Primary productivity refers to the production of organic compounds through photosynthesis or chemosynthesis. Photosynthesis uses sunlight to convert carbon dioxide and water into glucose, while chemosynthesis uses chemical energy from inorganic nutrients. Oceanic productivity is influenced by the availability of nutrients and sunlight. Polar regions have limited productivity due to a lack of sunlight, while tropical regions have limited nutrients. Temperate regions balance both sunlight and nutrients for optimal productivity. Energy is inefficiently transferred between trophic levels in a food chain, so animals in complex food webs are more resilient.