STUDY ON THE EFFECT OF SEA CURRENT TO THE CORAL REEF LIFE FORM (SCLERACTINIA)

• Main Author: Kesuma, Addiena
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/80128
• Institution: Institut Teknologi Bandung

Coral reef ecosystems exhibit complex responses to the dynamic nature of their aquatic environment. Variations in these environmental factors contribute to diverse patterns of coral distribution in different locations within each ecosystem. Sea currents, a key physical parameter of water bodies, play a crucial role in the morphological processes and formation of coral reef frameworks. The movement of sea currents around corals determines the orientation and form of coral growth, influencing the structure of coral communities at a local scale. Variations in current velocity at each location can indicate the dominance of different forms of coral growth. This research aims to examine the average velocity of sea currents, the percentage cover and condition of coral reef ecosystems, the dominant coral life forms, and the relationship between groups of coral reef life forms and the ocean current velocities that influence them in Indonesian waters. Data on the average velocity and direction of sea currents were measured using the current real-time global forecasting of sea current data sourced from numerical models, obtained from the Copernicus Marine Environment Monitoring Service (CMEMS). The sea current velocity values are calculated based on the seasonal average velocity and annual average velocity for each observation site. The calculated average velocity is then visualized in the form of a map plot showing the direction and velocity of sea currents. The collection of data on the coral reef ecosystem was obtained from the results of field observations, namely in the form of percent cover and distribution of hard coral biota, obtained from FDC-IPB and WCS-IP. Coral data were collected at different times, between 2009 and 2021, at seven different observation stations, including the waters of Biak Numfor, Kei Besar Island, Mare Island, Pramuka Island and its surroundings, Sabu Island, Sebesi and Sebuku Islands, and Ujung Kulon. The evaluation of diversity and habitat potential adopts an approach that utilizes the morphology or life form classification of hard corals. This classification is implemented through a ternary triangle diagram, specifically an r-K-S ternary diagram. Subsequently, the conservation class is determined based on the percentage distribution of each hard coral life form group (ruderals (r) + competitors (K) + stress tolerators (S) = 100%). The interplay between sea current velocities (u and v components) and the life form of coral reefs is examined through multivariate analysis, specifically canonical correspondence analysis (CCA). Additionally, the statistical relationship between ocean currents and coral life form is explored using Spearman corellation, aiming to ascertain the strength and direction of the linear relationship between these two quantitative variables. The research findings indicate the average total current velocity (magnitude) at the observation sites are in the Sebesi and Sebuku Islands 0,348 m/s, Sabu Island 0,311 m/s, Biak Numfor 0,281 m/s, Pramuka Island and its surroundings 0,269 m/s, Ujung Kulon 0,268 m/s, Kei Besar Island 0,159 m/s, and Mare Island 0,103 m/s. The condition of the coral reef ecosystems that are classified as 'moderate' and are also traversed by 'moderate' sea currents are located at: Biak Numfor, Pramuka Island and its surroundings, Sabu Island, Sebesi and Sebuku Islands, and Ujung Kulon observation site. Kei Besar Island and Mare Island with weak current velocities have coral reef ecosystems in the 'good' category. Observation results from seven observation sites show that there are a total of 13 types of hard coral life forms (scleractinia), with the highest variation found on Mare Island which includes 13 life forms, followed by Kei Besar Island with 12 life forms, and other sites recorded variations in life forms that vary between 9 to 11 forms. The ruderal (r) life form group is positively correlated (? 0,5) with weak currents (0,1-0,2 m/s). The Competitor (K) and Stress-tolerator (S) coral life form groups have a positive correlation (? 0,5) with moderate currents (0,2-0,4 m/s).