BSEP116B Biodiversity in the Baltic Sea - Helcom

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sites outside the Baltic, decreased reproductive success, and threats affecting bird survival. Conservation concerns for Steller’s eider in the Baltic Sea include accidental bird mortality in fishing nets, the threat of oil pollution, and the possibility of habitat degradation. The species is extremely site-faithful and regularly occurs on very few sites. Therefore, Steller’s eiders are highly sensitive to factors affecting their wintering habitats. Long-tailed duck (Clangula hyemalis) The Baltic Sea is a globally important wintering area for the long-tailed duck. Surveys in 1992 and 1993 showed that approximately 4.3 million birds from the Fenno-Scandinavian and Russian breeding populations were wintering on offshore banks or in coastal areas of the Baltic Sea. About 66% of the wintering birds were found at four geographically limited offshore areas: Hoburgs Bank south of Gotland, Irbe Strait, the Gulf of Riga, and Pomeranian Bay (Durinck et al. 1994). However, spring migration counts in Finland and Estonia as well as regional winter surveys indicate that the total wintering population of long-tailed ducks has decreased dramatically in numbers in recent years (Kauppinen 2008, J. Bellebaum pers. comm.). Updated trends from offshore areas covered during the coordinated mid-winter census 2007–2008 will be published by the SOWBAS project in 2009 (http://sowbas. dhigroup.com/). Because the majority of the birds winter on a few offshore sites, the population may be severely affected by oil spills from ships, fishery by-catch, and habitat changes. An important shipping route from the southern Baltic Sea to the Gulf of Finland with approximately 22 000 ship passages per year passes through the Natura 2000 site Hoburgs Bank. A large number of smaller oils spills, most of them less than one tonne, are registered along the route each year. Weekly winter surveys of oiled birds at southern Gotland between 1996/1997 and 2006/2007 have shown that several tens of thousands of long-tailed ducks are killed annually by oil in the central Baltic Sea (Larsson & Tydén 2005, Larsson 2007). Furthermore, analyses of 998 long-tailed ducks drowned in fishing gear at Hoburgs Bank showed 76 Long-tailed duck (Clangula hyemalis)
80 1,20 % successful breeding pairs 70 60 50 40 30 20 10 1,00 0,80 0,60 0,40 0,20 Reproduction success 0 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 0,00 % successful breeding pairs Reproduction success Figure 4.3.7. The development of reproductive parameters of the white-tailed eagle in Mecklenburg- Western Pomerania, 1973–2008. that a large proportion, about 12% of the birds, had oil in the plumage (Larsson & Tydén 2005). Although any kind of oil discharge from ships is strictly prohibited in the Baltic Sea, chronic oiling is most likely an important reason for the decline of the European wintering population of the long-tailed duck. White-tailed eagle (Haliaeetus albicilla) The white-tailed eagle breeds in coastal and inland lake areas of all Baltic countries. These countries, together with Norway, host the major part of the European population, which currently probably accounts for more than 50% of the global population. Although the white-tailed eagle is not a ‘true’ coastal species, it reaches remarkably high concentrations in some coastal areas. The Odra lagoon area, for example, has been known as one of the last density centres during the first half of the 20th century (Mizera 2002), and currently still shows the highest density of breeding pairs in Central Europe (Hauff et al. 2007). In Lithuania, a concentration of breeding sites in the Nemunas delta and around the Curonian Lagoon is obvious (Dementavičius 2007). In Sweden also, the major part of the population is found along the coast (Tjernberg & Svensson 2007). In Finland, the species is concentrated in the southwestern coastal areas, but also occurs along the whole coastline and around large inland lakes in Lapland (SYKE 2008b). At the beginning of the 20th century, as a consequence of severe persecution, the white-tailed eagle was close to extinction all around the Baltic Sea. In Denmark, the species disappeared after 1911, in 1913 in Mecklenburg-Western Pomerania, only 23 bp were known, and the Polish population of that time was estimated at about 20 bp (Hauff & Wölfel 2002, Mizera 1999). In Lithuania and the Kaliningrad region of Russia, the white-tailed eagle also disappeared for a long time. Owing to protection measures against persecution, the population started to recover during the 1920s, but the positive trend was reversed from the mid- 1950s to the early 1980s by the harmful effects of chemical pollutants (DDT and PCBs) on fertility and reproductive success. The proportion of successful breeding pairs dropped down to only 20–30%, and the reproductive success to 0.2–0.4 fledglings per breeding pair. As a consequence, the population remained stagnant or even decreased. Owing to the ban on DDT and other pesticides in the early 1970s, the reproduction parameters started to improve at the beginning of the 1980s, and returned to normal levels in the mid-1990s (Figure 4.3.7). Currently, the white-tailed eagle population is increasing in all Baltic countries (Table 4.3.1, Figure 4.3.8). The species has also returned to territories abandoned in the past (e.g., Lithuania in 1987, Denmark in 1995). In recent years, a range expansion to the west (western and southwestern parts of Germany) has been observed, and in 2006 the first breeding pair was recorded in the Netherlands. 77
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Baltic Sea Environment Proceedings
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Published by: Helsinki Commission K
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TABLE OF CONTENTS PREFACE . . . . .
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6.6 Hazardous substances . . . . .
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1 INTRODUCTION 8 1.1 An integrated
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Box 1.1. Biodiversity The term biod
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of saline water from the North Sea
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14 On a global scale, marine ecosys
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Box 1.2. Regime shifts in the Balti
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2 MARINE LANDSCAPES AND HABITATS 18
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From an ecological point of view, a
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Box 2.1.2. The Baltic marine landsc
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• A coherent data set on benthic
Page 28 and 29: Denmark Estonia Finland Germany Lat
Page 30 and 31: Mud-sandflat, Greifswald Lagoon, Ge
Page 32 and 33: 3 COMMUNITIES Communities are assem
Page 34 and 35: 32 Spring bloom index 1200 1000 800
Page 36 and 37: 34 Unusual events and new species i
Page 38 and 39: 36 Depth limit (m) the Gulf of Both
Page 40 and 41: Number of species 16 14 12 10 8 6 4
Page 42 and 43: Figure 3.2.7. Left panel shows pred
Page 44 and 45: Implications for the Baltic Sea Act
Page 46 and 47: Biomass (wet weight, mg per m 2 ) B
Page 48 and 49: the other hand, is not selected by
Page 50 and 51: iomass can be used to assess enviro
Page 52 and 53: Average number of species 20 15 10
Page 54 and 55: 52 Macoma baltica where the influen
Page 56 and 57: the total BT identified for each ma
Page 58 and 59: Recruitment (thousands) 8000000 700
Page 60 and 61: Alien species Several alien fish sp
Page 62 and 63: 4 SPECIES The number of species in
Page 64 and 65: Table 4.1.1. Results of dedicated a
Page 66 and 67: Number of stranded porpoises 180 16
Page 68 and 69: is recommended to survey harbour po
Page 70 and 71: Number of individuals 12000 10000 8
Page 72 and 73: Mean blubber thickness (mm) 40 35 3
Page 74 and 75: Breeding pairs 60000 50000 40000 30
Page 76 and 77: predation on nests and nesting adul
Page 80 and 81: Table 4.3.1. Development of the pop
Page 82 and 83: 80 Number of breeding pairs 3000 25
Page 84 and 85: The strategic goal of the BSAP to h
Page 86 and 87: for a given site or area. The secon
Page 88 and 89: Mussel bed reef community, Jasmund,
Page 90 and 91: Table 5.3. Assessment results of th
Page 92 and 93: Aerial photo of harbours seals (Pho
Page 94 and 95: 6 HUMAN PRESSURES ON BIODIVERSITY A
Page 96 and 97: Table 6.1.1. Catch range during the
Page 98 and 99: Baltic herring trawling, Bothnian B
Page 100 and 101: 6.1.3 Major international framework
Page 102 and 103: 100 Oil turnover (millions of tonne
Page 104 and 105: NOx emissions and sewage Macrophyte
Page 106 and 107: Communication links There are a num
Page 108 and 109: Figure 6.3.3. Left: concrete-stone
Page 110 and 111: ecommendations would contribute to
Page 112 and 113: Tourist fishing 110 cial fishery fo
Page 114 and 115: 112 Figure 6.5.1. Integrated classi
Page 116 and 117: can be considered as having been a
Page 118 and 119: Although no direct, dramatic mass m
Page 120 and 121: Bearing in mind the complex hydrogr
Page 122 and 123: Box 6.7.1. Invasion status of the B
Page 124 and 125: Table 6.7.1. Examples of ecological
Page 126 and 127: munities that formerly consisted of
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6.8.2 Activities generating noise i
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128 and fish in the Baltic Sea area
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800 700 600 bag of the two German B
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Fish swarm on kelp (Laminaria sp.)
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tion of ice cover, either through r
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7 STATUS OF THE NETWORK OF MARINE A
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Box 7.1. Natura 2000 network of pro
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25 20 on how the criteria on ecolog
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estrial, nearshore marine, and offs
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144 >30 psu 18-30 psu 11-18 psu 7.5
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Permission needed Restricted Forbid
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Figure 7.8.a. MARXAN ’best portfo
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The BSPA network is relatively well
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Mammals. Among the mammals, the pop
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154 taxonomic groups and communitie
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156 provided by an ecosystem. Use o
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158 Reduction of human pressures Wh
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160 fishing on fish population dyna
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162 Baden, S., Boström, C. (2001).
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164 Season 2001-2002. Acta Zoologic
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166 Gasiūnaitė, Z.R., Cardoso, A.
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168 HELCOM & OSPAR (2003): Joint HE
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170 ICES (2008c). Report of the Bal
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172 area: density-dependent effects
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174 Noer, H., Clausager, I., Asferg
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176 Scheffer M., Carpenter S.R., Fo
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178 by passive acoustic monitoring.
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180 Warzaw, Poland Vilhunen, Jarmo,
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182 6.7 Alien speices Authors: Lepp
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ANNEX III: CONSERVATION STATUS OF T
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ANNEX IV: HABITAT OR SPECIES DISTRI
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ANNEX V: STATUS OF BREEDING AND WIN
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