The Marine Life Information Network

Evidence suggests that current deep-sea temperatures are generally low and stable (A. Levin & Le Bris, 2015; Pachauri et al., 2014). However, global mean sea surface temperatures have shown decadal increases of 0.11°C (1971-2010), and it has been reported by the Intergovernmental Panel on Climate Change (IPCC) that the effects of ocean warming are likely to impact depths ranging to 3000 m at the seafloor (A. Levin & Le Bris, 2015; Pachauri et al., 2014). Deep waters off the continental shelf (200 – 2,500 m) are predicted to see a lower temperature rise (ca 1°C) than shallow water habitats by the end of this century, regardless of the climate change scenario modeled (FAO (Fisheries and Aquaculture Organisation), 2019).

Cerianthids can occur across wide temperature (8.36 – 11.51°C) and depth (238 – 1,070 m) ranges in UK deep-sea environments and Hydrozoans have been recorded in depths ranging to 8400 m, indicating adaptations to varied thermal niches throughout the water column (Davies et al., 2014; Stepanjants & Chernyshev, 2015). However, deep-sea environments are generally very stable and slow to change, therefore, a warming of 1°C may have deleterious impacts on sessile deep-sea organisms, resulting in changes in depth and latitudinal species distributions (Levin & Le Bris, 2015). Furthermore, studies have indicated that increased temperature can have pervasive stimulatory impacts on benthic invertebrate metabolism until lethal levels are reached (Byrne, 2011a). However, large knowledge gaps limit current understanding of the ecological feedbacks which may occur to Cerianthids as a result of climate change driven temperature increase.

Elevated seawater temperature has been found to influence Hydrozoan metabolites; trigonelline abundance has been reduced in polyps exposed to warmer conditions, resulting in impaired polyp production (Boco et al., 2019). Therefore, restricted metabolic function resulting from increased temperature may reduce Hydrozoan abundances under projected ocean warming scenarios.  In addition, Sabellid reproductive cycles have been documented to be directly influenced by temperature, with spawning periods and larval dispersal regulated by seasonal temperature variation (Nash & Keegan, 2003). Changes in reproduction periods have been documented for some Sabellids in relation to climate change, highlighting that warming conditions have altered settlement periods, and therefore, subsequent life cycle stages (Giangrande et al., 2010). However, due to the lack of data, the full impacts of seawater temperature increase as a result of climate change on Sabellids are poorly understood, and it is likely that changes to structure forming benthos will disrupt ecological equilibriums developed over long periods of time (Giangrande et al., 2010). Organisms that require temperature cues to synchronise external fertilization may therefore, experience inhibited reproduction as a result of temperature changes.

Sensitivity Assessment. Under all scenarios (middle and high emission, and extreme scenarios), waters off the continental shelf are expected to increase marginally by approximately 1°C. Cerianthids have been recorded across broad temperature (8.36 – 11.51°C) and depth (238 – 1,070 m) ranges within UK deep-sea environments, suggesting that species within Cerianthidae can adapt to a diversity of thermal niches (Davies et al., 2014). However, sessile organisms, adapted to stable deep-sea environments may be at risk of pervasive stimulatory impacts arising from temperature increases of 1°C, resulting in changes in depth and latitudinal species distributions (Levin & Le Bris, 2015; Gibson et al., 2011). Furthermore, increased seawater temperature has been documented to inhibit metabolic function within some Hydrozoans, resulting in impaired polyp production, although evidence was not found documenting these impacts to species relevant to the UK deep-sea. Research has also indicated that temperature fluctuations resulting from climate change have altered reproduction and settlement periods for Sabellids, therefore synchronicity required for external fertilisation and reproduction may be impaired as a result of temperature change (Giangrande et al., 2010; Nash & Keegan, 2003). Data paucity was highlighted as a key limiting factor in understanding the ecological feedbacks which may arise from global warming (Byrne, 2011b). However, it is possible that temperature increases could impact all organisms considered characteristic of this biotope. Resistance for the biotope is assessed as ‘Medium’, but with 'Low' confidence. Global warming is considered a long-term, ongoing pressure, from which recovery is not possible, therefore, resilience is assessed as ‘Very low’ and overall sensitivity is assessed as ‘Medium’.

Evidence suggests that current deep-sea temperatures are generally low and stable (A. Levin & Le Bris, 2015; Pachauri et al., 2014). However, global mean sea surface temperatures have shown decadal increases of 0.11°C (1971-2010), and it has been reported by the Intergovernmental Panel on Climate Change (IPCC) that the effects of ocean warming are likely to impact depths ranging to 3000 m at the seafloor (A. Levin & Le Bris, 2015; Pachauri et al., 2014). Deep waters off the continental shelf (200 – 2,500 m) are predicted to see a lower temperature rise (ca 1°C) than shallow water habitats by the end of this century, regardless of the climate change scenario modeled (FAO (Fisheries and Aquaculture Organisation), 2019).

Cerianthids can occur across wide temperature (8.36 – 11.51°C) and depth (238 – 1,070 m) ranges in UK deep-sea environments and Hydrozoans have been recorded in depths ranging to 8400 m, indicating adaptations to varied thermal niches throughout the water column (Davies et al., 2014; Stepanjants & Chernyshev, 2015). However, deep-sea environments are generally very stable and slow to change, therefore, a warming of 1°C may have deleterious impacts on sessile deep-sea organisms, resulting in changes in depth and latitudinal species distributions (Levin & Le Bris, 2015). Furthermore, studies have indicated that increased temperature can have pervasive stimulatory impacts on benthic invertebrate metabolism until lethal levels are reached (Byrne, 2011a). However, large knowledge gaps limit current understanding of the ecological feedbacks which may occur to Cerianthids as a result of climate change driven temperature increase.

Elevated seawater temperature has been found to influence Hydrozoan metabolites; trigonelline abundance has been reduced in polyps exposed to warmer conditions, resulting in impaired polyp production (Boco et al., 2019). Therefore, restricted metabolic function resulting from increased temperature may reduce Hydrozoan abundances under projected ocean warming scenarios.  In addition, Sabellid reproductive cycles have been documented to be directly influenced by temperature, with spawning periods and larval dispersal regulated by seasonal temperature variation (Nash & Keegan, 2003). Changes in reproduction periods have been documented for some Sabellids in relation to climate change, highlighting that warming conditions have altered settlement periods, and therefore, subsequent life cycle stages (Giangrande et al., 2010). However, due to the lack of data, the full impacts of seawater temperature increase as a result of climate change on Sabellids are poorly understood, and it is likely that changes to structure forming benthos will disrupt ecological equilibriums developed over long periods of time (Giangrande et al., 2010). Organisms that require temperature cues to synchronise external fertilization may therefore, experience inhibited reproduction as a result of temperature changes.

Sensitivity Assessment. Under all scenarios (middle and high emission, and extreme scenarios), waters off the continental shelf are expected to increase marginally by approximately 1°C. Cerianthids have been recorded across broad temperature (8.36 – 11.51°C) and depth (238 – 1,070 m) ranges within UK deep-sea environments, suggesting that species within Cerianthidae can adapt to a diversity of thermal niches (Davies et al., 2014). However, sessile organisms, adapted to stable deep-sea environments may be at risk of pervasive stimulatory impacts arising from temperature increases of 1°C, resulting in changes in depth and latitudinal species distributions (Levin & Le Bris, 2015; Gibson et al., 2011). Furthermore, increased seawater temperature has been documented to inhibit metabolic function within some Hydrozoans, resulting in impaired polyp production, although evidence was not found documenting these impacts to species relevant to the UK deep-sea. Research has also indicated that temperature fluctuations resulting from climate change have altered reproduction and settlement periods for Sabellids, therefore synchronicity required for external fertilisation and reproduction may be impaired as a result of temperature change (Giangrande et al., 2010; Nash & Keegan, 2003). Data paucity was highlighted as a key limiting factor in understanding the ecological feedbacks which may arise from global warming (Byrne, 2011b). However, it is possible that temperature increases could impact all organisms considered characteristic of this biotope. Resistance for the biotope is assessed as ‘Medium’, but with 'Low' confidence. Global warming is considered a long-term, ongoing pressure, from which recovery is not possible, therefore, resilience is assessed as ‘Very low’ and overall sensitivity is assessed as ‘Medium’.

Evidence suggests that current deep-sea temperatures are generally low and stable (A. Levin & Le Bris, 2015; Pachauri et al., 2014). However, global mean sea surface temperatures have shown decadal increases of 0.11°C (1971-2010), and it has been reported by the Intergovernmental Panel on Climate Change (IPCC) that the effects of ocean warming are likely to impact depths ranging to 3000 m at the seafloor (A. Levin & Le Bris, 2015; Pachauri et al., 2014). Deep waters off the continental shelf (200 – 2,500 m) are predicted to see a lower temperature rise (ca 1°C) than shallow water habitats by the end of this century, regardless of the climate change scenario modeled (FAO (Fisheries and Aquaculture Organisation), 2019).

Cerianthids can occur across wide temperature (8.36 – 11.51°C) and depth (238 – 1,070 m) ranges in UK deep-sea environments and Hydrozoans have been recorded in depths ranging to 8400 m, indicating adaptations to varied thermal niches throughout the water column (Davies et al., 2014; Stepanjants & Chernyshev, 2015). However, deep-sea environments are generally very stable and slow to change, therefore, a warming of 1°C may have deleterious impacts on sessile deep-sea organisms, resulting in changes in depth and latitudinal species distributions (Levin & Le Bris, 2015). Furthermore, studies have indicated that increased temperature can have pervasive stimulatory impacts on benthic invertebrate metabolism until lethal levels are reached (Byrne, 2011a). However, large knowledge gaps limit current understanding of the ecological feedbacks which may occur to Cerianthids as a result of climate change driven temperature increase.

Elevated seawater temperature has been found to influence Hydrozoan metabolites; trigonelline abundance has been reduced in polyps exposed to warmer conditions, resulting in impaired polyp production (Boco et al., 2019). Therefore, restricted metabolic function resulting from increased temperature may reduce Hydrozoan abundances under projected ocean warming scenarios.  In addition, Sabellid reproductive cycles have been documented to be directly influenced by temperature, with spawning periods and larval dispersal regulated by seasonal temperature variation (Nash & Keegan, 2003). Changes in reproduction periods have been documented for some Sabellids in relation to climate change, highlighting that warming conditions have altered settlement periods, and therefore, subsequent life cycle stages (Giangrande et al., 2010). However, due to the lack of data, the full impacts of seawater temperature increase as a result of climate change on Sabellids are poorly understood, and it is likely that changes to structure forming benthos will disrupt ecological equilibriums developed over long periods of time (Giangrande et al., 2010). Organisms that require temperature cues to synchronise external fertilization may therefore, experience inhibited reproduction as a result of temperature changes.

Sensitivity Assessment. Under all scenarios (middle and high emission, and extreme scenarios), waters off the continental shelf are expected to increase marginally by approximately 1°C. Cerianthids have been recorded across broad temperature (8.36 – 11.51°C) and depth (238 – 1,070 m) ranges within UK deep-sea environments, suggesting that species within Cerianthidae can adapt to a diversity of thermal niches (Davies et al., 2014). However, sessile organisms, adapted to stable deep-sea environments may be at risk of pervasive stimulatory impacts arising from temperature increases of 1°C, resulting in changes in depth and latitudinal species distributions (Levin & Le Bris, 2015; Gibson et al., 2011). Furthermore, increased seawater temperature has been documented to inhibit metabolic function within some Hydrozoans, resulting in impaired polyp production, although evidence was not found documenting these impacts to species relevant to the UK deep-sea. Research has also indicated that temperature fluctuations resulting from climate change have altered reproduction and settlement periods for Sabellids, therefore synchronicity required for external fertilisation and reproduction may be impaired as a result of temperature change (Giangrande et al., 2010; Nash & Keegan, 2003). Data paucity was highlighted as a key limiting factor in understanding the ecological feedbacks which may arise from global warming (Byrne, 2011b). However, it is possible that temperature increases could impact all organisms considered characteristic of this biotope. Resistance for the biotope is assessed as ‘Medium’, but with 'Low' confidence. Global warming is considered a long-term, ongoing pressure, from which recovery is not possible, therefore, resilience is assessed as ‘Very low’ and overall sensitivity is assessed as ‘Medium’.

Marine heatwaves caused by increased air-sea flux of heat are only expected to penetrate surface waters (≤ 50 m) (Cerrano et al., 2000, Garrabou et al., 2009; Dan Smale, pers. comms.). Cerianthid anemones and burrowing megafauna in Atlantic mid bathyal mud are deep-sea biotopes, relevant to the Atlantic mid bathyal zone, at depths of 600 – 1300 m. Therefore, the biotope will not be affected by changes arising from marine heatwaves, and the assessment at the pressure benchmark is ‘Not relevant’.

Marine heatwaves caused by increased air-sea flux of heat are only expected to penetrate surface waters (≤ 50 m) (Cerrano et al., 2000, Garrabou et al., 2009; Dan Smale, pers. comms.). Cerianthid anemones and burrowing megafauna in Atlantic mid bathyal mud are deep-sea biotopes, relevant to the Atlantic mid bathyal zone, at depths of 600 – 1300 m. Therefore, the biotope will not be affected by changes arising from marine heatwaves, and the assessment at the pressure benchmark is ‘Not relevant’.

Sustained anthropogenic emissions of carbon dioxide (CO₂)  into the atmosphere have contributed to a net flux of CO₂ into the global ocean, resulting in pH decline through ocean acidification (Byrne, 2011b). However, despite the emerging evidence highlighting the variations in seawater pH due to climate change, understanding of the impacts of ocean acidification on deep-sea benthic ecology is limited (Danovaro, 2018).

Decreased pH, and therefore shoaling of the calcium carbonate saturation horizon, may adversely impact UK sessile benthic communities (Danovaro et al., 2017). However, cerianthid anemones and sabellids (with the exception of Glomerula, a non-UK genus) are not calcifying organisms, and therefore, may not be impacted by inhibited calcification due to pH decline. In addition, evidence has indicated that some sabellids can maintain high homeostatic capacity and adaptability when exposed to elevated pCO₂, although the species analysed in the studies were not UK, deep-sea organisms (Calosi et al., 2013; Del Pasqua et al., 2019). Furthermore, analyses focussing on taxa present in the North Atlantic have indicated that deep-sea communities containing cerianthids may not be adversely impacted by ocean acidification (Johnson et al., 2018). Knowledge gaps and data paucity were highlighted as key limitations in the study, therefore, conclusive assessments of pH decline impacts to such communities could not be made (Johnson et al., 2018).

Ocean acidification has been documented to reduce calcification rates in some hydrocorals (de Barros Marangoni et al., 2017). In addition, hydrozoan metabolites required for cell protection from osmotic and thermal stress (betaine) have been found to be inhibited under extreme acidification (pH 7.7-7.75) as a result of climate change (Boco et al., 2019). However, such analyses have not been undertaken for deep-sea organisms within UK marine environments. In contrast, studies utilising over 40 years of Continuous Plankton Recorder (CPR) data from the North Sea have indicated a significant correlative relationship between increased Hydrozoan abundance and a temporal pH decline of 0.2 (Attrill et al., 2007; Fabry et al., 2008). Furthermore, some hydrozoans have been indicated to have high tolerances to wide pH variability, exhibiting complete mortality at pH 4 and 10, and with high survival rates (>50%) within the pH range of 5 – 8.5 (Gutierre, 2012). However, this assessment was not conducted for deep-sea species and tolerance ranges are likely to be species specific, therefore, it is possible that these findings cannot be inferred beyond the study.

Sensitivity Assessment. Cerianthids and sabellids (with the exception of Glomerula, a non-UK genus) are not calcifying organisms, therefore, they are not considered to be impacted by the shoaling of the calcium carbonate saturation horizon due to ocean acidification (Danovaro et al., 2017). In addition, some sabellids have indicated the ability to adapt to acidification by maintaining high homeostatic capacity when exposed to seawater with elevated pCO₂ concentrations (Calosi et al., 2013; Del Pasqua et al., 2019). Ocean acidification may limit calcification in some hydrocorals and has also been attributed to inhibiting metabolic function in hydrozoan metabolites required for cell protection against osmotic and thermal stress. (Boco et al., 2019; de Barros Marangoni et al., 2017). However, these impacts have not been documented in UK deep-sea environments and may be species-specific. Conversely, some hydrozoans have been found to be highly tolerant to wide pH ranges and CPR data have indicated a significant correlative relationship between increased hydrozoan abundance and increased acidification in the North Sea (Attrill et al., 2007; Fabry et al., 2008; Gutierre, 2012). However, data paucity has been identified as a key factor limiting understanding of acidification impacts to deep-sea biotopes (Johnson et al., 2018). Acidification at depth is driven by the solubility (thermohaline circulation) and biological pumps, which takes orders of magnitude longer than the air-to-surface-water CO₂ exchange (Giering & Humphreys, 2017; Jones et al., 2014).

Sustained anthropogenic emissions of carbon dioxide (CO₂)  into the atmosphere have contributed to a net flux of CO₂ into the global ocean, resulting in pH decline through ocean acidification (Byrne, 2011b). However, despite the emerging evidence highlighting the variations in seawater pH due to climate change, understanding of the impacts of ocean acidification on deep-sea benthic ecology is limited (Danovaro, 2018).

Decreased pH, and therefore shoaling of the calcium carbonate saturation horizon, may adversely impact UK sessile benthic communities (Danovaro et al., 2017). However, cerianthid anemones and sabellids (with the exception of Glomerula, a non-UK genus) are not calcifying organisms, and therefore, may not be impacted by inhibited calcification due to pH decline. In addition, evidence has indicated that some sabellids can maintain high homeostatic capacity and adaptability when exposed to elevated pCO₂, although the species analysed in the studies were not UK, deep-sea organisms (Calosi et al., 2013; Del Pasqua et al., 2019). Furthermore, analyses focussing on taxa present in the North Atlantic have indicated that deep-sea communities containing cerianthids may not be adversely impacted by ocean acidification (Johnson et al., 2018). Knowledge gaps and data paucity were highlighted as key limitations in the study, therefore, conclusive assessments of pH decline impacts to such communities could not be made (Johnson et al., 2018).

Ocean acidification has been documented to reduce calcification rates in some hydrocorals (de Barros Marangoni et al., 2017). In addition, hydrozoan metabolites required for cell protection from osmotic and thermal stress (betaine) have been found to be inhibited under extreme acidification (pH 7.7-7.75) as a result of climate change (Boco et al., 2019). However, such analyses have not been undertaken for deep-sea organisms within UK marine environments. In contrast, studies utilising over 40 years of Continuous Plankton Recorder (CPR) data from the North Sea have indicated a significant correlative relationship between increased Hydrozoan abundance and a temporal pH decline of 0.2 (Attrill et al., 2007; Fabry et al., 2008). Furthermore, some hydrozoans have been indicated to have high tolerances to wide pH variability, exhibiting complete mortality at pH 4 and 10, and with high survival rates (>50%) within the pH range of 5 – 8.5 (Gutierre, 2012). However, this assessment was not conducted for deep-sea species and tolerance ranges are likely to be species specific, therefore, it is possible that these findings cannot be inferred beyond the study.

Sensitivity Assessment. Cerianthids and sabellids (with the exception of Glomerula, a non-UK genus) are not calcifying organisms, therefore, they are not considered to be impacted by the shoaling of the calcium carbonate saturation horizon due to ocean acidification (Danovaro et al., 2017). In addition, some sabellids have indicated the ability to adapt to acidification by maintaining high homeostatic capacity when exposed to seawater with elevated pCO₂ concentrations (Calosi et al., 2013; Del Pasqua et al., 2019). Ocean acidification may limit calcification in some hydrocorals and has also been attributed to inhibiting metabolic function in hydrozoan metabolites required for cell protection against osmotic and thermal stress. (Boco et al., 2019; de Barros Marangoni et al., 2017). However, these impacts have not been documented in UK deep-sea environments and may be species-specific. Conversely, some hydrozoans have been found to be highly tolerant to wide pH ranges and CPR data have indicated a significant correlative relationship between increased hydrozoan abundance and increased acidification in the North Sea (Attrill et al., 2007; Fabry et al., 2008; Gutierre, 2012). However, data paucity has been identified as a key factor limiting understanding of acidification impacts to deep-sea biotopes (Johnson et al., 2018). Acidification at depth is driven by the solubility (thermohaline circulation) and biological pumps, which takes orders of magnitude longer than the air-to-surface-water CO₂ exchange (Giering & Humphreys, 2017; Jones et al., 2014).

Cerianthid anemones and burrowing megafauna in Atlantic mid bathyal mud are deep-sea biotopes, relevant to the Atlantic mid bathyal zone, at depths of 600 – 1300 m. Therefore, the biotope will not be affected by changes arising from sea-level rise, and the assessment at the pressure benchmark is ‘Not relevant’.

Cerianthid anemones and burrowing megafauna in Atlantic mid bathyal mud are deep-sea biotopes, relevant to the Atlantic mid bathyal zone, at depths of 600 – 1300 m. Therefore, the biotope will not be affected by changes arising from sea-level rise, and the assessment at the pressure benchmark is ‘Not relevant’.

Cerianthid anemones and burrowing megafauna in Atlantic mid bathyal mud are deep-sea biotopes, relevant to the Atlantic mid bathyal zone, at depths of 600 – 1300 m. Therefore, the biotope will not be affected by changes arising from sea-level rise, and the assessment at the pressure benchmark is ‘Not relevant’.

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