Construction of Groyne at Vembar Village, Vilathikulam Thaluk
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Construction of groyne at Vembar Village, Vilathikulam Thaluk, Tuticorin Village – Baseline data on the marine biodiversity and Impacts on the marine biodiversity in Gulf of Mannar 1. BACKGROUND The Gulf of Mannar along the Indian coast is situated between Lat. 8° 47’ - 9° 15’ N and Long.78° 12’ - 79° 14’ E. Coral reefs are distributed on the shelfs of 21 islands, lying between Rameswaram and Kanyakumari. The Gulf of Mannar is one of the Marine Biosphere Reserves (GOMMBRE) covering an area of 10,500 sq. km. The Gulf of Mannar is one of the biologically richest and important habitats for sea algae, seagrass, coral reef, pearl banks, sacred chank bed, fin and shell fish resources, mangroves so also endemic and endangered species. The islands occur at an average distance of 8-10 km from the mainland. The 21 islands and the surrounding shallow water area covering 560 km2 were declared as Marine National Park. Coral reef area covered about 110 km2 and coral reef status during 2005 showed that about 32 km2 of reef area had already been degraded, mainly due to coral mining and destructive fishing practices. Coral diversity of Gulf of Mannar harbored 117 species and seagrass comprised 13 species. Along with corals, luxuriant and patch seagrass meadows in Gulf of Mannar provide high biodiversity. Vembar group of Islands namely Upputhanni, Puluvinichalli and Nallathanni Island these coral habitat islands located little far from the Groins sites in Vembar coast. Three proposed groynes will be constructed near inshore area of Vembar coast of Tuticorin district, by PWD / WRO. Project area is located about 11 km away from Gulf of Mannar Marine National Park boundary line but groynes sites are coming under the Marine biosphere reserve area. There are no coral reef islands located closer proximity of groynes site. Coral reef Island of Upputhanni Island (Vembar group) is located about 13 Km from the groynes site and about 17 km away from Kariyachalli Island (Tuticorin group). Under this project, PWD / WRO has proposed to construct three different length groynes (Groyne – 1 (500m), Groyne – 2 (200m) and Groyne – 3 [170m]). The three groynes will be covering a shore distance of 820 meter. Thus, the baseline data on the biodiversity in particular coral reef and seagrass meadows is very much essential to find out the diversity of resources and distribution pattern in the nearby 1 project location. Hence, the present assessment was carried out to collect data on the diversity, distribution and abundance of marine biodiversity including ecologically sensitive habitats (corals and seagrass beds) and fish population in the study area within 10 km radius from groins site were assessed. Benthic assessment was carried out within the 10km radius from the groyne sites and a total of nine zones were fixed with each zone covering an distance of 1Km. Zones were further divided into equal spaced grids (G) of approximately 1 sq km each and totally 137 numbers of grids formed with in the 10 km radius. Zone 1 is located nearer to the groynes point which consist of G1 to G18; Zone 2 (G19 to G36); Zone 3 (G37 to G54); Zone 4 (G55 to G72); Zone 5 (G73 to G89); Zone 6 (G90 to G104); Zone 7 (G105 to G118) ; Zone 8 (G119 to G129), Zone 8 (G130 to G137) which was away from the groynes. Fig. 1: Map showing the monitoring location in Vembar Coast 2 2. Methodology The survey started with mapping of the proposed area, using manta tow technique (Done et al., 1982) in inside 10 km radius area. The assessment involved SCUBA diving. Coral reef habitat sites were estimated by using the Line Intercept Transect (LIT) followed by standard monitoring protocol (English et al., 1997). Four to six line intercept transect (20 meter) were laid on the benthic forms to assess the coral, algae, other fauna and abiotic percentage cover in the each grid. Coral recruitment density and coral health issues prevalence were assessed along the transect line. Seagrass meadows were assessed by using 0.5 X 0.5 m2 quadrats (Saito and Atobe, 1970) and seagrass cover and shoot density field data were collected from the grids. Quadrat number varies according to the availability of seagrass resources. The macro faunal communities were assessed using 1 X 1 m2 quadrats following the method of English et al., (1997). Fish abundance and diversity was assessed using belt transect method (English et al. 1997). Length of each transect was 50 m and each transect was separated by 50 m gap. All the fishes encountered within 2.5 meters on both side. The mean seagrass cover and coral cover were calculated only for the observed grids respectively. The present rapid assessment was carried out between 25th March 2017 and 15th April 2017. Coordinates of each grid are given below Zone - 1 Grid No. Latitude Longitude 1 9° 1'30.66"N 78°18'23.02"E 2 9° 1'49.49"N 78°18'51.14"E 3 9° 2'9.06"N 78°19'18.46"E 4 9° 2'32.36"N 78°19'47.17"E 5 9° 2'50.97"N 78°20'16.06"E 6 9° 3'12.59"N 78°20'44.38"E 7 9° 3'32.96"N 78°21'12.70"E 8 9° 3'54.22"N 78°21'36.90"E 3 9 9° 4'19.80"N 78°22'1.29"E 10 9° 4'36.00"N 78°22'26.15"E 11 9° 4'58.82"N 78°22'55.96"E 12 9° 5'17.54"N 78°23'25.17"E 13 9° 5'37.12"N 78°23'46.68"E 14 9° 5'58.77"N 78°24'15.94"E 15 9° 6'13.49"N 78°24'39.72"E 16 9° 6'29.29"N 78°25'9.02"E 17 9° 6'42.39"N 78°25'40.34"E 18 9° 6'59.18"N 78°26'11.28"E Zone – 2 Grid No. Latitude Longitude 19 9° 6'42.61"N 78°26'19.52"E 20 9° 6'17.83"N 78°25'49.06"E 21 9° 6'5.10"N 78°25'19.97"E 22 9° 5'48.58"N 78°24'55.16"E 23 9° 5'31.22"N 78°24'30.05"E 24 9° 5'9.30"N 78°24'9.26"E 25 9° 4'48.21"N 78°23'39.61"E 26 9° 4'32.62"N 78°23'14.52"E 27 9° 4'9.12"N 78°22'45.31"E 28 9° 3'47.73"N 78°22'19.64"E 29 9° 3'29.24"N 78°21'55.67"E 30 9° 3'10.44"N 78°21'27.60"E 31 9° 2'49.56"N 78°21'0.84"E 32 9° 2'28.66"N 78°20'34.36"E 33 9° 2'9.53"N 78°20'8.40"E 34 9° 1'48.72"N 78°19'40.65"E 35 9° 1'30.41"N 78°19'13.14"E 36 9° 1'10.59"N 78°18'45.44"E 4 Zone – 3 Grid No. Latitude Longitude 37 9° 0'55.94"N 78°19'10.92"E 38 9° 1'12.06"N 78°19'34.90"E 39 9° 1'31.17"N 78°20'2.00"E 40 9° 1'51.98"N 78°20'28.25"E 41 9° 2'8.68"N 78°20'54.28"E 42 9° 2'29.55"N 78°21'21.74"E 43 9° 2'48.63"N 78°21'49.90"E 44 9° 3'8.52"N 78°22'16.37"E 45 9° 3'30.27"N 78°22'41.05"E 46 9° 3'49.41"N 78°23'7.23"E 47 9° 4'10.56"N 78°23'35.80"E 48 9° 4'26.24"N 78°24'2.12"E 49 9° 4'47.91"N 78°24'26.78"E 50 9° 5'1.37"N 78°24'50.63"E 51 9° 5'23.39"N 78°25'11.51"E 52 9° 5'40.21"N 78°25'37.17"E 53 9° 6'1.39"N 78°26'4.35"E 54 9° 6'18.15"N 78°26'28.21"E Zone – 4 Grid No. Latitude Longitude 55 9° 5'52.66"N 78°26'40.30"E 56 9° 5'36.66"N 78°26'17.60"E 57 9° 5'17.67"N 78°25'52.85"E 58 9° 4'58.22"N 78°25'29.59"E 59 9° 4'42.73"N 78°25'9.86"E 60 9° 4'23.48"N 78°24'46.51"E 61 9° 4'2.88"N 78°24'18.72"E 62 9° 3'44.10"N 78°23'54.25"E 5 63 9° 3'19.53"N 78°23'26.29"E 64 9° 2'58.82"N 78°23'2.46"E 65 9° 2'43.21"N 78°22'37.53"E 66 9° 2'22.43"N 78°22'10.44"E 67 9° 2'4.15"N 78°21'43.63"E 68 9° 1'43.64"N 78°21'19.62"E 69 9° 1'22.65"N 78°20'54.36"E 70 9° 1'2.66"N 78°20'27.38"E 71 9° 0'44.25"N 78°20'4.47"E 72 9° 0'32.86"N 78°19'45.84"E Zone - 5 Grid No.