Macro-benthic algae Catenella nipae was cultured from November '06 to August '07 at the Salimpur planted mangrove area of Chittagong Coast. Growth of the cultured C. nipae on bamboo poles was measured during the investigation period. Average growth of C. nipae on bamboo poles was recorded 0.19cm/day. Physico-chemical parameters of water and soil were recorded during culture period in the tidal swamp of Salimpur mangrove area. Water temperature ranges from 24.0 to 31.5˚C, salinity from 6.0 to 21.0‰, dissolved oxygen (DO) from 3.8 to 5.8ml/l, water pH from 7.2 to 8.4, total dissolved solids (TDS) from 410 to 598mg/l, , total suspended solids (TSS) from 50 to 118mg/l, Total alkalinity from 95 to118 ppm, NO₂-N from 0.18 to 0.47mg/l, NO₃-N from 0.56 to 0.69mg/l, PO₄-P from 0.90 to1.10 mg/l, HCO₃ from 69.88 to 93.80mg/l, were recorded during culture period. Soil organic carbon, organic matter, soil PO₄-P, soil pH were ranges from 2.22-2.37%, 4.22-4.51%, 1.10-1.39mg/100g and 5.9-6.7, respectively in the culture area. Growth of C. nipae showed a significant positive relation with water and soil parameters such as dissolved oxygen (DF=17, P=0.006, t=3), NO₃-N concentration (DF=17, P=0.055, t=2) and a negative correlation with HCO₃ concentration (DF=17, P=0.004, t=3). Physico-chemical parameters of both water and soil revealed that the coastal area of Salimpur could be a significant place for commercial culture of seaweeds C. nipae in Bangladesh.

Seaweeds are sedentary organisms, growing on the rocky or hard substratum of intertidal water of World Ocean.¹ They belong to the group of plants known as algae containing some of the most primitive members of the plant kingdom.² Okazaki³ stated, “Seaweeds as the name implies covers the macroscopic plant life of the sea except for the flowering plants". It has immense importance both for human and faunal communities. Prehistorically, people have been consuming seaweed either raw or cooked condition. Novaczek⁴ reported that seaweeds have large amount of protein, amino acids, lipids, vitamins and minerals, polysaccharides and dietary fibers. Some compounds of seaweeds control high blood pressure, level of cholesterol, and prevent strokes. These can also be used as remedy for rheumatism, diarrhea, and for controlling the growth of tumors.

The culture of seaweed for human consumption is a relatively new enterprise. The concept of seaweed and its cultivation is limited to the scientific community, people hardly known about its importance and culture technique in developing countries. The status of seaweed cultivation in Bangladesh is still at the nascent stage.

The study is first experiment of Catenella nipae culture on bamboo poles in the intertidal waters of Salimpur coast in Bangladesh where plenty of C. nipae grows naturally remains unutilized for long time. In addition, now-a-days utilization of algae as human food has been increasing in many countries like China, Japan, Philippines and Myanmar.⁵ Whereas the mass people of Bangladesh do not know that the algae can be used as human food.

The investigation was carried out from November 2006 to August 2007 at Salimpur mangrove area. Bamboo poles were used for culture of Catenella nipae. A total area of 5mx5m was selected. To culture C. nipae on bamboo poles, at first bamboo poles were collected and cut into 0.5m size length each. Within the culture area bamboo poles were installed maintaining 0.5m distance between two consecutive poles. Then body segments of C. nipae from the nature were collected and were attached in the bamboo poles with the help of thread. Routine checked of the culture system was done. After each three months interval culture experimental algal species was collected carefully with the help of a sharp knife and taken in to plastic bag. Water and soil sample were collected from the intertidal mangrove areas of Salimpur coast during study period and analyzed using standard methods APHA.⁶

Measurement of growth

The average daily growth was observed as 0.19+ 0.11cm during the culture period. Maximum daily average growth was 0.29cm in August 2007 and minimum value was recorded 0.11cm on July 2007 (Table 1). There is no major trend of fluctuation for the growth of C. nipae in the culture period. Growth of Catenella nipae shows a positive correlation with DO (DF=17, P=0.006, t=3) and NO₃-N (DF=17, P=0.055, t=2) concentration. A negative correlation was found between growth of Catenella nipae & HCO₃ concentration (DF=17, P=0.004, t=3). 

Abundance of pneumatophores and natural biomass

In the present study the in parallel with culture performance growth of C. nipae was measured in the natural environment. The average number of pneumataphores found as 79.1+7.73 and average natural biomass content was found 159.10+41.14 g/m² (Table 2) whereas the maximum values in per pneumatophore was recorded on November (2.90) and minimum value was on March (1.52). A Significant relationship was found between number of Pneumatophores and biomass of Catenella nipae of the Salimpur mangrove area (t=3, P=0.0106, DF=29) and it was observed that biomss is proportionally related with the availability of water. 

Harvesting

After the culture period of three months, Catenella nipae colony weight on average was found as 176+4.97g on the bamboo poles. 

Water and soil parameters

The average water temperature was recorded as 29.05+2.45˚C whereas highest value (31.5˚C) was recorded on June 2007 and the lowest 24˚C in February 2007, average salinity was 14.30+5.35‰, highest salinity was recorded 21‰ on March 2007 and lowest 6‰ on August 2007, average D.O was (4.95+0.62ml/l) where highest 5.80ml/l on July and lowest value 3.80ml/l on December 2007, average pH was (7.78+0.37) where maximum was 8.4 on February 2007 and minimum was 7.2 on August 2007, average TDS was (541.10±59.35mg/l) where highest value 598.00mg/l was recorded on July 2007 and the lowest value 410.00 mg/l on February 2007, average TSS was (76.30±22.01mg/l) where the highest value 118.00 mg/l was recorded on Augus 2007 and the lowest value 50.00mg/l on April 2007, average alkalinity was (107.40+6.92ppm) where maximum 118.00 ppm was on February 2007 and the lowest value 95 ppm on August 2007, average NO₂-N as 0.34+0.09mg/l where highest NO₂-N value was found 0.47mg/l on June 2007 and lowest value 0.18mg/l was recorded on February 2007 average NO₃-N was 0.65+0.05mg/l where highest NO₃-N value was found 0.69mg/l on May 2007 and lowest value 0.56 mg/l was recorded on January 2007, average PO₄-P was recorded as 0.99+0.06 mg/l where , highest PO₄-P value was found 1.10mg/l on January 2007 and lowest value 0.90mg/l was recorded on June 2007, average HCO₃ was observed as 81.33+4.50mg/l where highest HCO₃ value was found 93.80mg/l on June 2007 and lowest value 69.88mg/l was recorded on February 2007and average BOD was recorded 1.86+0.17ml/l where highest value was 2.16ml/l on November 2006 and lowest value 1.56ml/l on June 2007 respectively in the study area (Table 3).

The average soil organic matter was recorded as 4.39+0.10%, the highest value was 4.51% was recorded on January 2007 and the lowest value 4.22% in July 2007. The mean organic carbon was recorded as 2.31+0.05%, the highest value was 2.37% was recorded on November 2006 and January 2007 respectively and the lowest value 2.22% on July 2007. Average PO₄-P was observed as 1.28+0.10mg/100g. Highest PO₄-P value was found 1.39 mg/100g on August 2007 and lowest value 1.10 mg/100g was recorded on March 2007. The average soil pH was 6.30+0.28. Maximum soil pH 6.7 on January 2007 and minimum value was recorded 5.9 on August 2007. The soil texture of the study area was sandy clay loam. Sand ranges from 67.00% to 72.68%, Clay ranges from 23.69% to 29.60%, Silt ranges from 2.50% to 5.11% during the whole study period (Table 4) (Table 5).

Growth performance of C. nipae

In the present study the daily growth was observed 0.19cm/day on the bamboo poles in an average which suggest a suitable rate for culture of this alga in this area. And growth of the cultured algae showed a significant positive relation with dissolved oxygen (DF=17, P=0.006, t=3) (Figure 1), NO₃-N concentration (DF=17, P=0.055, t=2) (Figure 2), and a negative correlation with HCO₃ concentration (DF=17, P=0.004, t=3) (Figure 3).

Figure 1 Scatter diagram showing relation between DO and growth.

Figure 2 Scatter diagram showing relation between NO₃-N and growth.

Figure 3 Scatter diagram showing relation between HCO₃ and growth.

Soe-Htun et al.⁷ reported luxuriant growth of Catenella on the bamboo stakes in an experimental culture in Myanmar. These were harvested using a spoon. The yield of Catenella was about 40-50g (wet-wt.) per bamboo stake (Figure 4).

Figure 4 Graphical presentation of monthly biomass content in each pneumatophore.

There are the components in sea water in concentrations of mg-atoms/m³ that are of fundamental importance to the growth of marine algae, the base of the food chain in the sea. These components are soluble inorganic phosphate (0.1-3.5mg-atoms/m³), nitrate (0.1-43mg-atoms/m³), nitrite (0.1-3.5mg-atoms/m³), ammonium (0.35-3.5mg-atoms/m³), and hydrated silicate ions (0.1-170mg-atoms/m³). These marine fertilizers are consumed only in the upper layers of the ocean where light conditions permit photosynthesis and are often limiting to growth.⁸ 

Physico-chemical parameter

The growth of seaweeds is governed by various factors like temperature, salinity, pH, dissolved oxygen, water transparency; nutrients Lunning.⁹ His studies found that for the growth of tropical seaweeds the optimum water temperature ranges between 15-30˚C. The findings of the present investigation is exclusively agreed with the above mentioned report.

Meade¹⁰ recommended standard water quality for aquaculture as water pH 6.5-8, DO 5mg/l, and alkalinity 10-400ppm. The mean D.O value was found (4.95+0.62)ml/l in the present investigation which is quite satisfactory for normal growth and functioning of aquatic organisms. While the standard values of D.O of the coastal water of Bangladesh is 6ml/l.¹¹ So the present findings are exclusively agreed with the above information.

The environmental quality standard value of pH of coastal water of Bangladesh is 6-9. Zafar¹² found, the water temperature, salinity, pH, DO ranged from (30-33˚C), (6-16ppt), (6.9-7), (2.95-5.77ml/l) at the Fauzdarhat planted mangrove area. The present study also showed a similar trend of results.

Hossain¹³ recorded water temperature, salinity, water pH, DO ranged from (20-29˚C), (6.5-16ppt), (6.8-7.4), (3.77-5.50ml/l) at the Fauzdarhat mangrove area. In the present investigation recorded water temperature, salinity, DO, water and soil pH were more or less similar to the above mentioned report.

Talukder¹⁴ recorded water temperature ranged between 11.65-31.40˚C, water pH 6.27- 7.75, dissolved oxygen 2.34-5.71ml/l, salinity ranges from 6.51-16.30 ppt, total suspended solids ranges between 112.03mg/l to 343.34mg/l, total dissolved solids 377.16mg/l to 573.32mg/l, PO₄-P ranges from 1.01-4.68ml/l, NO₃-N varied from 1.15-3.34ml/l, BOD 2.95-6.63ml/l, soil pH 5.30-7.70 in a study on macrobenthic algae of the Fauzdarhat coast, chittagong. The findings of the present investigation are apparently similar to the above mentioned report.

Chowdhury¹⁵ reported the micronutrients of the coastal water of Cox’s Bazar and recorded maximum (NO₂-N=1.520µ-g at/l, PO₄-P=1.804µ-g at/l and SiO₃-Si=46.62µ-g at/l) during July to August and minimum (NO₂-N=0.084µ-g at/l, PO₄-P=0.224µ-g at/l and SiO₃-Si=3.28µ-g at/l) during November to December respectively. Noori (1999) reported the micronutrients concentration of the coastal water of southeast coast of Bangladesh and recorded maximum (NO₂-N=1.198µ-g at/l, PO₄-P=2.330µ-g at/l and SiO₃-Si=63.31µ-g at/l) during May to August and minimum (NO₂-N=0.020µ-g at/l, PO₄-P=0.075µ-g at/l and SiO₃-Si=0.673µ-g at/l) during September to December respectively. The findings of the present investigation are apparently similar to the above mentioned report.

Grant¹⁶ recoded the inter-tidal soil pH ranged from 7.6 to 8.1 from the inter-tidal sand flat of North Inlet, South Carolina, U.S.A. Islam¹⁷ recorded pH values ranged from 6.35 to 6.85 in bottom sediment collected from lower Meghna river estury during premonsoon. Present findings are more or less similar to these above mentioned report.

Within the marine sediments there is generally a decrease in organic content with depth in the deposit. Correns,¹⁸ Revelle and Shepard¹⁹ have all reported this characteristics distribution. Connell,²⁰ obtained a linear relationship between organic matter and calcium carbonate and concluded that calcareous material contained about 0.2% organic matter and having no calcareous material contained a constant proportion of organic matter. Kondalarao and Murty²¹ reported that organic matter of intertidal zone of the Kinda bay, east coast of India was 0.70% to 2.17% which is closely similar to the present observation where organic matter varied from 4.22% to 4.51%.

Vizakat et al.²² expressed that the texture of sediment as silty clay’sand silts; silty sand of the subtidal soft sediment of the west coast of India. Alam²³ recorded the seasonal variation of sediment percentage in the Halishahar coast; Chittagong and he found maximum sand percentage in monsoon and minimum in winter, which is similar to the present investigation.

Growth of Catenella nipae shows positive relation with physico-chemical parameter of water viz. with T.S.S (r=0.43355), NO₃-N(r=0.0.2485), NO₂-N(r=0.963417), PO₄-P(r=0.0.612974), BOD (r=0.0.579897) and negative relation with DO (r=-0.44623), Temperature (r=-0.51815), HCO3 (r=-0.79903), pH (r=-0.99814), T.D.S (r=-0.99593), Total alkalinity (r=-0.79447) in the present investigation. Soil parameter viz. organic matter (r=0.997018), organic carbon (r=0.998137), PO₄-P (r=0.999554) shows positive relation and soil pH (-0.55191) shows negative relation with growth.

If the proper steps are taken for seaweed culture and management, it may open a new avenue for the local farmers, creating an alternative livelihood option. Thus, phyco-aqua industry will come as an indicative tool for national economic emancipation, poverty alleviation, mitigating unemployment problems and finally maintaining socio- economic condition of the coastal poor communities of Bangladesh. No systematic study on this economic seaweed has done in Bangladesh before. Therefore, the present study can be the path-finder on the detailed study of specific seaweed for the enrichment of the study of phycology in Bangladesh.

None.

None.

The authors declare there are no conflicts of interest.

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