If a toxic chemical would be introduced to the rainforest, it would effect the biomass of the whole environment. The toxin would be absorbed into the ground first, where it would then be used as food for the plants. Then the plants would have the toxic chemical in them, and when the primary consumers eat the plants, then they would gather the toxins too through the process of bioaccumulation. Then the toxin will be passed on from the primary consumers to the secondary consumers to the tertiary consumers, and finally to the apex predator. Eventually the toxin will build up through a process called biomagnification so much that it will end up killing many of the animals in the ecosystem. The Bengal tiger, being the apex predator and a fairly large animal wouldn't be killed by the chemical, but some of its prey would be killed off. Then the Bengal tiger wouldn't have anything to eat, and would therefore die.
If the slug would die out, then the frog would have nothing to eat, forcing it to move habitats or die out. If there were no more frogs in the environment, then the anaconda wouldn't have enough food to eat. Then the jaguar, which eats the anaconda, would have to find another source of food, and that would be difficult for the jaguar to adapt to hunting a different kind of food than what it's used to.
If the slug would die out, then the frog would have nothing to eat, forcing it to move habitats or die out. If there were no more frogs in the environment, then the anaconda wouldn't have enough food to eat. Then the jaguar, which eats the anaconda, would have to find another source of food, and that would be difficult for the jaguar to adapt to hunting a different kind of food than what it's used to.