horse conch

Historical data reveals big changes in a Florida seagrass community

By Valerie Perini

Habitat loss is threatening natural systems worldwide, and coastal areas – heavily impacted by humans – are particularly at risk. Combining historical data with present day observation and experimentation can be a powerful tool to assess the extent and impact of habitat loss. Employing this approach, PhD student Tanya Rogers and Assistant Professor David Kimbro recently conducted a study investigating the impact of habitat loss on biodiversity and species interactions in a northern Florida seagrass community.

In the study, recently published in the journal Marine Ecology Progress Series, Rogers and Kimbro compared data from historical sources and the present day. They found that the focal seagrass bed had decreased in area by 80% due to changes in sediment deposition, and this habitat loss coincided with the disappearance of two species of large predatory snails. The researchers then investigated the impact of these changes in community composition with a field experiment examining feeding interactions within current versus historical food webs.

Their results indicated that the top predator, the horse conch, preyed most heavily on the two species that had disappeared, and that one of these absent species was an important consumer of clams and mussels, the basal resources in the community. These findings illustrate how habitat loss in this community has altered interactions across multiple trophic levels, removing the strongest top-down interactions from this food web. The researchers note that since strong interactions such as these are often unstable, these results may reflect loss of the least stable interactions in response to habitat loss. 

While more research is needed to assess whether strongly-interacting species are indeed most vulnerable to local extinction when faced with habitat loss, this study sheds light on the value of utilizing historical data, and the inherent vulnerability of community dynamics, when faced with threats such as habitat loss.