Decision-making barriers challenge port administrators to adapt and build resilience to natural hazards. Heavy rains, storms, sea level rise (SLR), and extreme heat can damage the critical coastal infrastructure upon which coastal communities depend. There is limited understanding of what impedes port decision makers from investing resources in climate and extreme weather adaptations. Through semi-structured interviews of 30 port directors/managers, environmental specialists, and safety planners at 15 mediumand high-use ports of the U.S. North Atlantic, this paper contributes a typology of seven key adaptation barriers. We measured shared knowledge of the identified barriers using a cultural consensus model (CCM). Knowledge of the barriers that prevent or delay resilience investments can help the decision makers direct their resources to help reduce coastal vulnerability and support safe and sustainable operations of U.S. ports. Such actions also serve to help prepare the marine transportation system for future climate and extreme weather events.

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Climate changes projected for 2100 and beyond could result in a worldwide race for adaptation resources on a scale never seen before. This paper describes a model for estimating the cost and materials of elevating coastal seaport infrastructure in the United States to prevent damage from sea level rise associated with climate change. This study pilots the use of a generic port model (GenPort) as a basis from which to estimate regional materials and monetary demands, resulting in projections that would be infeasible to calculate on an individual port-by-port basis. We estimate the combined cost of adding two meters of additional fill material to elevate the working surface and then reconstructing the generic port. We use the resulting unit area cost to develop an estimate to elevate and retrofit 100 major United States commercial coastal ports. A total of $57 billion to $78 billion (2012 US dollars) and 704 million cubic meters of fill would be required to elevate the 100 ports by two meters and to reconstruct associated infrastructure. This estimation method and the results serve as a thought exercise to provoke considerations of the cumulative monetary and material demands of widespread adaptations of seaport infrastructure. The model can be adapted for use in multiple infrastructure sectors and coastal managers can use the outlined considerations as a basis for individual port adaptation strategy assessments.

In benthic communities sponges commonly outcompete other organisms in the race for suitable space. Superior competitive ability allows them to grow and overgrow other sessile organisms, some of these being octocorals. Acquiring substratum space, a resource often more limiting than food, is the obvious benefit of these competitive interactions. However, sponges that overgrow larger structures such as branching octocorals also change their position in the water column, and potentially their access to food and exposure to grazers. This study explored the potential benefit of sponge–octocoral associations by examining the effect of height off the bottom on growth of two species of ropelike demosponges under natural conditions. The growths of Amphimedon compressa and Iotrochota birotulata were monitored over 12 months at Cross Harbour, Great Abaco, The Bahamas, using small (5‐cm) sponge fragments that were established at three heights above the bottom (0–5, 30, 60 cm). Growth rates differed among the two species and among different heights. Over 12 months, the mean volumetric growth for A. compressa was 17.7 cm3 ± 1.4 compared with 8.9 cm3 ± 1.4 for I. birotulata. Both species had a higher growth rate at the 60‐cm level. These results suggest that these ropelike sponges benefit from their association and growth on octocorals, not only by using the octocoral skeletal axis as support, but also by acquiring exposure to higher water flow.

This research identified vulnerability indicators from open-data sources that represent the three components of vulnerability, as outlined by the Intergovernmental Panel on Climate Change: exposure, sensitivity, and adaptive capacity. With input from experts knowledgeable in port operations, planning, policy, and data, researchers refined a set of highlevel vulnerability indicators to answer the following key questions: (1) how sufficient is the current state of U.S. seaport sector data for developing expert-supported vulnerability indicators for a regional sample of ports and (2) how can indicators be used to measure the relative vulnerability (i.e., exposure, sensitivity, and adaptive capacity) of multiple ports? Using open-data sources, this study developed an Indicator-Based Vulnerability Assessment methodology that integrates multiple vulnerability indicators for ports in the North Atlantic region. The Analytic Hierarchy Process, a technique for organizing and analyzing complex decisions using pairwise comparisons, was used to develop a ranking that matched 3 of the top-4 most vulnerable ports that were subjectively identified by port experts. This demonstrates strong promise for this methodological approach to measure seaport vulnerability to climate and extreme weather events. Indices of seaport relative vulnerability to climate and extreme weather can advance goals for a resilient Marine Transportation System by informing efforts and plans to prioritize and allocate limited resources.