Journal of Marine Science and Engineering Review Boating- and Shipping-Related Environmental Impacts and Example Management Measures: A Review Troy A. Byrnes 1 and Ryan J. K. Dunn 2,* 1 5/66 Surf Parade, Broadbeach, QLD 4218, Australia; [email protected] 2 Ocean Science & Technology, RPS, P.O. Box 5692, Gold Coast MC, QLD 9726, Australia * Correspondence: [email protected] Received: 21 October 2020; Accepted: 10 November 2020; Published: 12 November 2020 Abstract: Boating and shipping operations, their associated activities and supporting infrastructure present a potential for environmental impacts. Such impacts include physical changes to bottom substrate and habitats from sources such as anchoring and mooring and vessel groundings, alterations to the physico-chemical properties of the water column and aquatic biota through the application of antifouling paints, operational and accidental discharges (ballast and bilge water, hydrocarbons, garbage and sewage), fauna collisions, and various other disturbances. Various measures exist to sustainably manage these impacts. In addition to a review of associated boating- and shipping-related environmental impacts, this paper provides an outline of the government- and industry-related measures relevant to achieving positive outcomes in an Australian context. Historically, direct regulations have been used to cover various environmental impacts associated with commercial, industrial, and recreational boating and shipping operations (e.g., MARPOL). The effectiveness of this approach is the degree to which compliance can be effectively monitored and enforced. To be effective, environmental managers require a comprehensive understanding of the full range of instruments available, and the respective roles they play in helping achieve positive environmental outcomes, including the pros and cons of the various regulatory alternatives. Keywords: anti-fouling treatments; benthic disturbance; coastal environments; environmental management; hydrocarbon pollution; MARPOL; species translocation; sewage discharge; water quality; wildlife impacts 1. Introduction Aquatic biomes covering approximately 75% of the earth’s surface contain critically important natural resources sustaining life and countless life cycles, while providing varying environmental, economic, social, and cultural services [1,2]. Such services are well documented and include the provision and storage of water supplies used for drinking and crop irrigation, power generation, oxygen production, nutrient supply and cycling, hosting important global food and pharmaceutical stocks, and climate regulation [3–5]. Furthermore, the use of water bodies for transporting commodities internationally using shipping fleets is significantly important for global commerce and trade. The provision of such services offered by aquatic biomes are often negatively impacted by continuing anthropogenic pressures [6,7]. Since the earliest times boats have served as transportation and played an important role in commerce and exploration [8]. To this day, boats continue to be an ever-present sighting throughout the world’s waterways used for transportation, leisure, and sporting pursuits. Additionally, ships (distinguished by larger size, shape, and purpose compared with boats) historically, and currently, J. Mar. Sci. Eng. 2020, 8, 908; doi:10.3390/jmse8110908 www.mdpi.com/journal/jmse J. Mar. Sci. Eng. 2020, 8, 908 2 of 49 play significant roles in ocean exploration, war-time conflicts, trade, fishing operations, migration, border security, infrastructure development and installations, as well as science/research-based efforts. The historical importance on boats and ships in today’s society is reflected in the fact that many large and capital international cities owe their existence to the ease for vessel access as preferred sites of settlement. In fact, 22 of the 32 largest cities in the world are located on estuaries [9] with sheltered navigable waters and large associated infrastructure, including ever-expanding recreational marinas, commercial harbors, and trade ports highlighting the continuing importance to this day. Boats vary in size and construction methods according to their intended purpose, available materials, or local traditions. Examples, include fishing boats which vary widely in style partly to match local conditions, pleasure craft used for recreational boating such as sailboats, ski boats, and pontoon boats, houseboats used for long-term residence or vacationing purposes, lighters and tugs used to transport cargo to and from other vessels and maneuvering assistance, respectively. Such boats are propelled either by manpower (e.g., oars or paddles), wind (e.g., sails), or engines (including fossil fuel and electric) and typically operate on inland waterways such as rivers and lakes, or in coastal waters. Ships, alternatively are larger ocean-going vessels capable of completing intercontinental travels and are designed for specific offshore purposes such as being capable of transferring high tonnages of commodities (e.g., tankers, dry and liquid cargo ships and floating production storage and offloading vessels) or large volumes of people (e.g., liners and cruisers), provide military services, or commercial fishing pursuits. Ship propulsion examples include steam turbines powered by fossil fuels or nuclear reaction, diesel engines, gas turbines, and stirling or steam engines. Through the variety of services offered by boats and ships their worth to humanity and economic prosperity is apparent. Whether it is the provision of foods from small to large-scale fishing pursuits, transportation means for commercial and recreational purposes, leisure and sporting pursuits in more developed nations, and the global distribution of commodities. However, daily operations under normal boating and shipping practices, associated onshore activities (e.g., maintenance slips or ship demolition), or accidental discharges/occurrences (e.g., explosions, groundings, or loss of contents such as oil or merchant containers) all contribute to potential environmental impacts (e.g., [10–14]). Such related impacts affect aquatic biome services, most notably through decreased water quality, introduction of alien species, physical disturbance and/or destruction of habitat, flora and fauna, influencing system structure and function, in addition to atmospheric pollutant inputs [10,11,15–17]. Furthermore, impacts are either direct or indirect occurring over varying spatial and temporal scales, according to factors such as the size and density (e.g., cumulative impacts of clustered vessels), movement and specific activity-based operations of boats and ships, and environmental settings and conditions. For example, boating impacts on inland waters may be substantial since these water bodies are smaller and have more limited water exchange compared to coastal areas. Additionally, operational requirements and associated activities may give rise to particular impacts, which at times can be challenging to detect, measure, and predict. A firm understanding of these impacts in aquatic biomes is significantly important, both on immediate and long-term time scales. Global population growth, increased trade, and forecasted increased use of recreational and tourism-based boating pursuits [11,18] will ensure that these boating- and shipping-related environmental impacts continue to increase without intervention and adoption of new technology (e.g., new antifouling agents, more energy efficient and environmentally friendly engines, environmentally friendly moorings (EFMs), etc.,). Accordingly, efforts are made to reduce these impacts in order to protect and preserve the environmental, economic, and cultural services aquatic biomes provide. The prevalence of boating- and shipping-related environmental impacts is detrimental to receiving environments and must be recognized and effectively managed to minimize the adverse effects, wherever possible, through the use of direct and indirect management tools, strategies and techniques (e.g., legislation, education, industry self-regulation, selective use of alternative technology, restrictions and management guidelines) to ensure the long-term sustainability of these environments. J. Mar. Sci. Eng. 2020, 8, 908 3 of 49 However, the management and protection from boating- and shipping-related impacts are typically varied and challenging tasks given the complexities and interconnected processes at play within aquatic systems, in addition to impacts operating over varying spatial and temporal scales, varying user groups with competing needs and believed responsibilities, ambitions, economic interests, and potential exploitation of legal disparities, and inefficient coordination within and between different (nations) maritime zones [16,19,20]. Furthermore, given the transient and widespread nature of maritime zones, controlling their environmental impacts from numerous diffuse and mobile sources is much more difficult than managing discharges from smaller numbers of fixed-point sources, which often proves a resource and financially demanding assignment. Where there are large numbers of intermittent pollution sources, the cost of ensuring compliance through publicly funded patrols and enforcement is high, governments may only obtain political support for such an approach where the expected social and environmental benefits are equally significant [16]. Differences in boating-related environmental management measures have been shown to be associated principally with patterns