3rdInternationalConferencesandWorkshopsonBasicandAppliedSciences2010ISBN:9789791909617

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The Limiting Nutriens of Algae Biomass During Dry Season in Mrica Reservoir of Banjarnegara, Central Java

Agatha Sih Piranti, Sudarmadji, Agus Maryono, Suwarno Hadisusanto

*Biology Faculty of UNSOED Purwokerto

** Geografi Faculty of UGM, Yogyakarta,

***. Engineering Faculty of UGM, Yogyakarta

**** Biology Faculty of UGM, Yogyakarta

Abstract

A limiting nutrient is a nutrient that is available in very small amounts needed for algae growth. Nitrogen and / or phosphorus is the nutrient that generally a limiting factor algae growth in aquatic ecosystem. The purpose of this study was to determine the type of the limiting nutrient of algae growth in the Mrica reservoir during dry season and determine the relationship model of that nutrient in determining the growth of algae in the Mrica reservoir Banjarnegara during the dry season. The result were that concentrations of both total phosphate (TP) and total nitrogen (TN) determined the growth of algae in the Mrica reservoir during dry season, however NO3/PO4 (the ratio of dissolved nitrogen and phosphorus) was more played as a factor of limiting algae growth. Model of the relationship between NO3/PO4 and algae biomass (chlorophyll) was to follow the following equation: CHLOROPHYLL = 20.14 - 0.9185 (NO3/PO4) + 0.02402 (NO3/PO4) 2 - 0.000196 (NO3/PO4) 3. Key words : limiting nutrient, algal biomass, Mrica reservoir, dry season

1 Introduction

Algae are a microscopic organisms that have a chlorophyll to make the process of photosynthesis. The role of algae in aquatic ecosystems is essential that as major chains in the food web, which provides food and oxygen to support life of aquatic animals. However, sometimes the algae can cause problems, when there's too much (indicated by chlorophyll concentration reached 40 mg/m3) that interfere with light penetration and create anoxic conditions (no oxygen), especially at night because the algae also utilize oxygen at night (Harper,

1992). Klapper (1991) states that when chlorophyll concentrations exceed 100 mg/m3 may cause fish kills due to toxins produced by these algae.

The main factors affecting biomass growth of algae in the waters of the nutrients (N and P) (Horne & Goldmann, 1994). Fried et al., (2003) stated that with the supply of nutrients into waters will lead to the development of certain algae (algae bloom) from the class of blue-green algae such as Cyanocacteria which can degrade water quality. Harper (1992) states that there is a very close relationship (correlation coefficient R = 0.9) between the phosphorus content of the biomass of phytoplankton. Therefore nutrients phosphorus becomes the limiting factor of growth of algae (nutrient-limiting factor).

A limiting nutrient is a very small amounts nutrient that is available in the aquatic environment that needed to algae growth. Once the limiting nutrient in a waterbody is exhausted, the population of algae stops expanding. If more of the limiting nutrient is added, larger algal populations will result until their growth is again limited by nutrients or by other limiting environmental factors. Nitrogen and / or phosphorus is the nutrient that generally a limiting factor in algae growth in waters (Florida lakewatch, 2000). However, the availability of N and P nutrients, algae growth is also determined by the conditions of supply of light, water mixing (mixing), water residence time, temperature, and predation by zooplankton These factors are complex and interact with each other so that the results are highly variable reflecting watershed conditions , land use and management patterns, the depth of the reservoir, shape and tidal reservoir conditions (Lawrence et al, 2000).

Based on the background and description of the problem then the purpose of this study was to

Agatha, The Limiting Nutriens of Algae Biomass During Dry Season in Mrica Reservoir of Banjarnegara, Central Java

B001

determine the type of nutrient limiting for the growth of algae in the Mrica reservoir Banjarnegara during dry season and determine the model of the relationship between the limiting nutrient and the growth of algae in the Mrica reservoir of Banjarnegara during the dry season.

2 Methodology

The research was conducted by a survey method in Mrica reservoir once a month during the dry season in the period March 2009 to February 2010 in locations as follows: 1) the estuary of the river Serayu, 2) estuaries Lumajang river, 3) estuaries Kandangwangi river , 4) riverine zone, 5) transition zone, 6) Middle Reservoir, 7) Floating Net area of Karangjambe 8) irrigation outlet area, 9) the area near the spillway, 10) the area near the power intakes, and 11) Tourism resort area. The nutrient samples were taken using a Grab sampling technique (sampling technique that not change the moment in a specific time period) and composite sampling technique (sampling at the same place with different time intervals). Research variable was the concentration of Total Nitrogen (TN), Total Phosphate (TP), orthophosphoric (PO4), nitrate (NO3) and ammonia (NH4). To examine the relationship of concentration of nutrients and algal biomass in the reservoir Mrica, then performed by a correlation analysis and proceed with the test correlation coefficient (R) (Hasan, 2004). Types of nutrients that have a real relationship with the highest degree of relationship with the growth of algae biomass is the nutrient limiting growth (growth-limiting factor) Mrica algae in reservoirs. To determine the model of the relationship between the type of nutrient limiting and algal biomass was perform by using regression equations between each type of limiting nutrient and algal biomass.

3 Result

Nutrients (nitrogen and phosphorus) is a nutrient that is closely associated with fertility status (trophic status) of a waters caused by human activities in the catchment area. In the reservoir ecosystem increased nutrient input into coastal waters will increase the algae biomass. Chlorophyll can be used to estimate the magnitude of the biomass of algae in the waters (Mason,1991 and OECD, 1982).

Based on the observations of nutrients and chlorophyll in the reservoirs Mrica during the dry season (June 2009 - October 2009) showed that TP and TN concentrations declined in the late dry season (October) as shown in Table 1. This is due

in that period of months there has been rain, causing a dilution water reservoir so that the concentration of nitrogen and phosphorus either in the form of particles or dissolved into decline. Basically at the end of the dry season or early rainy season has been an increased input of nutrients, especially TP DTA. This is evidenced from the declining value of the ratio NO3/PO4 to obtain the exact ratio that can cause the algae to multiply, causing an increase in algal biomass.

Based on the results of correlation analysis that the relationship between nutrients and chlorophyll in Mrica Reservoir during the dry season showed that all types of nutrients had a negative relationship with chlorophyll, except for PO4. The summarised results of the correlation analysis were illustrated in Table 2. Table 1: The average of nutrients and chlorophyll concentration in Mrica resevoir during dry season

Rata-rata konsentrasi nutrien dan klorofil Nutrien

jun jul augus

t sep

t oct TP 0.6 0.6 0.6 0.6 0.5

NO3 6.4 6.5 6.8 7.1 4.0

PO4 0.2 0.2 0.3 0.3 0.3

NH4 0.2 0.1 0.2 0.2 0.1

NO3/PO4 32 30 23 21 15

TN 8.1 7.9 8.4 8.8 5.6 KLOROFIL

9.1 9.4 9.2 9.1 12.2

Table 2: The results of correlation analysis of the relationship between nutrients and chlorophyll in the dry season in Reservoir Mrica

No Correlation (R) Relationship

1 TP Klorofil -

0.441 Negative, moderate / significant

2 PO4 Klorofil 0.109 Positive, very weak

3 TN Klorofil -

0.670 Negative, moderate / significant

4 NO3 Klorofil -

0.678 Negative, moderate / significant

5 NH4 Klorofil -

0.206 Negative, weak but definite

6 TN/TP - Klorofil -

0.116 Negative, very weak

7 NO3/PO4 - klorofil -

0.480 Negative, moderate / significant

3rdInternationalConferencesandWorkshopsonBasicandAppliedSciences2010ISBN:9789791909617

B001

Based on Table 2 showed that the relationship between TP and TN with chlorophyll showed a moderate or significant. This was indicated as correlation coefficient (R) of TP - chlorophyll were 0.441 and between TN - chlorophyll were 0.670. This indicates that both the TN and TP determined the developments algae biomass in the Mrica reservoir. To determine whether nitrogen or phosphorus or both, which acts as the limiting nutrient then the ratio both TN / TP and NO3/PO4 were calculated before the correlation analysis between the TN / TP and NO3/PO4 with chlorophyll were performed. Based on Table 1 showed that the results of correlation analysis between the TN / TP - chlorophyll showed a very weak relationship (R = 0116), whereas among NO3/PO4 - chlorophyll showed a moderate or significant (R = 480). This mean that the ratio of dissolved nitrogen and phosphorus or NO3/PO4 ratio was become a more determining factor in algae growth than the availability of TN and TP in the form of particles reservoirs Mrica. However, based on the correlation analysis then was constructed the regression line and obtained the algae growth model that follows the equation : CHLOROPHYLL = 20.14 - 0.9185 (NO3/PO4) + 0.02402 (NO3/PO4)2 - 0.000196 (NO3/PO4)3 as illustrated in Fig. 1 with a coefficient of determination (R2) of 44.1%. This meant that the amount of algae biomass in Mrica reservoirs could be estimated using the concentration ratio NO3/PO4 accordanced with the equation above with the confidence level of only 44.1%. The low confident as likely caused by environmental factors other than nutrients may become a limiting factors such as TSS algae growth, water color, flushing rate, and the presence makrofita.

4 Conclutions

During dry season concentrations of both nitrogen and phosphate acted as a nutrient limiting the growth of algae in Mrica reservoir Banjarnegara. However, the ratio of dissolved nitrogen and phosphorus (NO3/PO4) was more acted as a factor limiting growth of algae biomass in Mrica reservoir during dry season. The model of the relationship between NO3/PO4 and algae biomass (chlorophyll) was as the following equation : CHLOROPHYLL = 20.14 - 0.9185 (NO3/PO4) + 0.02402 (NO3/PO4)2 - 0.000196 (NO3/PO4)3.

NO3/PO4

KLO

RO

FIL

5040302010

15

14

13

12

11

10

9

8

7

S 1.20823R-Sq 44.1%R-Sq(adj) 40.8%

Fitted Line PlotKLOROFIL = 20.14 - 0.9185 NO3/PO4

+ 0.02402 NO3/PO4**2 - 0.000196 NO3/PO4**3

Figure 1: Plot and regression line of the

relationship between NO3/PO4 and chlorophyll

References

[1] Fried, S., Mackie, B., and Nothwehr, E., Nitrate and Phosphate Levels Positively Affect The Growth Of Algae Species Found In Pond Ferry. No. 4, pp. 21-24, 2003.

[2] Florida lakewatch, A Beginner's Guide To Water Management - Nutrients. Department Of Fisheries And Aquatic Sciences, Intitute Of Food And Agricultural Sciences, University of Florida, 2000.

[3] Harper, D., Eutrofication of Freshwater. Chapman & Hall. London. New York. Tokyo. Melbourne. Madras, 1992.

[4] Horne, A.J. and Goldman, C.R., Lymnology. Second edition. McGraw Hill, Inc.. New York, 1994.

[5] Klapper, H., Control Of eutrophication In Inland Waters. Ellis Horwood. New York. London. 1991.

[6] Lawrence, I., Bormans, M., Oliver, R., Ransom, G., Sherman, B., Ford, P. and Schofield, N., Controlling Algal Growth Factor And Composition reservoirs: Report Of Reservoir Manager's Workshops. National eutrophication Management Program., 2000.

[7] Mason, C.F., Biology of Freshwater Pollution. second edition. Longman Scientific & Technical. New York, 1991.

[8] Organization for Economic Cooperation & Development (OECD), Eutrophication of Water, Monitoring, Assessment And Control. Paris, 1982.