Oregon Undergraduate Research Journal 
5.1 (2013)  ISSN: 2160-617X (online) 
http://journals.oregondigital.org/ourj/ 
DOI: 10.5399/uo/ourj.5.1.3241 
 
 
*Clare Chisholm graduated with honors from the Environmental Science department in Spring 2013. While at the 
University of Oregon, she also completed minors in Biology and Latin American Studies. 
Prey Detection and Feeding Success of the Comb 
Jellyfish Mnemiopsis leidyi on Copepods in Still and 
Turbulent Waters 
Clare Elizabeth Chisholm*, Environmental Science 
ABSTRACT 
The comb jelly or ctenophore, Mnemiopsis leidyi, is a voracious predator in both its 
native and non-native habitats. Though M. leidyi inhabits coastal waters that are 
frequently turbulent, previous feeding studies have been conducted in still water 
tanks. This study aimed to research feeding behaviors in turbulent waters, which is 
more representative of the natural environment. Interactions between the free-
swimming ctenophores and copepod prey, such as Acartia tonsa, were observed and 
recorded in a laboratory turbulence tank (n = 73). Turbulence was created using 
submersible speakers, and the interactions were recorded using a video camera.  
Capture efficiency denoted interactions containing direct contact between copepods 
and M. leidyi that led to eventual capture, frequently after multiple contacts. Overall 
copepod capture efficiency was similar in still (48%) and turbulent (43%) water, as were 
the overall prey retention rates for each (still = 58%; turbulent = 57%). However, M. 
leidyi exhibited anticipatory responses, defined as altering the position of feeding 
structures, nearly twice as often in still (41%) waters than in turbulent (20%) waters. 
The hydromechanical “noise” produced by background turbulence may inhibit the 
capacity of the ctenophore to detect and respond to fluid motions produced by its 
prey. 
 
1. INTRODUCTION 
The lobate ctenophore Mnemiopsis leidyi is a planktonic predator native to the Atlantic 
coastal waters of North and South America, ranging from Buzzards Bay, USA (40ºN) to Bianca 
Bay, Argentina (46ºS) (Fig. 1; Colin et al., 2010; Mianzan et al., 2010; Costello et al., 2012). 
Ecologically important to its native range, M. leidyi has also become ecologically important in its 
invasive range, mainly due to its rapid population growth rates and high feeding rates on 
zooplankton and ichthyoplankton (Costello et al., 1999; Colin et al., 2010; Costello et al., 2012). 
In the last 30 years, M. leidyi has transitioned from its native waters to the Black Sea, Caspian 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  23 
Sea, Mediterranean Sea, North Sea, Baltic Sea, Sea of Azov, Sea of Marmara and the Adriatic Sea 
(Bright, 1999; Mutlu 1999; Finenko et al., 2006; Roohi et al., 2008; Colin et al., 2010; Costello et 
al., 2012). Introduced to these areas in the 1980s, it is likely that M. leidyi first invaded the Black 
Sea via ballast water and spread to the surrounding ecosystems (Mutlu 1999; Finenko et al., 
2006; Roohi et al., 2008; Ghabooli et al., 2010, Costello et al., 2012). Due to the ctenophores 
self-compatible hermaphroditism, its tolerance to a range of temperatures, salinity and oxygen 
levels and its extensive dietary plasticity, M. leidyi has established itself as a prolific invader 
(Roohi et al., 2008; Ghabooli et al., 2010; Mianzan et al., 2010). Additionally, the invasion and 
explosion of M. leidyi in the European seas has been identified as a possible cause to of the 
collapse of fisheries in Eurasia, including that of economically important fish species, such as 
anchovies (Bilio and Niermann, 2004; Daskalov & Mamedov, 2007; Costello et al., 2012). 
When observed feeding in still water environments, M. leidyi engages the ciliary lining in the 
auricles, creating a laminar feeding current (Fig. 2; Colin et al., 2010). This current causes large 
quantities of fluid to be swept between the oral lobes, allowing the ctenophore to entrain and 
retain prey very efficiently (Colin et al., 2010). This capacity to process large volumes of water 
has greatly contributed to the ecological success of the species, and is likely one of the primary 
influences on the devastation of planktonic communities (Mutlu, 1999; Finenko et al., 2006; 
Colin et al., 2010). 
Information gathered in relation to the feeding habits of M. leidyi has been primarily 
conducted in still water settings; however, water movement frequently characterizes the natural 
ecological habitats of M. leidyi. Previous research has discovered that M. leidyi has a 74% 
success capture rate after contact occurs between predator and prey. However, capture success 
numbers fall substantially when initial contact between species occurs on the interior surface of 
the oral lobes (Costello et al., 1999). This is likely because physical contact with the oral lobe of 
the ctenophore elicits an escape response from the copepod.  Considering the importance of 
fluid manipulation during feeding, background water motion is a likely influence on the 
predation behaviors of M. leidyi  
  Turbulence is defined as the time-varying movement of water, which can be produced by 
wind, waves, tides, coastal upwelling and the interaction with rough surface; then disperses 
heat, particles and organisms throughout the ocean (Robinson et al., 2007; Thorpe, 2007). 
Turbulence, being the natural state of the oceanic environment, often evokes variant responses 
in marine organisms such as copepods and ctenophores (Warnaars et al., 2006; Thorpe, 2007). 
Planktonic organisms have evolved in the presence of fluid motion and are able to detect and 
respond to turbulence and related fluid-mechanical cues (Warnaars et al., 2006; Thorpe, 2007). 
For the purpose of this research, turbulence was studied in relation to the interactions between 
M. leidyi and copepods. Copepods employ sensory hairs on their antennae called setae in order 
to detect changes in ambient turbulence (Kiorboe, 2008).  Evidence exists that copepods are 
capable of distinguishing the differences between environmental fluid motion cues and the cues 
from other plankters; ambient turbulence does not necessarily elicit the bending of the setae of a 
copepod, which dictate whether an attack or escape response is appropriate (Kiorboe, 2008). In 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  24 
contrast, the disturbance of water movement by predators, such as M. leidyi, may induce these 
responses from copepod individuals (Kiorboe, 2008). 
The goal of this study was to compare the predator-prey encounters and feeding success 
rates of the adult M. leidyi on copepods in still and turbulent conditions. In both treatments, 
encounters between copepods and M. leidyi individuals were quantified to document the 
relationship between feeding success in turbulent vs. non-turbulent water. In particular, the 
following hypothesis was tested: 
H0: Increased turbulence has no effect on the success of the predator-prey interaction 
between Mnemiopsis leidyi and zooplankton species in terms of retention and capture 
efficiencies 
H1: An increase in turbulence causes an increase in the retention and capture efficiencies of 
Mnemiopsis leidyi when feeding on zooplankton species 
 It was expected that retention and capture efficiencies would increase with increased 
turbulence due to the amplified noise within ambient waters. Theoretically, this would allow for 
M. leidyi individuals to ambush prey more effectively, and retain prey more efficiently (Costello 
et al., 1999). 
2. MATERIALS AND METHODS 
2.1 COLLECTION 
Specimens of the ctenophore Mnemiopsis leidyi and zooplankton prey were collected in 
August of 2011 at the Marine Biological Labs (MBL) in Woods Hole, Massachusetts. Ctenophore 
specimens between 2 and 4 cm were dipped from the surface water using beakers. Individuals 
were held in tanks of ambient seawater and observed within 24 hours of collection. Additionally, 
zooplankton were collected, primarily Acartia tonsa, using a 0.5 meter plankton net with 333 
micrometer mesh.  
2.2 TURBULENCE 
Ctenophore-copepod interactions were observed at three flow levels: still water, 
intermediate turbulence (24 and 27 clicks) and high turbulence (30 clicks). Turbulence was 
generated following the methods of Warnaars et al (2006). A rectangular tank with a removable 
lid was designed out of Plexiglass (dimensions = 26 x 50 x 30 cm), with plastic mesh grids with 
1-2 cm openings placed at opposite ends. Submersible speakers (Clark Synthesis AQ339) were 
connected to an amplifier and mounted behind the mesh grids at each end of the tank. 
Turbulence was produced using low frequency (30 Hz), out-of-phase (180°) sine waves that 
were generated using a computer program called “Test Tone Generator.” The alternation of the 
sine waves allowed the water to be pushed back and forth, which simulated energy dissipation 
levels in the natural environment. 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  25 
Each speaker was then turned to a specific volume, 0 clicks for still water, 24 and 27 clicks 
for intermediate turbulence, and 30 clicks for high turbulence. Clicks simply denoted the 
volume level of the speaker. The overall turbulence dissipation rate of the pooled data is as 
follows: mean ± SD = 3.75 x 10-7 ± 2.99 x 10-7 m2s-3. This number can be compared to rates of 
turbulence dissipation measured at the ocean surface and in estuaries. Usually, the surface rates 
are less than 1 x 10-6 m2s-3, and estuaries can reach 1 x 10-3 m2s-3, though they rarely encounter 
these sorts of levels (Noh and Hyoung, 1999). 
2.3 VIDEOGRAPHY 
For each trial, 5-8 individual M. leidyi were introduced to the turbulence generator and 
allowed to acclimate for a minimum of 10 minutes. Interactions between M. leidyi and copepod 
prey were then filmed using a Sony HDR-HC9 handheld video camcorder, stabilized on a tripod. 
The tank was lit using LED lights, and the movement of individual specimens was tracked with 
the camera. Scale bars were included within the recording periodically, in order to provide 
spatial context for the interactions. The total film time was approximately 3 hours and 44 
minutes. 
2.4 VIDEO ANALYSIS 
Video analysis was conducted using the film-editing software iMovie 2009 (Apple Inc., 
version 8.0.6). Videos were observed carefully to identify interactions between M. leidyi and 
copepod individuals. Video segments encompassing encounters between M. leidyi and copepods 
spanning five seconds or greater were selected for data collection. During the five-second clips, a 
minimum of 75% of the ctenophore body was required to be within the entire frame as well as 
the interacting copepod individual. Additionally, the segments could not have more than one M. 
leidyi specimen within the frame. Video clips involving an interaction were subsequently 
analyzed and components of the predation process were coded following the methods of 
previous studies regarding M. leidyi predation behaviors (Costello et al., 1999); encounters were 
analyzed based on the following predation sequence: 
 
 
 
Each component is described in Table 1. Similar to research conducted by Costello et al. (1999), 
the two variables evaluated were retention and capture efficiency, which were defined in as the 
following: 
Encounter Contact Capture Ingestion 
Escape Escape 
 
Retention Efficiency no. of x10
Capture Efficiency no. of no. of x10	
   
no. of 	
   
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  26 
 The two efficiencies quantify two key elements of the encounters. Retention efficiency 
evaluates the ability of the ctenophore to retain prey post-contact. Comparatively, capture 
efficiency quantifies the final post-encounter outcome of M. leidyi and zooplankton individuals, 
disregarding intermediate interactions between the two species. Retention and capture 
efficiencies were calculated using the aforementioned equations and then statistically analyzed 
for significance using a chi-square test (Microsoft Excel for Mac 2011, Version 14.3.2). 
3. RESULTS 
3.1 RETENTION AND CAPTURE EFFICIENCY 
A total of 73 encounters were observed between Mnemiopsis leidyi and copepods during the 
study. Of these encounters 29 occurred in still water and 44 occurred in turbulent water. 
Retention efficiency for still and turbulent waters was similar (Fig. 3). In still water, the 
retention rate was 58.3%, and turbulent water interactions exhibited a retention rate of 57.6%. 
Capture efficiencies between treatments varied more than retention efficiencies, though 
there was no significant difference. Interactions occurring in still water had a capture rate of 
48.3%, while turbulent treatments resulted in a capture rate of 43.2%  (X2 = 0.124, df = 1, p = 
0.724). 
3.2 VARIATIONS IN ENCOUNTER ORIGINS 
In both treatments, encounters originated through two processes: laminar flow generated by 
M. leidyi (n = 53) and movement of copepod individuals towards M. leidyi prior to interspecies 
contact (n = 20; Fig. 4). The majority of encounters in this study originated through laminar 
flow created by M. leidyi individuals, with little variation between still and turbulent treatments 
(still = 69.0%; turbulent = 70.5%). Less than half of the encounters began with pre-contact 
motion by the copepod prey, again with little difference between the two treatments (still = 
31.0%; turbulent = 29.6%). No significant difference existed between still and turbulent 
encounter origins (X2 = 0.052, df = 1, p = 0.820). 
3.3 ENCOUNTERS AND CONTACT RELATIONSHIP 
The majority of interactions between the ctenophore M. leidyi and copepods involved 
multiple contacts. Overall, encounters with multiple contacts (n = 45) occurred more than twice 
as often as interactions containing single contacts (n = 23; Fig. 5). Additionally, interactions in 
turbulent waters containing multiple contacts (42.6%) occurred nearly twice as often as 
encounters with multiple contacts in still waters (23.5%). Despite these differences in frequency, 
there was no significant difference in contact frequency between still and turbulent treatments 
(X2 = 0.124, df = 1, p = 0.724). 
Encounters with and without anticipation were evaluated based on the number of contacts 
within each interaction. When anticipation was not present (Fig. 6), encounters in turbulent 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  27 
waters occurred more often, both with single (28.6%) and multiple contacts (33.3%).  The 
proportion of encounters with single contacts in still water was 11.9%, less than half that of 
turbulent encounters. Additionally, in still water encounters without anticipation, multiple 
contacts (26.2%) occurred more than twice as frequently as single contacts. However, when the 
treatments were compared, no significant difference between proportion of encounters and 
contact number was seen in still vs. turbulent waters (X2 = 2.249, df = 1, p = 0.134). 
In contrast, anticipation occurred more often in still waters, including encounters containing 
single (26.7%) and multiple (33.3%) contacts (Fig. 7). While an increase from single contact to 
multiple contacts with anticipatory behaviors was seen, no significant difference was exhibited 
(X2 = 1.238, df = 1, p = 0.266). In addition, interactions with anticipatory movement and 
multiple contacts (26.8%) occurred more often than single contacts (13.3%) in turbulent waters. 
3.4 PREY DETECTION AND PREDATION SUCCESS 
The ctenophore M. leidyi frequently employs anticipatory behaviors upon the detection of 
nearby prey. In still waters, anticipatory movements were displayed by the ctenophore 41.4% of 
the time (Fig. 8). In contrast, in turbulent waters anticipatory behaviors were exhibited in only 
20.5% of the interspecies encounters. However, when no anticipatory movement was present 
the proportion of encounters between M. leidyi and copepods displayed a large increase 
(79.6%). A higher proportion of encounters occurred in still water without anticipatory 
movement (58.6%) than with anticipatory movement. There was a significant difference 
between interactions with anticipatory behavior and those without anticipatory behavior in still 
and turbulent water (X2 = 10.256, df = 1, p = 0.001). 
The capture efficiency of encounters with and without anticipatory movements in still and 
turbulent waters displayed opposing trends (Fig. 9). For still water interactions the capture 
efficiency of M. leidyi was higher when an anticipatory motion was present (27.6%), and lower 
without anticipatory behavior (20.7%). In contrast, M. leidyi experienced greater capture 
efficiency success when no anticipatory behavior was present in turbulent waters (31.8%), and a 
much lower rate of capture efficiency when anticipatory behaviors were present (11.4%). 
Additionally, when capture efficiency and presence of anticipatory behavior was compared 
between still and turbulent treatments a significant difference was observed (X2 = 9.342, df = 1, 
p = 0.002). 
4. DISCUSSION 
4.1 RETENTION AND CAPTURE EFFICIENCY 
As previously discussed, encounters between Mnemiopsis leidyi and copepods were 
analyzed in both turbulent and still water. It was expected that retention and capture efficiencies 
would be lower in still waters than in turbulent waters. However, similarities in retention and 
capture efficiencies between treatments were observed, suggesting that M. leidyi appears to be 
an equally effective predator on copepods in both still and turbulent waters. 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  28 
While this relationship was unexpected, it led to additional questions and observations 
regarding ctenophore feeding behaviors. It is possible that M. leidyi employed different 
predatory tactics within the two treatments, allowing individuals to detect and consume prey 
efficiently in both still and turbulent environments. These varying behaviors could include 
anticipatory movements, altered body positioning and selective feeding based on copepod life 
stage (Costello et al., 1999; Waggett and Costello, 1999). Previous studies have indicated that M. 
leidyi preferentially select late-stage and larger copepods over early-stage and smaller copepods 
when employing anticipatory behaviors (Costello et al., 1999; Waggett and Costello, 1999). 
4.2 ENCOUNTER ORIGINS AND FREQUENCY OF M. LEIDYI ANTICIPATION 
The origin of encounters between M. leidyi and copepods varied little between still water 
and turbulent water treatments. In both treatments, laminar flow was most often employed by 
the ctenophore, in order to entrain copepods. In contrast, prey motion much less frequently 
served as the point of origin for ctenophore-copepod interactions. These results did not correlate 
with previous research, as earlier studies displayed that the majority of encounters began with 
prey motion (Costello et al., 1999). However, these studies observed interactions between the 
adult-stage copepod Acartia tonsa and late-stage M. leidyi individuals (Costello et al., 1999; 
Waggett and Costello, 1999). The study performed by Costello et al. (1999) found that more 
frequently swimming by adult A. tonsa led to the interspecies encounters, but interactions 
between the smaller copepods Oithona colcarva were usually initiated by the laminar flow 
produced by M. leidyi 
It is possible that the variation between results of this study and the results of the previous 
studies is due to the disparity in copepod life-history stage and species. While the majority of 
copepods in this study were identified as A. tonsa it is likely that several of these were A. tonsa 
nauplii individuals, which are substantially smaller than their adult counterparts. Additionally, 
it has been observed that A. tonsa nauplii cause a reduced disturbance in surrounding fluid 
when compared to adult-stage A. tonsa, causing the ctenophore to employ entrainment through 
flow when feeding on smaller individuals (Costello et al. 1999; Waggett and Costello, 1999). 
These factors led to the conclusion that the high frequency of encounters observed in this study 
originating with laminar flow are likely due to the increased presence of the smaller A. tonsa 
nauplii. 
In addition to employing laminar flow more frequently, M. leidyi individuals in this study 
also seldom exhibited anticipatory movements in either still or turbulent treatments. Again, 
these data contradict the findings of previous studies, which found that anticipatory behavior 
was often exhibited in still waters (Costello et al., 1999). Similarly, these differing results 
regarding anticipatory behavior may be linked to the size of the copepods present (Costello et 
al., 1999; Waggett and Costello, 1999). In their study, Costello et al., (1999) observed that A. 
tonsa nauplii rarely elicited an anticipatory response from M. leidyi, likely due to their 
decreased disturbance to the background water motion. These slow-moving, small prey are far 
more likely to be entrained by the laminar flow generated by M. leidyi (Waggett and Costello, 
1999). 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  29 
4.3 INTERSPECIES CONTACT AND ANTICIPATION 
The majority of encounters in this study involved multiple contacts between species, 
regardless of still or turbulent treatments. However, a larger proportion of encounters in 
turbulent water demonstrated multiple contacts when compared to still treatments. 
Additionally, encounters containing multiple contacts in turbulent waters also occurred more 
frequently than encounters exhibiting single contacts in turbulent waters. This is possibly due to 
a lack of prey detection in turbulent waters, and the multiple contacts followed before M. leidyi 
could effectively capture the prey. Additionally, similar to the results of Costello et al. (1999) the 
bulk of escapes by copepods in this study occurred when a single contact was present, regardless 
of still or turbulent conditions. 
In addition to the proportion of encounters with single and multiple contacts, the 
relationship between contact number and presence of anticipatory behaviors was analyzed. 
Similar to previous studies, an increase in encounters with multiple contacts and anticipation 
were observed in both still and turbulent waters (Costello et al., 1999). However, contradicting 
trends were seen in encounters exhibiting no anticipation. Earlier research found that 
interactions without anticipation exhibited a single contact the majority of the time, and 
infrequently had multiple contacts (Costello et al., 1999). While encounters in turbulent waters 
may display these opposing results due to the difference in background water motion, it is likely 
that encounters in still water differ based on prey species and size once again (Costello et al., 
1999; Waggett and Costello, 1999). 
As M. leidyi continues to expand its native and non-native range, knowledge surrounding its 
feeding behaviors is increasingly important. This research provides further information 
regarding the predation tactics and interactions of M. leidyi with copepods, such as A. tonsa, in 
a system replicate of its natural environment. It is possible that M. leidyi has shown itself to be 
such an effective invasive species because it successfully feeds on small prey, though it 
selectively anticipates larger prey (Costello et al., 1999; Waggett and Costello, 1999). 
Continued examination of the feeding behaviors of M. leidyi in relation to varying 
environmental factors, such as salinity, temperature and life stage of prey and predator, would 
be beneficial in the understanding of the species’ invasive tendencies. Additionally, research on 
other lobate ctenophore species may also provide insight into their influence on zooplankton 
communities. It remains clear that ctenophores, and M. leidyi specifically, play an important 
ecological role in the global food webs. Their consumption of species existing on some of the 
lowest trophic levels allows M. leidyi to substantially impact both native and non-native 
ecosystems. 
ACKNOWLEDGEMENTS 
I would like to thank my advisor Dr. Kelly Sutherland for providing data and guiding me 
throughout the entirety of my thesis. Dr. Sutherland’s support was invaluable, and I would have 
been unable to complete this thesis without her. I would also like to thank my academic advisor 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  30 
Peg Boulay and the Environmental Science department at the University of Oregon for the 
extensive opportunities and support throughout my undergraduate education. Dr. Sutherland 
was provided funding for sample collection by a grant from the National Science Foundation. All 
research was collected at the Woods Hole Marine Biological Labs and analyzed at the University 
of Oregon.  
REFERENCES 
Bilio, M., and U. Niermann. "Is the comb jelly really to blame for it all? “Mnemiopsis leidyi and 
the ecological concerns about the Caspian Sea." Marine Ecology Progress Series. 269. 
(2004): 173-183. 
Colin, S. P., J.H. Costello, L.J. Hansson, J. Titelman, and J.O. Dabiri. "Stealth predation and the 
predatory success of the invasive ctenophore Mnemiopsis leidyi." Proceedings of the 
National Academy of Sciences. 107.40 (2010): 17223–17227. 
Costello, J.H., K.M. Bayha, H.W. Mianzan, T.A. Shiganova, and J.E. Purcell. "Transitions of 
Mnemiopsis leidyi (Ctenophora: Lobata) from a native to an exotic species: a review." 
Hydrobiologia. 690. (2012): 21-46. 
Costello, J.H., R. Loftus, and R. Waggett. "Influence of prey detection on capture success for the 
ctenophore Mnemiopsis leidyi feeding upon adult Acartia tonsa and Oithona colcarva 
copepods." Marine Ecology Progress Series. 191. (1999): 207-216. 
Daskalov, G.M., and E.V. Mamedov. "Integrated fisheries assessment and possible causes for the 
collapse of anchovy kilka in the Caspian Sea." Journal of Marine Sciences. 64. (2007): 503-
511. 
Finenko, G.A., A.E. Kideys, B.E. Anninsky, T.A. Shiganova, A. Roohi, M.R. Tabari, H. Rostami, 
and S. Bagheri. "Invasive ctenophore Mnemiopsis leidyi in the Caspian Sea: feeding, 
respiration, reproduction and predatory impact on the zooplankton community." Marine 
Ecology Progress Series. 314. (2006): 171-185.. 
Kiorboe, T. A Mechanistic Approach to Plankton Ecology. 1st ed. 1. Princeton: Princeton 
University Press, 2008. 83-98. Print. 
Mianzan, H.W., P. Martos, J.H. Costello, and R.A. Guerrero. "Avoidance of hydro-dynamically 
mixed environments by Mnemiopsis leidyi (Ctenophora: Lobata) in open-sea populations 
from Patagonia, Argentina." Hydrobiologia. 645. (2010): 113-123. 
Mutlu, E. "Distribution and abundance of ctenophores and their zooplankton food in the Black 
Sea. II. Mnemiopsis leidyi." Marine Biology. 135. (1999): 603-613. 
Robinson, H.E., C.M. Finelli, reef on their ability to detect and evade predators." Marine 
Ecology Progress Series. 349. (2007): 171-181. 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  31 
Roohi, A., Z. Yasin, A.E. Kideys, A.T. Shau Hwai, A.G. Khanari, and E. Eker-Develi. "Impact of a 
new invasive ctenophore (Mnemiopsis  leidyi) on the zooplankton community of the 
Southern Caspian sea." Marine Ecology. 29. (2008): 421-434. 
Shiganova T.A.  “Ctenophore Mnemiopsis leidyi (A.Agassiz) in the Azov and Black Sea and 
consequences of its intrusion.” Rostov-on-Don. (2000): 33-75. 
Thorpe, S.A. An Introduction to Ocean Turbulence. 1st ed. 1. Cambridge: Cambridge University 
Press, 2007. 1-152. Print. 
Waggett, R., and J.H. Costello. "Capture mechanisms used by the lobatectenophore, 
Mnemiopsis leidyi, preying on the copepod Acartia tonsa." Journal of Plankton Research. 
21.11 (1999): 2037-2052.  
Warnaars, T.A., M. Hondzo, and M.A. Carper. "A desktop apparatus for studying interactions 
between microorganisms and small-scale fluid motion." Hydrobiologia. 563. (2006): 431-
443.443. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  32 
TABLES AND FIGURES 
 
Variable Description 
Encounter Interaction between ctenophore and copepod within the encounter zone, 
initiated either by direct contact between ctenophore and copepod or by an 
anticipatory response (e.g. oral lobe folding) by ctenophore prior to 
contact with copepod. The encounter zone was defined as the area 
bounded on the sides by the interior lobes of the ctenophore and extending 
anterior to the lobes for 3 mm (approximately 2 Acartia tonsa body 
lengths). Encounters terminated in either an escape from the encounter 
region or capture of the copepod by the ctenophore 
Encounter origin Means of encounter initiation; either flow entrainment or self-propelled 
swimming by the copepod. Copepod motion relative to surrounding flow 
was readily confirmed by visually comparing copepod velocities with 
those of surrounding particles entrained within flow field 
Contact Physical collision of predator and prey bodies. An encounter could entail 
multiple contacts if the copepod was not retained and collided with 
another portion of the ctenophore's capture surfaces. Contacts with 
exterior portions of the ctenophore's body (e.g. lobe exterior) were not 
recorded as contacts because these could not result in capture and were 
outside the encounter zone 
Escape Evasion of capture by a copepod after encounter with a ctenophore; the 
copepod must have left the encounter zone. Contact was not required 
Capture Copepod subdued and consumed by ctenophore 
Anticipatory response Lobe or auricle motion of ctenophore in response to copepod prior to 
actual contact 
Prey motion Motion of copepod prey in the vicinity of the ctenophore prior to contact 
Number of contacts Number of contacts between the ctenophore and copepod during an 
encounter 
Encounter outcome Capture or escape of a copepod as a result of an encounter 
Table 1 Patterns of copepod-ctenophore encounters (Costello et al., 1999). 
 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  33 
 
Figure 1 Map of the native and invasive ranges of Mnemiopsis leidyi. The black line represents the native range 
of the species and the red represents the invasive territory. 
Figure 2 Mnemiopsis leidyi. (1) aboral organ, (2) subtentacular row of comb flappers, (3) subsagital row of 
comb flappers, (4) auriculus, (5) subsagital tube, (6) translobal tube, (7) tentacular tube, (8) lobe (Shiganova, 
2000).As compared to 2011, the 2012 sediment size distribution in Middle McKenzie side channel 4 shifted 
toward a smaller median pebble size with an increase in D84 in count 1, while median pebble size increased with 
no detectable change in D84 values for count 2 (Figure 2). For count 1, the D50 size class decreased from 45-64 
mm to a size class of 32-45 mm and the D84 size class increased from 91-128 mm to 128-181 mm. For count 2, the 
D50 size class increased from 32-45 mm to 45-64 mm and the D84 size class was recorded at 91-128 mm both 
years.  
 
 
 
 
 
 
 
 
 
 
 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  34 
 
Figure 3 Retention and capture efficiencies of encounters between Mnemiopsis leidyi and copepods that 
occurred in still (n = 29) and turbulent (n = 44) waters.  
  
Figure 4 Origin of encounters between Mnemiopsis leidyi and copepods in still and turbulent water treatments. 
Encounters began with either entrainment by M. leidyi (laminar flow) or independent movement by copepods 
(prey motion).  
 
 
0 
10 
20 
30 
40 
50 
60 
70 
Retention Capture 
E
ffi
ci
en
y 
(%
) 
Still 
Turbulent 
0 
10 
20 
30 
40 
50 
60 
70 
80 
Laminar Flow Prey Motion 
Pr
op
or
tio
n 
of
 E
nc
on
te
rs
 (%
) 
Encounter Origin 
Still 
Turbulent 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  35 
 
Figure 5 Frequency of encounters containing single and multiple contacts between Mnemiopsis leidyi 
and copepods in still (n = 25) and turbulent (n = 43) waters. 
 
 
 
Figure 6 Encounters between copepods and Mnemiopsis leidyi individuals exhibiting no anticipatory 
behaviors with single or multiple contacts. Still (n = 16) and turbulent (n = 26) treatments were 
compared. 
 
 
 
 
 
 
 
 
 
0 
5 
10 
15 
20 
25 
30 
35 
40 
45 
Single Multiple P
ro
pp
or
tio
n 
of
 E
nc
ou
nt
er
s (
%
) 
Number of Contacts 
Still 
Turbulent 
0 
5 
10 
15 
20 
25 
30 
35 
Single Multiple 
Pr
op
po
rt
io
n 
of
 E
nc
ou
nt
er
s (
%
) 
Number of Contacts 
No Anticipation 
Still 
Turbulent 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  36 
Fig. 7 Encounters between copepods and Mnemiopsis leidyi individuals exhibiting anticipatory 
behaviors with single or multiple contacts. Still (n = 9) and turbulent (n = 6) treatments were compared. 
 
 
 
 
 
 
 
Fig. 8 Proportion of encounters between Mnemiopsis leidyi and copepods containing anticipatory 
behaviors in still (n = 29) and turbulent waters (n = 44). 
 
 
 
 
 
 
 
 
 
 
 
0 
10 
20 
30 
40 
50 
60 
70 
80 
90 
Anticipation No Anticipation 
Pr
op
or
tio
n 
of
 E
nc
ou
nt
er
s (
%
) 
Still 
Turbulent 
0 
5 
10 
15 
20 
25 
30 
35 
Single Multiple 
Pr
op
or
tio
n 
of
 E
nc
ou
nt
er
s (
%
) 
Number of Contacts 
With Anticipation 
Still 
Turbulent 
Oregon Undergraduate Research Journal  Chisholm 
Volume 5 Issue 1 Fall 2013  37 
 
Fig. 9 Capture efficiency of the ctenophore Mnemiopsis leidyi when feeding on copepods in encounters 
containing anticipatory behaviors in still (n = 29) and turbulent waters (n = 44). 
 
0 
5 
10 
15 
20 
25 
30 
35 
Anticipation No Anticipation 
C
ap
tu
re
 E
ffi
ci
en
cy
 (%
) 
Still 
Turbulent