ABSTRACT
Characteristics such as calcareous morphology and life cycle are used to understand the ecology of calcified rhodophytes. However, there is limited information regarding their chemical profiles and biological activities. Therefore, a systematic review (PRISMA) was conducted to assess the influence of the chemistry of calcareous rhodophytes on ecological interactions in the marine environment. The keywords used were: ["Chemical AND [Ecology OR Interaction OR Response OR Defense OR Effect OR Cue OR Mediated OR Induce]"] AND ["Red Seaweed" OR "Red Macroalgae" OR Rhodophy?] AND [Calcified OR Calcareous] in Science Direct, Scielo, PUBMED, Springer, Web of Science, and Scopus. Only English articles within the proposed theme were considered. Due to the low number of articles, another search was conducted with three classes and 16 genera. Finally, 67 articles were considered valid. Their titles, abstracts, and keywords were analyzed using IRaMuTeQ through factorial, hierarchical and similarity classification. Most of the studies used macroalgae thallus to evaluate chemical mediation while few tested crude extracts. Some substances were noted as sesquiterpene (6-hydroxy-isololiolide), fatty acid (heptadeca5,8,11-triene) and dibromomethane. The articles were divided into four classes: Herbivory, Competition, Settlement/Metamorphosis, and Epiphytism. Crustose calcareous algae were associated with studies of Settlement/Metamorphosis, while calcified algae were linked to herbivory. Thus, the importance of chemistry in the ecology of these algae is evident,and additional studies are needed to identify the substances responsible for ecological interactions. This study collected essential information on calcified red algae, whose diversity appears to be highly vulnerable to the harmful impacts of ongoing climate change.
ABSTRACT
This study aimed to examine the benthic structure of Guanabara Bay's (GB) rocky shores through Functional Diversity (FD) perspective. Over a five-year period, benthic communities were periodically examined using photographic samples from the meso-littoral zone. FD were analysed using the Rao Index of marine macroalgae and benthic invertebrates' functional groups (FGs) and their relationship was investigated through null models, considering temporal, geographical, and environmental variations. The entrance site exhibited exclusive FGs and overlap niches more than expected by chance, while the inner site had a higher frequency of Bacterial Biofilm and predominance of competitive exclusion. Orthophosphate and nitrate showed significant correlations with FGs inside the bay, whereas average irradiance and rainfall were at the entrance. A functional gradient was registered, with higher Rao's Index values at the entrance compared to the inner site, probably due to increased anthropogenic disturbance and abundance of FGs with opportunistic life strategies inside GB.
Subject(s)
Bays , Animals , Anthropogenic Effects , Environmental Monitoring , Invertebrates , SeaweedABSTRACT
Guanabara Bay, the second largest bay on the Brazilian coast, has tropical to subtropical, hypereutrophic water conditions. A survey of the macroalgae flora conducted over the past 200 years (1800-2013) yielded a list of 245 species, which represents 15.7% of the total macroalgae recorded in the Tropical Western Atlantic, while comprehends 29.9% and 50.2% of the marine flora in Brazil and Rio de Janeiro, respectively. When evaluating the macroalgal list throughout different periods, it is noticeable the gradual loss of biodiversity as anthropization increased over the last two centuries. The use of phytogeographic indexes and beta diversity confirmed the negative changes in macroalgae assemblages as a response to increasing environmental degradation. The use of floristic surveys to establish the reference conditions employing historical data and/or regionally referenced prove to be an efficient tool using macroalgae as an ecological indicator for water quality.
