Capture and digestion of the scyphozoan jellyfish Aurelia aurita by Cyanea capillata and prey response to predator contact

Laboratory experiments, field observations and manipulativefield experiments were carried out in 1993 in Gullmarsfjorden(Sweden) to study the interactions between two common speciesof scyphozoan jellyfish. Cyanea capillata was a predator onAurelia aurita. Gut analyses on 70 specimens of C.capillatashowed no size dependency in the ability to catch     

Effects of climate warming on strobilation and ephyra production of North Sea scyphozoan jellyfish

Recent studies have correlated fluctuations in jellyfish abundances with climatic changes, leading to speculation that the warming trend in the North Sea will affect the strobilation activity of Scyphozoa. The present study provides long-term data (10–22 months) on temperature effects on the species Aurelia aurita, Cyanea capillata, Cyanea lamarckii and Chrysaora hysoscella. Strobilation at current winter temperature (5°C) in the German Bight was compared to strobilation at warmer winter temperatures. Simulated winter temperature of 10°C had several positive effects on strobilation, as compared to 5°C: 1. A longer strobilation period or higher ephyra production per polyp in A. aurita, C. lamarckii and Ch. hysoscella; 2. Higher percentages of polyps strobilating in A. aurita and Ch. hysoscella; 3. More ephyrae per strobila in C. capillata and C. lamarckii; 4. A shorter strobilation duration in C. capillata and C. lamarckii. Cold winter temperatures of 5°C promoted strobilation in C. capillata, but inhibited strobilation in A. aurita and reduced ephyra production in C. lamarckii and Ch. hysoscella. These results suggest that climate warming will benefit A. aurita, but not cold-water C. capillata. The distributions of C. lamarckii and Ch. hysoscella probably could expand to the north.     

Effects of low salinity on settlement and strobilation of scyphozoa (Cnidaria): Is the lion’s mane <Emphasis Type="Italic">Cyanea capillata</Emphasis> (L.) able to reproduce in the brackish Baltic Sea?

Several species of scyphozoan medusae occur in river estuaries and other brackish waters but it is often unknown if the planulae settle and the scyphopolyps reproduce in those low-salinity waters. In the present study, scyphozoan species from the German Bight (North Sea) were tested in laboratory experiments to investigate their tolerance of low salinity. Planula larvae released from medusae in salinity 32 were still active after the salinity was reduced to 10 (Cyanea capillata, Cyanea lamarckii) and to 7 (Chrysaora hysoscella) in laboratory treatments. Planulae did not settle on the undersides of floating substrates when salinity was reduced to <20. By contrast, planulae released from C. capillata medusae in Kiel Bight (western Baltic Sea) in salinity 15 developed into polyps in laboratory cultures. Polyps reared from planulae in salinity 36 survived a reduction to 12 (C. capillata, C. lamarckii) and to 8 (Aurelia aurita). Polyps of all tested species strobilated and released young medusae (ephyrae) in salinity 12. These results show a high tolerance of planulae and polyps to low salinity, indicating their possible occurrence in estuaries and brackish waters. In addition to laboratory observations, young C. capillata ephyrae were collected in the western Baltic Sea (Kiel Bight) in salinity 15, which indicates that they were probably released by a local polyp population. We suggest that the polyps of the painfully stinging lion’s mane, C. capillata, may be more widespread in the Baltic Sea than previously assumed and that the occurrence of the medusae may not only depend on inflow of water masses from the North Sea.     

Behavioural response of the scyphozoan jellyfish Aurelia aurita (L.) upon contact with the predatory jellyfish Cyanea capillata (L.)

Underwater manipulative experiments were carried out in situ to investigate the sensibility of the jellyfish Amelia aurita (L.) to contact with the tentacles of Cyanea capillata (L), commonly known as a predator on A. aurita. Movements of individual medusae touched by tentacles of C. capillata and other objects were video‐recorded during SCUBA dives. The behavioural variable studied was change in swim pulse frequency. The results showed that A. aurita was highly susceptible to the tentacles of C. capillata and responded with an increased swim pulse frequency when touched at the umbrellar margin but not at the central exumbrella. Contact with other objects also induced a behavioural response in A. aurita.     

Selective toxin-lipid membrane interactions of natural, haemolytic Scyphozoan toxins analyzed by surface plasmon resonance

A comparison of the molecular interaction of natural Scyphozoan lysins with their bioactivity in a haemolytic assay was performed by establishing an efficient, automatable and reproducible procedure for the measurement of protein-membrane interactions. The toxin-membrane interactions were analyzed utilising a chip-based technology with immobilized liposomes as artificial cell membranes. The technique was established with streptolysin O as a cholesterol-selective model toxin and its cholesterol-selectivity has been proven. The haemolytic potency of protein fractions derived from the venom of the jellyfish Aurelia aurita and Cyanea capillata was tested and EC50 values of 35.3 μg/mL and 43.1 μg/mL against sheep and 13.5 μg/mL and 8.8 μg/mL against rabbit erythrocytes were measured. Cell membrane binding as a first step in the haemolytic process was analyzed using the Biacore^® technology. Major cell membrane lipids (cholesterol, sphingomyelin and phosphatidylcholine) were immobilized as pure liposomes and in binary mixtures. A preference for cholesterol and sphingomyelin of both jellyfish species was demonstrated. The specificity of the method was proven with a non-haemolytic A. aurita protein fraction that did not express a lipid binding. Additionally, an inactivated C. capillata lysine with negligible haemolytic activity showed a remaining but reduced adsorption onto lipid layers. The binding level of the lytic venom fraction of these dominant boreal jellyfish species increased as a function of protein concentration. The binding strength was expressed in RU50 values ranging from 12.4 μg/mL to 35.4 μg/mL, which were in the same order of magnitude as the EC50 values in the haemolytic assay.     

Malate dehydrogenase and tetrazolium oxidase of scyphistomae ofAurelia aurita,Chrysaora quinquecirrha,andCyanea capillata (Scyphozoa: Semaeostomeae)

Summary 1. The malate dehydrogenase (MDH) isozyme patterns of the three most common polyps of Chesapeake Bay (USA) differ in number and in electrophoretic mobilities:Aurelia aurita: 4 bands (Rm=0.29, 0.33, 0.39, 0.43);Chrysaora quinquecirrha: 5 bands (Rm=0.21, 0.22, 0.40, 0.53, 0.54);Cyanea capillata: 1 band (Rm=0.50) or sometimes a second (Rm=0.25).2. The tetrazolium oxidase (TO) isozyme patterns differ as follows:Aurelia aurita: 2 bands (Rm=0.39, 0.51);Chrysaora quinquecirrha: 1 band (Rm=0.58);Cyanea capillata: 1 band (Rm=0.39).3. Isozyme components of MDH and TO, either singly or in combination, may be used to distinguish the common Chesapeake Bay polyps of unknown origin.

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Malatdehydrogenase und Tetrazoliumoxydase der Scyphistomae vonAurelia aurita, Chrysaora quinquecirrha andCyanea capillata (Scyphozoa: Semaeostomeae)

Kurzfassung Im Gewebe der Scyphistomae vonAurelia aurita, Chrysaora quinquecirrha undCyanea capillata wurde das Isoenzymmuster der Malatdehydrogenase (MDH) und der Tetrazoliumoxydase (TO) durch Anwendung der Polyacrylamidgel-Elektrophorese bestimmt. Entsprechend der Reihenfolge der genannten Arten betrug die Anzahl der gefundenen MDH-Isoenzymbanden 4,5 bzw. 1, während sich die der TO-Isoenzymbanden auf 2,1 bzw. 1 belief. Es wird darauf hingewiesen, daß das Isoenzymmuster für die taxonomische Zuordnung der schwer zu unterscheidenden Scyphopolypen neben anderen Merkmalen mit herangezogen werden kann.

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Contribution No. 547 from the Virginia Institute of Marine Science.     

The presence and distribution of Antho-RFamide-like material in scyphomedusae

Summary The nervous systems of the scyphomedusae Chrysaora hysoscella, Cyanea capillata and Cyanea lamarckii (Phylum Cnidaria) were stained using an antiserum against the anthozoan neuropeptide Antho-RFamide. Staining was widespread in all three species. In Chrysaora, the antiserum revealed nerve nets in the subumrella and exumbrella ectoderm, in both faces of the oral lobes, and in the endoderm lining the subumbrella and exumbrella surfaces of the gastric cavity. The most prominent staining occurred in a dense plexus of neurons in the ectoderm at the base of the tentacles. This nerve net sent projections into the subumbrella ectoderm. For the most part, staining in the two species of Cyanea was similar to that in Chrysaora, with a few exceptions. These include the presence, in Cyanea, of an obvious tentacular nerve tract and nerve nets associated with clusters of cnidocytes in the tentacles. Radioimmunoassays of extracts from Chrysaora and Cyanea lamarkii revealed that both species contain large amounts of Antho-RFamide-like material (up to 55 nmol/animal). The results indicate that Antho-RFamide-like neuropeptides are widespread in scyphomedusae.     

Environmental factors inducing the transformation of polyp into medusae in <Emphasis Type="Italic">Aurelia aurita</Emphasis> (Scyphozoa)

The transformation of polyp into medusa is one of the most interesting processes in the life cycle of cnidarians. In the polyps of the class Scyphozoa this transformation occurs in the form of strobilation, which is the transverse fission of polyps with the formation of discoidal ephyrae. At present, the endogenous regulation of strobilation in one of scyphozoans, Aurelia aurita, is being investigated by the methods of molecular biology (Fuchs et al., 2014). However, it is still unclear which key environmental factors induce this process. The main purposes of this review are to summarize the literature data on the conditions in which strobilation in A. aurita occurs in nature and in the laboratory and to try to identify the environmental factors that are most likely to play a signaling role in strobilation.     

Population biomass, feeding, respiration and growth rates, and carbon budget of the scyphomedusa Aurelia aurita in the Inland Sea of Japan

We investigated the seasonal occurrence, wet : dry : carbon: nitrogen weight ratios, population biomass, gastric pouchcontents, and rates of feeding, growth and respiration of thescyphomedusa Aurelia aurita in the central part of the InlandSea of Japan. Aurelia aurita medusae began to appear in January/Februaryas ephyrae, reached annual maximum body size in July/August,and disappeared, presumably due to death, by November. Initialslow growth in early spring was followed by a period of exponentialgrowth (mean growth rate: 0.069 d^–1) between April andJuly. In the Ondo Strait, which is characterized by strong tidalmixing, the A. aurita population (mean carbon biomass: 66.0mg C m^–3) overwhelmingly dominated the zooplankton-communitybiomass (mean biomass of micro- and mesozooplankton: 23.7 mgC m^–3) between May and early August The gastric contentanalysis revealed that A. aurita ate almost all micro- and mesozooplankters,of which small copepods were most important. On the basis ofdigestion time for small copepods (60 min) and their abundancein the gastric pouch of field-collected A. aurita, we determinedthe weight specific feeding rates and clearance rates. The formerincreases linearly with increasing copepod abundance, but thelatter was relatively constant irrespective of the food supply.We also measured the respiration rates of A. aurita and expressedthem as functions of body weight and temperature. These physio-ecologicalparameters enabled us to construct the carbon budget of theA. aurita population typical of early summer in the Ondo Strait.Predicted population-feeding rate (6.07 mg C m^–3 d^–1)was higher than the population-food requirement for both metabolismand growth (4.55 mg C m^–3 d^–1), indicating thatfood supply was sufficient to sustain the observed growth rate.This feeding rate was equivalent to 26% of micro- and mesozooplanktonbiomass, a significant impact on zooplankton.     

Cryptic diets of forage fish: jellyfish consumption observed in the Celtic Sea and western English Channel

To establish if fishes’ consumption of jellyfish changes through the year, we conducted a molecular gut-content assessment on opportunistically sampled species from the Celtic Sea in October and compared these with samples previously collected in February and March from the Irish Sea. Mackerel Scomber scombrus were found to feed on hydrozoan jellyfish relatively frequently in autumn, with rare consumption also detected in sardine Sardina pilchardus and sprat Sprattus sprattus. By October, moon jellyfish Aurelia aurita appeared to have escaped predation, potentially through somatic growth and the development of stinging tentacles. This is in contrast with sampling in February and March where A. aurita ephyrae were heavily preyed upon. No significant change in predation rate was observed in S. sprattus, but jellyfish predation by S. scombrus feeding in autumn was significantly higher than that seen during winter. This increase in consumption appears to be driven by the consumption of different, smaller jellyfish species than were targeted during the winter.     

Population dynamics of the scyphomedusa Aurelia aurita in Southampton Water

The population dynamics of the scyphomedusa Aurelia aurita inSouthampton Water is characterized. Strobilation, indicatedby the presence of 1 mm ephyrae, occurred from the end of Januaryto the middle of March. Maximum abundances of up to 8.71 m^–3occurred soon after ephyrae release, after which numbers declinedsteadily until the end of June, when the population was absentfrom Southampton Water. The residence time of 3–4 monthsis somewhat less than that reported in many other areas, includingKiel Bight and Gullmarfjord. The carbon biomass of A.auritaaccounted for 92–97% of the predominant gelatinous biomass(A.aurita, Pleurobrachia pileus and Phialidium hemisphericum)in the upper estuary, and this reached a maximum of 30.2 mgC m^–3 in May 1990 and 27.6 mg C m^–3 in June 1991.Coincident with increased water temperature and mesozooplanktonabundance during May, growth rates increased from 0.02–0.30mm day^–1 to a peak of 4.8 mm day^–1, with a maximumbell diameter of 120–140 mm reached in late May/earlyJune. Size to maturity was variable, although the smallest medusaobserved to be ‘ripe’, i.e. containing dividingeggs and planula larvae in the brood sacs on the oral arms,were 64–71 mm. Aurelia aurita is believed to be endemicto Southampton Water, but because of the double high water inthe area, short flushing rates of between 4.5 and 20 days maybe responsible for such short residence times of Aurelia medusae.The effects of strong NE winds were considered as factors governingthe distribution of medusae in years of atypical temporal abundance.     

In situ estimation of ephyrae liberated from polyps of Aurelia aurita using settling plates in Tokyo Bay, Japan

The continuous changes in the number of newly established polyps of Aurelia aurita (L.) on settling plates under natural conditions were observed from August 1998 to September 1999 in Tokyo Bay, Japan. A sharp decline in survivorship of newly settled polyps was observed within the first few days, however, survivorship of polyps settled in October increased by budding up to 399% after two months. The number of discs in each strobila varied from 1 to 6, however, most of the strobilae formed single discs. The percentage ratios of the total number of ephyrae to the initial number of polyps on settling plates were generally lower than 10%, but the highest ratio of 594.4% was estimated for the polyps settled in October. It is considered that most of the liberated ephyrae originate from the polyps settled in October in Tokyo Bay. This study suggests that the occurrence of ripe medusae with planula larvae throughout the year contributes to the success of settlement and growth of the polyp stage in Tokyo Bay.     

Role of chemical and visual cues in food recognition by leatherback posthatchlings (Dermochelys coriacea L)

We raised leatherback posthatchlings in the laboratory for up to 7 weeks to study the role of visual and chemical cues in food recognition and food-seeking behavior. Turtles were reared on a formulated (artificial gelatinous) diet and had no contact with test materials until experiments began. Subjects were presented with visual cues (a plastic jellyfish; white plastic shapes [circle, square, diamond] similar in surface area to the plastic model), chemical cues (homogenates of lion's mane jellyfish, Cyanea capillata; moon jellyfish, Aurelia aurita; and a ctenophore, Ocyropsis sp., introduced through a water filter outflow), and visual and chemical cues presented simultaneously. Visual stimuli evoked an increase in swimming activity, biting, diving, and orientation toward the object. Chemical cues elicited an increase in biting, and orientation into water currents (rheotaxis). When chemical and visual stimuli were combined, turtles ignored currents and oriented toward the visual stimuli. We conclude that both cues are used to search for, and locate, food but that visual cues may be of primary importance. We hypothesize that under natural conditions turtles locate food visually, then, as a consequence of feeding, associate chemical with visual cues. Chemical cues then may function alone as a feeding attractant.     

Effects of temperature and light intensity on asexual reproduction of the scyphozoan, <Emphasis Type="Italic">Aurelia aurita</Emphasis> (L.) in Taiwan

Jellyfish blooms cause problems worldwide, and they may increase with global warming, water pollution, and over fishing. Benthic polyps (scyphistomae) asexually produce buds and small jellyfish (ephyrae), and this process may determine the population size of the large, swimming scyphomedusae. Environmental factors that affect the asexual reproduction rates include food, temperature, salinity, and light. In this study, polyps of Aurelia aurita (L.), which inhabit Tapong Bay, southwest Taiwan, were tested in nine combinations of temperature (20, 25, 30°C) and light intensity (372, 56, and 0 lux) in a 12 h light–12 h dark photoperiod. Production of new buds decreased with warmer temperature and stronger light intensity. Warm temperature accelerated strobilation and increased the daily production of ephyrae. The proportion of ephyrae of total asexual reproduction (new buds + ephyrae) increased dramatically in warmer temperature and more light. Survival was reduced in the highest temperature. Strobilation did not occur in the lowest temperature in darkness. All measures of total asexual reproduction indicated that mid- to high temperatures would lead to faster production of more jellyfish. Continuous high temperatures might result in high polyp mortality. Light affected asexual reproduction less than did temperature, only significantly accelerating the strobilation rate. Because the interactive effects of light and temperature were significant for the time period polyps survived and the potential production of jellyfish polyp⁻¹, combined light and temperature effects probably are important for strobilation in situ. Guest editors: K. A. Pitt & J. E. Purcell Jellyfish Blooms: Causes, Consequences, and Recent Advances     

Induction of metamorphosis from the larval to the polyp stage is similar in Hydrozoa and a subgroup of Scyphozoa (Cnidaria, Semaeostomeae)

Larvae of cnidarians need an external cue for metamorphosis to start. The larvae of various hydrozoa, in particular of Hydractinia echinata, respond to Cs⁺, Li⁺, NH₄ ⁺ and seawater in which the concentration of Mg²⁺ ions is reduced. They further respond to the phorbolester, tetradecanoyl-phorbol-13-acetate (TPA) and the diacylglycerol (DAG) diC8, which both are argued to stimulate a protein kinase C. The only well-studied scyphozoa, Cassiopea spp., respond differently, i.e. to TPA and diC8 only. We found that larvae of the scyphozoa Aurelia aurita, Chrysaora hysoscella and Cyanea lamarckii respond to all the compounds mentioned. Trigonelline (N-methylnicotinic acid), a metamorphosis inhibitor found in Hydractinia larvae, is assumed to act by delivering a methyl group for transmethylation processes antagonising metamorphosis induction in Chrysaora hysoscella and Cyanea lamarckii. The three species tested are scyphozoa belonging to the subgroup of semaeostomeae, while Cassiopea spp. belong to the rhizostomeae. The results obtained may contribute to the discussion concerning the evolution of cnidarians and may help to clarify whether the way metamorphosis can be induced in rhizostomeae as a whole is different from that in hydrozoa and those scyphozoa belonging to the subgroup semaeostomeae. Electronic Publication     

Population dynamics of Aurelia aurita (Scyphozoa) from an isolated brackish lake, with particular reference to sexual reproduction

The annual cycle of abundance, growth and sexual reproductionof the scyphomedusa Aurelia aurita was examined over a 12 monthperiod in an isolated, shallow, brackish, man-made body of water:Horsea Lake, England. Strobilation started in December and ephyraewere present through June in varying numbers, suggesting a 7month period of near-continuous recruitment. Horsea Lake hasa dense A.aurita population, with the peak abundance of 24.9m^–3 occurring in mid-May. Medusae (>10 mm) were presentin the water column from March through January. Maximum belldiameter of 105 mm was observed in late September. However,medusa growth was very poor (G ranged between –0.03 and0.07 day^–1 over a 12 month period), and monthly mean belldiameters were typically <50 mm. For most of the year, theabundant A.aurita population was most likely severely food limitedas a result of a numerically and species-poor mesozooplanktoncommunity dominated by the calanoid copepods Acartia margalefiand Acartia tonsa. Nevertheless, the very small A.aurita medusaewere still able to attain sexual maturity and reproduce. Ripefemale medusae carrying fertilized eggs and planula larvae werefirst observed in May and June, although the main period ofplanula larva production was September-December. In November,all females were ripe, the smallest being 19–20 mm belldiameter. At both Horsea Lake and a nearby productive estuary,Southampton Water, planula larva production increased linearlywith wet weight, although compared with the larger A.auritamedusae from Southampton Water, reproductive output at HorseaLake was low. Aurelia aurita in Horsea Lake showed plasticityin its population characteristics in response to environmentalconditions, with both fecundity and size to maturity varyingon a seasonal basis. Medusae appeared to partition the availablefood resources into either somatic growth when food was abundantor reproductive effort when food was scarce.     

Temperature effects on asexual reproduction rates of scyphozoan species from the northwest Mediterranean Sea

In recent decades, many areas worldwide have experienced mass occurrences of jellyfish. To determine how temperature may affect jellyfish populations in the northwest (NW) Mediterranean Sea, we maintained polyps of three scyphozoan species, Aurelia aurita, Rhizostoma pulmo, and Cotylorhiza tuberculata in the laboratory at three temperatures (14, 21, 28°C) to test effects on survival and production of new polyps and ephyrae. Temperature significantly affected survival of all species, with longest survival of A. aurita and R. pulmo at 14°C and of C. tuberculata at 21°C. More polyps were budded by all species at temperatures above 14°C. A. aurita produced the most buds polyp⁻¹ (43.5) and R. pulmo the fewest (8.8). Strobilation occurred only at 14°C for A. aurita and at 21°C for C. tuberculata. For R. pulmo, fewer polyps strobilated and strobilated later at 14°C. These patterns of survival and asexual reproduction were seasonally appropriate for each species in the NW Mediterranean, where A. aurita medusae occur earliest (~April–May) in cool waters, followed by R. pulmo during May–June, and then by C. tuberculata in mid-summer. Comparisons among scyphozoan species suggested that many may be restricted by low temperatures, and that global warming may benefit temperate species, but not tropical or boreal species.     

A New Method for the Separation of Different Types of Nematocysts from Scyphozoa and Investigation of Proteinaceous Toxins Utilizing Laser Catapulting and Subsequent Mass Spectrometry

Jellyfish have an increasing impact on marine ecology. Cnidocysts bearing stinging cells afford, amongst others, prey capture and defence. Several different types of stinging capsules are found in one species and they are supposed to have specific functions, e.g. paralysing prey or adhering to it. Due to these assumed different roles of the capsules, it is suggested that toxins, which are contained in the capsules, differ in composition. Analysis of distinct types of nematocysts requires an appropriate method for the separation of the different types. Mixtures of types of nematocysts were obtained of two species of jellyfish, Aurelia aurita and Cyanea lamarckii, by maceration of the tissue. These mixtures were treated with a method called laser microdissection and pressure catapulting (LMPC). Optimized maceration methods, which were firstly introduced as a method for this purpose, in conjunction with optimized LMPC parameters lead to sufficient amounts of separated capsules of individual types for subsequent mass-spectrometric analyses. In case of A. aurita, the resulting mass spectra had some constituents in common, whereas in the overall pattern, the two distinct nematocyst types differed.     

On some features of embryonic development and metamorphosis of Aurelia aurita (Cnidaria, Scyphozoa)

Aurelia aurita is a cosmopolite species of scyphomedusae. Its anatomy and life cycle are well investigated. This work provides a detailed study on development and structure of A. aurita planula before and during its metamorphosis. Intravital observations and histology study during the settlement and metamorphosis of the planulae demonstrated that the inner manubrium lining of primary polyp (gastroderm) develops from the ectoderm of the planula posterior end. The spatial and temporal dynamics of serotonergic cells from the early embryonic stages until the formation of the primary polyp were studied for the first time. In addition, the distribution of tyrosinated tubulin and neuropeptide RF-amide at different stages of A. aurita development was traced.     

Occurrence of a gelatinous predator (<Emphasis Type="Italic">Cyanea capillata</Emphasis>) may affect the distribution of <Emphasis Type="Italic">Boreogadus saida</Emphasis>, a key Arctic prey fish species

Although the Arctic cod (Boreogadus saida) has a pan-Arctic distribution, little is known about its occurrence in near-shore waters where this species is the principal prey for seabirds, marine mammals and other fish. Published research describes the scyphomedusa Cyanea capillata as an Arctic cod predator, and this paper presents observations from long-term investigations using active hydroacoustics that suggest the Arctic cod avoided C. capillata in two small bays of Cornwallis Island (Canadian High Arctic archipelago). Distribution patterns in echograms suggested that features such as boundary layer fronts restricted jellyfish movements and Arctic cod were often abundant on the side of fronts where C. capillata were absent. Thus, habitat partitioning allowed Arctic cod to share habitat with its predator, albeit exceptions to this sharing occurred when jellyfish abundance was high and Arctic cod were displaced. Thus, if a warmer Arctic triggers an increase in C. capillata abundance, it is possible that small-scale aspects of Arctic cod distribution could be affected. This in turn could have significant ripple effects within the Arctic food web, an additional and previously unrecognized consequence of climate change.