Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Deployments
• Project Information
• Funding

This field experiment was conducted on artificial patch reefs to test for presence of density dependence in invasive red lionfish recruitment, immigration, loss, and growth (in mass and length).  The experiment used 10 reefs which were manipulated so that 4 reefs had 0 lionfish on them (controls), and 6 each had a unique density of lionfish.  Each week, the number of lionfish on each reef was recorded, and new lionfish recruits and immigrants were removed.  Every two weeks, lionfish growth in length was re-measured.  At the end of the experiment (6 weeks), lionfish growth in mass was re-measured. 

Related Manuscript: Benkwitt, C.E. (2013) and Benkwitt, C.E. (2015)

Field experiment on artificial patch reefs to test for effects of  invasive red lionfish density on native coral-reef fishes. Four reefs were used as 0-lionfish control reefs and there was one reef per remaining lionfish treatment (2, 4, 6, 8, 10, and 12 lionfish/m²). Using SCUBA and handnets, we collected lionfish ranging in initial size from 40 to 71mm total length [TL] from nearby reefs.  Each lionfish was given a unique elastomer tag (Northwest Marine Technology Inc., Shaw Island, WA, USA) to differentiate between lionfish at the start of the experiment and any new immigrants over the course of the study and to monitor demographic rates as part of another study (see related files and references). Treatments were started on all reefs within a 2-week period. To maintain treatments, we monitored lionfish density during weekly visits and removed any new lionfish recruits (total of 15 throughout experiment) and immigrants (total of 5 throughout experiment). In addition, we removed resident native piscivores and standardized the number of Nassau grouper (Epinephelus striatus) and territorial damselfishes (Stegastes spp.) weekly to mitigate any confounding effects of these strong interactors on fish recruitment. Of the lionfish initially placed on the reefs, only 6 out of 40 disappeared. To account for the small changes in lionfish density throughout the experiment, we averaged the weekly lionfish densities on each reef over the course of the experiment (1, 2, 4, 7, 10, and 12 lionfish/m^2).

Following the establishment of lionfish density treatments, a pair of divers using SCUBA censused the entire fish community on each reef weekly for 7 weeks, recording the species, abundance, and body size (TL estimated to the nearest centimeter) of all fish present both on the reefs and within a 1-m radius around the reefs. Divers slowly approached the reefs and first counted all planktivorous and active species hovering above the reefs from a distance of approximately 3 m. From a distance of 1 m, the divers slowly circled the reefs and counted all other species, using dive lights to count cryptic species in holes.

All data were entered by one person, and then subsequently checked by another person to ensure accuracy.  

No processing was done. 

DMO Notes:

-reformatted column names to comply with BCO-DMO standards
-replaced all spaces with "_"
-replaced all blank cells with "nd"

The Pacific red lionfish (Pterois volitans), a popular aquarium fish, was introduced to the Atlantic Ocean in the vicinity of Florida in the late 20th century. Voraciously consuming small native coral-reef fishes, including the juveniles of fisheries and ecologically important species, the invader has undergone a population explosion that now ranges from the U.S. southeastern seaboard to the Gulf of Mexico and across the greater Caribbean region. The PI's past research determined that invasive lionfish (1) have escaped their natural enemies in the Pacific (lionfish are much less abundant in their native range); (2) are not yet controlled by Atlantic predators, competitors, or parasites; (3) have strong negative effects on populations of native Atlantic fishes; and (4) locally reduce the diversity (number of species) of native fishes. The lionfish invasion has been recognized as one of the major conservation threats worldwide.

The Bahamas support the highest abundances of invasive lionfish globally. This system thus provides an unprecedented opportunity to understand the direct and indirect effects of a major invader on a diverse community, as well as the underlying causative mechanisms. The PI will focus on five related questions: (1) How does long-term predation by lionfish alter the structure of native reef-fish communities? (2) How does lionfish predation destabilize native prey population dynamics, possibly causing local extinctions? (3) Is there a lionfish-herbivore-seaweed trophic cascade on invaded reefs? (4) How do lionfish modify cleaning mutualisms on invaded reefs? (5) Are lionfish reaching densities where natural population limits are evident?