Ecosystem modifiers have the ability to significantly alter the ecosystem they inhabit sometimes with
serious consequences for their own populations. We evaluated the ability of green turtles (Chelonia
mydas) to modify seagrass ecosystems by their foraging activity. This study was conducted in a seagrass-
dominated lagoon in the Lakshadweep Islands, Indian Ocean, where a stable high-density congregation
of green turtles is present. We determined a gradient of turtle density in the lagoon and measured
the intensity of turtle herbivory across the gradient. We then measured the impact of increasing grazing
on seagrass structural parameters, growth and flowering along this gradient. Our results indicate that turtles
substantially change seagrass meadow structure (canopy height, shoot length, width and density),
reduce flowering and can potentially even cause changes in the species composition of the meadow.
We discuss the implications of these results for seagrass ecosystem function, green turtle movement
and human attitudes. When conserving ecosystem modifiers like the green turtle, any management strategy
needs to include a detailed knowledge of the roles these species play in the ecosystems they inhabit.
into the future, with dramatic increases in urbanization and peri-urban
development (vanAsselen andVerburg,2013). Consequently, identifying
priority sites for conservation characterized by minimal human conflict
that would require minimal direct investment of effort and resources
for effective protection is critical (Myers et al., 2000)
Environmental niche modelling, alternatively known as species distribution modelling, (ecological) niche modelling, predictive habitat distribution modelling, and climate envelope modelling refers to the process of using computer algorithms to predict the distribution of species in geographic space on the basis of a mathematical representation of their known distribution in environmental space (= realized ecological niche). The environment is in most cases represented by climate data (such as temperature, and precipitation), but other variables such as soil type, water depth, and land cover can also be used. These models allow for interpolating between a limited number of species occurrence and they are used in several research areas in conservation biology, ecology and evolution.
The extent to which such modelled data reflect real-world species distributions will depend on a number of factors, including the nature, complexity, and accuracy of the models used and the quality of the available environmental data layers; the availability of sufficient and reliable species distribution data as model input; and the influence of various factors such as barriers to dispersal, geological history, or biotic interactions, that increase the difference between the realized niche and the fundamental niche. Environmental niche modelling may be considered a part of the discipline of biodiversity informatics.