Table of Contents

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

Behavioral response of invasive lionfish versus native grouper when presented with two congeneric prey fishes (fairy and blackcap basslets) in aquaria.

For related datasets, please visit the project link: https://www.bco-dmo.org/project/561017

We conducted all experimental trials in 50 gallon (ca. 190 l) acrylic aquarium tanks (91.5 × 38 × 51 cm) with continuous flow-through seawater systems. Food was withheld from predators for 24 h prior to observation to ensure predator response to the presence of prey. Tanks were divided in half with a removable central barrier of solid aluminum (Fig. 1). We released a single predator into one side of the tank and placed 2 basslets in the other side. Basslets were held in identical small glass containers (~500 ml) with mesh covers (1 basslet per container) positioned in each corner of the tank. These prey containers ensured that predators were able to receive both visual and chemical cues from basslets, but could neither make physical contact nor consume any basslets.

To determine whether the preference of predators for basslets was driven by basslet species (fairy and blackcap) or basslet size (small and large: 1.7–2.5 and 3.5–5.2 cm TL, respectively) we presented pairs of basslets in cross-factored combinations of the 2 variables, resulting in the following treatments: (1) small fairy and large fairy, (2) small blackcap and large blackcap, (3) small fairy and small blackcap, (4) large fairy and large blackcap, (5) small fairy and large blackcap, and (6) large fairy and small blackcap. In addition to randomizing the order of basslet treatments presented to each predator, we also randomized the corner of the tank basslets were placed in every time a treatment was presented.

Once the predator and basslets were in their respective sides of the tank, we allowed them to acclimate for 20 min, after which we removed the central barrier and observed the predator’s behavior for 10 min. Observations were performed either in person (74 lionfish trials; 73 graysby trials) or filmed with a digital video camera (16 lionfish trials; 17 graysby trials) positioned outside of the tank. During each 10 min trial, we recorded (1) which basslet the predator hunted first (initial hunting preference); (2) the number of times the predator’s mouth made physical contact with each glass container (number of strikes); and (3) the amount of time the predator hunted each basslet (hunting time). We defined the hunting behavior of lionfish as occurring when an individual directly faced a basslet with flared pectoral fins and/or blew pulsed jets of water towards a basslet (Cure et al. 2012). We characterized graysby hunting behavior as occurring when an individual positioned itself near a basslet (<10 cm in this experiment) while directly facing the basslet (Webster 2004).

At the conclusion of the 10 min trial, we separated the predator from the basslets and placed the central barrier back in the tank. A new combination of basslets were placed in the glass containers, and all fish were allowed to acclimate for 20 min before removing the barrier and observing predator response for another 10 min. This procedure was repeated until all 6 basslet treatments had been presented to each predator in random order.

When testing for significant differences in predator response between fairy versus blackcap basslets, we analyzed only the 4 treatments where predators were presented with 2 different basslet species (lionfish: n = 11; graysby: n = 11). Similarly, we analyzed the 4 treatments where we presented predators with 2 bass lets differing in size (small versus large) when comparing predator response between basslet sizes (lionfish: n = 13, graysby: n = 12). If a predator did not display any predatory behavior during any of the 4 treatments described in the treatment groupings above, then the individual was dropped from that respective group prior to analysis (resulting in the final sample sizes reported above).

BCO-DMO Processing Notes:

- reformatted column names to comply with BCO-DMO standards
- reformatted dates 
- nd used to fill blank cells

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?