Frontiers of Science: Backyard Ocean Finally Full of Fins!

“Frontiers of Science: Backyard Ocean Finally Full of Fins!” Friend, Mar. 1982, 17

Frontiers of Science:

Backyard Ocean Finally Full of Fins!

Last month I described how my family and I constructed a 4,000-gallon pond in our backyard. Although all of the experts we consulted told us we should maintain it as a freshwater system, we were determined to convert it into one containing salt water. When we could see that our water system was operating properly, we ordered over a thousand pounds of synthetic sea salts from a company in Cleveland, Ohio, and added them to the water.

As you remember, we had previously stocked our pond with fifty black mollies we had purchased from a tropical fish store. Fortunately, these fish are able to live in both fresh and salt water, so they survived the conversion process. Of course the freshwater algae died, as did most of the aquatic insects that had begun to invade the water; but that was expected. Now with everything in order, we geared up for our first collecting trip that was designed to start our pond on its way to becoming a true marine ecosystem.

The place we chose to visit was the Gulf of California near Puerto Peñasco, Mexico. Our family had vacationed there before, and it was only about a six-hour drive from our home. In addition, at times of new and full moon the tides at Puerto Penasco are so extreme that the water surface fluctuates over 20 feet up and down twice daily, alternately exposing and covering a rocky reef several hundred yards out from shore. At low tide it is actually possible to wade out to this reef, where one can find a number of creatures usually not seen on the beach.

Our first trip was a two-nighter, and we had the good fortune to collect a wide variety of life forms and get most of them back alive. Included in our catch were about a dozen different species of fish, several different types of sea star, a diverse assortment of crabs, shrimp, clams, snails and barnacles, and some sea hares.

We brought our collection home in ordinary Styrofoam ice chests. To help the creatures survive the trip, we turned the car air conditioner on full blast to keep the water as cool as possible. Low temperatures reduce animals’ activity rates and decrease their need for oxygen. But we still added some oxygen to the water by means of battery-operated bubblers.

In addition to collecting specimens to add to our pond, we also collected data on sea surface and beach temperatures, so as to increase our knowledge of the best method of operating the pond’s temperature control system. To do this, we used an infrared thermometer that gave us the temperature measurements we sought by merely pointing the instrument’s heat radiation sensor at either the land or the water.

As soon as we arrived home, we added our catch to the pond. Normally, we would have taken an hour or two to get the creatures used to their new water; but after traveling so long with such a small volume of water, we felt it best to get them into the “fresh” salt water as soon as possible.

Much to our delight, everything survived and has continued to prosper to this day—except for those creatures that have served as food for others. Our bullseye puffers, for instance, ate the barnacles and sea hares, and our larger crabs devoured a lot of clams and snails as well as each other! Now, however, even they are beginning to disappear; for on our last trip, we brought home an octopus, and crab meat is a temptation he just can’t resist.

At the time of this writing, we have made three collecting trips, each of which has netted us different types of sea life. Our second time out, for instance, we caught about a hundred small grunion that swim about out pond in their own private school. Their numbers have gradually decreased, however, for two large flounders and some sea bass that inhabit the pond help themselves to a few grunions whenever we forget to feed the larger fish their daily ration of freshwater minnows.

At this point, we feel that we have accomplished most of what we set out to do. In spite of all of the reasons everyone offered as to why we could not establish a salt water ecosystem in our backyard, we have done so.

Our efforts are now directed toward studying it and learning all we can about its physics, chemistry, and biology. Twice daily we measure water temperatures at eleven different places in the pond, along with air temperature and humidity. This is done just after sunrise, when it is coolest, and late in the afternoon, when temperatures are generally at their maximum. We also keep notes on biological events of interest, such as the spawning of sea hares and some of the fish.

In time, the data gathered will serve as a basis for science fair projects as well as for scientific articles that we will write on these subjects. We have even formed our own research corporation to study these and other aspects of the world around us and have embarked on a great family adventure that is truly a new frontier for our family. And more than ever before we appreciate our Heavenly Father’s plan for family associations.

Photographed by Dr. Sherwood B. Idso

1. Lance, Craig, and Keith display the thousand pounds of sea salts that we added to the pond to transform it into a mini-ocean.

2. Keith and a friend work our 20-foot minnow net in a finger of the sea near Puerto Peñasco, Mexico. Oftentimes they would trap large schools of grunion this way.

3. Some of the fish we brought back were actually caught with fishing poles, such as this puffer. If they were only hooked through the lip, we carefully removed the hook and they still lived.

4. At low tide, rocky reefs were exposed. The boys crawled all over them, finding a great variety of creatures among the nooks and crannies.

5. All of the marine life we caught were kept in Styrofoam ice chests or food coolers, into which we bubbled air from a battery-powered pump.

6. Keith displays a handful of oysters dug from the reef.

7. Back at home we introduced our catch to the pond.

8. The bullseye puffer enjoyed watching us through the observation room glass as much as we enjoyed watching him!

9. In the ocean this crab tried its best to escape; but in our pond it begs for food.

10. A view of our tidal pool, with several sea anemones.

11. It’s easy to see the starfish and snail in this view of the shallow end of the pond. But can you see the flounder that has wriggled itself partway down into the sand to camouflage itself?

12. At night our octopus roams the pond. In this flash of light we caught him “jetting” over one of the anemones.