Horseshoe crabs rely on estuaries for food resources, places to spawn and for larvae and juveniles to develop and grow. Many of these estuaries are becoming increasingly urbanized and dominated by human activity. An urban estuary is characterized by armored shorelines, high nutrient loads, large fluctuations in algal and bacteria populations, increased levels of pollutants like heavy metals and pesticides, and seasonally low oxygen levels and pH. While urban estuaries are challenging for horseshoe crab survival and to researchers trying to study them, there are also opportunities for involving the public in research and increasing public awareness of the importance of the conservation and survival of horseshoe crabs. Two recent studies in New York and Connecticut have involved citizen scientists to tag and gather valuable data on horseshoe crab population dynamics. It has been discovered that there is very low recruitment of new adults into the two urban estuaries studied and that spawning populations of horseshoe crabs are relatively low when compared to less disturbed more rural estuaries.
Mattei, J., Botton, M.L., Beekey, M., & Colón, C.P. (2015). Horseshoe crab research in urban estuaries: Challenges and opportunities. In R.H.Carmichael, M.L. Botton, P.K.S. Shin, & S.G. Cheung (Eds.). Changing global perspectives on horseshoe crab biology, conservation and management(pp. 537-555). Cham; New York: Springer. doi: 10.1007/978-3-319-19542-1_31