Name: Juliana da Silva Penha
Type: MSc dissertation
Publication date: 04/09/2017
Advisor:
Name |
Role |
|---|---|
| Camilo Dias Júnior | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Alessandra Delazari-Barroso | External Alternate * |
| Camilo Dias Júnior | Advisor * |
| Geraldo Rogério Faustini Cuzzuol | Internal Alternate * |
| MÔNICA AMORIM GONÇALVES | External Examiner * |
| Valéria de Oliveira Fernandes | Internal Examiner * |
Summary: This paper studied the estimation of carbon biomass of autotrophic phytoplankton based on the biovolume method and its relationship with chlorophyll a. Were carried out two oceanographic campaigns, one in winter (July to August 2013) and one in summer (March to April 2014). Were sampled four transects along the Espírito Santo coast, the stations sampled within each transect were organized in eight isobaths, the samples were collected at two depths, both in the continental shelf region and in the slope. The plankton samples were collected using the Niskin bottle, then, preserved with 0.4% formalin and subjected to successive sedimentation processes. The organisms were counted in inverted microscope on the basis of the random field method, concomitant with the counts of the organisms were carried out the morphometric analyzes for the evaluation of the cell volume that were made according to the geometric shape that the algae resemble. To estimate the biomass on carbon (pgC. cell-1) was applied to different types of conversion of biovolume to carbon biomass. The data of the chlorophyll a of this research belong to AMBES Project and were obtained from the Database of Coastal and Oceanic Environments. Was analyzed biomass in carbon of 332 taxa in winter and 304 in summer, the taxa included representatives of the Classes Bacillariophyceae, Coccolithophyceae, Coscinodiscophyceae, Cyanophyceae, Dinophyceae, Fragilariophyceae Bacillariophyceae, Coccolithophyceae, Coscinodiscophyceae, Cyanophyceae, Dinophyceae, Fragilariophyceae, among others Classes. The relationship between biomass in carbon and biovolume showed to be significant, between the periods, between the depths and between the regions. The Class Cyanophyceae presented low number of species, however, presented one of the highest values in biomass in carbon, represented mainly by the cyanobacterium of the Genus Trichodesmium. In the region of the continental shelf, Coscinodiscophyceae and Cyanophyceae showed in highest values biomass terms the, in the slope region and in the subsurface were Cyanophyceae and Coccolithophyceae classes and second depth were Coscinodiscophyceae and Bacillariophyceae. Was possible to observe a spatial and temporal variation of the biomass in carbon, the highest carbon biomass values found were in the summer, subsurface and continental shelf. The relationship between biomass in carbon and chlorophyll showed to be
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significant, but low. Was possible to observe significant relationships between these two methods of biomass estimation, however, with low values of correlation coefficient, in the winter (0.36; r2: 0.10), on the continental shelf in winter (0.40, r2: 0.22) and in the summer slope (0.57; r2: 0.32). The great diversity of techniques for estimating phytoplankton biomass offers a wide variety of data accuracy, and combinations of biomass estimate techniques may be the best approach to avoid the limitations of different methods estimates of biomass in carbon by means of the biovolume method have proved to be efficient is very important for physiological and ecological studies in marine environments.
Keywords: Organic carbon. Espírito Santo. Marine Phytoplankton. Relationship of methods. Spatial and temporal variation.
