Research

Project Limulus was started in 1998 and has since conducted multiple studies focusing on the life history of the American horseshoe crab population living within Long Island Sound (LIS). Some studies include:

1.  Since 1998 Project Limulus has been conducting a tag and recapture analysis of adult horseshoe crabs movement patterns within LIS. Cinch tagging was original used, but has been replaced by white disc tags (see pictures below). The tag and recapture study was designed to answer the following questions:

  • Do horseshoe crabs come back to the same beach every year to mate?
  • What are the spawning population trends; are horseshoe crab numbers increasing, decreasing or stable within LIS (Long Island Sound)?
  • What is the sex ratio of adult males to females?
  • What are the average carapace (prosoma) sizes for males and females?
  • What are the average ages of crabs living within LIS (shell condition/age estimation)
  • Do tags harm the horseshoe crabs? 

Mattei J.H., M.A. Beekey, A. Woronik, H. Potter, C. Bond, K. Smith. 2011. Estimation of short-term tag mortality in the American horseshoe crab, Limulus polyphemus. Transactions of the American Fisheries Society 140:(4) 954-958.  >>Download article

Mattei, J. and M. Beekey. 2008. The Horseshoe Crab Conundrum. In: Wrack Lines 8:1, Spring/Summer 2008, CT Sea Grant.  >>Download article


2.  Investigations of the connection between shore birds along the LIS coast and horseshoe crab eggs. By conducting an experiment using predatory exclusion cages and visual monitoring Project Limulus set to answer the following questions:

  • Do shorebirds living along LIS rely on horseshoe crab eggs for food in the same way as shorebirds residing within Delaware Bay do?
  • Does the density of spawning horseshoe crabs play an important role in their interaction with other species?

Beekey, M.A., J.H. Mattei and B.J. Pierce. 2013. Horseshoe crab eggs: A rare resource for predators in Long Island Sound. Journal of Experimental Marine Biology and Ecology 439:152-159.


3.  The genetics of the population living with LIS was investigated by taking DNA samples from 5 beaches bordering LIS, PCR and genetic analysis was used to answer the following questions:

  • Is there one large interbreeding population within the Sound or are there subpopulation populations separated and living in different embayments?
  • Do horseshoe crabs in LIS share similar genetic traits as their counterparts in Delaware Bay?
  • Is the horseshoe crab population in LIS suffering from inbreeding depression?

Kasinak, J., K. Bartholomew, M.A. Beekey and J.H.Mattei. 2011. Movement Patterns and Population Genetics of the American Horseshoe Crab in Relation to Long Island Sound Conservation Strategies. Proceedings of the 2010 Biennial Long Island Sound Research Conference. University of Connecticut, Stamford, CT.


4.  Movement patterns and mating behavior was examined using the tag and recapture study as well as sonar tagging.

  • Do horseshoe crabs come back to the same beach every year to spawn?
  • Do horseshoe crabs within LIS move from 1 beach to another within a single spawning season?
  • Within multiple years?
  • Do horseshoe crabs in Connecticut cross the Sound and spawn on beaches in New York?
  • Do horseshoe crabs exhibit polygamy in the form of large mating clusters as those in Delaware Bay with multiple males with a single female?

Mattei, J.H., M.A. Beekey, A. Rudman, A. Woronik. 2010. Reproductive behavior in horseshoe crabs: does density matter? Current Zoology 56(5):634-642.  >>Download article

Beekey M.A. and J.H. Mattei. 2008. What long term mark/recapture studies reveal about horseshoe crab population dynamics in Long Island Sound. Proceedings of the 9th Biennial Long Island Sound Research Conference. Connecticut College, Groton, CT.


5.  Determining where juvenile horseshoe crabs grow and develop within LIS. Project Limulus set out to determine:

  • Where juvenile horseshoe crabs spend their time before becoming adults and how many size classes live in the same habitat.


6.  Investigating the possible impacts of physical beach characteristics and morphology on horseshoe crab site selection for spawning.

  • Do horseshoe crabs prefer a strict set of beach characteristics that determine what beaches are more likely to have spawning horseshoe crabs?
  • Do beach slope, grain size and wave action have impacts on where horseshoe crabs tend to spawn?