Marine Research Findings of the VECTORS Project

This website provides access to the research results of the VECTORS project, which can be used to support marine management decisions, policies and governance as well as future research and investment. VECTORS was a large scale project that brought together more than 200 expert researchers from 16 different countries. It examined the significant changes taking place in European seas, their causes, and the impacts they will have on society.

Individual growth model for jellyfish Pelagia noctiluca based on laboratory experiments and field measures

In the last decades, there have been increasing reports about extensive jellyfish blooms around the world. At the same time many fish top predators’ populations are decreasing due to fishery, habitat degradation, pollution and global changes. These two phenomena could indicate that a shift in the marine ecosystems is underway, the jellyfish slowly but steadily occupying the ecological niches left empty by the disappearing fish populations. Thus, it is of great importance to understand the potential impact of jellyfish population on the food webs of marine ecosystems.

Pelagia noctiluca is a painfully stinging holopelagic jellyfish, occasionally causing massive outbreaks. The outbreaks pose a threat to various human activities, such as tourism, navigation and fishery, while affecting the natural habitats by consuming their resources and disrupting the cycling of energy and matter.

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Individual based growth model for jellyfish Pelagia noctiluca in different life stages.

Based on laboratory data collected in this project, we found mathematical functions modelling P. noctiluca clearance and respiration rates in the ephyra and juvenile stage as functions of water temperature, food concentration and body size. We also identified allometric relationships between diameter and dry weight separately for ephyras, juveniles and adults. The model for the ephyra and juvenile stage was built and validated against growth observed in laboratory. Population data sampled in the Strait of Messina were used to calibrate the parameters of the clearance rate function for the adult stage of P. noctiluca. Together, they form a growth model in different life stages of P. noctiluca.

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Pelagia noctiluca is a voracious feeder.

The model built and validated on experimental data of ephyra and juveniles was forced with mesozooplankton concentrations measured in the Strait of Messina. The field concentrations proved to be far to small to permit jellyfish to grow according to our model. Thus we estimated that a much higher food concentration is effectively exploited by the organism in the natural environment, possibly coming from all size components of plankton (microphytoplankton, microzooplankton, mesozooplankton), as well as from variable amount of ichtyoplankton (fish eggs, larvae). Our findings were in accordance to experimental results on P. noctiluca diet found in this same project by Milisenda et al1.

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Pelagia noctiluca might be negatively affected by global warming.

According to our results, the respiration rate of P. noctiluca is proportional to seawater temperature. Thus, every increase in seawater temperature could cause a higher respiration rate, affecting the whole metabolic balance. We simulated the growth of P. noctiluca in a A3 IPCC scenario (increase of 3.4°C at 2090-2099 relative to 1980-1999) and found that while the growth rate is slowed down, much probably such temperature increase could not significantly alter P. noctiluca populations in the Strait of Messina.

Relevance for Policy:
  • Alien Invasive Species Directive
  • EU Biodiversity Strategy
  • Marine Strategy Framework Directive
  • Water Framework Directive

References

Lead Author:

Cosimo Solidoro and Vinko Bandelj & Vinko Bandelj
(vbandenospamlj@ingos.it)
National Institute of Oceanography and Experimental Geophysics (OGS)
Date of research: October 2014

Related articles:

Vital rates of fish larvae 

Extreme ecological events and jellyfish outbreaks

Functional responses of herring and sprat to prey 

Impact of jellyfish on fisheries and tourism 

Population dynamics of sprat in the Baltic Sea 

The drivers of a common sole population 

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This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 266445
© Vectors 2015. Coordinated by Plymouth Marine Laboratory.