Some effects of high temperatures on the perch Perca fluviatilis (Linnaeus) and their importance in influencing its distribution

Weatherley, Alan H (1961) Some effects of high temperatures on the perch Perca fluviatilis (Linnaeus) and their importance in influencing its distribution. PhD thesis, University of Glasgow.

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The upper lethal temperature of the common perch Perch fluviatilis (L.) was determined experimentally in relation to acclimatization temperature. The information thus obtained was combined with knowledge of the distribution of the species in nature, to determine the extent to which high temperature limits its proximity to the equator. This analysis was aided by knowledge of the distribution of the very closely related yellow perch Perca flavescens (Mitchill) of North America. It was concluded that the distribution of both species is controlled by two principal factors. The first of these is their inability to live in streams, or sections thereof, with steep gradients. The second, high water temperature in midsummer, appears to exercise its effects in at least two extensive regions of the world. However, it appears almost certain that perch can live in waters in which midsummer temperatures may be only a degree or so below their upper lethal temperature. The conservative behaviour of perch, which inhibits free dispersal of these species, probably plays an important secondary role in influencing the distribution pattern. It is believed, then, that the more or less direct effects of temperature can control perch distribution, sometimes over a vide front, and that the mechanisms by which heat brings about its disabling or lethal effects are therefore of considerable importance for these two species. The major part of this thesis describes an investigation of some aspects of these mechanisms. When specimens of P. fluviatilis were examined histologically it was found that exposure to (even moderately) high temperatures led to lymphocyte depletions in the head kidney and to cellular atrophy of the interrenal tissue. Higher levels of thermal exposure led, in addition, to more profound changes, so that when perch were exposed to temperatures of 28-50

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: C M Youge
Keywords: Physiology, Aquatic sciences
Date of Award: 1961
Depositing User: Enlighten Team
Unique ID: glathesis:1961-73493
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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