The Biology of Lembos websteri and Corophium bonnellii (Crustacea: Amphipoda) in Relation to Turbulence and Turbidity

Shillaker, Richard Oliver (1977) The Biology of Lembos websteri and Corophium bonnellii (Crustacea: Amphipoda) in Relation to Turbulence and Turbidity. PhD thesis, University of Glasgow.

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Abstract

The biology of two members of the Laminaria holdfast community, the amphipods Lembos websteri and Corophium bonnellii. was investigated. Information was derived from field sampling and laboratory based observations and experiments. The experiments concentrated on the effects (1) of water movement, and (2) of settling and suspended inorganic particles. Both species build tubes out of sediment that accumulates in the holdfasts. Tubes constructed from long strands of fine filamentous algae are also occupied. Tube building relies heavily on the activity of the first two pairs of pereopods. Most Corophium occupied tubes which were away from or only loosely attached to the haptera, whilst most Lembos occupied tubes which were more firmly attached to the haptera. Even when attached to the haptera the tubes of both species are easily dislodged. The juxtaposition of Laminaria holdfasts and unstable sand, at Fintray Bay, results in sand accumulating in the holdfasts. Corophium, along with other animals, utilizes this sand to form a dense mat of tubes, which greatly alters the micro-environment of the holdfast. With the exception of male Lembos, both species rarely leave their tubes. In the absence of females, male Lembos vacate their tubes more frequently at night than during the day. However, the extent to which such a clear cut difference occurs in the field is uncertain. The hypothesis that male Lembos leave their tubes to seek out and enter the tubes of mature females is confirmed with limited data. Lembos and Corophium ingest a wide variety of food items, with suspended organic detritus being of major importance. Phytoplankton must also be of considerable importance to Corophium. due to its highly efficient fine particle filtering apparatus. In contrast, Lembos is better adapted for filtering larger particles. The more frequent occurrence of Lembos at exposed, rather than sheltered, localities may be due, in part, to larger food particles being more abundant in more turbulent waters. In still water, where suspended particulate detritus is absent, Lembos is more liable than Corophium. to purposely reingest its own faecal pellets and to eat its own tube. Limited diurnal variation in an index of gut fullness is a feature of both species. This variation may be due, in part, to tidal variation in the suspended solid load around the Laminaria holdfasts. Female Corophium can remove embryos from their marsupia and subsequently eat them. Young Lembos remain longer in their mother's marsupium and tube, than young Corophium. The more lengthy association of recently hatched Lembos with their mother may be related to the occupation of wave exposed localities. The behaviour of young in their mother's brood pouch and tube is described. Of particular ethological interest is the avoidance of males by young Lembos. The survival of Corophium and possibly also of Lembos is independent, over short periods, of natural levels of inorganic turbidity. Contamination of their marsupia is probably one means by which inorganic turbidity can act as a deleterious factor. Inorganic and organic turbidity have only a limited influence on pleopod activity. Corophium. due to its stronger pleopod current, is better able than Lembos to withstand clay sedimentation. High levels of turbulence are more inhibitory to the normal activity of Corophium than Lembos.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Biological oceanography
Date of Award: 1977
Depositing User: Enlighten Team
Unique ID: glathesis:1977-78749
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 14:56
Last Modified: 30 Jan 2020 14:56
URI: http://theses.gla.ac.uk/id/eprint/78749

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