Habitat suitability index of Barbus cyri (Heckel, 1843) in Tootkabon River, the South Caspian Sea basin, Iran

Habitat suitability index of Barbus cyri (Heckel, 1843) in Tootkabon River, the South Caspian Sea basin, Iran

H. Asadi¹*, M. Sattari¹, S. Eagderi²

1- Department of Fisheries, Faculty of  Natural Resources, University of  Guilan, Sowmeh Sara, Guilan, Iran.

2- Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran.

* Corresponding author’s E-mail: asadi.shil@gmail.com

ABSTRACT

Knowledge of habitat requirements of aquatic animals plays an important role in fisheries and protection programs of aquatic ecosystems. Hence, this study was conducted to investigate the suitability indexes of habitat use and habitat suitability index (HSI) of Barbus cyri in its distribution range in Tootkabon River. A number of environmental variables, including elevation, water depth, river width, river slope, velocity, substrate type, and average diameter of bed stone, riparian vegetation type and the relative abundance of B. cyri at 13 stations and three replications from the downstream to upstream were examined during November 2013.  The results showed that B. cyri mostly selects upper stretches of the river with higher velocity, middle depth, lower width and bed rock substrate i.e. bed with boulder cover and grasslands and also its residential area is of riparian type compared with the available ranges. Habitat selectivity index for B. cyri showed that the elevation is 130-220 m, water depth 18-75 cm, channel width less than 12 m, channel slope 0.5-2.3%, water velocity less than 0.8 m.s^-1, bed rock substrate, average diameter of bed stone larger 15-50cm. Presence of these conditions with HSI of 0.798 indicates that Tootkabon River is an excellent habitat for B. cyri.

INTRODUCTION

Changes of the hydrological features in a riverine ecosystem by anthropological activities such as habitat destruction can negatively affect survive, reproductive success and growth rate of aquatic organisms particularly fish species (Rosenfeld, 2003, Ahmadi-Nedushan et al. 2006) threatening their survival. Therefore, as first step to assess the impact of human activity on riverine ecosystem and protection of their biodiversity, understanding the habitat requirements of its organism is crucial (Vinagre et al. 2006). Hence, Habitat Suitability Indices (HSI) of an aquatic species is one of the primacy themes in river ecology to predict the effect of human manipulation due to the alternation of the

riverine hydrological features (Guay et al. 2000). Hydrological characteristics of a river play an important role in fish distribution affecting their metabolism rate, feeding and behavior (Jowetl et al. 2007). Habitat selection means that a fish species is more abundant in a specific habitat which is suitable (Rosenfeld 2003). Many environmental factors are important to affect fish in selecting its preferred habitat (Bovee 1982). Nevertheless, most of the models to study the habitat suitability of an riverine species use the hydrological parameters such as depth, current velocity, river width, type of river bed, river slope, elevation,  and river vegetation (Orth 1988) as important factors.

Kura barbel, Barbus cyri (De Filippi 1865) is a cyprinid species native to the Caspian Sea basin (Esmaeili et al. 2014a, b). This species bears a fusiform body shape, small scales, inferior mouth, and thin lips with two pairs of barbels (Fig. 1). Berg (1948-1949) refers Caspian Sea basin specimens to Barbus lacerta cyri, but this subspecies recognized as a valid species by Naseka & Bogutskaya (2009).

Little information is available regarding biology and ecology of B. cyri, particularly its habitat use and habitat suitability indexes are unknown. Therefore, this study was conducted to assess the habitat use and habitat suitability indexes of B. Cyri with respect to habitat availability of this species in Tootkabon River, a branch of the Sefidrud River in the Southern Caspian Sea basin.

Fig. 1.  Barbus cyri caught from Tootkabon River.

Fig. 2. Location of Alborz Province, Tootkabon River and sampling points.

Table 1. Explanation and abbreviation for each categorical habitat variable.

MATERIALS AND METHODS

Study area

Tootkabon River is a branch of the Sefidrud River in the Southern Caspian Sea basin, originates from the Alborz Mountains. The approximate length of this river is 23 km with an average slope bed of 6.1% (Fig. 2).

Sampling

For this study, we sampled fish and habitat variables in autumn 2014 during base flow conditions. Thirteen sampling stations were located across the Tootkabon River (Guilan Province, north of Iran) (Fig. 1). The elevation (m) and geographic coordinates were recorded for each station to ±10 m using GPS (Global Positioning System; Garmin) according to Torgersen & Close (2004). 

The river and the sampling point locations were mapped using ArcGIS 9.3 (Fig. 1).

Fish were sampled in 10-15 m stretches of the river using a backpack electrofishing device (Samus Mp750, 45cm diameter, aluminium ring anode) in the downstream–upstream direction using upstream and downstream stop-nets of 0.2 cm mesh. For sampling, one-removal method with similar catch-per-unit effort strategy was employed (Klaar et al. 2004).

Fish specimens were collected from each station during 30 min, anesthetized in clove powder solution (1 g.l^-1), identified according to Coad (2015), counted, photographed, and finally placed in slow - moving water along the river bank to recover and return to the river.

Since no comparable study on microhabitat use of this species was available, therefore, only the specimens larger than 40 mm were selected and counted in each station for further analysis; because the habitat use of fishes in lotic systems can be strongly affected by ontogeny (Copp & Vilizzi 2004; Gillette et al. 2006).

Habitat Data

Since there is limited or no knowledge available on the studied species, the environmental variables were selected according to the results of other studies conducted on other fishes (Chuang et al. 2006; Rifflart et al. 2009; Tabatabaei et al. 2015). The habitat data were measured immediately after sampling (Yu & Lee 2002).

The measured variables included water depth (cm), river width (m), Elevation (m) river slope (%), velocity (m.s^-1), substrate type (substrate index), average diameter of bed stone (cm), and riparian vegetation type.

Elevation of sampling sites were recorded by GPS (Garmin).

The mean depth (cm) of each station was estimated by measuring depth at 20 random points across sampling site using a measuring bar, considering  their average  as the river depth (Lotfi, 2012).

The mean width of river (m) was measured using a tapeline by measuring upper, middle and lower sections of each sampling station, considering their average as the river width. The surface velocity (m.s^-1) was estimated by a simple float based on Hassanlie (1999), repeating three times to minimize the error. Dominant substrate type was determined both visually and randomly via measuring the diameter of the riverbed stones in 20 selected quadrate (50 × 50 cm) based on Lotfi (2012), and then classified according to Johnston et al. (1996) and Tabatabaei et al. (2015).

The bed stone diameter average also were calculated by measuring diameter of bed stones in 20 selected quadrate (50×50 cm) based on Lotfi (2012). Riparian vegetation type (based on the type of vegetation growing at riparian zone of the river or absence thereof), were classified according to our observations, photographs, and standard procedures with some modifications (Johnston et al. 1996). The first six variables were continuous, and riparian vegetation type was nominal. The abbreviation and description for each discrete variable are presented in Table 1.

Data analysis

Habitat use, availability, and selection were calculated over the range of each environmental variable. Each environmental variable was divided into a series of intervals, and the mean relative abundance of fish in each interval was calculated using habitat selection (Habsel) software 1.0 (Jowett, 2014). The formula S = (%Uc,i)/(%Ac,i), where i is the interval of a given environmental variable c, %Uc,i is the percentage of utilization of a specific interval of an environmental variable utilized by fish, and %Ac,i is the percentage of availability of this environmental variable (Guay et al. 2000; Waddle 2001; Tabatabaei et al. 2015), resulted in a selectivity value (S) at each interval. The selectivity values were then scaled, so that the maximum value was one. The mean selectivity values of each environmental variable (scaled to the maximum value of one) was considered as SI value of the variables at each station. Habitat Suitability Index (HIS) was calculated using following formula (Guay et al. 2000):

HIS=

In this formula, all variables of a habitat are considered essential and the product equation yields zero suitability for any given unsuitable habitat variable.

Since here is no data available regarding the value of each selected variable, therefore, in this research, the SI is multiply to obtain HIS.

RESULTS

All collected fish during sampling belonged to 8 species viz. Barbus cyri, Capoeta graceless, Alburnus filipi, Cobitis keyvani, Ponticola iranicus, Ponticola cyrius, Alburnoides ssamiii and Oxynoemacheilus bergianus which were returned to the river after identification and counting. A total of 144 specimens of B. cyri were collected. Habitat use, availability, and selection are presented in Fig. 3. Table 2 summarizes the average data obtained from each sampling station and environmental variables in the study area are shown.

Table 2. Minimum, Maximum, Mean and Standard deviation of variables used.

The studied habitats in Tootkabon River mostly occurred in an elevation range of 175-200 m above sea level, with 0.55-0.69 cm depth, 2.8-4.2 m width, 0.60-0.75 m.s^-1 water velocity, slope of 0.5-1.75% and stone diameter of 25-30 cm, and cobble and then boulder substrate type, deciduous riparian forest, and with most available cover type of boulder (Fig. 2 and Table 3). The habitat-use pattern of B. Cyri generally followed habitat availability. Considering the availability of environmental variables and the selectivity, the habitat selection pattern of this species mainly had the following features: elevation 130-220 m, water depth 18-75 cm, channel width less than 12 m, channel slope 0.5-2.3%, water velocity less than 0.8 m.s^-1, bed rock substrate, average diameter of bed stone 15-50cm, and deciduous forest and residential area riparian type (Fig. 3). Suitability index values of environmental variables for B. cyri in Tootkabon River are shown in Table 4. Among of the variables studied, stone diameter had the most (0.81) and elevation (0.57) had the least amount. Calculation showed that the HSI river habitat suitability for B. cyri in Tootkabon River is 0.80. The results revealed that B. cyri mostly selected upper stretches of the river with higher velocity and bed rock substrate (Table 3).

Furthermore, this species selects lower depth and velocity, bed rock substrate i.e. bed with larger elements, deciduous forest and residential area riparian type, and boulder cover compared to the available ranges. In some cases, the pattern of habitat use was different from the pattern of habitat selection i.e. in water depth, river width and velocity.

Table 3. Mostly selected variables of B. cyri.

Fig. 3. Habitat availability (blue line), used (red line) and selected (black line) by B. cyri for environmental variables.

Table 4. Selected index for B. cyri in different stations.

Table 5. Habitat suitability for B. cyri in different stations.