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Sunday, September 17, 2017

World's Fish Decreasing In Size and In Numbers

Overfishing has caused population collapses of certain fish species, and ocean acidification is already causing difficulties in the oceanic micro-species based food web. Now, it appears that "warming temperatures and loss of oxygen in the sea is shrinking hundreds of fish species—from tunas and groupers to salmon, thresher sharks, haddock and cod—even more than previously thought."

"Because warmer seas speed up their metabolisms, fish, squid and other water-breathing creatures will need to draw more oxyen from the ocean. At the same time, warming seas are already reducing the availability of oxygen in many parts of the sea.... and since the bodies of fish grow faster than their gills, these animals eventually will reach a point where they can't get enough oxygen to sustain normal growth... the body size of fish decreases by 20 to 30 perent for every 1 degree Celsius increase in water temperature."

"These changes will have a further profound impact on many marine food webs, upending predator-prey relationships in ways that are hard to predict. Lab experiments have shown that it's always the large species that will become stressed first. Small species have an advantage, respiration-wise."

http://news.nationalgeographic.com/2017/08/climate-change-study-ocean-fish-size/

http://www.wral.com/biologists-concerned-about-juvenile-fish-in-gulf-of-mexico/16918381/

As water warms, it is less able to retain gases such as CO2. Thus, as Milankovitch cycles (orbital variations around the sun) cause the Earth to become warmer, the oceans are less able to absorb atmospheric carbon dioxide. 
Note: Oxygen is, also, a gas.

Related reading:
Mountain Goats Shrinking In Size
http://news.nationalgeographic.com/news/2014/10/141022-chamois-mountain-goats-shrinking-climate-change-global-warming/

Question: Will becoming smaller become beneficial for humans in the future?


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