Remembering Dr. Daniel E. Canfield, Jr
A legacy of research and mentorship in Floridian limnology
Coordinated by Gretchen Lescord (LAKEWATCH director) and her staff, with meaningful contributions from many colleagues, volunteers, and friends across the aquatic science community. A special thanks to Mark Hoyer for his assistance with this article.
It is with great sadness that we share the news of Dr. Daniel E. Canfield, Jr. passing on November 3, 2024. Dan was the founder of Florida LAKEWATCH, which has grown to be one of the largest and longest running volunteer water quality monitoring programs in the country. It is impossible to summarize all of Dan’s many achievements in this short article, but we highlight a few below, alongside reflections of Dan’s many colleagues and friends.
Dan was a faculty member in Fisheries and Aquatic Sciences (FAS), part of the School of Forest, Fisheries, and Geomatics Sciences (SFFGS) at the University of Florida (UF) and the Institute of Food and Agricultural Services for 45 years. He will be remembered for his many contributions to the aquatic sciences, including authoring/coauthoring over 125 peer reviewed articles, four books, and countless extension articles/reports in various fields of aquatic sciences. He worked locally, statewide, nationally, and internationally. At his core, Dan was an applied limnologist and was an active supporter of both the North American Lake Management Society (NALMS) and the Florida Lakes Management Society (FLMS). Dan won NALMS’ highest award, the Secchi Disk award in 1995, and FLMS initiated the “The Dr. Daniel E. Canfield, Jr. Volunteerism Award” in 2016 in recognition of his significant contributions to the field of participatory science and water management.
Together we studied streams, lakes and estuaries, primarily focusing on how the flora and fauna are related to background nutrients based on Florida’s geology and physiographic regions. The solid background of Florida limnology that Dan established will be a foundation of aquatic research in Florida for many decades.
-Mark Hoyer, retired director Florida LAKEWATCH, past president of NALMS
Dan Canfield helped me in so many ways early in my career here in Florida. He provided data sets that we worked on together with graduate students, and helped me learn the ropes of management and conservation efforts around the state. Although we certainly did not always agree, he was a true pioneer in our field who genuinely wanted to help others.
-Mike Allen, SFFGS professor and director of UF/IFAS Nature Coast Biological Station (NCBS)
He was also a strong “people person.” He freely shared his data with other scientists so they could use it in their studies. He learned the names of the people that cleaned the offices and mowed the lawns and treated them with respect…
-Roger Bachmann, visiting professor at UF, and Dan’s PhD supervisor and longtime colleague
In 1986, Dan started the Florida LAKEWATCH program, with help from colleagues Sandy Fisher and Mark Hoyer (whom Dan’s younger son is named after). The resulting long-term data on thousands of lakes, rivers, and estuaries by the program’s volunteers are invaluable, and will be used by many management and research professionals locally, statewide, nationally and internationally for decades to come. Additionally, the resulting research and extension information on lake management have enabled many stakeholders across Florida to establish sound lake management plans, which was one of Dan’s underlying goals.
As a past long-time volunteer, I would just like to say that we all owe Dr. Canfield a huge thank you for founding Florida LAKEWATCH. He made a great difference to us all.
-Virginia Densmore, LAKEWATCH volunteer, Lake Blue Heron
The LAKEWATCH program is a shining star of Florida limnology and citizen science in general, and an enduring legacy of his leadership and commitment.
-Evelyn Gaiser, Endowed George Barley Eminent Scholars Chair & Distinguished Professor, Florida International University
With his guidance, I adopted his approach to establish the Lee County Hyacinth Control District, Pond Watch Program. We were incredibly fortunate to have him as a mentor and teacher, helping us apply what we learned and pass it on to the next generation of lake and pond watchers. His dedication to volunteerism and water monitoring has left a lasting legacy. Thank you, Dan, for inspiring and teaching us all.
-Ernesto Lasso de la Vega, Lee County Hyacinth Control District, Pond Watch Program
While his research impact is well known, teaching and mentorship brought Dan the greatest professional joy. Over his career, he supervised over 45 graduate students, many of whom have been successful in areas of limnology/lake management, including with the LAKEWATCH program (i.e., regional coordinator Dan Willis, retired lab manager Christy Horsburgh, data manager Marina Schwartz, and many others) and the state agencies like the Florida Fish and Wildlife Conservation Commission (FWC). During his time at UF he also taught approximately 20 undergraduate students every year in the Introduction to Freshwater Fisheries class, alongside his longtime colleague, Dr. Chuck Cichra. Both Drs. Canfield and Cichra mentored the new LAKEWATCH director, Dr. Lescord, in taking over this course and continuing the longstanding tradition of teaching within the LAKEWATCH program.
He was a talented scientist and extraordinary teacher that mentored me and many other biologists with FWC. He challenged his students and colleagues to think critically and to be innovative.
-Jason Dotson, Subsection Leader, Freshwater Fisheries Research, FWRI & FWC
Later in undergrad I had Dr. Cichra and Canfield in a fisheries course which was one of my favorites. Learning hands on experience with equipment and sampling techniques, important trophic and limnological concepts and again hearing fun stories from both.
-Mike Sipos, Florida Sea Grant Agent, UF/IFAS Extension Collier County
Left: Dan taking students electrofishing (date unknown, LAKEWATCH).
Dr. Canfield made a big impression on me when I took his course. His teaching style was different than what I was exposed to up to that point, and he inspired me by challenging the accepted norms, advocating for the data instead of the cause, and more importantly, by believing in me. Over the course of my professional career, I often sought his counsel on personal and professional issues, and he was always eager to listen and provide a perspective I usually hadn’t considered.
Eric Nagid, Subsection Leader, Freshwater Fisheries Research, FWRI & FWC
Right: Dan more recently talking to students at Lake Alice during a fisheries field lab (date unknown, shared by Chuck Cichra).
Dan also loved teaching young kids, which he thought of as the “future of limnology.” In 1990, he started another program called Fishing for Success, which introduced kids to the basics of aquatic science through catching fish in ponds at UF. The program is still going strong and hosts around 7,000 children each year. More information can be found at https://ffgs.ifas.ufl.edu/extension/fishing-for-success/.
We did go up to LAKEWATCH in Gainesville to see how the samples were handled, and Dan was a great teacher. If I am remembering correctly, one time we went up to LAKEWATCH Dan had [a] bunch of young kids fishing around the pond...
Sandra Andry, LAKEWATCH volunteer, Rodman Reservoir
Left: A recent photo of children at Fishing for Success (FFS), netting aquatic invertebrates, in 2024. Photo supplied by current FFS lead, Bethan Gillett.
Dan is survived by his two sons, Daniel and Mark Canfield, his brother, Tim Canfield, and his sister, Linda Blick, all of whom have our heartfelt condolences for this loss. We also acknowledge that many of our readers knew Dan well and considered him a friend as well as a colleague. We echo the sentiment that many of you shared over the past month: Dan will be greatly missed. Looking ahead, we are committed to continuing Dan’s legacy within the Florida LAKEWATCH program. We will specifically work to emulate his dedication to impactful research grounded in robust data, and his admirable passion for mentoring students in practical skills and core limnological principles.
His approach to parenting and teaching shared some wonderful similarities. He did everything he could to allow us to pursue our dreams while occasionally challenging us with skepticism to examine our futures critically. Below his gruff exterior was the most kind, loving man who wanted the best for his sons and us all. After almost losing him to a mystery illness in the 1990’s that left him disabled, he persevered, and I am lucky to have shared nearly three more decades with him. He was the best father I could have ever asked for. It warms my heart to know that so many of you experienced his love and mentorship I cherished so much.
-Daniel Canfield (Dan's son)
Dan was known for always wearing a red hat. The photo shows a current LAKEWATCH volunteer with one, at the Hillsborough and Pasco annual meeting in November 2024 (SFFGS).
I hope he’s resting somewhere with a lot of lakes and a lot of fish!
-Mary Stonecipher, retired LAKEWATCH lab manager and chemist
LAKEWATCH at the Florida Lake Management Society meeting
Bonita Springs, FL 2024
In August, our team attended the Florida Lake Management Society (FLMS) meeting in Bonita Springs, FL. As always, we exchanged knowledge about waterbody management, connected with volunteers and managers, and attended workshops on algae identification, invasive species, and data analysis.
Did you know that LAKEWATCH has some of the most dedicated volunteers?
Your commitment to our program is impressive and we want to learn more! We’re going to be sending a survey about your experiences with the LAKEWATCH program and your perspectives on our work. Your results will help us better understand our volunteer’s needs and recruit the next generation of LAKEWATCHers! They will also help us inform other citizen science programs that may struggle to recruit or maintain their volunteers as well.
Experts: Rob Robins & Nick Trippel
At LAKEWATCH, we are often asked about invasive and non-native species and their impacts on Florida waterbodies. In this issue, we feature a column by two fish experts, or ichthyologists, on invasive swamp eels in Florida freshwaters. Our experts are Rob Robins (left), collection manager in the Division of Ichthyology at the Florida Museum, and Nick Trippel (right), Fisheries Biologist at the Florida Fish and Wildlife Conservation Commission (FWC).
More non-native freshwater fish species have been found in Florida than any other state, and at least 51 are reproducing. These introductions and their impacts on Florida’s environment are an ongoing challenge to Florida’s natural resource agencies.
Among the established species are two species of swamp eels from the family Synbranchidae. This family includes 27 species native to Central and South America, Cuba, and vast areas of southeast and East Asia, ranging from temperate to tropical regions. The biology of these predatory fishes is remarkable. In particular, their ability to burrow, breathe atmospheric air, provide parental care for developing young, and to travel overland make them excellent invaders. And despite their elongated and eel-like body (and name!), they are not true eels. Their reduced features, including a fused, ventrally located opercular opening and the absence of fins as adults, can also make species identification challenging, and the Florida Natural History Museum has been working to better understand and classify these eels to support monitoring efforts.
Three distinct populations of Asian Swamp Eel, Monopterus spp., were reported from Florida by Collins et al. in (2002), likely meaning three separate introductions. Originally detected in Manatee County near Tampa, and in Broward and Miami-Dade counties in South Florida, these populations have spread throughout much of the western and southern Florida peninsula. Additionally, the Miami-Dade population, located in Homestead and the C-113 Canal, dispersed south into the C-111 canal system and ultimately into Everglades National Park. Recent studies have demonstrated that these Asian Swamp Eels eat a wide variety of invertebrate and vertebrate prey in Florida. They have particularly caused declines in native populations of crayfish and fish species that are adapted to the short periods of flooding in the Everglades.
Acting in part on information posted to iNaturalist, Florida Wildlife Research Institute (FWRI) biologists began surveying the Winter Park Chain of Lakes in Central Florida for swamp eels in 2023. These efforts resulted in the capture of both juvenile and adult Asian Swamp Eel, Monopterus spp. Because this chain of lakes is connected to the St. Johns River, the colonization of the Central Florida region by swamp eels is a concern.
Swamp eels have been introduced broadly throughout the United States, including across Florida, Georgia, Hawaii, and Delaware. As in Florida, these Monopterus populations likely represent multiple genetically distinct lineages, which could possess varying ecological and life-history traits and thus represent potentially different ecosystem threats. The Gangetic Swamp Eel, Ophichthys cuchia, -- commonly referred to as “Cuchia” -- has also been introduced to New Jersey, Maryland, Pennsylvania, Michigan, New York, and Texas. Therefore, more detailed research is needed on the impact of swamp eels on their invaded environments, as well as on potential mitigation strategies to limit their continued spread.
There are multiple pathways for swamp eels to have made their way to public waterways. Perhaps the most unique is the practice of prayer or ceremonial animal releases. These traditional religious practices, which cross many religious faiths and sects, are considered a method by which believers build spiritual enrichment. The source of animals used in such practice is often live food markets. Specimens bought from Central Florida markets, vouchered at the Florida Museum of Natural History, suggest swamp eels have been consistently available at Central Florida markets for decades.
So, it is perhaps unsurprising that in late 2023, Cuchia was detected by FWRI staff while surveying for Monopterus spp. in Central Florida. Easily distinguished from Monopterus by the presence of scales on the body and a pair of pouches on the side of the head that expand during air breathing, Cuchia appear to have firmly established populations in the region already. Extensive sampling in the latter half of 2024 has detected Cuchia in multiple Central Florida lakes, including the capture of the first juveniles (which suggests the population is reproducing and will grow). These findings support the expansion of swamp eels further north in Florida and highlight the need for more monitoring efforts statewide.
FWRI and Florida Museum staff are working to determine both the extent of the swamp eel invasion across Florida, with an emphasis on Central Florida, and are studying the impacts of the species on native systems. Please report any collections or suspected sighting of these species to Nick.Trippel@myfwc.com. Records of swamp eels and other nonnative fishes based on voucher specimens collected for future study are searchable at https://specifyportal.floridamuseum.ufl.edu/fishes/.
Volunteer Milestones
In our final newsletter of 2024 we want to highlight all of our amazing volunteers who reached major milestones this year! We have a seriously dedicated group of volunteers and could not be more proud of your accomplishments! We have a whopping 51 volunteers reaching 10, 15, 20, 25, and 30 year milestones this year - congratulations!!
Bowfin
Scientific name: Amia calva
Written by Regional Coordinator, Dan Willis
Bowfin are commonly called mudfish or dogfish and have a long elongated stout body with a long dorsal fin that almost reaches the caudal fin (tail fin). They have an olive, mossy green to brown coloration on their back which lightens up on their sides to the belly which can be yellowish to white. Males have an eye spot at the base of the caudal fin. Bowfin, and the closely related Eyespot Bowfin Amia ocellicauda, are the last members of the order Amiiformes and only living members of the family Amiidae. They are sometimes called "living fossils" because they have retained some characteristics of their ancestors, such as the ability to breath air.
They are predatory fish with a large mouth and small sharp teeth. Bowfin have an air bladder that can function like a lung enabling them the ability to gulp air. This gulping ability allows them to live in poorly oxygenated waters. They are usually found in swamps, backwater areas of streams, and lakes that are quiet with less current.
They have been called "trash" fish by many, however, there is a growing group of people that consider them a great game fish (sport fish) to try and catch. The Florida Fish and Wildlife Conservation Commission lists the state record at 19 pounds and the can grow up to lengths around 2-3 ft. They can be caught on topwater plugs, deep water lures, and live bait. Not a prized fish for meat but can be fried, smoked, or made into fish patties. There is no bag or size limit.
- Diet: They like to stalk and ambush prey such as small fish and amphibians. They also eat aquatic invertebrates and aquatic insects.
- Distribution: They are native to central and eastern north America.
- More information: https://myfwc.com/wildlifehabitats/profiles/freshwater/bowfin/
Whistling Duck
Fulvous Whistling-Duck: Dendrocygna bicolor
Black-bellied Whistling-duck: Dendrocygna autumnalis
Written by Florida LAKEWATCH Extension Manager, Liz Moreau
Florida is home to two of the eight species of whistling duck, named for their vocalizations, which sound like high-pitched whistles. The Fulvous Whistling-duck has a chestnut-colored belly and head and dark legs and beak, while the Black-bellied Whistling-duck has a black belly, grey head, and pinkish-red legs and bill. Unlike most duck (and many other bird) species, whistling ducks do not have sexual dimorphism, meaning males and females look alike!
These birds are quite the “odd duck”! Unlike most other waterfowl, they can sometimes be found roosting or nesting in trees – giving them another common name of “tree duck”. They can be found in agricultural lands and near freshwater lakes, ponds, and marshes throughout the state.
Interestingly, both species are relative newcomers to nesting in Florida. Fulvous whistling ducks began nesting in Florida only in the 1950s with the spread of rice farming. Black-bellied whistling ducks are even more recent arrivals – first noted near Sarasota in 1981, their range has expanded significantly with warming temperatures.
Their populations also appear to be growing in Florida, much to the delight of duck hunters who prize these birds as excellent food. The rules and regualtions for hunting whistling ducks can be found through Florida Fish and Wildlife Conservation Commission.
Fulvous Whistling Duck Cornell Lab Range Map
Black-bellied Whistling Duck Cornell Lab Range Map
- Fun fact: Both of Florida’s whistling duck species may mate for life.
- Diet: Both species eat mainly seeds and grains with the occasional aquatic insect or snail.
- Threats: Populations are increasing throughout the US but further development of agricultural lands may reduce habitat availability.
- More Information: FWC, Audubon
Reminders
Who you gonna call?
Make sure you are getting in touch with the right person for you! Regional Coordinators are the support for new and existing volunteers and are usually the first point of contact for the public to ask questions about Florida’s waterbodies. They train and coordinate with volunteers to collect water, help compile the data and disseminate the information back to the volunteers and the general public. There are currently two coordinators Dan Willis and Jason "MO" Bennett and they each serve a specific region of the state. The area and contact information for each Regional Coordinator can be found below. We look forward to assisting you!
Broken Bottles
The LAKEWATCH Lab has been receiving nutrient bottles that are in rough shape. These are the smaller bottles that you fill and freeze each time you sample. We reuse these bottles for as long as possible to save money for the program and keep as many lakes in the program as we can. Please follow the tips below to help us keep using these nutrient bottles:
- Please do not write on the bottles. Make sure to write on the labels only.
- Don't overfill them. The water expands as it freezes and will crack the bottles.
- Be careful when handling frozen bottles as they can crack easily.
Please complete your data sheet!
You work hard for your data so don't forget the little things. Data sheets without sampling and filtering times and dates must be entered with "qualifiers", which means they won't be as useful to DEP and researchers. In fact, they may not be able to be entered into DEP's Watershed Information Network at all.
The LAKEWATCH newsletter is edited by Dr. Liz Moreau. You can reach out with questions, comments, or feedback at duermite@ufl.edu