Resumo em Inglês:

Abstract Formed during marine regression periods, shelf valleys (SVs) are preterit river flows on the exposed continental shelf. This study investigates the influence of tectonic activity on forming these important morphological features. This research combines bathymetric, magnetometry, and seismic data to analyze the role of tectonic events in SV genesis and positioning. The bathymetric dataset provides information on SV locations and geometries along the continental shelf, whereas the 2D seismic sections illustrate that SVs formed above post-rift faults that reached Quaternary deposits. Aeromagnetic data indicates that the shallow and deep structures of the basement and sedimentary column-controlled SV locations and evolution. The multi-data integration demonstrates a strong correlation between neotectonic structures and SV location and geometries from the inner shelf (−25 m) to the shelf break (−55 m). The analysis of the 2D seismic data indicated that high-angle faults, formed under a strike-slip tectonic regime, primarily affected the Middle Miocene deposits beneath the shelf valleys. The formation of “negative flower pattern structures” was identified as a primary structural mechanism that contributed to SV formation. Reactivation events that occurred from the Late Cretaceous onwards, gave rise to these faults, which control SV formation and the capture of preterit drainage on the exposed continental shelf. The SV geometries display straight patterns and abrupt changes in direction (90°) due to the interplay of the NE-SW and NW-SE aligned faults. The results reinforce the importance of considering tectonic activity in the formation and evolution of shelf valleys.

Resumo em Inglês:

Abstract “For more than two decades, the Philippine government has protected the giant clams (Bivalvia: Cardiidae: Tridacninae) from exploitation and trade. However, there still is lack of information on the impact of these protective measures in conserving the species richness and density, especially in Palawan, the country’s last stronghold of these reef-associated bivalves. Hence, to assess the species richness and density of giant clams in Palawan, we conducted 57 photo-transect surveys in six sites covering 12,325 m 2. Out of these transect, 15 measured 5 × 25 m and the rest measured 5 × 50 m. For historical trends in the population of giant clams in Palawan, we used six published papers obtained from online platforms, 13 reports, and five undergraduate theses archived in local libraries. Information derived from recent field surveys indicated high variations in species richness (2 to 5 species) and densities (0.1 to > 3.6 ind.100 m -2). Historical data starting from 1984, including recent fieldwork, indicated very low densities and a declining trend. The current status suggests that giant clam populations’ viability and the reefs’ health are threatened. Effective mechanisms are needed to safeguard and enhance the remaining giant clam populations.”

Resumo em Inglês:

Abstract This study aimed to investigate the biogenic composition of calcium carbonate (CaCO 3) in pelagic sediments in the Santos Basin over the past 140,000 years. The content and composition of CaCO 3 in different sediment fractions were evaluated, including the bulk sample, coarse fraction (foraminifera), medium fraction (juvenile foraminifera and fragments), and fine fraction (nannofossils), to determine the contribution of each fraction to the carbonated sediment composition. We found that variations in CaCO 3 levels were closely linked to glacial and interglacial periods, with higher values during interglacial periods and lower values during glacial periods. The main factor controlling the variation in CaCO 3 was dissolution, which was mainly linked to the influx of more corrosive southern water masses. Fluctuations in CaCO 3 levels were influenced by variations in productivity and dilution caused by terrigenous sediments. Nevertheless, it is noteworthy that both processes held a relatively minor impact compared to dissolution. Productivity primarily contributed to increased dissolution rates. During periods of low sea levels, dilution by terrigenous sediments became significant (similarly, the influence of the La Plata River plume was notable). However, due to the limited presence of riverine supply in the study area, which contributes directly to major dilution influences, fluctuations in terrigenous materials were considered of lesser magnitude than those caused by dissolution. The nannofossils were found to be the largest contributor to the total CaCO 3 composition, as they were the fraction least affected by the dissolution process. Overall, our results provide insights into the factors influencing CaCO 3 accumulation in marine sediments and can be used as a tool to determine changes between climatic cycles over time.

Resumo em Inglês:

ABSTRACT Several studies have reported on the presence of litter on beaches and in the oceans, but this represents the smallest part of the litter that ends up in the sea. Little is known about the litter that settles on the ocean floor, especially near coastal regions. Thus, this study quantified, classified and determined possible sources of subtidal benthic marine litter input off the coast of Rio de Janeiro, Brazil. Different sites were selected in Guanabara Bay, an area with the greatest industrial and population concentration in the state of Rio de Janeiro, and on the coasts of Costa do Sol and Costa Verde, where tourism represents the main economic activity. Material was collected by scuba diving at depths of between 5 and 15 meters at 31 sites distributed among the study areas. A total of 1, 209 items was found, with Guanabara Bay having the highest average concentration (92.40 items/km2), followed by Costa do Sol and Costa Verde (14.15 items/km2 and 9.91 items/km2, respectively). Plastic materials are the most representative solid waste (55.08%), followed by metals (14.97%) and fishing gear (12.48%). Results indicated that local activities affected the composition of the marine litter on Costa do Sol and Costa Verde, whereas in Guanabara Bay, anthropogenic material carried by rivers influenced the marine litter composition at certain locations in addition to local activities. Environmental education actions associated with tourism and fishing activities and better waste management are necessary to minimize the presence of litter in subtidal benthic environments.

Resumo em Inglês:

ABSTRACT Seaweed blooms pose a compelling governance challenge caused by the new environments of the Anthropocene. Along the Quintana Roo coastline, nestled in the heart of the Caribbean, the onset of extensive Sargassum infestations began in late 2014, posing a formidable environmental management dilemma for state and federal authorities. This study describes the institutional responses elicited by the Sargassum influx on Mexico’s Caribbean shoreline, particularly focusing on Cancún and the Riviera Maya. It proposes ecological reflexivity as a promising governance principle for institutions faced with increasingly complex and unforeseeable circumstances, such as the massive arrivals of Sargassum. Based on a comprehensive analysis of national press reports, active participation in forums and seminars, and in-depth interviews, our research identifies three distinct governance phases. We explore these phases considering the concept of ecological reflexivity. Our findings make a strong case for acknowledging institutional errors and shortcomings as an indispensable aspect of formulating effective strategies to combat unexpected and unfamiliar phenomena such as seaweed blooms. Moreover, governance strategies for dealing with Sargassum in Quintana Roo should not only consider responding to human interests and sustaining the tourist industry. Instead, they should encompass an approach that considers the interplay between human and non-human components within the socio-ecological system.

Resumo em Inglês:

ABSTRACT Along the coast of the state of Pernambuco, NE Brazil, the presence of coastal outcrops aligned with the shoreline and distributed above and below the mean sea level is remarkable. These outcrops were sampled, and petrological, isotopic, and geochronological analyses were integrated to investigate the local effects of the Holocene sea-level fluctuations. The results indicate that the rocks are recent (< 8ka), formed by cementation of beach sands (magnesian calcite cement, predominance of quartz and presence of marine bioclasts, signs of compaction, fractures, and dissolution), in a tropical climate and warm waters, which allows to classify them as typical examples of beachrocks. The carbonate cement consisted of Mg-rich calcite with values ranging from −1.1‰ to 3.5‰ for δ13C and from −0.9‰ to 0.5‰ for δ18OVPDB. These isotopic values are typical of marine carbonate cemented deposits in shallow marine environments under freshwater influence (meteoric vadose environment). In these conditions, the cementing processes occurred in the intertidal zones, which reinforce the use of these data as indicators of ancient sea levels. The sea level fluctuations could be divided, in chronological order, into three different phases, starting with a rapid sea level rise followed by a relative stabilization at a maximum level and, finally, a decreasing phase. Recent sea level fluctuations in Pernambuco are represented by beachrocks with ages between 8 ka and 800 years and a maximum level of 2 to 3 meters above the present mean level. In scenarios of a near future with a general global sea level rise pattern, significant local geomorphological changes may occur, which means a great future challenge to society.

Resumo em Inglês:

ABSTRACT The South Pacific hake, Merluccius gayi, is an ecologically and economically important species in Ecuador. However, studies regarding its feeding habits remain scarce. This study aimed to characterize the food and feeding habits of M. gayi in the Ecuadorian Pacific Ocean by sex, sexual maturity stages, size classes, and years. Hakes obtained (n = 2993) from industrial fishing (captured with seine nets) were analyzed from September 2013 to December 2014. Their diet was composed of 27 prey species. The most important prey was the euphausiid Nyctiphanes simplex (52%) and the same hake species (M. gayi; 31%) according to the prey-specific index of relative importance (%PSIRI), making this species a cannibal predator. Results show no significant dietary differences between female and male hakes or immature and mature males, but found differences between immature and mature females and individuals from four size classes and hake between 2013 and 2014. According to Levin’s Index, the species showed a low trophic niche breadth (Bi = 0.03), making it a selective specialist mesopredator with high specialization. The trophic overlap analysis based on Jaccard’s index by sex was low (J = 0.23) for indetermined individuals, moderate (J = 0.59) for males and females, and high (J = 0.78) for immature females and males; moderate values were noted for size classes (J = 0.42-0.63) and low for years (J = 0.31). Based on the Cortés index, the trophic level totaled (TLk = 3.22), indicating that this species is a primary and secondary carnivore mesopredator. This information supports the understanding of the relations between predators and prey and the flow of nutrients and energy in marine ecosystems, which serve as a base for ecosystemic fishing management.

Resumo em Inglês:

Abstract The COVID-19 pandemic led to a reduction in human mobility, known as “anthropause.” Few studies have compared birds’ community patterns between lockdown and “new normal” periods, especially in extremophile environments. This study presents the first baseline by monitoring coastal birds on 10 beaches along the largest hypersaline lagoon in South America. The birds were counted in September and October 2021 (during a lockdown period) and in October 2022 (after the lockdown – “new normal”) during the morning. The continuous route transect methodology was applied by the same observer in all beaches. The Analysis of Covariance (ANCOVA) was used to investigate the response of community abundance to urbanization (raster-based variable) and time of COVID-19 pandemic (lockdown vs. new normal). Rarefaction curve and Permutational Analysis of Variance (PERMANOVA) were used to compare community richness and composition, respectively, between lockdown and new normal periods. Generalized Linear Models (GLM) with negative binomial distribution were applied to test the effect of the same predictors on the three more abundant species. The bird community structure and composition did not change when comparing lockdown and new normal periods, mainly due to dominance of synanthropic species. Among species-specific responses to lockdown, the Southern Lapwing Vanellus chilensis was more abundant during the lockdown on six of the nine beaches where it occurred. Oppositely, the Kelp Gull Larus dominicanus and the Neotropic Cormorant Nannopterum brasilianus were more abundant in new normal period, reinforcing that these species benefit from human subsidies. This may provide a unique opportunity for science-based sustainable ecotourism activities in urban areas with synanthropic species, capitalizing activities such as birdwatching, that would certainly contribute to environmental education actions.

Resumo em Inglês:

Abstract Sponge-ophiuroid ecological associations, which are important in the dynamics of marine populations and communities, have been recorded for a long time. In this study, we report new records of interactions between sponges and ophiuroids, which were obtained by analyzing biological collections, to increase knowledge about the associations between these animals. The study observed 14 interactions between sponges and ophiuroids, eight of which are new to science: Ophiocnida scabriuscula and Agelas sp., Ophiothrix sp. and Monanchora arbuscula, Ophiactis quinqueradia and M. arbuscula, O. quinqueradia and Callyspongia ( Cladochalina) aculeata, Ophiactis savignyi and Agelas dispar, O. savignyi and M. arbuscula, O. savignyi and Topsentia ophiraphidites, and O. savignyi and Dysidea etheria. The specimens found were collected in four areas of the northeastern Brazilian coast (tropical southwestern Atlantic), including a conservation area and a mesophotic coral ecosystem. Thus, the continuation of studies and the implementation of conservation strategies for these environments are essential. Finally, the importance of biological collections as a crucial data source for biodiversity studies is reinforced.

Resumo em Inglês:

ABSTRACT In this study, the length-weight relationships (LWRs) and length-length relationships (LLRs) of 16 marine fish species-important component of fishery production models-were estimated. The specimens were collected monthly from commercial gillnet fisheries from November 6, 2018 to October 30, 2019 in Vietnamese waters. In total, 7,426 individuals had their total length (TL), fork length (FL) and total body weight (W) measured. LWRs were calculated using the logarithmic transformation of the linear regression equation logW = loga + b*logTL, while LLRs were determined using a linear regression model: TL = a + b*FL. In addition, 95% confidence intervals (CIs) were estimated for the model parameters. The results showed that all regression parameters were highly significant (p < 0.001), with coefficients of determinations (R 2 ) > 0.9412 for all species. The a (intercept) values ranged from 0.0025 to 0.4, and the b (slope) values ranged from 2.53 to 3.28. TL and FL were highly correlated (p < 0.001 and R 2 > 0.9422 for all parameters), and a and b ranged from -9.12 to 15.85 and 0.87 to 1.45, respectively. The results provide the key morphology parameters, which are beneficial for fishery researchers and managers in stock assessment, administration and conservation.

Resumo em Inglês:

ABSTRACT Sewage pollution is an increasing problem for Perna perna mussel farmers in Brazil, and there is an urgent need to adopt post-harvest treatments, such as depuration, to reduce the associated microbiological risks. However, depuration of this species has been discouraged by experiences showing that the animals usually spawn during this procedure, bringing difficulties for water treatment and making them lighter, weakened, and undesirable to be traded as a live product. This study aimed at developing a protocol to prevent mussels from spawning by modulating the water temperature during depuration. For one year (from 2021-07-07 to 2022-06-29), market-size mussels harvested from the Brazilian southern coast were divided into groups of five and immersed during 50 hours in sets of experimental units (15 L acrylic aquariums) that emulated depuration tanks with different water temperatures (ranging from 8°C to 31°C). During this period, the experimental units were inspected nine times to check for spawning/spawned mussels. Analysis of the overall results showed that 21 (95.5%) out of the 22 assays resulted in mussels spawning and that this behavior was mostly recorded (80.3%) within the first 5:30 hours of the assays. The models developed (binary logistic regression) indicate that conditioning the depuration water to temperatures 5°C lower than those registered at the harvest site holds the potential to reduce the chances of spawning by more than 50%, and these chances drop to 8.2% when this difference reaches 10°C. Further studies are needed to show how reducing water temperature during depuration influences its efficiency in terms of pathogen reduction, aiming to define the best protocol to optimize microbial removal and minimize spawning.

Resumo em Inglês:

ABSTRACT This study encompasses the description and evaluation of the length-weight relationship of 104 demersal fish species caught by bottom trawlers targeting shrimps on the southeast continental shelf of Brazil from 2004 to 2006. The regression criteria describing the length-weight relationship for each species were classified as approved (met the criteria), approved with reservations (partially met the criteria), and not approved (did not meet the criteria) based on linear regression parameters to determine whether length is a viable predictor of weight. A total of 141,433 individual fish, comprising 44 families and 104 species, were sampled; the beta parameter (± se) varied from 0.22 ± 0.12 to 3.94 ± 0.19, and the alpha parameter varied from -4.09 ± 0.04 to 0.89 ± 0.02. In total, 22 species were not identified by a recent large survey (2019) conducted in the study area. The results of this study are significant for the management of fishery resources, mainly due to the occurrence of unusual species, the economic importance and enormous effort exerted by the trawling fleet in the region, and the substantial sample size, in which a large number of individuals per species were caught.

Resumo em Inglês:

ABSTRACT The objective of this study was to identify the squids caught by shrimp trawlers in Sergipe and to describe their populational structure. Four samples were obtained monthly from commercial trawlers based in Pirambu-Sergipe (May/2015-May/2016). Each squid found was separated, identified, weighed individually (wet weight - WW in g) and had its mantle length (ML; cm) and total length (TL, including tentacles; cm) measured. One specimen of Doryteuthis pleii was captured (23.3 cm ML mature male), as well as 152 specimens of Lolliguncula brevis (1.5˗6.7 cm ML). The linear relation between TL and ML of L. brevis was TL=5.1173+2.6190ML (positive allometry) and the power relation between WW and ML was WW=0.1453ML2.5353 (negative allometry). For L. brevis, there were two cohorts in the area during the period analyzed. Studies on the biology of cephalopods are scarce in northeastern Brazil, especially considering that these species are present in the bycatch of shrimp fishing and that the global conservation status of L. brevis is data deficient (DD) according to the International Union for Conservation of Nature (IUCN).

Resumo em Inglês:

ABSTRACT Magnetic experiments have provided insight into the preservation of magnetite in sediments of the Inner Sea of the Maldives during early diagenesis. In this study, we present high-resolution remanence data on the upper 15 meters of the sedimentary record and a detailed magnetic characterization of discrete samples from the top 5.5 meters of the International Ocean Discovery Program (IODP) Site U1471 record. Based on magnetic experiments, it can be concluded that magnetite is rapidly reduced, with a large decrease in natural remanent magnetization (NRM) related to destruction of primary NRM below the upper two meters of the sedimentary record. In thermomagnetic experiments, the appearance of a greigite signal at 3.06 meters below sea floor (mbsf) suggests that current diagenesis could imprint nearly 100 kry of error on the chronology based on magnetostratigraphy. Furthermore, based on X-ray fluorescence data, it can be concluded that magnetite reduction did not affect the Fe record.