Maliau stream team project
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The Comparison of Stream Community Structure in The Maliau River and The Kuamut River, Maliau Basin.
Rindita Zulfikar, Alexandra Torres, and Aywen Chak Wang Hoong
Contents |
Abstract
There are two large rivers, The Maliau River and The Kuamut River, present near our lodging at Maliau Basin. The compositions of the two rivers are different in many ways. We wanted to determine whether the differences in river composition contributed to differences in the composition of macroinvertebrates and riparian vegetation in the two rivers. Our hypothesis was that there would be no difference in the composition of macroinvertebrates and riparian vegetation between the two rivers. In order to study this, we sampled macroinvertebrates and accounted the presence of plant species in three sites at each river. We used R to analyze our data by making cluster dendograms, ANOSIM graphs, and plots. We found in the clusters that the macroinvertebrates from each river were clustered together but we didn’t find this correlation with the riparian plants. From the ANOSIM graphs, we found that for both the macroinvertebrates and the riparian plants, the inter-specific variation between the two rivers much greater than the intra-specific variation within each river. From the plots, we found that for both the macroinvertebrates and the riparian plants that there were more species present in The Maliau River than in The Kuamut River. These analyses all indicated that our hypothesis was wrong but they were all consistent in describing the differences in the species composition of macroinvertebrates and riparian vegetation between the two rivers.
Introduction
Maliau Basin Water Catchment Area
Maliau Basin is unique in that it contains a water catchment area that is heavily composed of tannins. This presence of tannins in the rivers of Maliau is subsequently related to the increase of acidity of its rivers. The Basin is drained by only one river, the Maliau River, which flows through a canyon and joins the Kuamut River.[1] The acidity of each river is thought to influence elements of the biotic community that live inside and around the river. The elements we are concerned with are the plants and macroinvertebrates.
The tannins that are present in the rivers in Maliau Basin are the result of the leaching out of tannins from decayed vegetation. This process results in semi-transparent, acidic water that can be darkly stained and that can resemble tea or coffee.[2] Because of this characteristic, the species composition of plants and macroinvertebrates that live in rivers that contain many tannins might be different from the species composition of aquatic plants and macroinvertebrates found in different river communities.
Macroinvertebrates
Many people that are involved with biological monitoring efforts are interested in working with macroinvertebrates. This interest is likely due to macroinvertebrates being a very diverse group of long-lived species that react auspiciously and often predictably to human influences on aquatic ecosystems. However, these macroinvertebrates can vary from each other in terms of their specific requirements (i.e. food, freshwater, salinity) and environmental tolerances (i.e. acid stress, heavy metals, organic effluents), both of which directly affect their metabolism, abundance, and their presence or absence in an environment.
Ephemeroptera, Plecoptera and Trichoptera are three families of macroinvertebrates that are sensitive to most types of pollution. Because of this sensitivity, the number of individuals in these orders will decrease significantly with a decrease in water quality. On the other hand, Tubificidae c.f. Branchiura are not as sensitive to pollution, hence, the number of these individuals may increase in response to organic pollution. Because of this spectrum of sensitivity to pollution, the health status of a stream can be determined through an assessment of population abundance and community structure of macroinvertebrates.
Riparian Vegetation
Riparian vegetation maintains and stabilizes aquatic ecosystems by providing bank stability, which in turn contributes to a decrease in erosion of that area, by filtering sediment, by processing nutrients (particularly nitrogen) from the catchment, and by providing shade which contributes to the moderation of water temperature. Aquatic macroinvertebrates are adapted to specific chemical and physical conditions in water communities. Therefore the species composition of a macroinvertebrate community in a waterbody can be used as an indicator of the health of that waterbody.
Questions
- Bearing in mind that The Maliau River and The Kuamut River each have entirely different water chemistries; are there any differences in stream community structure between The Maliau River and The Kuamut River?
Methods
Field Methods
For the macroinvertebrate community assessment, dip nets and kick sampling methods were used to collect both the surface and benthic macroinvertebrate fauna. These collected living specimens were kept alive in plastic vials and were brought back to the laboratory for identification at the family level. Quantitative data was also recorded.
We wanted to sample the riparian plants on the banks of the Maliau River and the Kuamut River. To accomplish this, we chose three sites at each river, each site being a 30 meter by 5 meter transect along the bank of the river. At each site, we took note of the presence of riparian plants by recording what species were present and recording the number of individuals of each species that grew within the site. In addition to recording the plants, we recorded some of the physical parameters of each site such as pH value, water velocity, color of the water, and the substrate.
Hypotheses
Cluster Dendrograms and Analyses of Similarities (ANOSIM) generated using 'R' statistical software were used to test the hypotheses postulated as follows:
- Null Hypothesis
There is no difference in stream community structure between the Maliau River and the Kuamut River.
- Statistical Hypothesis
There are differences in stream community structure between the Maliau River and the Kuamut River.
Results
Macroinvertebrate Community Structure
Figure 1a is a cluster dendogram of the mactoinvertebrate community in both rivers. In this graph, there are two main clusters which significantly represent the two main rivers; Site 1, Site 2, and Site 3 represent the Maliau River while Site 4, Site 5, and Site 6 represent the Kuamut River. Figure 1b is an ANOSIM plot for macroinvertebrates in the two rovers. This plot significantly indicates that there is larger inter-specific variation between the two rivers than intra-specific variation within each of the two rivers; the p-value of this plot is 0.101. Comparing intra-specific variation within each river, The Maliau River has a higher similarity index than The Kuamut River. Additionally, there are also higher numbers of macro-invertebrate families found in The Maliau River; see figure 1c.
Riparian Vegetation Community Structure
From the cluster dendrogram, figure 2a, one can see that there are two main branches of sites that describe the riparian plant community. The plant community in site 4 and 5, both sites being from The Kuamut River, are clustered in one branch, and the rest of the sites are clustered in another branch. Site 3, from The Maliau River, and site 6 , from The Kuamut River, both appear as a similar community. Similarly, site 1 and site 2, both sites being from The Maliau River, also appear as a similar community and appear to be related to each other by falling in the same branch. The ANOSIM plot for the plants, figure 2b, also shows larger inter-specific variation between The Maliau River and The Kuamut River compared to intra-specific variation within each river. The p-value of this plot is 0.095. Riparian plants at The Kuamut River have a higher similarity index than plants at The Maliau river. There are also a higher number of plant species found in The Maliau River rather than in The Kuamut River, see figure 2c.
Discussion
Macroinvertebrate Community Structure
Assuming that the sampling effort was constant throughout the project, we can clearly see that there is significant variation in the stream macroinvertebrate community structure observed between The Maliau River and The Kuamut River. In other words, the null hypothesis of there being no difference in stream community structure between the two main rivers is rejected. This rejection is evidently indicated by the two main clusters found in the cluster dendogram, each cluster corresponding to one river.
ANOSIM statistics for macroinvertebrates indicate that inter-specific variation of macroinvertebrates between the two rivers is significantly larger than intra-specific variation within each river. These statistics further demonstrate that the rivers indeed had different macroinvertebrate community assemblages and that their community structures could be largely driven by the differences in water chemistry. The differences in water chemistry can be attributed to the differences in pH value of each river. The Maliau River has a consistent pH value of 5 and The Kuamut River has a consistent pH value of 5.5. Despite the higher acidity of The Maliau River, a larger number of families were observed at The Maliau River than at The Kuamut River. This discrepancy may be due to the difference in the water velocity at each river. The mean water velocity for The Maliau River is lower, 0.35m/s, than the mean velocity for The Kuamut River, 0.49m/s. The fact that the water current speed is greatest for The Kuamut River could indicate that the water current imposes a mechanical stress factor to most aquatic macroinvertebrate fauna. This stress factor would cause the fauna to maintain a static position. Certain families of macroinvertebrates, such as the Gerridae and Veliidae, have evolved specialized traits which enable them to cope with fast-flowing waters. These two families are both specialists in that they are both adapted to fast flowing water by having peculiar paddle-like legs that allow them to float on water[3].
Other factors which control the community patterns are (i) micro-temperature which affects the physiology and behavior of the organisms, (ii) the substratum (i.e. a loose or stable type of substratum) which affects the preference of aquatic faunas, (iii) the oxygen content (iv) susceptibility to drought which enables certain organisms to survive if the water level falls and exposes the organisms to the air, and (vi) the availability of food [4]. Additionally, a larger sampling effort would be recommended if time was not limiting.
Riparian Vegetation Community Structure
A cluster dendrogram of the plants shows two different clusters of riparian vegetations. The left cluster describes the similarity of riparian plant composition between two sites of The Kuamut river, site 4 and site 5, and the right cluster indicates that the composition of plant morpho-species in the rest of the sites are very similar to each other. Site 4 and 5, both from The Kuamut River, are dominated by the same morpho-species of grass. A Melastoma species and a Monocotyledonae aquatic plant are both abundantly present at site 1 and 2, both sites of which are in Maliau River, but they are not as abundant in any of the other four sites. This abundance indicates that there is a slightly different community composition between the two clusters.
The results of ANOSIM statistics for plant communities, figure 2b, are similar to the results of ANOSIM statistics for macroinvertebrate communities. The ANOSIM statistics for plants show that inter-specific variation of riparian plants between The Maliau River and The Kuamut River is significantly larger than intra-specific variation within each river. This is supported by the fact that The Maliau River and The Kuamut River have different riparian plant communities. Other factors that can influence these results are water pH value, which depends on the tannin concentration in the water, and bottom substrate. When the plant data for the two rivers are plotted, figure 2c, the results indicate that The Maliau River has a higher diversity of riparian plants than The Kuamut river. This suggests that the tannin presence in the water is not the main factor that affects the riparian plant community. The smaller number of plant morpho-species that are found in The Kuamut river banks could be due to the poor condition of the river banks from logging activity. Because of the smaller number of plant morpho-species, The Kuamut River has a slightly higher similarity index than The Maliau River.
Because riparian vegetation plays a role in increasing biodiversity and serves to provide habitat for native fauna, continuous research and monitoring of riparian vegetation (i.e. wide mapping) should be maintained. The loss of riparian vegetation through clearing, livestock grazing or recreational uses, can contribute to the loss of these benefits and the decrease of the overall condition of the stream (www.wsroc.com.au.).
Physical data parameters such as velocity, riparian zone width, and sediment deposition, are very important in studying riparian and aquatic ecosystems, thus the proper equipment is needed to more accurately measure these parameters. example, (http://www.co.mifflin.pa.us).
References
- ↑ http://www.ysnet.org.my/maliau/
- ↑ http://www.wikipedia.org/
- ↑ Allan, J.D. 1995.Stream Ecology – Structure & Function Of Running Waters. Chapman & Hall
- ↑ Hynes, H.B.N. 1970. The Ecology Of Running Waters. Liverpool University Press.
http://www.co.mifflin.pa.us/kishwatershed/lib/kishwatershed/sample_data/phys/physical_data.htm
http://www.wsroc.com.au/wqm/ae_riparian_vegetation_monitoring.html http://en.wikipedia.org/wiki/Riparian_zone
www.dse.vic.gov.au
