Chapter 19, Problem 33A

Summary Introduction

To analyze : 

The effects that are caused due to the killing of all the phytoplankton by the marine parasite.

Introduction :

Phytoplankton belongs to the first trophic level of a food chain. They are the autotrophs that synthesize organic nutrients from inorganic raw materials with the help of solar radiation not only for themselves but for the organisms of other trophic levels also. Thus, in an ecosystem, the organism passes the food and its contained energy. As each member becoming the food of the later member of the sequence.

Explanation of Solution

In an aquatic ecosystem, the first trophic level is constituted by phytoplankton. Phytoplanktons are photosynthetic organisms and can manufacture organic food from inorganic raw material. The organic food produced by producers consists of all the nutrients such as carbohydrates, proteins, etc. it also contains energy. A part of the food is used up by themselves in providing various body activities. The rest amount of energy is employed in their bodybuilding that enters the food chain as food for consumers. 

The phytoplanktons are the producers. If a marine parasite kills all the phytoplankton in an ecosystem, then it will lead to the disruption of the food chain or food webs. It is because only they can fix the radiant energy into chemical energy that is utilized by the organisms of the other trophic levels, such as zooplankton, small crustaceans, etc. It will result in larger aquatic organisms such as fishes, etc to die and the collapse of the marine ecosystem.

Conclusion

Thus it can be concluded that phytoplanktons are an essential part of a marine ecosystem. They are the producers on which all the other marine organisms are either directly (herbivores) or indirectly (carnivores) dependent. Their elimination by marine parasites will result in the disruption of the marine ecosystem.