Hindawi Publishing Corporation Psyche Volume 2015, Article ID 912451, 7 pages http://dx.doi.org/10.1155/2015/912451 Research Article Diversity and Distribution of Aquatic Insects in Streams of the Mae Klong Watershed, Western Thailand Witwisitpong Maneechan and Taeng On Prommi Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand Correspondence should be addressed to Taeng On Prommi; [email protected] Received 27 July 2015; Revised 26 October 2015; Accepted 29 October 2015 Academic Editor: Nguya K. Maniania Copyright © 2015 W. Maneechan and T. O. Prommi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The distribution and diversity of aquatic insects and water quality variables were studied among three streams of the Mae Klong Watershed. In each stream, two sites were sampled. Aquatic insects and water quality variables were randomly sampled seven times in February, May, September, and December 2010 and in January, April, and May 2011. Overall, 11,153 individuals belonging to 64 families and nine orders were examined. Among the aquatic insects collected from the three streams, the order Trichoptera was most diverse in number of individuals, followed by Ephemeroptera, Hemiptera, Odonata, Coleoptera, Diptera, Plecoptera, Megaloptera, and Lepidoptera. The highest Shannon index of diversity of 2.934 and 3.2 was recorded in Huai Kayeng stream and thelowest was in Huai Pakkok stream (2.68 and 2.62). The high diversity of insect fauna in streams is an indication of larger microhabitat diversity and better water quality conditions prevailing in the streams. The evenness value was recorded as high in most sites. The high species diversity and evenness in almost all sites indicated good water quality. 1. Introduction parameters such as increased sedimentation and changes in flow [11]. In lotic environments, aquatic insects are important elements In this work, three streams in the Mae Klong Watershed in the ecological dynamics [1], playing an important role in wereselected.Thesestreamsareusedfordomesticactivities the cycle of materials and in trophic transfers [2–5]. The including drinking, cooking, bathing, and fisheries. It is understanding of distribution patterns in communities is one therefore important to preserve these water resources and of the main aims in ecology [6]. A multiplicity of factors maintain the biotic integrity of these ecosystems. Such man- regulates the occurrence and the distribution of aquatic agement requires basic knowledge such as the distribution of insects, the most important being the current (velocity), the aquatic communities among stream habitats. The aim of temperature, altitude, season, total suspended solids, and this study was to describe the composition of aquatic insects vegetation [7]. Other factors which affect the occurrence of at different stations of the studied streams. The identification these benthic fauna include substrates, pH, dissolved oxygen, of species and their distribution patterns provide more infor- availability of food, turbidity, conductivity, and competition mation for monitoring and conserving these ecosystems. [8]. Changes of these environmental factors in streams can be used in biomonitoring and degraded aquatic environments [9, 10]. Thus, the nature of this distribution provides an initial 2. Materials and Methods insight into the types of ecological processes that regulate populations and assemblages. For example, the distribution 2.1. Study Area. The Mae Klong Watershed is the most of aquatic insects among stream habitats reflects, to some important watershed in western Thailand. The upstream degree, the distribution of benthic resources (e.g., food, watershed area consists of two main rivers, namely, Khwae oxygen, and predators) and provides information about how Noi and Khwae Yai. The rivers run into the Khao Laem and communities might respond to changes in environmental Srinagarind Dam located in the upper region of Mae Klong 2 Psyche Site Stream Mae Klong River Boundary of Thailand 5 Boundary of Province 8 6 Mae Klong Watershed 2 1 7 (km) 4 10 0 10 20 30 3 N Number Site name 9 1 Huai Pakkok 1 2 Huai Pakkok 2 3 Huai Kayeng 1 4 Huai Kayeng 2 5 Huai U long 1 10 6 2 Huai U long 11 7 Pilok Wire 8 Wachiralongkorn Dam 9 Mae Klong Dam 10 Ratchaburi 11 Samut Songkhram Figure 1: Map of Mae Klong Watershed showing the sampling sites, namely, Huai Pakkok, PK1 = 1 and PK2 = 2; Huai Kayeng, KY1 = 3 and KY2 = 4; and Huai U Long, UL1 = 5 and UL2 = 6. Watershed. The rivers joint in Kanchanaburi Province, which 250 m mesh). At each sampling site, a stretch of approx- is considered downstream, flow through Ratchaburi Province imately 50 m was chosen for collection of samples from andentertheGulfofThailandinSamutSongkhramProvince. the three target habitats: riparian vegetation, leaf litter, and Six sampling sites in three streams (upper and lower in each low gradient riffles and pools. The sampling time ateach stream)werechoseninthisstudy.Thesestreamswereinthe habitat was 3 min. In each sampling period, three replicate upstreamsectionofKhwaeNoiRiverbeforeflowinginto samples were collected at each station and placed in white Khao Laem Dam (Figure 1). These three streams are, namely, trays for sorting. The content of each sample was transferred Huai Pakkok, PK1 and PK2; Huai Kayeng, KY1 and KY2; and into properly labelled plastic containers, preserved in 80% Huai U Long, UL1 and UL2. ethanol, and taken back to the laboratory for analysis. In thelaboratory,aquaticinsectsweresortedandidentifiedto the family level using taxonomic keys [12–14]. All the sorted 2.2. Sampling and Identification of Aquatic Insects. To deter- samples were kept in properly labelled vials containing 80% mine the distribution of aquatic insect taxa, six sampling ethanol. sites in three streams (upper and lower in each stream) were chosen in this study. Seven samplings were performed in February, May, September, and December 2010 and in 2.3. Environmental Variables. Three replicates of selected January, April, and May 2011. Aquatic insects were collected physicochemical water quality parameters were recorded using aquatic D-frame aquatic kick net (30 × 30 cm frame, directly at the sampling sites including pH, air temperature Psyche 3 Diptera Ephemeroptera (2,193 individuals; 19.66% of total abundance), Hemiptera 5.81% (1,707 individuals; 15.31% of total abundance), Odonata (1,260 Trichoptera 19.66% individuals; 11.30% of total abundance), Coleoptera (978 indi- 33.98% Odonata 11.30% viduals; 8.77% of total abundance), Diptera (648 individuals; 5.81% of total abundance), Plecoptera (514 individuals; 4.61% of total abundance), Megaloptera (34 individuals; 0.30% of total abundance), and Lepidoptera (29 individuals; 0.26% of total abundance) (Figure 2; Table 1). The aquatic insects of Huai Pakkok stream (PK1 and PK2) constituted 50 families and 46 families, while 49 families and 46 families were recorded in Huai Kayeng stream (KY1 and KY2). The aquatic Lepidoptera Plecoptera insects recorded from Huai U Long stream (UL1 and UL2) 0.26% 4.61% were represented by 41 and 49 families, respectively (Table 1). Megaloptera Coleoptera Hemiptera Table 1 showed the species diversity indices. The highest 0.30% 8.77% 15.31% Shannon index of diversity of 2.934 and 3.2 was recorded in Figure 2: Composition of aquatic insect orders of the three streams Huai Kayeng stream (KY1 and KY2) and the lowest was in in the Mae Klong Watershed during a period of seven months. Huai Pakkok stream (HK1 and HK2) (2.68 and 2.62), indicat- ing the presence of a higher diversity of aquatic insects in lotic ecosystems.Thediversityofinsectsinaquaticecosystems tends to increase with increased nutrients and these optimum (AT), water temperature (WT), dissolved oxygen (DO), environmental conditions favour their abundance in this total dissolved solid (TDS), and electrical conductivity (EC). habitat [17]. The high diversity of insect fauna in streams Water samples from each collecting period were stored in is an indication of larger microhabitat diversity and better polyethylene bottles (500 mL). Ammonia-nitrogen (NH3-N), 3− water quality conditions prevailing in the streams (Table 2) orthophosphate (PO4 ), nitrate-nitrogen (NO3-N), sulfate 2− [18]. Their abundance has been associated with the presence (SO4 ), and turbidity (TUB) were determined in accordance of high food quality, stable water flow, and stable substrata with the standard method procedures (APHA et al., 1992) common in these habitats [17]. [15]. Alkalinity (ALK) was measured by titration. The evenness value in the present study was recorded as high in almost all the sites, indicating a relatively even 2.4. Data Analyses. The aquatic insect abundance and taxo- distribution of taxa in the stream. The highest species diver- nomic richness () were estimated for each sample. Ecolog- sityandevennessinalmostallthesitesareanindicationof ical indices, including the Shannon-Wiener diversity ( ), good water quality [18]. The high scores of diversity indices, Simpson’s diversity index (), and Evenness ()indices, such as those of the Shannon-Wiener index and Simpson’s were determined for each sampling site [16]. A principle index, indicate that clean or unpolluted rivers support more component analysis (PCA) was performed using environ- diverse taxa, thus making them useful for detecting