I have a sinking  feeling  i should have read the rest of the day's
postings before getting  this non-boneheaded (hopefully!!) "new topic"
note composed.  Please forgive any re-dun-dan-cies, or at least shoot
privately and not in front of the madding  crowd. ouch.
  Ok, not all rivers kill,only the ones with too intimate an
assoceaition with he species Homo effluvianus, which has as its main
activity the nasty habit of dumping  as much waste of as many kinds
possible, into the aqueous media of  the planet.
I am no expert on the subject, but since you asked, river effluent has a
deleterious effect on marine life via a half-dozen ways, including :1)
chemical   toxins- recall when a waterway on the eastern seaboard of
North America caught on fire a few years back: - this river's contents
were not gently nourishing  life in the sea, at its outlet!! , 2) excess
siltation, due to erosion caused by clearcut logging, improper or
careless farming methods, etc., and 3)organic wastes of various
kinds, which cause algal blooms and other excessive plant growth, which
sinks to the bottom and rots, creating  a zone at the bottom which is
devoid of free oxygen, hence effectively dead.  An excellent example of
this
form of localized dissaster occurs around the mouth of the
Mississippi:it disgorges such a huge amount of excess nutrients, from
agriculture of
the carnivore-feeding as well  as human habitations along the way, that
thousands of square  miles of  the Gulf of Mexico becomes a huge "dead
zone" for a good portion of each year.
 
   Excessive siltation has harmed a great many coral reefs in various
parts of the world, but i do not know  many of the details this aspect
of damage done to marine habitats.  Could someone shed some  on this
subject, new as it
is??
 
 
- Ross M.
 
PS:  Apologies to the list for trying  three times to get a posting
right!!  From
now on, if it doesn't work the 1st time,  finito: no more bones,
"hubris" or hurricane seasons.