Aquatic Biodiversity and Ecosystems 2015 Liverpool

Louise B. Firth, Mieszkowska N, Grant LM, Bush LE, Davies AJ, Frost MT, Moschella PS, Burrows MT, Cunningham PN, Dye SR, Hawkins SJ

Biogenic reefs are important for habitat provision and coastal protection. Long-term datasets on the distribution and abundance of Sabellaria alveolata (L.) are available from Britain. The aim of this study was to combine historical records and contemporary data to (1) describe spatiotemporal variation in winter temperatures, (2) document short-term and long-term changes in the distribution and abundance of S. alveolata  and discuss these changes in relation to extreme weather events and recent warming, and (3) assess the potential for artificial coastal defense structures to function as habitat for S. alveolata . A semi-quantitative abundance scale (ACFOR) was used to compare broadscale, long-term and interannual abundance of S. alveolata  near its range edge in NW Britain. S. alveolata  disappeared from the NorthWales and Wirral coastlines where it had been abundant prior to the cold winter of 1962/1963. Population declines were also observed following the recent cold winters of 2009/2010 and 2010/2011. Extensive surveys in 2004 and 2012 revealed that S. alveolata  had recolonised locations from which it had previously disappeared. Furthermore, it had increased in abundance at many locations, possibly in response to recent warming. S. alveolata  was recorded on the majority of artificial coastal defense structures surveyed, suggesting that the proliferation of artificial coastal defense structures along this stretch of coastline may have enabled S. alveolata  to spread across stretches of unsuitable natural habitat. Long-term and broadscale contextual monitoring is essential for monitoring responses of organisms to climate change. Historical data and gray literature can be invaluable sources of information. Our results support the theory that Lusitanian species are responding positively to climate warming but also that short-term extreme weather events can have potentially devastating widespread and lasting eff ects on organisms. Furthermore, the proliferation of coastal defense structures has implications for phylogeography, population genetics, and connectivity of coastal populations.

 Patton RL, Richardson CA, Davies AJ, Chenery SRN

Anthropogenic activities since the industrial revolution in the Anthropocene have resulted in a progressive increase in atmospheric carbon dioxide (CO2 ). Approximately 30% of emitted CO2  has been absorbed by the world’s oceans, mitigating in some part the warming eff ect induced by increasing CO2 . This has resulted in a continuous decline in surface-ocean pH, which has decreased from 8.2 to 8.1 over the last 200 years. By the year 2100, mean surface-ocean pH is predicted to continue to fall to ⇠ 7.68. Concomitantly mean surface ocean temperatures are expected to rise by 2-4° C by the end of the century. An increase in seawater CO2  concentrations leads to a reduction in the concentration of carbonate ions, and the saturation states of major carbonate polymorphs (e.g. calcite and aragonite). As a result, calcifying organisms such as bivalve molluscs are considered especially vulnerable to the effects of ocean acidification (OA). We report on laboratory studies into the effects of ocean acidification and increases in ambient seawater temperature on the incremental growth, shell thickness, shell microstructure, and physiological condition of juvenile blue mussel, Mytilus edulis  and European common cockles, Cerastoderma edule  held under controlled conditions of tidal emersion and OA under a seasonal temperature cycle. 

 Suckling CC, Clark MS, Peck LS, Davies AJ

Our oceans are changing and will become undersaturated with respect to carbonates as CO2  increases. Organisms residing in temperate coastal environments may struggle to maintain homeostatic and biomineralising processes under these conditions. Current research needs in this field are those of long-term exposures to determine the sustainability of physiological flexibility/acclimation and energy requirements. We address these needs by presenting the responses of a slow-growing benthic invertebrate – the sea urchin, Psammechinus miliaris . These urchins were reared under IPCC forecasted carbonate saturation states and under present-day seasonal temperatures for long periods (several years) and their physiological, energetic and reproductive responses assessed. Additionally the next generation of urchins were reared under these conditions through to full maturation, an approach not previously utilised for marine macro invertebrates. We show that P. miliaris  can acclimate to laboratory conditions and this is sustained when exposure is extended to several years and across generations. We also see diff ering responses across generations such as seasonal disturbances. We show that different responses can be achieved from short/long term studies and across generations. Therefore careful consideration is needed when predicting organismal responses based from short-term data. This long-term study contributes significantly to our current understanding of organismal responses under a future climate.

Davies AJ, Strachan B

 

Physical disturbance is a localised but common occurrence on reefs formed by the polychaete worm Sabellaria alveolata. These reefs are an important example of habitats that elevate local diversity, but are found in highly dynamic environments that can be heavily impacted by disturbance from waves and human trampling. Several experiments were conducted on reefs at Llanddulas, North Wales, using an approach to simulate recurrent disturbance in a quantifiable and repeatable way. Three weights (5.3, 2.7 and 0.5 kg) were dropped from a set height (1.5 m) over three timescales (daily, fortnightly and once a month), followed by a fortnightly survey for a further month to assess the recovery of the structure. Exposure to a daily impact from a 5.3 kg weight destroyed the reef structure, with no recovery in the following month but lesser impact force (0.5 kg) showed recovery and continued persistence. Disturbance on larger Sabellaria alveolata structures, for example 20 cm from the edge of a large reef, demonstrated greater resilience to damage than impact at the edge of the reef. Repeated impact from high forces drives substantial decline in the persistence of S. alveolata reef, we must reduce impact where possible, such as from avoidable human trampling.

Bush LE, Balestrini SJ, Robins PE, Davies AJ

Within Europe, the honeycomb reef worm, Sabellaria alveolata, is protected in its adult form as a habitat forming species. Like many coastal benthic invertebrates, S. alveolata feature a complex life-cycle, with a planktonic larval stage, in addition to a sessile bottom dwelling juvenile and adult stage. Populations of this biogenic reef forming species show variability on a short-term small-scale but persistence on a long-term broad-scale. This pattern of short-term small-scale change is largely driven by settlement success. We monitored fecundity in adult worms and larval abundance offshore, from three known Abundant sites (Dunraven, Aberarth, and Llanddulas) on a latitudinal gradient within Wales, monthly from March to September 2014. We also modelled predicted larval dispersal from numerous Abundant sites over a large spatial scale on the west coast of the UK, using a high resolution hydrodynamic model combined with a passive Lagrangian Particle Tracking Model. Poorly synchronised seasonal spawning was demonstrated, with regional temporal differences. Larval source and sink sites were identified, with connectivity between regional populations predicted, but limited between regions, specifically (i) north Devon and Cornwall; (ii) South Wales; (iii) Cardigan Bay and (iv) North Wales and northeast England. Predicted dispersal north of the current range limit was minimal.

 Bush LE, Yesson C, Maggs CA, Brodie J, Hawkins SJ, Davies AJ

The large brown seaweeds (macroalgae) are keystone species in both the intertidal and subtidal marine environments. Recently there have been several reports of changes in abundance in these species, within the northeast Atlantic. We assessed the changes in abundance of large brown seaweeds from historic survey data, in addition to oblique intertidal imagery. Species specific data were analysed for fourteen species of large brown macro algae from the 1970s to the 2010s. Regional changes in abundance were demonstrated, with significant declines in abundance in the south for kelp species, and increases in northern and central regions for some species of kelp and wracks. Additionally change was assessed in a relative index of cover of large brown seaweeds, from sequential oblique imagery collected on rocky shores of the Isle of Man from the 1980s to the 2010s. A cyclic pattern of change through time was demonstrated when large brown macroalgae were considered as a functional group.

D’Urban Jackson TB, Walker-Springett GR, Jones JM, Davies AJ

The UK holds a great diversity of intertidal habitats, many of which are features of protected areas. Understanding and managing natural intertidal features for biodiversity conservation and coastal protection requires fast, effective and repeatable monitoring. Using traditional techniques such as quadrat surveys to achieve this is can be labour intensive and expensive, and often relies on significant levels of expert knowledge that may not be present or consistent over long time series. Here, we demonstrate terrestrial laser scanning (TLS) as an effective tool to detect and monitor fine scale change in the 3D structure of an intertidal Sabellaria alveolata reef habitat. Regular (4 – 8 week) surveys were conducted of a 1200m2 area of reef at Llanddulas, North Wales over 6 months (August 2014 – February 2015). Change in the reef structure due to growth and erosion was detected on a millimetre to centimetre scale with high confidence. Natural variation in reef topography was quantified, and correlations were observed between change in elevation and physical morphological factors such as rugosity and reef block height. This study demonstrates that TLS is a robust, repeatable and cost-effective tool to monitor the physical structure of dynamic intertidal habitats.