Spatial position of eggs within an egg-clutch has an effect on embryonic development in clownfish

What is it about?

Since the size of newly hatched larval fish is directly related to egg size, small differences in initial egg size can be critical to survival and further development of offspring. Larger size at an earlier age means competitive advantage, higher probability of survival. In this study we investigated whether the spatial position of an individual egg within a clutch affects size variation in two different clownfish species. We analysed egg growth metrics, protein content and the activities of the key metabolic enzymes. We found that the position in the egg clutch determines the quality of the hatched larvae. A major reason for this is the oxygen supply to the eggs – as simple diffusion is not sufficient.

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Photo by David Clode on Unsplash

Photo by David Clode on Unsplash

Why is it important?

In nature the mortality of fish eggs and larvae is very high, in clownfish up to 90%. Breeding of clownfish in captivity still leads to a certain degree of mortality of larvae during their first days of life. For the ornamental trade it is highly valuable if the mortality in bred specimens can be lowered significantly. Increased survival rates can be achieved through better oxygen supply of the eggs and less probability of fouling.

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