- Title
- Morphometric variation, heavy metal analysis and temperature effects on body weight and stoichiometric ratios (C:N:P) of cerithidea decollata along the Wild Coast, South Africa
- Creator
- Fiki, Sinoxolo
- Description
- The truncated snail, C e rit hid e a d e c olla t a , is one of the major invertebrates in mangrove ecosystems. It’s the rapid ecophysiological response to environmental stress conditions makes C. decollata an ideal species to test the effects of climate change in mangrove ecosystems. Increased temperatures, due to climate change, is one of the major threats faced by aquatic invertebrates as thermal stress may easily lead to death. This study, thus, compared the effects of 1) environmental conditions on the morphology; 2) temperature on body weight and stoichiometry as well as 3) the heavy metal content of C. decollata across three mangrove ecosystems. Morphometry results revealed that sites significantly influenced most of the shell morphological variables (i.e., shell length, shell width, spire height and aperture width). However, sites did not significantly influence the shell depth and aperture length of C. decollata . Temperature effects on body weight revealed that C. decollata individuals gained weight at low temperatures (10 to 20 °C) in all sites. As a result, the mean % weight gain of 6.75 ± 0.11 in Mngazana, 15.82 ± 0.13 in Mbhashe and 11.2 ± 0.13 in Nqabara. Contrary, C. decollata lost weight at temperatures between 25 and 40 °C across all sites leading to a mean % weight loss of 9.51 ± 0.05 in Mngazana; 14.52 ± 0.16 in Mbhashe and 25.74 ± 0.12 in Nqabara. Stoichiometric analysis revealed that soft tissues had higher nitrogen, carbon and phosphorous than the shells. The NP ratio was higher in soft tissues than in shells while CN and CP ratios were higher in shells than in soft tissues. The N, C, P, CN, CP and NP were lowest in Mngazana and highest in Nqabara. Temperature increases resulted in increased nitrogen, phosphorous, carbon and their stoichiometric CN, CP and NP ratios. Heavy metal results showed that Zn, Cu and Cd were highest in the soft tissue than in the shells and sediment. Contrarily, Fe and Pb were higher in the sediment than in shells and soft tissues. The Cu+Zn was highest in the shells than in the soft tissues and sediment. However, arsenic concentrations were below detection levels across all sites. Overall, no significant site differences were detected for heavy metals. It was, therefore, concluded that sites influenced some of C. decollata morphological features while temperature affected the body weight and stoichiometry of C. decollata .
- Description
- Thesis (Masters) -- Faculty of Natural Sciences, 2023
- Date
- 2023-07
- Subject
- Zoology
- Type
- Masters theses, text
- Identifier
- http://hdl.handle.net/11260/9388
- Identifier
- vital:73512
- Format
- computer, online resource, application/pdf, 1 online resource (106 pages), pdf
- Publisher
- Walter Sisulu University, Faculty of Natural Sciences
- Language
- English
- Rights
- Walter Sisulu University, All Rights Reserved, Open Access
- Hits: 466
- Visitors: 310
- Downloads: 13
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details | SOURCE1 | Fiki, Sinoxolo.pdf | 3 MB | Adobe Acrobat PDF | View Details |