The Impact of Invasive Lionfish on the Feeding Performance of Endemic Spotted Scorpionfish

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Spring 2018 The mpI act of Invasive Lionfish on the Feeding Performance of Endemic Spotted Scorpionfish Nathaniel Zbasnik Western Kentucky University, [email protected]

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THE IMPACT OF INVASIVE LIONFISH ON THE FEEDING PERFORMANCE OF ENDEMIC SPOTTED SCORPIONFISH

A Thesis Presented to The Faculty of the Department of Biology Western Kentucky University Bowling Green, Kentucky

In Partial Fulfillment Of the Requirements for the Degree Master of Science

By Nathaniel Zbasnik

May 2018

I dedicate this thesis to my wife and life-long partner. Your support

and encouragement has led me to this point. Thank you so much.

iii

ACKNOWLEDGEMENTS

I would like to initially thank Dr. Steve Huskey for advising me throughout my years at WKU and for his tremendous help in making this study possible. Without his foresight and steady hands, I would not have been able to conduct this unique type of work. I would also like to thank Dr. Michael Smith and Dr. Phil Lienesch, who both provided invaluable insight on how to improve the overall quality of my study and thesis.

Thank you to Jessica Dunnegan, Melanie Redden, and all of the biology office staff for helping me adjust to and work through my Master’s degree. The Biograds, you have all been a wonderful support group for me through these past two years, I cannot think of my graduate career without thinking of you all.

Lastly, I would like to thank the Biodiversity Center for supporting me through a teaching assistantship over the last two years and the Office of Graduate Studies and

Research at WKU for providing me with multiple grants in support of my project. I would also like to thank the Institutional Animal Care and Use Committee for approving the procedures used throughout this study.

CONTENTS

Introduction ...... 1

Design of the Study ...... 11

Results ...... 16

Discussion ...... 17

Literature Cited ...... 24

v LIST OF TABLES

Table 1. Description of measured kinematics ...... 34

Table 2. 2-way ANOVA of peak sub-ambient pressure based on body size and treatment

...... 35

Table 3. MANOVA of all measured variables against treatments ...... 36

Table 4. MANOVA of all measured variables against individuals ...... 37

Table 5. Mean: excursion distances of kinematics, time to maximal excursion distance and sub-ambient pressure of spotted scorpionfish based on treatments ...... 38

LIST OF FIGURES

Figure 1. Cannula insertion ...... 39

Figure 2. Pressure trace example ...... 40

Figure 3. Illustration of an example of the measurements of the feeding kinematics ...... 41

Figure 4. Linear model of peak sub-ambient pressure versus body size ...... 42

Figure 5. Linear model of max gape excursion distance versus body size ...... 43

Figure 6. Linear model of max hyoid excursion distance versus body size ...... 44

Figure 7. Linear model of max cranial elevation versus body size ...... 45

Figure 8. Linear model of peak sub-ambient pressure versus max cranial elevation ...... 46

Figure 9. Linear model of peak sub-ambient pressure versus max gape excursion

distance ...... 47

Figure 10. Linear model of peak sub-ambient pressure versus max hyoid excursion

distance ...... 48

Figure 11. Linear model of time to max gape versus gape excursion distance ...... 49

Figure 12. Linear model of time to max hyoid versus hyoid excursion distance ...... 50

Figure 13. Linear model of time to max cranial elevation versus angle of cranial

elevation ...... 51

Figure 14. Linear model of peak sub-ambient pressure versus time to max gape height .52

Figure 15. Linear model of peak sub-ambient pressure versus time to max hyoid

depression ...... 53

Figure 16. Linear model of peak sub-ambient pressure versus time to max cranial

elevation ...... 54

vii

Figure 17. Boxplot of peak sub-ambient pressure between individuals and treatment ....55

Figure 18. Boxplot of peak sub-ambient pressure between treatments ...... 56

viii

THE IMPACT OF INVASIVE LIONFISH ON THE FEEDING PERFORMANCE OF ENDEMIC SPOTTED SCORPIONFISH

Nathaniel Zbasnik May 2018 56 Pages

Directed by: Dr. Steve Huskey, Dr. Michael Smith, and Dr. Phil Lienesch

Department of Biology Western Kentucky University

Invasive species, such as the red lionfish, Pterois volitans, are damaging many ecosystems around the world by out-competing native species. However, little work has been done to determine if P. volitans have a direct influence on the feeding performance of native species with which they compete. This study examines the feeding performance in terms of suction pressure, kinematic timing, and excursion distances of spotted scorpionfish, Scorpaena plumieri. Through multiple trials it was examined how S. plumieri modulate their kinematic behavior in response to P. volitans and a conspecific.

The creation of a smaller buccal cavity and a decrease in time of buccal expansion may allow individuals to create greater sub-ambient pressures to increase their prey-capture success. High-speed cinematography and pressure transducers were used to determine if

S. plumieri modulate feeding performance in the presence of either P. volitans or a conspecific. The results of the study suggest that S. plumieri do not create larger sub- ambient pressures or modulate their feeding kinematics in the presence of P. volitans or a conspecific.

ix INTRODUCTION

Ecosystem resources are necessary for organismal survival, with the distribution of resources being maintained by biotic interactions, like competition. Intra- and interspecific competition drives the limitation of resources that can lead to changes in organisms such as: feeding kinematics (Pfeiffenberger and Motta, 2010), growth rates

(Persson and Greenberg, 1990), and territoriality. The previously mentioned pressures on populations can also lead to speciation events (Schluter and McPhail, 1992). Resource limitation within habitats drive behavioral changes that force species to optimize their foraging success (Dill and Fraser, 1984); nevertheless, individuals may not be able to leave these areas of greater competition due to some sort of barrier, such as a mountain range (Goldberg and Lande, 2007). With increasing intraspecific competition, individuals have the potential to become more aggressive when presented with limited food

(Pfeiffenberger and Motta, 2010), and can reduce the niche breadth of the competitors, resulting in a narrowing of available resources (Bolnick et al., 2010). If individuals cannot leave the area where greater competition is occurring, one or more of the local species may extirpate the weaker one(s) and occupy the niche (Hardin, 1960).

These changes in behavior can be connected to the idea of motivation, therefore, it is critical to understand what the word “motivation” means. For the study we will use the definition of motivation from McFarland (1981) that describes motivation as reversible changes in state that affects the behavior of the organism. Organisms, like fish, have the ability to perceive changes to their environment and react to those changes by altering their behavior(s). For example, if the number of competitors becomes too large and the resource gains of each individual drastically decreases, bluegill, Lepomis

1 macrochirus, (Mittelbach, 1981) and coho salmon, Oncorhynchus kisutch, (Dill and

Fraser, 1984) have been shown to move to new areas to optimize their foraging.

Additionally, fish like L. macrochirus have the ability to perceive densities of competitors and change their feeding behavior to maximize resource gains

(Pfeiffenberger and Motta, 2010). A key part of motivation is that as the stimulus changes, the behavior of the organism(s) is also able to shift. By altering the number of competitors within an area, one would be altering the stimulus, thus changing the behavior of the competitors. Additionally, by changing the type of competitors within an area, organisms may experience more competition. Greater competition is typically experienced between two species that are phylogenetically related, as they will often overlap more in feeding habits, niche, and prey choice when compared to non-familial species (Heck and Weinstein, 1989; Pfeiffenberger and Motta, 2010; Persson and

Greenberg, 1990; Schluter and McPhail, 1992). Competition is further compounded when local predators compete with non-native predators for resources.

Invasive species introductions can cause harm to the environment, humans, animals, or the overall health of the ecosystem (Beck et al., 2008). For a species to be elevated to invasive status it must pass through varying filters. The species must first go through a geographic barrier and move into a non-native area, which can happen through different means. Species moved by any human involvement are considered introduced species (Richardson et al., 2000). Species that are not introduced by humans are moved by natural means, such as flooding, which could open up access to previously restricted areas (Gutierrez and Ponti, 2014). All non-native species are then considered alien species to the new habitat (Richardson et al., 2000). Once the species has been moved,

2 they must then acclimate to the local environmental conditions (both biotic and abiotic barriers). The alien species must then go through a reproductive barrier in the invasive habitat. Once the alien species have successfully reproduced, measured over multiple generations, they are then considered naturalized (Richardson et al., 2000). The naturalized aliens must then be able to disperse throughout the environment. If the species are able to overcome local and environmental dispersal barriers, the species are then considered invasive (Richardson et al., 2000). However, it is important to note that the definition of what the United States Government considers an invasive species is based on if the non-native species causes, or is likely to cause, harm to the health of: humans, the environment, animals, or plants (Executive Order No. 13,112, 1999).

Regardless, if a species does become invasive, it is very difficult to remove them from the environment (Thresher and Kuris, 2004). Fortunately, only small portions of species that are moved to new ecosystems eventually become invasive (Mack et al., 2000).

Those species that do become invasive have numerous advantages that native species lack when competing with local fauna. Some of these advantages include a reduced likelihood of being infected from local pathogens and diseases (Mitchell and

Power, 2003), parasitized by native organisms (Torchin et al., 2003), or subjected to predation (Colautti et al., 2004). These advantages are magnified if the invasive species is particularly aggressive, especially when food is clustered, as competition would increase

(Tanner et al., 2011). This greater competition can lead organisms to modulate some aspect of their behavior to improve their feeding success (Nyberg, 1971; Norton and

Brainerd, 1993; Nemeth, 1997). For fish, this change often takes place within the feeding method (Norton, 1991).

When fish feed, they go through a striking pattern of opening and closing the buccal cavity during a feeding attempt, which is facilitated by the rapid expansion of the cranial skeleton. The expansion of the cranial skeleton enlarges the buccal cavity, creating a sub-ambient pressure required for suction feeding. The pressure inside the buccal cavity is derived from the physical length of the feeding kinematics (excursion distances) and expansion rates of the musculoskeletal system of the cranium (Van

Leeuwen and Muller, 1983; Day et al., 2005; Higham et al., 2006b). The separation between the lower jaw (dentary) and the upper jaw (premaxilla) draws in the prey item and surrounding fluid (Carroll and Wainwright, 2009). The speed with which the prey is captured is dependent upon the kinematic expansion and resultant negative pressure within the buccal cavity.

Many internal and external factors impact the feeding kinematics that influence the pressure generation within the buccal cavity of the fish. Some of these factors include gape size, predator-prey standard length ratio, and type of prey (Wainwright et al., 2001;

Day et al., 2005; Wainwright et al., 2007). Having larger pressures and modulating feeding kinematics based on the prey type will increase the feeding success of fish

(Lauder, 1983; Lauder and Clark, 1984; Nemeth, 1997). Small gape sizes will generate greater flow velocity, focused in a narrow area in front of the mouth, to rapidly draw in water (Carroll et al., 2004; Higham, 2011; Lauder, 1980b; Wainwright and Richard,

1995). Fish may increase their excursion distances to guarantee the prey will be captured.

On the other hand, there is a trade-off between large kinematic excursion distances and internal pressure. Larger gapes allow individuals to capture larger prey at the expense of lower pressures, as these larger gapes require a longer expansion time (Muller et al.,

1982; Carroll et al., 2004). As the magnitude of pressure decreases, the individual will need to include a ram component to successfully capture the prey (Van Leeuwen and

Muller, 1983).

During aquatic feeding, water is drawn into the buccal cavity and is able to escape through the opercula instead of being ingested (Lauder, 1980b; Lauder, 1983; Van

Wassenbergh and Aerts, 2009). The pressure inside the buccal cavity must be lower compared to the surrounding ambient pressure to draw water and prey inward (Lauder,

1980a,b). While the creation of sub-ambient pressure is tied to the feeding kinematics of the individual, the striking speed and excursion distances also determine the velocity and quantity of fluid flow during a feeding event (Day et al., 2005; Higham et al., 2006b).

Capture success and feeding performance depend on the creation of sub-ambient pressure within the buccal cavity and, subsequently, the volume of water entering the buccal cavity (Higham et al., 2006a; Carroll and Wainwright, 2009).

To increase the capture success rate, some fish are able to modulate their feeding kinematics to capture a variety of prey (Nyberg, 1971; Norton and Brainerd, 1993;

Nemeth, 1997; Huskey, 2003). Modulation in fish is the ability to modify both kinematic and pressure outputs by adjusting their feeding performance (Sass and Motta, 2002), which can differ between prey-capturing events (Nyberg, 1971). Fish exhibit two primary feeding strategies, ram and suction, where the ability of a predator to switch between these strategies may confer a competitive advantage in areas of greater competition

(Nyberg, 1971; Day et al., 2005).

All fish fall between true suction feeding and true ram feeding, using some combination of both to feed (Nyberg, 1971; Norton and Brainerd, 1993; Wainwright et

5 al., 2007). Ram feeders produce large gapes and greater attack velocities to capture prey

(Lauder and Liem, 1981), resulting in little to no generation of negative pressure

(Higham et al., 2006a). The larger buccal cavity envelops a larger volume of water, but at a slower velocity (Higham et al., 2006a; Carroll and Wainwright, 2009). Conversely, suction feeders are able to create large sub-ambient pressures (Norton and Brainerd,

1993; Day et al., 2005; Higham et al., 2006a), and must create a pressure gradient large enough to overcome prey escape maneuvers (Muller et al., 1982; Carroll et al., 2004).

Suction feeders possess smaller gape sizes, which results in drawing a smaller volume of water into the buccal cavity but at a greater velocity (Higham et al., 2006a; Carroll and

Wainwright, 2009). The dentary bone needs to be depressed and the head elevated in order to expand the buccal cavity to generate pressure (Grubich and Wainwright, 1997;

Carroll and Wainwright, 2009). When suction feeding occurs, the creation of the largest pressure is typically formed directly in front of the mouth and is increased by protruding the jaw. The jaw protrusion helps the predator get physically close to their prey and increases the suction pressure by creating a more circular opening (Higham, 2011).

Suction pressure is most effective when the prey is close to the mouth of the predator, as pressure weakens further from the origin of the expanding buccal cavity.

To gain an advantage over prey, fish are able to orient themselves within the habitat. This orientation helps by allowing the individual to adjust the required velocity that is needed during a feeding strike. The position of the predator in reference to the prey and the type of prey both influence the predator’s approach and attack velocity (Nyberg,

1971; Norton and Brainerd, 1993; Huskey, 2003). Prey located in the benthos forces predators to slow their approach and get closer to the prey (Nyberg, 1971), resulting in a

6 greater opportunity to adjust their feeding kinematics and increases capture success via suction (Nemeth, 1997). Because the predator decreases its approach velocity and is closer to its prey, this allows for rapid cranial expansion producing stronger suction pressures (Svanback et al., 2002; Higham, 2011). Small fish, contrarily, are more elusive compared to benthic bound individuals (Wainwright and Lauder, 1986; Norton, 1991;

Huskey, 2003), requiring some predators to approach at faster speeds to overtake any evasive maneuvers executed by the prey (Norton, 1991; Tran et al., 2010). Predators also have to adjust their striking position and increase their velocities to ensure a successful prey-capture (Norton, 1991; Tran et al., 2010). When predators give chase to prey they often increase their approach and attack velocities and employ wider gapes to guarantee a successful capture, but at the cost of reduced sub-ambient pressures (Norton and

Brainerd, 1993; Nemeth, 1997; Sass and Motta, 2002; Day et al., 2005).

Scorpaeniformes are bony, ray-finned, venomous fishes that capture prey mainly by suction feeding utilizing ambush tactics (Michael, 1998). The species within this order possess a unique bone extending from the third infraorbital, across the cheek, connecting to the preoperculum called the suborbital stay (Paxton and Eschmeyer, 1998). Spotted scorpionfish (Scorpaena plumieri) and the red lionfish (Pterois volitans) are both marine fish nested within this order and are shallow water carnivores that feed on both fish and crustacean species.

The native Atlantic S. plumieri is a species that inhabits coral reefs and seagrass meadows from Rhode Island to Brazil, residing on the benthos (Heck and Weinstein,

1989; Eschmeyer and Buddo, 2015). S. plumieri mimic the rocky properties of coral reefs, which provide cover from predators and increases their opportunities for successful

7 ambush attacks. The more sedentary lifestyle of S. plumieri influences their feeding success; being motionless allows for the formation of a reduced bow wave during feeding

(Nyberg, 1971; Lauder and Clark, 1984), which maximizes the production of sub- ambient pressure (Van Leeuwen, 1984; Higham et al., 2005).

Anthropogenic factors and natural processes also influence the survival of S. plumieri populations. For example, tourism significantly decreases the abundance of piscivorous fish on coral reefs, such as S. plumieri and other reef predators (Jarri et al.,

2008). Predators, including dolphins and sharks, have a greater chance of consuming S. plumieri when they are caught away from the reef structure where they are no longer cryptic. Increases in local competitors have also been shown to negatively influence the feeding success of multiple marine species (Pfeiffenberger and Motta, 2010; Bolnick et al., 2010). When an invasive species colonizes a region, it can influence multiple native species because habitat space is limited and competition would increase based on the densities of competitors.

P. volitans originate from the Indo-Pacific inhabiting coral reefs and manmade structures. Introduced to the Atlantic Ocean in 1985, P. volitans have caused major damage to the local ecosystems and fisheries, with an invasive area ranging from the

Atlantic Coast of the U.S., Bahamas, and South America, to the Gulf of Mexico (López-

Gómez et al., 2014; Whitfield et al., 2002). P. volitans navigate reefs with impunity because their aposematic coloration drives predators away (Fishelson, 2006). The combination of the coloration and being venomous (Halstead et al., 1955) helped facilitate the surge in their invasion (Colautti et al., 2004). P. volitans have an advantage when they hunt in their new habitat because prey do not recognize them as predators,

8 allowing P. volitans to gravitate closer to prey (Lönnstedt and Mccormick, 2013). The generalist feeding strategy of P. volitans allows the species to consume large quantities of prey, ultimately outcompeting many endemic fishes. P. volitans have numerous documented effects on the habitats they invade, such as reducing: native reef fish populations by a 2.5 greater magnitude than native piscivores (Albins, 2012), species richness (Albins and Hixon, 2008), and native reef fish populations by 79% (within a five-week period) (Muñoz et al., 2011). Their ability to disperse, both as eggs and adults, has allowed P. volitans to become a widespread invasive species.

Ahrenholz and Morris (2010) documented that ocean currents disperse planktonic larvae of P. volitans, and Tamburello and Cote (2015) observed adults are capable of moving up to 1.38 km over a 15-day period in patch-reef habitats. Shulman et al. (1983) found that if juvenile coral reef predators settle before juvenile prey species, the success of settlement for the juvenile prey is significantly reduced. Juvenile P. volitans have a greater effect on invaded coral reef communities compared to their native Pacific coral communities. Their densities in invaded areas is a five-fold magnitude greater, yielding a density of >390 lionfish per hectare (Green and Côté, 2008). Densities of this invasive species are so high in North Carolina that lionfish are in greater abundance than all but one native predator, the scamp grouper (Mycteroperca phenax) (Whitfield et al., 2007).

With such high densities of P. volitans being observed, native predators such as S. plumieri may be impacted more than is currently expected.

S. plumieri was chosen for this study because of their relatedness to P. volitans.

As these two species are phylogenetically related and ecologically similar, we would expect both to overlap more in feeding behaviors, niche, and prey choice when compared

9 to other non-familial species (Heck and Weinstein, 1989; Pfeiffenberger and Motta,

2010; Persson and Greenberg, 1990; Schluter and McPhail, 1992). If S. plumieri do not modulate some aspect of their feeding performance in the presence of P. volitans, there is higher probability of being outcompeted. Limited food within a region will cause competitors to have lower growth rates (Jones, 1986). With food diminishing due to P. volitans, S. plumieri may expend all extra energy feeding on limited prey, causing a reduction in their own growth rate (Heino and Kaitala, 1999). Limited food and higher competition can culminate in the exclusion of S. plumieri from the local environment

(Hardin, 1960), which may have drastic effects on the food web. S. plumieri have been calculated to have an average of five unique interactions with other species in Veracruz,

Mexico, where S. plumieri are either a predator or a prey item (Abarca et al., 2007).

Angelsharks (Squatina squatina) provide an example of a predatory relationship to S. plumieri. These species rely on S. plumieri as food during the winter due to their relative abundance amidst other prey items (Baremore et al., 2008). A healthy population of S. plumieri is also needed to keep local prey populations in check (Rooney et al., 2006).

With the invasive P. volitans becoming a permanent resident within the Atlantic

Ocean, it is critical to understand the future influence they have on the local inhabitants, such as S. plumieri. Future changes to the ecosystem have the potential to shift species ranges and further stresses the need to start conservation efforts earlier, before the impact of the invasive species is irreversible (Munday et al., 2008). The potential impact P. volitans has on the feeding performance of S. plumieri is yet to be documented.

HYPOTHESIS

The focus of this study is to document if P. volitans negatively impact the feeding performance of S. plumieri. The null hypothesis states that S. plumieri will not modulate their feeding performance in the presence of P. volitans. The alternative hypothesis states that S. plumieri will modulate their feeding performance in the presence of P. volitans.

DESIGN OF THE STUDY

All experimental protocols were reviewed and approved by the Institutional Animal

Care and Use Committee (IACUC), designation number 16-05.

Fish Collection and Housing

Six S. plumieri and two P. volitans were purchased from Dynasty Marine, an online retailer from Florida that collected the species from the wild in the Florida Keys.

The individuals were housed in either a 170 or 340-liter aquarium maintained at 20°C.

Salinity was maintained at approximately 35 parts per thousand (ppt). Photoperiods were naturally driven, due to the placement of tanks near windows. Two 170-liter Whisper

Power Filters (Spectrum Brands, Inc.) provided constant filtration of each tank for the duration of the study. Dividers were placed between neighboring tanks so individuals were not able to see other competitors when housed alone.

Feedings were standardized across all individuals. The prey of choice was comet goldfish, Carassius auratus, that were approximately 10% of the standard length of the individual to which it was fed. To maximize feeding strikes during filming, up to 3 prey items, one at a time, were presented to an individual during each trial. All missed feeding

11 attempts were also quantified and used in analyses which could have garnered up to 6 unique feeding attempts per individual within one feeding trial. Trials were conducted only twice a week to avoid satiation, which has been shown to negatively affect feeding performance in largemouth bass (Sass and Motta, 2002). The prey items were tethered and presented to the predator on a dissection probe that was affixed to a long plastic titration tube. This ensured a lateral video recording of the kinematics and allowed for successful feeding attempts of S. plumieri in the presence of P. volitans. Without the tethering probe during feedings, P. volitans consumed 95% of the free-swimming prey during feeding trials. The probed feedings did not cause a significant difference in either pressure (n = 20; t = -0.595; p = 0.56) or kinematics (n = 20; t = 0.847; p = 0.4185), allowing for the use of the probe as the method of feeding throughout the experiment.

Surgical Methods

The fish were submerged in a bath of 1 mg L-1 MS-222 (tricaine methanesulfonate) that acted as a sedative until the individual lost consciousness, depicted by losing its righting response and stopping ventilation. A hole was bored through the rostrum of S. plumieri using a series of hypodermic needles to allow passage of a Millar SPR-407 pressure transducer into the buccal cavity. Ultra-thin walled fly fishing micro tubing measuring 1/16” outer diameter was cut and one end was melted to create a flared end wide enough to rest against the roof of the mouth when mounted within the buccal cavity (Figure 1). The cannula was then secured in place by using a small plastic collar. The fish were then held underwater in their respective tanks with their mouths open with gills manually pumped by compressing the operculum by hand, until the individual could ventilate on its own.

Every S. plumieri was fitted with a Millar SPR-407 pressure transducer by taking them out of the tank, then passing the transducer through the hole in the rostrum and by mounting a rubber sleeve affixed to the transducer over the cannula. Once the transducer was fitted into the cannula, the cannula was filled with water to remove any air and the fish was allowed to recover for thirty minutes before prey was presented. Suction pressure was measured over the course of five months for individuals with their corresponding feeding kinematics. Once filming was completed for the day, the transducers were removed and individuals were returned to their respective tanks.

Filming and Pressure Quantification

Feeding events were recorded at 500 frames per second using a Redlake high- speed digital video camera (Redlake). Pressure traces formed by the fish during feeding strikes (Figure 2) were analyzed using the Midas software, version 2.0 (Xcitex, Inc.).

ImageJ, version 1.48 (NIH, USA) and maxTRAQ software, version 2.0 (Innovision

Systems, Inc.) were used to quantify the feeding kinematics of the individuals.

Individuals had to be perpendicular to the camera during feedings in order for the kinematic variables to be accurately measured. A gridded background of 1cm × 1cm squares was installed behind each tank for scale. Two light stands were positioned in front of the tank opposite of the gridded background. Each light was angled towards the fish being filmed at a 45-degree downward angle to reduce any shadows that may obscure the grid. Each light bulb in the stands was rated for 250W.

A Millar SPR-407 pressure transducer (Millar, Inc.) was employed to measure the pressure inside the buccal cavity and was synchronized with the high-speed video camera

13 for each trial. Peak negative pressures were transformed from unitless values generated by the Midas program into millimeters of mercury (mmHg) and ultimately into kilopascals (kPa). When a pressure trace was recorded, the pressure control unit was switched between recording (transducer), to standby and ultimately to 20 mmHg. The pressure controller unit had an internal standard 20mmHg setting that was automatically calibrated. The difference between the peak pressure and standby was measured as peak sub-ambient pressure and from standby to 20 mmHg. Once a standardized difference was measured (standby to 20mmHg) the peak pressure was transformed into millimeters of mercury using the ratio. The resulting pressure was then transformed into kilopascals by converting it from mmHg.

Key kinematic variables of the feeding performance were analyzed (Table 1,

Figure 3) using ImageJ software and are modeled after Huskey (2003). The variables of interest are as follows: maximum gape height (mm), hyoid depression (mm), and cranial elevation (degree). Maximum gape height was measured at the maximum opening of the anterior point of the premaxilla to the most distal point of the dentary bone. Hyoid depression was measured from the middle of the eye to the floor of the buccal. Cranial elevation was measured as an angle between the base of the pectoral fin, the first dorsal spine, and the tip of the premaxilla.

The time at which maximum gape, maximum hyoid depression, and maximum cranial elevation occurred from Time 0 (the time of mouth opening) was measured as timing variables (ms). The gape cycle is the time it takes the fish from Time 0 to successfully capture the prey and close the mouth after a feeding strike. Angles of cranial

14 elevation measured in degrees were measured at Time 0 and at the time of peak extension to generate a relative difference of cranial elevation for a singular feeding strike.

Experimental Treatments

Individual S. plumieri underwent three different experimental treatments to compare modulation of feeding kinematics. S. plumieri were initially isolated (control feedings) from all competitors and will be referred to as the isolated group. S. plumieri were also fed in the presence of a lionfish (interspecific competition) and will be referred to as the lionfish group. Lastly, S. plumieri were fed when only one conspecific

(intraspecific competition) was added to a tank and will be referred to as the scorpionfish group.

Statistical Analysis

To test for significant differences in feeding performance, based on the feeding kinematics and pressure recordings, statistical software RStudio version 1.0.143 (R Core

Team, 2015) was utilized. An analysis of variance (ANOVA; Dowdy and Wearden,

1991) was performed using the stats package in RStudio (R Core Team, 2015) to determine if the treatment or the body size of individuals had an affect on the pressure generated from S. plumieri. Standard length (SL), measured in centimeters, was not used as a covariate as there is no significant correlation between SL and pressure (Figure 4). A multivariate analysis of variance (MANOVA; Tabachnick, 1983) was performed using the package dplyr in RStudio (Wickham, 2017) to determine if there was any significant difference in the feeding kinematics and timing variables between treatments.

RESULTS

A total of 225 feeding events (91 isolated; 73 lionfish; 61 scorpionfish) from six S. plumieri were recorded. To account for pseudoreplication within the dataset, the means for each individual across all variables were calculated. This accounts for six mean values of each variable to compare across all treatments.

Figure 4 suggests that larger individuals have a trend to create greater sub-ambient pressures. However, as body size has no significant influence over either pressure or excursion distances (p = 0.42; p > 0.05), it is not necessary to remove this influence from the dataset (Table 2 and 4). This allowed us to employ statistics that do not consider covariates for analyses.

The two-way ANOVA revealed that buccal pressure did not change significantly

(F = 0.189, p = 0.83) based on whether or not a P. volitans or a conspecific was in a tank

(Table 2). An additional ANOVA discovered that feeding order had no significant influence (F = 0.166; p = 0.683) over the mean peak pressure generated. Order refers to the sequence in which the prey was presented to the predator, with higher ordered prey being presented later in the same feeding trial.

MANOVAs were utilized to parse out if either the treatment or individuals had a significant effect on the feeding kinematics. The variables included were: time to maximum expansion of the gape (ms), time to maximum expansion of the hyoid (ms), time to maximum expansion of the angle of cranial elevation (ms), maximum gape height

(mm), maximum hyoid depression (mm), and angle of cranial elevation (degrees). The

16 tests revealed that all of the measured variables were not different based on either the treatment (Table 3) or individual (Table 4).

The generalized linear model between mean pressure and standard length of S. plumieri suggests there may be a positive trend of larger individuals creating larger pressures (Figure 4). Additionally, larger individuals may have the ability of generating larger mean excursion distances compared to smaller conspecifics (Figures 5-7). These larger excursion distances, however, may be responsible for creating smaller sub-ambient pressures compared to the smaller distances (Figures 5-7). It is important to know that none of these relationships are significant and require more replications to strengthen any observed trend.

DISCUSSION

Feeding

Suction feeding can be divided into key kinematics required to create sub-ambient pressure for prey-capture. The mobility of the jaw allows the predator to expand the buccal cavity to create a larger space to draw in greater volumes of water (Westneat,

2005). The depression of the hyoid causes the dentary to rotate downward, drawing in the surrounding water, and increasing the volume of the buccal cavity (Aerts, 1991). Cranial elevation starts the expansive phase of a feeding strike, and as the cranium moves upwards, it raises both the roof of the mouth and premaxilla of the fish (Westneat, 2005).

According to the data, there is a negative relationship between mean peak pressure and excursion distance of each kinematic (Figures 8-10). This suggests that S. plumieri may

17 be able to generate larger pressures by creating smaller excursion distances. By restricting the excursion distances, the time to expand the buccal cavity also decreases

(Figures 11-13). This observation suggests that the expansion rate may be the same, regardless of the size of the excursion distance, which means that it will take larger S. plumieri more time to expand their buccal cavity compared to smaller conspecifics. It has been well documented that both speed and length of the feeding kinematics contribute in creating sub-ambient pressure (Van Leeuwen and Muller, 1983; Day et al., 2005; Higham et al., 2006b). This study concurs with previous papers suggesting that the speed of expansion (Figures 14-16) facilitates the creation of lower sub-ambient pressure (Day et al., 2005; Higham et al., 2006b). Additionally, this work suggests larger excursion distances create less pressure (Figures 8-10). It is hypothesized that as individuals expand the volume of the buccal cavity to greater extents, it requires the individual(s) to spend more time expanding their mouth, resulting in less generated pressure.

Feeding Order

It is known that satiation negatively impacts the feeding performance of largemouth bass (Micropterus salmoides) (Sass and Motta, 2002) that could also influence the feeding performance of S. plumieri. To minimize the effects of satiation on

S. plumieri, individuals were fed a restricted diet every week. Yet it is also critical to understand if the order of feeding influences the generated pressure as well. Analysis of feeding order demonstrates that the order has no significant influence over the mean peak pressure generated (p = 0.683). Signifying that, on average, the maximum pressure generated on the third successful feeding strike has the same magnitude as that generated

18 on the first. This suggests that S. plumieri performed equally throughout all feeding trials.

Because pressure does not differ based on the feeding order, this implies any change in pressure from S. plumieri must be elicited from stimuli of the surrounding competitors.

Pressure

An ANOVA was initially conducted to test if individual S. plumieri were influencing the pressure data. The test revealed that individual S. plumieri did not significantly differ in their ability to generate pressure (p= 0.81). The non-significance of this analysis allows the utilization of all data, as no individual significantly differs in the potential to generate pressure. A second ANOVA determined the experimental treatments do not statistically influence the mean maximum pressure (Table 2, p = 0.83). It is interesting to note that the mean pressure generated by S. plumieri is lowest when they are isolated (10.023 kPa), increases in the presence of a conspecific (10.341 kPa) and further increases when P. volitans is introduced (11.21 kPa; Table 5). The statistical analysis leads us to fail to reject the null hypothesis, stating that S. plumieri are not creating significantly greater sub-ambient pressures in the presence of P. volitans.

Considering the overall trend of increasing pressure within the presence of a competitor, it is hypothesized that without a competitor there is less need to generate greater sub- ambient pressures to capture prey. When an invasive species is added, S. plumieri may generate more pressure to successfully capture prey in order to outcompete the invasive competitor. As the invasive species may be an unrecognized organism by S. plumieri, it may elicit a stronger feeding effort from S. plumieri to guarantee a successful prey- capture. It is also plausible that S. plumieri learned to generate stronger pressures in the

19 presence of P. volitans to capture a greater amount of prey. However, this is all speculation and requires more data for statistical support.

It is also important to determine the range of pressure S. plumieri produced in each treatment. Without a competitor the pressure range generated by S. plumieri had the potential to be greater compared to when individuals were housed with a competitor

(Figure 17). This greater range may have been due to the individual adjusting to their new surroundings, as the isolated data was always the first group to be measured. However, this is unlikely as isolated individuals still exhibited greater pressure ranges after a month elapsed, which provided ample time for individuals to acclimate to their tanks. The addition of a competitor may require S. plumieri to create narrower ranges of generated pressures to maximize their feeding success. The changes in feeding effort follows the previous work of Pfeiffenberger and Motta (2010) that found by increasing intraspecific competition; L. macrochirus changed their feeding performance to capture limited prey.

However, with pressure not statistically changing between treatments (Figure 18), S. plumieri are not modulating their kinematics differently in the presence of P. volitans or a conspecific.

Kinematics

It is important to understand if individual S. plumieri are influencing the overall data set by significantly changing their kinematics differently from each other. The

MANOVA showed that individuals did not significantly influence any kinematic variable

(Table 4, p > 0.05). This allowed the utilization of all measured individuals to test if there was a significant interaction between experimental treatments and the dependent

20 variables. The results of a second MANOVA suggest that no kinematic variable is significantly changing based on the treatment (Table 3, p > 0.05). However, as there is a slight change in mean sub-ambient pressure between the treatments, this suggests that the kinematics may show a similar trend. Although these changes are not statistically different, they may still have ecological relevance. Table 5 suggests that the difference in pressure between the isolated and lionfish groups relied on the ability of S. plumieri to expand their buccal cavity quicker in the presence of P. volitans. Again, this is speculation and would need to be validated with a more robust data set.

Feeding Performance

S. plumieri have the potential to generate greater pressure ranges when they are isolated from other competitors. This may be because isolated individuals do not have to compete, which would reduce the need for the creation of consistent pressures. This does not rule out weekly variation in energy expenditure, as some fish may have expended more energy before filming. It has been shown that brook trout (Salvelinus fontinalis) expend more energy during bouts of intermittent swimming compared to unidirectional movement (Krohn and Boisclair, 1994). For S. plumieri, who are ambush predators and experience random bouts of swimming, they may utilize more energy some weeks compared to others. The weekly variation of energy utilization could possibly influence the observed generated pressure.

This study suggests that S. plumieri are not changing their feeding performance in the presence of a conspecific or invasive competitor. One aspect of feeding not discussed throughout this study is the approach behavior of S. plumieri. It is possible that these

21 organisms are changing their approach behavior due to competitors. However, it was not possible to examine this within the study due to distances of tethered prey varying from

S. plumieri. If S. plumieri could have outcompeted lionfish while feeding on free- swimming prey, then approach behavior could have been quantified. S. plumieri not modulating their feeding performance may have the potential to decrease their success of prey-capture within the presence of this invasive competitor. If another invasive species were introduced into the habitat, we would also anticipate S. plumieri to not modulate their feeding performance.

General Conclusions

Population sizes of P. volitans have exponentially increased in recent years

(Whitfield et al., 2007) because of a lack of native predators and an almost perfect combination of substrate, such as seagrass meadows, and prey. As time progresses, it is possible that groupers or dolphins will be able to incorporate the invasive species as a main source of food. Without any natural predators or effective management strategies, however, population growth of P. volitans will proceed unchecked.

Over time, species that occupy the same niche as P. volitans may be excluded from the area in response to the greater competition for resources (Hardin, 1960). Even though P. volitans can reside in the water column, they also move about freely and are in close proximity to rocky outcroppings, coral reefs, and man-made structures (Green and

Côté, 2008; Whitfield et al., 2007) where S. plumieri reside. Because of these close distances and large densities of P. volitans, there is a chance that S. plumieri will compete more with P. volitans instead of their conspecifics. This suggests that P. volitans will

22 create a greater ecological pressure on S. plumieri to perform, resulting in a more stressful environment for current and future generations of S. plumieri.

This study suggests that by not modulating their feeding performance in response to this invasive species, S. plumieri may be extirpated from their native habitat by P. volitans as they are the weaker competitor. This may cause S. plumieri to forage in other areas similar to what L. macrochirus and O. kisutch do in the presence of high densities of competitors (Mittelbach, 1981; Dill and Fraser, 1984). If S. plumieri are displaced due to this competitor, they have a higher potential for being predated upon by native piscivores in areas where they are no longer cryptic. As food may become scarce in the future as the population densities of P. volitans increases (Morris and Whitfield, 2009), S. plumieri may experience a shift towards reduced fecundity, body (Heino and Kaitala,

1999), and population sizes (Persson and Greenberg, 1990). This stresses the need for sound management plans in the future to restrict the spread of P. volitans.

Currently, main management plans focus on controlling the spread of invasive species by restricting the pathways to new unaffected areas (Carlton and Ruiz, 2005), which may not be enough to contain P. volitans from spreading over time. This is why local restaurants in Florida are placing P. volitans on their menus to try to increase the economic interest and desires of these fish following NOAA’s “Eat Lionfish” campaign

(NOAA, 2011). Any future management plan should be centered on controlling the spread into breeding grounds of native fish, as these areas are the source of new juvenile recruits (Pulliam, 1988). If the populations of this invasive species are not reduced, drastic changes to the populations of S. plumieri may occur over time.

LITERATURE CITED

Abarca-Arenas, L., Franco-Lopez, J., Peterson, M., Brown-Peterson, N., and

Valero-Pacheco, E. (2007). Sociometric analysis of the role of penaeids in the

continental shelf food web off Veracruz, Mexico based on by-catch. Fisheries

Research. 87, 46-57.

Aerts, P. (1991). Hyoid morphology and movements relative to abducting forces during

feeding in Astatotilapia elegans (Teleostei: Cichlidae). The Journal of

Morphology. 208, 323-345.

Ahrenholz, D., and Morris, J. (2010). Larval duration of the lionfish, Pterois volitans

along the Bahamian archipelago. Environmental Biology of Fishes. 88, 305-309.

Albins, M. (2012). Effects of invasive Pacific red lionfish, Pterois volitans, versus a

native predator on Bahamian coral-reef fish communities. Biological Invasions.

15, 29-43.

Albins, M., and Hixon, M. (2008). Invasive Indo-Pacific lionfish, Pterois volitans,

reduce recruitment of Atlantic coral-reef fishes. The Marine Ecology Progress

Series. 367, 233-238.

Baremore, I., Murie, D., and Carlson, J. (2008). Prey selection by the Atlantic angel

shark, Squantina dumeril, in the northeastern Gulf of Mexico. Bulletin of Marine

Science. 82, 297-313.

Beck, K., Zimmerman, K., Schardt, J., Stone, J., Lukens, R., Reichard, S., Randall

J., Cangelosi, A., Cooper, D., and Thompson, J. (2008). Invasive species

defined in a policy context: recommendations from the Federal Invasive Species

Advisory Committee. Invasive Plant Science and Management. 1, 414-421.

Bolnick, D., Ingram, T., Stutz, W., Snowberg, L., Lau, O., and Paull, J. (2010).

Ecological release from interspecific competition leads to decoupled changes in

population and individual niche width. Proceedings of the Royal Society B:

Biological Sciences. 277, 1789-1797.

Carlton, J., and Ruiz, G. (2005). In invasive alien species: a new synthesis. (1st ed.).

Washington D.C: Island Press, 36-58.

Carroll, A., Wainwright, P., Huskey, S., Collar, D., and Turingan, R. (2004).

Morphology predicts suction feeding performance in centrarchid fishes. The

Journal of Experimental Biology. 207, 3873-3881.

Carroll, A., and Wainwright, P. (2009). Energetic limitations on suction feeding

performance in centrarchid fishes. The Journal of Experimental Biology. 212,

3241-3251.

Colautti, R., Ricciardi, A., Grigorovich, I., and Macisaac, H. (2004). Is invasion

success explained by the enemy release hypothesis? Ecology Letters. 7, 721-733.

Day, S., Higham, T., Cheer, A., and Wainwright, P. (2005). Spatial and temporal

patterns of water flow generated by suction-feeding bluegill sunfish Lepomis

macrochirus resolved by particle image velocimetry. The Journal of Experimental

Biology. 208, 2661-2671.

Dowdy, S. and Wearden, S. (1991) Statistics for Research. (2nd ed.) New York, NY:

Wiley-Interscience. 629.

Eschmeyer, W. and Buddo, D. (2015). Scorpaena plumieri. The IUCN Red List of

Threatened Species.

Exec. Order No. 13112, 3 C.F.R. 6183-6186 (1999).

Fishelson, L. (2006). Evolution in action-peacock-feather like supraocular tentacles of

the lionfish, Pterois volitans – the distribution of a new signal. Environmental

Biology of Fishes. 75,343-348.

Goldberg, E., and Lande, R. (2007). Species’ borders and dispersal barriers. The

American Naturalist. 170, 297-304.

Green, S., and Côté, I. (2008). Record densities of Indo-Pacific lionfish on Bahamian

coral reefs. Coral Reefs. 28, 107-107.

Grubich, J., and Wainwright, P. (1997). Motor basis of suction feeding performance in

largemouth bass. The Journal of Experimental Biology. 277, 1-13.

Gutierrez, A., and Ponti, L. (2014). Invasive species and global climate change.

Wallingford, UK: CABI Publishing, 271-290.

Halstead, B., Chitwood, M., and Modglin, F. (1955). The anatomy of the venom

apparatus of the zebrafish, Pterois volitans (Linnaeus). The Anatomical Record.

122, 317-333.

Heck, K., and Weinstein, M. (1989). Feeding habits of juvenile reef fishes associated

with Panamanian seagrass meadows. Bulletin of Marine Science. 45, 626-636.

Heino, and Kaitala. (1999). Evolution of resource allocation between growth and

reproduction in animals with indeterminate growth. The Journal of Evolutionary

Biology. 12, 423-429.

Higham, T. (2011). Encyclopedia of Fish Physiology: From Genome to Environment.

San Diego, CA: Academic Press, 597-602.

Higham, T., Day, S., and Wainwright, P. (2006a). Multidimensional analysis of suction

feeding performance in fishes: fluid speed, acceleration, strike accuracy and the

ingested volume of water. The Journal of Experimental Biology. 209, 2713-2725.

Higham, T., Day, S., and Wainwright, P. (2006b). The pressures of suction feeding: the

relation between buccal pressure and induced fluid speed in centrarchid fishes.

The Journal of Experimental Biology. 209, 3281-3287.

Huskey, S. (2003). Functional and morphological bases of intraspecific variation in the

feeding ecomorphology of largemouth bass, Micropterus salmoides. Ph.D.

dissertation, Florida Institute of Technology.

Jarri, M., Souza, A., Medeiros, P., Grempel, R., and Rosa, I. (2008). Effects of tourist

visitation and supplementary feeding on fish assemblage composition on a

tropical reef in the Southwestern Atlantic. Neotropical Ichthyology. 6.

Jones, G. (1986). Food availability affects growth in a coral reef fish. Oecologia. 70,

136-139.

Krohn, M. and Boisclair, D. (1994). Use of stereo-video system to estimate the energy

expenditure of free-swimming fish. Canadian Journal of Fisheries and Aquatic

Sciences. 51, 1119-1127.

Lauder, G. (1980a). Evolution of the feeding mechanism in primitive actinopterygian

fishes: a functional anatomical analysis of Polypterus, Lepisosteus, and Amia.

Journal of Morphology. 163, 283-317.

Lauder, G. (1980b). The suction feeding mechanism in sunfishes (Lepomis): and

experimental analysis. The Journal of Experimental Biology. 88, 49-72.

Lauder, G. (1983). Prey capture hydrodynamics in fishes: experimental tests of two

models. The Journal of Experimental Biology. 104, 1-13.

Lauder, G., and Clark, B. (1984). Water flow patterns during prey-capture by teleost

fishes. The Journal of Experimental Biology. 113, 143-150.

Lauder, G., and Liem, K. (1981). Prey capture by Luciocephalus pulcher: implications

for models of jaw protrusion in teleost fish. Environmental Biology of Fishes. 6,

257-268.

Lönnstedt, O., and Mccormick, M. (2013). Ultimate predators: lionfish have evolved to

circumvent prey risk assessment abilities. PLoS ONE.

López-Gómez, M., Aguilar-Perera, A. and Perera-Chan, L. (2014) Mayan diver-

fishers as citizen scientists: detection and monitoring of the invasive red lionfish

in the Parque Nacional Arrecife Alacranes, southern Gulf of Mexico. Biological

Invasions. 16, 1351.

Mack, R., Simberloff, D., Lonsdale, W., Evans, H., Clout, M., and Bazzaz, F. (2000).

Biotic invasions: causes, epidemiology, global consequences, and control.

Ecological Applications. 10, 689-710.

McFarland, D. (1981). The Oxford Companion to Animal Behaviour. Oxford, UK:

Oxford University Press.

Michael, S. (1998). Reef fishes: a guide to their identification, behavior and captive care.

Portland, OR: Microcosm. 453 - 489.

Mitchell, C., and Power, A. (2003). Release of invasive plants from fungal and viral

pathogens. Nature. 421, 625-627.

Morris, J. and Whitfield, P. (2009). Biology, ecology, control and management of the

invasive Indo-Pacific lionfish: an updated integrated assessment. NOAA

Technical Memorandum NOS NCCOS. 99, 57.

Muller, M., Osse, J., and Verhagen, J. (1982). A quantitative hydrodynamical model of

suction feeding in fish. The Journal of Theoretical Biology. 95, 49-75.

Munday, P., Jones, G., Pratchett, M., and Williams, A. (2008). Climate change and

the future for coral reef fishes. Fish and Fisheries. 9, 261-285.

Muñoz, R., Currin, C., and Whitfield, P. (2011). Diet of invasive lionfish on hard

bottom reefs of the southeast USA: insights from stomach contents and stable

isotopes. The Marine Ecology Progress Series. 432, 181-193.

Nemeth, D. (1997). Modulation of attack behavior and its effects on feeding performance

in a trophic generalist fish, Hexagrammos decagrammus. The Journal of

Experimental Biology. 200, 2155-2164.

NOAA. (2011) Filleting the Lion. NOAA Weekly News, National Oceanic and

Atmospheric Administration.

Norton, S. (1991). Capture success and diet of cottid fishes: the role of predator

morphology and attack kinematics. Ecology. 72, 1807-1819.

Norton, S., and Brainerd, E. (1993). Convergence in the feeding mechanics of

ecomorphologically similar species in the Centrarchidae and Cichlidae. The

Journal of Experimental Biology. 176, 11-29.

Nyberg, D. (1971). Prey capture in the largemouth bass. The American Midland

Naturalist. 86, 129-142.

Paxton, J., and Eschmeyer, W. (1998). Encyclopedia of fishes. San Diego, CA:

Academic Press. 175.

Persson, L., and Greenberg, L. (1990). Interspecific and intraspecific size class

competition affecting resource use and growth of perch, Perca fluviatilis. Oikos.

59, 97-106.

Pfeiffenberger, J., and Motta, P. (2011). The effects of intraspecific competition on the

prey capture behavior and kinematics of the bluegill sunfish, Lepomis

macrochirus. Environmental Biology of Fishes. 93, 13-21.

Pulliam, H. (1988). Sources, sinks, and population regulation. The American Naturalist.

132, 652-661.

R Core Team. (2015). R: A language and environment for statistical computing. R

Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-

project.org/.

Richardson, D., Pysek, P., Rejmanek, M., Barbour, M., Panetta, F., and West, C.

(2000). Naturalization and invasion of alien plants: concepts and definitions.

Diversity and Distributions. 6, 93-107.

Rooney, N., Mccann, K., Gellner, G., and Moore, J. (2006). Structural asymmetry and

the stability of diverse food webs. Nature. 442, 265-269.

Sass, G. and Motta, P. (2002). The effects of satiation on strike mode and prey-capture

kinematics in the largemouth bass, Micropterus salmoides. Environmental

Biology of Fishes. 65, 441–454.

Schluter, D., and Mcphail, J. (1992). Ecological character displacement and speciation

in sticklebacks. The American Naturalist. 140, 85-108.

Shulman, M., Ogden, J., Ebersole, J., Mcfarland, W., Miller, S., and Wolf, N. (1983).

Priority effects in the recruitment of juvenile coral reef fishes. Ecology. 64, 1508-

1513.

Svanbäck, R., Wainwright, P., and Ferry‐Graham, L. (2002). Linking cranial

kinematics, buccal pressure, and suction feeding performance in largemouth bass.

Physiological and Biochemical Zoology. 75, 532-543.

Tabachnick, B., and Fidell, L. (1983). Using multivariate statistics. New York, NY:

Harper & Row.

Tamburello, N., and Cote, I. (2015). Movement ecology of Indo-Pacific lionfish on

Caribbean coral reefs and its implications for invasion dynamics. Biological

Invasions. 17, 1639-1653.

Tanner, C., Salali, G., and Jackson, A. (2011). Feeding and non-feeding aggression can

be induced in invasive shore crabs by altering food distribution. Behavioral

Ecology and Sociobiology. 65, 249-256.

Thresher, R., and Kuris, A. (2004). Options for managing invasive marine species.

Biological Invasions. 6, 295-300.

Torchin, M. E., Lafferty, K. D., Dobson, A. P., Mckenzie, V. J., and Kuris, A. M.

(2003). Introduced species and their missing parasites. Nature. 421, 628-630.

Tran, H. Q., Mehta, R. S., and Wainwright, P. C. (2010). Effects of ram speed on

prey-capture kinematics of juvenile Indo-Pacific tarpon, Megalops cyprinoides.

Zoology. 113, 75-84.

Van Leeuwen, J., and Muller, M. (1983). The recordings and interpretation of pressure

in prey sucking fish. Netherlands Journal of Zoology. 33, 425-475.

Van Wassenbergh, S., and Aerts, O. (2009). Aquatic suction feeding dynamics:

insights from computational modeling. The Journal of the Royal Society Interface.

6, 149-158.

Wainwright, P. C. and Lauder, G. V. (1986). Feeding biology of sunfishes: patterns of

variation in the feeding mechanism. Zoological Journal of the Linnaean Society.

88, 217-228.

Wainwright, P., Ferry-Graham, L., Waltzek, T., Carroll, A., Hulsey, C., and

Grubich, J. (2001). Evaluating the use of ram and suction during prey-capture by

cichlid fishes. The Journal of Experimental Biology. 204, 3039-3051.

Wainwright, P., and Richard, B. (1995). Scaling the feeding mechanism of the

largemouth bass (Micropterus salmoides): motor pattern. The Journal of

Experimental Biology. 198, 1161-1171.

Wainwright, P., Carroll, A., Collar, D., Day, S., Higham, T., and Holzman, R.

(2007). Suction feeding mechanics, performance, and diversity in fishes.

Integrative and Comparative Biology. 47, 96-106.

Westneat, M. (2005). Skull biomechanics and suction feeding in fishes. Fish Physiology.

23, 29–75.

Whitfield, P., Gardner, T., Vives, S., Gilligan, M., Ray, W., Ray, G., and Hare, J.

(2002). Biological invasion of the Indo-Pacific lionfish Pterois volitans along the

Atlantic coast of North America. The Marine Ecology Progress Series. 235, 289-

297.

Whitfield, P., Hare, J., David, A., Harter, S., Muñoz, R., and Addison, C. (2007).

Abundance estimates of the Indo-Pacific lionfish, Pterois volitans/miles, complex

in the western North Atlantic. Biological Invasions. 9, 53-64.

Wickham, H. (2017). R: package, dplyr: Software for multivariate analysis of variance.

Table 1. A description of key feeding kinematics measured using ImageJ for buccal pressure and a description of how the measurements were taken.

Feeding Kinematic Description of Measurement Measurement Collection The distance between the Measured during peak Maximum Gape Height premaxilla and the dentary at expansion maximum extension The distance from the center Measured as the of the eye to the anterior tip of difference between Time Hyoid Depression the hyoid bar as the hyoid was 0 and maximum fully depressed expansion Cranial elevation at time zero Measured as the reflects an angle from the base difference between Time Cranial Elevation of the pectoral fin, to the first 0 and maximum spine of the dorsal fin, to the expansion tip of the premaxilla

Table 2. 2-way ANOVA table for the dependent variable of peak sub-ambient pressure (kPa) based on body size and treatment. Alpha value of 0.05. df SS MS F P-value Body Size 1 8.384 8.384 0.6982 0.4197 Treatment 2 4.536 2.268 0.1889 0.8303 Body Size*Treatment 2 5.951 2.976 0.2478 0.7844 Residuals 12 144.1 12.01

Table 3. MANOVA table of all data with the dependent variables of time to max extension of gape (ms), time to max extension of hyoid (ms), time to max extension of cranium (ms), maximum gape (mm), hyoid depression (mm), cranial elevation (degree). Alpha value of 0.05.

df SS MS F P-value Treatment Time to Max 2 1.335 0.6675 0.356 0.706 Extension of Gape Time to Max 2 1.742 0.8708 0.6211 0.551 Extension of Hyoid Time to Max Extension of 2 3.991 1.996 0.5765 0.574 Cranium Maximum Gape 2 1.089 0.5444 1.3735 0.283 Height Maximum Hyoid 2 0.034 0.0171 0.1687 0.846 Depression Angle Elevation 2 5.984 2.992 0.0538 0.948 Residuals Time to Max 15 28.13 1.875 Extension of Gape Time to Max 15 21.03 1.402 Extension of Hyoid Time to Max Extension of 15 51.93 3.462 Cranium Maximum Gape 15 5.945 0.3964 Height Maximum Hyoid 15 1.519 0.1012 Depression Angle Elevation 15 833.5 55.57

Table 4. MANOVA table of all data with the dependent variables of time to max extension of gape (ms), time to max extension of hyoid (ms), time to max extension of cranium (ms), maximum gape (mm), hyoid depression (mm), cranial elevation (degree) compared against all individuals. Alpha value of 0.05.

df SS MS F P-value Individual Time to Max 5 16.39 3.279 3.012 0.055 Extension of Gape Time to Max 5 10.09 2.019 1.911 0.166 Extension of Hyoid Time to Max Extension of 5 22.81 4.562 1.653 0.22 Cranium Maximum Gape 5 3.86 0.772 2.919 0.06 Height Maximum Hyoid 5 0.636 0.1272 1.664 0.217 Depression Angle Elevation 5 45.38 9.076 0.137 0.98 Residuals Time to Max 12 13.06 1.089 Extension of Gape Time to Max 12 12.68 1.057 Extension of Hyoid Time to Max Extension of 12 33.11 2.759 Cranium Maximum Gape 12 3.174 0.2645 Height Maximum Hyoid 12 0.917 0.0764 Depression Angle Elevation 12 794.133 66.18

Table 5. The mean time it took individuals to reach maximal extension of all kinematics, the mean excursion distance of the kinematics and the mean pressures generated, of spotted scorpionfish based on the treatment.

Mean Hyoid Mean time to Mean time to Mean time to Mean Mean Gape Mean Angle Depressed max gape max Hyoid max elevation pressure Treatment Height (cm) (degree) (cm) (ms) (ms) (ms) (kPa) Isolated 2.8383 25.395 1.3509 6.8060 8.1464 8.6844 10.023 Lionfish 3.3437 24.978 1.4431 6.1742 7.4503 8.2742 11.213

Scorpionfish 3.3750 26.355 1.3503 6.6754 8.0667 9.4128 10.341

Figure 1. A plastic cannula with a flanged base was inserted into the buccal cavity of each individual to create an opening for the tip of the Millar pressure catheter to be threaded into the cavity.

Figure 2. A pressure trace created from an individual spotted scorpionfish during a feeding strike. The flat line represents the ambient pressure within the buccal cavity of an individual, with a max negative peak representing the max-generated pressure created from the individual during a feeding strike.

C B

Figure 3. An example of a still image from ImageJ of kinematic excursion distances being measured of a spotted scorpionfish where: A is the measurement of the maximal cranial elevation angle, B is the measurement of a fully depressed hyoid during a feeding strike, and C represents the maximum gape height.

Figure 4. Linear model illustrating the variation of peak sub-ambient pressure between mean peak pressures generated (kPa) from all individuals and their standard length size (cm) during a feeding strike. Each circle represents an individual with their mean resultant pressure against their own body size.

Figure 5. Linear model illustrating the variation of the mean maximum gape height (cm) created in a feeding strike and the individual’s standard length (cm). Each circle represents a mean of all feeding strikes of each individual with their mean resultant kinematic extension against their own body size.

Figure 6. Linear model illustrating the variation of the mean maximum hyoid depression (cm) created in a feeding strike and the individual’s standard length (cm). Each circle represents a mean of all feeding strikes of each individual with their mean resultant kinematic extension against their own body size.

Figure 7. Linear model illustrating the variation of the mean maximum cranial elevation (degree) created in a feeding strike and the individual’s standard length (cm). Each circle represents a mean of all feeding strikes of each individual with their mean resultant kinematic extension against their own body size.

Figure 8. Linear model illustrating the variation in peak sub-ambient pressure (kPa) between mean peak pressures generated (kPa) from all individuals and the mean maximum angle generated by the individual during a feeding strike. Each circle represents a mean of all feeding strikes of each individual with their mean resultant pressure (kPa) and mean angle generated (degree) generated for all feeding events.

Figure 9. Linear model illustrating the variation in peak sub-ambient pressure (kPa) between mean peak pressures generated (kPa) from all individuals and the mean maximum gape height (cm) by the individual during a feeding strike. Each circle represents a mean of all feeding strikes of each individual with their mean resultant pressure (kPa) and mean gape height (cm) generated for all feeding events.

Figure 10. Linear model illustrating the variation in peak sub-ambient pressure (kPa) between mean peak pressures generated (kPa) from all individuals and the mean maximum hyoid depression (cm) generated by the individual during a feeding strike. Each circle represents a mean of all feeding strikes of each individual with their mean resultant pressure (kPa) and mean hyoid depression (cm) generated for all feeding events.

Figure 11. Linear model illustrating the mean time (ms) it took to reach the maximum extension of the gape and the mean length the gape was extended (cm). Each circle represents a mean of all feeding strikes of each individual with their mean resultant kinematic angle and mean time to peak extension.

Figure 12. Linear model illustrating the mean time (ms) it took to reach the maximum extension of the hyoid and the mean length the hyoid was depressed (cm). Each circle represents a mean of all feeding strikes of each individual with their mean resultant kinematic angle and mean time to peak extension.

Figure 13. Linear model illustrating the mean time (ms) it took to reach the maximum angle elevation and the mean maximum angle difference created (degree) in a feeding strike. Each circle represents a mean of all feeding strikes of each individual with their mean resultant kinematic angle and mean time to peak extension.

Figure 14. Linear model illustrating the variation in peak sub-ambient pressure (kPa) between peak pressures generated (kPa) from all individuals and the mean time it took to reach man maximum extension of the gape height (ms) generated by the individual during a feeding strike. Each circle represents a mean of all feeding strikes of each individual with their resultant mean pressure (kPa) and mean time to max gape height (ms) generated of all feeding events.

Figure 15. Linear model illustrating the variation in peak sub-ambient pressure (kPa) between man peak pressures generated (kPa) from all individuals and the mean time it took to reach maximum extension of the hyoid depression (ms) generated by the individual during a feeding strike. Each circle represents a mean of all feeding strikes of each individual with their resultant mean pressure (kPa) and mean time to max hyoid depression (ms) generated of all feeding events.

Figure 16. Linear model illustrating the variation in peak sub-ambient pressure (kPa) between mean peak pressures generated (kPa) from all individuals and the mean time it took to reach maximum cranial elevation (ms) generated by the individual during a feeding strike. Each circle represents a mean of all feeding strikes of each individual with their resultant mean pressure (kPa) and mean time to max cranial elevation (ms) generated of all feeding events.

Figure 17. Boxplot illustrating the variation in peak sub-ambient pressure (kPa) between each individual and the treatment level with each bar having a standard error. The circles are individual pressures that are considered outliers.

Figure 18. Boxplot illustrating the variation in peak sub-ambient pressure (kPa) between each treatment level with each bar having a standard error. The circles are individual pressures that are considered outliers.