Pune: A recent study conducted by the Zoological Survey of India (ZSI) in Pune has shed light on the alarming effects of erosion on the renowned Olive Ridley turtle nesting grounds at the Gahirmatha Marine Wildlife Sanctuary in Odisha. Over the past three decades, the nesting site has migrated an astonishing 14 kilometers northward due to the combined forces of climate change and human activities, according to the findings published in the prestigious scientific journal Marine Pollution Bulletin by Elsevier.
The peer-reviewed study, which enlisted the collaboration of researchers from the Federal University of Pernambuco-Brazil and Federal University of Paraíba-Brazil, meticulously analyzed shoreline transformations from 1990 to 2022 utilizing satellite imagery and advanced digital shoreline analysis system software. Encompassing 929 transects across four distinct zones within the nesting habitat, the research paints a troubling picture for the future of Olive Ridley Arribada, the mass nesting phenomenon recently observed at Gahirmatha.
Dr. Basudev Tripathy, a scientist at ZSI-Pune and one of the authors of the study, expressed deep concern over the findings, emphasizing the implications for the nesting habits of the Olive Ridley turtles. “The marine sanctuary hosts one of the world’s largest congregations of these endangered marine reptiles,” Dr. Tripathy remarked. “However, rampant erosion has drastically reshaped the coastline, compelling the turtles to relocate their nesting grounds northward by 14 kilometers, from the mainland to an adjacent island, where space is now scarce.”
The consequences of this migration are dire, as overcrowding and egg loss loom as imminent threats. Dr. Tripathy elucidated, “The turtles are constrained to lay eggs in a confined space, unable to accommodate their burgeoning numbers. This overcrowding scenario can result in substantial egg loss, with newly arriving turtles often disturbing previously established nests due to the lack of available space. Consequently, many eggs within these disturbed nests may be crushed or exposed, rendering them nonviable.”
The study’s analysis focused on the coastal stretch extending from the Mahanadi river mouth in the south to Dhamra port in the north, dividing it into four zones based on natural landmarks and anthropogenic features. Zone III, encompassing erosion-prone Pentha and Satabhaya Sea beaches, emerged as the most vulnerable segment, experiencing severe coastal erosion despite mitigation efforts. Historically, this zone was a prime nesting site for Olive Ridley turtles, but the relentless erosion has forced the nesting site further north.
The findings revealed that Zone III suffered the most significant erosion, with 89.2% of transects exhibiting such trends. The mean shoreline change rate for the entire study period (1990-2022) was estimated at half a centimeter per year. Notably, periods of heightened erosion coincided with declines in mass nesting events, such as the 50% decrease observed in 2021.
The study identified a myriad of natural and human-induced factors contributing to coastal erosion along the Odisha coast, particularly within the Gahirmatha marine wildlife sanctuary region. Natural causes, including severe floods, cyclonic events, storm surges, and heavy monsoonal rainfall, were cited alongside human interventions such as coastal modifications, exacerbating erosion rates.
Dr. Tripathy underscored the importance of adopting a holistic approach to conservation efforts, taking into account the interconnectedness of ecosystems and the ripple effects of adjacent developmental activities. “While Gahirmatha marine wildlife sanctuary enjoys protection status, nearby coastal interventions can indirectly impact its ecological integrity,” he cautioned. “Coastal engineering projects aimed at erosion control outside the sanctuary can inadvertently exacerbate erosion within, posing a significant threat to turtle nesting habitats.”
In conclusion, the study serves as a clarion call for concerted efforts to mitigate the detrimental effects of erosion on critical marine habitats. The conservation of Olive Ridley turtles and their nesting grounds hinges upon proactive measures that address both natural and anthropogenic drivers of coastal degradation.
