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<p>The resident population of dugongs (<i>Dugong dugon</i>) in the Gulf of Kachchh (GoK) inhabits one of the most tidally dynamic habitats (3.4&#xa0;m at Okha port and 6.2&#xa0;m at Navlakhi) across their global distribution range. Semi-diurnal tidal frequency restricts marine herbivory and necessitates adaptive foraging strategies. Within this hydrodynamic framework, we investigated determinants of foraging area selectivity using fresh feeding trails (<i>n</i> = 1507) as a dugong presence tool and mapped foraging areas at intertidal reef-flats (reef-top meadows, <i>n</i> = 6), mid-intertidal mudflats (tidal creek meadows, <i>n</i> = 4), and subtidal meadows (<i>n</i> = 3) from 2018 to 2023. To understand macro-tidal habitat use patterns, we investigated tidally vigilant foraging strategies across habitat types by modelling the response of feeding trail counts, lengths, and distance travelled from tidal refugia (coves and tidal creeks), to water depth, seagrass abundance, and sediment texture using Generalized Additive Models (Negative Binomial and Gamma GAMs). We then estimated periodic tidal accessibility restrictions at each habitat by overlaying perimeters of dugong foraging areas on constructed regional bathymetric maps (30&#xa0;m resolution) for average high tides (spring: 3.4&#xa0;m and neap: 2.8&#xa0;m) and daily low tide height (0.4&#xa0;m). Traditional habitat selectivity variables such as seagrass quality, composition, and shoot abundance variations were relatively weak predictors of the overall habitat selectivity. An estimated 73.4% of the total foraging areas mapped are tidally influenced. At all habitats, dugongs remained tidally vigilant by preferentially foraging at habitat edges adjacent to deep-water refugia rather than utilizing the full seagrass expanse. At habitat level, tidally vigilant foraging dugongs regulated distance travelled from tidal refugia based on habitats depth and seagrass abundance. Feeding trail lengths varied according to the ease with which seagrass could be excavated across habitats. At reef-top meadows, which had a higher % crude protein advantage, dugongs travelled farther from the tidal refugia to forage. Dugongs utilized tidal creeks as movement corridors for inter- and intra-habitat travel during foraging. This replicable and cost-effective model, combined with robust spatio-temporal maps of dugong habitat use and corridor networks, provides critical insights to enhance conservation strategies and improve outcomes for the endangered dugong population in the Gulf of Kachchh and similar habitats.</p>

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Investigation of tidally vigilant spatiotemporal foraging strategies of a Dugong (Dugong dugon) population in the macro-tidal Gulf of Kachchh, India

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月29日

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  • Sameeha Pathan,
  • Gem Christian,
  • K. Sivakumar,
  • J. A. Johnson

摘要

The resident population of dugongs (Dugong dugon) in the Gulf of Kachchh (GoK) inhabits one of the most tidally dynamic habitats (3.4 m at Okha port and 6.2 m at Navlakhi) across their global distribution range. Semi-diurnal tidal frequency restricts marine herbivory and necessitates adaptive foraging strategies. Within this hydrodynamic framework, we investigated determinants of foraging area selectivity using fresh feeding trails (n = 1507) as a dugong presence tool and mapped foraging areas at intertidal reef-flats (reef-top meadows, n = 6), mid-intertidal mudflats (tidal creek meadows, n = 4), and subtidal meadows (n = 3) from 2018 to 2023. To understand macro-tidal habitat use patterns, we investigated tidally vigilant foraging strategies across habitat types by modelling the response of feeding trail counts, lengths, and distance travelled from tidal refugia (coves and tidal creeks), to water depth, seagrass abundance, and sediment texture using Generalized Additive Models (Negative Binomial and Gamma GAMs). We then estimated periodic tidal accessibility restrictions at each habitat by overlaying perimeters of dugong foraging areas on constructed regional bathymetric maps (30 m resolution) for average high tides (spring: 3.4 m and neap: 2.8 m) and daily low tide height (0.4 m). Traditional habitat selectivity variables such as seagrass quality, composition, and shoot abundance variations were relatively weak predictors of the overall habitat selectivity. An estimated 73.4% of the total foraging areas mapped are tidally influenced. At all habitats, dugongs remained tidally vigilant by preferentially foraging at habitat edges adjacent to deep-water refugia rather than utilizing the full seagrass expanse. At habitat level, tidally vigilant foraging dugongs regulated distance travelled from tidal refugia based on habitats depth and seagrass abundance. Feeding trail lengths varied according to the ease with which seagrass could be excavated across habitats. At reef-top meadows, which had a higher % crude protein advantage, dugongs travelled farther from the tidal refugia to forage. Dugongs utilized tidal creeks as movement corridors for inter- and intra-habitat travel during foraging. This replicable and cost-effective model, combined with robust spatio-temporal maps of dugong habitat use and corridor networks, provides critical insights to enhance conservation strategies and improve outcomes for the endangered dugong population in the Gulf of Kachchh and similar habitats.