Comparison of Correlations Between Environmental Characteristics and Stream Diatom

FA_2015_BIO_230 Journal of What Was, What Is, and What May Be Vol 23 (7):1-10






Environmental Biology


Comparison of correlations between environmental characteristics and stream diatom

assemblages characterized at genus and species levels.

Division of Science & Environmental Policy, California State University Monterey Bay, Seaside,



The document presents an attempt to methods of measuring the degree of correlation between

variables in an ecosystem. The methods used here depend on the combination of knowledge of

the level of correlation between diatoms and the other variables within the system that has a

causal relation. The introductory part gives an overview of the background study of diatom

existence in the United States and hypotheses guiding this study. Data collection methods

included sampling, interviews, and questionnaires that guided the study to obtain results

analyzed and represented in numeric tables and graphs. The results are summed up in a

conclusion that gives remarks about the findings of the study.

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In biological and environmental sciences, one often has to encounter with various

characteristics or situations with a significant correlation because of a complex of interesting

uncontrollable and obscure causes. The degree of correlation between variables can be measured

by well-known methods. Diatoms are photosynthesizing materials, that contains a siliceous

skeleton (frustule) and exist in every aquatic habitat including the entire marine environment, in

fact almost anywhere moist. Biological surveys of stream communities have long been used to

assess the impacts of human activities on receiving waters (Whitton and Kelly 1995, Lowe and

Pan 1996, Stoermer and Smol 1999, Stevenson and Smol 2001). This survey of biological

assessment programs was carried in the United States and reported that thirty-nine States relied

on biological information in stream assessments, but only 27 states used this information in

setting water-quality criteria (Davis et al. 1996, Kroeger et al. 1999).

H1: there are more diatoms in the deep oceans of United States (x) than in the shallow oceanic

areas of United States(y)


YH0: There will be no difference in the size of populations of diatoms between the deep (X) and

shallow (Y) areas.>

X = Y


Data used in analyses were compiled from the United States Environmental Protection

Agency’s Environmental Monitoring and Assessment Program (EMAP) surveys of

MidAppalachian streams conducted from 1993 to 1995 (Hill et al. 2000). Species were collected

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from forty-five rivers in 1993, 46 in 1994, and 108 in 1995. More than 10% of the rivers were

selected for the sampling process near the beginning and the end of the sampling period to

examine the diatom metric stability. However, data were gathered from nine hundred and ninety-

nine during 233 site study. The traits from each stream site included nineteen streams chemistry

variables, 13 stream habitat variables, and 15 land-use variables. Diatoms were collected from

erosional habitats at each of nine transects along the river reach, made into a single sample for all

the rivers, and brought back to the laboratory for processing (Hill et al. 2000). Environmental

preferences of the diatom species were taken from published research (Lowe 1974, van Dam et

al. 1994).

Research methodology

The project will be executed through the collection and collation of information and data

from the following sources and methods;

• Literature Reviews: This entails visiting libraries and consulting relevant literature on the

project design.

• Case Studies: This required a physical or virtual visit to existing xeriscapes to ascertain

what is required, what is provided for, and what is lacking.

• Interviews: This involved asking investigative questions of persons who are

knowledgeable and well versed with xeriscape landscapes.

• Internet sources: This means getting data from the world-wide web or network of


The research methods employed included data collection, data processing, data analysis

and methods to evaluate the accuracy of the results obtain to minimize the occurrence of

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errors. The research method involved observation checklists, utilization of secondary data,

sampling, administration of structured interviews and questionnaires and photographs.

Figure 1photo of people performing transects


The sampling process involved forty-four genera and 522 species of diatoms from the study

streams (Table 1). Fifteen genera were represented by a single species; another ten genera had,

five species. Ten genera had .10 species, with Navicula (119 species), Nitzschia (66),

Table 1 Diatom genera, number of species (including varieties), and environmental preferences (based on average scores for
species within a genus) for Mid-Appalachian streams.

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Achnanthes (48), and Eunotia (44) being the most species-rich (Table 1). Canonical correlation

analyses of the genus- and species-level attributes and the environmental variables resulted in

significant canonical axes. A description of a nutrient-enrichment/stream-size gradient entails the

2nd canonical axis (W2), which was positively correlated with nutrients (total P and total N), Cl-,

total suspended solids, fine-grained stream sediments, and agricultural land utilization, and

negatively correlated with river width and depth (Table 2). Generic richness in any specific river

ranged from 3 to 17, with a mean of 11 genera per stream, whereas species richness ranged from

10 to 72 with an average of 34 species per stream. Genera richness was significantly correlated

with species richness. Acidobiontic diatoms presented zero percent to ninety-nine percent of both

the genus- and species-level counts, and both genus- and species-level traits were similarly

correlated with the selected environmental variables (Table 3). Both genus- and species-level

traits were significantly correlated with W1, the human disturbance/geomorphology gradient.

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The relative abundance of eutraphentic taxa revolved between zero percent to fifty-six percent of

the genus-level counts and from zero percent to ninety percent of the species-level counts, and

genus-level counts were significantly correlated with the species-level count.


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Figure 2: Comparisons of diatom taxa abundance (A), , and acidobiontic (C), motile (b), and pollution-
tolerance (c) attributes based on genus and species counts in streams in the MidAppalachian region of the
United States.




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A simple measure of the reliability of genus level attributes as an alternative to species-

level attributes is the correlation between attributes based on diatom counts at the two taxonomic

levels. Perfect correlations (r 5 1.00) would suggest that there is no loss of information, for the

measures presented, by limiting identifications to the generic level. Genus- and species-based

attributes were significantly correlated, suggesting that for a reason diatom identification only to

genus may adequately characterize the diatom assemblage’s response to environmental

conditions. For those diatom assemblage attributes in which genus-level counts are highly

correlated with species-level counts (acidobiontic and motile attributes), it appears that genus-

level counts may suffice. Deviations from perfect correlations have simple explanations, and

their impacts on our assessments may be small. For example, the close agreement between

genus- and species-level counts of acidobiontic diatoms reflects the fact that most acidobiontic

species are in genera that are also classed as acidobiontic (Eunotia, Frustulia, Pinnularia,

Tabellaria). Exceptions to this fact include acidobiontic species in genera not classified as

acidobiontic: Achnanthes (1 sp.), Anomoeoneis (2), Aulocoseira (2), Cymbella (2), Fragilaria

(1), Navicula (5), Neidium (1), Stenopterobia (1), and Surirella (1). The impact of excluding the

above species from the genus-level assessment of acidobiontic diatoms can be determined only

by species-level counts, but the near-perfect correlation of the genus- and species-level attributes

suggests that this discrepancy is small.


Conclusions our results support four general conclusions. First, richness attributes are not

consistently or predictably related to gradients of human disturbances within a catchment and

should be used cautiously for environmental monitoring. Second, diatom assemblage attributes

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based on genus or species sensitivities and tolerances to environmental conditions, even based on

European Diatom autecology, are consistently and reliably related to gradients of human

disturbances within a catchment. Third, genus-level diatom assemblage attributes for some

environ 308 Volume 20 B. H. HILL ET AL mental gradients are predictable and appear to be

relatively precise compared to species-level attributes. Fourth, the environmental gradients with

which genus-level diatom assemblage attributes are most strongly correlated are those gradients

that involve morphological (motility) or physiological (pH tolerance) adaptations that are related

to evolved genus-level characteristics.


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Charles, D. F. 1985. Relationship between surface sediment diatom assemblages and lake water

characteristics in Adirondack lakes.

Ecology 66: 994–1011. Chessman, B., I. Growns, J. Curry, AND N. Plunkett-Cole. 1999.

Predicting diatom communitiesat the genus level for the rapid biological assessment of


Freshwater Biology 41:317–331. Crossey, M. J.,and T. W. LA Point. 1988. A comparison of

periphyton structural and functional responses to heavy metals. Hydrobiologia 162:109–


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