Coupling between microbial assemblages and environmental drivers along a tropical estuarine gradient.

The change in the community structure of phytoplankton and bacterioplankton, and in the degree of coupling between them as well as the environmental conditions, have substantial impacts on the transfer of energy to higher trophic levels and finally on the fate of organic matter. The microbial community structure, usually described only by the abundance of the different taxonomic or functional groups, can be extended to include other levels of descriptors, like physiological state and single-cell properties. These features play a role in the ecological regulation of microbial communities but are not generally studied as additional descriptors of the community structure.

Niche selection in bacterioplankton: A study of taxonomic composition and single-cell characteristics in an acidic reservoir.

Niche selection and microbial dispersal are key factors that shape microbial communities. However, their relative significance varies across different environments and spatiotemporal scales. While most studies focus on the impact of these forces on community composition, few consider other structural levels such as the physiological stage of the microbial community and single-cell characteristics.

Trophic status of a coastal lagoon - marine harbor system: Potential outwelling rates to the Mesoamerican Barrier Reef southern region.

Eutrophication is still a serious problem in many coastal areas, including the tropics, where river discharges of nutrients is usually high. The ecological stability and ecosystem services of the Mesoamerican Barrier Reef System (MBRS), the world's second-largest coral reef system, suffer a generalized impact by riverine discharge of sediment and organic and inorganic nutrients, which may lead to coastal eutrophication and a coral-macroalgal phase shift. However, few data exist on the MRBS coastal zone status, particularly in Honduras.

Seasonal cycles of phytoplankton biomass and primary production in a tropical temporarily open-closed estuarine lagoon - The effect of an extreme climatic event.

Temporarily open-closed estuaries and estuarine lagoons are among the most complex aquatic ecosystems, prone to undergo rapid changes in response to global change and other anthropogenic impacts. Nonetheless, studies on the factors that control annual cycles of phytoplanktonic biomass and primary production in such systems, especially tropical ones, are still scarce. Even less information exists on the effect increasingly frequent extreme climatic events (ECE) might have on their dynamics.

Tidal elevation is the key factor modulating burial rates and composition of organic matter in a coastal wetland with multiple habitats.

This study examines long-term burial rates of organic carbon (OC), organic nitrogen (ON), and total sulphur (TS) in a tidal-dominated coastal wetland with a high spatial heterogeneity and habitat diversity, and long history of human impacts, Cádiz Bay (SW Spain). Using replicate sediment cores, we quantified fluxes of these elements over a transect, extending from the lower saltmarsh (Spartina maritima, ~0.3 m mean sea level, MSL) to the lower intertidal region (Zostera noltei, ~ - 0.

Water column dissolved silica concentration limits microphytobenthic primary production in intertidal sediments.

Primary production of microphytobenthos (MPB) contributes significantly to the total production in shallow coastal environments. MPB is a diverse community in which diatoms are usually the main microalgal group. Diatoms require N, P, and other nutrients as with other autotrophs, but in addition require silicate to create their outer cell wall.

Different Types of Diatom-Derived Extracellular Polymeric Substances Drive Changes in Heterotrophic Bacterial Communities from Intertidal Sediments.

Intertidal areas support extensive diatom-rich biofilms. Such microphytobenthic (MPB) diatoms exude large quantities of extracellular polymeric substances (EPS) comprising polysaccharides, glycoproteins and other biopolymers, which represent a substantial carbon pool. However, degradation rates of different EPS components, and how they shape heterotrophic communities in sediments, are not well understood.

Dynamics of Inorganic Nutrients in Intertidal Sediments: Porewater, Exchangeable, and Intracellular Pools.

The study of inorganic nutrients dynamics in shallow sediments usually focuses on two main pools: porewater (PW) nutrients and exchangeable (EX) ammonium and phosphate. Recently, it has been found that microphytobenthos (MPB) and other microorganisms can accumulate large amounts of nutrients intracellularly (IC), highlighting the biogeochemical importance of this nutrient pool. Storing nutrients could support the growth of autotrophs when nutrients are not available, and could also provide alternative electron acceptors for dissimilatory processes such as nitrate reduction.

Kinetics of Indigenous Nitrate Reducing Sulfide Oxidizing Activity in Microaerophilic Wastewater Biofilms.

Nitrate decreases sulfide release in wastewater treatment plants (WWTP), but little is known on how it affects the microzonation and kinetics of related microbial processes within the biofilm. The effect of nitrate addition on these properties for sulfate reduction, sulfide oxidation, and oxygen respiration were studied with the use of microelectrodes in microaerophilic wastewater biofilms. Mass balance calaculations and community composition analysis were also performed.

Photosynthetic activity and community shifts of microphytobenthos covered by green macroalgae.

Macroalgae blooms, a frequent consequence of eutrophication in coastal areas, affect the photosynthetic activity of sediments dominated by microphytobenthos (MPB). Light spectra, steady-state (after 1 h) microprofiles of O2 , gross photosynthesis (Pg ), community respiration in light (RL ) and net community photosynthesis (Pn ) were measured in diatom- and cyanobacteria-dominated communities below increasing layers of Ulva. Photosynthetic photon flux (PPF) decreased exponentially with increasing layers of algae and the light spectrum was increasingly enriched in the green and deprived in blue and red regions.

Nitrate stimulation of indigenous nitrate-reducing, sulfide-oxidising bacterial community in wastewater anaerobic biofilms.

The role of the nitrate-reducing, sulfide-oxidising bacteria (NR-SOB) in the nitrate-mediated inhibition of sulfide net production by anaerobic wastewater biofilms was analyzed in two experimental bioreactors, continuously fed with the primary effluent of a wastewater treatment plant, one used as control (BRC) and the other one supplemented with nitrate (BRN). This study integrated information from H(2)S and pH microelectrodes, RNA-based molecular techniques, and the time course of biofilm growth and bioreactors water phase. Biofilms were a net source of sulfide for the water phase (2.

Nitrate promotes biological oxidation of sulfide in wastewaters: experiment at plant-scale.

Biogenic production of sulfide in wastewater treatment plants involves odors, toxicity and corrosion problems. The production of sulfide is a consequence of bacterial activity, mainly sulfate-reducing bacteria (SRB). To prevent this production, the efficiency of nitrate addition to wastewater was tested at plant-scale by dosing concentrated calcium nitrate (Nutriox) in the works inlet.