The Diversity of Fish in The Aek Sibundong District Dolok Sanggul Regency Humbang Hasundutan

. The diversity of fishes in Aek Sibundong, Dolok Sanggul regency, Humbang Hasundutan district, was conducted from April to October2018. The aim of this research was to analyze variety of fishes and their physical-chemical factors related to fishesin Aek Sibundong. This research used purposive sampling method on four location based on human activities. The first location was stationed with no activities, the second location tofu waste disposal station, the third location was slaughter house station and last location was belonge to sand dredging station. Sampling used nets as trap for the fishes. Seven species of fishes had been found from the sites where classified into 3 order ( spesies from ordo Cypriniformes 4, Perciformes 1 and Siluriformes 2). The result showed that station 1 had the highest fish density was 0,59 ind/m2 belong to Tor tambroides and the highest fish diversity index at 1,318. The temperature, light intensity, light penetration, phosphate, and Biochemical Oxygen Demand (BOD 5 ) had strongly correlated with fish diversity in the waters of the Aek Sibundong.


Introduction
The river is a form of aquatic ecosystem that has an important role in the hydrological cycle and functions as a water catchment area for the surrounding area, so that the condition of a river is strongly influenced by the characteristics possessed by the environment. Rivers have components and interact with each other to form an ecosystem that influences each other. River ecosystem components will integrate with each other to form an energy flow that supports the stability of the ecosystem [1]. Rivers are one of the important freshwater areas, according to [2] river is an

Station 2 research location
This station is a tofu waste disposal area located in Desa Sihite, the base substrate at this geographically muddy location is located 2º 15'24" N LU and 98º 44' 90" BT as in Figure 2.

Station 3 research location
This station is a waste disposal area of slaughterhouses, located in The Village of Aek Lung, the basic substrate at this location is geographically muddy located at 2º 13'50" N LU and 98º 46' 34" BT as in Figure 3.

Station 4 research location
This station is a sand-dredging area located in the village of Lumban Purba, the basic subsrat at this location rocks and sandy geographically trletak at 2º 13 ' 36 ' LU and 46º54 ' 98 ' BT as in

Fish Sampling
The sampling location is determined based on the Purpose Sampling method by determining 4 research stations. Each station is determined based on the activities contained in Aek Sibundong.
Fish sampling is carried out in conjunction with measurements of the physical-chemical of the waters. How to sample fish is done by spreading nets with an area of 12.56 m 2 and a net eye size of 1.5 cm 40 repeats at each station. The fish samples obtained are calculated in length and then measured in length using a ruler, weighed by digital scales and put in a plastic jar measuring 5 kg and preserved using 70% alcohol then taken to the laboratory to be identified using [5].

Temperature
Temperature measurements are done using a thermometer with a scale of 0 to 100°C. The thermometer is inserted into the body of water and leaves it for a while and then reads the thermometer scale and records the results listed on the thermometer scale.

Light intensity
The lux meter is placed at the research site after it is first turned on and sets the lux meter at an magnification of 200,000, then records the value listed on the screen.

Penetration of light
Measurement of light penetration is done using pieces of sechii, the way with pieces of sechii is put into river water until the piece of sechii is not visible then measured the length of the rope.

Dissolved oxygen (DO)
Measurement of dissolved oxygen is done using the Winkler method, which is a sample of water inserted into a Winkler bottle, then adds 1 ml of MnSO 4 and KOH-KI respectively to the bottle and is homogenized. The sample is silenced briefly until a white deposit is formed, then added 1 ml of H 2SO4, homogeneous and silenced until brown deposits are formed. The sample is taken 100 ml and put into the erlenmeyer and then titrated with Na 2S2O3 0.0125 N to pale yellow, then the sample drips with 5 drops of amylase and is homogeneous until a blue solution is formed.
Then the sample was titrated using Na 2S2O3 0.0125 N until the discoloration became apparent.
The volume of Na 2S2O3 0.0125 N used is calculated and the result is recorded.

Degrees of acidity (pH)
The measurement of the pH of water is done using a pH meter. Previously calibrated pH to pH = 7.
Then the pH meter is put into the water and then reads the values and records the results listed on the pH meter scale.

Speed of River Current
The speed of the current is measured using a pimpong ball inserted into the body of water along with turning on the stopwatch until it reaches a distance of 10 m. Then the stopwatch is turned off and the time is recorded.

Biochemical Oxygen Demand (BOD 5)
International Journal of Ecophysiology Vol. 03, No. 02, 2021 | 206-225 The BOD5 measurement was taken after the water sample taken was inc incusted for 5 days, then measured using a DO meter, then recorded the listed value. The BOD 5 value is obtained from the results of the initial DO measurement with the final DO after the incubation period of 5 days.

Oxygen saturation
Oxygen saturation value (%) can be calculated using formula As follows:

Nitrate levels (NO 3)
Water samples were taken as much as 5 ml, then added 1 ml of NaCl with volume pipette and

Posfat Level (PO 4)
A sample of water is taken as much as 5 ml and then added 1 ml of armstrong reagent and 1 ml of ascorbic acid. The solution is left for 20 minutes, then measured with a spectrophotometer at λ = 880 nm. Then the values listed on the spectrophotometer.

Data Analysis
The fish data were analyzed by calculating population density, relative density, frequency of attendance, Shannon Wiener diversity index, uniformity index and equality index formula [6,7].:

Relative Density (RD)
If kr >10% then a habitat is said to be suitable and suitable for the development of an oeganism [8]

Types of fish
From the research that has been done on the Aek Sibundong, obtained 7 types of fish as seen in Table 1 below. Information : : + Found -: Not found Table 4.1 shows that the types of fish obtained from the four research stations consist of 3 orders of 5 families and 7 species of fish. The most common types of fish in the family cyprinidae which number 4 types, this is because the family cyprinidae has a wide variety of species and is able to adapt to changes in environmental conditions. According to [9] Cyprinidae is the largest family of freshwater fish, consisting of 220 genera and 2,420 species. The number of species from the family Cyprinidae demonstrates the ability of this family to adapt and multiply rapidly. Clarias tjesmani and Puntius binotatusa are the types of fish found at every research station because the physical-chemical condition of the waters supports the growth and development of these fish.
Clarias is a species that adapts easily to its environment and has a high survival, this species tends to like mud-substrat water. Clarias tjesmani is a species that has additional breath organs that allow it to live in an environment lacking oxygen and outside the water so that its habitat is on a muddy substrate, flooded and shallow water so that it can move even though there is no running water [5]. Puntius binotatus can be found in various types of waters and conditions of chemical physics parameters of different waters living in the freshwater waters of the tropics with a pH range of 6.0-7.5 and water temperatures of 24-26º C and have a lifestyle of eating all kinds of food in the waters [10] Description of fish:

Puntius binotatus (Kaperas fish)
Round and flat body shape, superior mouth type, cycloid scale type, homocercal tail type silvery gray body color. This fish has a total length: 9-13.4 cm; standard length: 6.9-8.1 cm; head length:

Density, Relative Density, and Frequency of Fish Presence
Rasbora sumatrana is only found in station 1 because station 1 is an activity-free area and is a rocky area control area that has clear waters and calm influences. According to [11]  According to [9] family bragidae is a freshwater mustachioed fish that can live in murky water and is active all day often found in rivers, swamps and lakes.
The highest K, KR and FK values on station 4 are Oreochromis niloticus and are only found in station 4. The high value of the species is because station 4 is a sand-dredging area that has environmental conditions suitable for the habitat of Oreochromis niloticus who likes slowflowing water and sand-substrate and has a high tolerance to temperature. According to [13].
Oreochromis niloticus inhabits freshwater habitats including shallow waterways, rivers and lakes.
In addition, station 4 has a higher oxygen saturation between the four research stations so that the presence of dissolved oxygen in this station is more optimal and more supportive of the growth of the species, the suitable temperature in this species ranges between 14-38ºC and pH 5-9.
Cyprinus carpio is only found in station 4 because Cyprinus carpio likes freshwater habitats whose water is not too deep and the flow is not too heavy, such as on the banks of rivers or lakes. According to [14] Cyprinus carpio is very sensitive to changes in environmental quality.
This species is one of the fish that live in fresh waters that are not too deep and the flow of water is not too heavy, Cyprinus carpio can live at a temperature of 25-30 ° C

Species Diversity Index (H') and Equitability Index (E)
The uniformity index value (H') of the fish uniformity index (E) can be seen in table 3 below. According to [15] the value of the uniformity index ranges from 0-1. The criteria for the uniformity index value is that if E is close to 0 then the equality between species is low, meaning that the individual wealth that each species has is very much different and if E is close to 1 then the equality between species is relatively even or the number of individuals of each species is the same. Based on the results of the diversity and uniformity index shows that fish in these waters are classified as less diverse (H'<1) and E close to 0.

Parameters of Physical Chemical Factors
Measurement of the physical chemical factors of the waters in Aek Sibundong from the results of research at each station can be seen in Table 3 below:

Temperature
The water temperature value at the research site is in the range of 23-27ºC. The lowest temperature is in station 1 which is 23 ºC and the highest temperature is in station 4 which is 27 ºC. The temperature value at station 4 is higher than other stations can be caused by the intensity of light at the station is relatively high so that the penetration of light entering the water is also higher which results in higher temperatures at the station. According to [16] the optimum temperature range for organisms in tropical waters is 20 ºC -30 ºC. If the temperature is low the fish will lose its appetite, so that its growth is hampered, on the contrary, if the temperature is too high the fish will stress and even die of lack of oxygen.

Intensity of light
The intensity of light at each location of this study ranged from 370-390 candela. The highest value is at station 4 while the lowest is at station 2. The intensity of light greatly affects phytoplankton and periphytons in a water. According to [17] most periphytons act as producers who can carry out photosynthetic activities. Photosynthesis can take place well if the intensity of light that perifiton receives is sufficient. Therefore light is an environmental factor that determines the productivity of a water. Phytoplankton and periphytons are partly the natural food of fish.

Light Penertation
Light penetration at each study site ranges from 40-65 cm. The highest value is found at station 1 because the water is still clear at this station and the lowest at station 2. The low value of light penetration in station 2 is due to the presence of dissolved materials such as waste and also due to rainfall that causes the color of water to become cloudy so as to inhibit light from penetrating the waters. According to [6] the condition of turbid water caused by suspended solids will affect water quality because it will reduce the ability to penetrate light. High levels of turbidity can interfere with fish life in search of food, vision, and breathing. The higher the level of turbidity, the light that enters the body of water will also decrease, consequently disrupting the process of vision of prey / food [18]

Potential of Hydrogen (pH)
The results of the measurement of the degree of acidity in the research location ranged from 6-7.5. This pH range is still at the threshold for tropical waters and supports fish life. According to [2] life in water can still survive if the waters have a pH range of 5-9. The pH at the research site is still suitable for fish growth.

Dissolved Oxygen (DO)
Dissolved oxygen (Dissolved Oxygen) is needed by all living organisms for respiration, metabolic processes or the exchange of substances which then produce energy for growth and reproduction [19]. Water dissolved oxygen in Aek Sibundong at each station was in the range of 5.2-6.2 mg/L with the highest value at station 1 and the lowest at station 3. The highest dissolved oxygen value was at station 1, which was 6.2 mg/L. L because this research station is an area not exposed to human activities. According to [20] water conditions are suitable for supporting fish life, the amount of oxygen content is above 6 ppm. The rate of diffusion of oxygen from the air depends on several factors, such as water turbidity, temperature, and the movement of water masses (currents and waves).

Biochemical Oxygen Demand (BOD 5)
The result of measuring the BOD5 value at the four stations is a determination of the level of pollution of a waters. The BOD 5 value at each research station was in the range between 2.07-3.5 mg/L. Good waters that have BOD 5 levels ranging from 0-10 mg/L, while BOD values ranging from more than 10 mg/L are categorized as polluted. Biological oxygen demand is the amount of oxygen needed by microorganisms in environmental water to break down (degradate) organic waste materials in the environmental water. The number of microorganisms depends on the level of cleanliness of the water. Clear water usually contains relatively few microorganisms compared to water that has been polluted by waste materials (Wardhana, 2004).

Nitrate
Nitrates have an important role for the life of fish in the waters, the measurement results of the four research stations are in the range between 3.21-4.32 mg/L. The highest value is at station 2, the lowest is station 1, this is because the factors that affect water quality at station 2 are tofu waste disposal areas. Nitrates can be used to classify water fertility levels. Oligotrophic waters have nitrate levels between 0-1 mg/L, mesotrophic waters have nitrate levels between 1-5 mg/L, and eutrophic waters have nitrate levels ranging from 5-50 mg/L [2]. Nitrate levels in Aek Sibundong are still good enough to support fish growth.

Phosphate
The results of measurements of phosphate levels at the four research stations ranged from 0.02-0.03 mg/L, the highest value of phosphate levels was at station 2. According to Silalahi (2010), the phosphate content in the waters generally does not exceed 0.1 mg. / L, except in waters polluted by household and industrial waste, as well as agricultural areas that use phosphate fertilization that enters the river through drainage and rainwater flows.

Pearson Correlation Analysis Values
Pearson Correlation Analysis was obtained by analyzing the relationship of diversity and physical-chemical factors of Aek Sibundong waters using the pearson method. The correlation index value (r) can be seen in the following table 4.