Associated Effects of Beach Grooming on Intertidal Organisms - Essay Example

Associated Effects of Beach Grooming on Intertidal Organisms By For March 23, 2006 A public beach is the battleground between those wanting to conserve the intertidal organism communities from reckless endangerment and those who feel that their needs should are more important for accessing the beaches for their various seaside activities. There are three goals associated with this paper which include: quantifying the pattern of zonation in sandy beach intertidal organisms, compare density and species diversity in portions of beach that are groomed or not, and, measuring the association of sandy beach invertebrates and kelp wrack. Introduction The importance of measuring the macrofauna that is evident inside large kelp wracks ensures the survival or extinction of many species that flourish within the macrofauna community. Such specimens as hopper, work+Poly and crab are the subject of this paper and their capacity to flourish in numbers in either a groomed or ungroomed sandy beach. The kelp wracks provide an immense macro- and micro-organism breading ground along with sustainable features necessary to fulfill their existence. These numbers were inputted via t-test and produced outputs for their mean variance and their percentages equivalent to the groomed and ungroomed beach. Methods The first of two samples was taken in the early morning prior to any grooming and a second sample was completed in the early afternoon along the transects that ran perpendicular to the line formed by the water's edge. Each sample consisted of a shovel full of sand and the organisms in it. The sand was then sieved in order to count all the organisms in each of the samples and was recorded on the data sheet. The t-tests and analysis/graphs are at the end of this report. There was some wrack present in the first sample and very little in the second sample. The transect continued on for the prescribed 30m long zone and 5m shoreward of the berm and was run down towards the water. Each sample was taken at every 2-meter transect line and to preserve the area after testing, each hole was filled in after data was collected. Discussion The goal of this research is to enter into discussion the three areas respecting the sandy beach ecosystem. These include patterns of Zonation, density and species diversity and the association of sandy beach invertebrate in ungroomed and groomed sand beaches. Pattern of Zonation Dahl (1952) identified three different zones attributed to the "amount of tidal inundation: 1) subterrestial fringe (Talitrid-Ocypodid belt); midlittoral zone (Cirolanid isopods); and the sub-littoral fringe (rich and varied fauna)" (Monterey Bay National Marine Sanctuary: Sandy Beaches, 2006). It has been found that an additional zone should be added for beaches in central California, called "swash zone" (MBNMS, 2006) and the following figure is relative to the fauna zone as outlined by Dahl: Figure 1. Faunal zonation on the Moss Landing beach. From Oakden and Nybakken 1977. source: http://www.montereybay.noaa.gov/sitechar/images/beachf3.gif Many of the meiofauna species which inhabit the interstitial spaces between the sand grains are impacted by the actual sand grain size and depending on the tidal fluctuations that are present to either remove large or small parts of the tidal silt. This impacts the collectivity of the interstitial fauna. Many people who don't understand the communities which are present within both the silt layers and the content of the sand for feeding and breeding purposes need to understand that beach grooming has a large ecological impact on the macrofauna culture. Measure the association of sandy beach invertebrates and kelp wrack A study completed by the National Park Service, Channel Islands National Park measured the invertebrates found within the kelp wrack in 1999 in samplings found at nine different sites characteristic of "core transects to measure infauna, point-contact transect to measure macrophyte wrack" in an effort to gauge the level of these communities. The following were the results of their findings: Sand Crab (Emerita analoga) densities from transect ranged from 1456 per meter of beach at Water Canyon to 10,664 per meter of beach at Sandy Point (Table 1). Excirolana chiltoni found at all seven beaches ranged in density from 57/m of beach too nearly 4707/m of beach. Blood worms, Euzonus mucronata, were present at four of the seven beaches at relatively low density, less than 100/m beach except at Becher's Pier (938/m). Polychaetes, Nephtys californiensis, were present at Becher's Pier and Bee Rock. E. analoga megalopa were notably absent at all beaches. Ovigerous crab densities ranged from 2.51% to 58.97% of the population. The highest percentage of ovigerous crabs was found at Bee Rock, 59.97%. (Table 2). (National Park Service) Site Code Emerita Excirolana Euzonus Nephtys BB 3168.92 1657.83 938.47 160.19 BR 1666.76 198.10 0.0 115.29 CC 7879.24 134.52 89.81 0.0 FP 7539.44 638.90 0.0 0.0 SP 10663.54 4706.75 71.34 0.0 SW 3007.58 488.20 0.0 0.0 WC 1455.65 56.76 67.83 0.0 Table 1. Washzone transect species abundance summary. Mean number per meter beach. The following information applies to the macrophyte wrack summary: Table 4. Macrophyte wrack summary, percent cover. Macrophyte Wrack It was found at the National Park's Soledad West and Sandy Point sites that the total wrack coverage was actually highest at Soledad West with numbers showing 35.33% and 24.33% respectively (Table 4). (National Park Service) Through the preserving of the wracks and allowing them to flourish, the organisms and specimens that flourish will continue to do so. Through the assurance of large wrack amounts on sandy beaches, the numbers of specimens widely increases where numbers in many years will either flourish or diminish. By encouraging a more rigorous community between the beach lovers and the beach dwellers, specifically macrofauna species, there can be a finer balance. Such things that could be looked at would be ensuring certain parts of the beach are inaccessible to the public and make them "breeding areas" for the organisms so that they may have the kelp wracks to further develop. Such measures are taken for turtle sanctuaries and, if proven to the beach communities, that the need to preserve these macrofauna sites for the species will help to encourage stimulation. Density and Species Diversity in Groomed and Ungroomed Sandy Beaches By looking at Zuma beach for evidence of the density and the species as proportionate to groomed and ungroomed sandy beaches, the following was documented (see Appendix): that the majority of the macrofauna present was a large community of hopper and worm & poly organisms in ungroomed sandy beaches, but in both cases of ungroomed and groomed, there were low levels of crab organisms found. It is noteworthy that in analysis of the figures, ungroomed sandy beaches are an extremely desirable configuration for those organisms that are indeed thriving. What this t-test is telling is that because the P-value for hoppers is less than 0.05 there is a significant difference in hopper density between groomed and not-groomed beaches. Looks like there are probably more on the ungroomed beach. This may be due to the abundance of wrack food and shelter configurations to allow for the proliferation. Now just as interestingly, there is no difference between the ungroomed and groomed beaches as far as polychaete and sand crab abundance goes because both their p-values are greater than 0.05. It is only speculation as to why there is no difference for the polychaete and sand crab, but for the hopper as they may be able to survive in denser populations or they have a natural instinct for survival in less than hospitable surrounding. The two species of Megalorchestia (beach hopper), M. corniculata ("short-horned") and M. californiana ("long-horned) are commonly found high on the shore and another four less common species are also found on beaches in California. As beach hoppers respire in damp air and cannot tolerate prolonged submersion this may add to their ability to survive since they can survive and feed when the wracks are still left on the beaches for coverage since they burrow into the sand during the daylight hours. Since they scavenge in the open during nighttime low tides on all sorts of detritus of plant and animal origin the grooming of beaches does not effectually matter to their survival. Organisms Shelter and Food in Ungroomed and Groomed Sandy Beaches Organisms thrive where there habitats aren't threatened and they have the ability to eat of naturally occurring macrofauna such as kelp wracks. A dominant species found in the 'high zone' is the talitrid amphipods must rely on the ocean for survival and are commonly referred to as "beach hoppers" or "sand fleas". Talitrids "are generally nocturnal and leave their shelter at night and migrate down the beach searching for food" (Monterey Bay, 2006) It is extremely important for these species to have ample shelter in order to escape their natural preditors. In the 'mid-zone', the dominant species is the excirolana which is a "carnivorous scavenger and burrow into the top 1 cm of sediment at low tid, and leaves the sand to swim rapidly about looking for food when inundated" (Monterey Bay, 2006). In the 'swash zone', the dominant species is the sand crab, or emerita analoga, and are highly active, moving and reburying themselves frequently to maintain their location on the beach." (Monterey Bay, 2006) In the 'low intertidal zone' the dominant species is the "pismo clam, tivela stultorum, inhabiting shallow burrows with their hinge facing seaward." (Monterey Bay, 2006). By removing and grooming the natural habitats of these species, there is little left for their seeking shelter from natural preditors or seeking out food sustenance during their nocturnal adventures. Results Data Collection from Zuma Beach MEANS hopper blood+polychaete sand crab Ungroomed 1.529412 1.823529412 0.117647 1.7 0.1 0 0.61538 1.461538462 0.65385 1.1 0.5 0 0.76471 0.823529412 0.17647 1.5 0.65 0.1 1.52941 1.117647059 0.17647 groomed 0.10526 0.789473684 0.10526 0.1 0.15 0.2 0.15 0.4 0.05 0 0.4 0 0.11765 1.941176471 0 0.1 0.55 0.15 0.05 0.6 0.1 T-test for difference between ungroomed and groomed hopper blood+poly sand crab P 0.00044 0.43699 0.39378 Literature Cited Dugan, Jenifer E., Hubbard, David M., Martin, Daniel L., Engle, Jack M., Richards, Dan M., Davis, Gary E., Lafferty, Kevin D., Ambrose, Richard F. 1998. Macrofauna Communites of Exposed Sandy Beaches on the Southern California Mainland and Channel Islands. http://www.werc.usgs.gov/chis/DuganetalMMS00.pdf Jones, Alan, Gladstone, William and Hacking, Nicole. 2003. Sandy-Beach Ecosystems and Climate Change: Potential Ecological Consequences and Management Implications. http://www.nccnsw.org.au/climatechange/index.phpoption=com_docman&task=doc_download&gid=35 Monterey Bay National Marine Sanctuary. 2006. Overview of Beach Meiofauna and Macrofauna. http://www.montereybay.noaa.gov/sitechar/sandy2.html Richards, D.V. 1996 Sand Beach and Coastal Lagoon monitoring, Santa Rosa Island, 1994 Annual Report. Technical Report CHIS-95-06, Channel Islands National Park, Ventura, CA. http://www.nature.nps.gov/im/units/chis/HTMLpages/AnnlReports/99BLANNL.doc Richards, D.V., and D. Lerma 1996 Sand Beach and Coastal Lagoon monitoring, Santa Rosa Island, 1995 Annual Report. Technical Report CHIS-96-05. Channel Islands National Park, Ventura, CA. http://www.nature.nps.gov/im/units/chis/HTMLpages/AnnlReports/99BLANNL.doc Read More