Stress markers response in clam Ruditapes philippinarum after exposure to sediment liming

Beach sands may harbor human pathogens and antibiotic resistance genes, prompting the 15 proposal of low-dose quicklime (CaO; 1–3% w/w) as a remediation strategy to improve 16 microbiological quality in highly contaminated areas. After application, CaO is converted 17 into calcium carbonate (CaCO3), yet the ecological effects of this residual compound on 18 benthic fauna remain poorly understood. This study evaluated the short-term impact of 19 CaCO3-enriched sediment (3% w/w) on the Manila clam Ruditapes philippinarum under 20 controlled mesocosm conditions. Adult clams were exposed for one week, and survival, 21 burrowing behavior, feeding- and metabolism-related parameters (clearance, ingestion, 22 absorption efficiency and rate, ammonia excretion), and oxidative stress (malondialde-23 hyde, MDA) were assessed using a hierarchical design with tank as the experimental unit. 24 No significant differences were detected between control and CaCO3-enriched treatments 25 for any measured endpoint. Survival remained high, functional responses showed over-26 lapping ranges, and MDA levels did not differ significantly between groups. Although 27 limited to short-term exposure and a single concentration, these findings suggest that re-28 sidual CaCO3 derived from quicklime application did not induce detectable adverse ef-29 fects in adult R. philippinarum under the tested conditions. Further long-term and multi-30 species studies are needed to confirm ecological safety.