Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4532703 | Continental Shelf Research | 2011 | 6 Pages |
Abstract
The spectral attenuation of solar irradiation was measured during summer in two types of coastal waters in southern Chile, a north Patagonian fjord (Seno ReloncavÃ) and open coast (Valdivia). In order to relate the light availability with the light requirements of upper subtidal seaweeds, the saturating irradiance for photosynthesis (Ek) from P-I curves was measured. In addition the UV risk was assessed. Based on the z1% of PAR, the lower limit of the euphotic zone in the studied systems averaged 21 m (Kd 0.24 mâ1) in Seno Reloncavà and 18 m (Kd 0.27 mâ1) in the coast of Valdivia. Photosynthesis of the studied seaweeds was saturated at markedly lower irradiances than found in their natural depths at the time of the study. Solar radiation penetrating into these depths at both locations largely supports the light requirements for the photosynthesis of subtidal species: 50-160 μmol mâ2 sâ1 for seaweeds from Seno Reloncavà (7 m tidal range) and 20-115 μmol mâ2 sâ1 for Valdivia assemblages (2 m tidal range). Optimal light conditions to saturate photosynthesis (Ek) were present at 10-16 m water depth. The attenuation of solar irradiation did not vary significantly between the fjord and coastal sites of this study. However, the underwater light climates to which seaweeds are exposed in these sites vary significantly because of the stronger influence of tidal range affecting the fjord system as compared with the open coastal site. The patterns of UV-B penetration in these water bodies suggest that seaweeds living in upper littoral zones such as the intertidal and shallow subtidal (<3 m) may be at risk.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Pirjo Huovinen, Iván Gómez,