A Pilot Study for the Estimation of Above Ground Biomass and Litter Production in Rhizophora Mucronata Dominated Mangrove Ecosystems in the Island of Mauritius

Estimation of the above ground biomass of mangroves is an important issue because of its relevance to nutrient turnover and the potential to store carbon. Productivity, as indicated by litter fall rates is important to determine the rate at which mangroves produce new biomass. The aim of the current study was to estimate the above ground biomass and quantify litter fall in two Rhizophora mucronata dominated mangrove ecosystems of Mauritius located at Trou D'eau Douce (eastern side), and at Petite Riviere Noire on the (western side) of the island. Field studies were conducted from September 2011 to January 2012. Quadrats of 5 × 5 metres were set up in each site and 200 mature trees were surveyed. Sixteen litter traps were constructed and installed at the two sites for litter collection. To estimate the above ground biomass, allometric equations were used. The total above ground biomass for Trou D'eau Douce and Petite Riviere Noire were 26.96 t ha-1 and 16.63 t ha-1, respectively. The mean rate of litter fall for Trou D'eau Douce and Petite Riviere Noire were 3.2 ± 0.44 g DW m-2 day-1 and 4.07± 0.95 g DW m-2 day-1, respectively. This study is among the first to provide information on the estimation of above ground biomass for mangroves of Mauritius. It is also the first to provide data on the litter production in mangroves at Petite Riviere Noire and Trou D'eau Douce

A Preliminary Study on Benthic and Arboreal Fauna Associated with Mangrove Rhizophora Mucronata on the East Coast of Mauritius (Indian Ocean) with Special Reference to the Mollusca

Mangrove ecosystems are important as they harbour a diversity of life forms. This study aimed at studying the benthic and arboreal macrofaunal diversity and abundance associated with three naturally occurring mangrove forests of Mauritius, Western Indian Ocean. The mangrove areas included Roches Noires, Mahebourg and Pointe Maurice, on the east coast of the island. The field study was carried out at low tide during summer season from October 2003 to February 2004. At each of the three sites, the arboreal and benthic macrofauna were sampled separately, using quadrats of 1 m x 1 m and 25 cm x 25 cm, respectively. Sixty-four benthic and 42 arboreal quadrats were collected from Roche Noires, 40 benthic and 41 arboreal quadrats at Mahebourg and 40 benthic and 30 arboreal quadrats at Pointe Maurice. The results showed that benthic habitat is more diverse with regards to molluscan families (24 families) than the arboreal habitat (5 families). Pointe Maurice has a more diverse benthic fauna. Relative percentage abundance and mean density of molluscan families are reported. Highest mean densities and relative abundance were recorded for the Family Littorinidae among arboreal macrofauna. In benthic macrofauna, the highest mean densities and relative abundance were noted in Family Cerithiidae at Roches Noires and Mahebourg

A Study on Assemblage of Invertebrates Inhabiting Rocky Shores Within the Port- Limit of Port- Louis, Mauritius

Rocky shores provide an important habitat for marine organisms. This study aimed at providing baseline data on assemblage of organisms on rocky shores within the port-limit of Port-Louis, Mauritius. Four rocky shores, with three at Pointe aux Sables (La Pointe1, La Pointe2, and Petit Verger) and one at Baie du Tombeau were studied from October 2007 to February 2008. On each site three stations, located at intervals of 2m, with an area of 40m2 each were set up. Intertidal organisms were hand-collected within forty-eight, 1m2 quadrat for invertebrates. Observations of 16,061 specimens led to identification of 30 faunal species belonging mostly to phyla Mollusca and Arthropoda. Mean total abundance of invertebrates per 1m2 varied from 729.22±173.07 at la Pointe2 to 143.97±11.43 at Baie du Tombeau. The gastropod, Planaxis sulcatus was the most abundant species at La Pointe1 and Petit Verger with mean abundance of 196.86±179.71 and 168.10±113.44 per 1m2 respectively. The bivalve, Modiolus auriculatus was the dominant species with mean abundance of 673.33±762.04 per 1m2 at La Pointe2 and Nerita punctata was most abundant (39.41±57.35 per 1m2) at Baie du Tombeau. Lowest Shannon diversity was observed La Pointe 2. The study is useful for future work on port area

An Analysis of Zooplankton Fauna Associated with Mangrove and Non-Mangrove Ecosystems in Mauritius

Zooplankton are important components of marine food webs, yet very few studies exist on the mangrove plankton of Mauritius. The aim of this study was to analyze the zooplankton fauna and to assess differences between mangrove and non-mangrove ecosystems. Two mangrove ecosystems (Pointe D’Esny and Ferney) and one non-mangrove ecosystem (Bois des Amourettes) were studied for zooplankton abundance, diversity and community structure along the southeast coast of Mauritius. The study was conducted from October to December 2012 and plankton samples were collected using standard plankton nets. Zooplankton fauna of the three ecosystems were representative of the Phyla Arthropoda, Sarcomastigophora, Mollusca, Nematoda, Annelida, Chaetognatha and Ctenophora. Copepods formed the bulk of the zooplankton community (66.44% in Pointe D’Esny mangrove ecosystem and 36.43% in the nonmangrove ecosystem). Cyclopoid Oithona was the most abundant zooplankton in the two mangrove ecosystems with densities of 964 Organisms m-3 and 7760 Organisms m-3 while Foraminiferan Globigerina (329 Organisms m-3) was the most abundant organism in the non-mangrove one. Mangrove sites were found to be more diverse (Margaleff’s Diversity Index: 1.71 and 1.41) in zooplankton than non-mangrove site (Margaleff’s Diversity Index: 1.27). This study supports the view that mangrove ecosystems are a rich habitat and nursery ground.Keywords: Zooplankton, Abundance, Diversity, Mangrove, Copepods, Cyclopoid Oithon

HI Selected Galaxies in the Sloan Digital Sky Survey I: Optical Data

We present the optical data for 195 HI-selected galaxies that fall within both the Sloan Digital Sky Survey (SDSS) and the Parkes Equatorial Survey (ES). The photometric quantities have been independently recomputed for our sample using a new photometric pipeline optimized for large galaxies, thus correcting for SDSS's limited reliability for automatic photometry of angularly large or low surface brightness (LSB) galaxies. We outline the magnitude of the uncertainty in the SDSS catalog-level photometry and derive a quantitative method for correcting the over-sky subtraction in the SDSS photometric pipeline. The main thrust of this paper is to present the ES/SDSS sample and discuss the methods behind the improved photometry, which will be used in future scientific analysis. We present the overall optical properties of the sample and briefly compare to a volume-limited, optically-selected sample. Compared to the optically-selected SDSS sample (in the similar volume), HI-selected galaxies are bluer and more luminous (fewer dwarf ellipticals and more star formation). However, compared to typical SDSS galaxy studies, which have their own selection effects, our sample is bluer, fainter and less massive.Comment: 14 pages, 8 Figures, accepted for publication in AJ. Complete tables will be available in the AJ electronic version and on the Vizier sit

The far-infrared view of M87 as seen by the Herschel Space Observatory

The origin of the far-infrared emission from the nearby radio galaxy M87 remains a matter of debate. Some studies find evidence of a far-infrared excess due to thermal dust emission, whereas others propose that the far-infrared emission can be explained by synchrotron emission without the need for an additional dust emission component. We observed M87 with PACS and SPIRE as part of the Herschel Virgo Cluster Survey (HeViCS). We compare the new Herschel data with a synchrotron model based on infrared, submm and radio data to investigate the origin of the far-infrared emission. We find that both the integrated SED and the Herschel surface brightness maps are adequately explained by synchrotron emission. At odds with previous claims, we find no evidence of a diffuse dust component in M87.Comment: 4 pages, 2 figures, proceedings IAU Symposium 275 (Jets at all scales

The Herschel Virgo Cluster Survey: I. Luminosity functions

We describe the Herschel Virgo Cluster Survey (HeViCS) and the first data obtained as part of the Science Demonstration Phase (SDP). The data cover a central 4x4 sq deg region of the cluster. We use SPIRE and PACS photometry data to produce 100, 160, 250, 350 and 500 micron luminosity functions (LFs) for optically bright galaxies that are selected at 500 micron and detected in all bands. We compare these LFs with those previously derived using IRAS, BLAST and Herschel-ATLAS data. The Virgo Cluster LFs do not have the large numbers of faint galaxies or examples of very luminous galaxies seen previously in surveys covering less dense environments.Comment: Letter accepted for publication in A&A (Herschel special issue

The Herschel Virgo Cluster Survey: II. Truncated dust disks in HI-deficient spirals

By combining Herschel-SPIRE observations obtained as part of the Herschel Virgo Cluster Survey with 21 cm HI data from the literature, we investigate the role of the cluster environment on the dust content of Virgo spiral galaxies.We show for the first time that the extent of the dust disk is significantly reduced in HI-deficient galaxies, following remarkably well the observed 'truncation' of the HI disk. The ratio of the submillimetre-to- optical diameter correlates with the HI-deficiency, suggesting that the cluster environment is able to strip dust as well as gas. These results provide important insights not only into the evolution of cluster galaxies but also into the metal enrichment of the intra-cluster medium.Comment: Letter accepted for publication in A&A (Herschel special issue

The Herschel Virgo cluster survey: V. Star-forming dwarf galaxies - dust in metal-poor environments

We present the dust properties of a small sample of Virgo cluster dwarf galaxies drawn from the science demonstration phase data set of the Herschel Virgo Cluster Survey. These galaxies have low metallicities (7.8 < 12 + log(O/H) < 8.3) and star-formation rates < 10^{-1} M_{sun}/yr. We measure the spectral energy distribution (SED) from 100 to 500 um and derive dust temperatures and dust masses. The SEDs are fitted by a cool component of temperature T < 20 K, implying dust masses around 10^{5} M_{sun} and dust-to-gas ratios D within the range 10^{-3}-10^{-2}. The completion of the full survey will yield a larger set of galaxies, which will provide more stringent constraints on the dust content of star-forming dwarf galaxies.Comment: Letter accepted for publication in A&A (Herschel special issue

ALMA Long Baseline Observations of the Strongly Lensed Submillimeter Galaxy HATLAS J090311.6+003906 at z=3.042

We present initial results of very high resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the $z$=3.042 gravitationally lensed galaxy HATLAS J090311.6+003906 (SDP.81). These observations were carried out using a very extended configuration as part of Science Verification for the 2014 ALMA Long Baseline Campaign, with baselines of up to 15 km. We present continuum imaging at 151, 236 and 290 GHz, at unprecedented angular resolutions as fine as 23 milliarcseconds (mas), corresponding to an un-magnified spatial scale of ~180 pc at z=3.042. The ALMA images clearly show two main gravitational arc components of an Einstein ring, with emission tracing a radius of ~1.5". We also present imaging of CO(10-9), CO(8-7), CO(5-4) and H2O line emission. The CO emission, at an angular resolution of ~170 mas, is found to broadly trace the gravitational arc structures but with differing morphologies between the CO transitions and compared to the dust continuum. Our detection of H2O line emission, using only the shortest baselines, provides the most resolved detection to date of thermal H2O emission in an extragalactic source. The ALMA continuum and spectral line fluxes are consistent with previous Plateau de Bure Interferometer and Submillimeter Array observations despite the impressive increase in angular resolution. Finally, we detect weak unresolved continuum emission from a position that is spatially coincident with the center of the lens, with a spectral index that is consistent with emission from the core of the foreground lensing galaxy.Comment: 9 pages, 5 figures and 3 tables, accepted for publication in the Astrophysical Journal Letter