Question

Биологи установили такую парадоксальную зависимость, как только на каком-нибудь водоеме истребляют выдр так сразу становится больше рыбы. Но вскоре ее становится гораздо меньше. Если снова в водоеме появляется выдры то снова рыбы становятся больше. Почему?

Answer 1

Выдры питаются рыбой, поэтому при истреблении выдр численность рыб сначала увеличивается. Но выдры и регулируют эту численность, истребляя заболевших рыб. А при их отсутствии 1)больные рыбы разносят болезни. умирают, и их численность снижается 2) при большом количестве рыб снижаются запасы корма 3) рыбы начинают питаться своей молодью 4) усиливается межвидовая агрессия рыб. Появление выдр вновь включает эту регуляцию: происходит истребление в первую очередь неполноценных рыб, устраняются факторы, снижающие численность рыб. И вырастает больше здоровых рыб.

Answer 2

The Paradoxical Relationship Between Otters and Fish Population

Biologists have observed a paradoxical relationship between otters and fish populations in certain bodies of water. When otters are present and actively hunting, the fish population initially increases. However, over time, the fish population decreases. Conversely, when otters are absent, the fish population decreases, but if otters return, the fish population increases again. This phenomenon has been studied to understand the underlying reasons for this pattern.

Explanation of the Paradox

The paradoxical relationship between otters and fish population can be explained by considering the ecological dynamics at play. When otters are present in a water body, they actively hunt and consume fish. This predation pressure initially reduces the fish population. However, the presence of otters also indirectly benefits the fish population by reducing the population of other fish predators, such as larger predatory fish or birds.

By preying on these other predators, otters indirectly create a more favorable environment for fish reproduction and survival. With fewer predators competing for resources and preying on fish, the fish population can rebound and increase in numbers. This explains why the fish population initially increases when otters are present.

However, over time, the increased fish population attracts more otters to the water body. As the otter population grows, the predation pressure on fish increases, leading to a decline in the fish population. This decline occurs because the rate of fish predation by otters surpasses the rate of fish reproduction and growth.

Consequently, the fish population decreases until it reaches a lower equilibrium level, where the predation pressure from otters is balanced by the fish's reproductive capacity. This explains why the fish population decreases after an initial increase when otters are present.

If otters are removed from the water body, the fish population faces reduced predation pressure, allowing it to increase again. This increase occurs until the fish population reaches a higher equilibrium level, where the available resources and predation pressure from other predators limit further growth.

When otters return to the water body, the predation pressure on fish increases once again, leading to a decline in the fish population. This cycle of population fluctuations continues as otters and fish interact in the ecosystem.

Conclusion

The paradoxical relationship between otters and fish population can be explained by the complex ecological dynamics at play. While otters initially benefit the fish population by reducing other predators, their increasing numbers eventually lead to a decline in the fish population due to increased predation pressure. This cycle of population fluctuations highlights the intricate balance of predator-prey relationships in ecosystems.

Note: The information provided above is based on the available search results and may not encompass all possible explanations or studies on this topic.