scholarly journals Diet and feeding strategy of the dusky grouper Mycteroperca marginata (Actinopterygii: Epinephelidae) in a man-made rocky habitat in southern Brazil

2011 ◽  
Vol 9 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Mario V. Condini ◽  
Elisa Seyboth ◽  
João P. Vieira ◽  
Alexandre M. Garcia
Keyword(s):  
Feeding Strategy ◽  
Marine Species ◽  
Southern Brazil ◽  
Patos Lagoon ◽  
Additional Tool ◽  
Rocky Habitat ◽  
Dusky Grouper ◽  
Dietary Shifts ◽  
Rocky Habitats ◽  
Rocky Bottoms

The dusky grouper (Mycteroperca marginata) is a marine species usually associated with rocky bottoms and reefs. The present work investigated the diet and feeding strategy of a dusky grouper population inhabiting a 4.5 km long pair of rocky jetties located in the mouth of Patos Lagoon estuary. No prior research has been conducted in such man-made habitat and the current study provides a basis for comparative studies on the diet of the dusky grouper populations inhabiting natural vs. man-made rocky habitats. Similarly with previous studies on natural substrates, crabs and fishes were the main food categories consumed (%IRI = 85.1 and %IRI = 12.6, respectively), whereas shrimps and mollusks had lower importance in the diet (%IRI = 1.9 and 0.4, respectively). As previously reported for dusky grouper populations inhabiting reefs and rocky bottoms, the present work revealed conspicuous size related dietary shifts. Blue crabs and fishes become increasingly important food items in the diet of larger individuals (> 500 mm, TL). Finally, it was found that the studied dusky population has a generalist feeding strategy with a high between-individual variation in prey consumption. Such strategy remained similar across the size increment of the species. Our findings suggest that man-made rocky substrates provide suitable feeding grounds for the dusky grouper in southern Brazil and could be used as an additional tool in the conservation efforts of this endangered species.

scholarly journals Age, growth, and reproductive aspects of the dusky grouper Mycteroperca marginata (Actinopterygii: Epinephelidae) in a man-made rocky habitat in southern Brazil

2011 ◽  
Vol 9 (4) ◽  
pp. 849-856 ◽  
Author(s):  
Elisa Seyboth ◽  
Mario V Condini ◽  
Cristiano Q Albuquerque ◽  
Antônio S Varela Jr ◽  
Gonzalo Velasco ◽  
...  
Keyword(s):  
Brazilian Coast ◽  
Patos Lagoon ◽  
Growth Coefficient ◽  
Spawning Site ◽  
Southwestern Atlantic Ocean ◽  
Rocky Habitat ◽  
Average Water ◽  
Dusky Grouper ◽  
Post Spawning ◽  
Growth And Reproduction

The dusky grouper, Mycteroperca marginata, is an important commercial marine fish that is currently considered an endangered species worldwide and listed as overexploited in Brazil. Although its reproductive biology has been studied elsewhere, no information is available for populations in its southernmost distribution limit on the Brazilian coast. The present work investigates age structure, growth and reproduction of individuals inhabiting a pair of rocky jetties, about 4.5 km long each, located in the mouth of Patos Lagoon in the municipality of Rio Grande, in the southwestern Atlantic Ocean. A total of 130 individuals obtained between February 2007 and May 2009 were analyzed, with total length ranging from 260 to 800 mm. The growth coefficient found in the present study (K: 0.069) was lower than values reported for dusky grouper populations from the Mediterranean Sea (0.087) and southeast Africa (0.09). This difference could be related to higher average water temperatures in these regions compared to the current study site or due to poorer habitat quality in terms of the shelters available for dusky grouper individuals to establish their territories. Microscopic ovarian analyses of individuals during three years of sampling revealed only the occurrence of immature and resting females. The absence of ripe or post-spawning individuals, associated with low GSI values (<0.2) over the studied months, indicates that the dusky grouper did not use this man-made rocky substrate as a spawning site. The current L50 estimate of 451.3 mm indicates that most individuals captured in this area are immature. Such fishing pressure on immature specimens, associated with its slow growth rates and complex reproductive characteristics, threatens sustainability of the current dusky grouper fishery at the study site.

By-catch analysis of Argentinean prawn Artemesia longinaris (Decapoda: Penaeidae) in surrounding area of Patos Lagoon, southern Brazil: effects of different rainfall

2011 ◽  
Vol 91 (5) ◽  
pp. 1059-1072 ◽  
Author(s):  
L.F.C. Dumont ◽  
F. D'Incao
Keyword(s):  
Juvenile Fish ◽  
Marine Species ◽  
Southern Brazil ◽  
Target Species ◽  
Surrounding Area ◽  
Patos Lagoon ◽  
Low Salinity ◽  
Top Predators ◽  
Incidental Catch ◽  
By Catch

One of the most problematic fishing methods in terms of by-catch and discarding is prawn-trawling. This paper analyses the incidental catch of an artisanal trawl fleet during two discrete Artemesia longinaris fishery seasons (2002 and 2004). The fishery season of A. longinaris operates monthly and it takes place in the surrounding area of the Barra do Rio Grande. Sampling was carried out during the fishing season (April–December) always on the same artisanal trawl boat. An observer was included on-board to avoid loss of information due to discards made by the fishermen at sea. Fifty species were caught: 38 fish and 12 crustaceans. Discrete fauna abundance and composition were recorded in analysed years, with higher by-catch ratios associated with elevated rainfall and low salinity. The overall discard ratio was 1:5.6, with values ranging from 1:11.3 in 2002 to 1:2.5 in 2004. The most striking differences between both years analysed were observed during autumn (1:75 in 2002 and 1:11.30 in 2004) and winter (1:16 in 2002 and 1:0.97 in 2004), while spring presented similar values (1:8 in 2002 and 1:4 in 2004). The discard ratio estimated in terms of number showed a different pattern, presenting overall values of 1:2.24 in 2002 and 1:0.5 in 2004. Higher estuarine runoff may have increased biomass production in the surrounding area of Patos Lagoon during 2002, sustaining higher abundance of estuarine-related and marine species in the area, as well as higher mean trophic level and abundance of top-predators. Conversely, A. longinaris production was consistently lower, since this marine species does not tolerate marked reductions in salinity. In 2004, salinity was higher, associated with low rainfall and favouring A. longinaris abundance in the area. During this dry year, the target-species was dominant in samples resulting in very low by-catch ratios, especially in winter (1:0.97). The catch was mainly composed of juvenile fish, since fishery is performed in nursery grounds.

scholarly journals Temporal Variability of Suspended-Solids Concentration in the Estuarine Channel of Patos Lagoon, Southern Brazil

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 646
Author(s):  
Rafael André Ávila ◽  
Priscila Mulattieri Suarez Orozco ◽  
Mauro Michelena Andrade ◽  
Osmar Olinto Möller
Keyword(s):  
Temporal Variability ◽  
Suspended Solids ◽  
Southern Brazil ◽  
Patos Lagoon ◽  
Reliable Technique ◽  
Acoustic Data ◽  
Solids Concentration ◽  
Estuarine Hydrodynamics ◽  
Inflow Conditions

The assessment of suspended-solids dynamics is crucial for the effective monitoring of estuarine environments. As the recurring in-situ sampling is usually problematic, the calibration of the backscattering from acoustic Doppler profilers has shown to be a reliable technique to estimate the suspended-solids concentration (SSC) in estuaries and rivers. In this study, we obtained a linear model that provides SSC estimates for the estuarine channel of Patos Lagoon by calibrating turbidity and acoustic data with in-situ concentration samples. The model output was analyzed in terms of its relationship with estuarine hydrodynamics and temporal variability. In this estuary, the supply of suspended solids is known to be due the runoff from its main tributaries, but also through the exchanges between the estuary and the coastal ocean. Both sources provide sediments and organic solids which affect water quality, geomorphology, and harbor operations. Results show that SSC is strongly linked to estuarine hydrodynamics, where concentrations increase with streamflow. During outflow periods, higher concentrations are associated with river runoff, whereas with inflow conditions they are induced by southern and southwesterly winds. However, relationship between SSC and streamflow is asymmetrical, meaning that the largest concentrations are majorly linked to outflow currents and downstream transport.

Reproductive biology of the dusky grouper (Epinephelus marginatus) at the southern limit of its distribution in the south-western Atlantic

2014 ◽  
Vol 65 (2) ◽  
pp. 142 ◽  
Author(s):  
Mario V. Condini ◽  
Luís F. Fávaro ◽  
Antonio S. Varela ◽  
Alexandre M. Garcia
Keyword(s):  
Reproductive Activity ◽  
The South ◽  
Western Atlantic ◽  
Spawning Period ◽  
Southern Limit ◽  
Rocky Reefs ◽  
Dusky Grouper ◽  
First Maturity ◽  
Rocky Bottoms ◽  
Partial Spawner

We investigated the reproductive parameters of a dusky grouper Epinephelus marginatus population at the southern limit of its distribution in the south-western Atlantic. The analysed specimens were captured between January 2008 and April 2011 at Carpinteiro Bank (CB) (32°16′S; 051°47′W), a seamount located at the 20 m isobath ~16 nautical miles from the coast. The gonads of a total of 201 individuals (184 females, 16 males and 1 individual in sexual transition) with a total length (TL, mm) between 278 and 1160 mm were analysed microscopically. Histological analyses of the gonads suggested that the species is a partial spawner with a long spawning period (between November and March) and with a reproductive peak between November and January. The average female length at first maturity (L50) was 496 (TL, mm). We also observed partially spawned ovaries and partially spawned testes, which indicated reproductive activity, and we noted the presence of hyalinised follicles. These findings reveal that CB is the southernmost portion of the south-western Atlantic in which the dusky grouper reproduces. Additionally, an inshore-offshore comparison suggested that deeper (>20 m) rocky bottoms, such as the studied seamount, constitute higher quality habitats for this species when compared with littoral (<5 m) rocky reefs.

Archaeological Earthen Mound Complex in Patos Lagoon, Southern Brazil: Chronological Model and Freshwater Influence

Radiocarbon ◽  
2017 ◽  
Vol 59 (1) ◽  
pp. 195-214 ◽  
Author(s):  
Rafael G Milheira ◽  
Kita D Macario ◽  
Ingrid S Chanca ◽  
Eduardo Q Alves
Keyword(s):  
Archaeological Sites ◽  
Human Intervention ◽  
Southern Brazil ◽  
Patos Lagoon ◽  
Lagoon System ◽  
Indigenous Groups ◽  
Freshwater Influence ◽  
Intense Activity

AbstractIn the present work, we assess the chronology of archaeological sites known as earthen mounds, commonly found at the Pampas biome, among the lowlands of Brazil, Uruguay, and Argentina. We focused on the Pontal da Barra settlement, which is a testimony of the long-term occupation of indigenous groups in the swamp and wet environment of Patos Lagoon, southern Brazil. A Bayesian chronological model based on the radiocarbon (14C) dating of 17 samples of fish otolith, 5 charcoal fragments, and 2 bones (human and dog) allowed determination of the beginning of the occupation as well as the occupational synchronism of the different mounds. The nature of the samples allows us to study the local 14C reservoir effect through the comparison between the group of marine and terrestrial samples, deriving a reservoir offset value of 63±53 14C yr for this particular area, indicating a strong freshwater influence in the lagoon system. We estimate the start of human intervention in the landscapes of southern Patos Lagoon to be around 2200 cal BP, with the most intense activity between 1800 and 1200 cal BP.

Characterization of a mud deposit offshore of the Patos Lagoon, southern Brazil

2009 ◽  
Vol 29 (3) ◽  
pp. 597-608 ◽  
Author(s):  
Allen H. Reed ◽  
Richard W. Faas ◽  
Mead A. Allison ◽  
Lauro J. Calliari ◽  
K.T. Holland ◽  
...  
Keyword(s):  
Southern Brazil ◽  
Patos Lagoon ◽  
Mud Deposit

scholarly journals Long-term changes in diversity in a subtropical estuary in southern Brazil

2018 ◽  
Author(s):  
Jose H Muelbert ◽  
Clarisse Odebrecht ◽  
Margareth Copertino ◽  
Erik Muxagata ◽  
Andre L Colling ◽  
...  
Keyword(s):  
Diversity Index ◽  
Salt Water ◽  
Salt Water Intrusion ◽  
Systematic Sampling ◽  
Southern Brazil ◽  
Species Diversity Index ◽  
Patos Lagoon ◽  
Dominant Feature ◽  
Long Term Ecological Research

The Patos Lagoon (10,000 km2) is the dominant feature in the coastal plain of Southern Brazil. The estuary of the Patos Lagoon (32° 05' S, 52° 10'W) and adjacent coast were chosen as a SITE (1,500 km2) for the Brazilian Long Term Ecological Research (LTER). This region presents high biological productivity and at the same time is host of important port and industrial activities. From 2000 to 2015, systematic sampling of physico-chemical variables and of the main constituents from plankton, benthos and nekton was conducted monthly. Species diversity index were calculated to express changes in diversity in the estuary. The estuary is a river-dominated system with discharge maxima associated with strong rainfall and low discharge periods occurring during drought years. This has direct influence on the circulation and salinity variations, with low values recorded during El Niño and high salt-water intrusion during La Niña years. Results reveal that species composition of phytoplankton, zooplankton, benthic flora and macrofauna in the estuary are all affected by different scales of variability. The fact that ENSO is a dominant forcing factor in the region highlights the importance of long term monitoring of biological components of coastal and ocean observing systems.

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