Application of multivariate analysis to determine spatial and temporal changes in water quality after new channel construction in the Chilika Lagoon

• New channel opening during lagoon restoration increased mean salinity level.
• Self-Organizing Map provided comprehensive visualization of water quality data.
• Salinity explained the largest part of variance in the water quality of restored lagoon.
• The pH and pCO2 exhibited pulse-type resilience after the restoration.

Lagoon ecosystems have been severely degraded by anthropogenic activities, which result in ecological and hydrological changes in the system. Detailed understanding of the recovery processes of restored lagoon systems has been impeded by the underlying complexity of integral environmental components. The aim of this study was to understand relationships between water quality variables in a restored lagoon, and temporal and spatial changes at each recovery stage after lagoon restoration. Ten water quality parameters were monitored on a monthly basis at 30 sampling sites in the Chilika Lagoon from 1999 to 2009. Self-Organizing Map and principal component analyses showed that salinity was the dominant factor for the Chilika Lagoon and had maximal component loading in the principal component analysis. Mean salinity level increased after opening of a new mouth in the study site, however, a decreasing trend was observed 4 years after the restoration. The pH and pCO2 exhibited pulse-type resilience after the restoration event. The average nitrate:phosphate ratio increased steadily during the monitoring period. Multivariate analysis of monitoring data of the restoration site provided a deep understanding of its temporal and spatial change. It would be worthwhile to extend multivariate analysis to diverse ecosystems, while considering biological components is recommended in order to evaluate the comprehensive response of the restored system.