Species Diversity of Echinoderms in Manubul Island, Sulu Pro- Vince, Southern Philippines
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Biodiversity Journal, 2021,12 (2): 301–311 https://doi.org/10.31396/Biodiv.Jour.2021.12.2.301.311 Species diversity of Echinoderms in Manubul Island, Sulu Pro- vince, Southern Philippines Shehada I. Tawasil1*, Ranjiv D. Alibon1 & Sophia L. Bensali1 1Department of Biological Sciences, College of Science and Mathematics, Western Mindanao State University, Normal Road, Baliwasan, Zamboanga City 7000, Philippines *Corresponding author, e-mail: [email protected] ABSTRACT Echinoderms, often the most common marine organisms in the intertidal areas, are one of the target organisms in commercial fishing in Sulu Province, Southern Philippines. Proper regula- tion of Echinoderm harvesting requires a baseline data on its species diversity. Thus, we con- ducted a rapid survey of Echinoderms in the intertidal areas of Manubul Island, Sulu Province for three months to assess its species diversity using the Belt Transect Method. We identified 14 Echinoderm species through morphology-based identification with Tripneustes gratilla as the most frequently recorded species, comprising 17.94% of the total sightings. The recorded Echinoderms in Manubul Island is moderately diverse (H’= 2.089), possibly due to habitat het- erogeneity (seagrass, mangrove, and beach ecosystems), and normal water conditions of the island (water temperature, pH, salinity and dissolved oxygen). Although most of the identified Echinoderm species in Manubul Island are common to other areas, the island was found to be a habitat of one data deficient species (Holothuria arenicola) and one endangered species (Holothuria scabra), and this has important implications on effective regulation of Echinoderm harvesting in the island in order to protect and conserve them as well as to attain its sustainable utilization. KEY WORDS Conservation; diversity; Echinoderms; endangered species; management plans. Received 29.10.2020; accepted 28.12.2020; published online 26.04.2021 INTRODUCTION developing new drugs (Walag, del Rosario 2018). To date, there are approximately 7,000 Echinoderm Echinoderms are group of marine organisms species that are distributed worldwide in all depths which play functional roles in the marine ecosys- in the marine ecosystems (Raghunathan, Venkatara- tems by providing essential links between unused man, 2012). The Indo-Pacific region, specifically organic materials in the detritus and larger marine the Philippines, hosts most of the Echinoderms organisms (Hernández et al., 2006), they also serve species in the world (Stöhr et al., 2012). In fact, it as predators to different benthic marine organisms has been identified as a hotspot of sea cucumber (Bos et al., 2008). Moreover, some Echinoderms are fisheries in Asia (Choo, 2008). of economic importance to humans such as sea cu- Philippines is one of the major countries which cumbers, sea urchins, and sea stars, as they are com- exports Echinoderms particularly sea cucumbers monly consumed as food (Llacuna et al., 2016), worldwide (Akamine, 2005). As a result, most of traded as ornaments (Bos et al., 2008), and used for the Echinoderms in the country are threatened by 302 SHEHADA I. TAWASIL ET ALII overfishing especially the sea cucumbers and sea MATERIAL AND METHODS urchins (Toral-Granda et al., 2008) due to its high demand and good global prices in the market Sampling sites and design (Nievales et al., 2006; Purcell et al., 2013). This problem has already been recognized in the country The island of Manubul (5°33’North, through the Bureau of Fisheries and Aquatic Re- 120°48’East), located in the province of Sulu, sources (BFAR) Administrative Order, Circular Southern Philippines, has a total coastal area of Number 248, Series of 2013, which imposed limits 94,377 hectares with 9,437.55 meters shoreline. A and requires permit to those who are engaged in the map of Manubul Island was obtained from the of- Echinoderm fishery particularly sea cucumbers fice of Department of Environment and Natural Re- trading, but the implementation is still a challenge sources-Autonomous Region of Muslim Mindanao up to this date, probably due to the lack of support (DENR-ARMM), Sulu, Philippines (Fig. 1), and from the locals and shortage of funds for enforce- was used as a guide to locate mangrove, sandy and ment (Gamboa et al., 2004). settlement areas within the island. Three barangays Information concerning Echinoderms in the located in this island specifically on its intertidal Philippines remains inadequate and is only limited zones were selected as the sampling sites, namely, to those commercial species, leaving the non-com- North Manubul, Tengah Manubul, and South mercial ones unaccounted (Jontilla et al., 2014). For Manubul. During the preliminary visit in each of instance in the Southern Philippines, only few stud- the sampling site, we randomly collected 100 grams ies related to Echinoderms have been conducted in of soil samples in the intertidal areas of the island, this region of the country, including but not limited and brought in Regional Soils Laboratory-Depart- to the works of Llacuna et al. (2016), Pitogo et al. ment of Agriculture (RSL-DA), Zamboanga City, (2018), Walag et al. (2018), Alibon & Madjos Philippines for the substrate type analysis. (2019), Alibon & Madjos (2020). The first site is situated in the coastline of North Sulu, an island province in the Southern Philip- Manubul (5.4718, 120.7968), a sea grass ecosys- pines, is one of the richest fishing grounds in the tem, characterized by its gently sloping sandy coast country with fishing as its most important industry and mostly dominated with residential houses along (Mamalangkap et al., 2018), but its richness remains on its shores (Fig. 2). The second site is situated in biologically unstudied due to the existing security the coastline of Tengah Manubul (5.4702, threats within the province (Banlaoi 2008; Peleo 120.7960), adjacent in a mangrove ecosystem, char- 2015; United Nation 2019). Although the existing se- acterized by its thick patches of mangroves with curity threats in the province are favourable in free- sandy loam substrate (Fig. 3). Finally, the third site ing the area from overexploitation of the resources, is situated in the coastline of South Manubul the same concern had kept the locals unaware on the (5.4667, 120.7946), a beach ecosystem and charac- current conservation status of the organisms present terized by its loamy sand shores (Fig. 4). The first in the area (Tabugo et al., 2013). One of the benefi- and third sites are the fishing grounds of the local cial fishing grounds in Sulu Province is the island of fishermen in the island where Echinoderms are har- Manubul. The inhabitants of this island are predom- vested. inantly Tausug, a Muslim ethnic group currently liv- Sampling was done for three months (June to ing in Sulu Archipelago (Frake, 2006), who maintain August, 2018). The species diversity of Echino- a subsistence economy based on fishing, with Echin- derms was assessed using the Belt Transect oderms as one of the target organisms in commercial Method. In each of the three selected sampling fishing. However, if Echinoderm harvesting contin- sites, a 315 meters baseline was measured from ues unregulated in the island, this could also increase the shoreline with a depth range of 1 to 10 meters, the chances of overharvesting in the long run. Thus, then three belt transects measuring 100 meters in this study was conducted to assess the status of length and five meters in width were established Echinoderm diversity in Manubul Island, in order to perpendicular to the baseline with 150 meters in- support conservation and management plans as well terval between each transe ct, having a total of nine as to attain its sustainable utilization in Sulu surveyed transects in all sampling sites in province, Southern Philippines. Manubul Island. Species diversity of Echinoderms in Manubul Island, Sulu Province, Southern Philippines 303 Figures 1-4. Map of Manubul Island, Sulu Province, Southern Philippines (Fig. 1) and the actual sites of North Manubul (Fig. 2), Tengah Manubul (Fig. 3) and South Manubul (Fig. 4). Collection, preservation and identification of ble taxon through morphology-based identifica- the samples tion and using a standard key reference (Schoppe, 2000; Purcell et al., 2012), subsequently the ini- Direct counting of samples was done through tially identified species were further validated with wading and snorkelling within each transect of the the help of an expert and were arranged systemat- three sampling sites. One to two representatives of ically. each specimen were collected and were carefully washed with seawater to remove silt and debris. Evaluation of the conservation status The collected samples were stored out, transferred to properly labelled containers with 10% formalin The identified Echinoderms species were fur- and preserved in 70% ethanol for permanent stor- ther evaluated in terms of its conservation status age. Well focused and correctly exposed close-up based on the data provided by the International and whole morphological features of the speci- Union for Conservation of Nature (IUCN) Red mens were photographed in situ using ILCE List of Threatened Species or also known as the SONY α3000 20.1 Megapixel. The collected and IUCN Red List. The IUCN Red List is widely rec- preserved samples were deposited in the labora- ognized as the most comprehensive global ap- tory of Department of Biological Sciences, Col- proach in evaluating the conservation status of lege of Science and Mathematics, Western biological species. It uses a set of categories to Mindanao State University for further identifica- evaluate the extinction risk of the species which tion. Samples were identified to the lowest possi- include Not Evaluated, Data Deficient, Least Con- 304 SHEHADA I. TAWASIL ET ALII cern, Near Threatened, Vulnerable, Endangered, quently recorded species, comprising the 17.94% Critically Endangered, Extinct in the Wild, and of the total sightings, followed by Echinothrix di- Extinct. adema (17.89%), Ophiocoma scolopendrina (16.18%), and Echinometra mathaei (16.07%) (Fig. Measurement of physico-chemical parameters 5).