Composition and community structure of mangroves distributed on the east coast of Marajó Island, Brazil

Mangroves in the Amazon are influenced by several environmental conditions that determine the composition and structural development of the arboreal flora, which results in different distribution patterns. In this study, we sought to answer two questions: (1) what is the composition and structure of the mangroves near the mouth of the Amazon River in Marajó Island? (2) Are the fringe and inland mangroves more similar or dissimilar in terms of floristic composition? For this, we delimited a fringe zone and an inland zone about 1 km apart from each other. In each zone, we distributed five 400-m2 plots. The individuals were grouped into diameter and height classes and structural and phytosociological parameters were calculated. Ten species were recorded in the mangroves, of which seven are typical of white-water (várzea) and black-water (igapó) flooded forest ecosystems. We believed the adjacent ecosystems and the hydrological network are inducing the establishment of such species. The composition and structure of mangroves did not differ statistically between zones, and the degree of similarity may be a result of similar environmental factors in these zones such as low relief and high frequency of macrotides. We conclude that the vegetation of the studied mangroves has a major influence of the fluvial-marine system of the great rivers of the Amazon associated with a diversity of ecosystems that, together, generate greater floristic richness when compared to mangroves in other regions.

Taxon-Specific Shifts in Bacterial and Archaeal Transcription of Dissolved Organic Matter Cycling Genes in a Stratified Fjord

It is generally recognized that stratification in the ocean strongly influences both the community composition and the distribution of ecological functions of microbial communities, which in turn are expected to shape the biogeochemical cycling of essential elements over depth. Here, we used metatranscriptomics analysis to infer molecular detail on the distribution of gene systems central to the utilization of organic matter in a stratified marine system.

Cost–benefit analysis of beach-cast harvest: Closing land-marine nutrient loops in the Baltic Sea region

Harvesting beach-cast can help mitigate marine eutrophication by closing land-marine nutrient loops and provide a blue biomass raw material for the bioeconomy. Cost–benefit analysis was applied to harvest activities during 2009–2018 on the island of Gotland in the Baltic Sea, highlighting benefits such as nutrient removal from the marine system and improved recreational opportunities as well as costs of using inputs necessary for harvest. The results indicate that the activities entailed a net gain to society, lending substance to continued funding for harvests on Gotland and assessments of upscaling of harvest activities to other areas in Sweden and elsewhere. The lessons learnt from the considerable harvest experience on Gotland should be utilized for developing concrete guidelines for carrying out sustainable harvest practice, paying due attention to local conditions but also to what can be generalized to a wider national and international context.

Sedimentological And Stratigraphical Analysis Of Kaki Bukit Formation (Lower Setul Member) At Teluk Ewa, Pulau Langkawi

The identification of new units on the carbonate sequence of Teluk Ewa (from Tg. Mendidih to Teluk Ewa) has given an idea for the review of stratigraphic succession of Kaki Bukit Formation (Lower Setul Member). The analysis is related to a sedimentology study, where the sedimentary sequences formed as a mixed siliciclastic–carbonate shallow marine system that combines the carbonate and silisiclastic deposits. Eight facies have been recognised such as (1) argillite facies, (2) interlayer of mudstone and limestone facies, (3) wavy stromatolites limestone facies, (4) linear stromatolites limestone facies, (5) heterolithic of mudstone-limestone facies, (6) shale facies, (7) massive limestone facies and (8) thrombolites limestone facies. Each facies are divided into four litostratigraphic units based on the evaluation from Malaysian Stratigraphic Nomenclature Committee (1997) and North American Stratigraphic Code 2005. (1) The clastic unit referring to the uppertmost part of Machinchang Formation maintains it's name. Meanwhile, the suggested nomenclature for the new units such as (2) The Sabung Member is referring to the basal carbonate unit comprising microbial facies and mixed silisiclastic-carbonate sediment. (3) The Pesak Seluar Member in the middle is a silisiclastic unit that consists of shale facies and (4) The Ewa Member at the top representing the upper limestone unit. All units show a similar litostratigraphic characteristics that are found in Tarutao Group, Pante Malaka Formation, Rung Nok Formation and Lae Tong Formation in Thailand as described by Wongwanich et al. (1990; 2002) and Imsamut & Abdul Rahman (2017).

Soil erosion, reservoir lake infill and coastal erosion in the Mediterranean coast of southern Spain.

The combination of vigorous terrain and millenary human action has produced major changes in vegetation cover, impacting soil losses from slopes and, consequently, sediment production. Increasing focus in the management of water resources led to the widespread construction of dams to generate water flows for iron production, irrigation and to satisfy the increasing demand of the massive urban development along the Costa del Sol. To investigate the connection between soil degradation and loss and river sediment transport retention at a major dam, a first-order sediment yield prediction was established by using a GIS-based model at river basin scale. A quantitative validation of model results is provided by empirical measurements of sedimentation in the main reservoir lake of La Concepción using D_GPS/Echo sounder combination and a Remotely Piloted Aircraft compared with pre-construction blue print topography aimed at documenting spot heights where sediments accumulated or eroded over 50 years. The significant erodibility that we have estimated seems matched by potentially high sediment accumulation rates along selected profiles and spot heights across the bottom of the reservoir lake. Our study discusses that Mediterranean coastal systems may no longer stay in the resilience envelope set by a critically delicate sediment transport balance and without engineering support in the form of direct sediment feeding to the marine system by the permanent nourishment works required. Due to soil loss, sediment entrapment in reservoirs and water management policies, the coastal protection offered by the natural resilience of the beach and dune system is no longer recoverable.

Lateral migration of large sedimentary bodies in a deep-marine system offshore of Argentina

Contourite features are increasingly identified in seismic data, but the mechanisms controlling their evolution remain poorly understood. Using 2D multichannel reflection seismic and well data, this study describes large Oligocene- to middle Miocene-aged sedimentary bodies that show prominent lateral migration along the base of the Argentine slope. These form part of a contourite depositional system with four morphological elements: a plastered drift, a contourite channel, an asymmetric mounded drift, and an erosive surface. The features appear within four seismic units (SU1–SU4) bounded by discontinuities. Their sedimentary stacking patterns indicate three evolutionary stages: an onset stage (I) (~ 34–25 Ma), a growth stage (II) (~ 25–14 Ma), and (III) a burial stage (< 14 Ma). The system reveals that lateral migration of large sedimentary bodies is not only confined to shallow or littoral marine environments and demonstrates how bottom currents and secondary oceanographic processes influence contourite morphologies. Two cores of a single water mass, in this case, the Antarctic Bottom Water and its upper interface, may drive upslope migration of asymmetric mounded drifts. Seismic images also show evidence of recirculating bottom currents which have modulated the system’s evolution. Elucidation of these novel processes will enhance basin analysis and palaeoceanographic reconstructions.

Piece-wise Linear Fuzzy Sliding Mode Controller for Deep Submergence Rescue Vehicle (DSRV)

The paper aims to present the design and performance of a single input fuzzy sliding mode controller (SIFSMC) to control the motion of deep submergence rescue vehicle (DSRV). The proposed controller uses the linear single dimension rule base where as the conventional fuzzy sliding mode controllers (CFSMC) uses the two-dimensional rule base. Moreover, the proposed controller does not merely depend on the DSRV exact mathematical model unlike that of the linear controllers. Using SIFSMC, the number of rules governs are also greatly reduced in comparison with the CFSMC, without compromising the overall performance. The robustness, equivalency and efficacy of proposed idea is illustrated through the simulation results using a marine system simulator in MATLAB/Simulink® environment. The main objective of the paper is to compare CFSMC and SIFSMC for UUV’s. Consequently, a comparative analysis of proposed SIFSMC is shown with the CFSMC for the same system of DSRV.

Potential Effects of Persistent Organic Contaminants on Marine Biota: A Review on Recent Research

Synthetic organic compounds belonging to different chemical classes and possessing diverse physicochemical properties are frequently present in marine environments. Microplastics, pharmaceuticals, pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) are contained in the list of persistent organic pollutants (POPs) that have been detected in the global marine system. Numerous ecotoxicological studies have revealed the direct and indirect effects of anthropogenic toxicants on marine biota. The present review presents the research that has been conducted during the period from 1 January 2016 to 30 June2021 concerning the lethal and sub-lethal impacts of selected organic-synthetic stressors on different plant and animal marine species, and summarizes the observed or predicted individual and combined effects after exposure to chemical mixtures of such contaminants. Future research needs dependent on the knowledge gaps that remain in the bibliography are also highlighted.