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Human populations are moving to coastal regions at a rapid pace, and growing populations are creating large impacts on ecological systems through the development of infrastructure and resource use. Urbanization indexes (UI) are used for a wide range of purposes related to understanding how urban growth impacts both urban development and ecological systems. Most UIs are developed using different factors, and there is a lack of standardization across studies even within the same study system. We reviewed the existing literature that utilizes a UI in the context of ecological questions within coastal regions to determine their utility in assessing how ecological impacts vary across coastal environments and are useful in identifying how urban growth is affecting ecosystems and species. We found that existing variation in UI development hampers the ability to make comparisons across studies and systems. To more fully understand the impacts of urbanization we recommend that UIs used in future studies be standardized to facilitate comparisons across time and studies. We offer guidance on how this can be done. 

ABSTRACT Climate‐induced range shifts may displace species into novel habitats where their life history characteristics may differ in response to new physiological conditions. One such species is the mangrove tree crab,Aratus pisonii, that has expanded beyond mangrove habitats into salt marshes, with the help of anthropogenic structures such as boat docks that mimic its natural habitat in many ways. Individuals in the salt marsh grow to smaller sizes and have different reproductive patterns than individuals in the native mangrove or in boat dock habitats. We examined the metabolic rates of crabs associated with each of these three habitats to determine whether changes in energy expenditure could account for the life history changes that have been documented. We found that the metabolic patterns were similar in the three habitats, with metabolic rate increasing with body size and with temperature, being higher for females than for males and increasing during reproduction. However, once these factors were accounted for, there was no additional difference in metabolic patterns between habitats. Combining these patterns with known patterns of temperature differences and differences in food intake between the mangrove, salt marsh, and boat docks provides mechanistic insight into the energy mismatch that has been created by this range expansion from mangroves to salt marshes. The energy dynamics in these different habitats are consistent with and are capable of explaining the observed patterns of life history variation that accompany this range expansion. Our study provides an example of a mechanistic approach to understanding the influence of climate change and associated range shifts on life history variation across habitat types.