by Christina David, Mike Haydis and Tracy Paciorkowski
Seaweed, otherwise known as kelp, can be thought of as a nuisance to many people such as surfers and fisherman. However, in actuality, kelp serves a few very important functions while in the ocean. Not only does kelp act as a refugee for some animals and hunting grounds for others, but it also converts solar energy and carbon dioxide to live by using the process of photosynthesis. But the question we asked ourselves was what purpose does kelp and seaweed serve once it is washed ashore? To determine what it can do and what possible life it supports outside of the water, we conducted an experiment at Crystal Cove. On September 7 and 14, 1999, we measured kelp amounts and possible life that exists on this washed up plant.
We took four, ten-gallon white hefty bags and a meter roller as our tools. The first day we went to Crystal Cove was September 7, 1999. We started at the North end of the beach and counted one-hundred-and-sixty meters from the end of the beach towards the center of the beach using the meter roller. From there, we counted five-meter by five-meter squares in the low tide and high tide. We measured the amount of seaweed in the square and calculated an approximation of coverage by the seaweed on the sand. We then took samples of the high and low tide seaweed and put them in their own separate bags. We labeled each bag respectively, North side low tide and North side high tide. We then went to the South side of the beach and followed the same steps again. We kept these samples outside in the shade until we needed to use them for the laboratory. On September 14, 1999, we came and followed the same procedures and came home with four more bags. Both times that we went down, we began at 2:05 p.m. on the North side and at 3:05 p.m. on the South side. On September 15, 1999, we went into the Fullerton College Laboratory and took samples from each of the eight bags. We put the samples in Petrie dishes with covers until we were able to examine them. We labeled the tops of each one with masking tape so that we would not mix them up. Using an American Optical brand microscope and help from W. Sean Chamberlin Ph.D., we examined the contents of each dish for any living organisms.
The North side had approximately 75% coverage of seaweed on the low tide during our first visit (September 7, 1999). The seaweed was as high as ½ meter in the area of the low tide. The seaweed was thick and stuck together tightly. There was a large presence of sea grass (Phyllospadix) and purple-pink sea plants (corallina). While the low tide was almost completely covered, the high tide had 15% coverage by seaweed. The low tide was wet and covered in flies, while the high tide was almost completely dried out and contained a substantially smaller amount of flies on or around it. The South end was virtually untouched by seaweed. There was 8% coverage in the low tide and 5% on the high tide. The seaweed was mostly what would be considered "normal" seaweed. There was only one clump wit any corallina or Phyllospadix. The clumps in the low tide were loose and much easier to pull apart. They were slightly wet from the ocean water washing up onto them, but had begun to dry out. The seaweed in the high tide was completely dried out and covered with flies and debris (candy wrappers, grass clippings for a lawn, and a few cigarette butts). We did find three small dead man's fingers in the low tide seaweed (Codium fragile). On September 14, 1999, our second visit, the seaweed coverage was extremely different as compared to the first visit. The North low tide had 7% coverage as compared to 75% on the 7th. High tide was covered 40% by seaweed. The tide had moved 10 meters farther inland from where it was the first time we visited. The flies that had been present on our first visit were cut in half. The low tide on the North side had only two clumps of Phyllospadix in all of the seaweed we looked at. The South side of Crystal Cove had more similarities to the first observations than that of the North side. The low tide was at 15% and the high tide remained the same at 5%. The clumps looked almost identical in size and density from our first visit. The only real change on the South end of Crystal Cove was in the rise from 8% to 15% coverage in the low tide. We found no Codium fragile in the clumps on the South side. The excess debris was still present in the seaweed located in the high tide. On September 15, 1999, we studied the samples of seaweed for any forms of life. In the week 2 bag, North side high tide, we found a fly larva maggot and a water beetle. The water beetle was moving rapidly around the dish and we had to keep the lid on to prevent his escape. The larva wiggled around and was approximately ½ inch long. In week 1, North side high tide, we observed phylum bryozoa. The bryozoa was living on the leaves of the kelp. We also found this same bryozoa on the week 1, South side high tide. There was not as much located on this part, but there was a small presence. We took samples from the bottoms of the bags after not finding anything else in our first set of samples. But, unfortunately, we did not find anything else.
According to the California Beachcomber's Guide, the best times to view life are during the low tide. Amazingly, we found nothing in the low tide. Everything we found was in the high tide. The book also states that rocky intertidal sites "tend to have greater diversity of organisms that do the habitats with soft substrates. Sandy beaches tend to be less diverse, but their exposed nature allows them to collect a continuing parade of interesting wash-ups and visitors." Despite what we had hoped, the only "wash-ups" we found were trash. After reading more of the California's Beachcomber's Guide, we found some of the potential problems regarding lack of life could be due to: 1. Sediment- The sediment does not stay put, which makes it hard for anything to live on the surface or by excavating and living in a burrow. 2. Drainage- As the tide goes down, so does the water. The water leaves the sand particles and therefore dries out the sand and the burrow. This seems to happen more often when the sand grains are large. 3. Predators- Fish, crabs, worms, and some predatory snail forage are present at high tide. Birds are present at low tide. Despite these three negatives, there is a good reason that life continues to live there. The same waves that cause problems also bring in food such as carcasses and seaweed. While we did find bryozoa in the samples, it is likely that they began to grow while in the ocean, and not the beach. The bryozoa can continue to live provided that there is some sort of plankton or other organic material suspended and transported by water movement (tide changes and waves). Therefore, it is possible that the bryozoa could have begun to form and grow once the seaweed washed ashore. Something that also must be considered is the fact of varying seaweed. As can be seen from our experiment, the amounts of seaweed were not consistent. This could pose a problem for anything that is trying to live on the beach. Because what is on the beach one day can be gone tomorrow, living organisms must move frequently or be washed away. In order for the seaweed to continue to get wet and not be washed away, a good environment would be somewhere where they were in-between rocks or some sort of tide pool. Although we found little life on the samples, there are other projects that could be done to find if seaweed does play a part in supporting life on the beach. Studies of seaweed abundance and life after large storms or high strong pressure are other ways to test for seaweed's importance. Both these make for higher high tides and lower low tides, respectively. This can cause more things to be washed up and stay ashore before being washed away again. Another possible study would be to bury seaweed at points in the low tide and high tide to see if possible life could exist and flourish underneath the sand's surface. By leaving the seaweed underground for an extended period of time, it could be found whether the sand could prevent the washing away of life and it's attempts to grow through using seaweed. The last piece of information that should be added would have to be where to actually conduct the study. If the study were to be re-done, we would have measured points in the middle of Crystal Cove, and not just the North and South ends.
Oceanography 3rd Edition. By: Tom Garrison Published by: Wadsworth Publishing Company 1999
The Kelp Forest. By: Howard Hall Published by: Silver Burdett Press 1995 Beachcomber's Guide to California Marine Life. By: Thomas M. Niesen Published by: Gulf Publishing Company 1994
|Percentage of Beach Within a 165 Meters From the North Point to South Point|
|September 7,1999||September 14,1999|
|North||Low Tide||75%||North||Low Tide||7%|
|North||High Tide||15%||North||High Tide||40%|
|South||Low Tide||8%||South||Low Tide||15%|
|South||High Tide||5%||South||High Tide||5%|