Name: Caroline Quenupe Campos
Type: MSc dissertation
Publication date: 30/05/2018
Advisor:
Name |
Role |
|---|---|
| Camilla Rozindo Dias Milanez | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Camilla Rozindo Dias Milanez | Advisor * |
| Geisamanda Pedrini Brandão Athayde | External Alternate * |
| Geraldo Rogério Faustini Cuzzuol | Internal Alternate * |
| Gloria Maria de Farias Viégas Aquije | External Examiner * |
| Silvia Tamie Matsumoto | Internal Examiner * |
Summary: ABSTRACT
The mangroves are coastal ecosystems frequently exposed to the pollution
by heavy metals, which accumulate in sediments at high level content. It is
known that the bioavailability and toxicity by such metals in the sediment is
modified by the salinity, pH, soil organic matter, and other factors. According
to the Intergovernmental Panel on Climate Change (IPCC), there is a
forecasting of decreasing in precipitation with a consequent increasing of the
salinity in tropical regions. Despite of the relevance of this theme, few is
known about the morphological, anatomical, physiological and biochemical
mechanisms of mangrove species in metal accumulation under different
environmental conditions. The accumulation of metals in plant tissues is
determined by the bioavailability of such elements in the sediment and by the
efficiency of the plant absorption and translocation of such metals in root and
vascular tissues. In this context, the present study has the objective of
evaluate the effect of different levels of salinity on the accumulation of
Chrome, Arsenio, Mercury, Lead; and into the anatomical, physiological and
biochemical traits of Laguncularia racemosa (L.) Gaertn. e Rhizophora
mangle L. Thus, propagules of L. racemosa and R. mangle were cultivated
during to 16 months in a vegetation green-house and afterwards exposed to
modified Hoagland and Arnon (1950) solutions, containing three distinct NaCl
concentration (3, 7 and 11 g L-1) with addition of 28 µg L-1 of Cr2O7, 2 µg
L-1 of As2O3, 10 µg L-1 of HgCl2 and 10 µg L-1 of PbCl2. The outcomes
were statistically analyzed by the Tukey test in 5% of significance; the
multivariate factorial analysis (FA); the linear discriminant analysis; and the
Spearman correlation test. We performed the following analysis: 1)
quantification of Chrome, Arsenio, Mercury and Lead in leaves, stem and
roots; 2) determination of the factor of translocation; 3) leaf anatomy; gas
exchanges; and 4) APX, CAT and SOD enzyme activity. The results show
that R. mangle traits is more affected by salinity than L. racemosa, exhibiting
a negative correlation to CAT activity, As stem content, and translocation
factor of As (stem/root). Moreover, the results show a positive correlation
between salinity and the Hg translocation factor (shoot/root). However, L.
racemosa show a higher sensitivity to the heavy metal concentration, mainly
to the Chrome, Arsenio and Mercury presence in roots. Those metals
positively influenced the stomatal density and conductance, and the vascular
bundle area from the central vein. The results also indicated that, under a
more saline condition, there is a higher absorption of Cr, Pb, As e Hg in L.
racemosa. Whereas higher concentrations of Cr and Hg were observed in R.
mangle under lower salinity conditions. The results highlight that L. racemosa
and R. mangle exhibit distinct anatomical, physiological and biochemical
responses to the different levels of salinity evaluated, and to the
bioaccumulation of Cr, Pb, As and Hg, as well.
Keywords: bioaccumulation, stress, L. racemosa, climate change, R.
mangle.
