Resolving the role of jellyfish in marine food webs

Lamb, Philip (2018) Resolving the role of jellyfish in marine food webs. Doctoral thesis, University of East Anglia.

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Abstract

Jellyfish populations in the Irish Sea have been increasing. This has caused a variety of economic problems, such as the destruction of aquaculture installations, and new opportunities, such as the establishment of a jellyfish fishery. However, interactions between jellyfish and other biota in the ecosystem is poorly characterised and ecological consequences of an increasing jellyfish population remains unknown.
Molecular gut content analysis methodologies were developed to address this data gap. Cnidarian specific primers were developed and showed using more than 2500 stomachs that, during February and March, moon and mauve-stinger jellyfish were consumed by common fish species including herring, whiting, and lesser-spotted dogfish. Revisiting the ecosystem in October with 375 additional samples, the primers indicated jellyfish predation varied temporally: small jellyfish were still targeted by mackerel, however moon jellyfish adults were not preyed upon. To understand the context in which jellyfish consumption occurred a high throughput sequencing (HTS) approach using two universal primers was developed. A meta-analysis of HTS studies suggested results contained a quantitative signal, and the methodology could be used to move beyond a presence/absence approach. Using 188 samples from nine fish species, it was shown that jellyfish were consumed as part of a generalised diet during summer months. Finally, the approaches used to model jellyfish in the ecosystem model Ecopath with Ecosim (EwE) were reviewed. Jellyfish were included more frequently over time, however approaches remained relatively crude in the absence of high quality data in many ecosystems. Together, these approaches have gone some way towards addressing the data gap: jellyfish interactions with other biota have been recorded, and new approaches for studying these interactions have been developed. This has established a baseline for novel research opportunities such as mechanistic modelling of jellyfish, exploration of quantitative HTS approaches, and the generation of dietary time-series data to be conducted.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Megan Ruddock
Date Deposited:	19 Feb 2019 14:28
Last Modified:	27 Sep 2019 00:45
URI:	https://ueaeprints.uea.ac.uk/id/eprint/69971
DOI:

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