Poor hydrological connectivity may be undermining mangrove restoration efforts at the Keta Lagoon Complex Ramsar Site (KLCRS), with a KNUST study identifying dissolved oxygen and pH as key indicators for determining whether sites are suitable for restoration.

The study found that the poorly performing replanted site recorded significantly lower dissolved oxygen and pH levels than natural, degraded and successfully replanted mangrove stands. Dissolved oxygen and pH emerged as the main indicators distinguishing restoration conditions, accounting for 72.5% of the variation along the biological vitality axis.

Researchers found dissolved oxygen at the poorly performing Fiaxor site at 1.1 mg/L, below the 1.5–2.0 mg/L threshold cited for mangrove root respiration. The findings suggest that these water quality differences are signs of compromised hydrological connectivity rather than independent causes of restoration failure.

The researchers therefore identify restoring internal hydrological connectivity as the primary intervention, arguing that improved tidal circulation should naturally improve water quality.

They propose pre-planting screening thresholds of dissolved oxygen of at least 2.0 mg/L, pH of at least 7.5 and salinity of 10–25 ppt to help determine whether sites are suitable for mangrove planting.

The 2026 study, led by Dr Benjamin A. Gyampoh of the Department of Fisheries and Watershed Management, College of Agriculture and Natural Resources (CANR), KNUST, assessed water quality at four sites representing natural, degraded, successfully replanted and poorly performing replanted mangrove stands.

Eleven sampling points were assessed at each site, producing 44 observations covering dissolved oxygen, pH, temperature, salinity, electrical conductivity and total dissolved solids.

The researchers recommend that water quality assessments be conducted before planting using a calibrated multiparameter probe during dry-season ebb tides. They also recommend suspending replanting at poorly performing sites until hydrological rehabilitation has been undertaken and matching mangrove species to sites based on salinity conditions.

The study, “Dissolved oxygen and pH as hydrological connectivity indicators for mangrove restoration site assessment: Evidence from a tidally attenuated Ramsar lagoon in Ghana,” was published in Ecohydrology & Hydrobiology.