I also authorize Chittagong Veterinary and Animal Sciences University (CVASU) to lend this dissertation to other institutions or individuals for the purpose of scientific research. EFFECT OF ACIDIFICATION ON LARVAL FISH NUMBERS IN REZ KHAL ESTUARY, COX’S BAZAR COASTS, BANGLADESH. All praises and thanks to Almighty Allah, who enabled her to complete the research work and successfully write her dissertation for the title of Master of Science (MS) in Fisheries Resource Management and gave her the strength to complete the research work within the stipulated time.
Mohammad Alamgir Hossain, Department of Pathology and Parasitology, Chattogram Veterinary and Animal Sciences University, Chattogram for his valuable supervision and guidance. Sk Ahmad Al Nahid, Associate Professor and Director, Department of Fisheries Resource Management, Chattogram Veterinary and Animal Sciences University, Chattogram for his valuable guidance, intellectual suggestions, knowledge and patience. Bokhteyar Hossain, Supriya Biswas and the support staffs of the ecology laboratory, Faculty of Fisheries, Chattogram Veterinary and Animal Science University (CVASU) for their help during the sample examination in the laboratory.
Last but not the least, the author expresses her deepest sense of gratitude and heartfelt respect for feelings towards her beloved family members for their immense sacrifice, blessings and encouragement. Appendix A Hydrological parameters of Rezu Khal 43 Appendix B Derived ocean acidification factors of Rezu Khal 43 Appendix C Abundance of fish larvae (1000/m3) at Rezu Khal 44.
Abstract
Introduction
- Background
- Significance of the research
- Objectives of the research
Ocean acidification generally occurs when seawater acidity increases or pH becomes low due to the breakdown of elevated CO2 in the atmosphere (Feely et al., 2008). Another consequence can be described by increased mineralization of dissolved organic matter and Primary Producer such as phytoplankton due to global warming (Mostofa et al., 2013). Ocean acidification has been documented as a crucial driving factor in changing the natural process (Doney et al., 2012).
The survival rate of fish larvae is strongly influenced by variation in growth and maturity (Houde, 1997), which may be related to altered metabolic demand or distribution of metabolic energy demands (Matson et al., 2012). Some researchers suggest that increased temperatures for extended periods of time may influence fish population declines (Cheung et al., 2012). There is evidence that increasing CO2 and decreasing pH in ocean water can alter the growth maturity of several marine organisms (Fabry et al., 2008).
Therefore, an increase in CO2 is considered to be detrimental to the recruitment, development (Baumann et al., 2012) and ecological behavior of various marine organisms (Munday et al., 2009). The input of elevated CO2 to the atmosphere affects calcifying marine species, but the availability of carbonate ions in the water, which are necessary for the calcification process, has decreased (Fabry et al., 2008).
Chapter 2 Review of literature
Munday et al., (2011) conduct experiment on the effect of ocean acidification on the growth of otoliths in tropical marine fish larvae. This finding suggests that the early life stages of whale pollock are resilient to the direct physiological effects of ocean acidification in terms of their growth potential. Kroeker et al., (2013) studied the impact of ocean acidification on marine organisms: quantifying sensitivity and interaction with warming.
Mostofa et al., (2016) review and synthesize the effects of ocean acidification on marine ecosystems, together with their potential negative impacts on marine organisms, ecosystem services and processes, and suggest that the marine environment is strongly affected by increasing acidity, making it mortality rate of marine animals increases. fish larvae, especially invertebrates. Munday et al., (2009) investigated the increase in CO2 and the effects of ocean acidification on the early developmental cycle of tropical marine fish, showing that reduced pH does not affect the maximum swimming speed of larvae in the settlement phase . Rossi et al., (2015) investigated the increase in fish larval development due to ocean acidification and also showed that there is still a gap between ontogenetic growth and the timing of orientation behavior, which for larvae can cause difficulties in finding habitat or establishment. in an unfavorable habitat.
Munday et al., (2010) conducted an experiment on ocean acidification, which poses a threat to the recovery of fish populations. Ishimatsu et al., (2005) studied the effects of a high CO2 atmosphere on the physiological functions of fish and revealed that hypercapnia directly affects vital physiological functions such as respiration, circulation and metabolism.
Materials and Methods
Results
- Correlation matrix
The results of hydrological water parameters, acidification factor and larval abundance of the sampling station are shown in the graph. 4.1) Water parameters 4.1.1) Temperature. The number of larvae, the water parameter and the ocean acidification factor were analyzed using the SPSS program, the derived value of which is shown in Table 4.1. A negative correlation was found between PCO2, pH and larval abundance and a positive correlation between pH and larval abundance, which are shown below the table (tab 4.1, tab 4.2 and tab 4.3).
Chapter 5 Discussion
- Water Temperature
- Water pH
- Alkalinity
- Salinity
- Ocean acidification factors
- Relation of fish abundance and pCO 2
- Fish abundance relates with pH
- Correlation between pH & pCO 2
- Correlation between pCO 2 & larvae abundance
- Correlation between pH & larvae abundance
Alkalinity of Bakkhali River was 146.85 mg/l according to a study on Physicochemical Assessment of Groundwater and Surface Water Quality in Greater Chattogram Region of Bangladesh (Ahmed et al., 2010). The salinity of seawater is increased by evaporation and decreased by the addition of freshwater through runoff or precipitation that neutralizes seawater (Hasan et al., 2019). Salinity levels in the water of the Bakkhali River fluctuated periodically, with a value of 12 ppt in summer and 27 ppt in winter, based on one investigation (Raknuzzaman et al., 2018).
From a partial pressure (pCO2) of about 280 µatm to its current level of nearly 400 µatm, the concentration of atmospheric carbon dioxide (CO2) increased by nearly 40% (Solomon et al., 2007). The optimum level of DIC- for living organism is considered to be less than.002 mol/kg (Spyres et al., 2000). In marine environment, biological organisms became stressed when aragonite saturation level is below 3 and shell structure started to dissolve below 1 (Jiang et al., 2015).
Larval numbers were quite high in April, July, August, September and October when the pCO2 level fluctuates greatly. The number of larvae was the lowest in March when the pCO2 value was lower. 550 μatm) have a crucial influence on larval development, which is considered the main factors of ocean acidification for living organisms (Diaz et al., 2019). There is a negative correlation between larval abundance and pCO2, and a pCO2 level above 300 µatm has a negative effect on the number of fish larvae (Scanes et al, 2014).
The number of larvae was found quite high in April, July, August and September, although the pH did not fluctuate significantly. Research on larval development has so far shown how low acidity greatly reduces survival (Kikkawa et al., 2003). Compared to adding acid on its own, CO2-induced acidification has more negative effects (Hayashi et al., 2004).
According to Pearson correlation, it means that if the value is in between, the correlation between the two variables is very strong and the negative value means negative correlation. According to Pearson correlation, if the value is between, it means the correlation between the two variables. According to Pearson correlation, if the value is in between, it means that the correlation between the two variables is weak and the positive value means positive correlation.
Chapter 6 Conclusion
Chapter 7 Recommendation
Reduced early life growth and survival in a fish in direct response to elevated carbon dioxide. Comparison of the acid-base responses to CO2 and acidification in Japanese flounder (Paralichthys olivaceus). Effect of ocean acidification on brood size and larval growth of walleye (Theragra chalcogramma).
Are larvae of demersal fish plankton or nekton?. 2008). Composition, abundance and distribution of fish larvae in the Bay of Bengal.SEAFDEC, Thailand, 93-124. Study of immigration of commercially important postlarvae of penaeids in the Chakaria Estuary, Cox's Bazar Bangladesh (Doctoral Thesis, Institut Akuakultur Tropika). Development under elevated p CO2 conditions does not affect lipid utilization and protein content in early life history stages of the purple sea urchin, Strongylocentrotus purpuratus.
Ocean warming increases malformations, premature hatching, metabolic suppression and oxidative stress in the early life stages of a cornerstone squid. Ocean acidification promotes the development of larvae, but reduces the opportunity for successful establishment. Observed changes in ocean acidity and carbon dioxide exchange in the coastal Bay of Bengal - a link with air pollution.
Increased acidification rates due to deposition of atmospheric pollutants in the coastal Bay of Bengal. Effects of ocean acidification on the swimming ability, development and biochemical responses of sand smelt larvae. Climate Change 2007 - The Physical Science Basis: Contribution of Working Group I to the IPCC Fourth Assessment Report (Vol. 4).
Role of river discharge and warming on ocean acidification and pCO2 levels in the Bay of Bengal.
Appendices
