BSEP116B Biodiversity in the Baltic Sea - Helcom

4 SPECIES
The number of species in the Baltic Sea, excluding
bacteria, amounts to several thousand, with the
majority belonging to the planktonic community.
The diversity of the smallest organisms, i.e., bacteria
and viruses, is largely unknown. This evaluation
of Baltic Sea diversity is primarily focused on indicators
that are often represented by selected species.
The Baltic Sea Action Plan includes the ecological
objective ‘Viable populations of species’. In this
assessment, species have mainly been addressed as
representatives of the Baltic Sea communities (see
Chapter 3). This chapter includes a special set of
species that are either threatened (Box 4.1) or associated
with specific targets in the BSAP. Particular
attention is given to the populations of the harbour
porpoise, seals, and a selection of birds. The
specific targets of the action plan related to the
respective species or species group are discussed
and recommendations provided accordingly.
4.1 Harbour porpoise
The harbour porpoise (Phocoena phocoena) occurs
in the temperate and sub-arctic zone of the northern
hemisphere. It is the only cetacean species
inhabiting, i.e., reproducing in, the Baltic Sea. As a
top predator, the harbour porpoise is an indicator
species for past and present environmental conditions
in the Baltic Sea. The population living in the
Baltic Sea is genetically distinct from the North Sea
population (reviewed in Palmé et al. 2004). Furthermore,
genetic, morphological and contaminant
studies indicate that distinct populations can be differentiated
within the Baltic Sea (e.g., Berggren et al.
1999, Huggenberger et al. 2002, Tiedemann 2001):
one population inhabits the Kattegat and Belt Sea,
whereas the other population inhabits the Baltic
Proper. According to Tiedemann (2001), the distribution
of the Kattegat/Belt Sea population might
extend into the Arkona Basin, while the northern
Box 4.1. Threatened and/or declining species in the Baltic Sea
The Baltic Sea is a unique marine ecosystem—home to both
marine and freshwater species adapted to the brackish-water
conditions. After decades of continuing human pressure,
many of the species have been pushed to their tolerance
limits, resulting in population declines, severe population
crashes and even a case of extinction. The Baltic Sea Action
Plan (BSAP) sets the goal to achieve “Thriving and balanced
communities of plants and animals” as well as “Viable populations
of species”. With this as a background, HELCOM’s
work regarding endangered or threatened species is of high
priority to fulfil the biodiversity segment of the BSAP. To
reach the goal, HELCOM has taken initial steps to identify the
threatened species and the species that are threatened or
show a declining population trend owing to direct or indirect
human pressures.
The HELCOM lists of threatened and/or declining species and
biotopes/habitats in the Baltic Sea area were adopted in 2008
(HELCOM 2007b). The species list concentrates on species that
have a clear relation to the Baltic marine environment; therefore,
it does not include freshwater species. Even with these
limitations, the list grew alarmingly long: 14 plant species,
seven species of invertebrates, 13 bird species, 23 fish species
and four mammal species. Owing to varying environmental
conditions in the different parts of the Baltic Sea area, the
HELCOM list of threatened and/or declining species specifies
the distribution and threat status for all 18 sub-regions
(HELCOM 2007b). The aim of the list is to report on species
that are in urgent need of protective measures.
According to the BSAP, a more comprehensive red list
of Baltic Sea species must be produced by 2013. A comprehensive
red list of threatened and declining species of
lampreys and fish of the Baltic Sea already exists. It includes
altogether 184 fish species from 15 monitoring areas. Based
on abundance data and known pressures on the species,
the fish assessment considered 34 species (18.5%) to be of
high priority for conservation (HELCOM 2007c). However,
many of the high priority species are still inadequately protected
or monitored, even within marine protected areas.
This first Baltic Sea-wide red list for a species group will
be updated by 2013. Before that, by 2011, the conservation
status of non-commercial fish species will be assessed.
Because coastal fish, in particular, have a structuring role
in coastal food webs, the BSAP recommends that countries
protect, monitor and sustainably manage these species and
that they develop by 2012 region-specific reference values
in order to assess the status of the populations in future.
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