Abstract in English:

ABSTRACT Marine pigments are more commonly used in food, pharmaceuticals, aquaculture and cosmetics industries. Marine pigments have a significant economic importance, constituting a multimillion-dollar industry that is still growing. Considering this, we decided to conduct a descriptive study of the photosynthetic pigments in surface sediments from the continental shelf and slope of 14 sites located in the northwestern Gulf of Mexico, obtained during October-November 2012. These pigments were analyzed using high-performance liquid chromatography. At least one pigment was detected in 10 of the samples examined, and a total of six pigments were identified, including three photosynthetic pigments and three chlorophyll-a degradation products: pheophorbide-a, pyrophaeophytin-a and phaeophytin-a. The pigments with the highest concentration were β-carotene and pheophorbide-a. Significant pigment concentrations were observed in inshore areas exposed to the influence of river discharge (Bravo and Soto La Marina) and Laguna Madre. The pigment composition and concentration were influenced by depth, temperature, salinity, and nickel concentration. Finally, a correlation between Ni, an indirect hydrocarbon contaminant marker, and pigment concentrations was observed. A deeper understanding of marine pigments certainly will fuel advances in biotechnology and bioengineering. We find it crucial to recognize the interactions between marine pigments and other ecosystem components. Despite pigment diversity, exploration in this field is still in its first stages, with many marine compounds awaiting further exploration.

Abstract in English:

ABSTRACT The Hunga Tonga Hunga Ha’apai eruption of January 15th, 2022, was a rare geological event, resulting in atmospheric pressure waves being recorded around the world, along with sea level fluctuations. This research aims to analyze the tsunami and pressure waves observed in the Caribbean and adjacent regions, which were generated by this eruption. These kinds of perturbations are uncommon and have not been seen in many occurrences, let alone with global implications. Modern instrumentation in the Caribbean and adjacent regions, including both barometers and sea level stations, provided a unique opportunity to observe and analyze this event. A comprehensive review of the observations recorded in the Caribbean and adjacent regions linking the barometric observations to sea level perturbations, including observations of the lead/lag relative to the barometric pressure spikes and the frequency content of observable sea level perturbations, will be shown in this study. For instance, most of the stations in this study recorded six barometric spikes, of which the first two generated a significant sea level observation. Circumstances complicating observations, such as interference from factors, e.g. a strong cold front and lack of standardization, will also be discussed. This study, which will integrate observations from across the Caribbean and adjacent regions, aims to better understand the nature of this unique event and how it was observed in the region. As such, this research can offer insight into the factors that may influence volcanic tsunamis, which is invaluable for developing tsunami warning and response protocols.

Abstract in English:

Abstract Exotic and invasive species are considered the second major cause of biodiversity loss in the world. In addition to damage to native biodiversity, impacts caused by exotic species can affect ecosystem services and socioeconomic activities. The Patos-Mirim lagoon system (PMLS) has great ecological importance and supports important socioeconomic activities in southern Brazil. This study aimed to compile historical records of the occurrence of exotic aquatic species in PMLS and to synthesize this bioecological information, means of introduction of such species, main impact mechanisms, and undertaken management measures. The data were obtained by a bibliographical review using the official list of Invasive Exotic Species of the Rio Grande do Sul State, the National Base of Invasive Exotic Species (Hórus Institute), and scientific information. We found records of 26 exotic aquatic species in the PMLS. Actinopterygii was the most representative (11 species), followed by Hydrozoa (three), Malacostraca (two) and Bivalvia (two), and other eight classes with only one species each. In total, nine species that had been registered in the study area were ignored by the official list of exotic species for the region. The main ways of introduction were associated with socioeconomic activities, such navigation and aquaculture. The main impact mechanisms of exotic aquatic species refer to competition (85% of species) and habitat modification (46% of species). Despite the undertaken management measures, occurrence of exotic aquatic species is growing and may seriously threaten native biodiversity and its ecosystem services.

Abstract in English:

Abstract Quorum sensing (QS) is a communication mechanism between bacteria, mediated by signals released at high cell densities, which regulates bioluminescence, virulence, and biofilm formation. By inhibiting QS, these processes can be controlled when they become undesirable, as in infectious diseases and during biodeterioration of materials. In this context, this study investigated the Quorum Sensing Inhibition (QSI) activity in 60 strains of marine Gammaproteobacteria isolated from samples of the South Atlantic Ocean. Initially, the bacterial strains were screened using plaque assays, with Chromobacterium violaceum LAMA 0447 and Serratia marcescens LAMA 1170 as indicator strains. Subsequently, seven selected bacteria were further evaluated via luminescence test with Aliivibrio fischeri, considering both cultivation time and mixed cultures with A. fischeri. Later, three strains were investigated regarding the chemical nature of their substances with QSI activity via ultrafiltration and proteinase K treatments. Finally, the genome of one of these strains was examined for the identification of genes related to QSI activity. In total, 16 strains exhibited QSI activity in plaque assays, and the activity of seven of these strains was further assessed in quantitative assays. Higher activity was observed in supernatants obtained after 48 hours of cultivation for six strains and from mixed cultures with A. fischeri. Treated supernatants of three strains allowed us to infer that, for Halomonas olivaria LAMA 0626, the substances responsible for QSI are probably enzymes. For the other two strains, belonging to the Marinobacter genus, more than one type of substance seems to be involved: (1) at least one enzyme and (2) non-protein low molecular weight molecules (< 10 kDa). Genes identified in M. excellens LAMA 0842 support this hypothesis. In summary, marine bacteria from the Gammaproteobacteria class can disrupt the communication of other bacteria, which could form the basis for the development of novel microbial control products.

Abstract in English:

Abstract This study provides an in-depth examination of the ecological interaction between the non-native Diadumene lineata (Verrill, 1869) sea anemone, and the Polysyncraton amethysteum Van Name, 1902 colonial ascidian. We documented the nature of their interactions using systematic field observations carried out in their natural habitat along the rocky shores of Ubatuba, located on the northern coast of São Paulo State, Brazil. Our findings reveal that these two species engage in a complex relationship that may offer several adaptation strategies and ecological benefits, such as increased habitat stability and enhanced nutrient availability. We discuss how the presence of ascidians may provide shelter for the sea anemone. Furthermore, this study highlights broader implications of non-native species on rocky shore ecosystems. The introduction of non-native species can disrupt existing relationships between native organisms, potentially altering community structures and ecological balances.