Ecosystem goals for the North Sea
In order to protect nature at sea, you must know where the valuable nature is located, what the present quality of the nature is and what kind of quality is desired. Partly on behalf of the results of the nature policy and the spatial planning of the North Sea (see the Fifth Note Environmental Planning), this kind of knowledge has been brought together in the project 'Ecosystem goals for the North Sea'. One effect of these goals has led to the nature value chart for the Dutch section of the North Sea.
In the note 'Nature for people, people for nature' from 2000, the Dutch government establilshed twelve ecosystem goals for the North Sea.
The underlying table gives an overview of the goals. The numbers refer to the explanation per goal and a table with indicators for reaching the goal.
| relationships and dynamics |
| 1 | Maintain the natural dynamic processes as an essential limiting condition for the naturalness of the sea and coastal zone (for example, the large-scale sand and mud transportations to the Wadden Sea. |
| 2 | Maintain and where necessary restore existing food chains and the related natural productivity of the sea. |
| 3 | Enlarge the estuarine character (the natural transition from fresh-brackish-saline, tidal and intertidal areas) of the coastal zone, particularly in the coastal zone. |
| biodiversity |
| 4 | Preserve and where necessary restore characteristic and biotic communities and related habitats of the sea, coastal zone and delta region. |
| 5 | At most, take incidental action against algae blooms; preserve and where necessary restore natural diversity among the plankton. |
| 6 | Maintain and where necessary restore the diversity of the bottom fauna, including populations of long-living and slowly reproductive species. |
| 7 | Promote diversity of the fish fauna by preserving and where necessary restoring:
a. spawning and nursery areas;
b. a more balanced population structure;
c. a natural range in fish stocks:
d. populations of long-living and slowly reproductive species. |
| 8 | Preserve and where necessary restore the living conditions, such as food stocks, space and breeding opportunities, for populations of molting, overwintering, migrating and breeding sea and coastal bird. |
| 9 | Preserve and where necessary restore the living conditions for populations of marine mammals. |
| value of experience |
| 10 | Maintain the possibilities for experiencing the dynamics of the forces of nature, wind, water, sand and salt at the transitions from open water to dry coastal zones. |
| 11 | Maintain the openness, splendour, quietness and obscurity; this holds true for the whole coastline in the north-south direction and perpendicular to the beach up to the line of visibilty ('clean horizon'). |
| 12 | Maintain and where necessary promote opportunities for being in the presence of various fauna, such as birds and fish. |
| Source: LNV 2000: Natuur voor mensen, mensen voor natuur. |
In the report "In sea with nature'', the assesment center LNV surveys the possible conflicts between the ecosystem goals and human activities in and around the sea. In addition, a number of goal scales are elaborated ('Parameters for Ecosystem goals in the North Sea', 2002).
Goal 1: Maintain natural dynamic processes
Sea currents and the resulting transportation of sand and mud at sea will only be disrupted by large-scale sand exploitation in deep pits. This is not taking place momentarily, however there are plans in this direction (exploiting concrete sand in the North Sea). Current patterns along the coast (the 'coastal river') can be disturbed due to the construction of the Second Maas Plain, maintenance of piers and channels, coastal defence works and, in a limited manner, from fisheries.
The suggested scales for these goals are summerized in the underlying table.
| parameter | present value | target value |
| larvae flow to coast and Wadden Sea | unobstructed | unobstructed |
| mud transportation to the Wadden Sea (106 tons/year) | 20 | 20 |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 3: Enlarge the estuarine character (particularly for delta regions)
The quality of the ecosystem in the delta waters is particularly under pressure due to continuing high concentrations of contaminated materials in the Schelde water. The concentrations of nutrients is also too high, which can lead to blossoms of toxic or plague algae. Furthermore, cockle fisheries forms a threat for the bird populations and the shellfish farming brings risks of introducing system-foreign species into the delta waters (as happened with the Pacific oyster in past decades). The construction of the Second Maasvlakte means a major intervention on the existing intertidal region.
In the large tidal waters of the Delta, the tide has been tremendously tempered by the Delta Works. Increase in the difference between high and low tide (the fall) could lead to a large increase in the areal of exposed banks.
The proposed indicators for reaching this goal are summarized in the table below:
| parameter | present value | target value |
| Exposed banks (in ha) | 20,000 | 40,000 |
| Fall (m) | decrease | increase |
| boundaries fresh/brackish/saline | disturbed | historical positions |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 5: At most, take incidental action against algae blooms; preserve and where necessary restore natural diversity among the plankton
Reaching this goal is hindered in particular by the continuing high supply of nutrients to seawater. The blossoming of non-toxic organisms, such as phaeocystis and Noctiluca scintillans can cause disorder in the ecosystem locally. Blossoming of toxic algae, such as dinophysis brings dangers for all plankton consumers, but especially for man (via shellfish). New toxic algae can end up in the North Sea ecosystem via ballast water from ships. Furthermore, one expects so much turbidity from large-scale sand exploitation that it will influence the plankton.
The proposed indicators for reaching this goal are summarized in the table below:
| parameter | present value | target value |
Nurtrients (coast) in the winter
. level N and P (-mol/l)
. proportion N and P
. emission N and P (ton/year) |
N 60-90; P 1.4-3.0
23
N 400; P24 |
N 14-24; P 0.6-0.7
16
0 |
| Chlorophyll a (mg/m3) | 15-20 | 7 |
presence plague algae (cells/liter)
. Karenia mikimotoi
. Alexandrium spp.
. Dinophysis spp.
. Pseudonitzschia spp. |
1
1
10,000
10,000,000 |
1
1
100
1000 |
| presence Pheaocystis (number days > 106 cells/liter) | 40 | 10 |
| oxygen level (mg O2/l) | 5 | 6 |
| ballast water (%treated) | 0 | 100 |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 6: Maintain and where necessary restore the diversity of the bottom fauna, including populations of long-living and slowly reproductive species
The benthic fauna in the North Sea suffers in particular from beam trawl fisheries with tickler chains. Long-living animal species, such as the quahog and the red whelk, are declining rapidly in areas where intensive flatfish fisheries take place. Other shellfish, echinoderms, crabs, lobsters and benthic fish are also disappearing to make room for a fauna consisting mostly of worms. In addition, the benthic fauna is also influenced by pollution. Eutrophication in particular can lead to disturbances or a different composition of the fauna.
The construction of the Second Maasvlakte means the disappearance of a large surface area of biotopes in a shallow coastal zone.
Oil and gas exploitation platforms have a positive effect on the benthic fauna indirectly. There is a safety zone of a radius of 500 meters around every installation, in which shipping, fisheries and activities such as sand extraction is not allowed. In these zones, the benthic fauna is not disturbed as much than elsewhere at sea. Locally, the discharge of drilling mud can lead to disturbance.
(Future) wind energy parks and possible placement of transmitting installations will also be surrounded by a safety zone which is favorable for benthic fauna.
The proposed indicators for reaching this goal are summarized in the table below:
| parameter | present value | target value |
| population size quahog in the northern NCP (number animals/m2) | 10-50 | 50 |
| population size whelk in the northern NCP (number animals/m2) | 0,01 | 0.05-1.5 |
| imposex whelk (open sea) and dog whelk (coast) (% of females) | 25-100 | <10 |
| Diversity index (Shannon-Wiener) | region-dependent 1.1-3.0 | increase |
| Areal without bottom agitation (percentage NCP less than 1x per 10 years fished) | 9 | 15 |
| Oysterbanks (ha) | 0 | 15 |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 7: Promote diversity of the fish fauna
The safety zone around offshore platforms and wind energy parks is also a refuge for benthic fish. Pollution from the offshore and shipping can form a threat. Gravel excavation is damaging for species that lay their eggs on gravel substrates (such as herring)
The fisheries has a major influence on the fish populations. The target species threaten to be overfished and unintended by-catch species, such as sharks and rays, have declined strongly in number. Sharks and rays are also sensitive to electromagnetic fields which are generated by electricity and telephone cables.
The construction of the Second Maasvlakte will probably have a significant effect on the migration of fish larvae to the nursery in the Wadden Sea, due to repositioning the coastal river.
The proposed indicators for reaching this goal are summarized in the table below:
| parameter | present value | target value |
| average size of the fish community (%>25 centimeters) | 28 | 40 |
presence of long-living species (number/km2)
. thornback ray
. greater weever |
0.1-0.3
0 |
6
50 |
spawning biomass commercial species above the precautionary level (million kilograms)
. herring
. cod
. plaice
. lesser sandeel
. sole
. whiting |
772
54
289
706
40
257 |
1300
150
300
600
35
315 |
discards (% weight of catch)
. fish
. benthic animals |
27
46 |
minimalize
minimalize |
| Diversity (numbers and species) | unknown | increase |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 8: Preserve and where necessary restore the living conditions for sea and coastal birds
Lighted drilling platforms can have negative effects on migrating birds. Birds can also be victims of gas flames during burn off of gas which is released during trial drills. Even more serious is the risks of discharges from mineral and vegetable oil from shipping.
The fisheries have positive as well as negative influence on birds. A number of sea and coastal birds become entangled in standing rigging. The shellfish fisheries in tidal and coastal regions perform an attack on the supply of staple food, such as cockles and spisula. Positive is the effect of by-catch which is thrown overboard. Gulls and petrels in particular profit.
The influence of pollution on birds is thought to be less serious. Effects of materials such as PCBs on the immune system of the birds has not been sufficiently studied.
Wind energy parks and future transmission installations bring birds the risk of collisions. Military activities disturb resting and foraging birds.
Recreation on the beach and in coastal waters can disturb foraging birds and result in the disappearance of nesting places. The construction of the Second Maasvlakte could mean the loss of a large foraging area.
The proposed indicators for reaching this goal are summarized in the table below:
| parameters | present value | target value |
| nesting pairs little terns (number) | Wadden Sea 150
Delta 350 | Wadden Sea 200
Delta 500 |
| nesting pairs Kentish plover (number) | Wadden Sea 60-80
Delta 200 | Wadden Sea 150
Delta 300 |
| common scoter (number) | 100,000 | same |
| guillemot and auk (number) | NCP 200.000
Bruine bank >1/km2 | same |
| areal nesting area little tern and Kentish plover (ha) | 2000 | 4000 |
presence staple food and small fish
. lesser sandeel
. herring
. sprat
. shellfish |
1145
825
unknown
10-225 |
1300
600
depending upon year advice
to be determined |
oil victims (% dead birds covered in oil on the beach)
. guillemot (open sea)
. common scoter (coast) |
70-80
70-80 |
0
0 |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 9: Preserve and where necessary restore the living conditions for populations of marine mammals
Because they are at the top of the food chain, marine mammals have relatively the most hinder from pollution in sea, whether it comes from offshore, shipping or from land. Reproduction and health problems can result.
Standing rigging causes problems for marine mammals. Porpoises can drown in the nets of cod fishermen, seals can drown in the fykes lacking retaining nets.
Finally, disturbance of resting seals is a problem. This can be caused by recreationists (on the beach or in tidal regions), from shipping or from military activities.
The proposed indicators for reaching this goal are summarized in the table below:
| parameter | present value | target value |
| harbour seal (number) | Wadden Sea 5000
Voordelta 130 | Wadden Sea >6500
Voordelta 300 |
| porpoise (number) | NCP 20,000
Voordelta 30 | NCP 50,000
Voordelta > 250 |
areal rest and nursing area for seals (ha)
. Wadden
. Delta |
maintain
20,000 |
40,000 |
presence staple food and small fish
. lesser sandeel
. herring
. sprat |
1145
825
unknown |
1300
600
depending upon year advice |
| by-catch marine mammals (% of the population) | 2.7 (North Sea) | <1.7 |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 10: Maintain the possibilities for experiencing the dynamics of the forces of nature, wind, water, sand and salt at the transitions from open water to dry coastal zones.
One has not been able to establish any clear effects of human activity as far as this goal is concerned.
Goal 11: Maintain the openness, splendour, quietness and obscurity; this holds true for the whole coastline in the north-south direction and perpendicular to the beach up to the line of visibilty ('clean horizon').
Static constructions such as drilling platforms and windmill parks disrupt the open horizon. On the other hand, ships at sea enlarge the feeling of an openness. Military practices and noisy forms of water recreation disturb the stillness.
The proposed scale for this goal has been summerized in the underlying table.
| parameter | present value | target value |
| unhinderd view | unknown | maintain present situation |
| Source: Parameters Ecosysteemdoelen Noordzee, Expertisecentrum LNV 2002 |
Goal 12: Maintain and where necessary promote opportunities for being in the presence of various fauna, such as birds and fish
Pollution plays a prominent role in this goal. Oil victims and marine litter substantially reduce the value of experiencing nature along the coast. In addition, disturbance due to recreation and military activities also play a role.
Source: de Vleet, Ecomare
