Abstract
The West Indian manatee, which lives at the interface of freshwater and marine systems, can serve as a representative model for potential vulnerability of nearshore species to in-water construction activities. In coastal Alabama, planned construction projects including the Mobile River Bridge and Bayway widening and Mobile ship channel expansion may impact individual manatees as well as habitat resources and migration pathways. Direct impacts to manatees such as vessel interactions, entanglement or ingestion of construction materials, and entrainment may result in acute physical injury or mortality. Indirect impacts from construction such as habitat obstruction or degradation and increased noise from construction activities can alter behavior and intra-species communication and reduce access to essential resources. While permitting requirements for in-water construction projects help to mitigate risks, manatees may be particularly vulnerable in areas like the northern Gulf of Mexico where manatee occurrence has increased in recent years and relatively few data are available on abundance and distribution. Some impacts of construction may be immediately difficult to quantify, but planned operations can implement and evaluate a variety of mitigation strategies pre-, during, and post-construction to prevent large-scale negative outcomes. As human populations increasingly occupy coastal zones across the globe, effective planning of coastal development and in-water construction of bridges, marinas, boat launches, and other infrastructure will be essential to support conservation efforts for manatees and other species at-risk in affected areas.
