R. Santas et al., COMMUNITY RESPONSES TO UV-RADIATION - II - EFFECTS OF SOLAR UVB ON FIELD-GROWN DIATOM ASSEMBLAGES OF THE CARIBBEAN, Marine Biology, 131(1), 1998, pp. 163-171
The effects of ambient solar UV on community productivity and structur
e were assessed during primary succession of benthic diatoms on artifi
cial substrate in a coral reef of the Caribbean. Artificial substrates
, partially enclosed by UV cutoff filters, were placed at a depth of 6
0 cm below surface. During the initial colonization stages, the assemb
lages exposed to the full solar spectrum had a mean productivity 43.4%
lower than the assemblages exposed to PAR + UVA only. Some difference
s in species diversity of assemblages under the different UV treatment
s were also observed. Sensitive species to UVB exposure were Mastogloi
a angulata, M. ovata, M. paradoxa, Nitzschia longissima, Plagiogramma
staurophorum, Rhopalodia musculus, and Surirella ovata. These UVB effe
cts gradually diminished as succession proceeded; 5 to 6 weeks after t
he placement of the substrates in the water, no significant difference
s in productivity were observed between the different treatments, whil
e after 6 weeks of growth, species diversity and evenness were higher,
although not statistically significant, in the UVB-exposed assemblage
s. During the first 2 weeks of growth, the productivity under PAR + UV
A was significantly lower than that under PAR only.