A new NCCOS study finds biodiversity in a U.S. Virgin Islands mangrove bay is 30-50% lower than 25 years ago.

With partners from the Virgin Islands Department of Planning and Natural Resources, NOAA’s Coral Reef Conservation Program, and the U.S. National Park Service, NCCOS resampled juvenile fishes in mangrove habitats of a Caribbean estuary using the same methods as a study conducted 25 years ago.

NCCOS and partners compared assemblages of juvenile fishes in the mangroves of Salt River Bay National Historical Park and Ecological Preserve on the island of St. Croix from 1991 to 1993 and 2018 to 2019 using trap collections to quantify changes. Although the environmental and physical properties of the mangrove landscape were similar between the two periods, there were significant changes in many aspects of the fish assemblage.

The observed changes in the fish assemblage may be due to natural variations in recruitment, environmental influences, and/or hurricane disturbance, but for some species relate best to declines in adult reef fish populations in the region.

Views of Salt River Bay, USVI. Credit US NPS

The prop roots of mangroves play an important role as habitat for juvenile fishes. Resampling studies (>10 years apart) are rare and provide valuable insights into the structure and stability of these systems in the face of escalating pressure from coastal development, climate change, and fisheries.

Results will contribute to a watershed management plan, long term monitoring and support protection of the remaining mangrove stands in St. Croix for maintaining productive and diverse fish populations.

Red mangrove habitat. Credit. University of Puerto Rico.

The results are published in the Bulletin of Marine Science.

Citation: Kendall, Matthew S., Bethany L Williams, Ashley Ruffo, Arliss J Winship, Laughlin Siceloff, Aaron Adams and William Tobias. 2020. Resampling 25 years later reveals fewer species but higher abundance of juvenile fishes in a Caribbean mangrove bay. Bulletin of Marine Science. https://doi.org/10.5343/bms.2020.0005