Shrimp aquaculture, soil degradation, and climate resilience: A comparative analysis of the Southwestern Coast of Bangladesh

Coastal brackish-water shrimp aquaculture has rapidly transformed land use across the low-lying deltaic coastlines of southwestern Bangladesh, yet its impacts on soil physicochemical properties remain insufficiently quantified at the site scale. This study evaluated soil degradation and climate resilience implications by comparing surface soils (0-15 cm) from 30 sites (15 shrimp-cultured and 15 non-shrimp agricultural sites) across two unions of Shyamnagar Upazila, adjacent to the Sundarbans. Soil texture, bulk density (BD), pH, electrical conductivity (EC), soil organic carbon (SOC), and total nitrogen (TN) were analyzed at the Soil Science Laboratory of Patuakhali Science and Technology University using standardized methods. Data were statistically analyzed in R Studio using one-way ANOVA with Tukey’s HSD, Pearson correlation, simple bivariate linear regression, and principal component analysis (PCA). Significant differences (p < 0.0001, except for Total Nitrogen, p = 0.001) were observed across all soil parameters between land-use types. Shrimp-cultivated soils showed elevated EC (3.56 dS m⁻¹), alkaline pH (7.01), and SOC (4.95%), alongside reduced BD (1.08 g cm⁻³) and markedly lower TN (0.045%) relative to non-shrimp soils. Soil texture differed between land-use types, from silty loam in non-shrimp areas to silty clay loam under shrimp farming, a pattern consistent with prolonged waterlogging and saline intrusion. Principal Component Analysis (PCA) demonstrated clear multivariate differentiation between shrimp and non-shrimp soils, with the first principal component (PC1) consistently explaining 76.2% of the total variance across all analyses. Collectively, non-shrimp soils were characterized by greater compaction and nitrogen depletion, whereas shrimp soils were primarily affected by salinity and pH stress; together, salinization, nitrogen depletion, altered texture, and declining bulk density indicate a salinity-driven land-use lock-in that undermines agricultural productivity and coastal resilience. These findings provide field-based evidence supporting SDGs 2, 13, 14, and 15 for sustainable coastal land management.