Larissa A. Naylor

Biogeomorphology revisited: looking towards the future

Although biogeomorphological research is well-established, with many studies on a range of two-way interrelations between organisms and geomorphology in different environments, there is little consensus over what constitutes biogeomorphology, why it might be useful and where it is heading. Starting with definitions of core biogeomorphic processes, we consider the need for future biogeomorphological studies to evaluate the crucial links between bioprocesses, biological community dynamics and ‘inorganic’ earth surface processes. Five key applications of biogeomorphological research are identified; the roles of organisms in environmental reconstruction, trace fossil analysis, extraterrestrial geomorphology, environmental engineering and the built environment. Some key research directions and methodological challenges for future biogeomorphological research include expanding the spatial and temporal coverage of datasets, investigating the role of bioprocesses in landform development, tackling scale issues, investigating the relevance of nonlinear dynamical ideas to biogeomorphology and developing better sampling and monitoring techniques for bioprocesses.

A new technique for evaluating short-term rates of coastal bioerosion and bioprotection

A multi-scale and multi-method approach has been developed to evaluate the nature and effects of short-term biological colonisation. This method has been used at Falasarna, on the western coast of Crete, to investigate bioprotection and bioerosion on a microtidal rocky coast. Eighteen blocks of limestone (5×5×2 cm) were exposed for 7 months (September 1998 to April 1999) at mean sea level at two exposed sites and one sheltered site. Biological colonization and its impacts were assessed by optical microscopy (OM), scanning electron microscopy (SEM) and multiphoton laser scanning microscopy (MPLSM). Exposed sites became colonized more quickly than the sheltered site and once a cover of foliose and filamentous algae had become established, bioerosion (by cyanobacteria), biological etching and chemical weathering were reduced. Consequently, there appears to be an inverse relationship between macroalgal abundance and bioerosion of experimental substrata after 7 months of colonisation. Thus, some level of bioprotection appears to be provided by macro algae under exposed site conditions and would probably become increasingly apparent in longer-term research trials.

Stormy geomorphology: geomorphic contributions in an age of climate extremes

The increasing frequency and/or severity of extreme climate events are becoming increasingly apparent over multi‐decadal timescales at the global scale, albeit with relatively low scientific confidence. At the regional scale, scientific confidence in the future trends of extreme event likelihood is stronger, although the trends are spatially variable. Confidence in these extreme climate risks is muddied by the confounding effects of internal landscape system dynamics and external forcing factors such as changes in land use and river and coastal engineering. Geomorphology is a critical discipline in disentangling climate change impacts from other controlling factors, thereby contributing to debates over societal adaptation to extreme events. We review four main geomorphic contributions to flood and storm science. First, we show how palaeogeomorphological and current process studies can extend the historical flood record while also unraveling the complex interactions between internal geomorphic dynamics, human impacts and changes in climate regimes. A key outcome will be improved quantification of flood probabilities and the hazard dimension of flood risk. Second, we present evidence showing how antecedent geomorphological and climate parameters can alter the risk and magnitude of landscape change caused by extreme events. Third, we show that geomorphic processes can both mediate and increase the geomorphological impacts of extreme events, influencing societal risk. Fourthly, we show the potential of managing flood and storm risk through the geomorphic system, both near‐term (next 50 years) and longer‐term. We recommend that key methods of managing flooding and erosion will be more effective if risk assessments include palaeodata, if geomorphological science is used to underpin nature‐based management approaches, and if land‐use management addresses changes in geomorphic process regimes that extreme events can trigger. We argue that adopting geomorphologically‐grounded adaptation strategies will enable society to develop more resilient, less vulnerable socio‐geomorphological systems fit for an age of climate extremes.

A temperate reef builder: an evaluation of the growth, morphology and composition of Sabellaria alveolata (L.) colonies on carbonate platforms in South Wales

Abstract Sabellaria alveolata (Linné) (Polychaeta: sabellariidae) is a sedentary polychaete that builds wave-resistant reefs from sand-sized particles. Reefs are formed in areas with a large, continuous supply of sand-sized sediment and turbulent water, such as the Bristol Channel, UK. Although several studies have documented the extent, growth, form and geological importance of Sabellariidae, their bioconstructive role has not been adequately assessed. S. alveolata occurs rarely in the UK and is classified as a distinct ecological unit by the Marine Nature Conservation Review, yet it has been little studied. Thus, there is a need for greater understanding of the species’ role in UK coastal ecology and geomorphology. An evaluation of reef development in terms of composition, growth and extent of S. alveolata constructions on carbonate shore platforms in South Wales is presented here. Results indicate that S. alveolata is a fast-growing species capable of juvenile settlement, tube formation and growth of 2.5–5.0 cm in as little as two months after installation of exposure blocks of artificial substrata. Particle size analysis of 24 randomly selected reefs and ten adjacent sand samples shows a significant difference in mean grain size, with worms consolidating particles of a coarser size distribution than the mean particle size of surrounding sand. Preliminary scanning electron microscope observations indicate preferential use of flat, platy and elongate particles in the worm tubes. This research forms part of a larger study concerned with quantifying the bioconstructive capability of S. alveolata.

Transformation in a changing climate: a research agenda

The concept of transformation in relation to climate and other global change is increasingly receiving attention. The concept provides important opportunities to help examine how rapid and fundamental change to address contemporary global challenges can be facilitated. This paper contributes to discussions about transformation by providing a social science, arts and humanities perspective to open up discussion and set out a research agenda about what it means to transform and the dimensions, limitations and possibilities for transformation. Key focal areas include: (1) change theories; (2) knowing whether transformation has occurred or is occurring; (3) knowledge production and use; (4) governance; (5) how dimensions of social justice inform transformation; (6) the limits of human nature; (7) the role of the utopian impulse; (8) working with the present to create new futures; and (9) human consciousness. In addition to presenting a set of research questions around these themes the paper highlights that much deeper engagement with complex social processes is required; that there are vast opportunities for social science, humanities and the arts to engage more directly with the climate challenge; that there is a need for a massive upscaling of efforts to understand and shape desired forms of change; and that, in addition to helping answer important questions about how to facilitate change, a key role of the social sciences, humanities and the arts in addressing climate change is to critique current societal patterns and to open up new thinking. Through such critique and by being more explicit about what is meant by transformation, greater opportunities will be provided for opening up a dialogue about change, possible futures and about what it means to re-shape the way in which people live.

Chapter 17 Synthesis and conclusion to the rock coast geomorphology of the world

Rock coasts have long been a neglected landform, overlooked by researchers in favour of other systems such as beaches and dunes. The regional synthesis presented in this volume indicates that coastal researchers have embraced this geomorphic system, and while the number of people working on rock coasts may not be as high as other coastal fields, rock coasts can no longer be considered neglected landforms (cf. Trenhaile 1980; Stephenson 2000). The scale and detail of analysis presented in this volume highlights regional variations in research intensity over the past century. Some of the earliest descriptions of rock coasts were by Charles Darwin during the voyage of the Beagle (1831–1836) and James Dwight Dana during the US Exploring expedition (1838–1842) (see Chapters 13–15, Dickson & Stephenson 2014; Kennedy 2014; Woodroffe 2014). These two researchers set the scene for rocky shore research. Morphological descriptions of rock coasts then dominated research until the twentieth century when technological advances allowed precise data to be collected. In the early part of the twentieth century surveying techniques were applied to rock coasts globally; this enabled precise measurements of platform elevation, gradient and width of platforms. Wave flume experiments were conducted intensively in Japan (Sunamura 1992; Chapter 12, Sunamura et al. 2014) and to a lesser extent in Australia (Chapter 14, Kennedy 2014) during the 1960s and 1970s; however this approach is seldom used today. The 1970s saw further advances with the advent of the micro-erosion meter. It enabled researchers to quantify millimetre-scale change on rock surfaces (see Hansom et al. 2008 for a recent exception); early work was focused in the tropics, the UK (Chapter 4, Moses 2014) and New Zealand (Chapter 13, Dickson & Stephenson 2014). The greatest technological advances have occurred in the late twentieth century with the miniaturization …

Chapter 1 Introduction to the rock coasts of the world

Rock coasts are erosional environments which form as a result of the landward retreat of bedrock at the shoreline. Vertical faces plunging into deep water form imposing cliffs on many shorelines. Other cliff forms may be steeply sloping, but no strict definition delineates a slope from a cliff. In many instances the retreat of the cliff leads to the formation of a rock ledge, or shore platform, at or close to sea-level. The surface of these platforms may be either subhorizontal or slope gently in a seaward direction. Rock coasts have been considered a neglected coastal landform (Trenhaile 1980, 2002; Stephenson 2000). The two seminal books on the topic (Trenhaile 1987; Sunamura 1992) were written over two decades ago and they still form a core academic source which people refer to when seeking to understand the morphology and dynamics of rocky coasts. In the past decade there has been growing interest in rock coasts; however, the subdiscipline is still in its infancy when compared with other landform systems such as sandy beaches, rivers or glaciers. Much of the recent research is focused on a case-study approach, with small teams of researchers using their local field sites to infer wider morphological models of platform or cliff systems. A major driver for the growing interest in the rocky coast has been the advent of new and emerging technology that enables us to address problems not previously accessible and at scales not previously achievable. In the late nineteenth and early twentieth centuries scientific investigation was observational and lacked quantitative data (Dana 1849; Bartrum 1926). Such qualitative descriptions of the rocky coast continued into the mid twentieth century, when quantitative data from field surveying became the norm. The use of techniques for measuring rock hardness, such as the Schmidt hammer, …

Wave transformation across a macrotidal shore platform under low to moderate energy conditions

We investigate how waves are transformed across a shore platform as this is a central question in rock coast geomorphology. We present results from deployment of three pressure transducers over four days, across a sloping, wide (~200 m) cliff-backed shore platform in a macrotidal setting, in South Wales, United Kingdom. Cross shore variations in wave heights were evident under the predominantly low to moderate (significant wave height < 1.4 m) energy conditions measured. At the outer transducer 50 m from the seaward edge of the platform (163 m from the cliff) high tide water depths were 8+ m meaning that waves crossed the shore platform without breaking. At the mid platform position water depth was 5 m. Water depth at the inner transducer (6 m from the cliff platform junction) at high tide was 1.4 m. This shallow water depth forced wave breaking, thereby limiting wave heights on the inner platform. Maximum wave height at the middle and inner transducers were 2.41 and 2.39 m respectively and significant wave height 1.35 m and 1.34 m respectively. Inner platform high tide wave heights were generally larger where energy was up to 335% greater than near the seaward edge where waves were smaller. Infragravity energy was less than 13% of the total energy spectra with energy in the swell, wind and capillary frequencies accounting for 87% of the total energy. Wave transformation is thus spatially variable and is strongly modulated by platform elevation and the tidal range. While shore platforms in microtidal environments have been shown to be highly dissipative, in this macro-tidal setting up to 90% of the offshore wave energy reached the landward cliff at high tide, so that the shore platform cliff is much more reflective.

Stormy geomorphology: an introduction to the Special Issue

The degree to which the climate change signal can be seen in the increasing frequency and/or magnitude of extreme events forms a key part of the global environmental change agenda. Geomorphology engages with this debate through extending the instrumental record with palaeogeomorphological research; studying resilience and recovery of geomorphic systems under extreme disturbance; documenting the mediation by catchment organisation of transport processes during extreme events; applying new monitoring methods to better understand process-response systems; and illustrating how process, experimental and modelling insights can be used to define the buffering of geomorphic systems and human assets from the effects of extremes, providing practical outcomes for practitioners. This article is protected by copyright. All rights reserved.

How can we improve understanding of faecal indicator dynamics in karst systems under changing climatic, population, and land use stressors? – Research opportunities in SW China

Human exposure to water contaminated with faeces is a leading cause of worldwide ill-health. Contaminated water can be transmitted rapidly in karst terrain as a result of the connectivity of surface and groundwater systems, high transmissivity of aquifers over large areas, and well-developed underground conduit systems. Faecal indicator organisms (FIOs) are the most widely-used indicator of faecal contamination and microbial water quality; however, the conceptualisation of FIO risk and associated sources, pathways, and survival dynamics of FIOs in karst landscapes requires a degree of modification from traditional conceptual models of FIO fate and transfer in non-karst systems. While a number of reviews have provided detailed accounts of the state-of-the-science concerning FIO dynamics in catchments, specific reference to the uniqueness of karst and its influence on FIO fate and transfer is a common omission. In response, we use a mixed methods approach of critical review combined with a quantitative survey of 372 residents of a typical karst catchment in the southwest China karst region (SWCKR) to identify emerging research needs in an area where much of the population lives in poverty and is groundwater dependent. We found that the key research needs are to understand: 1) overland and subsurface FIO export pathways in karst hydrology under varying flow conditions; 2) urban and agricultural sources and loading in mixed land-use paddy farming catchments; 3) FIO survival in paddy farming systems and environmental matrices in karst terrain; 4) sediment-FIO interactions and legacy risk in karst terrain; and 5) key needs for improved hydrological modelling and risk assessment in karst landscapes. Improved knowledge of these research themes will enable the development of evidence-based faecal contamination mitigation strategies for managing land and water resources in the SWCKR, which is highly vulnerable to climate change impacts on water supply and quality of water resources.