Whats Killing all of the Fish?








On Friday, August 31st, 2012, people on the shore of Lake Erie,
between Rondeau Park and Port Stanley awoke to a manure-like stench,
issuing from the lake. From Duttona Beach, Clearville Port Stanley and
Rondeau, reports of a bad smell, brown water and dead and dying fish
began to come into the Windsor and London offices of the Ontario
Ministry of the Environment. This reports continued throughout the
weekend.

This turned out to be only the beginning of the largest die off of
near shore fish in recent history. The beaches are littered, and in
some cases, covered with tens of thousands of rotting fish. Species
found included Carp, Sheephead, Yellow Perch, Lake Erie Catfish,
Suckerfish, Smelt, Whitefish and Minnows. All these near-shore species

appeared to have died within a short period. From Port Glascow an
offshore fishermans report of gasping fish and the suddenness of death
resembles hypoxia, the reduction of oxygen in the water.

Hypoxia can have a number of causes including an upwelling of oxygen
poor water, excessive nitrogen or by, eutrophication, the depletion of
oxygen by decaying organic matter.

Unlike last year, there is at present, no evidence of the blue-green
algae, microcystis, that painted the water a sickly green. The Windsor
branch of the Ministry of the Environment has received no reports of a
major spill. An effect of this magnitude, spread over such a large
area must be seen from a more aerial perspective.

From the NOAA, CoastWatch website:



http://coastwatch.glerl.noaa.gov/modis/modis.cgi/modis?region=e&page=2


…can be seen the emergence and dissipation of a large gyre, off of
Point Aux Pins, Rondeau. The gyre was not visible on August 27th and
appeared during the time of the initial reports of bad smells and dead
fish.

Is it possible that a large blob of oxygen depleted water, from the
Western Basin of Lake Erie has made it way Eastward, killing inshore
fish?

When bottom sediments are disturbed, sulphur loving anerobic bateria
and their waste products are suddenly released into the aquatic
environment, changing both the temperature and chemistry of the water.

Were such an event to occur over a large area, and that cold, oxygen
starved water were to travel westward, it could result in poor mixing
with the warmer surrounding waters. The best way to determine the
cause of any such event is to have a boat ready to collect samples.

The Ministry of the Environment has sent Area Environment Officers to
collect surface water samples and the Ministry of Natural Resources
has collected fish for forensic study. Sadly, our provincial Ministry
of the Environment doesn’t have the funding to purchase a small boat,
that would allow for accurate dissolved oxygen readings beyond the
surf zone.

If this event proves to be from a non-point source, that is, a source
from the lake itself, then we may have a very serious problem with
repeats of this effect in the future. The bottom of the Western Basin
has been dubbed the Lake Erie “Dead Zone” for good reason. Decades of
nutrient runoff from the Detroit river, cities on both sides of the
lake and surrounding agribusiness, have contributed to a massive layer
of sludge at the bottom of the lake. If this sludge begins to mobilize
due to environmental temperature effects or excessive methane buildup
during the hot summer months, then we may be witnessing the creeping
fingers of the Dead Zone extending throughout the lake.



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