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<p>Human activities have transformed natural environments. For example, fisheries can alter prey availability and cause trophic changes in seabirds. Along the southeastern coast of South America inhabits the vulnerable Olrog’s Gull (<i>Larus atlanticus</i>), considered a specialist for having an estuarine crab-based diet. Since the 1970s fishing activity in Argentina has increased. Moreover, there are reports of Olrog’s Gulls interacting with fishing activities, whose discards can provide a predictable anthropogenic food source for the gulls. This trophic modification can be studied using stable isotope analysis. Here, we compare the isotopic niches of Olrog’s Gull based on historical material (1918–1960) and recent measurements (2014). We expected recent samples to show lower <i>δ</i>¹³C and higher <i>δ</i>¹⁵N values, reflecting increased consumption of fish from fisheries at the expense of estuarine crabs. Our results showed a decrease in both <i>δ</i>¹³C and <i>δ</i>¹⁵N values in recent samples, but only <i>δ</i>¹⁵N values were statistically significant. These results may reflect environmental isotopic changes driven by human activities which have caused a trophic shift in Olrog’s Gull’s diet. However, the results do not show fishing activity as the main cause of change through the recent period, but other anthropogenic disturbances as agricultural development and urban waste availability might be playing a role. These findings provide insights for conservation, as they indicate that anthropogenic alterations in coastal ecosystems are influencing feeding ecology of this threatened species.</p>

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Coastal environments in the Anthropocene: a comparison of historical and recent isotopic niches in the threatened Olrog’s Gull Larus atlanticus

  • 期刊论文

  • 发表日期：

    2026年3月5日

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  • Aylen María de Prinzio,
  • Sofía Copello,
  • Rocío Mariano-Jelicich

摘要

Human activities have transformed natural environments. For example, fisheries can alter prey availability and cause trophic changes in seabirds. Along the southeastern coast of South America inhabits the vulnerable Olrog’s Gull (Larus atlanticus), considered a specialist for having an estuarine crab-based diet. Since the 1970s fishing activity in Argentina has increased. Moreover, there are reports of Olrog’s Gulls interacting with fishing activities, whose discards can provide a predictable anthropogenic food source for the gulls. This trophic modification can be studied using stable isotope analysis. Here, we compare the isotopic niches of Olrog’s Gull based on historical material (1918–1960) and recent measurements (2014). We expected recent samples to show lower δ¹³C and higher δ¹⁵N values, reflecting increased consumption of fish from fisheries at the expense of estuarine crabs. Our results showed a decrease in both δ¹³C and δ¹⁵N values in recent samples, but only δ¹⁵N values were statistically significant. These results may reflect environmental isotopic changes driven by human activities which have caused a trophic shift in Olrog’s Gull’s diet. However, the results do not show fishing activity as the main cause of change through the recent period, but other anthropogenic disturbances as agricultural development and urban waste availability might be playing a role. These findings provide insights for conservation, as they indicate that anthropogenic alterations in coastal ecosystems are influencing feeding ecology of this threatened species.