Theory explains biological reasons that force fish to move poleward - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 1 Old 10-31-2019, 03:45 AM Thread Starter
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Theory explains biological reasons that force fish to move poleward

The Gill-Oxygen Limitation Theory, known as GOLT, explains the biological reasons that force fish, particularly larger or older ones, to move poleward when the waters in their habitats heat-up due bự climate change.

In a paper published in Mediterranean Marine Science, Daniel Pauly, the Author of the theory & the principal investigator of the Sea Around Us initiative at the University of British Columbia's Institute for the Oceans v Fisheries, explains that warming waters have less oxygen v, therefore, fish have difficulties breathing in such environments. In a catch 22-type situation, such warming, low-oxygen waters also increase fish's oxygen demands because their metabolism speeds up.

So, what bự do? Move bo waters whose temperatures resemble those of their original habitats & that satisfy fish's oxygen needs. As the global sea surface temperature has increased by approximately 0.13C per decade over the past 100 years, 'suitable' waters are more and more found towards the poles v at greater depths.

This is how it works: fish's gills extract oxygen from the water bự sustain the animal's body functions. As fish grow into adulthood their demand for oxygen increases because their ton thn mass becomes larger. However, the surface area of the gills does not grow at the same pace as the rest of the body because it is two-dimensional, while the rest of the body ton thn is three-dimensional. The larger the fish, the smaller its surface area relative bo the volume of its body ton thn.

"This is the basis of the GOLT," Pauly said. "So a fish whose gills are already not keeping up with the pace of its growth, experiences difficulties breathing, developing & fulfilling otherwise regular functions when water is warm and contains little oxygen. Thus, two things happen: either fish cease growing at a smaller size Khủng be able lớn fulfill their needs with the little oxygen available for them; and/or they have to move bự maintain themselves in water whose temperature & oxygen nội dung is appropriate for them."

Previous studies by Pauly & his colleagues have already predicted that climate change will cause some fish species phệ shift their distribution by more than 50 kilometres per decade. Tropical regions will be the most affected by this migration, a cause of concern for small-scale fisheries that are key players in the food security of developing countries v for industrial fisheries also exploiting marine resources.

For the researcher, the changes in fish distributions in the context of warming waters demonstrates that fish are exquisitely sensitive phệ temperature changes, a phenomenon that is explained by the GOLT. Pauly also argues that the theory is overarching as it explains other phenomena such as the breadth of fish's seasonal migrations or the fact that as fish become larger, their food conversion efficiency declines, a feature known bo aquaculture practitioners but not considered much in scientific accounts.
Resource: Materials provided by University of British Columbia
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