What happens in the darkness? Seasonal variations in tropical benthic fish assemblages

2020 ◽  
Vol 71 (4) ◽  
pp. 419
Author(s):  
C. Duarte ◽  
H. M. V. Espírito-Santo ◽  
J. Zuanon ◽  
L. H. Rapp Py-Daniel ◽  
C. P. Deus
Keyword(s):  
Species Composition ◽  
Amazon Basin ◽  
Fish Assemblages ◽  
Local Communities ◽  
Main Channel ◽  
Benthic Fish ◽  
Heterogeneous Landscape ◽  
Major Tributary ◽  
Temporal And Spatial ◽  
Using Data

Studies of fish assemblages have demonstrated that the main channels of rivers contain ichthyofauna adapted to this environment. However, information regarding the effects of temporal and spatial variations on this ichthyofauna is scarce. Using data from benthic fish assemblages in a major tributary of the Amazon basin collected during two consecutive receding and two rising water seasons, we tested the hypothesis that there are marked variations in community composition between the receding and rising water seasons. An asymmetry in predictability was detected among samples from the receding and rising seasons. Predictability in terms of species composition was higher for receding than rising seasons. The continual disassembly and reassembly cycles (due to dispersal) of local communities across a spatially heterogeneous landscape could explain this difference. Depth and dissolved oxygen affected the distribution of some benthic fish species during the rising seasons. This study highlights the important contribution of marginal wetlands to the benthic ichthyofauna inhabiting the main channel of the Purus River, as well as other major Amazonian rivers.

The Giving Up of Weekly Rest-Days by Migrant Domestic Workers in Singapore: When Submission Is Both Resistance and Victimhood

Social Forces ◽  
2019 ◽  
Vol 98 (4) ◽  
pp. 1695-1718
Author(s):  
Margaret Fenerty Schumann ◽  
Anju Mary Paul
Keyword(s):  
Work Experience ◽  
Home Country ◽  
Domestic Workers ◽  
Sociology Of Law ◽  
Signaling Mechanism ◽  
Contract Renewal ◽  
Temporal And Spatial ◽  
Using Data ◽  
Do So ◽  
Migrant Domestic Workers

AbstractWhy do so few live-in migrant domestic workers (MDWs) in Singapore utilize their weekly rest-day entitlement? Using data drawn from 3,886 online profiles of prospective MDWs and 40 interview sessions with MDWs, employers, and manpower agencies, we demonstrate how the industry encourages a “logic of submission” around rest-days. Through processual analysis, we unearth multiple, repeated moments of capitulation at key moments in a MDW’s work-life: (1) their interactions with a recruitment agency while still in their home country; (2) their matching with an overseas employer; (3) the duration of their two-year contract; and (4) the time of contract renewal. Submission to less frequent rest-days can secure their employability and financial mobility but also further individuates the MDW within the employer’s household and may lead to the engraining of a habitus of submissiveness towards their employers that can open the door to workers’ exploitation. We demonstrate how nationality and work experience further inflect this logic of submission to motivate non-Filipina and inexperienced MDWs to request even fewer rest-days than their counterparts. By combining feminist migration scholarship on Asian MDWs, with a sociology of law analysis, we offer up an example of how the same act of submission can simultaneously embody both resistance and victimhood depending upon the temporal and spatial scale used, and varying interpretations of the rest-day benefit as a much-needed respite, a monetizable benefit, or a signaling mechanism.

scholarly journals Regional and Seasonal Differences in Species Composition and Trophic Groups for Tidepool Fishes of a Western Pacific Island – Taiwan

2018 ◽  
Vol 23 (1) ◽  
pp. 1 ◽  
Author(s):  
Colin K. C. Wen ◽  
Li-Shu Chen ◽  
Kwang-Tsao Shao
Keyword(s):  
Species Composition ◽  
Fish Species ◽  
Fish Assemblages ◽  
Coastal Development ◽  
Species Number ◽  
Pacific Region ◽  
Trophic Groups ◽  
Species Numbers ◽  
Intertidal Fish ◽  
Intertidal Fishes

Spatial and temporal variations in the species composition of assemblages are common in many marine organisms, including fishes. Variations in the fish species composition of subtidal coral reefs have been well documented, however much less is known about such differences for intertidal fish assemblages. This is surprising, given that intertidal fishes are more vulnerable to terrestrial human disturbances. It is critical to evaluate the ecology and biology of intertidal fishes before they are severely impacted by coastal development, especially in developing countries such as those in the tropical western Pacific region where coastal development is rapidly increasing. In this study, we investigated the species composition, abundance, biomass and species number (richness) for intertidal fish assemblages in subtropical (northern) and tropical (southern) Taiwan across four seasons by collecting fishes from tidepools using clove oil. We also examined the gut contents of collected fishes to identify their trophic functional groups in order to investigate regional and seasonal variations for different trophic groups. We found significant differences in the species composition of tidepool fish assemblages between subtropical and tropical Taiwan. Bathygobius fuscus, Abudefduf vaigiensis and Istiblennius dussumieri were dominant species in subtropical Taiwan, whereas Bathygobius coalitus, Abudefduf septemfasciatus and Istiblennius lineatus were dominant in tropical Taiwan. Other species such as Bathygobius cocosensis, Abudefduf sordidus and Istiblennius edentulus were common in both regions. For trophic groups, omnivores and detritivores had or showed trends towards higher species numbers and abundances in the subtropical region, whereas herbivores, planktivores and general carnivores had or showed trends towards higher species numbers and biomass in the tropical region. Overall, many intertidal fish species and trophic groups showed differences in abundance, biomass and species number between subtropical and tropical Taiwan. Further studies on large scale geographical gradients in trophic groups and species compositions in the Indo-west Pacific region are encouraged to assist with ecosystem monitoring and assessment. Keywords: Intertidal fishes, spatio-temporal pattern, feeding guild, diet

scholarly journals Comparative Analysis of Distribution of Intertidal Fish Assemblages in Different Estuarine Systems on Northern Coast of Brazil

2017 ◽  
Vol 10 (2) ◽  
pp. 26 ◽  
Author(s):  
Milton Goncalves Silva Junior ◽  
Antonio Carlos Leal Castro ◽  
Ulrich Saint-Paul
Keyword(s):  
Comparative Analysis ◽  
Fish Assemblages ◽  
Coastal Region ◽  
Fish Fauna ◽  
Estuarine Fish ◽  
Northern Coast ◽  
Tidal Creeks ◽  
Estuarine Systems ◽  
Using Data ◽  
High Dynamics

The northern coast of Brazil has more than 30 estuaries distributed along 650 km of coastline. These conditions favor the presence of relatively large fish communities in estuarine environments, but published information on the fish fauna in tidal creeks in northern Brazil is only available for some mangrove systems, and comparative studies between fish estuarine communities in different tidal creeks are less common. The choice of the study area was based on the fact that it has been poorly investigated with regard to estuarine fish fauna in comparison in mangrove tidal creeks using the same fishing gear. The objective of the present study was to compare the composition of the relative biomass of taxonomic, functional and ecological guilds of fish assemblages occurring in estuarine systems along the northern coast of Brazil. The study area of the present comparative analysis extended from the southeastern edge of the Marajoara Gulf to the western edge of the Maranhense Gulf. A comparative analysis among different estuarine systems was performed using data from other studies. The abundance of juveniles was greater in the Caeté, Curuçá and Cururuca estuaries than other estuaries. Cluster analysis separated the estuaries into two distinct groups and significant differences between these groups only exist in relation to geographical proximity. The present investigation indicates that the coastal region between the states of Pará and Maranhão is characterized by high dynamics and environmental heterogeneity, particularly with regard to changes in river discharge and tidal fluctuations. The present results underscore the importance of ecological information on ichthyofauna in tropical estuaries in order to include appropriate descriptors in conservation or restoration processes of marine communities and habitats.

scholarly journals The contribution of environmental factors to fish assemblages in the Río Acahuapa, a small drainage in Central America

2017 ◽  
Vol 15 (3) ◽  
Author(s):  
Francisco S. Álvarez ◽  
Wilfredo A. Matamoros ◽  
Francisco A. Chicas
Keyword(s):  
Fish Species ◽  
Habitat Structure ◽  
Fish Assemblages ◽  
Species Abundance ◽  
Main Channel ◽  
Estuarine Fish ◽  
Species Origin ◽  
High Temperature Water ◽  
Distribution Of Fish ◽  
Temperature Water

ABSTRACT The ichthyofauna of the Río Acahuapa was analyzed sampling 17 sites that included the basin main channel and its tributaries. Fish were collected using dip-nets, seine-nets and electrofishing. Fish standard length and species abundance were recorded. Species origin and salinity tolerance criteria were used to classify fish species. Water physicochemical variables, habitat structure and sampling sites elevation were recorded. A total of 33 fish species were registered, 12.1% are primary, 45.5% are secondary and 42.4% are of marine derivation. Fish species richness declined with increase of elevation (R2=0.55, p=0.0006). Two assemblages of fishes were identified: the first one associated to sites of low elevations (19-184 masl), composed mainly of secondary and marine-estuarine fish species related with high temperature, water velocity, river width, dissolved oxygen and low sand and silt substrate cover; the second one associated to sites of middle and higher elevations (185-519 masl), composed by primary and secondary freshwater fishes related with high pH, logs and rocks substrate cover. In summary, elevation and environmental variables contributed to the composition and distribution of fish in the Río Acahuapa.

scholarly journals Applied science facilitates the large-scale expansion of protected areas in an Amazonian hot spot

2021 ◽  
Vol 7 (31) ◽  
pp. eabe2998
Author(s):  
Nigel C.A. Pitman ◽  
Corine F. Vriesendorp ◽  
Diana Alvira Reyes ◽  
Debra K. Moskovits ◽  
Nicholas Kotlinski ◽  
...  
Keyword(s):  
Land Use ◽  
Protected Areas ◽  
Large Scale ◽  
Amazon Basin ◽  
Hot Spot ◽  
Terrestrial Ecosystems ◽  
Local Communities ◽  
Decision Makers ◽  
Social Scientists ◽  
International Commitments

Meeting international commitments to protect 17% of terrestrial ecosystems worldwide will require >3 million square kilometers of new protected areas and strategies to create those areas in a way that respects local communities and land use. In 2000–2016, biological and social scientists worked to increase the protected proportion of Peru’s largest department via 14 interdisciplinary inventories covering >9 million hectares of this megadiverse corner of the Amazon basin. In each landscape, the strategy was the same: convene diverse partners, identify biological and sociocultural assets, document residents’ use of natural resources, and tailor the findings to the needs of decision-makers. Nine of the 14 landscapes have since been protected (5.7 million hectares of new protected areas), contributing to a quadrupling of conservation coverage in Loreto (from 6 to 23%). We outline the methods and enabling conditions most crucial for successfully applying similar campaigns elsewhere on Earth.

scholarly journals Morphological diversity of fish along the rio das Velhas, Minas Gerais, Brazil

2012 ◽  
Vol 10 (2) ◽  
pp. 417-424 ◽  
Author(s):  
Nara Tadini Junqueira ◽  
Cecília Gontijo Leal ◽  
Carlos Bernardo Mascarenhas Alves ◽  
Paulo Santos Pompeu
Keyword(s):  
Fish Assemblages ◽  
Morphological Diversity ◽  
Minas Gerais ◽  
Two Dimensions ◽  
Anthropogenic Pressures ◽  
Morphological Attributes ◽  
Morphological Organization ◽  
Minas Gerais State ◽  
Major Tributary ◽  
Euclidean Distances

The rio das Velhas, located in central Minas Gerais State (Brazil), is a major tributary of the rio São Francisco. Despite several anthropogenic pressures, this basin supports more than 115 fish species. The aim of this study was to compare the morphological space occupied by fish assemblages in four regions (headwaters, upper, middle, and lower course) along the channel of the rio das Velhas. We try to answer the following question: Is there a change in the morphological organization of the fish along the longitudinal gradient of the river? Individuals from 67 species, collected at several sites in the basin from 1999 to 2008, were measured for 11 morphological attributes related to swimming behavior and habitat use. Through the graphs, the first two dimensions of the PCA suggest that the morphological volume occupied by the headwaters region is smaller than the other sections, because of the low richness of the site. However, morphological hypervolumes of the four reaches analyzed by Euclidean distances were not statistically different. The results indicated that only the density of morphological types increases along the rio das Velhas, and there is no difference between the headwaters and upper courses. Therefore, in order to use functional groups related to the morphology of the species as tools to take measures for the conservation and revitalization of the rio das Velhas, it is necessary analyze the density of species within these groups, as well as their composition.

Sign in / Sign up

Export Citation Format

Share Document