What do the results mean?
As most of the diversity calculations came out non-significant, it cannot be concluded that productivity has either a positive, or a negative effect on settlement of larvae as sampled at this small scale. However, there is still meaning in the outcome of this experiment: we just have to look a little harder to find it.
Whether or not the fertilizer had a true interaction with the plant and animal life in the intertidal zone, it seems most apparent, given the published studies confirming the positive relationship between biodiversity and productivity at large scales, that the scale I chose to conduct my research at was too small to expect results. One explanation for scale dependency in this relationship is that dissimilarity in species composition increases with productivity at larger scales (Chase and Leibold, 2002). If this study is to be continued, I would recommend that it be done at both spatial and temporal scales that are a step larger in extent, as well as provide a gradient of enrichment to determine the shape of the biodiversity-productivity relationship. Furthermore, I would recommend a fully thought out list of species that the researcher was confident in identifying. Because data points for my small-scale study were so few, mistakes, misjudgments, and poor grouping decisions held significantly more weight than they should have.
THE FERTILIZER HAD NO EFFECT
The most likely explanation for the results seems to be that the fertilizer had no effect. It is possible that the amount of nutrients in the enriched environment was not enough to cause a significant difference in habitat quality, or it also may be that the nutrients contained in the fertilizer were not a limiting factor in the rate of carbon fixation by primary producers, and therefore there was no increase in actual productivity even as the potential for it increased.
Conservation Implications
The primary of coastal and pelagic waters serves the key function in marine ecosystems of transferring energy from organic compounds into digestible components that sustain populations of all subsequent levels in the food web. Both phytoplankton and zooplankton are responsible for the persistence of the fish species we use or abuse as economic resources. As if over harvesting of marine ecosystems was not bad enough, humans continue to make environmentally unsound decisions that ultimately influence the surrounding systems. The use of fertilizers, chemical pesticides, poor drainage and sewage systems all contaminate oceans, lakes and streams so that these aquatic environments are no longer the same as they were when these organisms evolved.
Research deciphering the relationship between nutrients and ecological communities at multiple scales must continue if we are to have the proper awareness to prevent further ecological damage from further destroying our waters and the life they contain.
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THE FERTILIZER HAD AN EFFECT
An alternative explanation is that the fertilizer actually did have an effect, but for some reason the results could not detect it. Perhaps I was inconsistent in my methods of data collection, or perhaps my experimental design was flawed. As explained in the page called Life Lessons, I made many mistakes throughout this entire process, and my former impressions that such an experiment would not pose a challenge are but a very distant memory. Barring the fact that my data may be flawed, there might be ulterior processes that are negating the effects that the fertilizer is having. If top-down processes are more dominant in nutrient-rich areas, perhaps grazers and omnivores preferentially fed on the enriched habitats and threw the results. There was certainly a trend indicating that biodiversity was less in the enriched habitats, although the results were never quite significant.
Certainly, one interesting aspect to come out of this research was the significant difference in mite abundance that occurred between the two environments. The feeding strategy of the marine might may give some indication about the differences between the two environments, and may be an interesting subject to explore for future study.
For More information on micro-communities of marine larvae,
