“Water Temperature Effects on Fish and Aquatic Life”

Today I found this little piece of information in my personal "archives". It was probably the first ever assignment submitted at the beginning of my professional studies. Its fascinating how human knowledge grows over time..........

"Changes in temperature affect aquatic life. Temperature determines which organisms will thrive and which will diminish in numbers and size. For each organism there is a thermal death point. Also there is a range of temperature of that produces optimal abundance. Climate change is a cause of increasing concern to scientists and it will have decisive effects on marine mammals. How climate change will affect the ocean, which is home to marine mammals, is hard to predict since there are many factors that affect ocean ecosystems but here my emphasis will be on the effect of rise in temperature on “whales”. Long time ago, due to environmental changes, Marine mammals evolved to live in the ocean, but the effects of climate change may be altering their habitat more rapidly than they can adapt to the changes.

·         What is climate change?

A change in climate that persists over a sustained period of time is termed as the climatic change. Climate change includes increases in global surface temperature i.e.. “GLOBAL WARMING”. This results in change of weather events (extreme weather events like rainfall)

·         Why change in climate (Global warming) takes place?

The   main cause of climate change is due to rise in the following components in the atmosphere.

         i.            of carbon dioxide

       ii.            other greenhouse gases

These gases are increasing in the quantity mainly due to two reasons:

•          i.            Sun’s output
•        ii.            Human activities

Effect of climate change can results in  the growth, toxicity, and distribution of harmful algal blooms. These algal blooms have serious effects on not only marine ecosystems, killing sea animals and fish with their toxins.

• Changes in the water bodies due to climate change:

During the last century, global average land and sea surface temperature has increased dramatically. Approximately 30% of the ocean warming over the past decade has occurred in the deeper oceans below 700 meters. Now, this change in climate can have very diverse effects on the marine life as many species (marine) require specific temperature ranges in which they must live. Each organism must be favored by the proper temperature if the individual or its population is going to survive.

Increased water temperature is an important consideration when toxic substances are present in water. Not all the animals present in water are capable of maintaining their bodies, their mood of nutrition, reproduction etc according to the past pace of changing environment.

v  WHALES:

According to “Mark Simmonds” International Director of Science at WCDS:

“Whales do have some capacity to adapt to their changing environment, but the climate is now changing at such a fast pace that it is unclear to what extent whales and will be able to adjust, and we believe many populations to be very vulnerable to predicted changes.”

Climate change impacts are currently greatest in the Arctic and the Antarctic. According to the reports, those cetaceans that rely on polar, icy waters for their habitat and food resources are likely to be dramatically affected by the reduction of sea ice cover.

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·         Reproduction:

Under normal circumstances, a female right whale requires three years between births. But if a calf aborts or dies, a female need two years to recover, and the interval expands to five years but over the passage of time. five-year calving intervals  can explain these two years of recovery but this evidence does not suggest that whales are failing to get pregnant, rather , the thing which has been observed is that unborn and newborn calves are not surviving.

REASON:

The reduced availability of krill during the summer feeding season is causing pregnant mothers to abort and calves to die.

How decrease in polar ice caps effect Wales?

As sea ice cover decreases there will be more human activities i.e. shipping, exploration, commercial and military activities etc.

Examples:

Belugas, narwhal, and bowhead whales are being mainly affected by climatic changes.

o   BELUGA WHALE:

o   Occurrence:

o   The beluga whales are also known as the “white whales” .

o   Their scientific name is “Delphinapterus leuca.” It is mostly found in Arctic and sub-Arctic  cetacean.

o  Endangered:

o   The beluga has been listed as "near threatened" by the IUCN due to uncertainty about threats to their numbers in Russian Arctic. The most serious impacts of climate change on Belugas may not come directly from          the effects of weather conditions, but rather indirectly from the role that regional warming and reduced sea ice play in changing human activities

o   It has also made difficult for them to prey.

NARWHAL WHALES:

o   It is medium-sized toothed whale.

o   It is found in the Arctic region.

o   They are one of the most sensitive Arctic marine mammals to climate change.

o   Sometimes tribes or narwhals get trapped in ice due to the sudden changes, may get stuck in ice may be, later on hunted by humans.

BOWHEADED WHALES:

o   The bowhead whale is a baleen whale.

o   It lives in fertile Arctic and sub-Arctic waters and doesn’t migrate to other regions to feed or reproduce.

o   Decreases in ice extent will be more of an indirect effect than actual loss of habitat for them.

RESULT:

Many projects are being run by WWF under IWC (international whale commission) for their protection, removing threats and for their survival. Government of concerned countries are working to reduce their hunting and the fixation of industrial wastes before their  disposal in the oceans.