Faculty Opinions recommendation of An extensive reef system at the Amazon River mouth.

The Amazon region contains a great diversity of species, and the Amazon River basin accounts for almost 20% of all the freshwater in the world. Despite the favorable environmental conditions in this region, little is known about the cyanobacterial diversity of this waterbody, especially at the mouth of the river. In this paper, we used the polyphasic approach to identify 14 cyanobacterial strains isolated in the Amazon River on the inlet site from a drinking water supply located close to the river mouth. The isolated strains were characterized based on morphology, behavior in culture, 16S rRNA gene sequencing, phylogenetic analysis and potential for toxin production. The isolated strains belong to seven different genera, namely, Alkalinema, Cephalothrix, Limnothrix, Leptolyngbya, Phormidium, Pseudanabaena and an unidentified Nostocales taxa that may represent a new genus. Strikingly, there were no new species, nor detection of gene clusters associated with cyanotoxin production. However, the phylogenetic placements of the Amazonian strains of Limnothrix and Pseudanabaena provide new insight into the taxonomy of these genera, reinforcing the need for taxonomic revision.

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Tidal controls on the formation of fine-scale sedimentary strata near the Amazon river mouth

Marine Geology ◽

10.1016/0025-3227(95)00015-q ◽

1995 ◽

Vol 125 (3-4) ◽

pp. 259-281 ◽

Cited By ~ 58

Author(s):

John M. Jaeger ◽

Charles A. Nittrouer

Keyword(s):

River Mouth ◽

Amazon River ◽

Fine Scale

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Using spectral analysis of Landsat-5 TM images to map coastal wetlands in the Amazon River mouth, Brazil

Wetlands Ecology and Management ◽

10.1007/s11273-013-9324-4 ◽

2013 ◽

Vol 22 (1) ◽

pp. 79-92 ◽

Cited By ~ 9

Author(s):

Gustavo F. Cardoso ◽

Carlos Souza ◽

Pedro Walfir M. Souza-Filho

Keyword(s):

Spectral Analysis ◽

Coastal Wetlands ◽

River Mouth ◽

Amazon River ◽

Landsat 5 Tm

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An extensive reef system at the Amazon River mouth

Science Advances ◽

10.1126/sciadv.1501252 ◽

2016 ◽

Vol 2 (4) ◽

pp. e1501252 ◽

Cited By ~ 109

Author(s):

Rodrigo L. Moura ◽

Gilberto M. Amado-Filho ◽

Fernando C. Moraes ◽

Poliana S. Brasileiro ◽

Paulo S. Salomon ◽

...

Keyword(s):

Bottom Topography ◽

River Mouth ◽

Amazon River ◽

Global Changes ◽

Western Atlantic ◽

Building Conditions ◽

Carbonate Sedimentation ◽

Tropical North Atlantic ◽

Associated Species ◽

Species Being

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 106–km2plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume’s eastward retroflection, conditions the existence of this extensive (~9500 km2) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth–ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.

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Reproductive aspects of Macrobrachium amazonicum (Decapoda: Palaemonidae) in the State of Amapá, Amazon River mouth

Acta Amazonica ◽

10.1590/s0044-59672014000200010 ◽

2014 ◽

Vol 44 (2) ◽

pp. 245-254 ◽

Cited By ~ 13

Author(s):

Jô de Farias Lima ◽

Luis Mauricio Abdon da Silva ◽

Thibério Carvalho da Silva ◽

Jamile da Silva Garcia ◽

Ilana da Silva Pereira ◽

...

Keyword(s):

Reproductive Output ◽

River Mouth ◽

Northeastern Brazil ◽

Amazon River ◽

Female Size ◽

Peak Period ◽

Macrobrachium Amazonicum ◽

General Aspects ◽

First Maturity ◽

Size At First Maturity

Macrobrachium amazonicum is an indigenous prawn vastly distributed in basins of South America, widely exploited by artisanal fisheries in northern and northeastern Brazil and, with great potential for aquaculture. This study aimed to investigate general aspects of population structure and reproductive characteristics (size at first maturity, fecundity and reproductive output) of M. amazonicum from two important areas to artisanal prawn fishing located at the mouth of the Amazon River, State of Amapá. The specimens were captured using 20 handcrafted traps called "matapi". A number of 5,179 prawns were captured, 2,975 females and 2,195 males resulting in 1.35:1 female to male ratio. Santana Island and Mazagão Velho showed females predominated in the population. A reproductive peak period was observed from January to April/2009 and in December/2010, coinciding with the period of higher rainfall. The recruitment peak occurred in June and July/2009. Egg-bearing females ranged in size (carapace length) from 11.10 to 29.6 mm. Fecundity increased with female size and reached up to 7,417 eggs. This amount of eggs is considered low if compared with other Macrobrachium estuarine species. Mean egg volume increased gradually from 0.121 to 0.24 mm³ during embryogenesis, representing 68.5% of overall increase from Stage I to Stage III. Eggs of M. amazonicum are small; this is typical for Macrobrachium species, which depends on brackish water to complete the larval development. Irrespective of female size, reproductive output of M. amazonicum varied between 4.8 and 21.85% of their body weight into eggs production.

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A new phreatic catfish of the genus Phreatobius Goeldi 1905 from groundwaters of the Iténez River, Bolivia (Siluriformes: Heptapteridae)

Zootaxa ◽

10.11646/zootaxa.1626.1.4 ◽

2007 ◽

Vol 1626 (1) ◽

pp. 51-58 ◽

Cited By ~ 4

Author(s):

LUIS FERNANDEZ ◽

LISANDRO J. SAUCEDO ◽

FERNANDO M. CARVAJAL-VALLEJOS ◽

SCOTT A. SCHAEFER

Keyword(s):

New Species ◽

River Basin ◽

River Mouth ◽

Amazon River ◽

Neural Spine ◽

Amazon River Basin ◽

Caudal Fin ◽

Near Surface ◽

Fin Ray ◽

Fin Rays

Phreatobius sanguijuela, new species, is described from an artificial well located within the Río Paraguá drainage, a tributary of the Río Iténez, Bolivia. The new species is distinguished from its sole congener, P. cisternarum, by the absence of eyes, presence of 25–34 (versus 42–50) dorsal procurrent caudal-fin rays, 14–16 (versus 22–26) ventral procurrent caudal-fin rays, and 45–46 (versus 54–59) vertebrae. Both Phreatobius species are phreatic and known only from artificial wells penetrating near-surface aquifers of the Amazon River basin. Material of the new species represents the first records of Phreatobius from the upper Amazon, some 2000 km from reported locations of P. cisternarum near the Amazon River mouth. Phreatobius can be readily distinguished among siluriforms by the following combination of characters: dorsal and ventral procurrent caudal-fin rays extended rostrally, continuous with anal fin ventrally; caudal fin round; anal-fin rays unbranched; mouth prognathous, with jaws displaced dorsally on head; adductor mandibulae muscle hypertrophied, covering most of skull and posteriorly inserting onto first neural spine; first pectoral-fin ray soft, not spinous; bright red in life. This species is under severe threat from overexploitation by local people, who routinely capture and destroy it on the presumption that it represents a dangerous parasite.

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