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Christopher Lynam
Jellyfish Ecology
e-mail Chris
Gatty Marine Laboratory
Telephone +44 (0) 1334 463465
Fax +44 (0) 1334 463443
History
My career in Biology began in 2001 with the Univeristy of St. Andrews MRes (conversion course for mathematicians physical and molecular scientists) in Evolutionary and Environmental Biology. Prior to that I worked for a year as a Technical Officer at the United Kingdom Atomic Energy Authority (UKAEA). I gained my undergraduate degree, BSc(Hons) in Physics, from the University of Manchester in 2000.
Research
I am studying for a PhD currently entitled Ecological and Acoustic Investigations of Jellyfish. Having a NERC quota-studentship has allowed me to explore many avenues of interest and I have focused on three main problems:
The simple problem with jellyfish is that they are gelatinous. The jelly-like bodies of jellyfish make them unsuitable for trawling with standard plankton nets since the jellyfish are effectively sieved by the mesh of the net which turns their delicate bodies to goo leading to problems in counting the number caught and estimating the volume of water sampled. In addition to this, jellyfish often aggregate in swarms and large catches may overload and burst nets. So, we are developing new acoustic techniques to estimate the abundance of jellyfish that do not rely on quantitative catches by netting. We have applied these techniques in the Namibian benguela and are attempting to use the acoustic data collected to estimate the abundance of jellyfish there.
The rate of development of young medusoids, and also the timing of their release from the sessile polyp stage, is dependent on the level of food availability, light, salinity and temperature in the environment. There is growing awareness that large-scale climatic variation can lead to changes in the marine environment and influence the abundance and composition of the zooplankton community, and that this, in turn, can have major consequences for fisheries.
To see if I could relate climatic change to changes in the abundance of jellyfish I have analysed a time-series of jellyfish abundance in the North Sea and compared this to an index of the North Atlantic Oscillation (NAO), which allows us to quantify environmentally-driven change in the ecosystem. I found a significant link between jellyfish abundance and the NAO index such that during low NAO years a great abundance of jellyfish were found in the North Sea while during high NAO years many fewer jellyfish were found (see the project page Jellyfish and Climate or my poster presentation at the UK GLOBEC meeting 26 February 2004).
Jellyfish medusae are known to prey heavily upon the zooplankton and, when available, fish larvae may be a dominant food source (Purcell and Arai 2001; Schneider and Behrends 1998). Jellyfish may be detrimental to the survival of the young herring, particularly in the first few months after hatching. Medusae of Aurelia aurita have been seen to have a devastating impact on a population of Atlantic herring (Clupea harengus) yolk-sac larvae in the Baltic Sea (Möller 1984) and the hydrozoan medusa Aequorea victoria has been shown to prey on Pacific herring in British Columbia (Purcell and Grover 1990). Möller (1984) found that even a small (6 mm) A. aurita medusoid was able to catch herring larvae, and as many as 68 larvae were present within the stomach of a single medusa only 42 mm in bell diameter.
Competition between jellyfish and adult fish is also possible; dietary similarities and overlaps between medusae and Pacific herring (Clupea pallasi) of 73% and 50% have been found for Aurelia labiata and Cyanea capillata respectively (Purcell and Sturdevant 2001).
We have found that the abundance of Aurelia aurita medusae in the North Sea is negatively correlated with the recruitment of 0-group herring and that the impact of these medusae may be mediated by the environment (as quantified by the NAO, see section 2 above) and the relative abundance of Cyanea capillata. I have a paper in review discussing the possible interactions between jellyfish, herring and the environment and have presented my results at the recent ICES Symposium in Bergen entitled The Influence of Climate Change on North Atlantic Fish Stocks (my presentation is available online in both PowerPoint and pdf formats).
Some of my activities
I am an anonymous referee for the journal Limnology and Oceanography
and a member of the American Society of Limnology and Oceanography (ASLO)
I re-designed this website
Teaching
Here at St Andrews I have been involved in teaching on a number of courses including:
Statistical Modelling (M.Res.)
Modelling Ecological Dynamics (M.Res.)
Conservation Biology (M.Res.)
Statistics for Biologists (2nd year)
Quantitative Methods in Biology (1st year)
Statistics in Practice (1st year)
Background picture: a plankton bloom and cold core eddies in the gulf stream courtesy of NASA and the Lunar and Planetary Institute |
