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Species diversity, abundance and environmental associations of loaches (Nemacheilidae and Balitoridae) in the central region of Thailand
Abstract
Environmental associations favorable for benthic loaches within the families Nemacheilidae and Balitoridae were the objective of this study that was conducted at 160 sites within five river systems: Southeastern, Mekong, Chao Phraya, Maeklong and Peninsula, in the central region of Thailand. Loaches in this study represented seven genera and 19 species; one each of Tuberoschistura and Homalopteroides, two Acanthocobitis, Homaloptera and Pseudohomaloptera, four Nemacheilus and seven Schistura. Fewest species (n = 3) were found in the Southeastern system with four species from each of the Mekong, Chao Phraya and Peninsula systems and 13 species in the Maeklong system. Species diversity within all systems was greatest for Schistura. Species and relative abundance of all fishes and of loaches varied directly and inversely, respectively, with river order for the two rivers in which this was examined. Abundances varied widely among species and sites with the most abundant species being Schistura aurantiaca, Schistura cf. sexcauda, Homalopteroides smithi and Acanthocobitis zonalternans. Species' distributions across all five river systems examined by canonical correlation analysis (CCA) varied significantly with six environmental variables. Of greatest significance were elevation and water temparature followed by water velocity, ambient oxygen, pH and Silica. Several adaptations for co-existence in fast flowing water are identified and discussed.
... Interaction of environmental variables in landscapes with biotic factors can result in environmental variations, which play a crucial role in shaping the distribution pattern of freshwater fishes within river ecosystem (Beamish and Plongsesthee, 2015). Studies have shown that environmental variables, along with other habitat features, are significant contributors towards species diversity and abundance (Beamish et al., 2008;Suvarnaraksha et al., 2012;Giacomazzo et al., 2023). ...
... Nemacheilids were found in temperatures ranging from 17.6-25.8°C similar to the range observed in prior studies by Suvarnaraksha et al. (2012) and Beamish and Plongsesthee (2015). The highest (8.5 ± 0.5) mean pH was recorded in Trongsa and lowest (7.4 ± 0.3) in Dagana. ...
... The loaches in Bhutan have been recorded mainly in the warmer regions ranging from South to the central region (Gurung and Thoni, 2015). Beamish and Plongsesthee (2015) and Tongnunui et al. (2016) conducted similar studies where lower elevation had significance in the species abundance and diversity indicating that loach species prefer warmer regions with the exception of some genera not present in this study. Absence of nemacheilid species in Trongsa could be attributed to higher elevation and colder temperatures. ...
Nemacheilids are freshwater fishes distributed mainly in the South–central regions of Bhutan and environmental variables seems to have significant effect on their distribution, abundance, and diversity.
However, existing knowledge and information about nemacheilid’s association with its environment is
limited in Bhutan. This study aimed to assess nemacheilid’s abundance and determine its association
with environmental variables in the South–central Bhutan. The study was conducted in the three major
river basins; Punatsangchhu, Mangdechhu and Amochhu, which comprises of Dagana, Sarpang, Tsirang,
Samtse and Trongsa district. The data were collected from each stream using systematic random sampling, with samples collected at 100 m intervals spanning up to 500 m long. A total of 56 plots were surveyed from which nemacheilids were found in 22 plots. Eleven species were identified in three genera.
The mean relative abundance of Schistura beavani was the highest in Dagana (9.5), Paracanthocobitis cf.
botia in Sarpang (18.8), and S. devdevi in Tsirang (35.0) and Samtse (15.3). The lowest mean relative
abundance of P. cf. abutwebi was in Dagana (3.3), Aborichthys sp.2 in Sarpang (6.8), S. scaturigina in
Tsirang (5.0) and Aborichthys sp.4 in Samtse (2.1). No nemacheilids were found in Trongsa. The canonical correspondence analysis (CCA) showed a significant association between species abundance and 11
environmental variables (p = 0.01, Monte Carlo test with permutation of 999). Elevation and temperature
were the most influential variables followed by total hardness, electrical conductivity, turbidity, pH, total
dissolved solids, salinity, ammonia, dissolved oxygen and chloride with lesser importance. It is recommended to explore additional variables, sites and anthropogenic activities to further elucidate the dynamics of nemacheilids abundance and formulate effective conservation strategies.
Keywords: Abundance, Bhutan, CCA, environmental variables, Nemacheilidae
... As recently as a decade ago, many balitorid species in Thailand have been revised and described as new species [17][18][19][20][21][22][23]. In contrast, the ecological studies of Thai balitorids are limited in the central regions, and to our best knowledge, there are only two publications in balitoridae distribution and their habitats [24,25]. Fish diet and feeding behavior have been previously reported on two species of balitorid fish, Homalopteroides smithi and Schistura kohchangensis [26][27][28], and there is no literature published on the reproduction of any balitorid fish in Thailand. ...
... Relative abundances of balitorid loach species were calculated by the maximum likelihood technique [24,25,34] that used an iterative process for estimating the abundance and capture probability from the removal method. For some small fish species not amenable to the maximum likelihood technique, and a conversion factor applied to adjust numbers was calculated from the estimated abundance of all captured fish divided by the total number of fish actually captured at the same site [33]. ...
... The highest balitorid diversity was found where water velocity was high and the streambed contains a high proportion of large particles [49][50][51], consistent with the dynamics of their pectoral and pelvic fin design and movement [22,41]. L. hasselti, the most widely distributed in the gravel to coarse sand and the most abundant species in this study, is morphologically adapted for a sand-dwelling life style, particularly predator escape [24,25]. Hence, we suggest that the distribution of L. hasselti appears to be more restricted to the sand-substratum of rivers. ...
Stream degradation increases with high anthropogenic activity and climate variability, while declines occur in biodiversity. However, few studies have been undertaken on tropical waterways, a major impediment to biodiversity conservation. The present study was conducted on 95 relatively pristine small streams in Eastern Thailand with 10 reasonably uncommon species of balitorid fishes. Measurements were made of 21 physical and chemical factors and the substrate particle size. Stepwise regression identified the direct importance of substrate particle size and nitrate on the species’ richness of balitorids, whereas its abundance was negatively related with iron concentrations. A Canonical Correspondence Analysis identified three fish groups: the 1st group was negatively correlated with ammonia and positively correlated with dissolved silica, the 2nd group was positively correlated with substrate particle size and negatively correlated with stream ambient temperature and ammonia concentration, and the 3rd group was negatively correlated with low dissolved silica, respectively. The results of this study may indicate the vulnerability of balitorids under climate warming and anthropogenic pressure that alter the water physicochemical factors and river degradation including the substrate type. Thus, a conservation framework should be provided regarding the limits for water temperature, ammonia, and iron in Thailand’s Water Quality Criteria to better protect its freshwater ecosystem. Balitorid is a potential bioindicator for evaluating the river temperature effect in combination with ammonia nutrient stressors as long as the way-of-life habits of the species are taken into account.
... The potential of such temperature increases acting in concert with other stressors such as habitat modifications, fish behavior, overexploitation of fish and invasions by non indigenous fishes are certain to impact freshwater fishes (Freitas et al., 2016). Earlier studies in Thailand have demonstrated clear and significant associations between ambient temperature and distribution of fishes in rivers where minimum and maximum of water temperature commonly range from 17.3 to 32.6ºC (Tongnunui and Beamish, 2009;Tongnunui et al., 2016;Suvarnaraksha et al., 2012;Beamish and Plongsesthee, 2015). Ambient river temperatures are rising. ...
Critical thermal maximum (CTmax) related positively with acclimation temperature between 20.0°C and a maximumthat varied with the four species; Devario acrostomus, Mystacoleucus chilopterus, Barbodes binotatus and Rasbora caudimaculata, between 30.0 and 35.0°C. Highest and lowest CTmax were 39.0±1.0°C at 35.0°C acclimation for B. binotatus and 34.6±0.5°C at 20.0°C for D. acrostomus, respectively. Thermal scope at 25.0°C acclimation was lowest at 26.8°C for D. acrostomus and, higher at 29.6, 29.7 and 30.1°C for M. chilopterus, R. caudimaculata and B. binotatus, respectively. Interestingly, the majority of tropical Thai fish and temperate species examined to date showed a similar maximum thermal tolerance from the mid to high 30s that almost certainly relates to temperature induction of HSP and their production. Global temperature increases predicted for Thai rivers and others in Southeast Asia during the latter portion of the current century are likely to exceed the thermal tolerance of many indigenous fishes with important losses in species diversity. © 2017, Thai Society of Higher Eduation Institutes on Environment. All Rights Reserved.
... Length of each site was approximately 35 times the estimated average width to capture all species present (Lyons 1992). Measurements of several physical and chemical variables were made at each site as described in Beamish & Plongsesthee (2015). ...
Garra fluviatilis is a new species described herein from the Kwai Noi, Mae Khlong basin, in the Thong Pha Phum District of Kanchanaburi Province in western Thailand. It is diagnosed by the following combination of morphological characters: well developed upper lip with unculiferous papillae, mottled pigmentation pattern, a pleated papilliferous fold at the junc-tion of the anterolateral lobe and anteromedial fold on the lower lip, 4-5 anal scales, relatively deep body, keeled nape, and a laterally straight anterior margin of the anteromedial fold. Based on shared apomorphic morphological characters, we hypothesize that the new species is most closely related to G. spilota in nearby Myanmar.
Fish species were collected by electrofishing from 96 sites, representing 79 species, in lightly exploited rivers in western Thailand. Significant chemical and physical environmental factors associated with species numbers and total fish abundance were identified using multiple linear regression. Total abundance correlated negatively with water depth and temperature (r = 0.4, p < 0.05), whereas species numbers correlated positively with river discharge and negatively with elevation (r = 0.6, p < 0.05). Chemical and physical factors that significantly influenced species distribution were determined using partial least squares regression analysis, (p < 0.05; axes 1, r = 0.8; axes 2, r = 0.85), and included elevation, river discharge, width and depth as well as ambient oxygen, alkalinity and pH. Fish were placed into four categories according to their habitat occupancy and abundance and termed; uncommon (54 species), common (16 species), even (8 species) and uneven (1 species), respectively.
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