contaminants may affect polar bear health.
To better understand how organic contaminants affect polar bear immune systems, this year Mote scientists cultured blood cells sampled from bears at San Diego Zoo and challenged those cells with contaminants that have been found in wild bears. Serum collected from bears were then evaluated for indications of change in immune function and reproduction.
Mote scientists expect to complete their analyses and detail their specific findings in 2022—including bears’ levels of major classes of contaminants, their body condition and potentially their vulnerability to disease—to benefit the management of polar bears.
The project was supported by the Joint Baseline Studies Program, North Slope Borough and Shell Oil Company.
Serving as dolphin detectives
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A record 22 dolphin calves were documented in 2021 by the Sarasota Dolphin Research Program (SDRP), a Chicago Zoological Society Program in collaboration with Mote Marine Laboratory. This exceeds the record of 21 set in 2017. SDRP leads the world’s longest-running study of a wild dolphin population, focused on the long-term resident bottlenose dolphins of Sarasota Bay, Florida. While a baby boom is an exciting indicator of the dolphin community’s health, SDRP’s long-term research has allowed them to investigate more deeply.
During and after the 2018-19 bloom of Florida red tide along southwest Florida, there were more deaths of dependent dolphin calves—juveniles still relying on their mothers—than SDRP usually observes. In 2019 and 2020, SDRP also documented that record numbers of Sarasota Bay dolphins were bitten by sharks and that one important prey item for sharks—stingrays—were far less abundant than expected.
These findings could indicate that sharks preyed on dolphins more often when their typical prey were less available. Past SDRP research has also shown that young dolphin calves are likelier to disappear when fewer rays are found in SDRP’s long-term fish surveys.
Since Sarasota dolphins typically rear their young for about four years, the loss of dependent calves before that age during and following the red tide meant that more females were available to reproduce in 2020, contributing to the increase in the number of births this year, after a 12.5 month gestation period.
https://sarasotadolphin.org/2021-baby-boom/
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The SDRP team is conducting monthly photo-identification surveys to document bottlenose dolphins in the vicinity of the Piney Point wastewater spill, a release of 215 million gallons of nutrient-laden wastewater in spring 2021 through Port Manatee in southeastern Tampa Bay. These monthly surveys will continue through April 2022 to help the researchers account for any seasonal variation in the dolphin community. Preliminary data showed few sightings in April and May 2021—about three sightings and eight dolphins per survey on average—in areas where SDRP’s past surveys in 1988-1993 found dolphins to be more common. Fortunately, those dolphins showed no obvious respiratory or other health issues. By June 2021, after the wastewater had largely dispersed, the monthly average increased to 10 sightings and 48 dolphins per survey. Those numbers declined again as a severe bloom of Florida red tide affected the area, seemingly exacerbated by the spill.
This study is ongoing and more data must be collected and analyzed to determine if the changing dolphin numbers might have been associated with the spill, the red tide, or other environmental or seasonal conditions.