Down by the Water

The aqualung, introduced in the late 1940s, opened up new possibilities to explore marine life. Research on interactions of marine organisms with each other and the surrounding environment intensified, and marine ecosystem science was born. Since then, molecular tools, remote sensing techniques, advanced computer models, and statistical methods have provided new ways to investigate marine ecosystems and, during the last few decades, the understanding of marine ecosystems has increased exponentially (Paine 1969; Jackson and others 2001; Howarth and Marino 2006).

It is now clear that ecosystem dynamics and earth system processes are fundamentally shaped by human actions (Turner and others 1990; Rockström and others 2009). This new context, often referred to as a new geological era (the Anthropocene) is characterized by unprecedented connectivity between ecological and social domains, from local to global scales (Adger and others 2009; Walker and others 2009) and manifested by increasing speed in terms of extraction and flow of resources, activities, ideas, and information across geographic and jurisdictional scales (Folke and others 2011; Brondizio and others 2016). Such intertwined social and ecological processes also shape marine ecosystems. Hence, marine ecosystems are not only influenced by human actions, but rather, humans are increasingly becoming embedded parts of the dynamics and behavior of marine ecosystems (Fulton and others 2011; Glavovic and others 2015) in what we refer to as social-ecological systems (Berkes and Folke 1998). This new reality necessitates a re-evaluation of how marine ecosystems are perceived and studied as well as managed and governed.

Most, if not all, marine ecosystems are in some way connected to the globalized economy and often impacted by human activities at regional or global scales (Hoegh-Guldberg and Bruno 2010; Crona and others 2015; Gattuso and others 2015). Hence, human activities previously not considered to be of immediate relevance to marine scientists are now playing a most central role in shaping marine ecosystem dynamics worldwide (Norström and others 2016). For example, urbanization and consumption patterns influence prices, incentives, and activities in the seafood, agricultural, transport, tourism, and energy sectors, ultimately affecting resource extraction patterns and release of toxins, heavy metals, organic particles, and nutrients, or leading to the destruction of marine habitats (Figure 1). The new, and increasingly diverse ways in which actors at various scales, and in different sectors, interact with marine ecosystems is also challenging the capacity of institutions set up to govern the marine environment to adapt to rapid and non-linear social, economic, and technical change (Galaz and others 2016; Merrie and others 2014). Marine ecosystem science is confronted with a changing, and increasingly interconnected turbulent world.

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Marine ecosystem science on an intertwined planet. Changes in marine ecosystem dynamics are influenced by socioeconomic activities (for example, fishing, pollution) and human-induced biophysical change (for example, temperature, ocean acidification) and can interact and severely impact marine ecosystem dynamics and the ecosystem services they generate to society. Understanding these direct—or proximate—interactions is an important step towards sustainable use of marine ecosystems. However, proximate interactions are embedded in a much broader socioeconomic context where, for example, economy through trade and finance, human migration and technological advances, operate and interact at a global scale, influencing proximate relationships. These indirect—or distal—interactions add dimensionality and complexity to the global marine social-ecological system

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The social-ecological connectivity of marine ecosystems across geographic regions and between sectors is widespread (Deutsch and others 2007; Homer-Dixon and others 2015) with ‘teleconnected’ social-ecological dynamics across previously unconnected systems (Adger and others 2009; Liu and others 2015). This rising connectivity increases the likelihood of tipping points by reducing the ‘modularity’ of the system (Scheffer and others 2012) and as marine and terrestrial food production systems are increasingly intertwined, consequences for global food security, and resilience is largely unknown (Merino and others 2012; Troell and others 2014; Béné and others 2015). Fishing technologies and practice, mediated by political interests and globally operating actors, can spread rapidly across the planet (Norse and others 2012; Pauly and others 2013; Österblom and Folke 2015), sometimes at a speed and scale even resembling pathological disease dynamics (Eriksson and others 2015). Such novel cross-scale interactions represent new challenges for understanding marine ecosystem dynamics but also open new opportunities for stewardship of marine ecosystems, exemplified by global certification schemes (Jacquet and others 2010) and by actors in key positions in seafood value chains (Österblom and others 2015).

Little Fish: Three Emerging Mainstreams of Marine Ecosystem Science

Small fish are easier to catch than big fish. A decade of summer holiday gillnetting in the Baltic Sea may yield one individual cod Gadus morhua, whereas springtime handlining may yield hundreds of individual herring Clupea harengus. Anyone with proper equipment and basic knowledge can catch herring. However, smoking it to the perfect flavor and getting the right golden shine on the skin is proof of skills. Consuming this delicacy in perfect Swedish summer weather requires a bit of pure luck.

Here, we present three current research frontiers that represent emerging mainstream areas of marine ecosystem science. In the context of a globally intertwined planet, they exemplify ‘little fish’—easy to identify, requiring skills to refine, but not necessarily capturing key future challenges of marine ecosystem science.

Understanding Interacting Drivers of Change

An increasing understanding of complex and interacting changes in marine ecosystems has led scientists to move from studying species interactions towards focusing on non-linear interactions (Cury and others 2011), interacting drivers of change (Halpern and others 2008), or cascading effects in complex food webs (Frank and others 2005). Research on how climate variability and change, including ocean acidification, fundamentally influence species phenology, abundance, and distribution is gaining attention (Hoegh-Guldberg and Bruno 2010; Gattuso and others 2015) as well as how humans influence marine ecosystem dynamics through removal of predators and prey, altering of habitats, or by adding nutrients, toxins, and so on (Jackson and others 2001; Folke and others 2004; Eriksen and others 2014). Corresponding modeling efforts have moved from carbon budgets to models that incorporate complex ecological, biophysical, and chemical changes (Cheung and others 2009; Keeling and others 2010).

Identifying Thresholds in Ecosystems

Observational, experimental, and modeling studies have shown that many marine ecosystems are characterized by non-linear dynamics and thresholds (or tipping points), which if surpassed may cause systems to shift into alternative states or regimes (Hare and Mantua 2000; Scheffer and others 2001; Rocha and others 2015). The likelihood of such shifts increases with human actions that cause loss of resilience (Folke and others 2004; Österblom and Folke 2015). Because shifts to alternative states may imply significant losses of ecosystem services, much effort has been directed towards a better understanding of the location of tipping points (Biggs and others 2009), which can support ecosystem managers' ambitions to stay away from unexpected (unwanted) change or address feedback mechanisms that maintain ecosystems in degraded states and try to break them (Nyström and others 2012). Novel models are being developed to identify indicators that may signal approaching thresholds (Dakos and others 2015).

Investigating Social-Ecological Dynamics

Approaches to study marine ecosystems as components of truly integrated marine social-ecological systems (Berkes and Folke 1998; Perry and others 2011) range from research on how markets and incentives shape marine food webs (Ferrol-Schulte and others 2014) to the role of marine ecosystems for coastal livelihoods (Allison and Horemans 2006) and advanced social-ecological modeling (Lade and others 2015). Applications of the social-ecological lens to marine systems also includes work on adaptive responses to restore and improve marine ecosystems, such as increases in protected areas and novel frameworks, tools, and dynamic approaches for managing fisheries (Degnbol and McCay 2006; Branch 2009; Dunn and others 2016). Studies investigating how actors organize to improve ecosystem stewardship at various interacting geographical levels have grown substantially (Young and others 2007; Gelcich and others 2010) and novel methods are enabling an understanding of generic features of marine social-ecological systems across cultural, economic, and political contexts (Gutierrez and others 2011; Cinner and others 2012; Bundy and others 2015).

Big Fish: Moving Beyond Existing Frontiers

Big fish are generally more difficult to catch than small fish. Catching big fish can be intimidating, and killing and gutting them is not always fun. But ultimately it is a much bigger meal, and the reward is greater.

The new global context is resulting in a situation where marine ecosystem scientists are challenged to move beyond existing research frontiers. Studying more of the same easily leads to confirmation bias and limits the ability to think creatively about critical factors of marine ecosystem dynamics of an increasingly connected and unpredictable social-ecological future. Marine scientists should therefore be encouraged to venture out into the largely unexplored—to set their eyes on some ‘big fish’—three of which are outlined below.

Modeling the Anthropocene

Existing modeling efforts are already moving from species interactions, to fisheries–human interactions and ecosystem–social interactions (Hughes and others 2005). Important next steps will be to understand and incorporate the mechanisms behind the traditional “drivers of change” studied (Figure 1). What are the mechanisms driving change in industries and activities shaping marine ecosystems? For instance, how does urbanization or intensified land use lead to runoff and sedimentation changes, or disease spread in coastal marine ecosystems? How does aquaculture development reduce pressure on marine habitats and food webs, or how does conservation of species in one area, result in outsourcing of problems and ecosystem impacts elsewhere? Existing models and scenarios critically need to incorporate methods, theories, and approaches from adjoining disciplines to further understanding of marine systems in the new global context. Incorporating non-linear change, surprise, and cascading social-ecological dynamics represent additional key challenges.

Operationalizing Resilience

The concept of resilience, gaining attention in science, policy, and practice, is closely associated with research on thresholds and alternative states (Holling 1973; Scheffer and others 2001). Loss of resilience increases the likelihood of approaching thresholds. Progress has been made to understand and quantify marine ecosystem resilience (Nyström and others 2008), but understanding resilience of marine social-ecological systems remains a critical challenge. Work on general principles for building resilience in social-ecological systems (Biggs and others 2009) has raised the question of relevant indicators (Quinlan and others 2015). For social-ecological systems, resilience thinking incorporates interactions between slow and fast variables contributing to general and specified resilience (Folke and others 2010). What factors determine the adaptive capacity of species, ecosystems, and linked social-ecological systems and how can marine social-ecological systems build general resilience to deal with the new climate reality, the new globalized economy, and a truly intertwined social-ecological planet?

Understanding Social-Ecological Dynamics Across Scales

An integrated understanding of social-ecological dynamics can inform the scientific understanding of how human communities, nations, and regions adapt and respond to social-ecological change and how they may transform towards ecosystem-based approaches to marine management (Berkes 2012). Case studies of adaptive governance and system transformations have illustrated how global connectivity facilitates the rapid spread of ideas and governance approaches across regions, with possible global implications for how institutions at diverse geographical scales interact with ecosystems (Schultz and others 2015). These processes are often studied “from the outside” or in a historical perspective. Moving this research frontier forward may involve work where academics become embedded in change processes that are deliberately designed as experiments. Such strategically guided change processes would allow for systematic monitoring and evaluation to harvest new insights on adaptation and transformations in marine social-ecological systems. It needs to be stressed that an increased focus on enabling transformation does not in any way reduce the importance of an in depth understanding of marine ecosystem dynamics, but rather adds important components in order to investigate and understand social-ecological dynamics across scales.

Swimming in the Water: Scientific Strategies for Staying Ahead of the Game

Catching both small and big fish requires a stronger link between empirical research and theory, between interconnected dynamics of local and global scales, and between modeling and experimentation, but also incorporation of theories, models, data, and analytical methods from diverse disciplines. The latter will hopefully enable us to engage with questions that currently seem impossible to answer due to existing limitations in data or approaches. Below, we outline three broad strategies for scientists interested in developing capacity to move current research frontiers, big or small, forward.

Substantial social-ecological surprise and shocks are becoming the global norm—from climate change induced flooding, or financial crises impacting on food prices, to armed conflict and pervasive migration. Preparing for the unexpected is therefore a critical research strategy. Consequently, scientists, as well as policy makers and practitioners, need to be aware of, and prepare for, unexpected events that may originate outside traditional marine ecosystem science, and make this “unknown” part of the wider research and policy agenda.

The speed, scale, and connectivity outlined above requires an increased collaboration across disciplinary boundaries with “marine scientists” working in synergy with researchers from seemingly distant research areas such as nanotechnology, genetic engineering, artificial intelligence, gender and equity, or business administration and finance. Such collaboration can help identify novel ways to understand and govern marine ecosystems.

Finally, we must understand our cognitive limitations—the priorities described above have primarily emerged from North American, European, and Australian scientific communities—clearly not a representative sample of knowledge systems, world views, priorities, and attitudes. New scientific leadership may fundamentally change these outlined priorities.

There are dangers associated with doing something uncomfortable, but also rewards. Jumping in at the deep end of the pool is fun the first time you try it, but quickly becomes normal as you learn how to swim. Jumping into the water from ten meters above never gets old. It is completely terrifying every time: a short period of weightlessness and panic, followed by a sudden impact. It is exciting and not completely safe. We argue that the concept of the Anthropocene requires marine scientists to move outside traditional comfort zones – to take a big dive, a deep swim, and go for some big fish!