Connectivity of Tropical Marine Ecosystems: Understanding Biodiversity and Trophic Relationships in the Virgin Islands and Puerto Rico

Science Center Objects

Marine reserves and protected areas in the U.S. Virgin Islands and Puerto Rico encompass a variety of tropical ecosystems, including coral reefs, mangroves, and seagrass beds, but questions remain regarding how effective these areas are at preserving and protecting the habitats and species they encompass. USGS and collaborators address this question by examining the biodiversity and food web dynamics of the fish and invertebrates that reside in connected tropical ecosystems. 

Tropical ecosystems, including coral reefs, mangroves, and seagrass beds

Tropical ecosystems, including coral reefs, mangroves, and seagrass beds, can be found in the U.S. Virgin Islands 

The Science Issue and Relevance: Marine reserves and protected areas surrounding the Virgin Islands and Puerto Rico contain a variety of tropical biomes, including coral reefs, mangroves, and seagrass beds. These ecosystems preserve nursery habitats for native fishes, support biodiversity of a full complement of aquatic invertebrates, and reduce effects associated with pollution and island land use. In order to answer questions regarding how effective these designated areas are in preserving and protecting these spatially connected habitats and associated fishes and invertebrates, collaborative interdisciplinary research has begun in the Virgin Islands and Puerto Rico. Thus, the biodiversity and trophic dynamics of fishes and invertebrates residing in connected mangroves, seagrasses, and coral-reefs are being examined to discern the effectiveness of current marine reserves and protected areas for conserving reef resources.

Methodology for Addressing the Issue: To address the issues of connectivity, trophic relationships and biodiversity, various approaches were used for collecting samples during the summer from 2008-2013. Telemetry and stable isotope analyses (SIA) were used to track fish movement patterns in and out of connected habitats, marine reserves and protected areas, and to identify invertebrates within fish foraging habitats. Trophic relationships between fishes and their prey were characterized by identifying fish stomach contents and conducting SIA of fishes, invertebrates, and primary producers (e.g., algae and plants). Laboratory-based parasite feeding experiments were conducted in a closed saltwater research system to understand stable isotope tissue turnover rates in fish hosts in a controlled environment. The laboratory-based data will be used as a foundation for future parasite and fish stable isotope studies. DNA barcoding (a taxonomic method that uses genetic material to identify an organism to species), in conjunction with traditional morphology-based identification is being used to assist taxonomic identification and understanding of the diversity within habitats. Additionally, DNA barcoding will help to identify marine organisms in fish stomachs, thus providing data on prey consumed by reef fishes.

A variety of methods were utilized to collect samples

A variety of methods were used to collect samples

Future Steps: Data processing and analysis are currently underway to provide information on the trophic relationships and habitat use by various fauna, as well as the tissue stable isotope turnover rates from the dietary studies.  Understanding the complex biological interactions among transient and resident fish and invertebrates will be helpful in management of both protected species and those of economic importance. These data will help in the evaluation of the effectiveness of marine reserves and protected areas in the Virgin Islands and Puerto Rico, important unincorporated territories of the United States. This information is of use to several partner agencies, including the National Park Service and NOAA.