Assessment of trophic change and its probable impact on tropical estuarine environment (the Kodungallur-Azhikode estuary, India)

Abstract

The cumulative effects of global change, including climate change, increased population density and domestic waste disposal, effluent discharges from industrial processes, agriculture and aquaculture will likely continue and increases the process of eutrophication in estuarine environments. Eutrophication is one of the leading causes of degraded water quality, water column hypoxia/anoxia, harmful algal bloom (HAB) and loss of habitat and species diversity in the estuarine environment. The present study attempts to characterize the trophic condition of coastal estuary using a simple tool; trophic index (TRIX) based on a linear combination of the log of four state variables with supplementary index Efficiency Coefficient (Eff. Coeff.) as a discriminating tool. Numerically, the index TRIX is scaled from 0 to10, covering a wide range of trophic conditions from oligotrophic to eutrophic. Study area Kodungallur-Azhikode Estuary (KAE) was comparatively shallow in nature with average depth of 3.6±0.2 m. Dissolve oxygen regime in the water column was ranged from 4.7±1.3 mgL Comparisons over different spatial and temporal scales in the KAE and study observed that, estuary experiencing high productivity by the influence of high degree of eutrophication; an annual average of 6.91 TRIX was noticed in the KAE and seasonal highest was observed during pre monsoon period (7.15) and lowest during post monsoon period (6.51). In the spatial scale station V showed high value 7.37 and comparatively low values in the station VI (6.93) and station VII (6.96) and which indicates eutrophication was predominant in land cover area with comparatively high water residence time. Eff. Coeff. values in the KAE ranges from −2.74 during monsoon period to the lowest of −1.98 in pre monsoon period. Present study revealed that trophic state of the estuary under severe stress and the restriction of autochthonous and allochthonous nutrient loading should be keystone in mitigate from eutrophication process.

A global scientific literature of research on water quality indices: trends, biases and future directions

“…We found that 177 articles were published about water in India, focusing on various topics such as coastal environments (Jayachandran and Nandan, 2012); groundwater (Magesh and Chandrasekar, 2013;Singh et al, 2011) and wastewater reuse (Mojid et al, 2012). Rural and isolated locations in India are beginning to face water scarcity, leading to a high dependence on groundwater for public and agricultural supply (Magesh and Chandrasekar, 2013).…”

Aplikasi Analisis Klaster Dan Indeks Trix Untuk Mengkaji Variabilitas Status Trofik Di Teluk Pegametan, Singaraja, Bali

“…Sebaran stasiun atau titik pengamatan telah mengikuti pola arus yang ada di Teluk Pegametan dan sebagai acuan untuk mengetahui tren status trofik secara spasial. Arus dan arahnya sangat berperan memengaruhi tren variabilitas status trofik di mana kondisi terbaik ketika arus yang tinggi disertai arah yang terkonsentrasi diduga memiliki kualitas airnya lebih baik dibandingkan dengan keadaan arus rendah, serta arahnya yang tidak terkonsentrasi (Jayachandran & Nandan, 2011). Pada dendogram within groups untuk hierarchical cluster analysis mengungkapkan bahwa Teluk Pegametan telah Data kualitas perairan memiliki korelasi erat terhadap status trofik dan sangat memungkinkan untuk dijadikan sebuah indikator penunjuk status trofik (Tsuzuki, 2006).…”

Economic valuation of gillnet fishing in Vembanad Lake, Kerala, South India, using market price approach

“…Several studies that have been carried out in the Vembanad Lake, on species availability and gear-wise catch of major fishes, indicated significant reduction in the fish catch (Shetty, 1965;Kurup, 1982;Kurup and Samuel, 1985a,b;Vijayan et al, 1993;Anon., 2001;Bijoy Nandan, 2007;Harikrishnan et al, 2011;Asha et al, 2014). The reduction in fish availability in Vembanad Lake, could be attributed to various reasons such as overfishing, anthropogenic activities (urban encroachment, harbour development), sand mining, agricultural practices, discharge of effluents from various sources, both point and non-point sources (Jayachandran and Bijoy Nandan, 2012). In addition, Thanneermukkom Barrage dividing the Vembanad into saline (Northern part) and freshwater zone (Southern part) also led to biodiversity loss and reduction in the fish stock, affecting the livelihood of traditional fishers and other ecological services as well.…”