Perbandingan Rekruitmen Spat Bivalvia Pada Ekosistem Mangrove Rehabilitasi Dengan Mangrove Alami di Pulau Rangsang, Provinsi Riau
Date
2023-07Author
Oktavian, Rizki
Bengen, Dietriech G
Natih, Nyoman M. N.
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The life cycle found in mangrove bivalves in their growth into adult shells are spat. Spat is a juvenile that has settled on the bottom of the water in an area that is still small with a shell shape resembling an adult shell and will grow and develop in that area. Spat growth until it becomes an adult clam, takes place in the mangrove ecosystem area in brackish waters. The importance of the economic value of bivalves makes the availability of seeds very important. Knowing the type, abundance and life cycle of bivalves is the right step in estimating the ideal time for spacing bivalves.
The research was conducted in a natural and rehabilitated mangrove ecosystem on Rangsang Island, Meranti Islands Regency, Riau Province, for 4 (months) months, starting from October to January 2021. The sampling location for
A. granosa bilvalvia spat was determined by purposive sampling, which consisted of 2 (two) subzones and each subzone is located in the intertidal zone, namely at the highest high tide and highest low tide point in the mangrove ecosystem area, namely Subzone 1 is located in the lower subzone (Upper) in the highest tide area. Subzone 2 is located in the Upper (Lower) subzone at the lowest ebb and is on the beach. The distance between subzones is 50 meters.
The results showed that the distribution of the abundance and spat length of
A. granosa bivalves in the natural and rehabilitation mangrove ecosystems on Rangsang Island differed each month (November, December and January). The highest average abundance and length were found in December in rehabilitation mangroves of 79100 ind/100 m2 and 7.67 (±3.94) mm in length and in natural mangroves of 107100 ind/100 m2 and 4.25 (±3.60) in length and with an average mangrove density of 2,283.33 ind/ha and 42,33.33 ind/ha. The species found in the rehabilitated and natural mangrove ecosystems consist of Avicennia alba and Avicennia marina. Comparison of the abundance of Bivalve spats between the rehabilitation mangroves and natural mangroves did not show significant differences either between time periods or between zones. Spat length of A. granosa bivalves was affected (strong category) by pH and temperature. The relationship between mangrove density and A. granosa abundance was in the very strong category in December 2020 and January 2021, while the relationship between mangrove density and A. granosa abundance in November 2020 was in the strong category.
The condition factor results showed that Bivalvia A. granosa in the rehabilitation mangrove ecosystem ranged from -5.41 to -1.34 and in natural mangrove ecosystems it ranged from -1.90 to -1.4. From these results the analysis of condition factors in both ecosystems described environmental conditions that were not good enough for A. granosa. So if viewed from these results, the rehabilitation and natural mangrove ecosystem on Rangsang Riau Island is a habitat that is not good for A. granosa to grow.
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- MT - Fisheries [2946]