Marlon Carlos França

The purpose of this work was to identify and correlate vegetational and sedimentary changes with sea level fluctuation events and climatic changes that have occurred over the last two thousand years at the mouth of the Jucu River (ES), southeastern Brazil. Thus, a sedimentary core was collected with a depth of 190 cm and was used to perform pollen, sedimentary, and C-14 dating analyses. The results showed the formation of four zones. The first zone started around 2212 cal years BP, with sandy sediments, which is indicative of high energy flow. The analysis of the palynological profile indicated the presence of herbaceous vegetation. In the second and third zones, which correspond to the period of ±2210 to ±460 cal years BP, there was a predominance of silt-sandy sediment, with the installation of the mangrove. The fourth zone considers the period of ±460 cal years BP until the present, marked by the presence of silt-clay sediment and predominance of herbaceous vegetation. Furthermore, the presence of Laguncularia and Rhizophora remained almost continuous during the fourth zone.

Understanding the impact of monsoonal oscillations during past climatic changes in the Arabian Sea is crucial for improving climate model predictions under ongoing global warming. This study investigates whether millennial-scale climate shifts in Greenland, specifically Dansgaard–Oeschger events 12–11, affected the Indian Ocean monsoon system and the associated productivity and oxygen minimum zone (OMZ) dynamics in the northwestern Arabian Sea. In the Arabian Sea, DO stadials correspond to reduced water-surface productivity, well-ventilated intermediate water masses, and a weakened or absent OMZ. Contrarily, DO interstadials are distinguished by enhanced water-surface productivity, a reorganization of intermediate water masses, and a reinvigoration of the OMZ. Eleven sediment samples from ODP Site 721A were analyzed using a multiproxy approach combining total organic carbon, C/N ratios, bulk-sediment isotopes (δ¹⁵N, δ¹³C), and the relative abundances of Globigerina bulloides and Globigerinoides ruber, complemented by isotopic data (δ¹³C, δ¹⁸O) from G. ruber shells. Further Mg/Ca–δ¹⁸O and δ¹⁸O_sw measurements were included to refine the reconstruction of surface-water hydrography linked to productivity changes. Results reveal significant oscillations in water-surface productivity and OMZ intensity, modulated by shifts in monsoon strength and water-column ventilation. Enriched δ¹⁵N values, elevated TOC, and increased G. bulloides relative abundances reflect intensified denitrification and organic matter preservation under a stronger southwest monsoon, whereas depleted δ¹⁵N, reduced TOC, and higher G. ruber abundance indicate enhanced ventilation and a weaker OMZ under northeast monsoon dominance. These findings provide new evidence that refines the paleoceanographic history of the Arabian Sea. Additionally, they demonstrate that high-latitude climatic forcing during DO events modulated Arabian Sea monsoon dynamics and oxygenation through strong interhemispheric teleconnections.

This study examined the population ecology of bivalve mollusks on Central Beach in Piúma, southern Espírito Santo, Brazil, over one year (August 2018 to July 2019). Sampling was conducted along four transects perpendicular to the shoreline, with sediment characteristics and benthic community structure analyses. 2,104 individuals were identified, representing 5 orders, 8 families and 13 species. The most abundant species were Anomalocardia flexuosa (39.78%), Strigilla carnaria (28.90%), Donax gemmula (11.93%), and Tivela mactroides (11.07%). The consistent presence of juveniles and recruits indicated that the area serves as a natural nursery for these species. Transect A, closest to the mouth of the Novo River, showed the highest organic matter content in the sediment and the most significant dominance of A. flexuosa, which was positively correlated with organic matter levels (p< 0.0001). Conversely, alpha diversity was negatively correlated with organic matter content (p= 0.0497). Sediment granulometry was uniform across transects, mainly of moderately sorted fine sand. Rainfall did not significantly affect ecological indices or the abundance of dominant species, suggesting that the bivalve community is resilient to seasonal climatic variations. These results highlight the environmental significance of Central Beach in Piúma as a vital estuarine habitat, particularly for A. flexuosa, and emphasize the need for integrated coastal management strategies that account for both marine and continental influences.

Climatic changes and sea level variations have had a significant impact on the mangroves along the Brazilian coast during the Holocene. The present study focused on understanding the specific factors that have determined the establishment and expansion of mangroves in a subtropical estuary of southern Brazil (Babitonga Bay, State of Santa Catarina-SC), as well as their response to climate change and sea level variations during the late-Holocene. In this study, we carried out sedimentary analysis, palynology, and radiocarbon dating (C-14) to paleoenvironmental reconstruction of the last 1500 cal. year BP. Three facies associations were identified, indicating a progradational succession where a tidal flat was developed at the margin of the estuary. During the first phase, between at least 1440 and ±1286 cal. year BP, the area was characterized by a subtidal environment. The presence of Laguncularia pollen grains since ± 1390 cal. year BP indicated favorable conditions for mangrove establishment in proximity to the study site. Subsequently, around ± 1286 cal. year BP, the tidal flat developed, reaching the present-day shoreline, facilitated by the relative sea level drop. Avicennia trees were established on the tidal flat since ± 1273 cal. year BP, and the establishment of Rhizophora trees occurred in the most recent decades. This mangrove succession developed in Babitonga Bay following a temperature gradient, associated with low-temperature tolerance, and likely its establishment is associated with a temperature increase during the late-Holocene, that caused a migration of the southern limit of the mangrove in the subtropical zone to higher latitudes. Furthermore, the relatively slow expansion of mangroves upstream of Babitonga Bay also may have been controlled by the suitable salinity and substrate conditions, which were favored by the relative sea-level fall during the late-Holocene.

Context: Balistes capriscus is relevant for fishing worldwide, but there is no consistent information on the maintenance of the species in a captive environment. Aims: Develop protocols for the reproduction of the species in aquaculture systems, contributing to the maintenance of the supply in the commerce through captive breeding. Methods: A Balistes capriscus couple was selected on the basis of behavioural observations. Nutritional and environmental stimuli were invested in obtaining natural spawning. After reproduction, the larvae were regularly observed under an microscope to monitor the ontogenic development. In larviculture, feeds based on Brachionus plicatilis (10 mL-1) and Nannochloropsis oculata (150 000 cells mL-1) and pate formulated with Artemia salina, Nannochloropsis oculata, sardines and commercial feed were evaluated. Key results: The eggs had a diameter of 667.5 µm (±21.66) and formed a mass adhered to the substrate. Newly hatched larvae had a total length of 1653.63 µm (±213.97). The first food intake was evidenced 72 h after hatching; however, larvae did not survive more than 6 days. Conclusions: The reproduction in laboratory of the species is viable; however, larviculture remains a limiting factor. Implications: The success in captive breeding is essential for the introduction of B. capriscus in aquaculture, and for the conservation of the species.

Projections of the impacts of modern Relative Sea Level (RSL) rise on estuarine mangroves should be supported by coastal topographic data and records of mangrove dynamics under past RSL change. This work identified inland and seaward mangrove migrations along the Jucuruçu River (Bahia, Northeastern Brazil), during the Holocene based on sedimentary features, palynological and geochemical (δ¹³C, δ¹⁵N, C/N) data integrated with digital elevation models. During the Middle Holocene, in response to RSL rise, the estuary saw mangrove forest establish up to ~37 km inland. RSL stood between ‐1.4 (+0.36/‐2.2 m) and +1 (2.19/0.2 m) around 7400 cal yr BP, and rose to a highest position of +3.25 (4.22/2.45 m) reached around 5350 cal yr BP. That marine incursion caused the inland replacement of freshwater vegetation by mangroves on tidal flats. Since then, the estuary experienced RSL fall, reducing inland tidal water salinity towards the Late Holocene, making that the mangroves were replaced by freshwater floodplain vegetation. Today, in the seaward part of the estuary near its mouth, mangroves occupy an area of ~10 km² along tidal channels. Considering a RSL rise of 98 cm up to the end of the 21^st century, at a rate significantly higher than that of Middle Holocene RSL rise (1.5 mm/yr) and fall (0.6 mm/yr), the current mangrove substrates are expected to drown and/or eroded near the coast, while new mangroves may establish inland, at topographically higher tidal flats in nowadays freshwater‐tidal zones. Mangrove area could expand over 13 km² of coastal and flood plain. Following the same interaction between RSL/climate changes and Holocene mangrove dynamics, such upstream mangrove migration may be attenuated or intensified by changes in fluvial discharge. © 2019 John Wiley & Sons, Ltd.

França, M.C.; Cohen, M.C.L.; Pessenda, L.C.R.; Francisquini, M.I.; de Jesus Ribeiro, C.M., and de Oliveira, T.R., 2019. Tannin as a new indicator of paleomangrove occurrence within an Amazonian coastal region. Journal of Coastal Research, 35(1), 82–90. Coconut Creek (Florida), ISSN 0749-0208.

This work aims to study the impacts of climate change in the subtropical mangroves during the late-Holocene on a southern Brazilian coastal plain and discuss the environmental conditions to the mangrove establishment near the austral limit of South America mangroves. Samples were collected to study palynological groups, sedimentary facies, and geochemistry analyses (δ¹³C, δ¹⁵N, TOC, TN, C:N ratio, TS, and C:S ratio), synchronized with four radiocarbon ages. The main result of this research was the mangrove succession, divided into three palynological zones composing two facies association: (1) herbaceous tidal flat and (2) mangrove tidal flat. The first zone between at least ~1815 and ~1629 cal. yr BP was marked by the mangrove absence with marine particulate organic carbon, C₃ terrestrial plants, and macrophytes organic matter influence with δ¹³C values between −26.7‰ and −20‰, δ¹⁵N values x̅ = 3.5‰ and C:N around 21.8. The second zone between ~1629 and ~853 cal. yr BP was marked by the mangrove establishment represented only by Laguncularia pollen under influence of estuarine organic matter (δ¹³C x̅ = −26.5‰; δ¹⁵N x̅ = 3.2‰, and C:N around 16.4). The third zone reveals an increase of Laguncularia and presence of Avicennia pollen since ~853 cal. yr BP. Near the surface (13C x̅ = −27.02‰; δ¹⁵N x̅ = 3.12‰, and C:N around 17.42). This mangrove vertical succession may be associated with the low-temperature tolerance, where the sequence Rhizophora, Avicennia, and Laguncularia occurs from the northern to the southern limits of Santa Catarina coast, respectively, reflecting the temperature gradient. Therefore, probably, the establishment of the mangrove assemblage identified along the studied pollen profile was influenced by a temperature increase of air and water during the late-Holocene and, considering the Rhizophora genus, only during the past decades.