A study on the light attenuation caused by periphyton in the Burgas Bay, the Black Sea

Abstract

Quantifying PAR attenuation caused by periphyton is a crucial step in setting good management criteria for seagrass habitats protection. To help forward the process of its implementation in the Bulgarian coastal waters we set out to verify experimentally this relationship within several perennial, shallow, sublittoral seagrass meadows. Four types of functional relationships between the dry weight and the PAR quantity have been tested: exponential rise to a maximum, Michaelis-Menten, natural logarithm, negative exponential function (both constrained and unconstrained form). The exponential rise to a maximum proved to be the most appropriate curve for a description of the data under the current experiment. The coefficients obtained: 73.22 (71.02 ÷ 75.48, 95% confidence interval) and 0.8299 (0.7507 ÷ 0.9300, 95% confidence interval) are in the range reported on other experimental studies. The application of a variable for evaluation of the effect of the species composition, especially within the higher loads interval, would improve the curve precision. Nevertheless, it can be useful to assess the seagrasses habitat suitability and the risk of light stress in the Burgas Bay (the Black Sea).