Q.Profundal zone is predominated by heterotrophs in a pond ecosystem, because of

Ecosystems are classified first by origin — natural (occurring with or without human interference: forest, grassland, desert) versus artificial/manmade (deliberately created and maintained, e.g. a rice or maize field) — and natural ecosystems are further split by habitat into terrestrial (forest, grassland, desert) and aquatic, the latter dividing into lotic (running water — rivers, springs, streams) and lentic (standing water — ponds, lakes) freshwater systems, alongside marine systems. The pond ecosystem is studied here as a compact, classic example of a natural, aquatic, freshwater, lentic, self-sustaining and self-regulating system. Its abiotic components are dissolved inorganic substances (CO2, O2, calcium, nitrogen, phosphate) and organic substances (amino acids, humic acid) from dead matter, regulated by light, temperature, pH and other climatic conditions. Its biotic components cover producers (phytoplankton such as Oscillatoria and diatoms; filamentous algae such as Spirogyra; floating plants such as Azolla and Eichhornia; submerged plants such as Potamogeton; rooted-floating plants such as Nymphaea and Nelumbo; marginal macrophytes such as Typha), consumers (zooplankton like Paramoecium and Daphnia as primary consumers; benthos like molluscs and annelids; water beetles and frogs as secondary consumers; ducks, cranes, large fish, hawks and humans as tertiary/top carnivores), a …