The establishment of site condition monitoring of the sea caves of the St Kilda and North Rona Special Areas of Conservation with supplementary data from Loch Eriboll

Daniel Bernard Harries, Colin George Moore, Joanne S. Porter, William G. Sanderson, Fiona J. Ware, Lisa Kamphausen

Research output: Book/ReportCommissioned report

Abstract

Background
The purpose of the current study was to initiate site condition monitoring of the sea caves within the St Kilda and North Rona SACs. This was done to establish a baseline biological data set that would facilitate the assessment of the condition of the habitats in the future and to allow a judgement to be formed on the current condition of these habitats. Due to the extreme wave exposure of the target sites, it was necessary to consider a series of contingency survey targets in the event of weather conditions preventing access to the primary targets. Weather conditions severely limited time available for surveying the primary targets so attention was diverted to the contingency targets of Loch nam Madadh and Loch Laxford (reported separately). Additionally, cave sites in Loch Eriboll were surveyed while sheltering from strong winds and three rocky reef sites were surveyed at St Kilda when wave surge prevented access to the caves.
Main findings
St Kilda
 A total of 85 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory.
 Four caves were subject to SCM. One was fully intertidal, one was fully subtidal and the remaining two included both intertidal and subtidal components although monitoring effort was focussed on the subtidal in both cases.
 Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by bryozoan (crisid) turf, sponges and aggregations of anemones. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves.
 The biota recorded by the cave SCM was broadly consistent with prior data recorded from St Kilda caves and broadly similar to that recorded from comparable cave sites elsewhere in Scotland.
 Two intertidal and three subtidal reef sites were subject to SCM.
 Intertidal reef sites showed communities indicative of high exposure levels with vertically expanded supralittoral zones and exposure tolerant species present in the eulittoral.
 Subtidal reef biota on upward facing surfaces was characterised by kelp forests. The occasional presence of opportunistic kelp species indicated periodic disturbance events (i.e. storm damage). Vertical faces were characterised by bryozoan (crisid) turfs and aggregations of anemones.
 The biota recorded by the reef SCM was broadly consistent with prior data recorded from St Kilda reefs.
 A new species of soft coral (Clavularia) was discovered (and will be described separately).
 No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed.
 Based on available data it should be concluded that the cave and reef features were in good condition.
North Rona
 A total of 27 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory.
 Three caves were subject to SCM. Each included both intertidal and subtidal components although monitoring effort was focussed on the subtidal.
 Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges, aggregations of anemones and colonial ascidians. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves.
 The biota recorded by the SCM was broadly similar to that recorded from comparable cave sites elsewhere in Scotland.
 No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed.
 Based on available data it should be concluded that the cave feature was in good condition
Loch Eriboll
 A total of 27 potential cave sites have been identified within Loch Eriboll based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory.
 Two caves were surveyed using SCM methodology. These included both intertidal and subtidal components although monitoring effort was focussed on the subtidal.
 Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges and aggregations of the solitary ascidian Dendrodoa. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves.
 The biota recorded was broadly similar to that recorded from comparable cave sites elsewhere in Scotland.
 No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed.
Original languageEnglish
PublisherScottish Natural Heritage
Number of pages355
Volume1044
ISBN (Electronic)9781783915323
Publication statusPublished - 2018

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cave
monitoring
biota
reef
sea
historical record
scour
sponge
human activity
bryozoan
coast

Cite this

@book{fd7d3ddcc0194094b63d2d487d8c75e1,
title = "The establishment of site condition monitoring of the sea caves of the St Kilda and North Rona Special Areas of Conservation with supplementary data from Loch Eriboll",
abstract = "BackgroundThe purpose of the current study was to initiate site condition monitoring of the sea caves within the St Kilda and North Rona SACs. This was done to establish a baseline biological data set that would facilitate the assessment of the condition of the habitats in the future and to allow a judgement to be formed on the current condition of these habitats. Due to the extreme wave exposure of the target sites, it was necessary to consider a series of contingency survey targets in the event of weather conditions preventing access to the primary targets. Weather conditions severely limited time available for surveying the primary targets so attention was diverted to the contingency targets of Loch nam Madadh and Loch Laxford (reported separately). Additionally, cave sites in Loch Eriboll were surveyed while sheltering from strong winds and three rocky reef sites were surveyed at St Kilda when wave surge prevented access to the caves.Main findingsSt Kilda A total of 85 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Four caves were subject to SCM. One was fully intertidal, one was fully subtidal and the remaining two included both intertidal and subtidal components although monitoring effort was focussed on the subtidal in both cases. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by bryozoan (crisid) turf, sponges and aggregations of anemones. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded by the cave SCM was broadly consistent with prior data recorded from St Kilda caves and broadly similar to that recorded from comparable cave sites elsewhere in Scotland. Two intertidal and three subtidal reef sites were subject to SCM. Intertidal reef sites showed communities indicative of high exposure levels with vertically expanded supralittoral zones and exposure tolerant species present in the eulittoral. Subtidal reef biota on upward facing surfaces was characterised by kelp forests. The occasional presence of opportunistic kelp species indicated periodic disturbance events (i.e. storm damage). Vertical faces were characterised by bryozoan (crisid) turfs and aggregations of anemones. The biota recorded by the reef SCM was broadly consistent with prior data recorded from St Kilda reefs. A new species of soft coral (Clavularia) was discovered (and will be described separately). No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed. Based on available data it should be concluded that the cave and reef features were in good condition.North Rona A total of 27 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Three caves were subject to SCM. Each included both intertidal and subtidal components although monitoring effort was focussed on the subtidal. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges, aggregations of anemones and colonial ascidians. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded by the SCM was broadly similar to that recorded from comparable cave sites elsewhere in Scotland. No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed. Based on available data it should be concluded that the cave feature was in good conditionLoch Eriboll A total of 27 potential cave sites have been identified within Loch Eriboll based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Two caves were surveyed using SCM methodology. These included both intertidal and subtidal components although monitoring effort was focussed on the subtidal. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges and aggregations of the solitary ascidian Dendrodoa. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded was broadly similar to that recorded from comparable cave sites elsewhere in Scotland. No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed.",
author = "Harries, {Daniel Bernard} and Moore, {Colin George} and Porter, {Joanne S.} and Sanderson, {William G.} and Ware, {Fiona J.} and Lisa Kamphausen",
year = "2018",
language = "English",
volume = "1044",
publisher = "Scottish Natural Heritage",

}

TY - BOOK

T1 - The establishment of site condition monitoring of the sea caves of the St Kilda and North Rona Special Areas of Conservation with supplementary data from Loch Eriboll

AU - Harries, Daniel Bernard

AU - Moore, Colin George

AU - Porter, Joanne S.

AU - Sanderson, William G.

AU - Ware, Fiona J.

AU - Kamphausen, Lisa

PY - 2018

Y1 - 2018

N2 - BackgroundThe purpose of the current study was to initiate site condition monitoring of the sea caves within the St Kilda and North Rona SACs. This was done to establish a baseline biological data set that would facilitate the assessment of the condition of the habitats in the future and to allow a judgement to be formed on the current condition of these habitats. Due to the extreme wave exposure of the target sites, it was necessary to consider a series of contingency survey targets in the event of weather conditions preventing access to the primary targets. Weather conditions severely limited time available for surveying the primary targets so attention was diverted to the contingency targets of Loch nam Madadh and Loch Laxford (reported separately). Additionally, cave sites in Loch Eriboll were surveyed while sheltering from strong winds and three rocky reef sites were surveyed at St Kilda when wave surge prevented access to the caves.Main findingsSt Kilda A total of 85 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Four caves were subject to SCM. One was fully intertidal, one was fully subtidal and the remaining two included both intertidal and subtidal components although monitoring effort was focussed on the subtidal in both cases. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by bryozoan (crisid) turf, sponges and aggregations of anemones. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded by the cave SCM was broadly consistent with prior data recorded from St Kilda caves and broadly similar to that recorded from comparable cave sites elsewhere in Scotland. Two intertidal and three subtidal reef sites were subject to SCM. Intertidal reef sites showed communities indicative of high exposure levels with vertically expanded supralittoral zones and exposure tolerant species present in the eulittoral. Subtidal reef biota on upward facing surfaces was characterised by kelp forests. The occasional presence of opportunistic kelp species indicated periodic disturbance events (i.e. storm damage). Vertical faces were characterised by bryozoan (crisid) turfs and aggregations of anemones. The biota recorded by the reef SCM was broadly consistent with prior data recorded from St Kilda reefs. A new species of soft coral (Clavularia) was discovered (and will be described separately). No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed. Based on available data it should be concluded that the cave and reef features were in good condition.North Rona A total of 27 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Three caves were subject to SCM. Each included both intertidal and subtidal components although monitoring effort was focussed on the subtidal. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges, aggregations of anemones and colonial ascidians. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded by the SCM was broadly similar to that recorded from comparable cave sites elsewhere in Scotland. No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed. Based on available data it should be concluded that the cave feature was in good conditionLoch Eriboll A total of 27 potential cave sites have been identified within Loch Eriboll based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Two caves were surveyed using SCM methodology. These included both intertidal and subtidal components although monitoring effort was focussed on the subtidal. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges and aggregations of the solitary ascidian Dendrodoa. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded was broadly similar to that recorded from comparable cave sites elsewhere in Scotland. No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed.

AB - BackgroundThe purpose of the current study was to initiate site condition monitoring of the sea caves within the St Kilda and North Rona SACs. This was done to establish a baseline biological data set that would facilitate the assessment of the condition of the habitats in the future and to allow a judgement to be formed on the current condition of these habitats. Due to the extreme wave exposure of the target sites, it was necessary to consider a series of contingency survey targets in the event of weather conditions preventing access to the primary targets. Weather conditions severely limited time available for surveying the primary targets so attention was diverted to the contingency targets of Loch nam Madadh and Loch Laxford (reported separately). Additionally, cave sites in Loch Eriboll were surveyed while sheltering from strong winds and three rocky reef sites were surveyed at St Kilda when wave surge prevented access to the caves.Main findingsSt Kilda A total of 85 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Four caves were subject to SCM. One was fully intertidal, one was fully subtidal and the remaining two included both intertidal and subtidal components although monitoring effort was focussed on the subtidal in both cases. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by bryozoan (crisid) turf, sponges and aggregations of anemones. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded by the cave SCM was broadly consistent with prior data recorded from St Kilda caves and broadly similar to that recorded from comparable cave sites elsewhere in Scotland. Two intertidal and three subtidal reef sites were subject to SCM. Intertidal reef sites showed communities indicative of high exposure levels with vertically expanded supralittoral zones and exposure tolerant species present in the eulittoral. Subtidal reef biota on upward facing surfaces was characterised by kelp forests. The occasional presence of opportunistic kelp species indicated periodic disturbance events (i.e. storm damage). Vertical faces were characterised by bryozoan (crisid) turfs and aggregations of anemones. The biota recorded by the reef SCM was broadly consistent with prior data recorded from St Kilda reefs. A new species of soft coral (Clavularia) was discovered (and will be described separately). No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed. Based on available data it should be concluded that the cave and reef features were in good condition.North Rona A total of 27 potential cave sites have been identified within the SAC based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Three caves were subject to SCM. Each included both intertidal and subtidal components although monitoring effort was focussed on the subtidal. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges, aggregations of anemones and colonial ascidians. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded by the SCM was broadly similar to that recorded from comparable cave sites elsewhere in Scotland. No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed. Based on available data it should be concluded that the cave feature was in good conditionLoch Eriboll A total of 27 potential cave sites have been identified within Loch Eriboll based on a combination of historical records and direct observation. All available information on caves has been collated into a cave inventory. Two caves were surveyed using SCM methodology. These included both intertidal and subtidal components although monitoring effort was focussed on the subtidal. Cave biota tended to be heavily modified by the effects of scour on and near the floor of the caves. Less intensely scoured areas were characterised by a community of spirorbin worms and turfs of small sabellid tubes. A more profuse biota was present on the upper subtidal walls and this tended to be characterised by sponges and aggregations of the solitary ascidian Dendrodoa. Littoral and supralittoral zones appeared impoverished (relative to the open coast) within the caves. The biota recorded was broadly similar to that recorded from comparable cave sites elsewhere in Scotland. No evidence of anthropogenic impacts or of anthropogenic activities with potential to impact the cave or reef features was observed.

M3 - Commissioned report

VL - 1044

BT - The establishment of site condition monitoring of the sea caves of the St Kilda and North Rona Special Areas of Conservation with supplementary data from Loch Eriboll

PB - Scottish Natural Heritage

ER -