Taxonomic sufficiency of polychaete taxocenes for estuary monitoring (original) (raw)
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Polychaete assemblage of an impacted estuary, Guanabara Bay, Rio de Janeiro, Brazil
2009
Avenida Nazaré, 481, 04263-000, São Paulo, SP, Brasil) mdst@usp.br A B S T R A C T Thirty-eight stations were sampled in Guanabara Bay, Rio de Janeiro, Brazil, to assess the spatio-temporal diversity and biomass of sublittoral polychaetes. Samples were collected during the dry (September 2000) and rainy season (May 2001) in shallow sublittoral sediments. The polychaete spatial composition showed a heterogeneous distribution throughout the bay. A negative gradient of diversity and biomass was observed towards the inner parts of the bay and sheltered areas. A wide azoic area was found inside the bay. Some high-biomass and low-diversity spots were found near a sewage-discharge point. In these areas, the polychaete biomass increased after the rainy season. A diversified polychaete community was identified around the bay mouth, with no dramatic changes of this pattern between the two sampling periods. Deposit-feeders were dominant in the entire study area. The relative importance of carnivores and omnivores increased towards the outer sector, at stations with coarse sediment fractions. Guanabara Bay can be divided into three main zones with respect to environmental conditions and polychaete diversity and biomass patterns: A) High polychaete diversity, hydrodynamically exposed areas composed of sandy, oxidized or moderately reduced sediments with normoxic conditions in the water column. B) Low diversity and high biomass of deposit and suspension-feeding polychaete species in the middle part of the bay near continental inflows, comprising stations sharing similar proportions of silt, clay and fine sands. C) Azoic area or an impoverished polychaete community in hydrodynamically low-energy areas of silt and clay with extremely reduced sediments, high total organic matter content and hypoxic conditions in the water column, located essentially from the mid-bay towards the north sector. High total organic matter content and hypoxic conditions combined with slow water renewal in the inner bay seemed to play a key role in the polychaete diversity and biomass. Sedimentation processes and organic load coming from untreated sewage into the bay may have negatively affected the survivorship of the fauna.
Journal of Coastal Research, 2006
The Guanabara Bay measures 384 Km and a large portion of the largely untreated domestic sewage from at least 7,81 million people eventually ends up in its waters. About 12000 industries are located on its drainage basin. The ongoing pressure upon the Bay requires an updated knowledge of its ecosystems structure and function. Patterns of species richness and species densities for the polychaete taxocenosis in the Bay were assessed through a sampling design consisting of 38 stations performed during the dry (September, 2000) and the rainy seasons (May, 2001). Surface and bottom water characteristics were recorded for each sampling site. Sediment was obtained in triplicate with a 0,1m Van-Veen grab and analyzed by its sedimentological features such as: grain size, organic matter content, carbonates, and redox potential. Independent of the season studied, the sediment becomes more anoxic while the organic matter content greatly increases towards the inner parts of the Bay. The BIOENV-revealed that the organic matter content, sorting coefficient, dissolved oxygen concentration, and redox potential characterized a number of sample stations sharing similar hydrodynamic environments. The samples yielded 72 species of polychaetes totaling 9021 individuals. The species richness proved to diminish dramatically towards the inner parts of the Bay. The higher species richness in the outer parts of the Bay could be related to better environmental conditions and its more hydrodynamic environment. Three species of polychaetes accounted for 79,93% of the total species density. Densities were generally much higher nearby the wastewater flow. 2 2 test Domestic sewage, coastal management, environmental impact ADDITIONAL INDEX WORDS: . ABSTRACT
Taxonomic sufficiency as a useful tool for typology in a poikilohaline estuary
Hydrobiologia, 2007
Taxonomic sufficiency has been used mainly to assess benthic condition, based on the assumption that taxa can be identified to a taxonomic level higher than the species level without losing the ability to detect changes related to pollution stress. Identifying taxa to a higher level reduces the expertise and time needed to identify organisms and consequently allows increased spatial and temporal replication. The usefulness of taxonomic sufficiency for typology (identification of water body types) was examined using the benthic communities of the Mondego River estuary (Portugal). Benthic samples were collected seasonally along the Northern branch of the Mondego River estuary from July 2000 to June 2001 and several environmental parameters were measured simultaneously. Cluster analysis of species data indicated three major ecological groups, mainly related to a saline gradient along the estuary. The same groups were found when taxa were aggregated to higher taxonomic levels (genus, family, order, class), except for the phylum level. The overall spatial pattern was driven by: (1) the dominance of bivalves and the occurrence of rare marine species in the Lower Estuary; (2) the dominance of polychaetes in the Middle Estuary; (3) and the dominance of arthropods in the Upper Estuary. The ability of different taxocenes to discriminate the three ecological groups was also examined. Mollusca and Bivalvia were the only taxocenes producing the same groupings, although other taxocenes (Annelida, Polychaeta, Spionidae, Arthropoda) showed a significant ability to discriminate between all three groups. Compared to using all taxa identified to the lowest possible taxonomic level, our results indicate that for typology (1) several higher taxonomic levels were sufficient (2) while few taxocenes alone were sufficient.
Benthic polychaetes in the Ratnagiri bay, India : Influence of anthropogenic factors Author Details
Study of changes in macrobenthic community structure is an intrinsic part of many environmental monitoring programmes. Hence, it is pivotal to distinguish the effects of natural and anthropogenic factors on these sensitive organisms for accurate assessment and management of coastal environment. Polychaete species diversity of five stations in the Ratnagiri bay was investigated during premonsoon and postmonsoon months in 2007. Though no spatial trends in polychaete diversity vis-à-vis the pollution was visible, the polychaete univariate indices were uniformily better in premonsoon indicating clear seasonal trends. Shannon diversity values ranged from 1.4-2.4 during premonsoon and 0.6-1.6 during postmonsoon. Station 5, which was most impacted by anthropogenic wastes as demonstrated by the anoxic conditions coupled with higher nutrient load, had comparatively higher H' values (1.9 and 1.6) and better evenness values (0.9 and 0.7) during both seasons indicating that the polychaetes were not influenced by anthropogenic contamination. The study indicates that the polychaete distribution and diversity in the bay were governed primarily by variations in sediment texture rather than the anthropogenic disturbances.
Benthic polychaetes in the Ratnagiri bay, India: influence of anthropogenic factors
Journal of environmental biology / Academy of Environmental Biology, India, 2011
Study of changes in macrobenthic community structure is an intrinsic part of many environmental monitoring programmes. Hence, it is pivotal to distinguish the effects of natural and anthropogenic factors on these sensitive organisms for accurate assessment and management of coastal environment. Polychaete species diversity of five stations in the Ratnagiri bay was investigated during premonsoon and postmonsoon months in 2007. Though no spatial trends in polychaete diversity vis-à-vis the pollution was visible, the polychaete univariate indices were uniformily better in premonsoon indicating clear seasonal trends. Shannon diversity values ranged from 1.4-2.4 during premonsoon and 0.6-1.6 during postmonsoon. Station 5, which was most impacted by anthropogenic wastes as demonstrated by the anoxic conditions coupled with higher nutrient load, had comparatively higher H' values (1.9 and 1.6) and better evenness values (0.9 and 0.7) during both seasons indicating that the polychaetes ...
Are Benthic Polychaetes in the Ratnagiri Bay , India influenced by anthropogenic factors ?
2011
Study of changes in macrobenthic community structure is an intrinsic part of many environmental monitoring programmes. Hence it is pivotal to distinguish the effects of natural and anthropogenic factors on these sensitive organisms for accurate assessment and management of coastal environment. Polychaete species diversity of five stations in the Ratnagiri bay was investigated during premonsoon and postmonsoon months in 2007. Though no spatial trends in polychaete diversity vis-à-vis the pollution was visible, the polychaete univariate indices were uniformily better in premonsoon indicating clear seasonal trends. Shannon diversity values ranged from 1.4-2.4 during premonsoon and 0.6-1.6 during postmonsoon. Station 5, which was most impacted by anthropogenic wastes as demonstrated by the anoxic conditions coupled with higher nutrient load, had comparatively higher H’ values (1.9 and 1.6) and better evenness values (0.9 and 0.7) during both seasons indicating that the polychaetes were ...
Polychaete Distribution and Abundance in Intertidal Flats of Paranaguá Bay (SE Brazil)
Bulletin of Marine Science -Miami-
The effects of plant zonation on polychaete distribution and abundance were studied along an environmental gradient in intertidal flats of Paranaguá Bay (SE Brazil). Two polychaete stocks with marked preference for specific haline regimes were recognized with a low degree of spatial overlap in species distribution. Species richness and abundance were lower in the mesohaline sector, characterized by fine sediments and high organic carbon content, than in the high-energy euhaline sector, dominated by moderately sorted fine sands low in organic carbon content. Faunal differences were primarily defined by salinity and environmental energy gradients and only secondarily by the ability of polychaetes to discriminate among unvegetated, salt marsh or mangrove swamp habitats.