MSGID: 1:317/3 641932ea   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Jellyfish size might influence their nutritional value    
    If jellyfish are 95% water, what makes them such nutritious snacks for so   
   many marine organisms?    
      
     Date:   
         March 20, 2023   
     Source:   
         University of British Columbia   
     Summary:   
         Researchers confirmed what was already known: jellyfish eat   
         bigger prey as they grow, which means they also occupy a higher   
         position in the food web as they grow. They also found that some   
         of the concentrations of 'healthy fats,' increase as jellyfish   
         grow. These changes might be influenced by their diet, and as   
         they feed on bigger prey with higher levels of fatty acids, the   
         jellyfish accumulate more of these fatty acids.   
      
      
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   FULL STORY   
   ==========================================================================   
   Drifting along in ocean currents, jellyfish can be both predator and   
   prey. They eat almost anything they can capture, and follow the typical   
   oceanic pattern of large eats small. Now a recent University of British   
   Columbia study on these gelatinous globs suggests jellyfish may get more   
   nutritious as they get bigger.   
      
      
   ==========================================================================   
   As jellyfish grow, their size changes largely due to the chances of   
   prey encounter, the length and number of tentacles, and their bells   
   (the umbrella- like part of them). As a result, smaller jellyfish eat   
   phytoplankton, microzooplankton, and eggs, while larger jellyfish can   
   eat all of that plus shrimp and even fish. However, jellyfish are also   
   largely preyed upon by animals in and out of the water. Jellyfish are   
   important prey because they are easy to digest due to their high water   
   content, and they are easy to catch.   
      
   "Our study looked more closely to see if there was any information   
   we could draw about nutrition in jellyfish," said Jessica Schaub,   
   lead author and a UBC PhD student at the Institute for the Oceans and   
   Fisheries and the Department of Earth, Oceans and Atmospheric Sciences.   
      
   "This information helps us understand the true value of jellyfish   
   as food. We looked at how the energy that moves through a food web   
   might look as it moves through jellyfish. What they eat, what they are   
   composed of, and how this might affect what eats them." In Heriot Bay,   
   B.C., for example, the moon jelly may often find themselves being eaten   
   by other jellyfish, fish and other invertebrates.   
      
   Schaub, and her team, which includes associate professor Dr. Brian Hunt,   
   who heads the Pelagic Ecosystem Lab at the Institute for the Oceans   
   and Fisheries, took a look at how jellyfish size, diet and nutritional   
   quality all mesh together. Nutritional quality can reflect an organism's   
   life history -- the composition of a jellyfish can change in response   
   to individual changes in diet and physiological changes.   
      
   The team, over two one-day periods in July and September 2019, collected   
   150 moon jellyfish and measured their size. After drying them, they   
   measured the jellyfish for specific compositional elements.   
      
   Schaub described what they discovered.   
      
   "First, we confirmed what was already known: jellyfish eat bigger   
   prey as they grow, which means they also occupy a higher position in   
   the food web as they grow," she said. "We also found that some of the   
   concentrations of 'healthy fats,' increase as jellyfish grow. We found   
   some evidence that these changes might be influenced by their diet,   
   and as they feed on bigger prey with higher levels of fatty acids, the   
   jellyfish accumulate more of these fatty acids."  "This means bigger   
   jellyfish might be considered more nutritious," said Schaub.   
      
   The study found size-trends which emphasize just how important it   
   is to consider jellyfish size when we are talking about marine food   
   webs. Including these creatures will not only help their representation   
   in food web models, but can also inform other studies.   
      
   Looking towards the future, Schaub described what may come next.   
      
   "Our recommendation for future studies on jellyfish predators is to   
   consider size more thoroughly. Feeding on a young, small jellyfish is   
   different than feeding on a larger and older jellyfish."   
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # Sea_Life # Marine_Biology # Fisheries #   
                   Pests_and_Parasites   
             o Earth_&_Climate   
                   # Ecology # Water # Environmental_Awareness # Ecosystems   
       * RELATED_TERMS   
             o Jellyfish o Omega-3_fatty_acid o Pitcher_plant o Snake o   
             Essential_nutrient o Algal_bloom o Amino_acid o Trophic_level   
      
   ==========================================================================   
   Story Source: Materials provided by University_of_British_Columbia. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Jessica Schaub, Anna K. McLaskey, Ian Forster, Brian P. V. Hunt.   
      
         Size‐based changes in trophic ecology and nutritional quality   
         of moon jellyfish ( Aurelia labiata ). Ecosphere, 2023; 14 (3)   
         DOI: 10.1002/ ecs2.4430   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230320143818.htm   
      
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