• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Observe the effects of herbivores on the abundance of algae and to test whether the presence of algae on the substratum determines further settlement of more algae.

Extracts from this document...

Introduction

Abstract An experiment was carried out on the rocky intertidal shore at Maroubra beach in NSW. The aims were to observe the effects of herbivores on the abundance of algae and to test whether the presence of algae on the substratum determines further settlement of more algae. The experiment was carried out by dividing 20 plots into 5 treatments, incorporating a control, looking at the effects oh herbivore exclusion through anti-fouling paint and algal settlement through scraping of the rocky shore. It was shown that the removal of herbivores significantly altered the abundance of algae but that scraping had no significant effect for algal recruitment. Reasons for this are discussed. Introduction. The 'Sub tidal zone that connects land and sea has been somewhat frivolously studied by ecologists yet comprehensively studied by both zoologists and marine botanists' (adapted from; Carefoot, T., 1977), the ecological complexity is of great magnitude and there is an acute relationship between the organisms of the intertidal zone. Intertidal organisms have become specially adapted to survive the rapid and significant changes in temperature, salinity, moisture, pH, dissolved oxygen, and food supply that occur on a daily basis due to the movement of the tides. This distribution pattern of different species along the shore is referred to as vertical, or intertidal, zonation. Typically, physical stresses (abiotic) set upper boundaries and biological stresses (competition, predation etc.(biotic)) ...read more.

Middle

so as to enable the increase of green algae colonising the rocky shore. Results for: Bare rock (significant) Two-way ANOVA: week6 versus Herbivores, Scraping Source DF SS MS F P Herbivores 1 12769 12769.0 55.16 0.000 (significant) Scraping 1 100 100.0 0.43 0.523 Interaction 1 81 81.0 0.35 0.565 Error 12 2778 231.5 Total 15 15728 Results for: Limpets (significant) Two-way ANOVA: week6 versus Herbivores, Scraping Source DF SS MS F P Herbivores 1 1425.06 1425.06 70.74 0.000 (significant) Scraping 1 1.56 1.56 0.08 0.785 Interaction 1 14.06 14.06 0.70 0.420 Error 12 241.75 20.15 Total 15 1682.44 S = 4.488 R-Sq = 85.63% R-Sq (adj) = 82.04% There is a significant difference in the occurrence of limpets between herbivore treatments but no significant difference between scraping treatments. There is no significant interaction between the two. The graph indicates that the copper based paint treatment worked effectively to exclude limpets from the herbivore absent (HA) quadrats as opposed to quadrats that were not painted, herbivore present (HP). There is no significant difference in the abundance of encrusting algae between herbivore treatments and no significant difference between scraping treatments. There is no significant interaction between the two. Furthermore; There is no significant difference in the abundance of gastropods between herbivore treatments and no significant difference between scraping treatments. There is no significant interaction between the two. Discussion; The hypothesis that herbivores limit the abundance of algae on mid-levels on a rocky shore has been proven to be correct (Underwood and Jernakoff, 1981). ...read more.

Conclusion

If not than our results are not representative. Was the wave action and weather conditions representative? Physical factor also play a large role in the presence of any intertidal organisms (Creese, 1988). The surfing lull over the winter 04' has been described by some as 'uncanny' it is the wave action that acts as transport for new algal 'colonists' thus, if there is no waves there is no colonists. This effects recruitment of algae. Seasonal effect and proportion of algae growth. This experiment may in fact have been conducted at a time that is non representative of the community's natural state for reasons in species life cycles and seasonal proportion (adapted from; Williams,G.A.et al ). Human error can also be mentioned as a possible reason to the lack of statistical significance in the results, eg; was scraped areas scraped correctly? Were data figures counted correctly? Were species identified correctly? Was randomly selected areas random? Maybe herbivory is not from Gastropods? We have not included the herbivory from crabs this is a somewhat substantial proportion I would have thought, thus we may be attributing consumption to the wrong species. The results of this experiment show that herbivorous grazing limpets have a significant effect on the growth of green algae on a rocky shore in the mid-high region. Limpets dominate over other forms of gastropods due to their more prostrate morphology, resisting wave action and desiccation. Removing algae from the stratum prior to sampling showed very little effect on algal growth, and the paint used to mark out plot boundaries showed none. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Zoology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related University Degree Zoology essays

  1. Free essay

    A review of a case study on feline aggression and possible treatments

    'This particular kind of aggression is not unexpected when one considers that free ranging male cats commonly defend their territories, and in particular, defend a potentially scare resource...' (Levine, Perry, Scarlet and Houpt, 2004). In wild feline social systems a few males mate with the rest of the females, resulting in a skewed sex ratio.

  2. Animal Testing

    (Why Conduct Literature Searches for Alternatives?) Most of the large manufacturers of personal care and household products could implement strategies that are considered cost effective, better predictors of human injury, produce far quicker results, and do not associated with animal cruelty. (Animal Testing Alternatives) Government and humanitarian agencies have financed researches into the substitutive strategies since the 1960s.

  1. The positive correlation shows that the older the molehill the higher the species diversity ...

    The species frequency was then calculated by giving each species present in the quadrat a number from 1 to 16, according to how many 5 x 5 cm squares they were present in. The species were identified using a species list that was compiled previously.

  2. Investigating the effect that group size has on the vigilant behaviour of flocks of ...

    Data collection was also stopped if there was an obvious disturbance among the birds (e.g. if a dog was near them). When data collection was complete the means for each of the type of behaviour for each group was calculated.

  1. This report was commissioned by Sunderland City Council to assess the ecological and educational ...

    In addition there is evidence of some historic limestone quarrying activity which has produced areas of exposed limestone. To the south of Rock Farm lies a large area of Ash dominated woodland, fringed by dense Hawthorn scrub. 4. Habitat types - 4.1 Improved Grassland This habitat has been sown and maintained by mowing to be used as amenity grassland.

  2. The grasslands of North American are called as prairies; they cover about 1.4 million ...

    Thus, the Great Plains are divided into short, mid and tall grass prairies based on the height of the grasses and the nature of individual plants rather than the presence of individual species or genera of grasses. Fire is an essential factor of the grassland biome.

  1. This paper attempts to investigate whether the associated consequences of global warming could lead ...

    These features are also displayed by Skates and Rays a member of the class Chondrichtyes but of the Super-Class 'Batoidea' with the main difference being the gill slits are on the bottom of the flat body. There are 354 species listed by the FAO (Food and Agriculture Organisation USA).

  2. What is a species? How do new species arise? What is the difference between ...

    The BSC has problems when dealing with plants, or asexual populations. A number of land plants undergo interspecific hybridisation between clearly different species, and the definition also has limited application to land plants that primarily self-pollinate. It is also not always possible to know whether two groups of organisms can

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work