Annex IV protected areas: water dependent habitats and species and high status sites




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3.6. Surface water dependent habitats.





Habitat Code

Habitat Name

Structure and functions (Condition)

Overall Conservation Status

3110


Oligotrophic waters containing very few minerals of sandy plains (Littorelletalia uniflorae) (52)

Bad

Bad

3130

Oligotrophic to mesotrophic standing waters with vegetation of the Littorelletea uniflorae and/or of the Isoëto-Nanojuncetea (26)

Bad

Bad

3140

Hard oligo-mesotrophic waters with benthic vegetation of Chara spp. (26)

Bad

Bad

3150

Natural eutrophic lakes with Magnopotamion or Hydrocharition-type vegetation (11)

Unknown

Bad

3160

Natural dystrophic lakes and ponds (18)

Bad

Bad

3260


Watercourses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation (26)

Bad

Bad

3270

Rivers with muddy banks with Chenopodion rubri p.p. and Bidention p.p. vegetation (1)

Favourable

Favourable

6430

Hydrophilous tall herb fringe communities of plains and of the montane to alpine levels (19)

Inadequate

Inadequate

91E0

*Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-padion, Alnion incanae, Salicion albae) (50)

Bad

Bad

Note #: The number of SACs in which each habitat occurs as either a qualifying interest, or is present, is given in brackets. * Priority Annex 1 listed habitats are indicated with * and are bold-faced.

Colour-coded to represent the 2007 Article 17 Conservation Status assessment: green = favourable, amber = unfavourable-inadequate, red = unfavourable-bad. Grey = unknown.

Surface water dependent habitats occur as a qualifying interest in 87 SACs. It should be noted that three of the habitat types included in this group also have a significant groundwater dependency as follows:


  • 3140 Hard oligo-mesotrophic waters with benthic vegetation of Chara spp.

  • 3270 Rivers with muddy banks with Chenopodion rubri p.p. and Bidention p.p. vegetation

  • 91E0 *Alluvial forests with Alnus glutinosa and Fraxinus excelsior

(Alno-padion, Alnion incanae, Salicion albae)

Rivers generally are groundwater dependent to a varying degree, particularly at low flows.



3.6.1. Lake habitats 3110, 3130, 3140, 3150, 3160.

The Article 17 Conservation Status Assessment Report for lake habitats indicates that substantial work remains to be done in elucidating Habitats Directive Annex 1 lake types in Ireland. The detailed distribution and characteristics of the different Annex 1 lake habitats are not well documented currently. Notwithstanding this difficulty, the conservation status of Annex 1 lake habitats, in the context of the national resource including lakes within and outside the Natura 2000 network of Protected Areas, has been assessed as uniformly bad. The Annex 1 listed lake habitats are naturally oligotrophic, with the exception of 3150_natural eutrophic lakes which can be regarded as mesotrophic in EPA terminology.


NPWS is currently planning lake survey work, originally scheduled to commence in 2009 but now deferred to 2010 because of budgetary and staff resource constraints. These surveys will focus on defining the resource based on biotic communities (algae, other plants, invertebrates and fish) and will link the communities described to the WFD lake typology. NPWS considers that further refinement of the Habitats Directive Annex 1 listed lake habitat types, which are based mainly on macrophyte communities, is necessary in order to produce a meaningful conservation classification system for Irish lakes. The NPWS lake survey project will also design and initiate a monitoring programme to assess the conservation status of the relevant Annex 1 lake habitats.
It should be noted that some of the Habitats Directive Annex 1 listed lake habitats are highly oligotrophic (3110, 3140, 3160). Where WFD lake status has been downgraded because of evidence of unfavourable conservation status under the Habitats Directive, and this is related to water quality pressures, it is important to ensure that high status environmental quality standards are applied as a measure to restore favourable conservation status. It is possible that for some Annex 1 listed lake habitats, high status environmental quality standards may not be stringent enough for the protection of highly oligotrophic lakes. Lake survey work by NPWS should be accompanied by investigative monitoring of water quality in order to clarify these issues and ensure that appropriate standards are applied so that favourable conservation status is restored.
For example, the Water Framework Directive requires water chemistry monitoring which may not indicate any exceedance of relevant water quality standards for a particular lake. Habitats Directive biotic and macrophyte community monitoring of the same lake may indicate adverse impacts on community structure, or on the abundance of more sensitive species (for example some of the Charophyte species in lake habitat 3140_ Hard oligo-mesotrophic waters with benthic vegetation of Chara spp), which could be explained by lake bed sediment loadings of Phosphorus. Where these kinds of discrepancies arise, it is important that the results of monitoring programmes carried out under different legislation are compared, and monitoring protocols and/or WFD ecological status assessment adjusted, to ensure that the causes of unfavourable conservation status under the Habitats Directive are fully understood, and additional remedial measures are put in place. The Lough Carra/Mask Complex SAC (Site Code 001774) is an example of a lake complex where sediment monitoring would be recommended to help elucidate observed pressures on Habitats Directive Annex 1 listed qualifying interests.
The threats and pressures identified in the Article 17 conservation status assessments for Annex 1 listed lake habitats are listed below. The reporting procedure for these assessments follows a standard format of reporting impacts and activities affecting habitats and species (see Appendix 5), and is not accompanied by water quality monitoring; EPA water quality data are referred to. Pressures relate to current activities, and threats relate to likely future activities expected to give rise to pressures. Eutrophication, acidification, direct impacts on habitats, and the presence of alien species are the main pressures and threats identified. Hydrological pressures on lakes and their associated habitats and species arising from abstraction may be under-reported in Article 17 assessments, although a number of specific instances are noted in Appendix 8.


Lake type

3110 - 3130 -3140

3150

3160

Main pressures

120 Fertilisation

140 Grazing

160 General Forestry management

310 Peat Extraction

700 Pollution

954 Invasive species



120 Fertilisation

140 Grazing

160 General Forestry management

700 Pollution

954 Invasive species


140 Grazing

150 Restructuring agricultural land holding

160 General Forestry management

180 Burning

310 Peat Extraction

311 Hand-cutting of peat

312 Mechanical removal of peat

810 Drainage



Threats

120 Fertilisation

140 Grazing

160 General Forestry management

310 Peat Extraction

403 Dispersed habitation

600 Sport and leisure structures

700 Pollution

954 Invasive species



120 Fertilisation

140 Grazing

160 General Forestry management

403 Dispersed habitation

600 Sport and leisure structures

700 Pollution

954 Invasive species


140 Grazing

150 Restructuring agricultural land holding

160 General Forestry management

180 Burning

312 Mechanical removal of peat

810 Drainage



Note that the dystrophic lake type 3160 can arise artificially because of anthropogenic impacts on 3110 and 3130 lake types, principally from afforestation on blanket bog and wet heath within the catchment, resulting in high colour and low pH (3-6) and consequent loss of 3110/3130 plant communities. The natural pH range for dystrophic lakes is 3-6.



The Draft European Communities Environmental Objectives (Surface Water) Regulations (2008) provide a framework within which the more stringent environmental requirements of the Habitats Directive can be addressed, although it should be noted that resource issues arise in meeting the timescales envisaged for the clarification of WFD ecological status versus HD conservation status issues.
A number of individual lakes within SACs, which are currently assessed by NPWS as being at unfavourable conservation status, are identified in the SAC_Water_Dependency database, and in Appendix 8 of this guidance.


3.6.1.1. Protected species occurring in lake habitats.


Najas flexilis.


Common name

Scientific name

Main pressures and threats

Slender Naiad (25)

Najas flexilis

Eutrophication, acidification

The number of SACs in which Najas flexilis occurs as either a qualifying interest, or is present, is given in brackets.
The Annex II listed plant slender naiad Najas flexilis occurs in lakes that are transitional between hard water and soft water types. It has been recorded in a total of 49 lakes, and continues to be present in 36 lakes, with three known extinctions, and 10 sites at which its status is uncertain. It occurs in 25 SACs, and is listed as a Qualifying Interest in 24 of them. Najas is a small annual plant, and population size can vary substantially between years; because of this, uncertain status can not be taken as proof of extinction currently, but indicates that further surveys should be informed by assessment of risks and pressures. Conservation status is assessed as favourable in 29 lakes, 8 of which are not covered by a nature conservation designation currently. The species occurs in Donegal, Leitrim, Mayo, Galway and Kerry. Connemara in west Galway appears to be the species Irish stronghold with 25 of the 49 recorded populations occurring there. Eutrophication from agriculture and dispersed habitation are the main pressures/threats; acidification is also a threat. The full site list and details for Najas flexilis is held by NPWS. A database summarising these details is attached to this guidance (see Appendix 10 for the definition table); lake water bodies requiring measures under the Habitats Directive for Najas are identified in this and in the SAC_Water_Dependency database (see Figure 3 below).
The conservation status assessment backing documentation drew attention to Ballynakill Lough (SEG_CD 32_479) as being among the 30 lakes at favourable conservation status for Najas flexilis, but also as having a particularly diverse aquatic flora with a number of rare species. Comments like these which arise from individual species surveys are useful in identifying water bodies likely to be close to reference condition, which may merit high status listing under the Water Framework Directive with associated protective measures, and the creation of new or the extension of existing conservation designation boundaries to cover an appropriate area including and around them.


Figure 3. Conservation status of the Habitats Directive Annex 2 listed plant species Najas flexilis, which currently occurs in 46 lakes.

Annex II listed species otters, fish and crayfish make use of lake habitats, but are considered under river habitat 3260 below. The freshwater pearl mussel Margaritifera margaritifera also occurs in some lakes


3.6.1.2. Arctic char.


Arctic char are not listed in Annexes to the Habitats Directive, but have been included as a water dependent species because of their threatened status, high lake water quality requirement and hence usefulness as an indicator species, and vulnerability to water abstraction. Their presence is an indicative element of high lake water body ecological status. They are very vulnerable to eutrophication. Spawning and nursery areas used by Arctic char are located in shallow lake margins, and these are vulnerable if low water levels coincide with the spawning and early development stages of the fish, impacting on the extent of spawning habitat available and also on invertebrate prey. Abstraction related structures including impoundments and dams can also permanently block access by Arctic char and other fish species, including the Habitats Directive Annex 2 listed (in freshwater only) salmon.
Data provided by the Irish Char Conservation Group for current char lakes have been linked to EPA water body codes by the Western RBD; this database includes information on current threats and pressures and is attached to this guidance (see Appendix 11 for the definition table).


Figure 4. Current distribution of Arctic char in Ireland.

3.6.2. River and associated habitats



3260: Watercourses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation

The overall area of this habitat is based on all rivers. High gradient channels where the typical vegetation communities of 3260 do not occur, have been included for Fontinalis (a moss species) dominated communities. River habitat 3260 is listed as a qualifying interest in 21 SACs and is listed as present in a further 5 SACs. Information on the structure and functions, and on overall conservation status, is taken from EPA monitoring results and WFD risk assessments, and indicates bad conservation status as regards the overall national resource. Conservation status assessments are not currently available for the individual SAC qualifying rivers. A survey of Annex 1 listed river habitats by NPWS is expected to start in 2009.


The Unshin River SAC in Co. Sligo is among the better known rivers in terms of existing ecological data, although this dates mainly from the 1990s. This largely un-drained system flows across several geological boundaries between sandstone, shales and limestone, resulting in unusual physico-chemical qualities. The Unshin is regarded as exceptionally diverse for both aquatic and channel margin macrophytes, and has un-modified lowland sections which are unique in Ireland and almost unknown elsewhere in Europe. It requires WFD high status and a Q value of 4-5 to 5 to maintain it at favourable conservation status
The main pressures and threats to river habitat type 3260 are assessed as arising from eutrophication from point and diffuse sources, forestry related pressures, and hydrological change. Siltation is a significant ecological pressure, although this pollutant has not been subject to the same level of investigation as other parameters of water quality and has tended to be under-reported. The sensitivities of individual rivers are related to the presence of sensitive Annex 2 listed water dependent fauna (see Section 3.6.2.1 below).

3270 - Rivers with muddy banks with Chenopodion rubri p.p. and Bidention p.p. vegetation

In Ireland, this water dependent habitat is associated principally with turloughs, where it occurs in damp, nutrient-rich soils subject to flooding and where the vegetation is dominated by annual plants. It thus occurs mainly in riverine turloughs which are naturally eutrophic, and is associated with livestock trampling and dunging which add to the waterborne nutrients. The habitat also occurs sporadically on the beds of reservoirs, for example at the Gearagh in Co. Cork. The extent of this habitat fluctuates from year to year in relation to flooding/drying out. Its conservation status is favourable. Only one SAC site is specifically listed for this habitat currently, however it does occur as a vegetation community within sites listed for other qualifying interests, notably turloughs. WFD good status measures are thought to be sufficient to protect this habitat in rivers.



91E0 *Alluvial forests with Alnus glutinosa and Fraxinus excelsior

(Alno-padion, Alnion incanae, Salicion albae)

The remaining native broadleaved woodlands are very fragmented in Ireland, and invasive non-native species are often present, leading to some difficulties in defining woodlands which conform to the 91E0 habitat classification. A broad approach has been taken in the conservation status assessment; alluvial forests are defined as occurring in areas subject to periodic flooding along rivers, and along lake shores. Three alluvial forest variations are recognised: alder/ash riparian woodland on alluvial soils, riparian alluvial willow woodland which may also include oak and ash, and alluvial willow alder woodland beside lakes, which can also include black poplar.
Alluvial forests flood from river and lake water, but most sites are also subject to ground water inputs and marginal springs are often present, they are thus vulnerable to hydrological pressures including groundwater abstractions.
Drainage ditches within and around the boundaries of alluvial woodland areas have been recorded in 46% of sites, and drain removal/blocking has been recommended by NPWS as a management measure. Arterial drainage schemes and other hydrological alterations have resulted in a reduction in the incidence and duration of flooding in some sites.

6430 Hydrophilous tall herb fringe communities of plains and of the montane to alpine levels

This habitat occurs along the margins of watercourses and is dominated by herbs, and is not well described in Ireland. It is included within the scope of a national grassland survey that has been initiated by NPWS and which will elucidate the extent of, and variation within the habitat. The main threats and pressures to this habitat are identified in the conservation status assessment as drainage and river channel maintenance works, dykes and embankments which limit the occurrence of the habitat, and invasion by alien species especially Himalayan balsam Impatiens glandulifera.




3.6.2.1. Annex II listed species of river channels.

A number of Annex II listed water dependent species of fauna occur in river channels, both within SACs as Qualifying Interests, within SACs but not noted as a Qualifying Interest, and outside the current conservation site designation network:




Common name (#)

Scientific name

Main pressures and threats

Otter (140)

Lutra lutra

Terrestrial and aquatic habitat loss, pollution, disturbance, road fatalites

River Lamprey (10)

Lampetra fluviatilis

In-stream works

Brook Lamprey (16)

Lampetra planeri

In-stream works

Sea Lamprey (11)

Petromyzon marinus

River channel obstruction; weirs, in-stream works

Atlantic Salmon (freshwater only) (61)

Salmo salar

Eutrophication, forestry related pressures, siltation

Allis Shad (5)

Alosa alosa

River channel obstruction; weirs, eutrophication, fisheries (by-catch)

Twaite Shad (8)

Alosa fallax fallax

River channel obstruction; weirs, eutrophication, fisheries (by-catch)

White-clawed Crayfish (22)

Austropotamobius pallipes

Point discharges, siltation

alien species



Freshwater Pearl-mussel (28)

Margaritifera margaritifera

Loss of Q5+ water quality, siltation

Nore freshwater pearl mussel (1)

Margaritiefera durrovensis

Loss of Q5+ water quality, siltation

Note: Annex II listed fauna species, colour-coded to represent the 2007 Article 17 Conservation Status assessment: green = favourable, amber = unfavourable-inadequate, red = unfavourable-bad. Grey = unknown.

#: The number of SACs in which each species occurs as either a qualifying interest, or is present, is given in brackets

Where present in rivers, freshwater pearl mussels are the most sensitive receptors in terms of water quality and status, and this Section provides summary information for these species. Further details for all Annex 2 listed river species can be found on www.npws.ie

Fresh water pearl mussel Margaritifera species.

Readers are referred to the Article 17 conservation status backing documentation for Margaritifera margaritifera and M. durrovensis for detailed descriptions of both species, the pressures and threats identified for them, and how they operate on these now very highly threatened species. All populations are at unfavourable-bad conservation status, mainly because of continuous failure to produce new generations of mussels because of the loss of clean gravel beds in rivers. Gravels have become infiltrated by fine sediment and/or overgrown by biofilm (including bacteria, fungi, benthic microalgae (including diatoms) and microfauna), filamentous green algae (macroalgae), or macrophytes. All of these block the required levels of oxygen from reaching juvenile mussels, which spend the first 5 – 10 years buried within the river bed substrate.


The freshwater pearl mussel M. margaritifera lives in oligotrophic, acid to neutral waters of rivers flowing over granite or sandstone rock, mainly in the western part of Ireland, but also in areas of the south and south east where geological conditions allow. The ecology of the species is particularly notable in that individuals can grow to very large sizes relative to other freshwater molluscs, building up thick calcareous valves, in rivers that have soft water with low levels of calcium. Their shell building is consequently very slow, and individuals in natural conditions live to over a hundred years of age. M. margaritifera requires stable cobble and gravel substrate with very little fine material below pea-sized gravel. Adult mussels are two-thirds buried and juveniles up to 5-10 years old are totally buried within the substrate. The lack of fine material in the river bed substrate allows for free water exchange between the open river and the water within the substrate. The free exchange of water means that oxygen levels within the substrate do not fall below those of the open water. This is essential for juvenile recruitment, as this species requires continuous high oxygen levels.
There are 93 known surviving populations of M. margaritifera in Ireland. This species is listed as a qualifying interest in 19 SACs, with several qualifying populations in some of them. It is recognised by NPWS however, that further survey work is required to check and confirm the current range, particularly for the populations that have not been listed as qualifying interests and which lie at least partly in a further 9 SACs. This work is ongoing as part of a rapid assessment survey for the species, which also includes assessment of recoverability of juvenile habitat.
The Nore freshwater pearl mussel Margaritifera durrovensis does not live in acid waters like M. margaritifera. It is currently only known only from the lime-rich waters of the River Nore. The Nore population stretches from Poorman’s Bridge (S 407 859) to Lismaine Bridge(S 442 660), with most of the population found between Poorman’s Bridge and the Avonmore Creamery above Ballyragget (S 440 722). Margaritifera durrovensis is critically endangered both globally and in Ireland (Moorkens 2006a). For a species to have a chance of survival, a single population is not enough. The aim, therefore, is to introduce a second population to at least one other river to give the species a better chance of survival. A captive breeding programme is underway (since 2005) to aid this process, but has, to date, met with little success. Surveys are also ongoing to identify suitable translocation sites within the wider Nore catchment, however none have yet been found.
Improving the conservation status of the two fresh water pearl mussel species represents a considerable challenge, as both species are critically dependent on high water status. Management planning and measures are considered in Sections 5 and 7 of this guidance.
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