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Disentangling the impacts of heat wave magnitude, duration and timing on the structure and diversity of sessile marine assemblages.

Smale DA, Yunnie AL, Vance T, Widdicombe S - PeerJ (2015)

Bottom Line: Contrary to our expectations, the warming events had no clear, consistent impacts on the abundance of species or the structure of sessile assemblages.With the exception of 1 high-magnitude long-duration HW event, warming did not alter not assemblage structure, favour non-native species, nor lead to changes in richness, abundance or biomass of sessile faunal assemblages.Our study demonstrates the importance of using realistic treatments when manipulating climate change variables, and also suggests that biogeographical context may influence community-level responses to short-term warming events, which are predicted to increase in severity in the future.

View Article: PubMed Central - HTML - PubMed

Affiliation: Marine Biological Association of the United Kingdom, The Laboratory , Citadel Hill, Plymouth , UK.

ABSTRACT
Extreme climatic events, including heat waves (HWs) and severe storms, influence the structure of marine and terrestrial ecosystems. Despite growing consensus that anthropogenic climate change will increase the frequency, duration and magnitude of extreme events, current understanding of their impact on communities and ecosystems is limited. Here, we used sessile invertebrates on settlement panels as model assemblages to examine the influence of HW magnitude, duration and timing on marine biodiversity patterns. Settlement panels were deployed in a marina in southwest UK for ≥5 weeks, to allow sufficient time for colonisation and development of sessile fauna, before being subjected to simulated HWs in a mesocosm facility. Replicate panel assemblages were held at ambient sea temperature (∼17 °C), or +3 °C or +5 °C for a period of 1 or 2 weeks, before being returned to the marina for a recovery phase of 2-3 weeks. The 10-week experiment was repeated 3 times, staggered throughout summer, to examine the influence of HW timing on community impacts. Contrary to our expectations, the warming events had no clear, consistent impacts on the abundance of species or the structure of sessile assemblages. With the exception of 1 high-magnitude long-duration HW event, warming did not alter not assemblage structure, favour non-native species, nor lead to changes in richness, abundance or biomass of sessile faunal assemblages. The observed lack of effect may have been caused by a combination of (1) the use of relatively low magnitude, realistic heat wave treatments compared to previous studies (2), the greater resilience of mature adult sessile fauna compared to recruits and juveniles, and (3) the high thermal tolerance of the model organisms (i.e., temperate fouling species, principally bryozoans and ascidians). Our study demonstrates the importance of using realistic treatments when manipulating climate change variables, and also suggests that biogeographical context may influence community-level responses to short-term warming events, which are predicted to increase in severity in the future.

No MeSH data available.


Related in: MedlinePlus

Heat wave simulations and experimental design.Experimental design and temperature treatments. (A) Coloured bars show timings and durations of experimental phases within each HW Timing. For each Timing, a set of Field Controls (FC) remained in situ. (B) Time series indicating sea temperature at the study site (daily means are based on 72 records per day, taken every 20 min; monthly mean generated from daily temperatures recorded over 3 preceding years), as well as mean daily temperatures (n = 5 mesocosm tanks ± SD) for each HW Magnitude treatment during the experimental period.
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fig-1: Heat wave simulations and experimental design.Experimental design and temperature treatments. (A) Coloured bars show timings and durations of experimental phases within each HW Timing. For each Timing, a set of Field Controls (FC) remained in situ. (B) Time series indicating sea temperature at the study site (daily means are based on 72 records per day, taken every 20 min; monthly mean generated from daily temperatures recorded over 3 preceding years), as well as mean daily temperatures (n = 5 mesocosm tanks ± SD) for each HW Magnitude treatment during the experimental period.

Mentions: The experiment comprised of 3 phases; (1) a ‘colonisation’ phase in the field, (2) an ‘experimental’ phase within mesocosms of either 1 or 2 weeks in duration and (3) a final ‘recovery’ phase in the field (Fig. 1). The experiment was initiated at 3 different times throughout the summer of 2013 to investigate the effects of HW timing on ecological responses. For Phase 1, 36 settlement panels (20 × 20 cm, constructed from black double-skinned sheets of polypropylene, ‘Correx’) were attached to a fibreglass reinforced plastic (FRP) grid in 6 rows of 6 panels (Fig. S1). The FRP grid (L = 148 cm, W = 121 cm, D = 2.5 cm) was suspended horizontally at a depth of 1.5 m directly beneath a pontoon near to the seaward entrance of the marina. Panels were faced down towards the seabed in order to reduce light and sedimentation levels and therefore select for sessile fauna (rather than algae). Faunal assemblages were targeted because they are relatively well known (in terms of both taxonomy and species-specific physiology), often comprise multiple non-native species, and are relatively speciose. After a colonisation phase of ∼6 weeks, 30 panels were transported in cool boxes to the mesocosm facility at Plymouth Marine Laboratory (PML) within 1 h. Six panels were selected at random to remain on the grid throughout the experiment to serve as field-based controls. Seawater temperature at the study site was continuously monitored (every 20 min) with a ‘Hobo’ temperature logger attached to the experimental grids.


Disentangling the impacts of heat wave magnitude, duration and timing on the structure and diversity of sessile marine assemblages.

Smale DA, Yunnie AL, Vance T, Widdicombe S - PeerJ (2015)

Heat wave simulations and experimental design.Experimental design and temperature treatments. (A) Coloured bars show timings and durations of experimental phases within each HW Timing. For each Timing, a set of Field Controls (FC) remained in situ. (B) Time series indicating sea temperature at the study site (daily means are based on 72 records per day, taken every 20 min; monthly mean generated from daily temperatures recorded over 3 preceding years), as well as mean daily temperatures (n = 5 mesocosm tanks ± SD) for each HW Magnitude treatment during the experimental period.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380158&req=5

fig-1: Heat wave simulations and experimental design.Experimental design and temperature treatments. (A) Coloured bars show timings and durations of experimental phases within each HW Timing. For each Timing, a set of Field Controls (FC) remained in situ. (B) Time series indicating sea temperature at the study site (daily means are based on 72 records per day, taken every 20 min; monthly mean generated from daily temperatures recorded over 3 preceding years), as well as mean daily temperatures (n = 5 mesocosm tanks ± SD) for each HW Magnitude treatment during the experimental period.
Mentions: The experiment comprised of 3 phases; (1) a ‘colonisation’ phase in the field, (2) an ‘experimental’ phase within mesocosms of either 1 or 2 weeks in duration and (3) a final ‘recovery’ phase in the field (Fig. 1). The experiment was initiated at 3 different times throughout the summer of 2013 to investigate the effects of HW timing on ecological responses. For Phase 1, 36 settlement panels (20 × 20 cm, constructed from black double-skinned sheets of polypropylene, ‘Correx’) were attached to a fibreglass reinforced plastic (FRP) grid in 6 rows of 6 panels (Fig. S1). The FRP grid (L = 148 cm, W = 121 cm, D = 2.5 cm) was suspended horizontally at a depth of 1.5 m directly beneath a pontoon near to the seaward entrance of the marina. Panels were faced down towards the seabed in order to reduce light and sedimentation levels and therefore select for sessile fauna (rather than algae). Faunal assemblages were targeted because they are relatively well known (in terms of both taxonomy and species-specific physiology), often comprise multiple non-native species, and are relatively speciose. After a colonisation phase of ∼6 weeks, 30 panels were transported in cool boxes to the mesocosm facility at Plymouth Marine Laboratory (PML) within 1 h. Six panels were selected at random to remain on the grid throughout the experiment to serve as field-based controls. Seawater temperature at the study site was continuously monitored (every 20 min) with a ‘Hobo’ temperature logger attached to the experimental grids.

Bottom Line: Contrary to our expectations, the warming events had no clear, consistent impacts on the abundance of species or the structure of sessile assemblages.With the exception of 1 high-magnitude long-duration HW event, warming did not alter not assemblage structure, favour non-native species, nor lead to changes in richness, abundance or biomass of sessile faunal assemblages.Our study demonstrates the importance of using realistic treatments when manipulating climate change variables, and also suggests that biogeographical context may influence community-level responses to short-term warming events, which are predicted to increase in severity in the future.

View Article: PubMed Central - HTML - PubMed

Affiliation: Marine Biological Association of the United Kingdom, The Laboratory , Citadel Hill, Plymouth , UK.

ABSTRACT
Extreme climatic events, including heat waves (HWs) and severe storms, influence the structure of marine and terrestrial ecosystems. Despite growing consensus that anthropogenic climate change will increase the frequency, duration and magnitude of extreme events, current understanding of their impact on communities and ecosystems is limited. Here, we used sessile invertebrates on settlement panels as model assemblages to examine the influence of HW magnitude, duration and timing on marine biodiversity patterns. Settlement panels were deployed in a marina in southwest UK for ≥5 weeks, to allow sufficient time for colonisation and development of sessile fauna, before being subjected to simulated HWs in a mesocosm facility. Replicate panel assemblages were held at ambient sea temperature (∼17 °C), or +3 °C or +5 °C for a period of 1 or 2 weeks, before being returned to the marina for a recovery phase of 2-3 weeks. The 10-week experiment was repeated 3 times, staggered throughout summer, to examine the influence of HW timing on community impacts. Contrary to our expectations, the warming events had no clear, consistent impacts on the abundance of species or the structure of sessile assemblages. With the exception of 1 high-magnitude long-duration HW event, warming did not alter not assemblage structure, favour non-native species, nor lead to changes in richness, abundance or biomass of sessile faunal assemblages. The observed lack of effect may have been caused by a combination of (1) the use of relatively low magnitude, realistic heat wave treatments compared to previous studies (2), the greater resilience of mature adult sessile fauna compared to recruits and juveniles, and (3) the high thermal tolerance of the model organisms (i.e., temperate fouling species, principally bryozoans and ascidians). Our study demonstrates the importance of using realistic treatments when manipulating climate change variables, and also suggests that biogeographical context may influence community-level responses to short-term warming events, which are predicted to increase in severity in the future.

No MeSH data available.


Related in: MedlinePlus