Florida Horseshoe Crab Watch: Linked with Limulus Spring 2017 Citizen Science sampling season

We depend on our volunteers

This past spring sampling season (Mar-April 2017) marks the 3rd formal round of nesting surveys and tagging by citizen scientists on Cedar Key beaches. One volunteer reported that they thought this was the most successful season yet, and we would tend to agree!

"Why?", you might ask. Well, the Florida Horseshoe Crab Watch coordinator team is excited about the direction of this program for many reasons.

For one, the program is growing, and fast! This survey season was the first season for Hagen's Cove (near Steinhatchee) and Shired Island (near Horseshoe Beach). In addition, groups in Volusia County and Nassau County are starting up new programs on Florida's east coast. And the number of volunteers in the program has grown, too, up from 20 active volunteers last sampling season to over 47 active citizen volunteers this spring. This wonderful, dedicated volunteer corps donated over 820 total hours of time and traveled a total of 15,038 miles to complete the surveys this spring!

We plan to continue to grow the program in the coming sampling seasons and we are so thrilled about the enthusiasm for the program statewide! We are excited by the high quality of data collected by our volunteers, and the public education value of our volunteers' efforts.

All of the volunteers in the program agreed to some degree that they considered themselves stewards of horseshoe crabs - and the numbers don't lie! This past sampling season alone, our citizen scientists went above and beyond their basic data collection duties. Our volunteers educated at least 1,764 people about horseshoe crabs. Most of these educational opportunities arise when volunteers are walking the beach on their surveys and are approached by curious beachgoers. Many have also told their friends about the program!

A nesting pair of horseshoe crabs in Cedar Key

A tag is applied to a female horseshoe crab

Citizen Scientists Collect High Quality Data

This Spring, volunteers completed 12 simultaneous sampling events at 9 different sites, for a total of 108 surveys. Simultaneous sampling across such a large geographic area would be impossible without the help of volunteer citizen scientists. The Florida Fish and Wildlife Conservation Commission is dedicated to collecting data on horseshoe crab nesting, but does not have anywhere near enough staff to achieve the high level of data collection the volunteers are able to complete.

This spring, volunteers observed a total of 2,333 horseshoe crabs on the 9 nesting beaches. As in previous sampling seasons, there were more males (1,559) observed than females (774) on the nesting beaches. The highest number observed in any one survey was 644 crabs at Cull Preserve in Cedar Key on 3/31/2017. Cull Preserve also had the 2nd and 3rd highest total number observed on the two days prior (3/29/2017 - 349 crabs, 3/30/2017 - 323 crabs).

Number of total horseshoe crabs observed on Nature Coast nesting beaches in spring 2017
Total number of female (grey bar) and male (orange bar) horseshoe crabs observed on Nature Coast nesting beaches in spring 2017

Of these, volunteers collected, tagged, and released 373 total crabs. Out of these, 25 tagged individuals were seen again (resighted). This tag resighting rate of 6.7% is lower than the fall 2016 season, where approximately 11% of tagged crabs were resighted. However, we still got excellent data from the tagging effort!

Resightings of tagged horseshoe crabs are extremely important - any time you see a tagged horseshoe crab, please make a note of the number, date, and location and report the sighting!

Tagging data from 2016 suggested that horseshoe crabs move a good deal more among nesting beaches than previously thought, and the spring 2017 data seems to offer more evidence of this. This spring, 16 crabs were resighted on a different beach than the one where they were tagged vs. only 8 that were resighted on the same beach! This year, we had two female crabs that were tagged at Shired Island, and resighted just two days later at Cull Preserve in Cedar Key!! Information of this kind is extremely valuable for helping researchers understand population connectivity across nesting areas - and it was all collected thanks to citizen scientists!

Citizen scientists take data on a crab before tagging.

Volunteers: have a look at the table above to find out the origin and destination of crabs you tagged or resighted!

Stay tuned for more!

Florida Horseshoe Crab Watch will continue in Fall 2017, and may be coming to a beach near you! Email savanna.barry@ufl.edu or tiffany.black@myFWC.com if you want more information about how to get involved in Florida Horseshoe Crab Watch.

Bonus: Trilobite larva hatching out on Seahorse Key - photos courtesy of Debbie and John Goad.

Photos of the larvae of horseshoe crabs, called trilobites, hatching out of a nest on Seahorse Key. Photos: Debbie and John Goad
Florida Horseshoe Crab Watch is a collaboration between the University of Florida and the Florida Fish and Wildlife Conservation Commission.


Savanna Barry, UF IFAS (Tyler Jones), Debbie Goad, John Goad, Emma Pistole

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