BSEP116B Biodiversity in the Baltic Sea - Helcom

nutrients, underwater noise, oil spills, and the
spreading of alien species. Many of the marine protected
areas (MPAs), which have been established
to protect the unique marine nature of the Baltic
Sea from human impact, are close to heavily trafficked
areas (Figure 6.2.1).
Maritime traffic is addressed by one of the four
main segments of the Baltic Sea Action Plan (BSAP).
A number of management objectives have been
established to indicate the main areas of concern
including, e.g., ’Safe maritime traffic without accidental
pollution’, ‘Minimum sewage pollution from
ships’, ‘No introductions of alien species from ships’,
and ‘Minimum air pollution from ships’.
6.2.1 Impacts of maritime traffic on
biodiversity
Nutrient inputs
Shipping activity contributes to the eutrophication
of the Baltic Sea through emissions of nitrogen
oxides (NOx) and discharges of nitrogen and
phosphorus contained in sewage (for impacts on
biodiversity, see Chapter 6.5, Eutrophication). NOx
emitted to air is deposited both directly onto the
sea surface and in the catchment area, from where
part of the nitrogen drains into the sea via rivers.
NOx deposited onto the Baltic Sea is particularly
effective in causing eutrophication because it is
directly available for use by primary producers.
According to the Co-operative Programme for
Monitoring and Evaluation of the Long-Range
Transmission of Air Pollutants in Europe, EMEP
(Bartnicki 2007), shipping in the Baltic Sea contributed
9% of the total airborne nitrogen deposition
directly to the sea in 2005. The major share of
nutrients to the Baltic enters as waterborne input
from the catchment area (Knuuttila 2007) and
shipping contributes only about 2% of the total
nitrogen inputs to the Baltic Sea (Table 6.2.1). A
recent study, however, suggests that, based on
NOx emissions from ships, nitrogen deposition may
be somewhat higher than previously estimated
(Stipa et al. 2007). With a projected 2.6% annual
increase in shipping traffic in the Baltic, and assuming
no abatement measures, the estimated annual
input of NOx from maritime traffic alone has been
estimated to increase by roughly 50% until 2030
(Stipa et al. 2007, IMO document MEPC 57/INF14).
Nitrogen loads to the Baltic Sea originating from
ships’ sewage discharges have been estimated to
represent about 0.05% of the total waterborne
nitrogen load and up to 0.5% of the total phosphorus
load to the Baltic Sea (Table 6.2.1) (Huhta
et al. 2007). These figures have been calculated
based on the assumption that there is no sewage
treatment onboard ships (cargo ships, cruise ships
and passenger/car ferries) and that all sewage is
discharged into the sea, i.e., the theoretical worstcase
scenario. The proportion of nutrients originating
from ships’ sewage water is thus relatively small
compared to the total nutrient load to the Baltic
Sea. Nutrients in sewage discharge may nevertheless
have considerable effects on the growth of
pelagic phytoplankton because the nutrients are
discharged directly to the open sea ecosystem. The
amount of total nitrogen discharges from commercial
ship traffic is comparable to the 500 tonnes
of annual nitrogen load from the city of Helsinki
sewage treatment plant, which purifies the sewage
of approximately 1 million people (Huuska & Miinalainen
2007).
Table 6.2.1. Magnitude of nitrogen (N) and phosphorus (P) inputs from shipping, including nitrogen deposition
from airborne emissions and sewage, and total waterborne and airborne loading of nitrogen and
phosphorus to the Baltic Sea. Note that the estimates concern either the year 2000 or 2005.
Nitrogen Total N in 10 3 tonnes NOx in 10 3 tonnes
Airborne N deposition from Baltic shipping in 2005 1 19 14
Total deposition of airborne N to the Baltic Sea in 2005 1 208 86
Sewage N from Baltic shipping in 2000 2 0.47 -
Waterborne loading of N to the Baltic Sea in 2005 3 620 300
Phosphorus
Total P in 10 3 tonnes
Sewage P from Baltic shipping in 2000 2 0.16 -
Waterborne loading of P to the Baltic Sea in 2005 3 29 -
1)
Bartnicki 2007; 2) Huhta et al. 2007; 3) Knuuttila 2007.
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