Indexing habitat opportunity for juvenile anadromous fishes in tidal-fluvial wetland systems

Roegner, G. Curtis; Johnson, Gary E.; Coleman, André M.

doi:10.1016/j.ecolind.2021.107422

Cited by 5 publications

(2 citation statements)

References 32 publications

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“…This supports the notion that wetland restoration is a viable management strategy to aid the dwindling coastal pike stock and ultimately restore the function and services of the Baltic coastal ecosystem through top-down control of the food-web (Nilsson et al, 2014;Donadi et al, 2017;Greszkiewicz et al, 2022). Moreover, wetlands do not only constitute a key habitat for the viability of a plethora of species, including many fish, amphibian, bird and plant species, but is also central for the hydrology, water quality and nutrient cycling of aquatic systems (Kingsford et al, 2016;Tamario et al, 2019;Roegner et al, 2021). Unfortunately, the biological function of the majority of wetlands are impaired by, for instance, dredging to facilitate irrigation, agriculture and exploitation, with dramatic negative consequences both for biodiversity and the function and services of ecosystems (Davidson, 2014;Kingsford et al, 2016).…”

Section: Discussionmentioning

confidence: 72%

Higher abundance of adult pike in Baltic Sea coastal areas adjacent to restored wetlands compared to reference bays

et al. 2023

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The abundance of pike, a keystone top-predator, have declined dramatically in the Baltic Sea since the 1990s likely owing to recruitment failure. It has been proposed that wetland restoration can aid the recovery of the pike stock by increasing the number of recruits produced by anadromous populations. Yet, no previous studies have addressed whether wetland restorations are associated with higher abundances of adult pike in the coastal habitat. To address this, we performed standardised rod-and-reel survey fishing in paired bays with and without wetlands across three coastal areas and 3 years. To estimate dispersal and the contribution of wetland pike to the coastal stock, we tagged captured pike with passive integrated responders (PIT) and employed PIT reader stations in wetland inlets. The results showed that pike abundances were on average 90% higher in bays with an adjacent wetland although the effect varied among areas. Moreover, PIT-data uncovered that wetland pike constituted a high proportion of the pike found in adjacent coastal habitats and that some wetland fish dispersed up to 10 km. These results support that wetland restoration is a valuable tool to aid the coastal pike stock and ultimately restore the function and services of the coastal ecosystem.

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Section: Discussionmentioning

confidence: 72%

Higher abundance of adult pike in Baltic Sea coastal areas adjacent to restored wetlands compared to reference bays

et al. 2023

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“…Note for example that WES is linearly related to metabolic rate in our static model but requires a power function when considering a wider temperature range. Such a model could investigate the importance of wetland subsidies to other salmon populations in a more holistic matter, e.g., [74].…”

Section: Wetland Energy Subsidymentioning

confidence: 99%

Export of macroinvertebrate prey from tidal freshwater wetlands provides a significant energy subsidy for outmigrating juvenile salmon

Roegner

Johnson

2023

PLoS ONE

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Tidal freshwater wetlands linking terrestrial, riverine, and saline habitats are critical areas for material processing and exchange. Once historically widespread, herbaceous marsh and forested tidal freshwater wetlands especially are now highly degraded worldwide. Additionally, quantitative assessments of hydrology and material exchange from these systems are lacking compared to lotic and estuarine (saltmarsh) habitats. Here we investigate macroinvertebrate and energy export from tidal marsh and forested wetlands and consider potential benefits from this ecological process to endangered Pacific salmon in a large tidal freshwater system, the Columbia River (USA). Macroinvertebrate (salmon prey) concentration, water velocity, and discharge were measured at several wetland habitat types (forested swamp, emergent marsh, and restored marsh). We used these data to compute prey flux and transport metrics. Then, applying literature values to calculate prey energy equivalents and juvenile salmon metabolic requirements, we estimated the potential energy subsidy available to juvenile salmon. Numerically, larval stages of aquatic insects were the predominant type of prey exported from the wetlands, with Diptera chironomid fly abundance exceeding other groups. Energetically, however, non-chironomid dipterans and hemipteran prey comprised most of energy transport due to their higher energetic content (energy density × mean weight). We determined the prey energy transported from the sampled tidal channels was sufficient to meet energetic needs of tens to thousands of juvenile salmon per day, depending on prey production and hydrography. The prey taxonomic composition differed among organisms exiting forested swamp, emergent marsh, and restored marsh habitats with corresponding differences in energy transport, but all habitat types supported similar numbers of juvenile salmon. We conclude that macroinvertebrate prey exported from varied tidal freshwater wetlands likely provide significant benefits to juvenile salmon over a larger ecological footprint than the wetland area would suggest.

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Shallow-Water Habitat in the Lower Columbia River Estuary: A Highly Altered System

Templeton,

Jay,

Diefenderfer

et al. 2023

Estuaries and Coasts

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Decreases in shallow-water habitat area (SWHA) in the Lower Columbia River and Estuary (LCRE) have adversely affected salmonid populations. We investigate the causes by hindcasting SWHA from 1928 to 2004, system-wide, based on daily higher high water (HHW) and system hypsometry. Physics-based regression models are used to represent HHW along the system as a function of river inflow, tides, and coastal processes, and hypsometry is used to estimate the associated SWHA. Scenario modeling is employed to attribute SWHA losses to levees, flow regulation, diversion, navigational development, and climate-induced hydrologic change, for subsidence scenarios of up to 2 m, and for 0.5 m fill. For zero subsidence, the system-wide annual-average loss of SWHA is 55 ± 5%, or 51 × 105 ha/year; levees have caused the largest decrease ($${54}_{-14}^{+5}$$ 54 - 14 + 5 %, or ~ 50 × 105 ha/year). The loss in SWHA due to operation of the hydropower system is small, but spatially and seasonally variable. During the spring freshet critical to juvenile salmonids, the total SWHA loss was $${63}_{-3}^{+2}$$ 63 - 3 + 2 %, with the hydropower system causing losses of 5–16% (depending on subsidence). Climate change and navigation have caused SWHA losses of $${5}_{-5}^{+16}$$ 5 - 5 + 16 % and $${4}_{-6}^{+14}$$ 4 - 6 + 14 %, respectively, but with high spatial variability; irrigation impacts have been small. Uncertain subsidence causes most of the uncertainty in estimates; the sum of the individual factors exceeds the total loss, because factors interact. Any factor that reduces mean or peak flows (reservoirs, diversion, and climate change) or alters tides and along-channel slope (navigation) becomes more impactful as assumed historical elevations are increased to account for subsidence, while levees matter less.

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Indexing habitat opportunity for juvenile anadromous fishes in tidal-fluvial wetland systems

Cited by 5 publications

References 32 publications

Higher abundance of adult pike in Baltic Sea coastal areas adjacent to restored wetlands compared to reference bays

Higher abundance of adult pike in Baltic Sea coastal areas adjacent to restored wetlands compared to reference bays

Export of macroinvertebrate prey from tidal freshwater wetlands provides a significant energy subsidy for outmigrating juvenile salmon

Shallow-Water Habitat in the Lower Columbia River Estuary: A Highly Altered System

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