Managing aquatic habitat structure for resilient trophic interactions

Abstract

Structural habitat (the three-dimensional arrangement of physical matter, abiotic and biotic, at a location) is a foundational element for the resilience and maintenance of biodiversity, yet anthropogenic development is driving the global simplification of aquatic environments. Resource managers regularly seek to conserve aquatic food webs by increasing structural habitat complexity with expected benefits to fisheries; however, the global effectiveness of such actions is unclear. Our synthesis and theoretical analyses found that the response of a consumer-resource interaction (predatory sportfish and forage fish prey) to the addition of prey refuge habitat differed among systems with low and high rates of biomass transfer from resource to consumer (i.e., biomass potential); stabilization was not the rule. Greater prey refuge habitat availability tended to stabilize systems characterized by high biomass potential while simultaneously increasing consumer densities. In contrast, increasing prey refuge habitat availability in systems characterized by low biomass potential tended to mute energy transfer and moved consumer densities toward local extinction.Importantly, biomass potential and prey refuge can have antagonistic effects on stability and relative consumer densities, and it is therefore important to consider the local conditions of a system when using habitat manipulation as a management measure. Further development of our context-dependent perspective to whole food webs, and across different environments, may help to guide structural habitat management to better restore and protect aquatic ecosystems.

Landscape diversity promotes stable food‐web architectures in large rivers

“…Revealing life's "devious strategies" that underpin the persistence and stability of food webs is a long-standing endeavour in ecology (Rooney & McCann, 2012) and has emerged as a key conservation priority (May, 2009;McDonald-Madden et al, 2016). Although many studies have documented connections between biodiversity and food-web stability (McCann, 2000), the influence of physical habitat in modulating these connections has only recently come into focus (Ward et al, 2023). Revealing the ways in which nature's stage (sensu Lawler et al, 2015) shapes food-web dynamics is a frontier in food-web ecology, and pioneering syntheses (Polis et al, 1997) and theoretical models (McCann, 2012;Rooney et al, 2008) have provided the groundwork for observational studies, such as ours, to validate and improve our understanding of connections between the landscape and the persistence of biodiversity.…”

The impact of climate change on piracema and the sustainability of aquatic resources

“…Paradoxically, while the quest for ideal spawning grounds becomes more challenging, increased rainfall intensifies the risks associated with extreme weather events, such as sudden floods and abrupt variations in water levels, imposing additional obstacles to upstream migration (Das et al, 2012;Patrick et al, 2016). This complex panorama of climate change reverberates through the intricate trophic web of river ecosystems, as fish populations face adversities, and organism's dependent on their presence as a primary food source, along with predators at higher trophic levels, are confronted with feeding challenges and the need to recalibrate their ecological niches (Sabo et al, 2009;Ward et al, 2023).…”