HABITAT SUITABILITY MAPPING FOR DIFFERENT CULTURE SYSTEMS OF SEAWEED ALONG THE ENTIRE COASTAL AND MARINE TERRITORY OF BANGLADESH: GENERALIZED ADDITIVE MODELLING FOR SPATIAL PREDICTION

Abstract

Seaweeds are shallow-water, photosynthetic marine macroalgae that have economic value in the food, cosmetics, pharmaceutical, and biofuel/bioplastics industries as well as play a significant ecological role in providing food and habitat for organisms. Although seaweed cultivation is well-advanced in many Asian nations, Bangladesh's seaweed sector is still in its infancy due to multi-dimensional technological, social, and environmental challenges, including a lack of a site suitability map along its entire coastal and marine territorial area. Therefore, we used the Generalized Additive Model (GAM) to develop habitat suitability mapping for different farming systems of seaweeds by using the in-situ production data and associated environmental factors of 180 culture plots of four species (Gracilaria sp., Enteromorpha intestinalis, Ulva lactuca, and Hypnea musciformis) at five culture sites. Besides in situ measurement data, satellite observations and model simulations were also used to gather the necessary data. The GAM analysis revealed that seven explanatory variables jointly explained 78%, 76%, and 79% of the variability in seaweed data from off-bottom long-line, off-bottom net, and floating long-line culture systems, respectively. The model also discovered that TSS is the primary driver for the off-bottom net culture systems and floating long-line system, while salinity is the major driver for the off bottom long-line culture system. The predicted habitat suitability mapping displayed that the predicted suitable areas (50-100%) for floating long-line culture systems are significantly larger (1850 km2 ) than off-bottom long-line and off-bottom net culture systems (380 km2 ). The highly suitable areas (>75% probability) for off-bottom long line and off-bottom net culture systems are restricted to only the southeast coast, more specifically for the sandy bottom areas of the Moheshkhali channel and surrounding areas. The floating long-line culture system is found to be the most suitable for seaweed farming along the entire coast (except Meghna and adjacent estuaries of the central region) of Bangladesh. Since Bangladesh is keen to increase the commercial cultivation of seaweed, this study may provide a crucial tool for achieving the blue economy goal by providing information on habitat suitability maps along the entire coastal and marine territory areas of the country.