Invertebrate Diversity

1450 Words 6 Pages
This study examined the effects of physical factors on diversity in freshwater environments by observing invertebrate diversity in riffles and pools in a freshwater stream. It was hypothesized that differences in invertebrate diversity between riffles and pools would be due to physical factors in the environment. To test this hypothesis, invertebrates were collected from each environment and classified by their taxa, and Shannon-Simpson indices were produced from these data to analyze the differences in diversity between the two environments. It was found that pools have a significantly greater species abundance, while riffles have a significantly greater species evenness. These results can be used to further examine changing abiotic factors, …show more content…
J. Jennings et al (1992). Specifically, in freshwater habitats, abiotic factors such as temperature and dissolved oxygen levels largely determine the size and diversity of the community the habitat is able to support (L. R. Bodensteiner et al., 2011).
In this present study, two freshwater stream environments were studied: riffles, which are rocky areas with fast-flowing, shallow water, and pools, which are areas of deeper, slow-moving water. The effects of biotic factors on species diversity have already been studied. Competition between freshwater, inhabiting organisms generally results in a decreased population size for both organisms and a displacement or elimination of one of the competing species (D. M. Baltz et al. 2011). This present study observes the effects of physical abiotic characteristics on organisms living in a freshwater ecosystem.
For this study, it was hypothesized that the types of invertebrates that inhabit each environment will differ due to physical differences between the riffles and pools. If this hypothesis is correct, it is predicted that riffles will have a higher species diversity due to physical, abiotic differences, such as nutrients, oxygen, and water
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These findings supported the hypothesis that the types of invertebrates that inhabit riffles and pools will differ due to physical differences in the environments.
These findings were also supported by another study performed by P. Logan et al (1983). This study, performed in upland rivers in North America, did not investigate the effects of any biotic factors on populations in the two environments; rather, only the densities of the organisms in each environment were measured. This study found that riffles had a significantly greater mean density of invertebrates living in the benthic layer than pools did, which is consistent with the results of the present study.
A study performed by G. C. Hose et al (2004) also found that riffles had a greater species richness than pools. These differences in diversity were attributed to physical differences between the two environments, such greater temperature fluctuations and less dissolved oxygen in pools. Riffles provide an environment where the temperature is more stable and there is more dissolved oxygen, because riffles mix and agitate water more than pools do (G. C. Hose et al. 2004). Thus, riffles can better support a wide variety of

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