It is predicted that ocean temperatures in the tropics will rise to more than 30 degrees Celsius in the future. When this happens, it is the shallow coastal areas that will be mostly affected.
Most species of hard corals will bleach and eventually die, and many species of fish and reef-associated invertebrates will disappear, either by dying or by migrating to cooler parts of oceans.
Some species may simply adapt to an environment with higher temperatures.
At present, it is a common observation that coral reefs have been known to suffer from bleaching during episodes of ocean warming, which are predicted to occur more frequently in the near future.
One good thing, however, is that deeper portions of oceans may not be exposed to higher temperatures compared to shallow waters.
Such cooler water, especially with oceanic currents, may serve as refuges for some species of carnivorous fish, such as carangids and deep-sea lutjanids.
Since these groups of species are at present frequently taken by fishermen using traps set at 150-200 feet or even in much deeper sea water, they probably occur at various depths of oceans.
Scuba divers have reported the presence of carnivorous fish species at a depth of 150 feet, the limits of conventional scuba diving.
It is, therefore, probable that these deep-sea fishes are more likely to survive, given the much cooler, deeper waters of oceans.
Studies of deeper oceanic waters need to be studied for marine species found at these depths. Marine protected areas (MPAs) should include these habitats.
This is emphasized because most MPAs at present are in shallow waters, where they are at risk and exposed to high temperatures, and the typhoons trending to hit the Philippines at lower latitudes (such as typhoons Sendong and Pablo which devastated the southern coral reefs).
It is time to focus on ocean habitats in deeper water, and to declare some of these areas as no-take MPAs.
For studies at greater ocean depths, it is probably necessary to use tools that facilitate observations of these habitats.
Although these tools are costly, they are worth acquiring to enable marine biologists to enlarge our knowledge of deeper seas within the Philippines.
One of the results of deep-sea studies is the new metric labelled by Dr. Daniel Pauly as “temperature of the catch”.
This metric describes the changed composition of fish catch in deeper oceans, resulting from changes in water temperatures.
This new metric is an evidence for the changing temperatures in oceans.
One of the future directions in marine research is the inclusion of studies on the deeper portions of oceans and seas to discover what species are found there and the nature of their habitats.
Marine technology has advanced with the development and deployment of submersibles for deep-sea studies which could be useful for research in our waters.
Those species with wide ranges of vertical distribution in oceans could be sources of recruits for shallower marine areas in the event that the present species in the latter areas fail to adapt and survive in the face of global warming.
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Author’s email: suakcrem@yahoo.com
