Climate‐induced changes in the suitable habitat of cold‐water corals and commercially important deep‐sea fishes in the North Atlantic

Climate‐induced changes in the suitable habitat of cold‐water corals and commercially important deep‐sea fishes in the North Atlantic

Morato T, González‐Irusta, JM, Dominguez‐Carrió C, Wei C-L, Davies AJ and others

https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14996

The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodiversity and distributions of deep‐sea fauna, thereby compromising key ecosystem services. Understanding how climate change can lead to shifts in deep‐sea species distributions is critically important in developing management measures. We used environmental niche modelling along with the best available species occurrence data and environmental parameters to model habitat suitability for key cold‐water coral and commercially important deep‐sea fish species under present‐day (1951–2000) environmental conditions and to project changes under severe, high emissions future (2081–2100) climate projections (RCP8.5 scenario) for the North Atlantic Ocean. Our models projected a decrease of 28%–100% in suitable habitat for cold‐water corals and a shift in suitable habitat for deep‐sea fishes of 2.0°–9.9° towards higher latitudes. The largest reductions in suitable habitat were projected for the scleractinian coral Lophelia pertusa and the octocoral Paragorgia arborea, with declines of at least 79% and 99% respectively. We projected the expansion of suitable habitat by 2100 only for the fishes Helicolenus dactylopterus and Sebastes mentella (20%–30%), mostly through northern latitudinal range expansion. Our results projected limited climate refugia locations in the North Atlantic by 2100 for scleractinian corals (30%–42% of present‐day suitable habitat), even smaller refugia locations for the octocorals Acanella arbuscula and Acanthogorgia armata (6%–14%), and almost no refugia for P. arborea. Our results emphasize the need to understand how anticipated climate change will affect the distribution of deep‐sea species including commercially important fishes and foundation species, and highlight the importance of identifying and preserving climate refugia for a range of area‐based planning and management tools.


Molecular mechanisms underpinning transgenerational plasticity in the green sea urchin Psammechinus miliaris

Molecular mechanisms underpinning transgenerational plasticity in the green sea urchin Psammechinus miliaris

Melody s. Clark, Coleen C. suckling, Alessandro Cavallo, Clara L. Mackenzie, Michael A.S. Thorne, Andrew J. Davies & Lloyd S. Peck

www.nature.com/articles/s41598-018-37255-6

The pre-conditioning of adult marine invertebrates to altered conditions, such as low pH, can significantly impact offspring outcomes, a process which is often referred to as transgenerational plasticity (TGP). This study describes for the first time, the gene expression profiles associated with tGp in the green sea urchin Psammechinus miliaris and evaluates the transcriptional contribution to larval resilience. RNA-Seq was used to determine how the expression profiles of larvae spawned into low pH from pre-acclimated adults differed to those of larvae produced from adults cultured under ambient pH. The main findings demonstrated that adult conditioning to low pH critically pre-loads the embryonic transcriptional pool with antioxidants to prepare the larvae for the “new” conditions. In addition, the classic cellular stress response, measured via the production of heat shock proteins (the heat shock response (HsR)), was separately evaluated. None of the early stage larvae either spawned in low pH (produced from both ambient and pre-acclimated adults) or subjected to a separate heat shock experiment were able to activate the full HSR as measured in adults, but the capacity to mount an HSR increased as development proceeded. this compromised ability clearly contributes to the vulnerability of early stage larvae to acute environmental challenge.

Scale-dependent spatial patterns in benthic communities around a tropical island seascape

https://commons.wikimedia.org/wiki/File:Coral_at_Jarvis_Island_National_Wildlife_Refuge.jpg

Scale-dependent spatial patterns in benthic communities around a tropical island seascape

E. Aston, G. Williams, M. Green, A.J. Davies, L. Wedding, J. Gove, J-B. Jouffray, T. Jones, J. Clark

Understanding and predicting patterns of spatial organization across ecological communities is central to the field of landscape ecology, and a similar line of inquiry has begun to evolve sub-tidally among seascape ecologists. Much of our current understanding of the processes driving marine community patterns, particularly in the tropics, has come from small-scale, spatially-discrete data that are often not representative of the broader seascape. Here we expand the spatial extent of seascape ecology studies and combine spatially-expansive in situ digital imagery, oceanographic measurements, spatial statistics, and predictive modeling to test whether predictable patterns emerge between coral reef benthic competitors across scales in response to intra-island gradients in physical drivers. We do this around the entire circumference of a remote, uninhabited island in the central Pacific that lacks the confounding effects of direct human impacts. We show, for the first time, that competing benthic groups demonstrate predictable scaling patterns of organization, with positive autocorrelation in the cover of each group at scales.

Full Citation

E. Aston, G. Williams, M. Green, A.J. Davies, L. Wedding, J. Gove, J-B. Jouffray, T. Jones, J. Clark (Accepted) Scale-dependent spatial patterns in benthic communities around a tropical island seascape, Ecography, 10.1111/ecog.04097

Accepted MS

Download the Authors Accepted Manuscript here.

Oceanographic setting and short-timescale environmental variability at an Arctic seamount sponge ground

Oceanographic setting and short-timescale environmental variability at an Arctic seamount sponge ground

E.M. Roberts, F. Mienis, H.T. Rapp, U. Hanz, H.K. Meyer, A.J. Davies (Roberts is a Post-doc, and Meyer an MSc student with Davies)

Mass occurrences of large sponges, or ‘sponge grounds’, are found globally in a range of oceanographic settings. Interest in these grounds is growing because of their ecological importance as hotspots of biodiversity, their role in biogeochemical cycling and bentho-pelagic coupling, the biotechnological potential of their constituent sponges, and their perceived vulnerability to physical disturbance and environmental change. Little is known about the environmental conditions required for sponges to persist and for grounds to form, and very few studies have explicitly characterised and interpreted the importance of oceanographic conditions. Here, results are presented of the first observational oceanographic campaign at a known sponge ground on the Schultz Massif Seamount (SMS; Arctic Mid-Ocean Ridge, Greenland / Norwegian Seas). The campaign consisted of water column profiling and short-term deployment of a benthic lander. It was supported by multibeam echosounder bathymetry and remotely operated vehicle video surveys. The seamount summit hosted several environmental factors potentially beneficial to sponges. It occurred within relatively nutrient-rich waters and was regularly flushed from above with slightly warmer, oxygen-enriched Norwegian Arctic Intermediate Water. It was exposed to elevated suspended particulate matter levels and oscillating currents (with diurnal tidal frequency) likely to enhance food supply and prevent smothering of the sponges by sedimentation. Elevated chlorophyll a concentration was observed in lenses above the summit, which may indicate particle retention by seamount-scale circulation patterns. High sponge density and diversity observed on the summit is likely explained by the combination of several beneficial factors, the coincidence of which at the summit arises from interaction between seamount geomorphology, hydrodynamic regime, and water column structure. Neighbouring seamounts along the mid-ocean ridge are likely to present similarly complex oceanographic settings and, as with the SMS, associated sponge ground ecosystems may therefore be sensitive to changes over a particularly broad range of abiotic factors.

Full Citation

E.M. Roberts, F. Mienis, H.T. Rapp, U. Hanz, H.K. Meyer and A.J. Davies (2018) Oceanographic setting and short-timescale environmental variability at an Arctic seamount sponge ground, Deep-Sea Research Part I 138, 98-113. https://doi.org/10.1016/j.dsr.2018.06.007

Authors Accepted Manuscript

Download the Authors Accepted Manuscript here.

Publisher Version

See here.

Dataset Download

https://doi.org/10.1594/PANGAEA.891035

Optimising stocking density for the commercial cultivation of sea urchin larvae

Optimising stocking density for the commercial cultivation of sea urchin
larvae

Suckling CC, Terrey D, Davies AJ

Increased pressure on wild stocks of sea urchins had led to a requirement for aquaculture based production. However, effective and efficient methodologies still remain under development. The effects of stocking density on Psammechinus miliaris and Paracentrotus lividus were investigated in order to evaluate optimum stocking densities for large scale production. Larvae were reared at stocking densities of 1, 2, 3 and 4 larvae mL−1 and the effects on survival, development, abnormality and morphology were recorded. Additional cultures were maintained at a high density of 3 larvae mL−1 and then displaced to a lower density of 1 larvae mL−1 part way through the larval life cycle (‘displacement treatment’; day 13), to evaluate whether negative effects of high stocking densities could be mitigated. Responses from each species differed. P. miliaris demonstrated the highest growth at 1 larvae mL−1, resulting in larger larval and rudiment sizes by the end of the experiment (day 16). Rearing at 2 larvae mL−1 also demonstrated good growth performance, but only up to day 12. Higher densities of 3 and 4 larvae mL−1 did not affect survival or development, but significantly negatively impacted growth. There was no significant impact on survival, development, and morphology at any of the tested stocking densities for P. lividus. However, of note is that P. lividus reared at a high density of 4 larvae mL−1 had 25% lower survival than controls by the end of the experimental period (day 16). Displacement (larvae transferred from 3 to 1 larvae mL−1 on day 13) was effective for both P. miliaris and P. lividus with survival and rudiment sizes similar to larvae stocked continuously at low densities of 1 larvae mL−1. Although, P. lividus generally performed well at high densities, this demonstrates that displacement approaches could be possible for this species if required. However, of note is that displaced P. lividus had 30% lower survival than controls by the end of the experimental period (day 16). Therefore, this cultivation approach may be a generally viable option for large scale cultivation of these species. This study highlights that species responses can be different when reared at differing stocking densities highlighting a need to expand this approach to a wider range of marketable species. It also demonstrates that more efficient means of production (e.g. displacing larval densities part way through the production process) might be possible for some species (e.g. P. miliaris).

Full Citation

Suckling CC, Terrey D, Davies AJ (2018) Optimising stocking density for the commercial cultivation of sea urchin larvae, Aquaculture, 408: 96-104 DOI: 10.1016/j.aquaculture.2018.01.022

Link

https://doi.org/10.1016/j.aquaculture.2018.01.022

New Ascophyllum paper

Sex-specific reproductive trade-offs in the gregarious fucoid macroalga Ascophyllum nodosum

Kurr M, Davies AJ

The existence of sex-specific reproductive trade-offs is well established in plants. They usually occur because females invest more resources into reproduction than males, and have to compensate by sacrificing growth or defence. Investigations into by-sex differences in resource allocation by seaweeds are comparatively scarce. A small number of authors report differences between the sexes in some red algae, but known by-sex differences in brown algae are largely confined to the reproductive structures. In this study, sex-specific reproductive trade-offs are investigated in the common temperate brown alga Ascophyllum nodosum from three distinct populations. Quantified investments into growth, defence, and reproduction of a large number of individuals (n = 720) selected across a full annual cycle are presented in parallel with feeding trials using a common gastropod herbivore and a comprehensive assessment of the biotic and abiotic stressors impacting on A. nodosum at three sites. These reveal that sex-specific reproductive trade-offs occur in two of the three populations, as females invest more into reproduction than males and are subsequently less chemically defended for the months post gamete release. Feeding trials confirm that this leaves females more vulnerable to grazing pressure during these months, although mortality and competitive ability appear unaffected in the field. Possible causes of the trade-offs made by females are discussed, and new avenues of investigation are identified which could reveal interesting parallels between seaweeds and higher plants.

Full Citation

Kurr M, Davies AJ (2017) Sex-specific reproductive trade-offs in the gregarious fucoid macroalga Ascophyllum nodosum, European Journal of Phycology, DOI: 10.1080/09670262.2017.1328746

Link

http://www.tandfonline.com/doi/full/10.1080/09670262.2017.1328746

New paper in L&O

Tidal modulation of seabed light and its implications for benthic algae

Roberts EM, Bowers DG, Davies AJ

The temporal behavior of seabed light in a shallow, tidal sea is set largely by the interaction of the solar elevation cycle with tidal cycles in water depth and temporal variability in water clarity. The effect of tidal modulation on seabed light often does not simply average out, producing instead a net effect (either an amplification or a reduction of seabed light, integrated over time) compared to a tideless, but otherwise equivalent, scenario. Observations of this phenomenon from the Bay of Brest (France) show reasonable agreement with predictions based on an earlier theoretical framework, confirming that the key physics has been understood and that the important parameters are tidal amplitude, timing of low waters, diffuse attenuation coefficient, and daylength. Implications for benthic macroalgae living in the bay’s shallow subtidal zone are investigated using a simple numerical model. The effects of the tide on time-integrated seabed light and, in turn, time-integrated macroalgal community photosynthesis in the Bay of Brest correspond closely at three timescales: annual, springs-neaps (i.e., approximately fortnightly), and daily. Tidal amplification of both parameters occurs over the year, during winter months generally, and at spring tides during winter specifically (slight reduction occurs at neaps during winter). For an individual, isolated thallus, the relationship between tidal modulation of seabed light and photosynthesis is complicated by more pronounced light-saturation and photoinhibition effects. Demonstrated here for the first time, neglecting tidal effects on seabed light is likely to result in erroneous estimates (and, for many sites, underestimation) of subtidal benthic productivity.

Full Citation

Roberts EM, Bowers DG, Davies AJ (2017) Tidal modulation of seabed light and its implications for benthic algae. Limnology and Oceanography. doi:10.1002/lno.10616

Link

http://onlinelibrary.wiley.com/doi/10.1002/lno.10616/full