Who's Got Jellies in their Gut?

Gelatinous zooplankton, loosely termed as jellyfish, can be found throughout world’s oceans, known to cause large blooms. This group includes scyphozoan jellyfish, siphonophores, ctenophores, salps, pyrosomes, and appendicularians [1]. 

If we were asked who dines on these jellies, we might reserve the term ‘belly-full-of jelly’ to charismatic sea turtles (Dermochelys coriacea, Chelonia mydas) and the ocean sunfish (Mola mola). And it's indeed fitting since an adult leatherback turtle, for instance, ingests an average of 330-kg jellyfish wet mass per day or 73% of its body mass [1]. 

With the rise of new technologies in recent years, however, this exclusivity is no longer true: It turns out that not only such massive marine predators get a chunk of their diet from jellyfish. There’s a whole lot on the table, from birds to fishes to worms, joining the feast [1].

New approaches to study the diet of marine animals such as stable isotope analyses or SIA (getting animal tissues to estimate trophic level), animal-borne cameras, remotely operated vehicles or ROVs, and DNA metabarcoding support the finding that a diverse range of marine predators feed on jellies, not incidentally but targeted [1].  

SIA revealed that jellyfish forms a substantial part of the diet of bony fishes Chloroscombrus chrysurus, Thunnus thynnus, Euthynnus alletteratus, Tetrapterus belone, Xiphias gladius and the green sea turtle Chelonia mydas. 

Animal-borne cameras revealed 42.2% of prey capture for some species of penguins, consuming scyphozoans, salps and ctenophores [1]. 

Metabarcoding showed that jellies make up 20% of food DNA sequences of the two species of albatross, ahead of crustaceans in terms of importance. Meanwhile, next-generation sequencing showed that the endangered European eel Anguilla anguilla has got gelatinous zooplankton in its diet. Seen through powerful ROVs, deep-sea octopus (Haliphron atlanticus) and benthic animals, like echinoderms, crabs, shrimps, amphipods, sea anemones, and worms join the slew of jellyfish predators [1].

Hays et al. 2018 Figure 2A, showing a diverse group of predators worldwide feeding on jellyfish.

Overwhelming evidence of widespread jellyfish consumption throughout the world’s oceans means that jellyfish cannot be simply considered a bycatch, but targeted and opportunistically consumed by many marine predators. However, it's important to note that this shift may be influenced by changing ocean conditions [1]. 

Also, knowing that a growing number of marine life now relies on jellyfish for nutrition signifies their susceptibility to harm, or even death, for mistaking plastic wastes for food [1]. 

These findings are important given that jellyfish holds a huge fraction of the pelagic biomass and have recently increased their abundance worldwide [3]. The study also challenges the common notion that undermines the energetic gain from jellyfish consumption, thus the need to better understand its dietary value [1].

To know more about jellyfishes and other gelatinous zooplankton, visit SeaLifeBase. 

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[1] Hays, G. C., Doyle, T. K., & Houghton, J. D. (2018). A Paradigm Shift in the Trophic Importance of Jellyfish?. Trends in Ecology & Evolution 33(11):874-884. Retrieved from https://bit.ly/2DCvaY7

 [2] Lewis, A. (2011, January 5). Leatherback turtle feeding. YouTube. Retrieved from https://bit.ly/1vo1QO8

Untangling the human-jellyfish connection

Last month's mini-symposium Q-quatics 2019: Road Ahead has been productive, providing a means for Q-quatics to communicate possibilities to execute its fisheries and oceans mandate through collaborations with the global scientific community.

Many participants took an interest in the talk of Lucas Brotz, jellyfish expert and Q-Quatics Cnidaria Scientist, as he shared the ever growing, inevitable relationship of humans and jellyfish today.

Based on a rigorous study Brotz led, jellyfish populations, indeed, have been increasing since 1950: out of the 45 large marine ecosystems (LMEs) analyzed, 62% showed increasing trends [1]. This brought with it changes that we are only now seeing—more reports of children dying from box jellyfish stings [4], swarms of jellyfish regularly interrupting fishing activities [2], jellyfish responsible for massive power failure in Luzon [3], and jellyfish turning into snacks [4]. While the demand for jellyfish for food has increased, huge economic losses are incurred by many related industries [4].

Fig. 1. Map of population trends of native and invasive species of jellyfish by large marine ecosystem (LME) (Source: Brotz et al. 2012)

A regular day for fishermen in Japan, clearing the infestations of Nomura (Copyright: Shin-ichi Uye, Hiroshima University)

Counter-measures to control jellyfish populations have been done but with mixed results. A more apparent move, to exploit jellyfish as food, was seen as an opportunity to deter this global rise. However, as Brotz pointed out, eating our way out isn't the likely solution. Rather, adaptation may be our best approach [4]. 

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Sources:
[1] Brotz, L., Cheung, W. W., Kleisner, K., Pakhomov, E., & Pauly, D. (2012). Increasing jellyfish populations: trends in large marine ecosystems. In Jellyfish Blooms IV (pp. 3-20). Springer, Dordrecht. Retrieved from https://bit.ly/2Ea4tvi

[2] Vince, G. (2012, April 5). Jellyfish blooms creating oceans of slime. BBC. Retrieved from https://bbc.in/2hLG1Cc

[3] BBC (1999, December 11). Jellyfish blamed for Philippines blackout. BBC News.  Retrieved from https://bbc.in/2LHCIv2

[4] Brotz, L. (2019, January 31). Jellyfish and humans - the big picture. Q-quatics 2019: road ahead symposium. 

Collaborator of the Month: Lucas Brotz

Photo courtesy of Lucas Brotz

Lucas Brotz holds a Bachelor’s degree in Astrophysics and a Master’s degree in Oceanography. Currently, he is undertaking his doctorate in Zoology at the University of British Columbia’s Institute for the Oceans and Fisheries under the guidance of the esteemed Dr. Daniel Pauly. He is also working with the Sea Around Us.

His research focuses mainly on changing jellyfish populations and jellyfish fisheries, as well as the economic impacts of jellyfish blooms. A study that he published in 2012 together with UBC scientists was the first attempt to identify changes in global jellyfish abundance. Analysis of available data from 1950 to the present confirmed a remarkable rise in their populations. This was evident in 28 of the world’s Large Marine Ecosystems, or 62 percent of the regions analyzed.  

Consequently, this study has immense implications for humans and ecosystems. Negative impacts of this global phenomenon are felt on human activities like fishing, aquaculture, tourism, power generation, and desalination, among others. Aside from exploiting jellyfish as a food source, people may have to resort to creative ways to reduce economic loss. No single factor is responsible for increasing jellyfish blooms, but mounting evidence suggests that pollution, aquaculture, fishing, shipping, global warming, and coastal development are likely to contribute to this observed rise. UBC scientists urge that subsequent studies on jellyfish populations and awareness are vital to make sure we still have fishes, and not just jellyfishes, on our plates.

Lucas Brotz makes use of SeaLifeBase for jellyfish taxonomy as well as FishBase, since he is also studying the dynamics between jellyfish populations and fisheries. He has contributed data on taxonomic updates of jellyfish, photographs of jellyfish, and scientific papers on jellyfish populations as well as the results of his MSc Thesis.

Cheers to more years of collaborating with you!

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The University of British Columbia Fisheries Centre . http://www.fisheries.ubc.ca/students/lucas-brotz [Accessed 6/29/2015]

The University of British Columbia. http://news.ubc.ca/2012/04/18/jellyfish-on-the-rise-ubc-study/  [Accessed 6/29/2015]

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Ocean Giants: Nomura's jellyfish

If the longest medusozoid is the lion's mane jellyfish, the heaviest would be Nomura's jellyfish. Scientifically known as Nemopilema nomurai, it is found endemic to the East Asian Marginal Seas - Bohai Sea, Yellow Sea and East China Sea [1]. The largest recorded species measured 2 m in bell diameter and weighed 200 kg [2].

Photo by Choi, Jong-Kwan taken in Korea.

Majestic as this species can be, fishers have found them troublesome. Since the early 2000s, jellyfish bloom has threatened the fisheries of Japan; instead of fishes, nets were full of this jellyfish. Studies conducted to determine the cause of the increasing frequency of jellyfish blooms in Japan revealed global warming and overfishing as the main factors [1, 3]. 

1. Global warming: It appears that podocysts are carried out by the Tsushima Current from the Yellow Sea to the Sea of Japan. Exposure to higher temperatures triggers their development into medusa form. This explains why the bloom occurs only in Japan, not in China nor in Korea. 
2. Overfishing: Note that both fish and jellyfish prey on zooplankton. Thus, excess fishing is advantageous to jellyfish because of decreased competition. Since there are fewer fishes, they can easily dominate the area where food is readily available.

Photo by Shin-ichi Uye, Hiroshima University, posted on BBC.

To know more about the biology of Nomura's jellyfish, visit SeaLifeBase.

If you have other information on them, which you wish to include in our information system, please e-mail us at sealifebase@fin.ph or join us as a collaborator.

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[1] Uye, S (2008) Blooms of the giant jellyfish Nemopilema nomurai: a threat to the fisheries sustainability of the East Asian Marginal Seas. Plankton Benthos Res 3 (Suppl.):125-131.
[2] McClain, CR, et al (2015) Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ 2:e715. Accessed from https://peerj.com/articles/715/
[3] Kawahara, M, Ohtsu, K, Uye, S (2013) Bloom or non-bloom in the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae): roles of dormant podocysts. J. Plankton Res. 35(1):213-217.

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Ocean Giants: Lion’s Mane Jellyfish

The longest known species of jellyfish is the common lion's mane Cyanea capillata found in the northern waters, from the Arctic to the north Atlantic and Pacific.

Lion's mane jellyfish moving sideways (photograph by Herb Segars from www.arkive.org).

The maximum bell diameter and tentacle length were based on an illustrated catalog of a medusae found off the east coast of the United States by Agassiz (1965) where he wrote,

"I measured myself a specimen at Nahant, the disk of which had attained a diameter of seven and a half feet, the tentacles extending to a length of more than one hundred and twenty feet." 

But based on a molecular study conducted by Dawson (2005), the medusae recorded by Agassiz was very much distinct from Cyanea capillata and may thus be an undescribed Cyanea sp. [1, 2] Although no other available literature can provide the maximum length it can attain, the proposed argument by Dawson gives speculations that there may be an unidentified jellyfish waiting to be discovered.

To know more about the lion's mane jellyfish, visit SeaLifeBase.

If you have other information on them, you can e-mail us at sealifebase@fin.ph or come be 

a collaborator.

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[1] McClain CR, Balk MA, Benfield MC, Branch TA, Chen C, Cosgrove J, Dove ADM, Gaskins LC, Helm RR, Hochberg FG, Lee FB, Marshall A, McMurray SE, Schanche C, Stone SN, Thaler AD. 2015. Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ 3:e715.

[2] Dawson MN. 2005. Cyanea capillata is not a cosmopolitan jellyfish: morphological and molecular evidence for C. annaskala and C. rosea (Scyphozoa : Semaeostomeae : Cyaneidae) in south-eastern Australia. Invertebrate Systematics 19:361-370.

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Wind sailors of the sea

Have you ever walked along the beach and encountered a fleet of bluish mussels on the shore? They are in fact not mussels but hydrozoans, famously known as by-the-wind sailors.  

Although physically similar with the Portuguese man o' war, this is not a jellyfish. Scientifically called Velella velella, it is the only known species under the genus of free-floating hydrozoans. It is found worldwide in both tropical and temperate waters. With a deep-blue rectangular float and an upright triangular sail, it looks like a miniature sailboat, on which its name was coined. 

This colonial species is made up of clustered polyps/zooids categorized into two types: gastrozooids and gonozooids. Gastrozooids function for plankton feeding using its tentacles (see photo above), while gonozooids have a reproductive function, that is, to constantly release medusa to the open waters. Having no means of locomotion, they are at the mercy of the wind to move around the seas and are thus, prone to mass-strandings on coastal beaches.

To know more about the by-the-wind sailors, visit SeaLifeBase.

If you have other information on them, you can e-mail us at sealifebase@fin.ph or come be a collaborator.

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Source: Monterey Bay Aquarium (MBARI). See page link here.Photos by Christian Coudre.
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Philippine fisheries and Daniel Pauly in Oceana Magazine

Oceana recently released their Summer 2012 magazine.

The Small Sanctuary Approach

Read the article at pages 8- 11.

Good coastal fisheries stewardship, combined with national policies on quotas, habitat and bycatch, can alleviate poverty.

The status of the marine protected areas, condition of the coastal communities, and municipal fisheries of the Philippines are featured. Find out how commercial fisheries are classified as artisanal fishing in the Philippines.

Ask Dr. Pauly: Are the Oceans Jellifying?

Ask Dr. Pauly at page 13.

People notice jellyfish more these days – or is it the jellyfish that notice more people? In any case, more people are getting stung – a rash of rashes as it were.

Daniel Pauly once again talks about jellyfish and the possible causes of the outbreaks. Is it really because of global warming?

Visit Oceana to know more or click here to read the rest of the magazine.

Posted by:

Lealde Pacres-Urriquia

Research Assistant

The SeaLifeBase Project

Daniel Pauly in Synergy Online

SeaLifeBase Project Principal Investigator Daniel Pauly is cited in the July 2012 issue of Synergy Online, journal of the Faculty of Science, University of British Columbia (UBC).

In the article Jellyfish Rising, Pauly mentioned that the scope of the jellyfish populations study can further be extended into a global scale by combining published scientific data with other unpublished data and observations, which can then result to the "best available scientific estimate" of the jellyfish blooms.

Visit Synergy to read the rest of the article.

Posted by:

Lealde Pacres-Urriquia

Research Assistant

The SeaLifeBase Project