**3. Field data collection and analysis**

The coral reefs in Gulf of Kachchh are predominantly patchy structures built up on wave-cut sandstone banks [16] on the southern shore of the gulf along with 34 adjoining islands [17]. These coral reefs are mainly comprised of fringing structure with all sub-types (i.e., platform, patch and coral pinnacles; [13]) restricted to a vast intertidal region [18]. Gulf of Kachchh coral reefs are adapted to extreme environmental conditions: high temperature ranges (10–35°C), high salinity ranges (25–40 ppt), large tidal ranges, strong tidal currents and heavy sediment loads [19]. As a result of isolation and above-mentioned extreme environmental conditions, the species diversity of corals in this region is low [20]. The coral reefs of Gulf of Kachchh are under International Union for Conservation of Nature (IUCN) Category I Marine Protected Area (MPA). Gulf of Kachchh Marine Sanctuary and Marine National Park were established in 1980 and 1982, respectively [21]. The present study was carried out in the coral reef area adjacent to Bet Shankhodhar Island (**Figure 1B** and **C**) situated to the east of Okhamandal area on the mainland coast and 2 km away from the Okha Port. The island owes its name Bet Shankhodhar to its unique shape resembling that of a conch shell [22]. Bet Shankhodhar Island has a fringing reef area (**Figure 1C**) of 28 hectares to its north [22] adjacent to a narrow strip of beach with significant exposures of beach rock [23]. This reef was selected for the present case study for its reported diversity of 120 species of macroalgae [22]. The study site on Bet Shankhodhar Reef is located within the coordinates of 22°28′36" N–22°28′52" N latitudes and 68°08′14″ E–69°08′40″ E

was further divided into three micro-zones in the north-south direction based on their topographical and geomorphological characteristics and level of tidal inundation. These three

**Figure 2.** Microhabitat zones of Bet Shankhodhar Reef. (A) Exposure of subtidal zone, (B) Backreef zone I and (C) Backreef

(**Figure 1D**). The survey area of the reef

longitudes and covered a survey area of 0.35 km2

48 Wetlands Management - Assessing Risk and Sustainable Solutions

zone II.

#### **3.1. Field sampling of seaweeds/macroalgae**

The study area of Bet Shankhodhar Reef was divided into three sections in the west-east direction, as: (i) western, (ii) central and (iii) eastern sections (**Figure 1D**) for systematic field sampling and equal representation of the reef habitat. Seaweed sampling was routinely carried out for 2 years: from April 2013 to April 2015 with sampling exercise coinciding with the annual cycles of seaweed abundance and growth, that is, local seasons of post-monsoon (October-November), winter (December-February), spring (March) and summer (April-June), respectively. Field surveys/samplings were carried out during low-tide exposures of the reef following line intercept transects (LITs). For quantitative assessment of the seaweeds in the given area, the GPS-tagged, LITs were laid perpendicular to the coast in a seaward direction with the help of a 50-m-long rope [24]. The length of the transect essentially depended on the tidal exposure of the reef during the field surveys. The minimum and maximum transect lengths surveyed were 52 and 372.5 m, respectively. The maximum depth of the subtidal zone sampled for the present study is 1 m. Quadrats of 1 m2 were positioned over the transects for quantitative seaweed sampling wherever macroalgal growth, density and diversity were visibly high. A total of 182 GPS-tagged quadrats was sampled for the seaweeds over a total of 23 transects on the reef site.

**Figure 3.** Cladogram of Chlorophyta species sampled from Bet Shankhodhar Reef.

### **3.2. Field data analysis**

Macroalgae samples collected from the field were taken to laboratory for herbarium preparation and sample identification. Morphological criteria and reproductive structures of the algae specimens were analysed for taxa identification. A cladogram (**Figure 3**) was prepared for the sampled Chlorophyta in order to generate classification statistics, that is, number of genera and species pertaining to different families and genera.

to Cladophoraceae family. The other three species: *Enteromorpha compressa* (Linnaeus) Nees, *Ulva fasciata* Delile and *Ulva lactuca* Linnaeus are members of the Ulvaceae family.

Macroalgae Species as Zonal Indicators of Coral Reef: A Case Study from Bet Shankhodhar Reef…

**Months**

1 *Boodlea composita* (Harvey) Brand × × √ √ √ × × × × 2 *Bryopsis pennata* Lamouroux × × × √ × × × × × 3 *Caulerpa racemosa* (Forsskål) J. Agardh × × × × × √ × × ×

 *Caulerpa taxifolia* (Vahl) C. Agardh × × √ √ √ √ √ × × *Caulerpa veravalensis* Thivy & Chauhan √ × √ √ × × × × × *Chaetomorpha crassa* (C. Agardh) Kützing × × × √ √ √ √ × × *Chaetomorpha linum*(O. F. Müller) Kützing × × × × × √ × × × *Cladophoropsis javanica* (Kützing) P. Silva × × × × √ √ √ × × *Enteromorpha compressa* (Linnaeus) Nees × × √ √ √ √ × × × *Halimeda tuna* (Ellis & Solander) Lamouroux √ × × × × × √ × × *Udotea indica* A. & E. Gepp. × × × × √ × √ × √ *Ulva conglobata* Kjellman × × √ √ × × × × × *Ulva fasciata* Delile × × × × √ √ √ × × *Ulva lactuca* Linnaeus × × √ √ √ √ √ × × *Valonia aegagropila* C. Agardh × × √ × √ × × × × *Valonia utricularis* (Roth) C. Agardh × × √ √ × × √ × × *Valoniopsis pachynema* (Martens) Børgesen × × √ √ × × × × × The calendar months are denoted with the first letter, for example, O = October, starting with October and continuing up to June indicating local post-monsoon, winter, spring and summer seasons; √ denotes presence and x denotes absence

**Table 1.** Chlorophyta species observed during different months at Bet Shankhodhar Reef.

**O N D J F M A M J**

http://dx.doi.org/10.5772/intechopen.81640

51

× × × √ × × × × ×

× × √ √ √ × √ × ×

× × × × × √ √ × ×

× × √ √ √ × × × ×

**v.** Chance factor species: the Chlorophyta species encountered only once during the twoyear field sampling are considered as chance factor species. In the case of Bet Shankhodhar

**Sr. No. Chlorophyta species Field site: Bet Shankhodhar Reef**

4 *Caulerpa racemosa* (Forsskål) J. Agardh

6 *Caulerpa scalpelliformis* (Brown ex Turner) C. Agardh var. *denticulata* Børgesen

Howe *f. brevipes* (J. Agardh) Svedelius

5 *Caulerpa racemosa v. occidentalis* (J. Agardh) Børgesen

7 *Caulerpa sertularioides* (S. Gmelin)

of the species.

*V. macrophysa* (Sonder ex Kützing) Taylor
