Proxy-based model to assess the relative contribution of ballast water and biofouling’s potential propagule pressure and prioritize vessel inspections

Abstract

Commercial shipping is the primary pathway of introduction for aquatic nonindigenous species (NIS), mainly through the mechanisms of ballast water and biofouling. In response to this threat, regulatory programs have been established across the globe to regulate and monitor commercial merchant and passenger vessels to assess compliance with local requirements to reduce the likelihood of NIS introductions. Resource limitations often determine the inspection efforts applied by these regulatory agencies to reduce NIS introductions. We present a simple and adaptable model that prioritizes vessel arrivals for inspection using proxies for potential propagule pressure (PPP), namely a ships’ wetted surface area as a proxy for the likelihood of biofouling-mediated PPP and ballast water discharge volume as a proxy for ballast water-mediated PPP. We used a California-specific dataset of vessels that arrived at California ports between 2015 and 2018 to test the proposed model and demonstrate how a finite set of inspection resources can be applied to target vessels with the greatest PPP. The proposed tool is adaptable by jurisdiction, scalable to different segments of the vessel population, adjustable based on the vector of interest, and versatile because it allows combined or separate analyses of the PPP components. The approach can be adopted in any jurisdiction across the globe, especially jurisdictions without access to, or authority to collect, risk profiling data or direct measurements for all incoming vessel arrivals.

Quantifying the probability of a successful marine bioinvasion due to source‐destination risk factors

“…Some examples are the time of year as it relates to the reproductive seasons of specific marine NIS and propagule pressure, i.e., the frequency and magnitude of marine NIS arrivals (Carlton, 1996 ; Lockwood et al., 2005 ). The latter is strongly influenced by the movement patterns of cargo vessels (Ceballos‐Osuna et al., 2021 ), i.e., the number and size of vessels transporting trade goods between various source‐destination locations (Verna et al., 2021 ), which is correlated to the strength of trade connections between regions. A complete risk assessment strategy would need to account for propagule pressure as well as the source‐destination risks (Verling et al., 2005 ).…”

Global Impacts of a Bilateral Trade Policy on Ballast Water-Mediated Species Spread Risk: A Case Study of Sino-US Trade

“…Ceballos-Osuna et al used ballast water discharge volume as a proxy to assess the relative contribution of ballast water's potential propagule pressure. 28 Bradie et al further considered environmental distance and propagule pressure with information available on ballast water reporting forms. 29 While the information on ballast water reporting forms is reliable, incomplete reporting makes a worldwide picture difficult to ascertain.…”

“…Several models or tools have been developed to estimate the ballast water-mediated NIS spread risks. Ceballos-Osuna et al used ballast water discharge volume as a proxy to assess the relative contribution of ballast water’s potential propagule pressure . Bradie et al further considered environmental distance and propagule pressure with information available on ballast water reporting forms .…”

Anglers as potential vectors of aquatic invasive species: Linking inland water bodies in the Great Lakes region of the US

“…There have been numerous and varied approaches to detection, including basic manual sampling and monitoring [8] and inspections [9]; stakeholder and participant surveys to gauge presence and magnitude of impact [4,10] or develop conceptual models [11]; and analyzing eDNA [12]. Different approaches focus on modeling and predicting spread using risk assessment and screening tools [13,14], predicting egg transport [15], modeling propagule pressure [6,[16][17][18][19], and modeling of impedance surfaces to identify leastcost pathways of likely transmission [20]. Some of these techniques include gravity models, which commonly use empirical data on current source locations and likely destinations, based on proximity and connections through transportation pathways or human activities that increase risk of spread.…”

“…In North America, freshwater invasive species include algae such as didymo; a host of other aquatic plants such, as Hydrilla and water chestnut; and animal species, ranging in size and diversity from spiny water fleas and New Zealand mud snails, to Asian carp and nutria. Transmission and spread of aquatic invasives in freshwater can occur through multiple means, including extreme storm events [ 5 ], natural dispersal and range expansion, intentional stocking, direct connections through canals and inter-basin transfer of water, transport by shipping [ 6 ], and behaviors associated with tourism and recreation (for a comprehensive review, see [ 7 ])…”