Community Structure and Diversity of Benthic Invertebrates during Meteorological Drought in Bueng Sam Roi Yot, Prachuap Khiri Khan Province

Abstract

Study of community structure and diversity change of benthic invertebrates in Bueng Sam Roi Yot, the main wetlands of Khao Sam Roi Yot National Park Wetlands, Prachuap Khiri Khan Province. The wetland was visited every month from October 2022 to October 2023, during which Thailand was affected by a meteorological drought due to El Niño. The accumulated precipitation from October 2022 to May 2023 (dry season) was 0 mm, and from June to October 2023 (wet season) it was 271 mm. The study was carried out at 6 sampling sites across the wetland. Benthic invertebrates were collected using a D- shaped net. The weather data and some physical and chemical water parameters were measured. A total of 24,377 individuals representing 3 phyla, 4 classes, 13 orders, 60 families, and 94 taxa were recorded. Herein, the highest abundance was in Diptera (42.40%), followed by Mesogastropoda (24.47%), and Hemiptera (14.07%). Collembola displayed the lowest abundance (0.01%). The top 3 dominant taxa were chironomids (Order Diptera, Family Chironomidae; 9,789 individuals) , golden apple snails ( Order Mesogastropoda, Pomacea canaliculate; 3,906 individuals), and water bugs (Order Hemiptera, Family Pleidae; 1,449 individuals). Based on the analysis of biological indices, both the Shannon - Wiener diversity index (H') and Simpson's index (D) in the dry season were higher than in the wet season (H’; dry season = 2.03, wet season = 1.47, and D; dry season = 0.84, wet season = 0.68). It was found that benthic invertebrate abundance was highest in January ( 4,110 individuals) . After that, benthic invertebrates tended to decrease and were least found in October 2023 (603 individuals).