Chironomid larvae (Diptera, Chironomidae) are an important ecosystem component in various inland waters and marine lagoons, as they play a key role in their production processes and nutrient dynamics as well as in matter and energy exchange between aquatic and terrestrial ecosystems (Balushkina 1987; Armitage et al. 1995; Muehlbauer et al. 2014; Shadrin et al. 2017). For example, they provide the main phosphorus flux from bottom sediments into the water column (Biswas et al. 2009). Being an important component in the diet of many fish species, they determine fish productivity in water bodies (Balushkina 1987; Armitage et al. 1995). Quantitative assessment of the functional role of chironomid larvae is an important issue in the ecology of inland waters and lagoons.
Animal body mass is an important functional indicator that determines the intensity of metabolism, growth and other processes (Menzie 1981; Balushkina 1987). Knowledge of animal mass values and patterns of variation in populations of different organisms is a necessary prerequisite for understanding the functional role of populations in ecosystems. It is often easier and faster to measure linear characteristics of chironomid larvae than the mass of their bodies (Balushkina 1987; Miyasaka et al. 2008). It has been established that the relationship between the mass of larvae and their linear characteristics (length and width of the head capsule) is well approximated by parabolic equations (Balushkina 1987; Miyasaka et al. 2008):
where W – body mass, mg; L – body length/width of the head capsule, mm; a, b – coefficients.
Often the task is to calculate the body mass of chironomids retrieved from the stomachs of fish. Chitinized parts of the body are best preserved in the stomachs of fish, head capsules in particular, the width of which can be used to determine the length and mass of the consumed chironomid larvae. In the literature, generalized equations for mass relationships with linear characteristics of chironomid larvae are provided (Toderash 1984; Balushkina 1987; Miyasaka et al. 2008). However, the relationships between the body length, body mass and width of the head capsule in larvae vary in different water bodies (Balushkina 1987; Kravtsova 2007; Shadrin et al. 2017; Schütz & Füreder 2018). The exponent “b” in equation (1) describing the relationship between the body mass and the length of chironomid larvae according to values of this parameter available in the literature varies over a wide range:
In the Crimea region, which is the largest Black Sea peninsula with an area of 27000 km2, there are many water bodies with varying salinity – from freshwater to hypersaline (Anufriieva et al. 2014; Anufriieva & Shadrin 2014a; Shadrin et al. 2017). Chironomid larvae reach high abundance in these water bodies, play an important functional role and are considered a valuable biological resource (Balushkina et al. 2009; Shadrin et al. 2017). Chironomid larvae inhabit water bodies characterized by a wide range of salinity, up to 270–280 PSU, and
The purpose of the study was to determine the width of the head capsule, the length and body mass of larvae of
In Crimea, natural water bodies are predominantly saline/hypersaline. Their distribution is shown in Figure 1. There are more than 50 relatively large and many smaller hypersaline water bodies, including Sivash Bay (the Sea of Azov), which is the largest (2560 km2) hypersaline lagoon in the world (Balushkina et al. 2009; Shadrin & Anufriieva 2013; Anufriieva et al. 2014; Shadrin et al. 2017; Shadrin et al. 2018). Based on their origin and ionic composition, Crimean saline natural water bodies are divided into marine (thalassohaline) and continental (athalassohaline-sulfate) ones. All Crimean saline lakes are shallow and polymictic with a wide range of abiotic factors (temperature, salinity, pH, etc.) and are characterized by a varied biotic composition. In 2000–2016, the biotic composition and ecology of Crimean water bodies were studied and the results were partially published (Balushkina et al. 2009; Belmonte et al. 2012; Shadrin & Anufriieva 2013; Anufriieva et al. 2014). To analyze the size and mass of chironomid larvae in 55 samples of benthos, filamentous green algae mats and plankton collected in 2012–2016 were used. Collection methods described in the literature were used (Balushkina et al. 2009; Shadrin & Anufriieva 2013; Anufriieva et al. 2014; Shadrin et al. 2017; 2018; Anufriieva et al. 2018). Chironomid larvae are not known to be planktic dwellers but in hypersaline waters many of the typically benthic animals, including chironomid larvae, live in the water column or in floating filamentous green algae
For samples (Table 1) where 10 or more larvae of a size range more than 2 mm (see Tables 2–4) were measured, and parameters of the regression equations were calculated:
Crimean water bodies where samples were collected to measure chironomid larvae traits
Lake, date | Coordinates | Salinity, PSU | Temperature,°C | pH |
---|---|---|---|---|
Pond near the village of Chelyadinovo, 05.08.2012 | 45°12ʹ28ʹʹN; 36°21ʹ47ʹʹE | 24 | 32 | 7.55 |
Lake Yanyshskoye, 05.08.2012 | 45°07ʹ57ʹʹN; 36°25ʹ25ʹʹE | 166 | 36 | 8.01 |
Lake Dzharylhatch, 09.08.2012 | 45°33ʹ53ʹʹN; 32°51ʹ47ʹʹE | 145 | 26 | 6.67 |
Lake Bolshoi Kipchak, 09.08.2012 | 45°22ʹ06ʹʹN; 32°31ʹ06ʹʹE | 280 | 27 | 6.85 |
Lake Chersonesskoye, 23.05.2013 | 44°35ʹ10ʹʹN; 33°23ʹ33ʹʹE | 43 | 28 | – |
Lake Aktashskoye, 05.08.2013 | 45°23ʹ35ʹʹN; 35°48ʹ18ʹʹE | 130 | 29 | 8.77 |
Lake Aktashskoye, 05.08.2013 | 45°21ʹ05ʹʹN; 35°48ʹ39ʹʹE | 40 | 28 | 8.55 |
Lake Aktashskoye, 05.08.2013 | 45°23ʹ17ʹʹN; 35°48ʹ16ʹʹE | 220 | 17 | – |
Pond in the Kamysh-Burun iron ore quarry, 06.08.2013 | 45°16ʹ40ʹʹN; 36°23ʹ23ʹʹE | 0 | 30 | – |
Pond near the village of Erofeevo, 08.08.2013 | 45°12ʹ05ʹʹN; 35°39ʹ01ʹʹE | 9 | 28 | 9.71 |
Pond near Lake Kiyatskoye, 08.08.2013 | 45°58ʹ53ʹʹN; 33°57ʹ56ʹʹE | 10 | 31 | 8.60 |
Lake Bolshoi Kipchak, 09.08.2013 | 45°22ʹ06ʹʹN; 32°31ʹ06ʹʹE | 145 | 34 | 7.72 |
Lake Kiyatskoye, 01.10.2014 | 59ʹ48.01ʹʹN; 33°57ʹ11ʹʹE | 180 | 15 | – |
Lake Dzharylhatch, 05.10.2014 | 45°33ʹ53ʹʹN; 32°51ʹ47ʹʹE | 106 | 16 | – |
Lake Chersonesskoye, 12.07.2015 | 44°35ʹ10ʹʹN; 33°23ʹ33ʹʹE | 122 | 24 | – |
Sivash Bay, 11.08.2015 | 45°31ʹ39ʹʹN; 35°10ʹ41ʹʹE | 65 | 30 | – |
Lake Kiyatskoye, 15.08.2015 | 59ʹ48.01ʹʹN; 33°57ʹ11ʹʹE | 185 | 27 | – |
Lake Kiyatskoye, 14.06.2016 | 59ʹ48.01ʹʹN; 33°57ʹ11ʹʹE | 190 | 30 | 7.70 |
Lake Kuchuk-Adzhigol, 07.07.2016 | 45°06ʹ03ʹʹN; 35°27ʹ02 ʹʹE | 10 | 23 | 9.50 |
Lake Sakskoye, 28.07.2016 | 45°07ʹ32ʹʹN; 33°35ʹ36ʹʹE | 200 | 29 | – |
Coefficients of equation (2) describing the “body length–head capsule width” relationship for chironomid larvae from different Crimean water bodies
Lake, date | Salinity, PSU | Length range, mm | Head capsule width range, mm | n | Coefficients of equation 2 | С7, mm | R | |
---|---|---|---|---|---|---|---|---|
k | m | |||||||
Pond near the village of Chelyadinovo, 05.08.2012 | 24 | 2.0–5.7 | 0.105–0.238 | 28 | 0.056 | 0.862 | 0.300 | 0.913 |
Lake Yanyshskoye, 05.08.2012 | 166 | 3.0–8.5 | 0.11–0.342 | 39 | 0.037 | 1.010 | 0.264 | 0.935 |
Lake Bolshoi Kipchak, 09.08.2012 | 280 | 3.0–9.0 | 0.133–0.300 | 65 | 0.057 | 0.752 | 0.245 | 0.992 |
Lake Chersonesskoye, 23.05.2013 | 43 | 1.3–3.5 | 0.120–0.231 | 15 | 0.070 | 0.851 | 0.367 | 0.584 |
Lake Aktashskoye, 05.08.2013 | 130 | 2.0–9.0 | 0.074–0.311 | 70 | 0.052 | 0.834 | 0.264 | 0.920 |
Lake Aktashskoye, 05.08.2013 | 40 | 1.5–12.0 | 0.067–0.308 | 41 | 0.055 | 0.705 | 0.217 | 0.987 |
Lake Aktashskoye, 05.08.2013 | 220 | 2.0–8.0 | 0.105–0.295 | 159 | 0.062 | 0.702 | 0.243 | 0.973 |
Lake Bolshoi Kipchak, 09.08.2013 | 145 | 2.5–9.0 | 0.107–0.342 | 25 | 0.047 | 0.902 | 0.272 | 0.960 |
Lake Kiyatskoye, 01.10.2014 | 180 | 3.5–7.5 | 0.118–0.276 | 101 | 0.031 | 1.123 | 0.276 | 0.968 |
Lake Dzharylhatch, 05.10.2014 | 106 | 2.0–9.0 | 0.081–0.321 | 50 | 0.040 | 0.961 | 0.259 | 0.992 |
Lake Chersonesskoye, 12.07.2015 | 122 | 2.0–10.0 | 0.074–0.355 | 25 | 0.052 | 0.837 | 0.265 | 0.873 |
Sivash Bay, 11.08.2015 | 65 | 0.8–6.0 | 0.071–0.213 | 11 | 0.082 | 0.500 | 0.217 | 0.927 |
Lake Kiyatskoye, 15.08.2015 | 185 | 2.0–7.5 | 0.089–0.271 | 178 | 0.045 | 0.886 | 0.252 | 0.973 |
Lake Kiyatskoye, 14.06.2016 | 190 | 1.5–8.0 | 0.084–0.289 | 64 | 0.060 | 0.726 | 0.246 | 0.960 |
Lake Sakskoye, 28.07.2016 | 200 | 2.3–7.5 | 0.232–0.574 | 26 | 0.133 | 0.721 | 0.541 | 0.928 |
Pond near the village of Erofeevo, 08.08.2013 | 9 | 2.2–5.5 | 0.141–0.284 | 17 | 0.126 | 0.496 | 0.331 | 0.749 |
Pond near Lake Kiyatskoye, 08.08.2013 | 10 | 1.5–4.7 | 0.242–0.529 | 10 | 0.193 | 0.656 | 0.692 | 0.983 |
Lake Kuchuk-Adzhigol, 07.07.2016 | 10 | 2.3–6.5 | 0.105–0.269 | 38 | 0.072 | 0.636 | 0.248 | 0.869 |
Pond in the Kamysh-Burun iron ore quarry, 06.08.2013 | 0 | 1.6–3.7 | 0.09–0.144 | 12 | 0.078 | 0.479 | 0.198 | 0.752 |
Lake Kuchuk-Adzhigol, 07.07.2016 | 10 | 2.3–5.5 | 0.103–0.194 | 136 | 0.070 | 0.621 | 0.247 | 0.859 |
n– number of measured larvae; k, m – coefficients of equation (2); C7 – calculated width of the head capsule in 7 mm long larvae; R – coefficient of correlation.
Coefficients of equation (3) “length–mass” for chironomid larvae from different Crimean water bodies
Lake, date | Salinity, PSU | Length range, mm | Mass, mg | n | Coefficients of equation 3 | W7 | R | |
---|---|---|---|---|---|---|---|---|
a | b | |||||||
Pond near the village of Chelyadinovo, 05.08.2012 | 24 | 2.0–5.7 | 0.10–3.50 | 28 | 0.014 | 2.357 | 1.374 | 0.952 |
Lake Yanyshskoye, 05.08.2012 | 166 | 3.0–8.5 | 0.20–2.00 | 39 | 0.051 | 1.702 | 0.384 | 0.972 |
Lake Dzharylhatch, 09.08.2012 | 145 | 2.0–7.0 | 0.07–2.80 | 35 | 0.008 | 2.570 | 1.188 | 0.993 |
Lake Bolshoi Kipchak, 09.08.2012 | 280 | 3.0–9.0 | 0.12–1.83 | 65 | 0.007 | 2.570 | 1.040 | 0.994 |
Lake Chersonesskoye, 23.05.2013 | 43 | 1.3–3.5 | 0.04–0.40 | 13 | 0.021 | 2.376 | 2.139 | 0.951 |
Lake Aktashskoye, 05.08.2013 | 130 | 2.0–9.0 | 0.05–3.00 | 70 | 0.007 | 2.707 | 1.358 | 0.995 |
Lake Aktashskoye, 05.08.2013 | 40 | 1.5–12.0 | 0.03–4.00 | 41 | 0.009 | 2.518 | 1.208 | 0.976 |
Lake Aktashskoye, 05.08.2013 | 220 | 2.0–8.0 | 0.07–1.50 | 159 | 0.015 | 2.064 | 0.832 | 0.972 |
Lake Bolshoi Kipchak, 09.08.2013 | 145 | 2.5–9.0 | 0.07–2.60 | 25 | 0.003 | 3.057 | 1.150 | 0.974 |
Lake Kiyatskoye, 01.10.2014 | 180 | 3.5–7.5 | 0.20–1.30 | 101 | 0.008 | 2.595 | 1.248 | 0.971 |
Lake Dzharylhatch, 05.10.2014 | 106 | 2.0–9.0 | 0.06–1.80 | 50 | 0.008 | 2.351 | 0.776 | 0.978 |
Lake Chersonesskoye, 12.07.2015 | 122 | 2.0–10.0 | 0.20–3.50 | 25 | 0.053 | 1.693 | 1.429 | 0.966 |
Sivash Bay, 11.08.2015 | 65 | 0.8–6.0 | 0.07–2.80 | 11 | 0.064 | 1.556 | 1.322 | 0.998 |
Lake Kiyatskoye, 15.08.2015 | 185 | 2.0–7.5 | 0.04–0.95 | 178 | 0.007 | 2.427 | 0.787 | 0.995 |
Lake Kiyatskoye, 14.06.2016 | 190 | 1.5–8.0 | 0.08–1.00 | 64 | 0.035 | 1.425 | 0.560 | 0.936 |
Lake Sakskoye, 28.07.2016 | 200 | 2.3–7.5 | 0.10–1.20 | 26 | 0.036 | 1.425 | 0.576 | 0.923 |
Pond near the village of Erofeevo, 08.08.2013 | 9 | 2.2–5.5 | 0.25–1.00 | 17 | 0.039 | 1.943 | 1.710 | 0.890 |
Pond near Lake Kiyatskoye, 08.08.2013 | 10 | 1.5–4.7 | 0.05–0.80 | 10 | 0.018 | 2.438 | 2.068 | 0.997 |
Lake Kuchuk-Adzhigol, 07.07.2016 | 10 | 2.3–6.5 | 0.125–2.00 | 38 | 0.012 | 2.592 | 1.861 | 0.969 |
Pond in the Kamysh-Burun iron ore quarry, 06.08.2013 | 0 | 1.6–3.7 | 0.10–0.50 | 12 | 0.026 | 2.067 | 1.451 | 0.879 |
Lake Kuchuk-Adzhigol, 07.07.2016 | 10 | 2.3–5.5 | 0.13–0.84 | 136 | 0.023 | 1.859 | 0.857 | 0.918 |
n– number of measured larvae; a, b – coefficients of equation (3); W7 – calculated mass of 7 mm long larvae; R – coefficient of correlation
Coefficients of equation (4) describing the “head capsule width–mass” relationship for chironomid larvae from different Crimean water bodies
Lake, date | Salinity, PSU | Head capsule width range, mm | Mass, mg | n | Coefficients of equation 4 | W0.250, mg | R | |
---|---|---|---|---|---|---|---|---|
c | d | |||||||
Pond near the village of Chelyadinovo, 05.08.2012 | 24 | 0.105–0.238 | 0.10–3.50 | 28 | 6.597 | 1.833 | 0.521 | 0.682 |
Lake Yanyshskoye, 05.08.2012 | 166 | 0.11–0.342 | 0.20–2.00 | 39 | 12.032 | 1.788 | 1.022 | 0.724 |
Lake Dzharylhatch, 09.08.2012 | 145 | 0.07–0.282 | 0.07–2.80 | 35 | 21.923 | 2.32 | 0.887 | 0.988 |
Lake Bolshoi Kipchak, 09.08.2012 | 280 | 0.133–0.300 | 0.12–1.83 | 65 | 113.630 | 3.378 | 1.023 | 0.994 |
Lake Chersonesskoye, 23.05.2013 | 43 | 0.076–0.381 | 0.04–0.40 | 15 | 1.203 | 1.182 | 0.233 | 0.738 |
Lake Aktashskoye, 05.08.2013 | 130 | 0.074–0.311 | 0.05–3.00 | 70 | 45.275 | 2.769 | 0.973 | 0.909 |
Lake Aktashskoye, 05.08.2013 | 40 | 0.067–0.306 | 0.03–4.00 | 41 | 281.190 | 3.557 | 2.025 | 0.984 |
Lake Aktashskoye, 05.08.2013 | 220 | 0.105–0.295 | 0.07–1.50 | 159 | 55.700 | 2.941 | 0.947 | 0.999 |
Lake Bolshoi Kipchak, 09.08.2013 | 145 | 0.107–0.342 | 0.07–2.60 | 25 | 89.186 | 3.311 | 0.901 | 0.960 |
Lake Dzharylhatch, 05.10.2014 | 106 | 0.08–0.320 | 0.06–1.80 | 50 | 21.001 | 2.443 | 0.714 | 0.983 |
Lake Chersonesskoye, 12.07.2015 | 122 | 0.074–0.355 | 0.20–3.50 | 25 | 7.079 | 1.425 | 0.984 | 0.807 |
Sivash Bay, 11.08.2015 | 65 | 0.07–0.215 | 0.05–1.00 | 11 | 77.266 | 2.752 | 1.700 | 0.926 |
Lake Kiyatskoye, 15.08.2015 | 185 | 0.09–0.271 | 0.04–0.95 | 178 | 30.982 | 2.648 | 0.790 | 0.989 |
Lake Kiyatskoye, 14.06.2016 | 190 | 0.08–0.289 | 0.08–1.00 | 64 | 4.178 | 1.571 | 0.472 | 0.845 |
Lake Sakskoye, 28.07.2016 | 200 | 0.232–0.61 | 0.10–1.20 | 28 | 3.344 | 1.853 | 0.257 | 0.799 |
Pond near the village of Erofeevo, 08.08.2013 | 9 | 0.139–0.291 | 0.14–0.28 | 17 | 3.955 | 1.389 | 0.577 | 0.559 |
Pond near Lake Kiyatskoye, 08.08.2013 | 10 | 0.242–0.529 | 0.05–0.80 | 10 | 7.173 | 3.578 | 0.052 | 0.978 |
Lake Kuchuk-Adzhigol, 07.07.2016 | 10 | 0.105–0.269 | 0.11–0.27 | 38 | 124.62 | 3.277 | 1.371 | 0.896 |
Pond in the Kamysh-Burun iron ore quarry, 06.08.2013 | 0 | 0.090–0.144 | 0.10–0.50 | 12 | 10.193 | 1.914 | 0.718 | 0.519 |
Lake Kuchuk- Adzhigol, 07.07.2016 | 10 | 0.103–0.194 | 0.13–0.84 | 136 | 1.588 | 1.130 | 0.332 | 0.835 |
n – number of measured larvae; c, d – coefficients of equation (4); W0.250 – calculated mass of larvae with 0.250 mm width of head capsule; R – coefficient of correlation
where D – the width of the head capsule, mm; L– the body length, mm; W – the body mass, mg; k, m, c, d , a and b– the coefficients.
Average values, standard deviations (SD) and coefficients of variation (CV) were calculated. The significance of differences in mean values was evaluated by Student’s t-test and the confidence level of the correlation coefficients was determined (Müller et al. 1979).
and the second one (R = 0.921,
The calculated width of the head capsule in one-size larvae (7 mm) was 0.551 mm in one group and 0.253 mm in the other; the values differed 2.2 times. The authors analyzed the effect of salinity on the width of the head capsule in two groups (Fig. 3). Salinity affected the width of the head capsule in the group with wider head capsule; it may be approximated as (R = 0.997,
where S– salinity, PSU.
A weak positive correlation was found for another group (R = 0.569,
where W7 – the mass of 7 mm long larvae, mg; S – salinity, PSU, and the equation (R = 0.902,
No correlation was found between the mass and its ratio to size traits and temperature and pH.
The authors also calculated the equation using all measurements (1167) for this species (R = 0.898,
The mass of 7 mm larvae, calculated using this equation, was 1.039 mg. This value is 2 times smaller than the largest mass in the analyzed samples and 2.7 times larger than the smallest mass in those samples (Table 3).
Table 4 presents the parameters calculated by equation (3). Parameters for different samples differed greatly in the case of
Based on the available published data, the power coefficients “m” in parabolic equation (2) describing the relationship between the width of the head capsule and the body length of chironomid larvae representing seven species were calculated:
The exponent “b” in equation (3) describing the relationship between the body mass and the length of chironomid larvae significantly varied in our data (Table 3) – from 1.566 to 3.057. Values of this parameter provided in the available literature and calculated by the authors of this paper using published data also vary over a wide range:
The exponent “d” in equation (4) of the relationship between the body mass and the width of the head capsule in chironomid larvae (Table 4) varied significantly in our data – from 1.130 to 3.378, i.e. in a wider range than in the equation of the relationship between the mass and the body length. In the literature, the following values of this coefficient are available:
Two phenotypically distinct morphs differing in body size and body proportion were found among chironomid larvae of the studied species. A similar population polymorphism was observed in various animal taxa and it is assumed that it increases the adaptability of populations (Huston & DeAngelis 1987; Anufriieva & Shadrin 2014b). Such polymorphism may result from the interaction of different environmental characteristics with a population gene pool and the critical factors, which include: (1) growth rate variations among individuals resulting from intra-population metabolic communications; (2) polymorphism in a population gene pool; (3) epigenetic diversity resulting from alternative gene expression and epigenetic mechanisms (Huston & DeAngelis 1987; Goldberg et al. 2007; Anufriieva & Shadrin, 2014b). “The phenotype can be represented as a branching system of trajectories in a phase space spreading along the time axis” (Waddington 1940).
When comparing the results obtained with fixed and non-fixed larvae of chironomids, it should be considered that with prolonged storage in formalin or alcohol, larvae can lose on average 20–30% of their original mass (Donald & Paterson 1977). Taking this into account, it should be assumed that in our study there were cases of larvae mass underestimation. It is likely that the “a” and “c” indicators in equations (3) and (4) should be increased by 20–30%. We assume that when the larvae of different sizes were fixed, their mass loss was at the same rate, and, consequently, the coefficients “b” and “d” in equations (3) and (4) for the living body mass remained unchanged.
General conclusions: when analyzing populations and taxocenes of chironomid larvae in different water bodies, it is inappropriate to use general equations for the mass–body relationship with linear traits. Salinity affects the larvae mass and “length–mass” ratio but cannot be considered as a single factor affecting the size and mass of chironomid larvae in water bodies. All factors act together. More detailed studies of the effects of various factors (salinity, temperature, oxygen concentration, quality and quantity of food, etc.) on the parameters of the equations are needed.