WE GROW MORE AS A CLOSE FAMILY
How coral reef fish group size and habitat influence growth
Graduate Student: Jessica Nielson
Jessica is interested in understanding
how coral reef fish populations are affected by the size of their family
and the amount of available habitat.
Jessica is studying the
threespot damselfish, Dascyllus trimaculatus, which are planktivorous
fish that make their home on sea anemones. The relationship between
threespot damselfish and their anemone is called a mutualism. The fish
rely on the anemone for protection from predators and in return, the
fish gives the anemones nutrients. Jessica experimented with different
numbers of fish on different sized anemone habitats and observed how
quickly each fish grew and how vulnerable they were to predation by
bigger fish based on their family size and how much space they shared
on the anemone. She also used underwater video cameras to look for
interesting patterns in their feeding behavior. This type of fish eats
plankton, which are tiny animals that drift with currents in the ocean.
When she watched the videos, Jessica measured how often and how quickly
the fish ate, how much they fought with their family members, how brave
they were and how far each fish was willing to swim away from the anemone's
shelter for food.
Results from Jessica's experiment show that fish that live in
larger families on a small anemone home grow more than small families living on
a big home. This is because they spend less time chasing each other and are brave
enough to swim far from their anemone for their favorite food. However, there is a
tradeoff, because since they are brave enough to swim away from home, they are also more in danger
of being eaten by bigger fish.
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