Distribution, abundance and assemblages of decapod crustaceans in waters off Guinea-Bissau (north-west Africa)

2011 ◽  
Vol 92 (3) ◽  
pp. 475-494 ◽  
Author(s):  
Isabel Muñoz ◽  
Eva García-Isarch ◽  
Ignacio Sobrino ◽  
Candelaria Burgos ◽  
Rita Funny ◽  
...  
Keyword(s):  
Sediment Type ◽  
Decapod Crustaceans ◽  
Depth Stratum ◽  
North West ◽  
Guinea Bissau ◽  
Future Assessment ◽  
New Information ◽  
Middle Slope ◽  
Coastal Shelf ◽  
Upper Slope

This study constitutes a first contribution to the knowledge of the ecology of the decapod crustaceans in waters off Guinea-Bissau. Samples were collected during a survey undertaken between October and November 2008. A total of 122 species of decapod crustaceans were identified. Results showed an increase of decapod biomass and abundance with depth, reaching maxima values in the 200–500 m depth stratum but decreasing at depths over 500 m. Average diversity by strata increased with depth, with maximum over the deep slope. Seven main assemblages were identified: five primarily associated with depth—coastal shelf (<60 m), shelf (60–200 m), upper slope (200–300 m), middle slope (300–500 m), deep slope (500–1000 m)—and two other northern shelf assemblages affected by sediment type—coastal shelf-north (<50 m) and shelf-north (50–100 m). Species of each assemblage are typified. This study provides new information about composition, distribution, abundance and assemblage structure of decapod crustaceans in Guinea-Bissau that may be useful for future assessment of the effect of trawling pressure in the area.

Decapod Crustaceans of the North West Shelf, a Tropical Continental Shelf of North-western Australia

1988 ◽  
Vol 39 (6) ◽  
pp. 751 ◽  
Author(s):  
T Ward ◽  
SF Rainer
Keyword(s):  
Continental Shelf ◽  
Decapod Crustacean ◽  
Common Species ◽  
Hermit Crabs ◽  
Sediment Type ◽  
Decapod Crustaceans ◽  
Crustacean Species ◽  
North West ◽  
The North ◽  
Sampling Times

The North West Shelf is a tropical continental shelf with a highly diverse fauna of epibenthic decapod crustaceans. The 357 taxa of epibenthic crustaceans, including 308 decapods, recorded from four sites are more than reported from any other continental shelf. The dominant taxa were amphipods, portunid crabs, xanthid crabs, palaemonid shrimps, hermit crabs, crangonid shrimps, sergestid shrimps, and majid crabs, in decreasing order of abundance. The most diverse family was the leucosiid crabs, containing 39 species. The number of crustacean species collected was similar at both 40 m and 80 m depth, and only 35% of the most common species differed in abundance between the depths. The abundances of 30% of these common species appeared to be related to particle size of the sediment or to the biomass of large sedentary fauna. The abundance of 45% of the most abundant, mainly small, species differed between two sampling times 6 months apart. The abundance of many decapod crustacean species was related to depth, sediment type, bottom type, or sedentary fauna. It is concluded that the epibenthic decapod fauna at 40 and 80 m depth on the North West Shelf is a broadly distributed assemblage with high diversity, some environmentally determined pattern and, in smaller animals, significant seasonal variability.

scholarly journals Assessment of the groundwater quantitative status in the Aosta Plain (North-West Italy): applicability of the national guidelines defined by ISPRA

2020 ◽  
Author(s):  
Gennaro A. Stefania ◽  
Michele Bigoni ◽  
Chiara Zanotti ◽  
Marco Rotiroti ◽  
Fulvio Simonetto ◽  
...  
Keyword(s):  
Monitoring Network ◽  
Water Bodies ◽  
National Guidelines ◽  
Groundwater Levels ◽  
North West ◽  
Future Assessment ◽  
Surface Water Bodies ◽  
Nw Italy ◽  
The Eu ◽  
Critical Aspects

The EU Water Framework Directive requires Member States to assess the quantitative and qualitative status of groundwater bodies and to achieve a good status by 2027. The present study was developed in order to assess the groundwater quantitative status in the Aosta Plain (NW Italy), following the methodology proposed through a guideline defined by the Italian Institute for Environmental Protection and Research (ISPRA), with the aim of supporting local authorities in their periodic assessment of water bodies status. In the study area, during the period 2000-2017, groundwater levels were measured in 213 wells and piezometers. Performing the four tests required by the abovementioned guideline, the quantitative status was assessed on the basis of multi-year groundwater level variations, water balance and the interconnections of groundwater with surface water bodies and groundwaterdependent ecosystems. A good status was assessed for the study area, although some critical aspects emerged from the application of the guideline methodology: the data collected by the monitoring network are not sufficiently robust in terms of sample size, spatial distribution, temporal interval and frequency to fulfill the requirements of the guideline methodology. Therefore, some recommendations to improve the data quality and better address the future assessment of groundwater quantitative status were given.

scholarly journals Demersal Assemblages on the Soft Bottoms off the Catalan-Levante Coast of the Spanish Mediterranean

2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
Mariano García-Rodríguez ◽  
Pere Abelló ◽  
Angel Fernández ◽  
Antonio Esteban
Keyword(s):  
Fisheries Management ◽  
Depth Distribution ◽  
Ecosystem Approach ◽  
Western Mediterranean ◽  
Multispecies Fisheries ◽  
Middle Slope ◽  
Soft Bottoms ◽  
High Species Richness ◽  
Total Species ◽  
Upper Slope

The analysis of 255 bottom trawl samples obtained in annual experimental surveys (2007–2010) along the western Mediterranean shows the existence of five well-defined demersal assemblages that follow a depth distribution: (a) upper shelf assemblages, including two assemblages differentiated by the type of substrate (sand-muddy and terrigenous muddy bottoms); (b) a middle shelf assemblage; (c) an upper slope assemblage; (d) a middle slope assemblage. Faunally, they are dominated by fish (37% of 452 total species), followed by crustaceans (22%), molluscs (17%), echinoderms (9%), and other invertebrates (15%). The assemblages identified showed major alterations on the shelf and shelf edge and less pronounced ones on the upper and middle slope. The average diversity values were more or less high, evidencing the high species richness in the western Mediterranean. The identified assemblages may facilitate future multispecies fisheries management based on an ecosystem approach.

Physico-chemical structure of the benthic environment of a Galician ría (Ría de Ares-Betanzos, north-west Spain)

1999 ◽  
Vol 79 (1) ◽  
pp. 1-21 ◽  
Author(s):  
A. Sánchez-Mata ◽  
M. Glémarec ◽  
J. Mora
Keyword(s):  
Organic Carbon ◽  
Principal Component ◽  
Clay Content ◽  
Size Composition ◽  
Total Carbon ◽  
Sediment Type ◽  
Overlying Water ◽  
Sediment Distribution ◽  
North West ◽  
Inorganic Content

In a preliminary study of the marine benthos of Ría de Ares-Betanzos, 50 stations covering the quadrant delineated by the coordinates 43°26′42″N–43°20′42″N and 08°18′54″W–08°10′12″W were sampled and sediment samples analysed for particle-size composition, sand, silt and clay content, degree of sorting, median diameter and grain-size diversity of sediments. Organic and inorganic content, total carbon and nitrogen, carbonates, organic carbon/total nitrogen ratio and bathymetric data were also collected. On a smaller scale a few stations were sampled for sediment redox potential and pH measurement. The salinity, temperature and oxygen content of the overlying water was also assessed.Cluster analysis and Principal Component Analysis methods were used to describe seabed heterogeneity and the pattern of sediment distribution within the ría, and to relate the environmental variables to each sediment type. Sediments were predominantly fine to very fine sands, and exhibited a direct depth-related gradient, i.e. with the finer grades, higher organic carbon and silt and clay occurring at the shallower areas of Pontedeume, Ares and Redes inlets and Ría de Betanzos sector where terrigenous input was important. Carbonate, organic carbon and organic matter maxima occurred in the central sector of the ría where most mollusc recruitment takes place: revealing the chiefly bioclastic origin of sediments. Taking into account the geological and hydrographic processes, explanations for the formation of the sedimentary bottoms in Ría de Ares-Betanzos are provided.

Sedimentary provinces, and associated bedforms and benthos on the Scott Reef-Rowley Shoals platform off north-west Australia

1988 ◽  
Vol 39 (2) ◽  
pp. 133 ◽  
Author(s):  
RJ McLoughlin ◽  
TLO Davis ◽  
TJ Ward
Keyword(s):  
Grain Size ◽  
Carbonate Content ◽  
Sediment Type ◽  
Sediment Grain Size ◽  
North West ◽  
Significant Relationships ◽  
Sediment Types ◽  
Sea Bed ◽  
Mean Grain Size ◽  
High Carbonate

The distribution of sediment types on the Scott Reef-Rowley Shoals platform, a marginal plateau adjoining the continental shelf of north-west Australia, has been investigated. Sediments in this region are predominately muds, with a high carbonate content. Sands, which are scarce, are mainly composed of both benthic and pelagic skeletal remains, with any gravel-sized material consisting of relict molluscan debris and, occasionally, relict coralline material. Correlation of sediment type with sea-bed characteristics as determined from photographs of the bottom at the same site showed significant relationships between mean grain size, and degree of sediment rippling and benthic activity. Similar correlations were found for the skewness measure of the analysis of sediment grain-size frequency. It is concluded that sediment type bears strong relationships with benthic activity and bedform morphology. Correlations between sediment provinces and the distribution of Australian scampi (Metanephrops sp.), a relatively new fishery in the region, are discussed.

Oceanographic scenario and fish larval distribution off Guinea-Bissau (north-west Africa)

2014 ◽  
Vol 95 (3) ◽  
pp. 435-452 ◽  
Author(s):  
M.P. Jiménez ◽  
R.F. Sánchez-Leal ◽  
C. González ◽  
E. García-Isarch ◽  
A. García
Keyword(s):  
Surface Waters ◽  
Larval Fish ◽  
Fish Larvae ◽  
Inner Shelf ◽  
North West ◽  
Guinea Bissau ◽  
Larval Distribution ◽  
Océanographic Survey ◽  
Continental Runoff ◽  
Abundance And Diversity

This paper describes the hydrography and the larval fish assemblage of Guinea Bissau waters, and analyses the spatial distribution of the main families in relation to the oceanographic features of the area. Data were obtained during an oceanographic survey, undertaken between October and November 2008. In addition to 98 demersal fishing hauls, a total of 33 stations, located between 20 and 1000 m depth, were sampled for hydrography and ichthyoplankton. Data showed that Guinea-Bissauan surface waters are characterized by a strong thermohaline front that flows parallel to the bathymetry of the area. Warm surface waters (SST > 29°C) occupy the inner shelf, and colder (SST < 26°C), chlorophyll-a-rich waters take over the shelf break. Continental runoff seems responsible for the low salinity of the inner-shelf waters whereas the colder types bear thermohaline features typical of tropical Atlantic waters. These features define a scenario which favours the development of fish early life stages, reflected in the high abundance and diversity of fish larvae recorded. A total of 84 taxa of fish larvae were identified. Only the family Clupeidae accounted for 54.8% of the sampled larvae. Other important families were Carangidae (8.8%), Sparidae (8.4%) and Myctophidae (5.9%).

scholarly journals Aspectos Pedogeomorfológicos e Mineralógicos de uma Topossequência de Solos Gnáissicos no Complexo Bação – Quadrilátero Ferrífero, MG, Brasil

2002 ◽  
Vol 29 (1) ◽  
pp. 71 ◽  
Author(s):  
MÚCIO DO AMARAL FIGUEIREDO ◽  
ANGÉLICA FORTES DRUMMOND CHICARINO VARAJÃO ◽  
JOSÉ DOMINGOS FABRIS ◽  
IVAN SOARES LOUTFI
Keyword(s):  
Mineralogical Composition ◽  
Minas Gerais ◽  
Mineralogical Association ◽  
Southern Area ◽  
Pedogenic Process ◽  
Quadrilátero Ferrífero ◽  
Middle Slope ◽  
Lower Slope ◽  
Primary Minerals ◽  
Upper Slope

The mineralogical association of the weathering rocks and their pedogenic process is fundamental in order to understand the erosive susceptibility of the soils. The regolith of the southern area of the Complexo Bação, Quadrilátero Ferrífero, Minas Gerais, was developed from gneiss and has as its predominant characteristic a thick saprolite (around 20 m) overlaid by a solum (A + B horizons) with of less than 3 m thick. This thickness is much thinner than those that frequently occur in the gneiss regolith from tropical and intertropical regions. In the toposequence investigated, the upper slope profile is a cambic soil with a poorly developed B horizon and with many relictal weathered gneiss nodules at the bottom, closer to the saprolite. The mineralogical composition of this B horizon is mainly kaolinite, gibbsite, quartz, hematite and goethite and secondarily pseudomorphous feldspars. The middle slope profile is a latosol with a well developed and thick B horizon. The mineralogical composition of this B horizon is essentially formed by kaolinite, gibbsite, quartz, hematite and goethite. The lower slope profile is a cambic latosol with the presence of relictal gneiss nodules in the B horizon analogously to the B horizon from the upper slope profile. Their mineralogical composition are also similar. The pedogeomorphological evolution of the studied catenary sequence shows that the middle slope profile is allochthonous with an accumulation of colluvial materials that formed a well developed latosol B horizon without primary minerals. The source of the colluvial materials is the upper slope profile. In the lower slope segment the lack of colluvial material suggests a process of incision, with channel and perennial flows that were originated from the adjacent gullies. The incipient fluvial plain that was formed occurs in abrupt altimetric unconformity (declivity rupture) with the lower slope segment.

A review of the Australian skate genus Pavoraja Whitley (Rajiformes: Arhynchobatidae)

Zootaxa ◽  
2008 ◽  
Vol 1812 (1) ◽  
pp. 1 ◽  
Author(s):  
PETER R. LAST ◽  
STEPHEN MALLICK ◽  
GORDON K. YEARSLEY
Keyword(s):  
New Species ◽  
Anatomical Structure ◽  
Colour Pattern ◽  
Nominal Species ◽  
Key To Species ◽  
Outer Continental Shelf ◽  
Additional Material ◽  
New Information ◽  
Species Pairs ◽  
Upper Slope

The Australian endemic skate genus Pavoraja Whitley, which contains six species including two valid nominal species (P. alleni and P. nitida) and four new species (P. arenaria sp. nov., P. mosaica sp. nov., P. pseudonitida sp. nov. and P. umbrosa sp. nov.), is redefined based on additional material. Members of the group occur primarily on the outer continental shelf and upper slope in both temperate and tropical Australian seas. The species are strongly partitioned geographically with smallto medium-scale ranges. Pavoraja arenaria is known to have a broad southern distribution but none is widespread in the Australian region. Only two species pairs, P. nitida and P. arenaria (off southern Australia), and P. mosaica and P. pseudonitida (off northeastern Australia), are known to be sympatric. New information is provided for the two nominal taxa, and the four new species are formally described and figured. Skeletal characteristics are described and illustrated, and a key to species is provided. Members of the genus differ primarily in colour pattern, squamation, morphometrics, meristics, and anatomical structure. The relationships of the genus Pavoraja to other arhynchobatid skates are discussed briefly.

Effect of Slope Positions and Years on Three Indexes to Artificial Ecological Substrate

2013 ◽  
Vol 773 ◽  
pp. 779-783
Author(s):  
Zhi Yu Hu ◽  
Huan Hu
Keyword(s):  
Organic Matter ◽  
Rock Slope ◽  
Unit Weight ◽  
Field Sampling ◽  
Natural Slope ◽  
Restoration Project ◽  
Middle Slope ◽  
Lower Slope ◽  
Water Ratio ◽  
Upper Slope

In the region of Hubei Shuibuya hydropower station, the paper studied the variation of slope positions and years to the artificial ecological substrate on Sanyouping highway rock slope by field sampling and office processing. The indexes which were measured and analyzed in experiment mainly included unit weight, water ratio and organic matter. The results showed that the distribution of the three indexes of artificial ecological substrate on the slope were different, and lacked rules to follow. The maximum of unit weight was the middle slope, and the maximum of water ratio was the lower slope, but the organic matter of upper slope was the maximum. As the implementation of ecological restoration project went on, the unit weight of artificial ecological substrate gradually reduced, and the content of organic matter steadily rose, but the water ratio was greatly affected by seasonal rainfall and fluctuated with years. Overall speaking, three kinds of indexes on the slope with the change of years gradually tended to the natural slope. It shows that the rock slope can be restored preferably as long as the ratio of artificial substrate is properly.

Demersal fish and decapod crustacean fauna of the upper continental slope off Nova Scotia from LaHave to St. Pierre Banks

1988 ◽  
Vol 66 (9) ◽  
pp. 1952-1960 ◽  
Author(s):  
Douglas F. Markle ◽  
Michael J. Dadswell ◽  
Ralph G. Halliday
Keyword(s):  
Nova Scotia ◽  
Transition Zone ◽  
Continental Slope ◽  
Decapod Crustacean ◽  
Fish Fauna ◽  
Demersal Fish ◽  
Depth Range ◽  
Decapod Crustaceans ◽  
Middle Atlantic ◽  
Upper Slope

Four 200-m depth strata were sampled for fish and decapod crustaceans on the upper continental slope (400–1200 m) off Nova Scotia. There was more-or-less continuous replacement of fish fauna with depth. Numerically dominant fishes in the upper two strata (< 800 m) were Sebastes spp., Phycis chesteri, and Glyptocephalus cynoglossus. Predominant fishes in the lower two strata (> 800 m) were Centroscyllium fabricii, Synaphobranchus kaupii, and Coryphaenoides rupestris. Nezumia bairdii was relatively abundant throughout the depth range sampled. The ichthyofauna of the upper slope was similar to that off the Middle Atlantic States and off Newfoundland at comparable depths, but qualitative differences existed in losses of some and additions of other species. Dominant decapod crustaceans in the shallowest stratum (200–400 m) were Pontophilus norvegicus, Plesiopenaeus edwardsianus, and Panalus propinquus. This stratum appeared to be a transition zone between shelf and slope decapod faunas. More species occurred and at higher densities in the deeper strata; predominant were Acanthephyra spp., Pasiphaea tarda, Metacrangon jacqueti, and Sabinea hystrix. The decapod fauna off Nova Scotia is similar to that of the mid-Atlantic Bight but less diverse.

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