This study was aimed at determining the performance of some indices and community attributes frequently used to assess river quality and test the role of macroinvertebrate taxa richness as element of bioindication in several coastal tropical streams of western Esmeraldas (Ecuador). In addition, a macroinvertebrate taxon list of this region was provided for the first time. Thirteen sampled points distributed across nine streams were selected for this study and nineteen parameters and attributes of bioindication were tested. The differences between nonimpact and impact places were evaluated mainly using one-way analysis of variance. Jackknife 2 and Clench were used to estimate the regional richness and the quality of the inventory, respectively. Seventy taxa (principally genus and family) of the main groups of macroinvertebrates were collected. Measured richness and family richness were the best metric followed by Biological Monitoring Working Party/Colombia (BMWP/Col), Odonata richness, Shannon-Weiner, and EPT richness (Ephemeroptera + Plecoptera + Trichoptera) indices. Only a slight right trend (Ephemeroptera, Trichoptera, and Chironomidae attributes) or incorrect performances (Average Score Per Taxon (ASPT) and % EPT) were showed by frequently used metrics. Finally, several recommendations were made about taxonomic level used, the ranks of quality of taxa richness, and the effort-results relationship in the field of bioindication.
Global change, population growth, and industrial development are currently exerting great impacts on natural ecosystems, especially on aquatic systems [
It is, therefore, necessary to use tools that can reveal the overall effect of human impact on the aquatic ecosystem [
The aim of this study was to test the performance of some of the most commonly used macroinvertebrate indices and community attributes to assess the water quality of coastal tropical streams of western Ecuador. In addition, for the first time, a macroinvertebrate taxon list of these systems will be provided for the above-mentioned fluvial systems and region. The main purpose of this paper is to establish more adequate techniques and recommendations using macroinvertebrate to devise a suitable management strategy for the aquatic resources (when the Ecuadorian legislation is applied). At the same time, there is also an interest in directly verifying the role of biodiversity as an environmental assessment measure. The majority of these evaluation techniques are based on the sensitivity and tolerance of macroinvertebrates to pollution. But we think and predict that in Ecuador, one of the areas with the greatest biodiversity in the world, other attributes relating to the community structure, such as taxa richness, should also have good performance.
Thirteen sampling points distributed across nine streams were selected for this study (Figure
Some characteristics of the streams included in the study.
Study area* | UTM** | Altitude (m) | Temp. (°C) | pH | Depth (cm) | Width (m) | Substrate type | Human impact*** |
---|---|---|---|---|---|---|---|---|
RV | 674195/103203 | 25 | 25 | 7.3 | 90 | 6 | Stony and sandy | IMP |
Ca | 659722/107374 | 80 | 25.3 | 7 | 40 | 5 | Stony | IMP |
T-I | 657039/103944 | 75 | 27 | 6.8 | 32 | 6.5 | Stony | IMP |
T-II | 657299/103546 | 81 | 26.5 | 7 | 30 | 6 | Stony | IMP |
T-III | 659162/099949 | 164 | 28 | 6.9 | 31 | 5 | Stony | Non-IMP |
T-IV | 659730/099523 | 195 | 28.2 | 7.2 | 30 | 4 | Stony | Non-IMP |
Tbz | 644956/087091 | 40 | 27 | 7.1 | 90 | 9 | Stony | Non-IMP |
Ch | 605058/082185 | 90 | 26 | 7 | 32 | 4.3 | Stony | Non-IMP |
EPb | 601471/083773 | 30 | 26 | 7.3 | 27 | 5.2 | Stony | IMP |
EPa | 602116/082477 | 49 | 25 | 7.2 | 31 | 4.1 | Stony | Non-IMP |
Q | 602108/079216 | 28 | 25 | 6.7 | 40 | 3.7 | Stony and sandy | Non-IMP |
SF | 609060/077145 | 45 | 25.8 | 7 | 42 | 7.9 | Stony | Non-IMP |
M | 609754/055039 | 25 | 24.7 | 6.8 | 28 | 4.4 | Stony | IMP |
Area of study and sample points. 1: Río Verde (RV), 2: Estero Camarones (Ca), 3: Estero Tachina I (T-I), 4: Estero Tachina II (T-II), 5: Estero Tachina III (T-III), 6: Estero Tachina IV (T-IV), 7: Estero Tabiazo (Tbz), 8: Estero Chipa (Ch), 9: Estero Plátano Bajo (EPb), 10: Estero Plátano Alto (EPa), 11: Estero Quinge (Q), 12: San Francisco (SF), and 13: Estero Mompiche (M).
Sampling at all the points was done once in October 2012 to coincide it with the dry season, the recommended period to carry out bioindication studies in this region [
We compared the performance of 19 parameters frequently used to assess river quality (Table
Values of the metrics measured in each stream.
Attribute | (RV) | (Ca) | (T-I) | (T-II) | (T-III) | (T-IV) | (Tbz) | (Ch) | (EPb) | (EPa) | (Q) | (SF) | (M) |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Measured richness | 19 | 14 | 20 | 16 | 28 | 32 | 30 | 25 | 17 | 32 | 28 | 32 | 23 |
Family richness | 15 | 13 | 16 | 13 | 22 | 24 | 22 | 19 | 15 | 26 | 21 | 22 | 20 |
Total abundance | 156 | 196 | 640 | 156 | 263 | 385 | 445 | 142 | 108 | 597 | 220 | 791 | 269 |
Shannon-Wiener | 4 | 2 | 3 | 3 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 3 | 4 |
BMWP/Col | 104 | 84 | 115 | 78 | 159 | 179 | 153 | 134 | 91 | 183 | 130 | 145 | 141 |
ASPT | 5 | 6 | 6 | 5 | 6 | 6 | 5 | 5 | 5 | 6 | 5 | 5 | 6 |
EPT richness | 13 | 8 | 9 | 11 | 9 | 11 | 10 | 7 | 10 | 9 | 4 | 5 | 10 |
EPT (%) | 7 | 4 | 9 | 8 | 9 | 11 | 13 | 11 | 5 | 10 | 9 | 10 | 10 |
Richness of Ephemeroptera | 6 | 3 | 6 | 7 | 6 | 5 | 9 | 6 | 3 | 5 | 8 | 8 | 6 |
Richness of Trichoptera | 1 | 1 | 3 | 1 | 2 | 5 | 4 | 4 | 2 | 5 | 1 | 2 | 4 |
Richness of Plecoptera | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
Richness of Odonata | 2 | 3 | 1 | 1 | 2 | 4 | 3 | 3 | 3 | 4 | 4 | 3 | 2 |
Richness of Coleoptera | 1 | 1 | 3 | 1 | 4 | 4 | 1 | 3 | 1 | 3 | 2 | 2 | 2 |
Percentage of Ephemeroptera | 25 | 4 | 68 | 51 | 29 | 25 | 34 | 32 | 9 | 14 | 60 | 60 | 53 |
Percentage of Trichoptera | 4 | 1 | 10 | 1 | 2 | 8 | 7 | 18 | 5 | 14 | 1 | 7 | 11 |
Percentage of Chironomidae | 20 | 1 | 13 | 4 | 34 | 25 | 36 | 15 | 11 | 12 | 5 | 4 | 5 |
Percentage of Odonata | 2 | 3 | 1 | 2 | 2 | 8 | 2 | 13 | 5 | 5 | 4 | 1 | 9 |
Percentage of Coleoptera | 6 | 26 | 2 | 9 | 15 | 19 | 6 | 14 | 44 | 9 | 5 | 6 | 10 |
Percentage of Plecoptera | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 2 | 0 | 0 | 0 | 0 | 0 |
% |
20 | 15 | 22 | 17 | 30 | 34 | 32 | 27 | 18 | 34 | 30 | 34 | 25 |
Abbreviations for study areas are as in Table
In addition to observed richness of macroinvertebrate, measures of estimated richness were calculated using nonparametric methods [
The responses of the several metrics and indices to assess the streams quality were graphically explored by means of box plots, showing mean value, standard error, and standard deviation of the metrics within each river category (IMP and Non-IMP). One-way analysis of variance (ANOVA) was applied to detect significant differences (
We collected 70 taxa from the 13 sampled points, finding high total abundance (4365 organisms). Table
Macroinvertebrate taxa and total number of individuals collected in the study area.
Class/order | Family | Genus | Number |
---|---|---|---|
Cl. Gastropoda | F. Thiaridae | 420 | |
F. Hydrobiidae | 29 | ||
F. Neritidae | 53 | ||
F. Planorbidae | 4 | ||
|
|||
Cl. Bivalvia | F. Sphaeriidae | 5 | |
F. Corbiculidae | 19 | ||
|
|||
O. Decapoda | F. Palaemonidae |
|
85 |
F. Atyidae |
|
2 | |
|
|||
O. Ephemeroptera | F. Leptophlebiidae |
|
630 |
|
80 | ||
|
2 | ||
|
11 | ||
|
5 | ||
F. Leptohyphidae |
|
101 | |
|
608 | ||
|
141 | ||
F. Caenidae |
|
6 | |
F. Baetidae |
|
4 | |
|
34 | ||
|
10 | ||
|
62 | ||
|
86 | ||
|
|||
O. Plecoptera | F. Perlidae |
|
8 |
|
|||
O. Odonata | F. Protoneuridae | 3 | |
F. Platystictidae |
|
12 | |
F. Megapodagrionidae | 1 | ||
F. Calopterygidae | 3 | ||
F. Coenagrionidae |
|
73 | |
F. Gomphidae |
|
4 | |
F. Libellulidae |
|
41 | |
|
1 | ||
Otros n.i. | 16 | ||
|
|||
O. Heteroptera | F. Naucoridae | 45 | |
F. Corixidae | 9 | ||
F. Gerridae |
|
71 | |
|
7 | ||
|
3 | ||
F. Veliidae |
|
77 | |
|
5 | ||
|
34 | ||
F. Hebridae | 6 | ||
|
|||
O. Megaloptera | F. Corydalidae | 2 | |
|
|||
O. Lepidoptera | F. Pyralidae | 15 | |
|
|||
O. Coleoptera | F. Psephenidae | 53 | |
F. Elmidae | 323 | ||
F. Hydrophilidae | 8 | ||
F. Ptilodactilidae | 7 | ||
F. Dryopidae | 37 | ||
|
|||
O. Trichoptera | F. Calamoceratidae |
|
5 |
F. Philopotamidae |
|
13 | |
F. Hydropsichidae |
|
188 | |
|
7 | ||
F. Polycentropodidae |
|
9 | |
F. Glossosomatidae |
|
31 | |
F. Hydroptilidae |
|
3 | |
|
74 | ||
F. Leptoceridae | 12 | ||
|
|||
O. Diptera | F. Chironomidae | Tanypodinae | 264 |
Orthocladiinae | 179 | ||
Chironominae | 194 | ||
F. Ceratopogonidae | 13 | ||
F. Limoniidae | Hexatomini | 47 | |
Eriopterini | 35 | ||
F. Empididae | 9 | ||
F. Sciomycidae | 1 | ||
F. Simulidae | 1 | ||
F. Stratiomyidae | 12 | ||
F. Psychodidae | 3 | ||
F. Dixidae | 3 | ||
F. Culicidae | 1 |
Figure
Response of several analyzed metrics to human impact on the studied streams. S: richness; %: percentage of abundance.
The nonparametric estimator Jack 2 predicted a high value of regional richness for the study area (93 taxa) (Figure
Observed and estimated regional richness in the study area. The nonparametric estimation was obtained by the nonparametric estimator Jackknife 2 (Jack 2).
The results showed the importance of taxa richness, the principal and simplest structural property characterizing the macroinvertebrate community [
On the other hand, metrics frequently used on bioindication studies, here only showed a slight right trend (Ephemeroptera, Trichoptera, and Chironomidae attributes) or incorrect performance (ASPT and % EPT). Both mayflies and caddisflies are sensitive to environmental stress [
Finally, to properly recommend the use of taxa richness as principal parameter of bioindication, we must mention three fundamental aspects. The taxonomic level used, the ranks of quality, and the effort-results relationship. It has been widely discussed what the best taxonomic level used for bioindication studies is [
This study seeks to make the baseline of use of taxa richness as bioindicators and presents the first taxon list of this region. The limited sample numbers that we were able to get, due to social conflicts and other risks of the study area, do not allow reaching conclusions that are widely extrapolated to other areas; consequently, simple speculations of the possible causes can be made. Nonetheless, we believe that these results are clear enough and statistically significant to recommend which attributes, from those largely used, and how they must be utilized as quality indicators for these streams. Through this study a great path is opened to research and establish the baseline to develop a multimetric index that includes metrics suitable for this region (principally taxa richness, EPT richness, S-W, and BMWP/Col or an own adaptation of this to study area) and the design of a sampling protocol including the most robust richness estimator, both nonparametric (Jack 2) and parametric (Clench), to establish sampling times and value ranks for the several used attributes.
The authors declare that there is no conflict of interests regarding the publication of this paper.
This research was funded by the CID (Research and Development Center) (PUCESE).