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Related FAQs: Sources of Reef Mortality, Marine Mortality 2, Cyanide and Marine Livestock Collection,

Skip Down to Parts I, III, IV

Related Articles: Use of Marine Life as OrnamentalsCyanide Use,

/The Conscientious Aquarist Series:

Sources of Mortality on the Worlds Reefs, An Aquarist's Perspective Pt. II


By Bob Fenner


There are many other groups, like these Bryozoans (Moss Animals) shown here that are principally filter feeders as well. To a large extent dependent on sex cells and larval forms for nutrition.
The Whale and Basking Shark, Manta Rays... all filter feeders. Think of the most intensely fished species of schooling fishes: herrings, menhaden, anchovies... all filter feeders at least as young. There are even slime-filter feeders like some of the Parrotfishes and Wrasses, that collect food items on their sleeping cocoons, ingesting it on wakening for nutrition.
This is certainly not an exhaustive list, though the principal sources of mortality in the seas are listed.
My fave example, indeed, the ONE I was going to make my entire pitch, has to do with Parrotfishes, family Scaridae, and their role as producers of coral sand... Though not all species feed directly on live coral polyps, one can calculate of the populations of those that do to some extent, energetics of their consumption patterns that a good one to two million tons of such sand is produced, eliminated through the scarids in the course of a year of their chewing.
Overgrowing to gain advantage of using available light, digestive dominance are observable elements of competition between stinging-celled animals. To what extent does such competitive behavior, chemical and physical impugn other individuals and species ability to survive?
The role of "living together" (symbioses) from seeming mutualism to commensalism to degrees of parasitism is just beginning to get due consideration as direction and pressure in evolution, let alone the effects of outright infection, infestation by parasites and infectious agents. Yes, your livestock encounter the same sorts of complaints in the wild as in your aquariums. Here is shown a "Black Spot" Paravortex worm, lymph on a Queen Angel, and crypt on a tang.
Storms can be a tremendous source of reef damage and outright mortality. The many tons of dust blown off from northern African deserts has been implicated on deaths/bleaching of corals of the tropical West Atlantic...

Another pleasing example might be the seas between Viti Levu and Vanua Levu in Fiji... Have been there, witnessed a good part of the reef flat exposed by a cyclonic storm.

Cumulative genetic defects with time, replication take their toll in the wild. Though it seems rare (most all "old", sick, less able organisms seem to perish by "red tooth and claw") there are a few times I have seen obviously "old age" at work in the end of marine lives.
Though relative to our experience, life spans this doesn't seem to be a large source of mortality, there are obvious cases where geological events have produced spectacular losses of life. Here is an example, the Sinai Peninsula in the upper Red Sea... the cliffs behind are made up of coral reefs that have been pushed up eons past. Florida could be used as another example.
Many human activities are of consequence in ending, changing which life forms are favored in altered environments. Some of these sources of mortality that are profligate are little discussed. Here I've listed (and will give examples) of the principal categories.

As you will find, the hobby use of wild-collected stocks is relatively tiny.

Sessile invertebrates, algae can't "get away" when activity on neighboring land rains down soil and other solids. The best documented account are the siltation and fertilization effects of the Mississippi on the Gulf of Mexico.

 Another one: Near Nadi, Fiji to the Harbor at Latouka. Some 21 kilometers by 500 feet or so of "reclaimed land" to be filled in seaward...

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