Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 October 2022 | 14(10): 21976–21991
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.7979.14.10.21976-21991
#7979 | Received 17 April 2022 | Final
received 20 May 2022 | Finally accepted 11 October 2022
Environmental
factors affecting water mites (Acari: Hydrachnidia) assemblage in streams, Mangde
Chhu basin, central Bhutan
1 merman.gurung93@gmail.com
(corresponding author), 2 cdorji.cnr@rub.edu.bt, 3 dbgurung.cnr@rub.edu.bt, 4 harry.smit@naturalis.nl
Abstract: Water mites were sampled from 15 tributary
streams of Mangde Chhu
river in Zhemgang and Trongsa districts, Central
Bhutan in pre-monsoon (April–May) and post-monsoon (October–November) of 2021.
A total of 802 individuals were collected belonging to seven families and 15
genera. The accumulation curve suggests that the sampling efforts were adequate
to give a proper overview of genera composition for elevations 500–2,700 m. Eleven genera—Aturus,
Kongsbergia, Woolastookia, Atractides, Hygrobates, Lebertia, Piona, Sperchonopsis, Monatractides, Pseudotorrenticola and Testudacarus—and
five families—Aturidae, Hygrobatidae,
Lebertiidae, Pionidae, and Protziinae—are new records for Bhutan. Independent sample t-tests
of genera richness (t, (26) = 0.244, p = 0.809); genera evenness
(t, (26) = 0.735, p = 0.469); Shannon diversity index (t, (26)
= 0.315, p = 0.755) and dominance (t, (26) = -0.335, p =
0.741) showed no significant differences between pre- and post-monsoon
assemblages. Species abundance was also not significantly different (t, (28)
= -0.976, p = 0.330). Principal component analysis indicated that the
diversity of water mites is negatively associated with several environmental
variables including chloride (r = -0.617), ammonia (r = -0.603),
magnesium hardness (r = -0.649), total hardness (r = -0.509),
temperature (r = -0.556), salinity (r = -0.553), total dissolved
solids (r = -0.509) and electrical conductivity (r = -0.464).
Diversity was positively correlated with altitude, mainly caused by the higher
Palaearctic genera diversity. Similarly, Pearson’s correlation test showed that
there was significant negative correlation between mite abundance and the water
physio-chemical parameters salinity (r = -0.574, p = 0.032),
electrical conductivity (r = -0.536, p = 0.048), total dissolved
solids (r = -0.534, p = 0.049), total hardness (r =
-0.621, p = 0.018), and chloride concentration (r = -0.545, p
= 0.036), indicating sensitivity of water mites to pollution.
Keywords: Biotic assessment, climate change, fresh
water, macroinvertebrates.
Editor:
J.G. Manjunatha, Field Marshal K M Cariappa College, Madikeri, India. Date
of publication: 26 October 2022 (online & print)
Citation: Gurung, M.M., C. Dorji,
D.B. Gurung & H. Smit (2022). Environmental factors
affecting water mites (Acari: Hydrachnidia)
assemblage in streams, Mangde Chhu
basin, central Bhutan. Journal of Threatened Taxa 14(10): 21976–21991. https://doi.org/10.11609/jott.7979.14.10.21976-21991
Copyright: © Gurung et al. 2022. Creative Commons Attribution 4.0 International License. JoTT allows
unrestricted use, reproduction, and distribution of this article in any medium
by providing adequate credit to the author(s) and the source of publication.
Funding: The research
project was made possible by the grants provided by foundation Pro Acarologia Basiliensis
(Basel), and the National Geographic Society (NGS-72271C-20).
Competing interests: The authors declare no competing
interests.
Author details: Mer Man Gurung is a researcher keen to
study aquatic diversity, impact of climate change and anthropogenic activities
on freshwater ecology. He is passionate to study dragonflies and damselflies of
Bhutan, water mites and its relationships with water and environmental factors.
Currently working on odonates of southern Bhutan and
protected areas. Cheten Dorji is
lecturer and a researcher affiliated to College of Natural Resources, Royal
University of Bhutan. Currently he is studying phylogeography
of rare and endemic Cave Wata of Bhutan and New
Zealand. Dhan B. Gurung is a professor in College
of Natural Resources, Royal University of Bhutan. He is a pioneer of freshwater
fishes of Bhutan with substantial contributions. His interest is not limited to
fishes, he has also contributed significantly to Orchids of Bhutan. Harry Smit is associate researcher at
Naturalis Biodiversity Center, Netherlands. He works worldwide on the
systematics of water mites and has substantial contribution on water mites
of the world.
Authors contributions: MMG— carried out fieldwork and drafted the manuscript,
CD—carried fieldwork with first author, DBG—reviewed the manuscript,
HS—reviewed the manuscript.
Ethical standards: The research project with permit no. 17703966556045F2C2BFD63 was
approved by Ugyen Wangchuck
Institute for Conservation and Environmental Research (UWICER), Lamaigoenpa, Bumthang Bhutan.
Specimen collections and preservation were done following standard protocols as
detailed in the methods section.
Acknowledgements: The fieldwork of this research was made
possible by grants of the foundation Pro Acarologia Basiliensis (Basel), and the National Geographic Society
(NGS-72271C-20) for the project titled ‘Exploring the invertebrate diversity of
the last virgin rivers of Bhutan, the Eastern Himalayas’. The first author is
thankful to Naturalis Biodiversity Centre (Leiden), the Netherlands for
providing field equipment and references. In particular we are indebted to
Vincent J. Kalkman (Naturalis Biodiversity Center)
for critically reading a first draft of this paper. We are also thankful to the
chief forest officer of Jigme Singye Wangchuck National Park (JSWNP) for granting permission to
survey freshwater mites along Mangde Chhu basin and Ugyen Wangchuck Institute for Conservation and Environmental
Research (UWICER) for the permit. We are thankful to Mr. Karma C. Dendup, forest officer (FO), JSWNP; Mr. Ratan
Giri, senior forester, JSWNP and Mr. Namgay Dorji, deputy ranger,
JSWNP for their selfless field escorts. We acknowledge Mr. Sonam Moktan (Lab tech.), College of Natural Resources, Royal
University of Bhutan. First Author is grateful to IDEAWILD as well for the
equipment support.
INTRODUCTION
Most lotic freshwater habitats in Bhutan, such as streams, springs, and
rivers, harbora rich aquatic diversity of
macroinvertebrates and fishes (Gurung et al. 2013; Gurung & Dorji 2014; Wangchuk & Dorji
2018; Dorji et al. 2020; Rai et al. 2020; Norbu et al. 2021). These habitats are also the major
sources of drinking water in Bhutan, thus their preservation is essential for
both the conservation of biodiversity as well as the economic well-being of
Bhutanese (Dorji 2016b). Lotic freshwater systems
are, however, under pressure due to anthropogenic pollution and climate change
(Xu et al. 2009; Tsering et al. 2010). Thus biotic
assessment of these habitats is essential to understand the health of the
water.
Water mite are greatly influenced by water parameters and environmental
factors (Stryjecki et al. 2016; Savić
et al. 2022). Abundance of water mites is negatively influenced by water
temperature and velocity (Stryjecki et al. 2018),
with temperature being the major factor that influences distribution of Hydrachnidia along altitudinal gradients. Mite abundance is
positively impacted by pH (range 7.3–8), dissolved oxygen, and total hardness (Stryjecki et al. 2016; Negi et al. 2021). Seasonality also
impacts mite in freshwater habitats. According to Negi et al. (2021), Hydrachnidia abundance was maximum during pre-monsoon
(January) and minimum in monsoon (July).
Water quality monitoring is commonly done in two ways: a) determination
of physico-chemical properties of the water and b)
biotic assessment of aquatic organisms. In most cases, physico-chemical
assessment of water only gives an indication of the water quality at the moment
when the sample was taken, and poor water quality or pollution during other
parts of the year might go unnoticed. Results based on biotic assessment, in
contrast, give a direct indication of water quality throughout the year, as
poor water quality or pollution will be reflected in the faunal composition (Ofenbock et al. 2010; Wangchuk & Dorji
2018; Rai et al. 2020). For this reason, biological water monitoring is at
least as valuable for freshwater management as physico-chemical
monitoring.
Aquatic meiofauna such as water mites are excellent bioindicators of
water quality (Smit & Van Der Hammen 1992; Miccoli et al. 2013; Wieçek et al. 2013; Goldschmidt
2016). They are present in both lotic and lentic habitats (Smith et al. 2001)
at a large range of elevations (Mani 2013). Thus far, water mites have been
ignored during freshwater habitat assessments in Bhutan and other regions,
which have focused on other macroinvertebrates (Ofenböck
et al. 2010; Giri & Singh 2013; Patang et al. 2018; Wangchuk & Dorji
2018; Rai et al. 2020) and fishes (Gurung et al. 2013; Wangchuk et al. 2018; Dorji et al. 2020; Norbu et al.
2021). Neglect of water mites as bioindicators can partially be explained by
their diminutive size and complex life cycle (Goldschmidt 2016).
A few aquatic diversity assessments in Bhutan recorded water mites and
in all cases they were lumped together as Hydrachnidia
or Acari (Ryder et al. 2015; Currinder
2017; Wangchuk & Dorji 2018). However, recent
faunistic studies have described and recorded several new species of water
mites from Bhutan (Pešić et al. 2022a; Smit &
Gurung 2022; Smit et al. 2022; Pešić et al. 2022b)
and currently there are 30 species documented from Bhutan (Gurung et al. 2022).
Several major biotic assessment studies in Bhutan did not record mites (Dorji 2016a; Rai et al. 2020) despite fulfilling all the
criteria (Resh 2008) for use as bioindicators,
including: (1) wide geographical and habitat distribution, (2) high species
richness, (3) relatively sedentary to a localized microhabitat (ideal for
examination of contamination spatially), (4) long life cycle for long-term integration
during the biotic assessment, (5) easy and cost effective sampling, (6) clear
and well known taxonomy, (7) sensitive to contamination, (8) availability of
experimental data on effects of contamination for different species (Di Sabatino et al. 2002; Smith et al. 2010; Miccoli et al. 2013; Goldschmidt et al. 2016). Therefore,
during biotic assessment of freshwater habitats in Bhutan, water mites should
be regarded as important for monitoring.
One of the reasons that water mites have not been used as bioindicators
in Bhutan is that basic data on identification and distribution is largely
absent for the Himalayan region (Pesic & Smit
2007; Gerecke & Smit 2022). Identification to
species level is problematic, and even identification to genus level takes some
experience (Smit 2020). The key to the genera of the world recently published
by Smit (2020) makes identification to genus level easier, but papers like Gerecke & Smit (2022) describing species new to science
are needed to enable people to identify material to species level. Taxonomic
progress is partially hampered by the complex life cycle of water mites that
includes pre-larval stage, parasitic larva, protonymph (i.e., initial resting
stage), deutonymph (free living form), tritonymph (second resting stage), and
the final adult stage (Di Sabatino et al. 2000).
Besides problems with identification, another reason for the lack of the
use of water mites as bioindicators is the lack of ecological studies for the
Himalayan region. Although the link between water mite assemblages and water
quality has been studied at least some times in other parts of the world basic
studies on this subject from Bhutan and surrounding countries are lacking. A
study on this subject would be of interest, especially as Bhutan is part of the
border between the Oriental and Palaearctic region,
with the species composition above 1,000 m elevation in general being of Palaearctic origin while that below 1,000 m elevation has a
more Oriental affinity (Rasaily et al. 2021).
In 2021 and 2022, the first author studied water mites in Bhutan with
the aim of producing new faunistic and taxonomical data providing basic
information on water mite assemblages and water quality. The present paper is
part of this larger study, and describes the patterns in composition and
diversity in lotic waters along an altitudinal gradient. We use this
information to address three questions: (1) is there a difference in water mite
diversity, abundance and assemblages between pre- and post-monsoon? (2) which physico-chemical parameters correlate with the presence and
abundance of water mite genera? And (3) is there a gradient from a largely
Oriental fauna to a more Palaearctic fauna rising from
500 m to 2,700 m?
Material and methods
Study
area
Mangde Chhu river basin has catchment area of 7,380 km2,
annual flow of 11,797 million m2, 1,173 high-altitude wetlands (such
as brooks, lakes, marshy areas), and 287 glaciers (NEC 2016). Mangde Chhu River originates from
Gangkhar Puensum, passes through Trongsa, and exits
Bhutan through Zhemgang as Manas
River after joining with Drangme Chhu
River. Fifteen perennial tributary streams of Mangde Chhu River were selected for this study ranging in altitude
from 500 m to 2,700 m (Figure 1). A multi-stage sampling method (Gascho-Landis & Stoeckel
2016) was adopted for classification of the study area into three groups along
the altitudinal gradient to study the effect of altitude on the water mite
composition, namely between 500–1,000 m (low), 1,001–1,999 m (mid) and
above 2000 m (high). Ammonia concentration ranged 0.04±0.002–662±78.4, calcium
hardness 40.1±5.12–1.66±0.12, magnesium hardness 30.2±6.49–8.46±0.12, total
hardness 70.3±11.05–22.4±0.08, chloride 128.2±19.6–32.5±3.41, electrical
conductivity 48.8±0.43–33.4±1.51, dissolved oxygen 15.7±0.66–103.5±0.42, pH
7.67±0.05–14±3.07, salinity 19.3±0.14–7.21±0.08, total dissolved solids
34.6±0.16–50.7±0.25, temperature 14.6±0.54–44.6±0.64, and turbidity
0.62±0.20–46.5±3.41. Sampling was carried out in pre-monsoon (April–May) and
post-monsoon (October–November), 2021.
Sampling
sites and habitat description
MG1: Maidagang Chhu, Tingtibi, Zhemgang district, (27.12761°N, 90.71560°E,
altitude 554 m, 24 April 2021; 20 October 2021) flows through a dense bushy
vegetation and eventually drains into Mangde Chhu River. There is an agriculture field and a farm road
above the confluence. Stream substrates mostly consist of cobbles with sand and
rocks which often obstruct water forming small pools.
MG2: Berti Chhu, Berti, Zhemgang district (27.16264°N, 90.66003°E,
altitude 590 m, 26 April 2021; 25 October 2021) flows through a narrow valley
in deep forest. Before reaching the confluence, it passes the Berti community. The stream is adopted by the community for
legal fishing in producing smoked fish (Nyea
Dhosem). Berti Chhu substrates are predominantly composed of cobbles with
sand. Riparian vegetation included ferns, climbers, and lowland grasses. Most
of the sites had riffles, pools, and cascades. Water was heavily inhabited by
fish fingerlings such as that of Garra spp.
and Danio rerio.
MG3: Bipgang Chhu, Berti-ecolodge,
Zhemgang district (27.15729°N, 90.66721°E,
altitude 586 m, 28 April 2021; 25 October 2021). Bipgang
Chhu flows along the mountain base parallel with the
road connecting Tingtibi and Berti
fishing community and it connects with Mangde Chhu River below Berti Eco-lodge
camp. Stream riparian vegetation was covered by dense shrubs and grasses and
the substrate was sandy with high debris content. The stream was inhabited
abundantly by fishes. The natural water habitat was impacted due to frequent
cleaning of the stream by the eco-lodge staff clearing the way for fish
movement.
MG4: Takabi Chhu, Tingtibi, Zhemgang district (27.14782°N, 90.68833°E,
altitude 543 m, 31 April 2021; 26 October 2021) stream flows through a steep
mountain valley and has a high-water current. Riparian vegetation was mostly
trees with underlying grasses. Substrate was mostly cobbles and sand. Rocks
often obstruct the water forming pools and cascades.
MG5: Dakpay Chhu, Tingtibi, Zhemgang district (27.14621°N, 90.69220°E,
altitude 539 m, 01 April 2021; 27 October 2021) flows through a thick
vegetation with high water current. Water was murky. Substrate was rocky with
cobbles and had less sand. Riparian vegetation had dense grasses under tall
tree canopy. The submerged grasses along the streams formed a potential habitat
for mites.
MG6: Yumrung Chhu, Langthel,
Trongsa district (27.36691°N, 90.53618°E,
altitude 1,092 m, 02 May 2021; 28 October 2021) flows along abandoned mineral
mining sites. Towards the confluence, the stream passes by the Mangde Chhu hydropower house and
an automobile workshop. The stream was heavily disturbed due to dumping of
gravel and soils from mining of the cliff. Downstream of the river was greatly
impacted by the hydropower plant and an automobile workshop.
MG7: Wana Chhu, Langthel,
Trongsa district (27.34964°N, 90.58144°E,
altitude 1,139 m, 03 May 2021; 29 October 2021): this small stream flows
through the thickly vegetated valley by the side of the paddy field. The water
was murky, and stream substrate was sandy clay with debris. Riparian vegetation
was dominated by Ageratina adenophora (invasive species), Alnus
nepalensis, Artemisia vulgaris and climbers.
MG8: Dangdung Chhu, Langthel,
Trongsa district (27.33461°N, 90.59562°E,
altitude 1,039 m, 05 May 2021; 30 October 2021) is a fast-flowing montane
stream with high water current. Sampling was conducted at the divergent point
which had low current water flow. Substrate composed of mostly cobbles and
sand.
MG9: Kartigang Chhu, Langthel,
Trongsa district (27.27896°N, 90.63088°E,
altitude 1,456 m, 07 May 2021; 01 November 2021) flows through a landslide
washed stream beds with greyish sediments. Substrate was mostly pebbles and
cobbles with minimum sand. Surrounding vegetation was sparse with trees having
less undergrowth. Water was whitish in color due to white mud bed.
MG10: Chumpigang Chhu, Langthel,
Trongsa district (27.31608°N, 90.58071°E,
altitude 1,018 m, 08 May 2021; 02 November 2021) stream flows through a deep
forest along a narrow valley. Rock obstructs the water flow creating falls,
cascades and pools. Riparian vegetation had grasses and stream substrate was
mostly cobbles with sand.
MG11:Waterfall stream (name unknown), Trongsa
district (27.30171°N,
90.58711°E,
altitude 1,195 m, 09 May 2021; 03 November 2021) flows through a mountain gorge
forming water falls; the stream substrate mostly composed of cobbles and sand
with high debris content.
MG12: Nika Chhu, Trongsa
district (27.52601°N,
90.29947°E,
altitude 2,609 m, 10 May 2021; 04 November 2021); water current was low despite
the stream being quite large. Water temperature was lowest in this stream.
Substrates mostly composed of cobbles and sand mixed with debris. Riparian
vegetation was mostly shrubs with tall Pinus and hemlock tree canopies.
MG13: Rukhubji Chhu, Pelela,
Trongsa district (27.51174°N, 90.29711°E,
altitude 2,587 m, 12 May 2021; 05 November 2021) flows through a valley covered
with thick high-altitude conifers and underlying shrubs, the color of the water
is darker throughout the year. Stream substrate was rocky covered by layers of
algae and mosses. The stream connects with Nika Chhu
River nearby an old Chorten (Buddhist stupa).
MG14: Chuserbu, Trongsa district (27.50246°N, 90.31782°E,
altitude 2,666 m, 13 May 2021; 06 November 2021) flows through dense riparian
bamboo forest with tall tree canopies, substrate were mostly sand. The stream
was pristine and there were fewer disturbances with no settlements upstream.
MG15: Khabab Chhu, Chendebji, Trongsa district (27.48492°N, 90.33490°E,
altitude 2,500 m, 14 May 2021; 07 November 2021) flows throw a gentle slope.
Cobbles and pebbles mixed with sand and debris make up the stream substrate.
Plastic waste was dumped along the stream and wastewater from the village is
also discharged into the stream. In the post-monsoon, the stream was severely
damaged by a flashflood, and there were huge depositions of sand and rocks
washed from upstream.
Environmental
characterization
At all localities, physico-chemical parameters
of water were measured following APHA (2017) standards. Dissolved oxygen (mgL-1),
temperature (°C), electrical conductivity (μScm-1),
pH, and total dissolved solid (mgL-1) were analyzed on site using
HANNA multiparameter digital probe (Code HI2004-02, S/N C05031A5). Water
samples were collected and stored in freezer (at 5°C) and brought to lab
for further analysis. Salinity was measured using salinity meter, turbidity
(NTU) was measured following Nephelometric method, water hardness (mgL-1)
following EDTA method, Chloride (mgL-1) following Argentometric
method (Korkmaz 2001) and ammonia (mgL-1)
following Phenate method (Park et al. 2009).
Mites sample collection and preservation
Water mites were collected following quantitative approach as described
by Gerecke et al. (2007) with a uniform sampling
duration of 10 minutes on each station. In each stream, collections were
carried out at four substations using D-frame kick net (mesh size 250-μm and frame size 30cm) with 100 m distance
between the sampling substations. The stream bed was dislodged with foot and
the materials carried by water current were collected by keeping the D-frame
net downstream (‘kick-sampling’). Submerged aquatic plants along the periphery
of the streams were disturbed mechanically and the material was collected
downstream with the D-frame kick net. The material collected was transferred
into a white tray, letting the substrate settle for a few minutes and the mobile
mites were picked using a plastic pipette through visual observation. The
specimens collected were preserved in Koenike-fluid
(20% glacial acetic acid, 50% glycerin and 30% distilled water) for
morphological study and a part of the material was also stored in ethanol (90%)
for future molecular study.
Identification
Water mites were identified through morphological examination of
specimens under a high-resolution microscope Olympus-829187. A Nikon D5600
DSLR-camera attached with NDPL-2(2X) converter was fixed on the eye piece of
the microscope to take photographs of the specimens. Identification of the
water mites were done using keys of Cook (1967) and Smit (2020). Following an
identification by the first author, all identifications were confirmed by H.
Smit.
Statistical
test
The preliminary data processing was done using Microsoft Excel
Professional Plus 2016. Genera composition curve was computed using PC-ORD v5.1
(Grandin 2006). Hydrachnidia genera diversity was
examined using Shannon’s diversity index, H’ = Σ(Pi)Ln(Pi)
(where Pi is the proportion (n/N natural log), and Σ is the sum of the
equations). Genera richness was calculated using the equation: (SR)
= (S-1)/LogN (where, S is sum of the
genera, N is sum of all genera). Genera evenness, and genera
dominance (Simpson’s index; D) was calculated using the formula, D = Σpi2 (where, pi is the
proportion of genera in a community (pi =ni/n),
Σ is sum of the equations). Means, standard deviations, total abundance and
relative abundance values were calculated for all sites. Independent sample t-test
was performed to compare the pre- and post-monsoon diversity indices. Before
performing this test, Shapiro–Wilk’s test was done in R-software to test if the
data were normally distributed.
Principal component analysis (PCA) between environmental variables and
the abundance of different water mite genera was performed using the distance
measure of relative Sorensen (Bray-Curtis) method separately for both pre- and
post-monsoon in PC-ORD v5.1 software. Pearson’s correlation test was used to
compute the relationship between the environmental variables and water mite
assemblages.
Results
A summary of environmental factors in the
pre- and post-monsoon period is given in Table 1. In total of 802 water mites
were collected belonging to 15 genera with an average of five genera with 26
specimens per location in pre-monsoon and five genera with 29 specimens per location
in post-monsoon (Table 2). The mite genera accumulation curve for both (A) pre-
and (B) post-monsoon suggests that the sampling efforts were adequate to
characterize the water mite genera composition in the study area (Figure 2).
Twelve genera, i.e., Atractides, Aturus, Hygrobates,
Kongsbergia, Lebertia,
Limnesia Monatractides,
Piona, Protzia,
Pseudotorrenticola, Sperchonopsis,
and Woolastookia (Image 1 & 2) from eight
families (i.e., Aturidae, Hygrobatidae,
Lebertiidae, Limnesiidae, Pionidae, Hydryphantidae, Sperchontidae, Torrenticolidae)
are recorded new to Bhutan. Pre-monsoon (491) mites were more abundant than
that of post-monsoon (311), dominated by Monatractides
(162) and Torrenticola (109) in
respective seasons (Table 2).
Diversity
indices
Diversity indices such as genera richness,
evenness, Shannon diversity index and dominance of 15 streams were calculated
(Table 3) and compared (Figure 3) for two seasons. There was a significant
positive correlation between pre- and post-monsoon genera diversity (r =
0.693, p = 0.004), evenness (r = 0.704, p = 0.003)
and dominance (r = 0.605, p = 0.017) but genera richness (r = 0.479,
p = 0.71) was not significantly correlated for the two seasons (Table
4). Independent sample t-test showed no significant differences between
pre-monsoon and post-monsoon diversity indices. Genera richness for the pre- (M
= 4.71, SD = 1.72) and post-monsoon (M = 4.57, SD = 1.34)
was not significantly different (t (26) = 0.244, p = .809).
Likewise, for genera evenness for pre- (M = 0.800, SD = 0.139)
and post-monsoon (M = 0.758, SD = 0.163); (t (26) = 0.735,
p = 0.469); Shannon diversity index for pre- (M = 1.18, SD
= 0.389) and post-monsoon (M = 1.14, SD = 0.366); (t (26)
= 0.315, p = 0.755) and dominance for pre- (M = 0.573, SD
= 0.217) and post-monsoon (M = 0.598, SD = 0.175); (t (26)
= -0.335, p = 0.741) were also not significantly different. In
pre-monsoon stream MG13 had the highest genera diversity (H’ = 1.63),
however, in post-monsoon MG14 harbored maximum diversity (H’ = 1.62).
Further, genera abundance was also not significantly different between pre- (M
= 24.3, SD = 15.2) and post-monsoon (M = 29.1, SD =
11.4); (t (28) = -0.976, p = 0.330).
Pre-monsoon
correlations between assemblages and environmental factors
Principal Component Analysis (PCA) was
performed between water mite assemblages and environmental factors of
pre-monsoon (Figure 4). Axes with highest percentage of variance and Eigen
values greater than broken-stick Eigen values were considered for the analysis.
Principal axis 1 (57%) and 2 (20%) explained 72% of the total variance.
Temperature (r = 0.821) and salinity (r = 0.511), calcium
hardness (r = 0.405), total hardness (r = 0.470), magnesium
hardness (r = 0.417), electrical conductivity (r = 0.435), and total
dissolved solids (r = 0.430) had strong to moderate positive correlation
with Axis 1. However, chloride (r = -0.617), and ammonia (r =
-0.603) had strong negative correlation with Axis 1. Similarly, Hygrobates (r = -0.755), Lebertia
(r = -0.935), Sperchon (r =
-0.910), Torrenticola (r = -0.730), Woolastookia (r = -0.544) and Monatractides (r = -0.490) exhibited
strong to moderate negative correlation with the first axis.
Ammonia (r = 0.561), turbidity (r = 0.525), chloride (r
= 0.442), and altitude (r = 0.434) had strong to moderate positive
correlation with the second principal axis, whereas magnesium hardness (r
= -0.649), total hardness (r = -0.509), temperature (r = -0.556),
salinity (r = -0.553), total dissolved solids (r = -0.509) and
electrical conductivity (r = -0.464) had strong to moderate negative
correlation. Similarly, Atractides (r =
-0.938) had strong negative correlation with the second axis. However, Lebertia (r = 0.567), Hygrobates
(r = 0.453), Protzia (r =
0.432), and Sperchon (r = 0.499)
exhibited strong to moderate positive correlation with the second principal
axis.
Pearson’s correlation test between environmental factors and water mite
assemblages showed that Atractides (r = 0.572,
p = 0.033) was positively correlated with magnesium hardness. Hygrobates had strong negative correlation with temperature
(r = -0.600, p = 0.023), and salinity (r = -0.574, p
= 0.032). Lebertia was positively correlated with
altitude (r = 0.719, p = 0.004), but negatively correlated with
temperature (r = -0.825, p = 0.002), electrical conductivity (r
= -0.536, p = 0.048), salinity (r = -0.613, p = 0.020) and
total dissolved solids (r = -0.534, p = 0.049). Sperchon was positively correlated with altitude (r
= 0.672, p = 0.009), but negatively correlated with temperature (r
= -0.746, p = 0.002). Torrenticola was
negatively correlated with total hardness (r = -0.621, p = 0.018)
and temperature (r = -0.633, p = 0.015). Woolastookia
was positively correlated with altitude (r = 0.583, p = 0.029)
but negatively correlated with temperature (r = -0.562, p =
0.037).
Post-monsoon
correlations between assemblages and environmental factors
Principal component analysis (PCA) was also performed between
post-monsoon environmental factors and water mite assemblages (Figure 5).
Principal axis 1 (53%) and 2 (24%) explained 77% of the total variability.
Variables such as dissolved oxygen (r = 0.410), temperature (r = 0.445),
electrical conductivity (r = 0.435), salinity (r = 0.456), and
total dissolved solids (r = 0.453) had moderate positive correlation
with first principal axis. Similarly, there was strong to moderate positive
correlation between Monatractides (r =
0.841), Torrenticola (r = -0.552), Aturus (r = -0.333), and Lebertia
(r = -0.327) with the first principal axis. Altitude (r = 0.423),
total hardness (r = 0.496), and calcium hardness (r = 0.496) had
moderate positive correlation with the second axis. Furthermore, Atractides (r = 0.724), Sperchon
(r = 0.667), and Lebertia (r
=0.361) also had strong to moderate positive correlation with principal
axis 1, whereas Monatractides (r =
-0.794) had negative correlation.
Pearson’s correlation test between mites genera abundance and
environmental variables showed that Atractides
had positive correlation with total hardness (r = 0.671, p =
0.006), calcium hardness (r = 0.611, p = 0.015), and electrical
conductivity (r = 0.541, p = 0.037). Sperchonopsis
had strong negative correlation with chloride concentration (r =
-0.545, p = 0.036).
Zoogeographical aspects
All the 15 genera found are predominantly Palearctic in distribution.
The most dominant genera, i.e., Atractides, Lebertia, Monatractides,
Torrenticola and Sperchon
are also dominant genera in Palearctic streams (Di Sabatino
et al. 2008). Oriental genera, such as Nicalimnesia,
Bharatonia, Khedacarus,
Navamamersides, Nilgiriopsis,
Paddelia, and Sinaxonopsis
were not found, also at lower altitudes (~500 m). It must be stated, however, that most of these genera occur in
springs or in the hyporheic, which was not studied during this study. Moreover,
the genus Lebertia is very rare in the
Oriental region (Cook 1967; Di Sabatino et al. 2008).
Discussion
There were no significant differences between
indices of pre- and post-monsoon (p <.05). Further, genera
abundance was also not significantly different (t (28) = -0.976, p =
0.33). This could be due to presence of dominant Palearctic genera and less
observed variation in environmental variables in the two seasons. Similarly, Zawal et al. (2017), Pozojević et
al. (2018), and Zawal et al. (2020) also suggested
that there was no significant variation in seasonal abundance and assemblage of
water mites in lotic habitats of Dinaric region of Croatia and ancient Lake Skadar basin in southern Europe respectively. This could be
anticipated due to high degree microhabitat specialization by most genera (Di Sabatino et al. 2000).
Most water mite genera exhibited negative correlation with water
parameters indicating sensitivity to pollution (Goldschmidt 2016; Savić et al. 2022). Abelho et al. (2021), who carried out an experiment on the effect
of salinity on aquatic macroinvertebrates, also suggested that genera diversity
and abundance are negatively correlated with salinity as it impacts on the
osmoregulation of aquatic insects and often hypertonicity can be lethal
(Griffith 2017). Roberts & Palmeiro (2008), Da Costa et al. (2014), Kent et al.
(2014), and Delaune et al. (2021) suggested that exposure to high
chloride concentration in water causes acute toxicity on macroinvertebrates and
zooplankton. Since most of the mites collected were Palearctic genera, they
exhibited positive correlation with altitude and negative correlation with
temperature. Similarly, Young (1969) and Pozojević et al. (2020) also suggested that Atractides, Lebertia,
Sperchon, and Torrenticola
genera are negatively correlated with temperature and are more abundant at
higher elevations (>1,000 m). High ammonia content in water lowers the
ability to excrete digestive waste for aquatic insects causing toxic built up
in the tissues and the genera abundance declines gradually (Willingham et al.
2016; Wood 2019). Magnesium and chloride ions in the water increase water
hardness, salinity, and electrical conductivity. These ions also contribute to
chloride toxicity modification and cause ameliorating impact on aquatic diversity
(Soucek et al. 2011). Thus, diversity decreases with
increase in water hardness, salinity, chloride, and TDS. During post-monsoon, Atractides (Hygrobatidae)
exhibited a significant positive correlation with water hardness (r =
0.671, p = 0.006) and electrical conductivity (r = 0.541, p
= 0.037). This genus was relatively abundant in hard water with higher
electrical conductivity habitats. However, it should not be interpreted as
affinity towards polluted environments but rather as higher tolerance against
unfavorable conditions. Similarly, Goldschmidt (2016) indicated that genera
from the family Hygrobatidae are relatively abundant
in polluted environments, indicating a higher tolerance for pollutants.
The 15 streams were grouped in three altitudinal ranges, namely between
500–1,000 m (low), 1,001–1,999 m (mid) and above 2000 m (high) (Table 5, Figure
6). The abundance of water mites increased in higher altitudes. Some of the
genera seem to show a preference for either lower or higher altitudinal ranges
with Woolastookia being restricted to higher
altitude, Lebertia preferring higher altitudes
and Monatractides being largely absent at
higher altitude. All 15 genera collected had a largely Palearctic distribution,
and typical Oriental genera such as Nicalimnesia,
Bharatonia, Khedacarus,
Navamamersides, Nilgiriopsis,
Paddelia, and Sinaxonopsis
were not encountered. In general, the Bhutanese fauna below 1,000 m becomes
increasingly dominated by Oriental genera (Rasaily et
al. 2021), hence the absence of Oriental water mite taxa is surprising. It
seems likely that the fast-flowing water bodies in which our sampling took
place allows the Palearctic genera to occur at lower altitude and prevents the
occurrence of Oriental genera. Furthermore, most mites we sampled were stream
dwelling, unlike oriental genera which are more abundant in spring and standing
water habitats (Pešić et al. 2012). Sampling of
standing waters at lower altitude or smaller brooks fed by local sources will
probably show that such habitats are at least inhabited and may be even
dominated by Oriental genera. Although there is an increasing abundance of
mites along the altitudinal gradient, there is no change in genera diversity.
There was a uniform faunal composition throughout the altitude dominated by
Palearctic genera.
Ethical
standards
The research project with permit no. 17703966556045F2C2BFD63 was
approved by Ugyen Wangchuck
Institute for Conservation and Environmental Research (UWICER), Lamaigoenpa, Bumthang Bhutan.
Specimen collections and preservation were done following standard protocols as
detailed in the methods section.
Table 1. Summary of environmental
characterization of pre- and post-monsoon, 2021.
ID |
Season |
Alt |
NH4 |
Ca. H |
Cl |
E.C |
DO |
Mg. H |
pH |
Sal |
TDS |
Tem |
TH |
Tur |
MG 1 |
Pre- |
516±38.4 |
0.02±0.002 |
71.02±6.36 |
90.9±6.75 |
112.8±2.49 |
15.95±0.9 |
15.2±7.49 |
6.72±1.81 |
39.2±0.61 |
79.9±1.60 |
19.4±0.38 |
86.2±8.53 |
0.85±0.24 |
Post- |
516±38.42 |
1.38±0.08 |
13.1±0.85 |
20.6±7.56 |
71.2±1.25 |
10.55±0.20 |
24.7±5.12 |
7.87±0.22 |
43.7±6.48 |
35.7±5.29 |
17.9±0.33 |
37.8±5.97 |
0.40±0.24 |
|
MG 2 |
Pre- |
613±21.4 |
0.03±0.01 |
56.2±5.02 |
93.05±12.4 |
207.2±2.06 |
10.7±0.64 |
18.9±4.35 |
8.14±0.04 |
57.3±12.4 |
104.2±41.6 |
22.9±0.20 |
75.2±9.32 |
0.80±0.12 |
Post- |
613±21.4 |
1.81±0.08 |
38.5±3.41 |
50.1±3.02 |
116.8±0.85 |
9.32±0.17 |
8.25±1.70 |
8.14±0.04 |
52.8±0.85 |
46.3±0.46 |
21.9±0.64 |
46.7±5.12 |
0.68±0.18 |
|
MG 3 |
Pre- |
662±78.4 |
0.04±0.01 |
35.2±4.87 |
88.9±7.91 |
148.2±5.21 |
11.4±0.83 |
12.02±5.35 |
7.04±0.09 |
48.9±0.26 |
102.6±0.47 |
20.4±1.05 |
47.2±8.18 |
0.81±0.30 |
Post- |
662±78.4 |
1.66±0.12 |
32.5±3.41 |
33.4±1.51 |
103.5±0.42 |
8.46±0.12 |
14±3.07 |
7.21±0.08 |
50.7±0.25 |
44.6±0.64 |
22.4±0.08 |
46.5±3.41 |
0.50±0.30 |
|
MG 4 |
Pre- |
575±46.4 |
0.03±0.005 |
54.05±7.4 |
103.3±19.6 |
80.1±0.71 |
10.1±1.05 |
20.5±5.90 |
7.51±0.10 |
30.2±0.08 |
57.06±0.61 |
19.9±0.12 |
74.6±6.42 |
1.22±0.25 |
Post- |
575±46.4 |
0.98±0.08 |
12.8±0.85 |
18.3±7.56 |
46.6±1.28 |
10.3±0.25 |
13±6.83 |
8.06±0.12 |
23.2±0.08 |
20.1±0.12 |
21.2±0.34 |
25.8±7.68 |
0.19±0.08 |
|
MG 5 |
Pre- |
565±36.6 |
0.03±0.002 |
28.2±6.39 |
93.05±15.6 |
83.5±4.95 |
9.01±0.94 |
15.5±6.55 |
7.47±0.008 |
30.9±1.57 |
59.5±3.77 |
19.4±0.12 |
43.7±9.46 |
0.97±0.17 |
Post- |
565±36.6 |
1.4±0.20 |
18.2±0.49 |
44.1±1.51 |
38.2±0.5 |
7.88±0.21 |
13.5±3.41 |
7.66±0.22 |
18.7±0.54 |
16.3±0.40 |
17.8±0.21 |
31.5±3.41 |
0.19±0.06 |
|
MG 6 |
Pre- |
1103±49.9 |
0.04±0.002 |
40.1±5.12 |
128.2±19.6 |
48.8±0.43 |
15.7±0.66 |
30.2±6.49 |
7.67±0.05 |
19.3±0.14 |
34.6±0.16 |
14.6±0.54 |
70.3±11.05 |
0.62±0.20 |
Post- |
1103±49.9 |
1.21±0.13 |
18.6±2.56 |
42.1±3.02 |
35.1±0.85 |
7.781±0.08 |
7.12±0.85 |
7.51±0.08 |
12.5±0.18 |
10.9±0.16 |
12.6±0.12 |
25.7±1.70 |
0.75±0.13 |
|
MG 7 |
Pre- |
1118±102.4 |
0.04±0.009 |
44±4.54 |
130.2±19.5 |
215±0.81 |
14.01±0.77 |
16±8.28 |
7.15±0.012 |
72.3±3.58 |
153.3±1.24 |
18.3±0.26 |
60±12.7 |
0.40±0.06 |
Post- |
1118±102.4 |
1.25±0.12 |
19.3±2.56 |
118.5±1.51 |
59.4±0.42 |
7.93±0.12 |
22.7±0.95 |
7.58±0.08 |
28.8±0.25 |
24.9±0.12 |
18.6±0.17 |
41.3±2.56 |
0.80±0.08 |
|
MG 8 |
Pre- |
1246±43.3 |
0.03±0.01 |
59±2.16 |
136.4±14.3 |
85.4±2.18 |
11.7±1.46 |
14.5±4.79 |
7.48±0.01 |
30.03±0.55 |
60.8±1.32 |
15.1±0.40 |
73.5±5.19 |
0.42±0.07 |
Post- |
1246±43.3 |
0.61±0.08 |
12.8±0.85 |
50.07±3.02 |
38.8±0.85 |
7.55±0.33 |
9.75±1.70 |
7.7±0.34 |
19.3±0.14 |
16.8±0.05 |
14.7±0.08 |
22.6±2.56 |
0.66±0.10 |
|
MG 9 |
Pre- |
1470±76.4 |
0.04±0.009 |
50±5.22 |
128.2±4.77 |
151.6±4.90 |
13.6±0.77 |
11.5±2.38 |
7.65±0.08 |
49.5±1.34 |
108±2.94 |
14.8±0.35 |
61.5±7.54 |
0.37±0.03 |
Post- |
1470±76.4 |
0.36±0.09 |
45.3±24.7 |
54.2±4.54 |
69.4±0.42 |
8.55±0.34 |
15.8±7.68 |
8.075±0.17 |
32.7±0.59 |
28.1±0.55 |
15.3±0.25 |
61.2±32.4 |
0.84±0.16 |
|
MG 10 |
Pre- |
1131±169.6 |
0.03±0.006 |
49±6.17 |
113.7±7.91 |
353±0.81 |
12.6±1.04 |
79.7±6.35 |
8.07±0.12 |
112.6±0.47 |
250.6±0.94 |
17.4±0.29 |
128.7±6.22 |
0.29±0.02 |
Post- |
1131±169.6 |
0.50±0.13 |
97.1±0.85 |
77.1±18.1 |
209.4±0.42 |
11.3±0.08 |
23.7±11.9 |
8.66±0.22 |
103.9±0.59 |
90.9±1.11 |
16.6±0.21 |
120.8±12.8 |
0.35±0.12 |
|
MG 11 |
Pre- |
1163±212.8 |
0.04±0.003 |
54.6±1.20 |
150.9±29.7 |
160.9±0.63 |
14.9±1.33 |
17.7±3.57 |
8.31±0.19 |
52.6±0.16 |
114.6±0.47 |
15.4±0.12 |
72.4±3.57 |
1.10±0.01 |
Post- |
1163±212.8 |
0.61±0.08 |
35±6.83 |
72.8±1.51 |
89.25±0.5 |
9.32±0.17 |
14.7±5.12 |
7.89±0.08 |
44.2±0.12 |
38.3±0.17 |
16.1±0.08 |
49.7±1.70 |
0.34±0.107 |
|
MG 12 |
Pre- |
2606±5.5 |
0.04±0.001 |
63.9±1.57 |
167.5±27.3 |
231.1±44.4 |
13.8±0.81 |
14.7±3.33 |
7.77±0.28 |
66.3±9.21 |
158±22.6 |
7.66±0.24 |
78.6±2.72 |
1.57±0.02 |
Post- |
2606±5.5 |
0.6±0.14 |
48.5±3.4 |
45.1±6.05 |
126.2±1.70 |
6.68±0.21 |
21.5±3.41 |
8.64±0.17 |
61.2±0.34 |
53.4±0.59 |
12.5±0.38 |
70.5±1 |
0.82±0.06 |
|
MG 13 |
Pre- |
2588±15.5 |
0.04±0.002 |
47.2±2.62 |
148.8±13.5 |
133.5±12.1 |
14.4±0.78 |
8.72±3.37 |
8.35±0.02 |
40.2±0.89 |
88.8±2.46 |
11.4±0.21 |
56±0.99 |
0.76±0.06 |
Post- |
3271±31.1 |
0.21±0.32 |
31.7±1.70 |
54.5±9.08 |
46.3±9.39 |
6.71±0.08 |
39.3±2.56 |
7.77±0.51 |
23.1±4.39 |
20.05±3.65 |
13.36±0.42 |
71.1±0.85 |
0.58±0.17 |
|
MG 14 |
Pre- |
2588±49.3 |
0.05±0.01 |
38.2±6.23 |
148.8±20.2 |
43.2±2.05 |
10.1±0.76 |
10.6±1.66 |
7.73±0.07 |
14.3±0.571 |
30.7±1.38 |
7.56±0.16 |
48.9±7.62 |
1.12±0.08 |
Post- |
2588±49.3 |
0.18±0.08 |
17.6±9.39 |
67.7±3.02 |
21.4±0.42 |
8.31±0.76 |
23.5±10.2 |
8.01±0.13 |
9.76±0.09 |
8.44±0.05 |
13.2±0.25 |
41.1±0.85 |
0.70±0.10 |
|
MG 15 |
Pre- |
2494±26.1 |
0.05±0.006 |
35.3±1.26 |
173.7±30.2 |
62.6±0.91 |
12.2±0.60 |
9.50±0.71 |
7.57±0.04 |
19.9±0.32 |
44.6±0.62 |
7.93±0.18 |
44.8±1.08 |
0.89±0.03 |
Post- |
2494±26.1 |
0.24±0.23 |
44.3±4.26 |
45.6±3.02 |
30.8±4.69 |
7.73±0.18 |
2.87±0.85 |
8.11±0.21 |
12.2±0.49 |
10.5±0.19 |
13.4±0.25 |
47.2±5.12 |
0.48±0.11 |
Alt—Altitude | NH4—Ammonia
| Ca. H—Calcium hardness | Cl—Chloride | EC—Electrical conductivity |
D.O—Dissolved Oxygen | Mg. H—Magnesium hardness | Sal—Salinity | TDS—Total
dissolved solid | Tem—Temperature | TH—Total Hardness
| Tur—Turbidity.
Table 2. Pre- and post-monsoon mite abundance
at different elevations.
|
Genus |
Season |
500–1000 m |
1,001–1,999 m |
>2,000 m |
||||||||||||
MG 1 |
MG 2 |
MG 3 |
MG 4 |
MG 5 |
MG 6 |
MG 7 |
MG 8 |
MG 9 |
MG 10 |
MG 11 |
MG 12 |
MG 13 |
MG 14 |
MG 15 |
|||
1 |
Atractides |
Pre |
12 |
2 |
2 |
3 |
10 |
0 |
14 |
2 |
5 |
15 |
0 |
3 |
2 |
0 |
2 |
Post |
1 |
4 |
16 |
1 |
4 |
0 |
5 |
1 |
0 |
23 |
0 |
12 |
6 |
9 |
6 |
||
2 |
Aturus |
Post |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
3 |
Hygrobates |
Pre |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
3 |
Post |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
||
4 |
Kongsbergia |
Post |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
5 |
Lebertia |
Pre |
1 |
0 |
0 |
0 |
0 |
0 |
3 |
0 |
1 |
0 |
0 |
5 |
12 |
17 |
20 |
Post |
0 |
0 |
0 |
0 |
4 |
0 |
1 |
0 |
0 |
0 |
0 |
2 |
2 |
3 |
0 |
||
6 |
Limnesia |
Post |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
7 |
Monatractides |
Pre |
3 |
3 |
15 |
3 |
1 |
0 |
0 |
0 |
5 |
1 |
9 |
2 |
2 |
1 |
1 |
Post |
19 |
5 |
16 |
12 |
4 |
8 |
33 |
12 |
23 |
12 |
17 |
0 |
0 |
1 |
0 |
||
8 |
Piona |
Post |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
9 |
Protzia |
Pre |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
Post |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
2 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
||
10 |
Pseudotorrenticola |
Post |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
11 |
Sperchon |
Pre |
2 |
4 |
0 |
2 |
3 |
0 |
0 |
0 |
3 |
4 |
0 |
5 |
11 |
11 |
13 |
Post |
2 |
13 |
5 |
1 |
2 |
0 |
0 |
0 |
0 |
6 |
0 |
2 |
3 |
10 |
7 |
||
12 |
Sperchonopsis |
Pre |
1 |
2 |
1 |
0 |
0 |
0 |
0 |
0 |
3 |
0 |
0 |
2 |
0 |
0 |
0 |
Post |
5 |
2 |
4 |
1 |
0 |
0 |
0 |
3 |
1 |
0 |
0 |
4 |
0 |
2 |
0 |
||
13 |
Testudacarus |
Post |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
14 |
Torrenticola |
Pre |
0 |
3 |
9 |
4 |
14 |
0 |
9 |
3 |
10 |
2 |
1 |
18 |
9 |
10 |
17 |
Post |
7 |
8 |
3 |
13 |
0 |
0 |
0 |
14 |
8 |
0 |
2 |
17 |
2 |
11 |
3 |
||
15 |
Woolastookia |
Pre |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
2 |
3 |
0 |
1 |
Total |
|
19/34 |
14/33 |
27/44 |
12/30 |
28/14 |
0/8 |
26/39 |
5/33 |
27/34 |
22/42 |
10/20 |
37/37 |
40/15 |
41/38 |
47/16 |
Table 3. Summary of water mites genera
diversity indices of two seasons in 15 streams. SR—genera richness | E—evenness
| H’—Shannon diversity index | D—dominance of (1) pre- and (2)
post-monsoon.
Streams |
Pre-monsoon |
Post-monsoon |
||||||
SR1 |
E1 |
H1 |
D1 |
SR2 |
E2 |
H2 |
D2 |
|
MG1 |
5 |
0.70 |
1.13 |
0.56 |
5 |
0.75 |
1.20 |
0.62 |
MG2 |
5 |
0.98 |
1.57 |
0.79 |
5 |
0.89 |
1.44 |
0.73 |
MG3 |
4 |
0.73 |
1.00 |
0.57 |
5 |
0.86 |
1.38 |
0.71 |
MG4 |
4 |
0.98 |
1.35 |
0.74 |
6 |
0.66 |
1.19 |
0.62 |
MG5 |
4 |
0.77 |
1.07 |
0.61 |
4 |
0.98 |
1.35 |
0.73 |
MG6 |
- |
- |
- |
- |
1 |
0 |
0 |
0 |
MG7 |
3 |
0.86 |
0.95 |
0.58 |
3 |
0.45 |
0.50 |
0.27 |
MG8 |
2 |
0.97 |
0.67 |
0.48 |
6 |
0.74 |
1.33 |
0.67 |
MG9 |
6 |
0.90 |
1.60 |
0.77 |
4 |
0.58 |
0.81 |
0.45 |
MG10 |
4 |
0.67 |
0.93 |
0.49 |
4 |
0.76 |
1.06 |
0.60 |
MG11 |
2 |
0.47 |
0.33 |
0.18 |
2 |
0.49 |
0.34 |
0.19 |
MG12 |
7 |
0.81 |
1.57 |
0.07 |
5 |
0.79 |
1.28 |
0.67 |
MG13 |
7 |
0.84 |
1.63 |
0.77 |
5 |
0.89 |
1.44 |
0.72 |
MG14 |
6 |
0.77 |
1.33 |
0.69 |
7 |
0.83 |
1.62 |
0.77 |
MG15 |
7 |
0.76 |
1.48 |
0.73 |
3 |
0.95 |
1.04 |
0.63 |
Average |
4.4±2.06 |
0.75±0.25 |
1.11±0.48 |
0.53±0.26 |
4.33±1.60 |
0.71±0.25 |
1.06±0.46 |
0.56±0.23 |
Table 4. Correlation between pre- and
post-monsoon mean diversity indices.
|
SR2 |
E2 |
H’2 |
D2 |
SR1 |
.479 |
.719** |
.642** |
.680** |
E1 |
.726** |
.704** |
.709** |
.725** |
H’1 |
.587* |
.713** |
.693** |
.724** |
D1 |
.515* |
.609* |
.580* |
.605* |
Correlation is
significant at the 0.05 level (2-tailed). **—Correlation is significant at
the 0.01 level (2-tailed) | SR—genera richness | E—evenness
| H’—Shannon diversity index | D—dominance of (1)
pre-monsoon and (2) post-monsoon (2). |
For figures &
images - - click here for full PDF
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