Dpto. Biología. Facultad de Ciencias del Mar y Ambientales, Pol. Río San Pedro s/n. 11510 Puerto Real, Cádiz, Spain Unidad asociada de Oceanografía Interdisciplinar. UCA - Instituto de Ciencias Marinas de Andalucia (ICMAN-CSIC), Pol. Rio San Pedro s/n, 11510 Puerto Real, Cádiz, Spain Department of Ecology and Coastal Management, Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC), Pol. Rio San Pedro s/n, Puerto Real, Cádiz, Spain.
Environ Microbiol Rep. 2012 Jun;4(3):316-25. doi: 10.1111/j.1758-2229.2012.00335.x. Epub 2012 Mar 15.
Macroalgae blooms, a frequent consequence of eutrophication in coastal areas, affect the photosynthetic activity of sediments dominated by microphytobenthos (MPB). Light spectra, steady-state (after 1 h) microprofiles of O2 , gross photosynthesis (Pg ), community respiration in light (RL ) and net community photosynthesis (Pn ) were measured in diatom- and cyanobacteria-dominated communities below increasing layers of Ulva. Photosynthetic photon flux (PPF) decreased exponentially with increasing layers of algae and the light spectrum was increasingly enriched in the green and deprived in blue and red regions. Sediment Pg , Pn and RL decreased as the number of Ulva layers increased; however, 1.6 times higher macroalgal density was necessary to fully inhibit cyanobacteria Pg compared with diatoms, indicating that cyanobacteria were better adapted to this light environment. Long-term (3 weeks) incubations of diatom-dominated sediments below increasing layers of Ulva resulted in a shift in the taxonomic composition of the MPB towards cyanobacteria. Hence, changes in the light climate below macroalgal accumulations can negatively affect the photosynthetic activity of sediments. However, spectral niche differentiation of MPB taxonomic groups and concurrent changes in the MPB community may provide sediments with increased resilience to the detrimental effects of eutrophication.
大型藻类的爆发是沿海富营养化的常见后果，会影响主要由微型藻类（MPB）组成的沉积物的光合作用活性。在越来越多的浒苔层下，我们测量了硅藻和蓝藻占主导地位的群落中，光光谱、稳定态（1 小时后）的 O2 微剖面、总光合作用（Pg ）、光下群落呼吸作用（RL ）和净群落光合作用（Pn ）。随着藻类层数的增加，光合光子通量（PPF）呈指数下降，光谱在绿光区越来越丰富，在蓝、红光区越来越匮乏。随着浒苔层数的增加，沉积物 Pg 、Pn 和 RL 呈下降趋势；然而，与硅藻相比，需要增加 1.6 倍的大型藻类密度才能完全抑制蓝藻 Pg ，这表明蓝藻更适应这种光照环境。在越来越多的浒苔层下，硅藻占主导地位的沉积物进行了为期 3 周的长期培养，导致 MPB 的分类组成向蓝藻转移。因此，大型藻类积聚下光照条件的变化会对沉积物的光合作用活性产生负面影响。然而，MPB 分类群的光谱生态位分化以及 MPB 群落的并发变化可能会增加沉积物对富营养化有害影响的恢复能力。
