AHABS... Issue Twelve
Ronald L. Shimek, Ph. D.
More Bad News
As I was scanning the news this morning, 8 August, 2007, I came across a link to this article:
Bruno J. F., and E. R. Selig . (2007) Regional Decline of Coral Cover in the Indo-Pacific: Timing, Extent, and Subregional Comparisons . PLoS ONE 2(8): e711. doi:10.1371/journal.pone.0000711
The authors have plotted the demise of coral reefs, specifically the amount of area actually covered by coral on these “coral reefs” since the mid-1960s and, not surprisingly, it is dropping like the proverbial stone.
The average drop is something like a 1.5% drop in cumulative coral cover per year, since 1968. Plot it out for yourselves. Some of you will probably be still alive when the last “coral reef” ecologist goes out on the last field trip to make the last survey, after which that person will conclude that it is fruitless to do any more surveys, there isn't enough left to worry about.
What does somebody have to do to wake up the majority of the people in the world that said world is being so severely trashed it will be impossible to live on before long? It was Tip O'Neill, a former speaker of the U. S. House of Representatives who, I believe, coined the phrase, that “All politics is local.” I suppose that also means that all concern about the environment is local, and given the situation in the world today, that being that reefs are not really local to any person, reefs are doomed. After all, all reefs are underwater. No matter what happens to them, it is invisible. Even to those people living next to them, they are a foreign place - not something that is theirs to worry about.
And, gee, after all, what can they do?
Indeed, what can any of us do? I suppose, realistically, nothing. I have been trying to raise the awareness of this problem to hobbyists in my speaking presentations for several years now, and while I sometimes seem to reach a person or two, most hobbyists simply don't seem to care. I suppose this may indicate something of the effectiveness of my presentations. I think it also indicates the depth of concern for the environment amongst hobbyists...
Feeding Reef Aquarium Invertebrates
Ronald L. Shimek, Ph. D.
The Need to Feed
I generally start my invertebrate zoology classes with a series of six basic mechanistic questions, listed below. The first two questions refer any anatomical structure, the last four to the organism in general.
1) How does work?
2) Why is it needed?
3) What does eat?
4) What eats it?
5) How does it get and process information?
6) How does it reproduce?
These are the same questions that aquarists should ask themselves about the organisms that they keep. If the aquarist can answer these questions reasonably well, and adjusts her or his care accordingly, keeping animals in prime condition is an easy task.
Not all of these questions are of equivalent importance. The questions about the specific structures may, if answered, provide much useful information. However, it is really unnecessary in many cases to know HOW a structure works or WHY it is needed. It really does suffice to say that it IS needed and DOES work. Similarly, from the aspect of an aquarist trying to keep some kidnapped animal alive, HOW an organism senses the environment and processes this information is often immaterial.
ON THE OTHER HAND, IT IS ABSOLUTELY IMPERATIVE TO KNOW THE ANSWER TO QUESTION NUMBER THREE: “WHAT DOES IT EAT ?”
All animals NEED to feed. In the parlance of Star Trek's Starfleet , obtaining food is their “prime directive.” Without sufficient food, ALL other activities of the organism cease and it dies. Within the context of this essay, it is probably best to define what food is. As with all terms that “everybody knows” there is a great deal of ambiguity about this term...
Nassarius Snails as Scavengers in Reef Aquaria
Ronald L. Shimek
One of the continuing problems of marine reef aquarium husbandry is how to deal with feeding. Initially, and still, in many places in the hobby, the need of animals such as corals for food was essentially ignored. The prevailing opinion, based wholly on inaccurate conjecture, was that corals did not need to feed, as they had their own internal food producing organisms in the form of endosymbiotic algae called zooxanthellae. As result of this starvation philosophy a large number of really very hardy animals were labeled hard to keep and condemned to a slow death by starvation.
Over the last several years, most hobbyists have awakened to the need to feed their animals. Examination of the pertinent literature by scientists studying coral reefs confirms that an absolutely prodigious amount of food flows on to and over a coral reef in a day. Most of this food is intercepted and eaten by the reef animals, not least of which are the corals themselves. Small-polyped corals, in particular, are adapted for - and require - an essentially continuous bath of small particulate planktonic food to remain in good health. In a reef aquarium with a decent sand bed containing a good sand bed fauna, a sizeable component of those needs may be met by production of bacterial aggregates, larvae, and other microplankton generated by the bed.
However, to generate those small planktonic items, the sand bed, or rather the organisms in the sand bed, needs to obtain nutrition. Additionally, this sand bed planktonic production is only one source of the food for many of the animals in the aquarium. The other source would be, of course, food added by the aquarist. The volume of this added food may be relatively large, some hobbyists now feed relatively well; particularly since it has become apparent just how much food is necessary for good health of the animals.
This food is often particulate in nature and once added, it rapidly disperses throughout the aquarium. Not all of it can or will be eaten immediately. The excess settles out of the water mass to the bottom of the aquarium. Such uneaten food is nutrient-rich and if it stays on the bottom, it will release a significant amount of that nutrient back into the water as it breaks down due to chemical and bacterial factors. In turn, such dissolved nutrient will fuel algal and cyanobacterial blooms; additionally, it will adversely effect the metabolism of many animals including corals and soft corals.
Ideally, this uneaten food would be rapidly found by an animal that scavenges food. That scavenger eats it, incorporates part of it into its own tissue, excretes part of it as dissolved gas and waste, and passes the rest down a food chain as feces and detritus. At each succeeding level in the food chain, there is less and less useable material of the original uneaten food particle left,...