Such low DO waters do not cause impacts during high tide due to dilution effect. However, impact was significant in low tide. This is because as DO levels in the marine habitat can fluctuate greatly with the amount of bacteria present in the site, Therefore, when DO declines below threshold levels, which vary depending upon the species, mobile animals must move to waters with higher DO; immobile species often perish. If the concentration of DO fall further, many species will often become stressed and immobile species may die (hypoxia). A second condition, known as anoxia, occurs when the water becomes totally depleted of oxygen and results in the death of any organism that requires oxygen for survival. Such indicator is important because DO affects the growth, survival, distribution, behaviour and physiology of fish.