Knowledge Drops - Biology 1: Knowledge Drops Biology, #1

Why do freshwater lakes & rivers seem to have less biological structure than oceans?

Freshwater lakes and rivers often appear to have fewer plants and animals compared to oceans because of a few important reasons.

Firstly, oceans receive more nutrients than freshwater systems. Nutrients are like food for plants and animals. In the ocean, there are many sources of nutrients, such as rivers that bring in nutrients from the land, and marine organisms that release nutrients when they die. These nutrients support the growth of tiny plants called phytoplankton, which are the foundation of the marine food chain. In freshwater, the amount of nutrients is usually lower, so there is less food available for plants and animals to grow and survive.

Secondly, the size and connections of oceans play a role. Oceans are vast and interconnected, allowing plants and animals to move around and find new places to live. This helps them find enough food and mates. It also allows for the exchange of genetic material, which leads to more diversity. In contrast, freshwater systems like lakes and rivers are often smaller and more isolated. They may not be connected to other bodies of water, which limits the movement of plants and animals. This means that the variety of species and interactions in freshwater systems can be less than in the ocean.

Finally, the stability of the environment is another factor. Oceans tend to have more stable conditions, such as constant water temperature and salinity. This stability allows marine organisms to adapt to specific habitats and develop specialized roles in the ecosystem. Freshwater systems can be more variable in their conditions, with changing water levels, temperatures, and other factors. This variability can make it more challenging for organisms to establish stable populations and complex relationships.

Overall, these factors contribute to the perception that freshwater lakes and rivers have less biological structure compared to oceans.

Did the beginning of the latest Ice Age cause widespread extinction?

Yes, the beginning of the latest Ice Age, known as the Pleistocene Epoch, did indeed cause the widespread extinction of various plant and animal species. During this period, which began approximately 2.6 million years ago and lasted until about 11,700 years ago, the Earth experienced a series of glacial and interglacial cycles, with alternating periods of colder and warmer temperatures.

The onset of the Ice Age led to significant changes in global climate and environment, including the expansion of ice sheets, the formation of glaciers, and changes in sea levels. These changes had a profound impact on ecosystems and the survival of many species.

The cooling temperatures and expanding ice sheets caused a decrease in available habitats and resources, which put pressure on numerous plants and animals. Many species that were adapted to warmer conditions and specialized environments struggled to survive in the harsher and more limited conditions of the Ice Age. Consequently, a significant number of species went extinct during this period.

Some of the well-known extinct species from the Pleistocene Epoch include the woolly mammoth, saber-toothed cats, giant ground sloths, and the Irish elk. These extinctions were likely a result of a combination of factors, including habitat loss, competition for resources, and the inability of some species to adapt to the changing