Comparison of Aquatic Macroinvertebrates
in Pool and Riffle Habitats of
Michael Railling
Department of Biology
Undergraduate Student
Abstract
Aquatic
communities were quantitatively sampled with artificial substrate samplers in
pool and riffle habitats of
Keywords
Taxa, Richness, EPT’s, Chironomidae, Macroinvertebrate, Dissolved Oxygen, Pool, Riffle, Hester-Dendy Artificial Samplers.
Introduction
The
Blackburn Fork is a productive 4th order stream in Jackson and
Putnam counties (Baker 1994). On
Macroinvertebrates are good indicators of stream quality because they are closely associated with the conditions of the environment, they are easy to collect, they are relatively stationary, and they have a wide distribution (Early et al. 2002). Macroinvertebrate assemblages not only vary regionally they can also vary greatly at local levels (Heino et al. 2003). Abundance of the macroinvertebrates can be affected by many factors but habitat is the prime factor (Waters and Giovanni 2002). Invertebrates have adaptations to certain substrates. Some may prefer the larger cobble and faster currents of a riffle and other may prefer the slower and bedrock substrate found in a pool (Cushing and Allan 2001). Riffles generally have higher dissolved oxygen levels and a neutral pH. Water qualities including pH and dissolved oxygen can have a significant effect on the biota of a stream (Boto and Bunt 1981).
Pools and riffles are comparably different in water quality, but do they contain the same macroinvertebrate. Are the taxa and quantities different in pools and riffles. In my research I plan to prove that different taxa and quantities are found in these two habitats.
Methods and Materials
Six
different sites were selected in the
Four samplers were scrubbed, the two remaining riffle sample and two randomly selected from the pools. Invertebrates were separated from the substrate and identified to Genus. Chironomidae were left at family because identification is very time consuming (Wymer and Cook 2003).
Results
The pool samples had 655 organism from 11 different taxa, including Chironomidae. The riffles had 450 invertebrates from 17 taxa, including Chironomidae. Percent EPT and percent Chironomidae were similar in pool and riffle habitats. The pool samples were composed of 3.97% EPT and the riffles had 95.73% Chironomidae and the riffle had 3.78% EPT and 92.55% Chironomidae. However, the significant difference is other taxa. The pool habitat had 0.03% other taxa compared to the riffle with 3.78% other taxa.
Table 1.
Taxa Comparison of Pools and Riffles
of
Pool |
|
|
|
Riffle |
|
|
Genus |
|
Score |
|
Genus |
|
Score |
Cheumatopsyche |
13 |
|
Cheumatopsyche |
1 |
||
Ceratopsyche morosa |
1 |
|
Lype diversa |
1 |
||
Isonychia |
|
1 |
|
Isonychia |
|
5 |
Stenonema femoratum |
6 |
|
Stenonema femoratum |
1 |
||
Stenonema terminatum |
2 |
|
Stenonema terminatum |
9 |
||
Ephemerellidae |
1 |
|
Psephenus herricki |
1 |
||
Tricorythodes |
1 |
|
Helichus basalis |
1 |
||
Baetis |
|
1 |
|
Macronychus glabratus |
2 |
|
Libertia |
|
1 |
|
Calopteryx |
2 |
|
Antocha |
|
1 |
|
Nigronia serricornis |
2 |
|
Chironomidae |
627 |
|
Antocha |
|
3 |
|
|
|
|
|
Simulium |
|
2 |
|
|
|
|
Gammarus |
1 |
|
|
|
|
|
Hemerodromia |
1 |
|
|
|
|
|
Ferressia rivularis |
1 |
|
|
|
|
|
Orconectes |
1 |
|
|
|
|
|
Chironomidae |
416 |
Total 655 Total 450
Table 2. |
Pool And Riffle Comparison of |
|
|||
|
Taxa Richnes |
EPT Score |
% EPT's |
% Chironomidae |
% Other |
Pools |
11 |
17 |
3.97 |
95.73 |
0.03 |
Riffles |
17 |
26 |
3.78 |
92.44 |
3.78 |
Figure 1.
% Composition of Pools Figure 2. % Composition of Riffles
in
Discussion
In all 17 taxa were found in riffles and 11 were found in pools (Table 1). Two of the taxa, Antocha and Nigronia serricornis were found in higher numbers in the riffle habitats. The presence of these genra is directly associated with higher dissolved oxygen concentrations (Weigel et al. 2003).
Seventeen
EPT’s were found in the riffle habitats for a total
of 3.78% (Table 2, Figure 2).
Surprisingly, the pool habitat had 26 EPT’s
for a total of 3.97% (Table 2, Figure 1).
I agree with
A
total of 416 Chironomids were found in riffles;
making up 92.44% of the total composition (Table 2, Figure 2). Table 2 and Figure 1 show that 627 Chironomids were found in the pool sites making up 95.73
percent of the total composition. The
family Chironomidae usually has a greater abundance in poorer water quality (
Comparably
the richness and percent EPT’s in both habitats is
considerably low when compaired to reference streams
in
In conclusion both habitats are composed of different assemblages of organisms even though sampling sites are within meters of each other. The pools contain more EPT’s and Chironomidae, while the riffles has more taxa richness. Regardless of how much they differ, both pools and riffles are equally important for the survival of habitat specific organisms of Blackburn Fork.
Literature Cited