scholarly journals Effects of enhanced hydrological connectivity on Mediterranean salt marsh fish assemblages with emphasis on the endangered Spanish toothcarp (Aphanius iberus)

2016 ◽  
Author(s):  
Patricia Prado ◽  
Carles Alcaraz ◽  
Lluis Jornet ◽  
Nuno Alberto Caiola ◽  
Carles Ibáñez
Keyword(s):  
Salt Marsh ◽  
Fish Community ◽  
Fish Assemblages ◽  
Fish Population ◽  
Important Variable ◽  
Hydrological Connectivity ◽  
Local Diversity ◽  
Large Numbers ◽  
Negative Effect ◽  
Migratory Movements

The hydrological connectivity between the salt marsh and the sea was partially restored in a Mediterranean wetland containing isolated ponds resulting from former salt extraction and aquaculture activities. A preliminary assessment provided evidence that ponds farther from the sea hosted very large numbers of the endangered Spanish toothcarp, Aphanius iberus, suggesting that individuals had been trapped and consequently reach unnaturally high densities. In order to achieve both habitat rehabilitation and toothcarp conservation, efforts were made to create a gradient of hydrologically connected areas, including isolated fish reservoirs, semi-isolated, and connected salt marsh–sea areas that could allow migratory movements of fish and provide some protection for A. iberus. The fish community was monitored prior to, and for three years after rehabilitation. Results showed an increase in the number of fish species within semi-isolated areas (Zone A), relative to connected areas (Zone B), while at the assemblage level, structural differences between zones were higher than interannual variability. GLMs evidenced that distance to the sea was the most important variable explaining the local diversity of the fish community after restoration, with occasional influence of other factors such as temperature, and depth. The abundance of A. iberus was consistently higher in semi-isolated areas at greater distances from the sea, but a decline occurred in both zones and in isolated reservoir ponds after restoration efforts, which may be attributable to dispersal to adjacent habitats, and to interannual differences in recruitment success. A negative effect of restoration works on fish population cannot be excluded, but the final outcome of the intervention likely needs a longer period .

scholarly journals Effects of enhanced hydrological connectivity on Mediterranean salt marsh fish assemblages with emphasis on the endangered Spanish toothcarp (Aphanius iberus)

2016 ◽  
Author(s):  
Patricia Prado ◽  
Carles Alcaraz ◽  
Lluis Jornet ◽  
Nuno Alberto Caiola ◽  
Carles Ibáñez
Keyword(s):  
Salt Marsh ◽  
Fish Community ◽  
Fish Assemblages ◽  
Fish Population ◽  
Important Variable ◽  
Hydrological Connectivity ◽  
Local Diversity ◽  
Large Numbers ◽  
Negative Effect ◽  
Migratory Movements

The hydrological connectivity between the salt marsh and the sea was partially restored in a Mediterranean wetland containing isolated ponds resulting from former salt extraction and aquaculture activities. A preliminary assessment provided evidence that ponds farther from the sea hosted very large numbers of the endangered Spanish toothcarp, Aphanius iberus, suggesting that individuals had been trapped and consequently reach unnaturally high densities. In order to achieve both habitat rehabilitation and toothcarp conservation, efforts were made to create a gradient of hydrologically connected areas, including isolated fish reservoirs, semi-isolated, and connected salt marsh–sea areas that could allow migratory movements of fish and provide some protection for A. iberus. The fish community was monitored prior to, and for three years after rehabilitation. Results showed an increase in the number of fish species within semi-isolated areas (Zone A), relative to connected areas (Zone B), while at the assemblage level, structural differences between zones were higher than interannual variability. GLMs evidenced that distance to the sea was the most important variable explaining the local diversity of the fish community after restoration, with occasional influence of other factors such as temperature, and depth. The abundance of A. iberus was consistently higher in semi-isolated areas at greater distances from the sea, but a decline occurred in both zones and in isolated reservoir ponds after restoration efforts, which may be attributable to dispersal to adjacent habitats, and to interannual differences in recruitment success. A negative effect of restoration works on fish population cannot be excluded, but the final outcome of the intervention likely needs a longer period .

scholarly journals Effects of enhanced hydrological connectivity on Mediterranean salt marsh fish assemblages with emphasis on the endangered Spanish toothcarp (Aphanius iberus)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3009 ◽  
Author(s):  
Patricia Prado ◽  
Carles Alcaraz ◽  
Lluis Jornet ◽  
Nuno Caiola ◽  
Carles Ibáñez
Keyword(s):  
Salt Marsh ◽  
Fish Community ◽  
Linear Models ◽  
Fish Assemblages ◽  
Marine Species ◽  
Fish Population ◽  
Important Variable ◽  
Hydrological Connectivity ◽  
Local Diversity ◽  
Negative Effect

The hydrological connectivity between the salt marsh and the sea was partially restored in a Mediterranean wetland containing isolated ponds resulting from former salt extraction and aquaculture activities. A preliminary assessment provided evidence that ponds farther from the sea hosted very large numbers of the endangered Spanish toothcarp,Aphanius iberus, suggesting that individuals had been trapped and consequently reach unnaturally high densities. In order to achieve both habitat rehabilitation and toothcarp conservation, efforts were made to create a gradient of hydrologically connected areas, including isolated fish reservoirs, semi-isolated, and connected salt marsh-sea areas that could allow migratory movements of fish and provide some protection forA. iberus. The fish community was monitored prior to, and for three years after rehabilitation. Results showed an increase in the number of fish species within semi-isolated areas (Zone A), whereas areas adjacent to the sea (Zone B) increased the number of marine species and decreased that of estuarine species (ES). Yet overall differences in fish assemblages were much higher between zones than among study years. Generalized linear models (GLMs) evidenced that distance to the sea was the most important variable explaining the local diversity of the fish community after restoration, with occasional influence of other factors such as temperature, and depth. The abundance ofA. iberuswas consistently higher in semi-isolated areas at greater distances from the sea, but a decline occurred in both zones and in isolated reservoir ponds after restoration efforts, which may be attributable to interannual differences in recruitment success and, to a lesser extent, to dispersal into adjacent habitats. A negative effect of restoration works on fish population cannot be excluded, but the final outcome of the intervention likely needs a longer period.

scholarly journals Fish and other faunal remains from a Late Iron Age site on the Letaba River, Kruger National Park

Koedoe ◽  
1991 ◽  
Vol 34 (1) ◽  
Author(s):  
Ina Plug ◽  
Paul Skelton
Keyword(s):  
Iron Age ◽  
National Park ◽  
Fish Population ◽  
Faunal Remains ◽  
Late Iron Age ◽  
Hunting Strategies ◽  
The People ◽  
Large Numbers ◽  
Fish Remains ◽  
Insight Into

Fish remains from Late Iron Age sites in the Transvaal are relatively scarce. It seems as if the people did not utilize the riverine resources extensively. Therefore the unique assemblage of large numbers of fish bones on a Late Iron Age site, provides some insight into the fish population of a section of the Letaba River a few hundred years ago. The presence of other faunal remains provides some information on prehistoric utilization of the environment in general. Hunting strategies and aspects of herding can also be deduced from the faunal remains.

Subsampling Reduces Sorting Effort for Waterfowl Foods in Salt-Marsh Core Samples

2014 ◽  
Vol 5 (2) ◽  
pp. 380-386 ◽  
Author(s):  
Mark C. Livolsi ◽  
Kevin M. Ringelman ◽  
Christopher K. Williams
Keyword(s):  
Salt Marsh ◽  
Food Availability ◽  
Carrying Capacity ◽  
Processing Time ◽  
Soil Core ◽  
Habitat Types ◽  
Core Samples ◽  
Large Numbers ◽  
Significant Difference ◽  
Time Savings

Abstract Waterfowl researchers often use soil core samples to estimate food availability in foraging habitats, and these estimates are needed for bioenergetic models of carrying capacity. However, core sampling is frequently a time- and resource-intensive process, and some researchers have suggested that subsampling may be a valuable way to reduce processing time. We evaluated whether 10% and 25% by mass subsampling are appropriate techniques for reducing core-sorting effort while maintaining precision for samples taken in six separate habitat types along the Delaware bayshore. We found no significant difference between biomass found in 100% sorted cores and estimated biomass obtained by 10% and 25% subsampling. We found that 10% subsampling offered the greatest time savings, reducing mean sorting times by 77% (from 13.7 hours to 3.3 hours) from 100% sorted cores. We recommend that researchers consider subsampling to reduce core-sorting effort and cost, particularly when processing large numbers of cores.

Predicting fish species richness and habitat relationships using Bayesian hierarchical multispecies occupancy models

2020 ◽  
Vol 77 (3) ◽  
pp. 602-610
Author(s):  
Shannon White ◽  
Evan Faulk ◽  
Caleb Tzilkowski ◽  
Andrew Weber ◽  
Matthew Marshall ◽  
...  
Keyword(s):  
Species Richness ◽  
Fish Community ◽  
Fish Assemblages ◽  
Similar Species ◽  
Occupancy Models ◽  
Imperfect Detection ◽  
Modeling Framework ◽  
Bayesian Hierarchical ◽  
Recreation Area ◽  
Species Occupancy

Understanding how stream fishes respond to changes in habitat availability is complicated by low occurrence rates of many species, which in turn reduces the ability to quantify species–habitat relationships and account for imperfect detection in estimates of species richness. Multispecies occupancy models have been used sparingly in the analysis of fisheries data, but address the aforementioned deficiencies by allowing information to be shared among ecologically similar species, thereby enabling species–habitat relationships to be estimated for entire fish communities, including rare species. Here, we highlight the utility of hierarchical multispecies occupancy models for the analysis of fish community data and demonstrate the modeling framework on a stream fish community dataset collected in the Delaware Water Gap National Recreation Area, USA. In particular, we demonstrate the ability of the modeling framework to make inferences at the species-, guild-, and community-levels, thereby making it a powerful tool for understanding and predicting how environmental variables influence species occupancy probabilities and structure fish assemblages.

How good is half a job? Part-time employment and job quality in the US

2019 ◽  
pp. 187-216
Author(s):  
Kenneth Hudson ◽  
Arne L. Kalleberg
Keyword(s):  
Labor Market ◽  
The United States ◽  
Work And Family ◽  
Job Quality ◽  
Retirement Benefits ◽  
Poverty Threshold ◽  
Large Numbers ◽  
Negative Effect ◽  
Part Time ◽  
Time Part

In January 2018, about 17 percent of the workforce in the United States had a part-time job. Part-time employment increased between 1955 and the 1980s as large numbers of women entered the workforce. Since then it has fluctuated in response to rising and falling unemployment. The majority of part-time workers are between 24 and 60 and about two-thirds are women, who often divide their time between work and family. Like other forms of nonstandard work, part-time workers are more likely to have bad jobs, and they are more apt to live in families that are poor, even when controlling for a multitude of labor related variables. Although some part-time jobs offer health and retirement benefits and wages above the poverty threshold, most do not. Only a small share of part-time jobs-between 16 and 17 percent-are located in the primary labor market. When compared to whites, we find that blacks, Hispanic non-citizens, and persons of mixed-race descent are more likely to work part-time. Part-time workers in these groups are also more likely to have jobs in the secondary labor market. Finally, we find that as percentage of part-time workers in occupations increases, the negative effect on job quality associated with the percentage of women in an occupation is greatly reduced or disappear

scholarly journals Species diversity and composition drive the aesthetic value of coral reef fish assemblages

2019 ◽  
Vol 15 (11) ◽  
pp. 20190703 ◽  
Author(s):  
Anne-Sophie Tribot ◽  
Julie Deter ◽  
Thomas Claverie ◽  
François Guillhaumon ◽  
Sébastien Villéger ◽  
...  
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Emotional Response ◽  
Online Survey ◽  
Fish Assemblages ◽  
Species Abundance ◽  
Aesthetic Value ◽  
Negative Effect ◽  
The Aesthetic

Cultural and recreational values of biodiversity are considered as important dimensions of nature's contribution to people. Among these values, the aesthetics can be of major importance as the appreciation of beauty is one of the simplest forms of human emotional response. Using an online survey, we disentangled the effects of different facets of biodiversity on aesthetic preferences of coral reef fish assemblages that are among the most emblematic assemblages on Earth. While we found a positive saturating effect of species' richness on human preference, we found a net negative effect of species abundance, no effect of species functional diversity and contrasting effects of species composition depending on species' attractiveness. Our results suggest that the biodiversity–human interest relationship is more complex than has been previously stated. By integrating several scales of organization, our study is a step forward in better evaluating the aesthetic value of biodiversity.

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