**4. Results and discussion**

Twenty-one species of Chlorophyta (**Table 1**) were identified based on the field survey data collected for 2 years: April 2013 to April 2015. These species belonged to 4 orders, 7 families and 11 genera as shown in the cladogram (**Figure 3**). As the Chlorophyta species distribution is tagged with the zonal morphology of the Bet Shankhodhar Reef as a part of this study, it is found that the sampled species can be classified into five major groups as per their zonal or microhabitat occurrences. These five groups are: (i) subtidal and Backreef zone I species, (ii) Backreef zone I species, (iii) Backreef zone I and zone II species, (iv) ubiquitous species and (v) chance factor species. The taxonomic details of the species classified under these five major groups are mentioned below.


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

**3.2. Field data analysis**

**4. Results and discussion**

groups are mentioned below.

family.

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

Twenty-one species of Chlorophyta (**Table 1**) were identified based on the field survey data collected for 2 years: April 2013 to April 2015. These species belonged to 4 orders, 7 families and 11 genera as shown in the cladogram (**Figure 3**). As the Chlorophyta species distribution is tagged with the zonal morphology of the Bet Shankhodhar Reef as a part of this study, it is found that the sampled species can be classified into five major groups as per their zonal or microhabitat occurrences. These five groups are: (i) subtidal and Backreef zone I species, (ii) Backreef zone I species, (iii) Backreef zone I and zone II species, (iv) ubiquitous species and (v) chance factor species. The taxonomic details of the species classified under these five major

**i.** Subtidal and Backreef zone I species: the subtidal and backreef zone I species include four Chlorophyta species from two families: Caulerpaceae and Udoteaceae. *Caulerpa racemosa* v. *occidentalis* (J. Agardh) Børgesen and *Caulerpa scalpelliformis* (Brown ex Turner) C. Agardh var. *denticulata* Børgesen and *Caulerpa taxifolia* (Vahl) C. Agardh belong to the Caulerpaceae family while *Udotea indica* A. & E. Gepp represents the Udoteaceae family.

**ii.** Backreef zone I species: Backreef zone I species include four members from three families: Caulerpaceae, Halimedaceae and Valoniaceae. *Caulerpa sertularioides* (S. Gmelin) Howe *f. brevipes* (J. Agardh) Svedelius represents the Caulerpaceae family while *Halimeda tuna* (Ellis & Solander) Lamouroux belongs to the Halimedaceae family. *Valonia aegagropila* C. Agardh and *Valoniopsis pachynema* (Martens) Børgesen are members of the Valoniaceae

**iii.** Backreef zone I and zone II species: the backreef zone I and zone II species again include four species representing three families: Boodleaceae, Ulvaceae and Valoniaceae. *Boodlea composita* (Harvey) Brand and *Cladophoropsis javanica* (Kützing) P. Silva represent the first family while *Ulva conglobata* Kjellman belongs to the Ulvaceae family. *Valonia utricularis* (Roth) C. Agardh is the other species identified in the backreef zone I and zone II. These four species were found in both the backreef zones from all three sections of Bet

**iv.** Ubiquitous species: Chlorophyta species found in all the three reef zones were considered as ubiquitous species. For Bet Shankhodhar Reef, ubiquitous species included five Chlorophyta species representing three families. *Caulerpa veravalensis* Thivy & Chauhan belonged to Caulerpaceae family while *Chaetomorpha crassa* (C.Agardh) Kützing belonged

Shankhodhar Reef and were absent in the subtidal zone.

genera and species pertaining to different families and genera.

50 Wetlands Management - Assessing Risk and Sustainable Solutions

**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


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 of the species.

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

Reef, four species were found as chance factor species. These species include *Bryopsis pennata* Lamouroux from the Bryopsidaceae family. This species was found in the fore reef zone of the western section of the reef. Two species of *Caulerpaceae*: *Caulerpa racemosa* (Forsskål) J. Agardh and *Caulerpa racemosa* (Forsskål) J. Agardh v. *macrophysa* (Sonder ex Kützing) Taylor were encountered in the subtidal zone of the western section and the backreef zone I of the central section, respectively. The remaining species, *Chaetomorpha linum* (O. F. Müller) Kützing, member of Cladophoraceae family, was also observed for once in the subtidal zone of the western section of the reef.

From the preceding classification of the 21 Chlorophtya species, as per their spatial occurrences on the reef, the following 4 species: *Caulerpa sertularioides*, *Halimeda tuna*, *Valonia aegagropila* and *Valoniopsis pachynema,* are found exclusive to the back reef zone 1 of Bet Shankhodhar Reef.

The establishment of seaweeds or marine macroalgae within a habitat zone involves complex physical interactions as well as biological, ecological and chemical processes at the microscale [25]. These processes include release of propagules by reproductive adults, migration of propagules to suitable substrates, initial adhesion to the substratum surface, permanent attachment and further growth and development [25]. Availability of suitable substrate, light quantity and quality and nutrients are three major abiotic factors that control the settlement and growth of macroalgal communities within an ecosystem [6].

**Figure 4.** Indicator Chlorophyceae species of Backreef zone I of Bet Shankhodhar Reef: Plate A (1A: *Halimeda tuna* species

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**Figure 5.** Indicator Chlorophyceae species of Backreef zone I of Bet Shankhodhar Reef: Plate B (1A: *Valonia aegagropila* species and 1B: *V. aegagropila* in its habitat; 2A: *Valoniopsis pachynema* species and 2B: *V. pachynema* on rocky substratum).

and 1B: *H. tuna* in its habitat; 2A: *Caulerpa sertularioides* species and 2B: *C. sertularioides* in shallow tidal pool).

*Halimeda* is a globally significant, calcifying, green macroalgae genera strongly associated with tropical coral reef habitats [26]. *Halimeda* species are widely distributed across the reefs indicating different reef conditions and are considered important primary producers of the backreef and lagoon habitats [6]. These species prefer moderate energy environments like shallow backreef and lagoon habitats, while in the fore-reef zone, *Halimeda* species may occur in large populations even at greater depths beyond 100 m [26]. Approximately 75% of *Halimeda* species prefer consolidated or gravelly habitats such as against sand or mud substratum [6] and the same was experienced with *H. tuna* at Bet Shankhodhar Reef (**Figure 4**: Plate A: 1A and 1B).

*Caulerpa* is another major Chlorophyta genus, commonly found in the tropical and subtropical coastal waters throughout the world [27]. *Caulerpa* species generally occur in the intertidal and subtidal zones and prefer sandy and rocky reef substrates. They are also important primary producers of the backreef zone and lagoon habitats similar to that of *Halimeda* genera [6]. *C. sertularioides* is rather considered as a secondary metabolite which yields different potentially bioactive compounds, both toxic and non-toxic [27]. This chemically defended species inhabits tropical reefs with high fish populations [27] and prefers unconsolidated sand or soft mud substratum in the shallow tidal pools [28]. In Bet Shankhodhar Reef, this species is found in abundance in the tidal pools (**Figure 4**: Plate A: 2A and 2B) in the backreef zone I along with other *Caulerpa* species.

*Valonia aegagropila* species from the Valoniaceae family was also found in the backreef zone I of Bet Shankhodhar Reef (**Figure 5**: Plate B: 1A and 1B) during the field surveys. This species is identified as a lower mid-littoral zone species, inhabiting shallow tidal pools and prefers Macroalgae Species as Zonal Indicators of Coral Reef: A Case Study from Bet Shankhodhar Reef… http://dx.doi.org/10.5772/intechopen.81640 53

Reef, four species were found as chance factor species. These species include *Bryopsis pennata* Lamouroux from the Bryopsidaceae family. This species was found in the fore reef zone of the western section of the reef. Two species of *Caulerpaceae*: *Caulerpa racemosa* (Forsskål) J. Agardh and *Caulerpa racemosa* (Forsskål) J. Agardh v. *macrophysa* (Sonder ex Kützing) Taylor were encountered in the subtidal zone of the western section and the backreef zone I of the central section, respectively. The remaining species, *Chaetomorpha linum* (O. F. Müller) Kützing, member of Cladophoraceae family, was also observed for

From the preceding classification of the 21 Chlorophtya species, as per their spatial occurrences on the reef, the following 4 species: *Caulerpa sertularioides*, *Halimeda tuna*, *Valonia aegagropila* and *Valoniopsis pachynema,* are found exclusive to the back reef zone 1 of Bet Shankhodhar Reef.

The establishment of seaweeds or marine macroalgae within a habitat zone involves complex physical interactions as well as biological, ecological and chemical processes at the microscale [25]. These processes include release of propagules by reproductive adults, migration of propagules to suitable substrates, initial adhesion to the substratum surface, permanent attachment and further growth and development [25]. Availability of suitable substrate, light quantity and quality and nutrients are three major abiotic factors that control the settlement

*Halimeda* is a globally significant, calcifying, green macroalgae genera strongly associated with tropical coral reef habitats [26]. *Halimeda* species are widely distributed across the reefs indicating different reef conditions and are considered important primary producers of the backreef and lagoon habitats [6]. These species prefer moderate energy environments like shallow backreef and lagoon habitats, while in the fore-reef zone, *Halimeda* species may occur in large populations even at greater depths beyond 100 m [26]. Approximately 75% of *Halimeda* species prefer consolidated or gravelly habitats such as against sand or mud substratum [6] and the same was experienced with *H. tuna* at Bet Shankhodhar Reef (**Figure 4**:

*Caulerpa* is another major Chlorophyta genus, commonly found in the tropical and subtropical coastal waters throughout the world [27]. *Caulerpa* species generally occur in the intertidal and subtidal zones and prefer sandy and rocky reef substrates. They are also important primary producers of the backreef zone and lagoon habitats similar to that of *Halimeda* genera [6]. *C. sertularioides* is rather considered as a secondary metabolite which yields different potentially bioactive compounds, both toxic and non-toxic [27]. This chemically defended species inhabits tropical reefs with high fish populations [27] and prefers unconsolidated sand or soft mud substratum in the shallow tidal pools [28]. In Bet Shankhodhar Reef, this species is found in abundance in the tidal pools (**Figure 4**: Plate A: 2A and 2B) in the backreef zone I along with

*Valonia aegagropila* species from the Valoniaceae family was also found in the backreef zone I of Bet Shankhodhar Reef (**Figure 5**: Plate B: 1A and 1B) during the field surveys. This species is identified as a lower mid-littoral zone species, inhabiting shallow tidal pools and prefers

once in the subtidal zone of the western section of the reef.

52 Wetlands Management - Assessing Risk and Sustainable Solutions

and growth of macroalgal communities within an ecosystem [6].

Plate A: 1A and 1B).

other *Caulerpa* species.

**Figure 4.** Indicator Chlorophyceae species of Backreef zone I of Bet Shankhodhar Reef: Plate A (1A: *Halimeda tuna* species and 1B: *H. tuna* in its habitat; 2A: *Caulerpa sertularioides* species and 2B: *C. sertularioides* in shallow tidal pool).

**Figure 5.** Indicator Chlorophyceae species of Backreef zone I of Bet Shankhodhar Reef: Plate B (1A: *Valonia aegagropila* species and 1B: *V. aegagropila* in its habitat; 2A: *Valoniopsis pachynema* species and 2B: *V. pachynema* on rocky substratum).

intertidal rocks and coralline stones as suitable substratum [10]. Other species from the same genus have been reported from reef front zones of shelf-edge atolls of northwestern Australia [29]. Occurrence of this species is reported from the rocky substratum at the intertidal sampling sites of Uran coast of Navi Mumbai, Maharashtra, India [30].

**Author details**

**References**

Nandini Ray Chaudhury1

\*, Dimpal Sanghvi2

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\*Address all correspondence to: nandinirc@sac.isro.gov.in

1 Space Applications Centre (ISRO), Ahmedabad, India

2 M.G. Science Institute, Ahmedabad, India

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*Valoniopsis pachynema* is another Valoniaceae family member which forms stiff cushions or spongy mats on intertidal rocks of coralline origin [10]. This is a common tropical sea species and prefers hard substratum like intertidal rocks and dead corals. It forms green, hairy clumps and appears as turfs in littoral zones dominated by high wave actions. In our study site, this species was found in the backreef zone I, on the dead reef substrate in association with invasive zootaxa: Z*oanthus* (**Figure 5**: Plate B: 2A and 2B).
