Modelling the sustainability of overwintering Mnemiopsis leidyi populations in the North Sea

  • Ian Gardiner

Student thesis: Master's Thesis


Invasive species are widely accepted as one of the leading threats to global biodiversity. The invasive ctenophore Mnemiopsis leidyi gained notoriety in the late 1980s when its explosive population growth in the Black Sea - following accidental introduction via ballast water - coincided with a drastic reduction in the stock of the anchovy Engraulis encrasicolus in the region. M. leidyi has since been found in the coastal waters of many European countries and is a major cause for concern in these areas. In February 2009, M. leidyi was recorded at several offshore locations in the North Sea raising concern among researchers regarding the widely held belief that the winter conditions of the North Sea proper were unsuitable for the survival of the ctenophore. The General Estuarine-Ocean Transport Model (GETM) coupled with the European Regional Seas Ecosystem Model-Biogeochemical Flux Model (ERSEM-BFM) and a Lagrangian particle tracking individual behaviour model (GITM) are used to examine the origin and sustainability of these overwintering M. leidyi individuals. The main results of this research are: (i) the model suggests it is possible there exists a UK population of M. leidyi somewhere along the English coast that has thus far gone undetected; (ii) M. leidyi can survive in the North Sea proper the entire winter until the summer months of July and August when conditions are most favourable for reproduction; (iii) under current climatic conditions the model finds the reproductive capability of M. leidyi in the North Sea proper to be minimal due to the relatively low summer temperatures and the consequent high (juvenile) mortality. Theses results are presented with the caveat that there remains substantial uncertainty regarding the model parameterisation which can only be improved with further research on the species. For this reason it is advisable that more effort is dedicated to investigating the factors influencing the rate of transfer between life stages and the mortality rates of M. leidyi at lower temperatures.
Date of Award1 Apr 2016
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsEPSRC (Engineering and Physical Sciences Research Council)
SupervisorLouise Kelly (Supervisor) & Douglas Speirs (Supervisor)

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