Soft-Bottom macrobenthic communities of the Vitória Bay estuarine system, South-eastern Brazil

O presente trabalho analisa e descreve a estrutura das associações faunísticas macrobênticas (epifauna e infauna) do sistema estuarino da Baía de Vitória, sudeste do Brasil, de Janeiro de 1998 a Junho de 1999. Amostras replicadas em níveis de entre-marés e sublitoral foram coletadas em intervalos de três meses em dez estações. Foram caracterizadas as composições dos sedimentos de entre-marés e sublitoral. Os parâmetros físico-químicos da água foram medidos in situ. Foram coletados 10.695 indivíduos, compreendendo a 144 taxa. Os grupos mais abundantes foram moluscos, crustáceos e poliquetos. As espécies mais abundantes foram os bivalves Anomalocardia brasiliana, Mytella guyanensis e M. falcata. Localmente, descargas significativas de esgoto doméstico causaram um aumento da quantidade de matéria orgânica no sedimento (até 30%) e baixa concentração de oxigênio dissolvido na água (< 1mg.l-1). Próximo às duas entradas da baía, o alto hidrodinamismo e a presença de areia grossa reduziram os efeitos deletérios dos aportes de esgotos. A riqueza (S), a diversidade (H') de espécies e a abundância total (A), decresceram das estações externas do estuário (22 < S < 72; 1.99 < H' < 2.85; 320 < A < 1737) em direção às estações internas (2 < S < 45; 0.59 < H' < 2.67; 2 < A < 1317), onde a salinidade e oxigênio dissolvido foram menores e as quantidades de matéria orgânica maiores.The present work describes and analyses the structure of the macrobenthic epi- and infaunal assemblage of the estuarine system of Vitória Bay, South-eastern Brazil, from January 1998 to June 1999. Replicated sampling at intertidal and subtidal levels was conducted quarterly at ten stations. Intertidal and subtidal sediment composition was characterised. Water physico-chemical parameters were measured in situ. A total of 10,695 individuals, belonging to 144 taxa, were collected. Molluscs, crustaceans and polychaetes were the most abundant groups. The bivalves Anomalocardia brasiliana, Mytella guyanensis and M. falcata were the most abundant species. Locally, significant discharges of residential and industrial wastewater resulted in high organic content in the sediment (up to 30%) and low dissolved oxygen concentration in the water (< 1mg.l-1). Near the two entrances of the bay, high hydrodynamic activity and coarse sand reduced the detrimental effects of raw and treated sewage inputs. Species richness (S), diversity (H') and total abundance (A) decreased from outer-bay stations (22 < S < 72; 1.99 < H' < 2.85; 320 < A < 1737) towards inner-bay stations (2 < S < 45; 0.59 < H' < 2.67; 2 < A < 1317), where salinity and dissolved oxygen were lowest and organic matter content highest

Polychaete Invasion May Lead to Biogeochemical Change in Host Marine Environment

Marine invasive species may modify their host environment by altering ecosystem biogeochemistry. We hypothesized that the invasive polychaete Marenzelleria viridis in Baltic Sea areas increases sulfate reduction (SR) in sediment micro-zones surrounding its burrow. Consequently, higher free porewater sulfide (H2S) is expected in sediments dominated by M. viridis than in corresponding sediments inhabited by the native polychaete Hediste diversicolor. In a thin-aquaria experiment, we found high SR rates (220 to 539 nmol cm&minus;3 d&minus;1) around the burrow walls of M. viridis as well as in surface and subsurface sediments with overall rates 2-fold higher than in defaunated control sediment. Similarly, an in situ survey revealed subsurface porewater H2S peaks moving upward towards the sediment surface in M. viridis inhabited areas. Accordingly, 50&ndash;85% higher porewater H2S was found almost year-round in these areas compared with H. diversicolor inhabited areas, suggesting that the invasion of M. viridis probably led to a substantial change in sediment biogeochemistry. In conclusion, M. viridis stimulates SR in sediment micro-zones and increases H2S in coastal sediments. Such change to more reducing conditions after the invasion may have critical environmental implications on, e.g., the distribution of H2S intolerant flora and fauna species

Benthic responses to organic matter variation in a subtropical coastal area off SE Brazil

Organic matter quality, expressed as the proportion of chlorophyll a (Chl a) to degraded organic material (i.e. phaeopigments), is known to influence the structure of benthic associations and plays an important role in the functioning of the ecosystem. This study investigates the vertical distribution of microbial biomass, meiofauna and macrofauna with respect to organic matter variation in Ubatuba, Brazil, a southeastern, subtropical coastal area. On three occasions, samples were collected in exposed and sheltered stations, at high and low hydrodynamic conditions. We hypothesize that benthic assemblages will have high meio- and macrofaunal densities and high microbial biomass at the sediment surface at the sheltered site, and lower and vertically homogeneous microbial biomass and densities of meio- and macrofauna are expected at the exposed site. The accumulation of fresh organic matter at the sediment surface was observed at both stations over the three sampling dates, which contributed to the higher densities of meiofauna in the first layers of the sediment column. Macrofauna followed the same trend only at the exposed station, but changes in the number of species, biodiversity and feeding groups were registered for both stations. Microbial biomass increased at the sheltered station over the three sampling dates, whereas at the exposed station, microbial biomass was nearly constant. Physical exposure did not influence organic matter loading at the sites and therefore did not affect overall structure of benthic assemblages, which negates our original hypothesis. Most of the benthic system components reacted to organic matter quality and quantity, but relationships between different-sized organisms (i.e. competition and/or predation) may explain the unchanged microbial profiles at the exposed site and homogeneous vertical distribution of macrofauna at the sheltered site. In conclusion, the high quality of organic matter was a crucial factor in sustaining and regulating the benthic system, but coupled results showed that interactions between micro-, meio- and macrofauna can be highly complex.FUNDESPA (Fundacao de Pesquisas Aquaticas)FUNDESPA (Fundacao de Pesquisas Aquaticas)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)[01/00165-2

Benthic macrofauna bioturbation and early colonization in newly flooded coastal habitats.

How will coastal soils in areas newly flooded with seawater function as habitat for benthic marine organisms? This research question is highly relevant as global sea level rise and coastal realignment will cause flooding of soils and form new marine habitats. In this study, we tested experimentally the capacity of common marine polychaetes, Marenzelleria viridis, Nereis (Hediste) diversicolor and Scoloplos armiger to colonize and modify the biogeochemistry of the newly established Gyldensteen Coastal Lagoon, Denmark. All tested polychaetes survived relatively well (28-89%) and stimulated carbon dioxide release (TCO2) by 97-105% when transferred to newly flooded soils, suggesting that soil characteristics are modified rapidly by colonizing fauna. A field survey showed that the pioneering benthic community inside the lagoon was structurally different from the marine area outside the lagoon, and M. viridis and S. armiger were not among the early colonizers. These were instead N. diversicolor and Polydora cornuta with an abundance of 1603 and 540 ind m-2, respectively. Considering the species-specific effects of N. diversicolor on TCO2 release and its average abundance in the lagoon, we estimate that organic carbon degradation was increased by 219% in the first year of flooding. We therefore conclude that early colonizing polychaetes modify the soils and may play an important role in the ecological and successional developments, e.g. C cycling and biodiversity, in newly flooded coastal ecosystems. Newly flooded soils have thus a strong potential to develop into well-functioning marine ecosystems

Influence of benthic macrofauna community shifts on ecosystem functioning in shallow estuaries

We identify how ecosystem functioning in shallow estuaries is affected by shifts in benthic fauna communities. We use the shallow estuary, Odense Fjord, Denmark, as a case study to test our hypotheses that (1) shifts in benthic fauna composition and species functional traits affect biogeochemical cycling with cascading effects on ecological functioning, which may (2) modulate pelagic primary productivity with feedbacks to the benthic system. Odense Fjord is suitable because it experienced dramatic shifts in benthic fauna community structure from 1998 to 2008. We focused on infaunal species with emphasis on three dominating burrow-dwelling polychaetes: the native Nereis (Hediste) diversicolor and Arenicola marina, and the invasive Marenzelleria viridis. The impact of functional traits in the form of particle reworking and ventilation on biogeochemical cycles, i.e. sediment metabolism and nutrient dynamics, was determined from literature data. Historical records of summer nutrient levels in the water column of the inner Odense Fjord show elevated concentrations of NH4+ and NO3- (DIN) during the years 2004-2006, exactly when the N. diversicolor population declined and A. marina and M. viridis populations expanded dramatically. In support of our first hypothesis, we show that excess NH4+ delivery from the benthic system during the A. marina and M. viridis expansion period enriched the overlying water in DIN and stimulated phytoplankton concentration. The altered benthic-pelagic coupling and stimulated pelagic production may, in support of our second hypothesis, have feedback to the benthic system by changing the deposition of organic material. We therefore advice to identify the exact functional traits of the species involved in a community shift before studying its impact on ecosystem functioning. We also suggest studying benthic community shifts in shallow environments to obtain knowledge about the drivers and controls before exploring deep-water environments

Number and biomass (wet weight) of <i>Marenzelleria viridis</i> (<i>Mar</i>), <i>Nereis diversicolor</i> (<i>Ner</i>) and <i>Scoloplos armiger</i> (Sco) added to uncultivated (UC) and cultivated (C) soil cores.

<p>Recovery of polychaetes, maximum depth of burrows, area- and weight-specific bioirrigation rates for the three species of polychaetes observed by the end of the experiment.</p

Colonization of benthic infauna at the Western (W) and Eastern (E) stations after flooding of the Gyldensteen Coastal Lagoon.

<p>March 29, 2014 is point of origin for all graphs. X-axis tick marks indicate start of March (M), June (J), September (S) and December (D).</p

Sediment O₂ uptake (SOU) and exchange of TCO₂ and DIN in flooded uncultivated (UC) and cultivated (C) soil without (Con) and with added polychaetes (<i>Mar</i>: <i>Marenzelleria viridis</i>, <i>Ner</i>: <i>Nereis diversicolor</i> and <i>Sco</i>: <i>Scoloplos armiger</i>, respectively).

<p>Left and middle panels show temporal patterns and right panels show averages (from time of polychaete addition [t = 0] to end). Error bars indicate SE (n = 3). Capital and lower case letters in right panels represent the grouping of data obtained by 2-way ANOVA followed by Tukey post hoc analysis. Capital letters indicate significant difference between UC and C. Lower case letters indicate significant difference between core treatments (Con, <i>Mar</i>, <i>Ner</i> and <i>Sco</i>). * indicates significant interaction between the factors soil type and core treatment.</p

Flux increase (%) for treatments with polychaetes added (<i>Mar</i>: <i>Marenzelleria viridis</i>, <i>Ner</i>: <i>Nereis diversicolor</i> and <i>Sco</i>: <i>Scoloplos armiger</i>) in relation to defaunated controls (Con).

<p>Flux increase (%) for treatments with polychaetes added (<i>Mar</i>: <i>Marenzelleria viridis</i>, <i>Ner</i>: <i>Nereis diversicolor</i> and <i>Sco</i>: <i>Scoloplos armiger</i>) in relation to defaunated controls (Con).</p