I am writing an English paper wherein I have to appeal for change in the way humans treat wildlife. I was initially given a situation wherein I took a ferry in a certain area and saw a dead baby dolphin.

Along the way, I (it is written in second person) apparently notice how little water is now available for the dolphins (due to some bridge being constructed).

What exactly is bad for dolphins (or animals in general) when they have limited space to roam around?

So far I thought of dolphins hitting boats due to the crowded state of the area in question.

  • $\begingroup$ I would consider food supplies too. If you trap a population of dolphins in a small area, and they eat all the available food there, they will begin to starve if they cannot leave to get more food. $\endgroup$
    – user137
    May 5, 2015 at 13:58

1 Answer 1


The building of a bridge on a river seems like an example of habitat fragmentation. There are a number of reasons why this may be detrimental to the animals.

  • Reduced resources available. I'm not too familiar with dolphins, but all animals need food, shelter and a place to raise their young. A smaller habitat can't support as many animals due to limited resources.

  • Isolation from other habitats. The bridge may cut off the dolphins on one side of the bridge from the other side, meaning they can't mate with dolphins on the other side or migrate. The fact that dolphins on one side of the bridge can only mate with the other dolphins that share that size causes a decrease in the genetic variability on both sides of the bridge. Decreased genetic variability means an increase in inbreeding depression and reduced ability to adapt to disease and environmental changes.

  • The edge effect. This means that areas next to the edge of the habitat (i.e. next to the bridge) will be even less suitable than they were before

  • $\begingroup$ Could also be good to mention the psychological effects, especially on more social creatures like dolphins, of being in a confined area. $\endgroup$
    – Astrolamb
    Nov 16, 2018 at 20:02

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