Searching for Sawfish: Investigating the Biogeographic Patterns of Pristis pectinata in a Global Species Distribution Model

Description
The smalltooth sawfish (Pristis pectinata) is a critically endangered species endemic to the Atlantic Ocean basin, with its range historically extending from the Gulf of Mexico to Brazil. Over the past century, the species has experienced severe population declines and

The smalltooth sawfish (Pristis pectinata) is a critically endangered species endemic to the Atlantic Ocean basin, with its range historically extending from the Gulf of Mexico to Brazil. Over the past century, the species has experienced severe population declines and a shrinking habitat due to human activity, including bycatch, habitat degradation, and illegal trade of its rostrum. Although primarily restricted to the southern coast of Florida, remnant populations may still exist in the Bahamas and along the West African coast. To support conservation efforts, species distribution models (SDMs) were employed to map the current and potential habitats of the smalltooth sawfish, incorporating occurrence data from public encounters and environmental variables from satellite sources. This study also examines habitat preferences across different age classes, identifying critical areas for protection. Findings highlight the influence of sea temperature, benthic salinity, and dissolved oxygen on sawfish distribution and potential differences in influences based on age classes. They underscore the need for targeted conservation measures to aid in population recovery. Future research should focus on expanding data collection in underrepresented areas and age classes to refine habitat suitability models further.

Details

Contributors
Date Created
2024
Resource Type
Language
  • eng
Note
  • Partial requirement for: M.S., Arizona State University, 2024
  • Field of study: Biology

Additional Information

English
Extent
  • 47 pages
Open Access
Peer-reviewed

Urban Pond Ecology at the Rio Salado Habitat Restoration Area

Description
When most people think of Phoenix, Arizona, they think of sprawling cityscapesand hot desert mountains full of saguaros and other cacti. They rarely think of water and fish, and yet, the Arizona landscape is home to many lakes, ponds, rivers and

When most people think of Phoenix, Arizona, they think of sprawling cityscapesand hot desert mountains full of saguaros and other cacti. They rarely think of water and fish, and yet, the Arizona landscape is home to many lakes, ponds, rivers and streams, full of both native fish and sportfish, including in the urban areas. According to the report by DeSemple in 2006, between the years 2001 and 2006, the Rio Salado Environmental Restoration Project worked to revitalize the dry river bed that runs through Phoenix, that included the construction of two urban ponds, the Demonstration Pond and the Reservoir Pond. At the start of this study, it was unknown what vertebrate species inhabited these ponds, but it was known that these urban ponds have been used to dump unwanted aquatic pets. The bluegill Lepomis macrochirus was found to reside in both ponds, and as it is such an important sportfish species, it was chosen as the focal species for these studies, which took place over periods in March, May, July, and September of 2021. Single-season occupancy models were used to attempt to determine how L. macrochirus, use the microhabitats within the system, and a multi-season model was used to estimate their recruitment, and seasonal changes in occupancy. In addition, this study also attempts to understand the size structures of the L. macrochirus population in the Reservoir Pond and the population in the Demonstration Pond, and if that size structure varies from March to September. As the populations of these ponds are physically isolated from one another, statistical tests were also done to determine if the size structures of the two populations of L. macrochirus differ from one another and found that the two populations do indeed differ from one another, but only during two of the sampling periods.

Details

Contributors
Date Created
2022
Topical Subject
Resource Type
Language
  • eng
Note
  • Partial requirement for: M.S., Arizona State University, 2022
  • Field of study: Applied Biological Sciences

Additional Information

English
Extent
  • 77 pages
Open Access
Peer-reviewed

The Effect of Nanofertilizers on the Soil Microbial Community

Description
As the global population continues to increase, so does the need for agriculture resulting in increased fertilizer use. Nanofertilizers and biochar have been proposed as alternatives to fertilizers currently in use to reduce negative environmental impacts. In this study, the

As the global population continues to increase, so does the need for agriculture resulting in increased fertilizer use. Nanofertilizers and biochar have been proposed as alternatives to fertilizers currently in use to reduce negative environmental impacts. In this study, the effects of various nanofertilizers and biochar on the soil microbial community were investigated. Soils treated with graphene nanoplatelet (GNP), graphene oxide (GO), reduced graphene oxide (rGO), graphite nano-additive (GNA) and biochar (BC) at concentrations of 5 mg/kg and 1000 mg/kg were sampled before and after a 28-day incubation period. Quantitative PCR assays were carried out against the following target genes: 16S rRNA, nirK, nirS, nifH, amoA and nosZ. Overall, all treatments experienced a decrease in 16S rRNA abundance after the incubation period with an average decrease of 48% however, all treatments were higher in abundance than the control. The abundances of nitrogen (N) cycling functional genes were evaluated in terms of relative abundance as a percentage of 16S rRNA. There was an increase across all treatments in nirK relative abundance over time and when compared to the control. The most notable differences in abundance were in rGO (high) as well as BC. Both nirS and nosZ exhibited an increase over time but decreased compared to the control. A decrease in relative abundances of nifH in BC as well as GO (low) and rGO (high) was observed. Lastly, there was an increase in amoA relative abundance across all treatments after the incubation period. However, all treatments were significantly lower than the control. The increase of denitrifying genes (nirK, nirS and nosZ) and nitrifying genes (amoA) suggests the potential increase in denitrification which can result in increased N loss into the atmosphere and the potential decrease of nitrification resulting in reduced N loss into waterways, respectively. At the time of writing, this study is one of the first to investigate and provide observations on the effects of nanofertilizers on nifH, which is responsible for N-fixation. The results presented here suggest that rGO and BC impart similar effects on the microbial community, whereas GNP had the most significant impact overall.

Details

Contributors
Date Created
2021
Topical Subject
Resource Type
Language
  • eng
Note
  • Partial requirement for: M.S., Arizona State University, 2021
  • Field of study: Applied Biological Sciences

Additional Information

English
Extent
  • 47 pages
Open Access
Peer-reviewed