No abstract

Biofouling of ship hulls is considered as one of the oldest vectors for the transfer of aquatic invasive species. However, the introduction of non-native species by ballast water has received much more research attention. In this study, an alternative approach to dealing with biofouling was proposed for the port of Arzew, based on ship characteristics and transit routes. The strategy consisted of calculation of the surface area of biofouling of all ships calling at the port of Arzew during the period (2013–2016), to which was added spatial modeling using a Geographic Information System to highlight the most relevant information. We identified the areas that represented a high risk of species introduction according to their respective ecoregions of origin; those areas that constituted a minor risk, the type of ship that most likely promotes the establishment of non-native species by comparing the environmental similarity of the ecoregions assigned to the different ships with the environmental characteristics of the port of Arzew obtained by satellite imagery. The study showed that over a period of four years, 5,733 ships called at the port of Arzew, accumulating a total surface area of 35 million square meters. These results can be used for invasive species management purposes; such as: the application of specific regulations on ships of a certain tonnage that most promote the transfer of non-indigenous species, as well as their ecoregions of origin that present a great environmental similarity with the western Mediterranean, in order to minimize the transfer of aquatic invasive species.

No abstract

A trade policy could generate both economic and environmental impacts. This work is focused on the impacts of a bilateral trade policy on ballast water-mediated nonindigenous species (NIS) spread risk. Taking the hypothetical Sino-US trade restriction as an example, we integrate a computable general equilibrium model and a higher-order NIS spread risk assessment model to examine the impacts of bilateral trade policy on both the economy and NIS spread risks. We have two important findings. First, the Sino-US trade restriction would cause decreases in NIS spread risks to China and the US, as well as to three quarters of worldwide countries/regions. However, the rest one fourth would experience increased NIS spread risks. Second, the relationship between changes in exports and changes in NIS spread risks might not be directly proportional. This is observed with 46% of countries and regions that would see their exports increase but their NIS spread risks drop, with positive impacts on both their economies and environment under the Sino-US trade restriction. These results reveal both broader global impacts as well as the decoupled economic and ecological impacts of a bilateral trade policy. These broader impacts demonstrate the necessity for national governments, which are parties to bilateral agreements to give due consideration to the economic and environmental impacts on countries and regions outside of the agreement.