We undertook an ecological assessment of bank systems in the Florida Keys National Marine Sanctuary (FKNMS) to determine what will be lost if these systems continue to be degraded by high boat traffic. The species composition, high density and diversity of the fish assemblage indicate bank systems provide a key structural component supporting the biodiversity and productivity of the FKNMS. We recommend consideration of this critical habitat for Sanctuary Preservation Area (SPA) status.
Why We Care
The coral reefs of the Florida Keys National Marine Sanctuary (FKNMS) are recognized as a national treasure whose resources support a fishing and tourism industry valued in billions of dollars per year. Included in this local ecosystem are bank systems. These systems were formed approximately 2000 years ago from coral rubble and sand and are currently degraded by high boat traffic. Their fragmentation and erosion may unbalance the local ecosystem and threaten Florida’s coral reefs.
What We Did
We undertook an ecological assessment of three bank systems (Moser Channel, Bamboo, and Channel Key Banks) in the Florida Keys National Marine Sanctuary (FKNMS) by monitoring fish and sea floor (benthic) communities.
This revealed that bank systems are ubiquitous and provide a mosaic of essential fish habitat, such as juvenile nurseries, and foraging and sheltering grounds for adult fishes. Their physical complexity provides protection for a high diversity of plants, algae, invertebrates, fish, crustaceans, etc.
Many of the fish species that we observed in bank systems were also found on coral reefs. The individuals around the banks systems are generally younger, while those on reefs are adults. This suggests as these species get older (and larger) they "graduate" from bank systems and move onto coral reef habitats as adults. If this is true (as the physical proximity of bank systems to coral reefs suggests is likely), then bank systems serve as a source of fishes for coral reefs. Destruction or degradation of banks would be expected to reduce the number of adult fishes that migrate to coral reefs. Sampling showed that geographically distinct systems along the Keys consistently attract fishes, including a variety of commercially important species. The bulk of the animals and plants associated with these systems consist of bottom dwelling carnivores that feed nocturnally in the basins surrounding bank systems. The fish species composition and their close proximity to the coastal ocean indicates bank systems provide stepping stones for reef species that spawn in Florida Bay and the coral reefs of the coastal ocean.
We will work on a comprehensive inventory of the bank systems within the Florida Keys National Marine Sanctuary. While the importance of bank systems to breeding success of reef fishes is apparent, hard numbers of the contribution to fished stocks could provide an economic basis for any protection actions. This will simultaneously promote a better understanding of the role of bank systems in the coral reef ecosystem.