Name: Patricia Sarcinelli Stelzer
Type: MSc dissertation
Publication date: 15/04/2021
Advisor:
Name |
Role |
|---|---|
| Angelo Fraga Bernardino | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Ana Carolina de Azevedo Mazzuco | External Alternate * |
| Angelo Fraga Bernardino | Advisor * |
| Ciro Colodetti Vilar de Araujo | External Alternate * |
| Jean-Christophe Joyeux | Internal Examiner * |
| Sergio Antonio Netto | External Examiner * |
Summary: Abstract: Rhodoliths are free-living and morphologically diverse
marine calcareous algae that are commonly distributed over the
continental shelf seafloor. They increase the seabed structural
complexity and are of potential value as feeding or reproductive
grounds for a myriad of marine fauna. The higher structural
seabed complexity within rhodolith beds (RB) may increase overall
benthic diversity through the creation of microhabitats, but this
rela-tionship has been rarely explored within RB worldwide. Here
we compared benthic macrofaunal assemblage structure on rhodolith
beds and within unconsolidated sediments below (infaunal
organisms under rhodoliths), between high and low-density beds.
The total macrofaunal abundance inside rhodoliths was 16-fold
higher when compared to the abun-dance of sediment infaunal
organisms below RBs. These differences were driven by habitat
complexity that directly influenced the higher macrofaunal
diversity in the rhodoliths when compared to unconsolidated
sediments. Carbonate percentage influenced macrofaunal structure
in sediments, WHEREas proteins and carbohydrates in organic
matter were key fac-tors in high-density stations suggesting that
rhodolith density influence sediment organic quality. In
contrast, macrofaunal diversity, abundance, and functional
diversity were higher in low-density stations in the sediment.
RBs density and rhodolith nodule morphology ex-plained
macrofaunal, taxonomic and functional diversity in the rhodolihs.
Low-density (55 ± 26.0 m-2) RBs with discoid-shape nodules had
higher macrofaunal abundance dominated by crustaceans, in
contrast to spheroidal nodules with higher internal volume in
high-density beds (211 ± 7.3 m-2) that were dominated by
Annelida and with higher taxonomic and func-tional diversity. Our
study indicates that benthic communities change markedly in
response to rhodolith bed density and nodules morphology, and
provide critical habitat for several unique benthic species that
are not encountered in unconsolidated sediment below these beds
on continental shelf depths. Key words: Rhodoliths, benthos structure, functional groups, MPA,
Brazil.
