A study of the bioerosion of coastal limestones: a photogrammetric approach

Iams, William James (1977) A study of the bioerosion of coastal limestones: a photogrammetric approach. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

The present study investigates the importance of bio-erosion in the destruction of coastal limestones of the tropical island of Barbados. A stereophotogrammetric system capable of obtaining yearly photographs of the rock surface and of providing quantitative data on rock surface data points from which erosional values can be obtained is described. Results of photogrammetric analysis of five study localities show a range of erosion rates (for intertidal and supratidal localities) which vary from 1.2 mm./year to 2.4 mm./year. Following establishment of erosion rates for the localities studied, calculations have been carried out to determine the erosional capabilities of the epilithophagic organisms present on the rock surfaces. These calculations show that in no case do epilithophagic organisms account for more than 40 per cent of the total erosion. Other factors which may account for the remaining erosion include physical and chemical weathering as well as non-epilithophagic biological erosion. The author suggests that of the latter category the erosional effects of boring microphytes (chasmolithic and endolithic algae and fungi) are extremely important in explaining the non-epilithophagic erosion. These microphytes act directly on the substrate by biochemical boring activity and indirectly by attracting the epilithophagic organisms which rasp the rock to gain nourishment provided by the thalli of the microphytes.

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