Cease or prohibit shipping
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 3
Background information and definitions
Shipping (here meaning the movement of any commercial vessels, including cargo ships but also fishing ships) can impact subtidal benthic invertebrates through physical disturbance, introduction of non-native species and pollution. When shipping is undertaken for fishing, it can also lead to additional pressure from the fishing activities. Shipping can be stopped or prohibited in specific areas. For instance, buffer zones around windfarm structures or gas platforms are usually set and exclude any ship from entering (Coates et al. 2016). In these instances, shipping closures also act as fisheries closures. These exclusion zones can either be temporary, such as during the windfarm construction (Roach et al. 2018), or permanent (Bergman et al. 2015). Ceasing shipping activities can potentially benefit subtidal benthic invertebrates by reducing and/or removing this pressure, allowing them to potentially recover over time. A direct consequence of ceasing shipping is the cessation of fishing, and in particular bottom trawling, for which evidence has been summarised under “Threat: Biological Resource Use – Cease or prohibit bottom trawling”. Evidence for related interventions are summarised under “Threat: Biological resource use – Cease or prohibit all types of fishing” and “Establish temporary fisheries closure”, as well as under “Habitat restoration and creation – Place anthropogenic installations (e.g. windfarms) in an area to act as artificial reefs and reduce the level of fishing”. Evidence related to the creation of Particularly Sensitive Sea Areas which regulate and manage shipping (IMO Resolution A.982(24)) is summarised under “Habitat protection – Designate a Particularly Sensitive Sea Area (PSSA) to regulate impactful maritime activities”.
Bergman M.J.N., Ubels S.M., Duineveld G.C.A. & Meesters E.W.G. (2015) Effects of a 5-year trawling ban on the local benthic community in a wind farm in the Dutch coastal zone. ICES Journal of Marine Science, 72, 962–972.
Coates D.A., Kapasakali D.A., Vincx M. & Vanaverbeke J. (2016) Short-term effects of fishery exclusion in offshore wind farms on macrofaunal communities in the Belgian part of the North Sea. Fisheries Research, 179, 131–138.
IMO Assembly Resolution 24/982 (2005) Revised guidelines for the identification and designation of Particularly Sensitive Sea Areas.
Roach M., Cohen M., Forster R., Revill A.S., Johnson M. & Handling editor: Steven Degraer. (2018) The effects of temporary exclusion of activity due to wind farm construction on a lobster (Homarus gammarus) fishery suggests a potential management approach. ICES Journal of Marine Science, 75, 1416–1426.
Supporting evidence from individual studies
A before-after, site comparison study in 2003–2004 in areas of soft seabed sediment in the German Bight, southern North Sea, Germany (Dannheim et al. 2014) found that, during the 12–14 months after closing an area to shipping, community energy flow (related to community structure) at sites within the closed area did not change, but it increased in nearby open sites where shipping occurred. Before shipping closure, community energy flow was similar in the closed (80 kJ/m2) and open sites (66 kJ/m2). After 12–14 months, community energy flow in the closed sites was similar to before (69 kJ/m2), but lower than at open sites where energy flow had increased over time (92 kJ/m2). After 12 months, species-level energy flow was higher in closed areas compared to open areas for 10 of 70 species, and lower for 7 of 70 species. In July 2003 a pilot windfarm platform was constructed, and the surrounding area (500 m radius) closed to all shipping (including fishing vessels). Invertebrates were surveyed at 10 sites inside the windfarm area and 10–18 outside (9 km away) before construction (March–August), and 12–14 months after exclusion (July–October 2004). Invertebrates were collected using a sediment grab (0.1 m2) and a beam trawl at 28 m depth. All were identified, counted, weighed, and their biomass converted to energy values (kilo Joule) using conversion factors. Energy flow was used to compare communities.Study and other actions tested
A before-and-after, site comparison study in 2008–2012 of multiple sites in an area of sandy seabed in the southern North Sea, 40–50 km off the coast of Belgium (Coates et al. 2016) found that three years after closing an area to shipping, overall community composition was different in closed and open sites where shipping occurred, but total abundance, biomass, species richness and diversity remained similar across sites. Data and analyses of community compositions were not reported. Total invertebrate abundance did not change over time and remained similar at sites closed and open to shipping, before (2008: closed 361 vs open 436 individuals/m2) and one to two years after the closure (2011–2012: 369–1,027 vs 256–458). This was also true for total biomass (2008: 802 vs 1,656; 2011–2012: 514–5,733 vs 1,392–1,864 mg/m2), species richness (2008: 10.3 vs 10.7; 2011–2012: 10.4–12.3 vs 10.3–14.7 species/sample), and diversity (reported as diversity index). In 2009-2010 a windfarm was constructed, and an area of approximately 21 km2 closed to all shipping (including fishing vessels) was established around the windfarm (500 m radius). Invertebrates were surveyed at 6–16 sites inside the windfarm area and 15–25 outside before construction in 2008, and after in 2011 and 2012 (always in September–October). Invertebrates >1 mm were collected using a sediment grab (0.1 m2) at 15–40 m depth, identified, counted, and their dried biomass measured or estimated.Study and other actions tested
A site comparison study in 2011 of seven areas of soft seabed in the southern North Sea, Netherlands (Bergmam et al. 2015) found that overall, an area closed to shipping had similar invertebrate abundance, biomass, species richness and diversity, compared to six adjacent open areas where shipping occurred, after five years. For each metric, not all data were shown. From core samples, all areas had similar invertebrate abundance (min. 1,096/m2; (closed area); max. 1,778/m2 (open area)), biomass (min. 32 g/m2 (closed area); max. 17 g/m2 (open area)), number of species (closed: 16; open: 13–20), and diversity (as diversity indices). From dredge samples, invertebrate abundance and species diversity were similar in the closed area and five of six open areas, while all areas had similar biomass (min. 61 g/m2 (closed area); max. 134 g/m2 (closed area)) and number of species (closed: 20; open: 15–21). An offshore wind farm was constructed in 2006, with a 500 m buffer zone (approximately 25 km2) around it closed to all shipping (including fishing vessels). Invertebrates inside the closed area and at six nearby open areas were surveyed in February 2011 using two methods. Shorter-lived infauna (>1 mm) were sampled using sediment core (0.078 m2; 16 samples across the closed area; 8 samples/open areas). Longer-lived infauna and epifauna (>7 mm) were sampled using a dredge (20 m2; 14 samples across the closed area; 6 samples/open areas). All invertebrates were identified, counted, and weighed (results are for dry weights).Study and other actions tested