Factors Affecting Population Density and Mound Distribution of Mud Lobsters, Thalassina spp.

Abstract

This study is the first to investigate factors affecting population density and mound distribution of mud lobsters, Thalassina spp., in Southern Thailand. Mud lobsters are essential for nutrient cycling and maintaining mangrove ecosystems through their bioturbation activities. This study was conducted by establishing three transect lines in a 5×350 m2area beginning 100 m from the edge of the river towards inland and composed of six subplots with 50-m intervals (i.e., 100, 150, 200, 250, 300, and 350-m subplots). Numbers of mounds were recorded, and mound height and diameter basal area in each subplot were measured. Soil samples were collected, and moisture, grain size distribution, and pH were measured. The results showed that soil grain size was mostly less than 250 μm with an average soil pH of 4.48. The mound density and mound height increased with increased distance from the river (i.e., 267 mounds per hectare at 100 m increased to 1,734 mounds per hectare at 350 m from the river edge) and with decreased soil moisture (72.6% to 65.9%). This indicated that the mud lobsters preferred to build more and higher mounds farther away from the river edge, where they were less affected by the tide and the soil was drier. Findings also indicated that mud lobsters used resource partitioning to reduce intraspecific competition. This study is the first to show that mounds associated with prop roots had greater heights than mounds without prop roots nearby. Doi: 10.28991/ESJ-2024-08-01-012 Full Text: PDF