BSEP116B Biodiversity in the Baltic Sea - Helcom

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Bearing in mind the complex hydrographic conditions, and the fact that most Baltic Sea organisms live at the edge of their physiological tolerance range, anthropogenic chemical pollution has to be seen as a further stress factor acting upon Baltic Sea biodiversity. Only during recent decades have we started to gain advanced understanding on how multiple stressors (e.g., salinity, temperature, hypoxia and chemical pollution) in combination may affect biota and, thus, biodiversity. 6.7 Alien species Chinese mitten crab (Eriocheir sinensis), Bothnian Bay, Finland other surfaces has been required since 2008 (see also Chapter 6.2, Maritime activities). The Baltic is a sea of invaders as most animal and plant species there are postglacial immigrants. In contrast to distribution by natural spreading mechanisms, alien species are defined as ”species or lower taxa occurring outside of their natural range (past or present) and dispersal potential...” (IUCN 2002). Some alien species have become invasive, i.e., an alien whose population undergoes an exponential growth stage and rapidly extends its range (Occhipinti-Ambrogi & Galil 2004). 118 EU legislation concerning hazardous substances includes the Regulation 2006/1907/EC concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), the Integrated Pollution Prevention and Control Directive (96/61/ EC) and the Water Framework Directive (60/2000/ EC) complemented with a list of priority substances (2455/2001/EC and a proposal COM(2006)397). In addition, many HELCOM recommendations concern the limitation of chemical pollution, including HELCOM Recommendation 19/5 on the HELCOM Strategy for hazardous substances. 6.6.4 Conclusions There are encouraging signs of decreasing concentrations and impacts on biota of certain hazardous substances for which there are long-term monitoring data. At the same time, there are increasing concerns about the occurrence and negative biological effects of substances such as TBT/TPhT, PFOS, dioxins, furans and dioxin-like PCBs. The effects of specific substances on Baltic biodiversity are difficult to estimate owing to a lack of ecotoxicological information or a lack of monitoring data concerning both the occurrence of substances and their biological effects in the Baltic marine environment. Alien species act as modifiers of biodiversity and biogeography. Owing to this, the characteristics and integrity of the Baltic developed since the last Ice Age are threatened, and the sea is subject to worldwide homogenization of the aquatic flora and fauna (Leppäkoski & Olenin 2001). Recent establishment of a number of alien species populations can be considered as biocontamination (Arbačiauskas et al. 2008) of the indigenous Baltic ecosystem because the invaders have caused alterations in the taxonomic structure of the invaded communities. In the Baltic, these changes have been restricted mainly to the family and genus level. For example, more than every second established alien species included in the Baltic Sea Alien Species Database (Olenin et al. 2008) belongs to genera that are not represented among the native flora and fauna of the Baltic Sea. In the inner Baltic, some newcomers contribute to taxonomic diversity at higher levels: the alien barnacle Balanus improvisus is the only representative of its order Thoracica. Similarly, the only species belonging to gambarid decapod crayfish (Orconectes limosus and O. virilis) and to mud crabs (Decapoda, Xanthidae (Rhithropanopeus harrisii)) as well as the Chinese mitten crab Eriocheir sinensis (family Grapsidae) are invaders in the Baltic. Only one native comb jelly species
(Pleurobrachia pileus) represents the phylum Ctenophora; in addition, an introduced species ( Mnemiopsis leidyi) has become established since 2006. Furthermore, only one native cumacean crustacean (Diastylis rathkei) was present prior to the introduction of Stenocuma graciloides, first found in 2004. One of the management objectives of the maritime segment of the Baltic Sea Action Plan (BSAP) is ‘No introductions of alien species from ships’. In addition, the biodiversity segment of the BSAP includes the specific target: “To prevent adverse alterations of the ecosystem by minimising, to the extent possible, new introductions of non-indigenous species”. 6.7.1 Trends and impacts Trends Since the early 1800s, about 120 alien species have been recorded in the Baltic Sea including the Kattegat (Figure 6.7.1, Box 6.7.1). The invasion rate for the region was approximately 1.3 new alien species every year over the period 1961–2007 (derived from the Baltic Sea Alien Species Database 2008). Since World War II, 81 new alien species have been recorded in the Baltic, 35 species of which have been ship-assisted. Eight new species have been observed during the past five years alone. Many of the past invaders are currently widespread and occur in high densities in the coastal areas of the Baltic Sea; for example, the barnacle Balanus improvisus and the bivalve Dreissena polymorpha, but also Number of observations 35 30 25 20 15 10 5 0 1801-1820 1821-1840 Unknown Associated Ornamental Stocking Shipping 1841-1860 1861-1880 1881-1900 1901-1920 Time period 1921-1940 1941-1960 1961-1980 1981-2000 2001-2008 Figure 6.7.1. Number of new alien species observed since the early 1800s in the Baltic Sea (including the Kattegat) and likely vector of introduction (derived from the Baltic Sea Alien Species Database, update 10 April 2008). Note that the last bar only covers the past 8 years, while the other bars cover 20-year periods. Individuals per m 2 12000 10000 8000 6000 4000 2000 Monoporeia Macoma 0 1964 1968 1971 1974 1978 1985 1989 1992 1995 1998 2001 Individuals per m 2 120 100 80 60 40 20 Marenzelleria 0 1964 1968 1971 1974 1978 1985 1989 1992 1995 1998 2001 Figure 6.7.2. Long-term changes in the Tvärminne area, western Gulf of Finland, in the abundance of zoobenthos described as density (individuals per m 2 on y-axis) of the dominant native species (Macoma balthica, the Baltic clam, and Monoporeia affinis, an amphipod crustacean) and the invasive North American bristle worm Marenzelleria spp. Note the difference in abundance scales (Laine et al. 2001). Photos by Ari O. Laine (Monoporeia (top) and Macoma (middle)) and Johanna Stigzelius (Marenzelleria (bottom)). 119
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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
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Denmark Estonia Finland Germany Lat
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Mud-sandflat, Greifswald Lagoon, Ge
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3 COMMUNITIES Communities are assem
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32 Spring bloom index 1200 1000 800
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34 Unusual events and new species i
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36 Depth limit (m) the Gulf of Both
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Number of species 16 14 12 10 8 6 4
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Figure 3.2.7. Left panel shows pred
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Implications for the Baltic Sea Act
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Biomass (wet weight, mg per m 2 ) B
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the other hand, is not selected by
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iomass can be used to assess enviro
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Average number of species 20 15 10
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52 Macoma baltica where the influen
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the total BT identified for each ma
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Recruitment (thousands) 8000000 700
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Alien species Several alien fish sp
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4 SPECIES The number of species in
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Table 4.1.1. Results of dedicated a
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Number of stranded porpoises 180 16
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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 78 and 79: sites outside the Baltic, decreased
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 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
Page 128 and 129: 6.8.2 Activities generating noise i
Page 130 and 131: 128 and fish in the Baltic Sea area
Page 132 and 133: 800 700 600 bag of the two German B
Page 134 and 135: Fish swarm on kelp (Laminaria sp.)
Page 136 and 137: tion of ice cover, either through r
Page 138 and 139: 7 STATUS OF THE NETWORK OF MARINE A
Page 140 and 141: Box 7.1. Natura 2000 network of pro
Page 142 and 143: 25 20 on how the criteria on ecolog
Page 144 and 145: estrial, nearshore marine, and offs
Page 146 and 147: 144 >30 psu 18-30 psu 11-18 psu 7.5
Page 148 and 149: Permission needed Restricted Forbid
Page 150 and 151: Figure 7.8.a. MARXAN ’best portfo
Page 152 and 153: The BSPA network is relatively well
Page 154 and 155: Mammals. Among the mammals, the pop
Page 156 and 157: 154 taxonomic groups and communitie
Page 158 and 159: 156 provided by an ecosystem. Use o
Page 160 and 161: 158 Reduction of human pressures Wh
Page 162 and 163: 160 fishing on fish population dyna
Page 164 and 165: 162 Baden, S., Boström, C. (2001).
Page 166 and 167: 164 Season 2001-2002. Acta Zoologic
Page 168 and 169: 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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BSEP116B Biodiversity in the Baltic Sea - Helcom

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