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Title: The ecology and dynamics of the brackish water prawn, Palaemonetes varians (Leach) and its interrelationships with the common goby, Pomatoschistus microps (Kroyer) in artificial coastal lagoons of the Ribble Estuary, Lancashire.
Author: Hindley, John D. L.
ISNI:       0000 0001 3578 8422
Awarding Body: University of Lancaster
Current Institution: Lancaster University
Date of Award: 2001
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The Brackish Water Prawn Palaemonetes varians (Leach) is common throughout coastal waters of the UK and Western Europe. Its preferred habitat is within sheltered waters of lagoons, though it is not a major constituent of estuarine tidal flux. Bottle traps were used to assess the seasonal 'activity' and habitat density of P. varians in artificial coastal lagoons on saltmarshes and claimed marshland habitats. Additionally, the potential diet resources available to P. varians were investigated between sites. The data revealed that relict landward lagoons and saltmarsh borrow pits were successful breeding areas for P. varians, the latter acting as a major replenishing resource in the estuary. Differences in breeding period and growth rate, assessed using maturation, zoeal and enclosure data were found to be attributed to environmental temperature rather than habitat food resources. P. varians was found to adapt to varying prey resources showing an ontogenetic shift in prey size with increasing body size, which was correlated with chelal grab width. The chelal morphology of P. varians in relation to feeding behaviour was described using Scanning Electron Microscopy (SEM). Structural and setal variation accounted for 'passive' and 'active' feeding behaviour portrayed by P. varians. Within the sites studied, the Common Goby, Pomatoschistus microps (Kreyer) was also a cohabitant with P. varians. Bottle trap data demonstrated that whilst the seasonal activity of P. microps in claimed marsh lagoons was linked to temperature, within the intertidal borrow pits an autumnal inmigration pattern was identified. The autumnal peak of P. microps was shown to have a profound effect on the abundance of P. varians. Different seasonal and ontogenetic diet trends were established for P. microps, via gut and morphological analyses and they were used to investigate the extent to which P. varians was utilised as a prey resource. Furthermore, comparisons were made between the Grass 'Shrimp', P. pugio (Holthuis) and MUmmichog, Fundulus heteroclitus L. These species occupy a comparative habit and are important species in the ecological structuring of American saltmarsh ecosystems. Digital video and mesocosms were used as further tools to investigate the interrelationships and predation of P. varians by P. microps. It is shown that whilst the predation of P. varians does occur in microcosms, the predation efficiency of P. microps was limited by tail-flip escape swimming (TFES) of P. varians.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available