JDavid;873998 wrote: http://www.ronshimek.com/salinity_temperature.html">http://www.ronshimek.com/salinity_temperature.html</a>[/QUOTE]
^Read!! Full of information, sources cited, not too complicated. When I set up my for real reef tank, I'm going to make sure that all the animals have the same optimal conditions so that they can thrive equally.
An excerpt:
[QUOTE=]Many reef aquaria are set up and maintained in a manner that continually stresses the organisms in them. In general, these stresses are not enough to kill the animals outright, but often the environment is sufficiently unhealthy that the organisms are continually on the edge of disaster. This is probably the reason that many reef animals are considered to be delicate. Most animals, including reef organisms, if maintained with proper basic care and conditions are very resilient and actually are rather hard to kill. This is particularly true of sponges, sea anemones, corals, and most other invertebrates. Nonetheless these groups have the unjustified reputation of being hard to keep.
Unfortunately, it is the poor practices of aquarists that are to blame for the substantial mortality witnessed in many systems. For many years, research scientists have maintained and grown many of these so-called delicate organisms in aquaria, sometimes in flow-through systems, but much more often in closed systems similar or identical to those used by most hobbyists. These scientists are often quite successful at getting the animals to grown, spawn, and reproduce. Yet, in the reef aquarium community, those same animals have the reputation for being difficult to maintain. What is the reason for the difference between research and hobby situations that allows more success for the researcher?
The primary reason for the laboratory success is that researchers tend to set the conditions of their systems as near as possible to the physiological optima of the organisms they are raising. Having raised and kept invertebrates for over 20 years in research systems that were more-or-less typical, I can vouch for the fact that scientists are just as sloppy and lazy as everybody else. They want to spend their time doing just about anything except working to culture animals, so they often arrange their systems to minimize maintenance. The major basic rule of thumb in keeping animals easily is: "Find out what the animal's physiological optimum temperature and salinity ranges are, and adjust conditions to match those optima." While this rule should seem obvious, it is violated by many reef aquarists. Both the temperature and salinity of many reef aquaria are kept near or even somewhat below the lower normal survival limit of physiological tolerance for many of the common animals. This results in substantial and unnecessary mortality. In effect, these mini-reef systems keep the animals just healthy enough that they die slowly.
Some Final Thoughts
The array of new and different organisms becoming available for the mini-reef hobby is due to the biological mining of the areas near the centers of distribution. This is, after all, where the diversity of organisms is greatest. In most cases, we do not know the specific physiological tolerances of these animals. Successful conditions for maintenance, however, can be determined by finding the conditions at the center of the species' distribution. Additionally, there is another rule of thumb that can be applied here. Fresh water is less dense than sea water, and as water stratifies by density, rainfall and diluted sea water tend to float on sea water, and with relatively little mixing at the boundary. Consequently, reef animals from shallower areas (less than 33 ft (10m)) have to be tolerant of lower salinities and can withstand them much better than those from deeper waters. Unfortunately, many common corals or coral reef animals offered in the hobby are now being collected from depths in excess of 100 ft (30 m) and these animals are far less tolerant of inappropriate salinities.
Figure 5. A storm in Chuuk (Truk) Lagoon, September, 1984. Many coral reef areas receive more than 2.5 m (100 inches) of rainfall annually. This means surface waters, down to 10 m (33 ft) or more often have significant and fluctuations in salinity. Most shallow water coral reef organisms are tolerant of transitory and minor changes in salinity.
We often try to maintain a constant environment in mini-reef systems and trust that such an environment will provide the appropriate conditions for organism survival and growth. Constancy of conditions, however, is not particularly important if those constant conditions are wrong. Additionally, fluctuations in the reef system environment are of no concern as long as the fluctuations are not so extreme as to exceed the animals' tolerances. Temperature in lagoonal environments often varies as much as ± 18 ° F (10 ° C) per day around an average value. That average value, however, is often close to the physiological optimum of the species present. While hobbyists should try to maintain the average conditions in their captive environments near the physiological optimum for the organisms involved, fluctuations in temperature and salinity will not cause problems as long as they are within the tolerances of the species involved.
Maintenance of the reef system at optimal conditions is not without problems. Invertebrates maintained near the lower limits of their physiological ranges metabolize and live very slowly compared to normal. This can have its advantages; a dying animal will look good for several weeks or months, and still be effectively dead. It is metabolizing very slowly and, in effect, is almost in a state of suspended animation. Corals, particularly, under these conditions seldom need to feed, and may not even have enough energy to feed. They subsist on their stored energy reserves and byproducts of their endosymbiotic algae, which under normal situations provide nowhere near enough nutrition for adequate growth. Additionally at these low temperatures, the zooxanthellae are also producing significantly less nutrition than they would be doing at higher temperatures (Coles and Jokiel. 1977; Goiran, et al., 1996; Leletkin, et al., 1996;). Coral growth is effectively minimal, and will be hard to detect (Goreau and Goreau, 1959; Goreau, 1961; Goreau, 1977ab; Houck et al., 1977; Highsmith 1979). Additionally, the animals may repair injuries too slowly to prevent infection. After they use the last of their stored reserves, they will die slowly. Of course, they will still be around to enjoy for a period of a few weeks.
Animals maintained near their physiological optimum will need to be fed regularly and adequately for growth. As an example, I maintained a small Heliofungia for an 11 month period during which time it almost tripled in diameter. It was fed the equivalent of 1 to 2 feeder goldfish per day. It eventually succumbed to damage from a predator inadvertently placed in my tank, but was growing and thriving prior to that time.
At normal (for the organism, not the aquarist) temperatures and light conditions, to assume that corals and other animals can get full nutrition from their endosymbionts is to insure that they will not survive (Sorokin, 1990a,b; 1991; For an excellent in-depth and fully referenced treatment of foods and feeding see: Borneman, 2002 -2003 = 1 , 2 , 3 , 4 , 5 , 6 , 7 ). They will need to be fed or the light intensity increased well beyond the normal range for the organisms. Unfortunately, few of these animals are generalist feeders and their survival will depend upon finding an adequate and appropriate diet. Other reef inhabitants will need to be fed more frequently as well. This provides a continuing challenge, but the variety of foods on the market today generally makes finding an acceptable food not too difficult.
Finally, there is the very real problem of the mixed fauna and flora found in many of our systems. Aquarists tend to mix animals from different geographical areas with joyous abandon. This results in a tank full of animals with a variety of ranges of tolerance depending on whether the animal was from the very warm waters of Indonesia or the cool subtropical waters of the northern Gulf of Mexico. A modification an old saying would apply here. As a "Jack of all trades is a master of none," generalized conditions are not good for any tank inhabitant. Maintaining a tank in upper 70 degree F range (24-26 degrees C), will stress any reef inhabitants from the central Indo-Pacific as it is too cold, and as this is near the upper limits for subtropical organisms it will stress them as well. It would be better for all concerned, if aquarists concentrated their efforts in maintaining separate systems for organisms from geographically disparate areas.[/QUOTE]
