True Value of Estuarine and Coastal Nurseries for Fish: Incorporating Complexity and Dynamics

Abstract

Coastal ecosystems, such as estuaries, salt marshes, mangroves, and seagrass meadows, comprise some of the world's most productive and ecologically significant ecosystems. Currently, the predominant factor considered in valuing coastal wetlands as fish habitats is the contribution they make to offshore, adult fish stocks via ontogenetic migrations. However, the true value of coastal nurseries for fish is much more extensive, involving several additional, fundamentally important ecosystem processes. Overlooking these broader aspects when identifying and valuing habitats risks suboptimal conservation outcomes, especially given the intense competing human pressures on coastlines and the likelihood that protection will have to be focussed on specific locations rather than across broad sweeps of individual habitat types. We describe 10 key components of nursery habitat value grouped into three types: 1) Connectivity and population dynamics (includes connectivity, ontogenetic migration and seascape migration), 2) Ecological and ecophysiological factors (includes ecotone effects, ecophysiological factors, food/predation trade-offs and food webs), and 3) Resource dynamics (includes resource availability, ontogenetic diet shifts and allochthonous inputs). By accounting for ecosystem complexities and spatial and temporal variation, these additional components offer a more comprehensive account of habitat value. We explicitly identify research needs and methods to support a broader assessment of nursery habitat value. We also explain how, by better synthesising results from existing research, some of the seemingly complex aspects of this broader view can be addressed efficiently.

Resilience of estuarine phytoplankton and their temporal variability along salinity gradients during drought and hypersalinity

“…The overall importance of estuaries in their protection and hosting of juvenile marine fish, post-larva prawns and other planktonic organisms have been noted previously (e.g. Whitfield, 1988;Sheaves et al, 2014). The importance of estuaries in general as high productivity regions, the results from previous studies on Lake St. Lucia and the importance of phytoplankton as one of the main providers of energy at the base of the food web (Fielding et al, 1991;Ramdani et al, 2009) prompted this study.…”

Climate mediates hypoxic stress on fish diversity and nursery function at the land–sea interface

“…These services include supporting biodiversity (7) and the provision of nursery habitat for species, where estuaries can contribute disproportionately to offshore fisheries productivity (8,9). The nursery function, in particular, could be affected by a suite of anthropogenic stressors, manifesting in declines to offshore fisheries production.…”

Response of Gilthead Seabream (Sparus aurata L., 1758) Larvae to Nursery Odor Cues as Described by a New Set of Behavioral Indexes

“…The value of nursery areas relies on a series of components that set their biological relevance, namely those components pertaining to connectivity and population dynamics (connectivity, ontogenic migration, seascape migration), ecological and ecophysiological factors (ecotone effects, ecophysiological factors, food/predation trade-offs, food webs), and resource dynamics (resource availability, ontogenic diet shifts, allochthonous inputs) (Sheaves et al, 2015). Therefore, the ability of species to respond to the intrinsic complexity of this ecosystem framework is vital for them.…”