Aquatic environments are being modified by anthropogenic activities regarding their biological, physical, and chemical conditions; even pristine aquatic ecosystems can be threatened. This study focused on the biological monitoring of Maroaga Stream—a first order stream located in an Environmental Protection Area in the Amazon using the Biological Monitoring Working Party (BMWP) Score System. The BMWP Score System revealed that the Maroaga Stream was a Class I stream (score of 138 points), indicating clean or not significantly altered water quality. The results suggest the adequate environmental conditions and ecological responses of the Maroaga Stream.
The last few decades have witnessed increasing concerns about environmental problems produced by the anthropogenic degradation and misapplication of natural resources. Policies regarding the correct usage of water are extremely important because the availability of clean freshwater resources is essential for the maintenance of life throughout the world [
Freshwater environments are subjected to increasing degradation. In addition to the extensive range of natural stresses encountered by organisms in their habitats, human activities can generate other environmental stresses [
In Brazil, concerns regarding the conservation of watersheds led to legislation that focused on the proper management of water resources [
Due to on-going threats to aquatic ecosystems in the Amazon, a better understanding of Amazonian biodiversity could lead to specific conservation studies of these ecosystems [
Freshwater environments can be monitored by physical, chemical, and biological parameters. Biological parameters integrate information over longer periods of time and better represent the responses of aquatic habitats [
Aquatic insects and other organisms in freshwater systems are also monitored to gauge subtle and profound effects that changes in water quality can have on aquatic life. Biomonitoring of this sort has some decided advantages when compared to other types of analysis, for example, chemical analysis. Benthic insects and other invertebrates maintain relatively fixed positions in the aquatic environment. Thus, the freshwater invertebrates can reflect both short and long term shifts in water quality. Chemical analysis and/or animals that have great mobility, such as fishes, tend to present snapshots of the period when samples were taken [
Some freshwater invertebrates are very sensitive to stresses produced by pollution, habitat modification, or severe natural events, while others are more tolerant [
There is a clear link between the health of the Amazon and the health of the planet. The Amazonian landscape contains one in ten known species on Earth, 560 million hectares of dense forests, and 4,100 winding rivers [
The goal of the present study was to assess the environmental health of Maroaga Stream, a first order watercourse, located in an Environmental Protection Area of Presidente Figueiredo, Amazon, Brazil, using aquatic macroinvertebrates as bioindicators.
The study area is located in Presidente Figueiredo, Amazon, Brazil (02°02′58, 7′′ S 59°58′22′′ W), north of Manaus (Figure
Study area (adapted from Amazonastur/Proecotur, 2004).
Development of the Maroaga Cave system (Figure
Maroaga Cave entrance ((a) left: internal view; (b) right: external view).
Maroaga Stream (Figure
Maroaga Stream ((a) left: internal view; (b) right: external view).
Macroinvertebrates constitute a heterogeneous assemblage of animal taxa, many of which are sedentary, and some have relatively long life spans. Many methods of data analysis, including pollution indices and diversity indices, have been devised for the group. The widespread, almost universal, use of these techniques testifies to their value in water quality management [
The index used here to assess the environmental quality of the Maroaga Stream based on macroinvertebrates was the BMWP Score System, created by Hellawell [
The BMWP Score System is an index requiring limited taxonomic precision, thus saving time and economic resources. Being simple and easy to apply, the BMWP Score System requires taxonomic identification of the invertebrates only to the family level but can accept order or even class for some groups. This index summarizes presence/absence and tolerance of the taxa present at a site. Several physical and chemical parameters that are correlated significantly with benthic community structure are used to predict unimpacted benthic community structure [
BMWP classes, scores, categories, and result interpretation (adapted from Armitage et al., 1983 [
Class | BWMP score | Category | Interpretation |
---|---|---|---|
I | >150 | Good | Very clean water |
101–150 | Clean or not significantly altered | ||
II | 61–100 | Acceptable | Clean but slightly impacted |
III | 36–60 | Questionable | Moderately impacted |
IV | 15–35 | Critical | Polluted or impacted |
V | <15 | Very critical | Heavily polluted |
BMWP taxa scores: class, order, or family (adapted from Alba-Tercedor, 1996 [
Taxa | Score |
---|---|
Ephemeroptera: Leptophlebiidae, Leptohyphidae |
10 |
|
|
Odonata: Coenagrionidae, Calopterygidae, Cordulegastridae, Gomphidae, and Libellulidae |
8 |
|
|
Plecoptera: Nemouridae |
7 |
|
|
Crustacea |
6 |
|
|
Coleoptera: Elmidae, Dryopidae |
5 |
|
|
Arachnida: Hydracarina |
4 |
|
|
Annelida: Hirudinea |
3 |
|
|
Diptera: Chironomidae, Culicidae, Ephydridae, Muscidae, and Thaumaleidae | 2 |
|
|
Annelida: Oligochaeta |
1 |
The overall BMWP score evaluation is the sum of all scores of each taxon (class, order, or family) present in a study site (Table
Initially, the BMWP table was based on invertebrates found in Iberian Peninsula watersheds. Therefore, adaptations were needed for proper use in the Amazon. These readjustments were based on the studies of Bobot et al. [
On March 29, 2008, the aquatic macroinvertebrates were collected at 12 sampling locations, the first point starting 100 m downstream of the entrance of the Maroaga Cave and proceeding downstream at 25 m intervals. All sampling stations were located where the stream was a first order stream.
Macroinvertebrates were collected for a period of 15 minutes by manual collection, that is, examining the substrate, fines, sand, gravel, cobbles, boulders, leaves, and submerged branches, from riffles and pools at each location. Samples were collected using kick nets and/or manually (kick samples). In riffles the kick net was held vertically on the stream bed and an area of the substratum was disturbed by hands; stream flow carried the sample into the net. In pools, the stream bed was disturbed vigorously by hand and the dislodged sample was pushed into the net. Each sample was placed into a white plastic tray with dimensions of
We collected 253 individuals. They belonged to 25 major taxonomic groups (Table
Aquatic macroinvertebrates present at each sampling location.
Invertebrates | Sampling locations | Points | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | ||
Blattaria: Blattidae | + | + | 1 | ||||||||||
Coleoptera: Curculionidae | + | 4 | |||||||||||
Coleoptera: Helodidae | + | 3 | |||||||||||
Crustacea | + | + | 6 | ||||||||||
Diptera: Chironomidae | + | 2 | |||||||||||
Ephemeroptera: Baetidae | + | 4 | |||||||||||
Hemiptera: Gerridae | + | 3 | |||||||||||
Hemiptera: Naucoridae | + | + | + | + | + | 3 | |||||||
Hemiptera: Veliidae | + | 3 | |||||||||||
Hydracarina: Aranae | + | 4 | |||||||||||
Lepidoptera | + | + | + | + | + | + | + | 1 | |||||
Megaloptera: Corydalidae | + | + | + | + | + | + | + | + | + | + | + | 4 | |
Odonata: Calopterygidae | + | 8 | |||||||||||
Odonata: Coenagrionidae | + | + | 8 | ||||||||||
Odonata: Cordulegastridae | + | 8 | |||||||||||
Odonata: Gomphidae | + | + | + | 8 | |||||||||
Planaria | + | + | + | + | + | + | 5 | ||||||
Plecoptera: Perlidae | + | + | + | + | + | + | + | + | + | + | + | 10 | |
Trichoptera: Calamoceratidae | + | + | + | + | + | + | 8 | ||||||
Trichoptera: Helicopsychidae | + | + | 5 | ||||||||||
Trichoptera: Hydropsychidae | + | + | + | + | + | + | + | + | + | + | 5 | ||
Trichoptera: Leptoceridae | + | 10 | |||||||||||
Trichoptera: Odontoceridae | + | + | 10 | ||||||||||
Trichoptera: Philopotamidae | + | + | + | + | + | + | 8 | ||||||
Trichoptera: Polycentropodidae | + | 7 | |||||||||||
|
|||||||||||||
Total | 138 |
Based on our results, the Maroaga Stream could not be considered as having “very clean” water (score >150), despite being located in an Environmental Protection Area. This may be due to the fact that the Maroaga Stream flows through the interior of the Maroaga Cave, which is inhabited by a considerable number of bats. Bat waste (guano) is deposited on Maroaga Cave floor and part of that guano enters the Maroaga Stream. The addition of the guano to the stream water likely altered the physicochemical properties of the water and, in turn, affected the macroinvertebrate community.
Nonetheless our results suggest that the Environmental Protection Areas policies are having a positive effect to ensure the conservation of the region. However, given the continued use of the site by the general public, further environmental control may be required to safeguard the environmental quality of the Maroaga Stream.
Nevertheless, given the increase in the number of urban settlements in Presidente Figueiredo in the recent years as well as new residential areas near to environmental conservation and protection areas, other watercourses located in these areas should also be monitored to assess their environmental health.
Our study, using the BMWP, indicated that the Maroaga Stream is characterized by a healthy macroinvertebrate community and thus with a “clean” environmental quality. The use of macroinvertebrates as bioindicators confirms their importance as a valuable monitoring tool in assessing freshwater ecosystems, highlighting their easy-to-use nature when surveying and assessing the health of watersheds in Amazonian environments. Bearing in mind the ecological and economical aspects of satisfactory environmental assessment, this approach has several features that can facilitate better water resource management; the BMWP Score System is easy to apply and has greatly reduced costs compared to physical and chemical analyses, many of which require transport of water samples to laboratories outside of the Amazon. Biological monitoring using macroinvertebrates is thus a suitable option that should be considered to meet the needs of Amazon watershed management and the taxa used in this study could help improve the evaluation of water quality in the streams in the Amazon.
The authors declare that there is no conflict of interests regarding the publication of this paper.