Chitin determination on marine seston in a shallow temperate estuary (Argentina)

A quitina é um dos biopolímeros mais abundantes no planeta. A quitina foi quantificada em frações do seston, com a finalidade de obter a primeira caracterização deste polímero no Estuário de Bahía Blanca. A amostragem foi realizada durante o inverno e o verão em dois locais: em um canal de maré não impactado (Bahía del Medio, BM) e em um setor de descarga de esgoto (Canal Vieja, CV). Os maiores valores de quitina foram observados na fração seston ; 500 µM) não excederam ~ 1% de quitina total. A maior concentração de quitina no seston < 20 µM sugere que essa fração é um grande reservatório deste biopolímero, contribuindo para a matéria orgânica para os microorganismos na cadeia alimentar do Estuário de Bahía Blanca. Este é o primeiro estudo sobre as possíveis fontes de quitina em ecossistemas marinhos na Argentina.Chitin is one of the most abundant biopolymers in the planet. Chitin was quantified in seston fractions in order to obtain the first characterization of this polymer in the Bahía Blanca Estuary. Sampling was conducted at two sites: a non- impacted tidal channel -Bahía del Medio (BM)- and a sewage discharge sector -Canal Vieja (CV)-, during winter and summer. The highest values of chitin were observed in the seston fraction ;500 µm) did not exceed ~1% of total chitin.. The higher concentration of chitin in sesto

Overview of the comb jellies (Ctenophora) from the South-western Atlantic and Sub Antarctic region (32–60°S; 34–70°W)

Ctenophora are important components of marine ecosystems. However, the South-western Atlantic and Sub Antarctic region are still one of the least studied region in the world. We report the species composition and spatial distribution of Ctenophora and reviewed the studies performed in this region. New data obtained between 1910 and 2019, encompassing an area of c. 7 million km2 (32–60°S, 34–70°W) were presented and published information was added. We confirm the occurrence of nine taxa, seven of which have been previously reported in the region. Mnemiopsis leidyi and Pleurobrachia pileus were the most frequent and numerous species. Beroe ovata was frequently observed but reaching high numbers only occasionally. Beroe cucumis was always observed in low numbers. Callianira antarctica, Lampea pancerina and Mertensia ovum have been reported few times as single individuals. Eurhamphaea and Beroe sp. were found for the first time in the study region. This overview represents the state of the art in ctenophore research for the studied region, providing new knowledge on species composition and patterns of spatial distribution in the area.Fil: Schiariti, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Dutto, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Oliveira, Otto M.. Universidad Federal do Abc; BrasilFil: Faillia Siquier, Gabriela. Universidad de la República; UruguayFil: Puente Tapia, Francisco Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Chiaverano, Luciano. University of Mississippi; Estados Unido

Chitin determination on marine seston in a shallow temperate estuary (Argentina)

ABSTRACT Chitin is one of the most abundant biopolymers in the planet. Chitin was quantified in seston fractions in order to obtain the first characterization of this polymer in the Bahía Blanca Estuary. Sampling was conducted at two sites: a non- impacted tidal channel -Bahía del Medio (BM)- and a sewage discharge sector -Canal Vieja (CV)-, during winter and summer. The highest values of chitin were observed in the seston fraction 500 µm) did not exceed ~1% of total chitin.. The higher concentration of chitin in seston <20 µm suggests that this fraction is a large reservoir of this biopolymer contributing to organic matter for microorganisms in the food web of the Bahía Blanca Estuary. This study is also the first report on the possible sources of chitin in Argentina marine ecosystems

Microplankton dynamics under heavy anthropogenic pressure. The case of the Bahía Blanca Estuary, southwestern Atlantic Ocean

Quantifying biotic feedbacks in response to environmental signals is fundamental to assess ecosystem perturbation. We analyzed the joint effects of eutrophication, derived from sewage pollution, and climate at the base of the pelagic food web in the Bahía Blanca Estuary (SW Atlantic Ocean). A two-year survey of environmental conditions and microplankton communities was conducted in two sites affected by contrasting anthropogenic eutrophication conditions. Under severe eutrophication, we found higher phytoplankton abundance consistently dominated by smaller sized, non siliceous species, while microzooplankton abundance remained lower and nutrient stoichiometry showed conspicuous deviations from the Redfield ratio. Phytoplankton growth in such conditions appeared controlled by phosphorous. In turn, microplankton biomass and phytoplankton size ratio (20. μm) displayed a saturation relationship with nutrients in the highly eutrophic area, although mean phytoplankton growth was similar in both eutrophic systems. The strength of links within the estuarine network, quantified through path analysis, showed enhanced relationships under larger anthropogenic eutrophication, which fostered the climate influence on microplankton communities. Our results show conspicuous effects of severe sewage pollution on the ecological stoichiometry, i.e., N and P excess with respect to Si, altering nutrient ratios for microplankton communities. This warns on wide consequences on food web dynamics and ultimately in ecosystem assets of coastal pelagic environments

An overview of the Medusozoan from the Southwestern Atlantic

Medusozoans are critical components of coastal and marine ecosystems. They are ubiquitous, living from the surface to the bottom layers of the world’s oceans and tolerating a wide range of environmental conditions. They modulate food webs not only by consuming large quantities of ichthyoplankton and other zooplankton and acting as predators and competitors of varied pelagic organisms including fish but also by being consumed by other predators. Population outbreaks of these gelatinous animals commonly occur over a variety of spatiotemporal scales. These population explosion events have implications for the ecosystem and, usually, for human enterprise. Despite their ecological and socioeconomical importance, there is as yet no attempt to compile existing information on the medusozoan species of the Southwestern Atlantic (SWA). We provide here an overview of the information available regarding several aspects of Medusozoa in the SWA: the characteristics of their life cycles, life histories and “blooms,” and the ecological implications for SWA ecosystems. Guidelines for future research and perspectives on the field are also provided.Fil: Schiariti, Agustin. Instituto Nacional de Invest.y Desarr.pesquero. Proyecto Especies Costeras. Laboratorio de Zooplancton; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Dutto, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Carrara Morandini, André. Departamento de Zoologia, Instituto de Biociencias; BrasilFil: Nagata, Renato M.. Instituto de Oceanografia, Universidade Federal Do Rio; BrasilFil: Pereyra, Daiana Yanel. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Puente Tapia, Francisco Alejandro. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Cs.marinas. Estación "j.j.nagera" Grupo Medusas; ArgentinaFil: Diaz Briz, Luciana Mabel. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Cs.marinas. Estación "j.j.nagera" Grupo Medusas; ArgentinaFil: Genzano, Gabriel Nestor. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Cs.marinas. Estación "j.j.nagera" Grupo Medusas; Argentin

The role of the seasonal and semi-diurnal tidal cycle on mesozooplankton variability in a shallow mixed estuary (Bahía Blanca, Argentina)

The role of the seasonal and semi-diurnal tidal cycle on mesozooplankton dynamics was investigated in the inner zone of the Bahía Blanca Estuary (BBE), Argentina. Hydrological data and mesozooplankton samples were obtained bimonthly from December 2004 to April 2006, during 14 h tidal cycles. The mesozooplankton community was represented by 33 taxa. Taxa richness was greater near the bottom, where the contribution of benthic forms was notable. Abundances were greatest during summer (>5500 ind. m -3) and lowest during winter (<70 ind. m -3). The mesozooplankton community was dominated by Acartia tonsa and Eurytemora americana. Multivariate analyses revealed significant seasonal differences in community structure, especially in terms of density. Seasonal differences in community structure are well explained by the natural change of abiotic and biotic conditions, but temperature played a key role in structuring the mesozooplankton community. The zooplankton was significantly more abundant during the ebb, suggesting that local hydrological conditions are responsible for the spatial variations. The results demonstrate how variable the mesozooplankton community structure can be over different time-scales and provide a better understanding of zooplankton variability in the BBE and other temperate, turbid, mixed systems.Fil: Menendez, Maria Clara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Dutto, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Piccolo, Maria Cintia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin