Modeling the effect of water level on the Nueces Delta marsh community

Montagna, Paul A.; Sadovski, Alexey; King, Scott A.; Nelson, Kevin; Palmer, Terence A.; Dunton, Kenneth H.

doi:10.1007/s11273-017-9547-x

Cited by 10 publications

(5 citation statements)

References 26 publications

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“…To improve the marsh, salinity should be maintained between 6 and 18, minimum water depth should be between 0.2-0.3 m, and to improve ecological stability inflows should be continuous, not a pulsed flood (Montagna et al 2018a). But this is not likely to occur, and under current climate and water management conditions, the marsh will degrade further (Montagna et al 2017).…”

Section: 'Smentioning

confidence: 99%

How a Simple Question About Freshwater Inflow to Estuaries Shaped a Career

Montagna¹

2021

GCR

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Chance and good luck led to a career studying how freshwater inflow drives estuary processes. In 1986, someone asked me: How much fresh water has to flow to a bay for it to be healthy? The question shaped my career. There is probably no better place on Earth to compare effects caused by inflow differences than the Texas coast, because the major estuarine systems lie in a climatic gradient where runoff decreases 56—fold from the Louisiana border in the northeast to the Mexico border in the southwest. This estuary—comparison experiment was used to study inflow effects. The science evolved from the idea in the 1990’s that organisms responded directly to inflow rates to the domino theory in the 2000’s of indirect effects where inflow drives estuary conditions and that organisms respond to those habitat conditions. Today it is hypothesized that climate drives hydrology, which drives estuary dynamics; and thus, climatic factors can indirectly shape estuarine structure and function. Assuming change along the inflow gradient is analogous to effects of altering estuaries over time, we can now predict ecosystem change with changing climate or land—use change.

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Section: 'Smentioning

confidence: 99%

How a Simple Question About Freshwater Inflow to Estuaries Shaped a Career

Montagna¹

2021

GCR

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“…Inflow creates different salinity zone habitats within bays (Montagna et al 1996, and thus the critical need is to characterize within bay dynamics, not bay-wide dynamics. In addition, we now know that minimal inflow during dry times would minimize a bay system from degrading during droughts (Palmer and Montagna 2015;Montagna et al 2017).…”

Section: Freshwater Inflow Needsmentioning

confidence: 99%

“…Therefore, these areas need much less water to maintain an estuarine salinity zone that would maintain these natural nurseries. A model of the Nueces Delta marsh predicts reductions in plant cover in both drought and moderate conditions, and marsh plant coverage increases only during wet conditions (Montagna et al 2017). The delta marshes near river mouths are typically composed of a community of marsh plants, such as Batis maritima, Distichlis spicata, Monanthcloe littoralis, Salicornia virginica, Borrichia frutescens, and Spartina alterniflora (Montagna et al 2017).…”

Section: Freshwater Inflow Needsmentioning

confidence: 99%

“…A model of the Nueces Delta marsh predicts reductions in plant cover in both drought and moderate conditions, and marsh plant coverage increases only during wet conditions (Montagna et al 2017). The delta marshes near river mouths are typically composed of a community of marsh plants, such as Batis maritima, Distichlis spicata, Monanthcloe littoralis, Salicornia virginica, Borrichia frutescens, and Spartina alterniflora (Montagna et al 2017). These marshes are distinct from fringing marshes that are composed of only Spartina alterniflora and occur throughout the bay systems, including the primary bays.…”

Section: Freshwater Inflow Needsmentioning

confidence: 99%

“…Focused flows from water transactions could also be created by mitigation or restoration actions, or a permanent water right. Part of the economic value generated by a more rapid recovery from extreme droughts using a focused flow regime-where natural nurseries are maintained-can be calculated by the increase in the rate of recovery of habitat and infauna and epifauna communities (Montagna et al 2018;Montagna et al 2017) and commercially and recreationally important fish recovery (Lellis-Dibble et al 2008;Brown et al 2018). Thus, focused flows is an economically useful strategy for restoration projects.…”

Section: One Potential Solution: Focused Flowsmentioning

confidence: 99%

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Focused Flows to Maintain Natural Nursery Habitats

Montagna

McKinney

Yoskowitz

2021

Texas Water Journal

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Regulatory standards for environmental flows to estuaries are not common, but they are required in Texas. This has led to adoption of complex freshwater inflow regimes that reflect seasonal and yearly fluctuations that vary geographically throughout the state. The flow regimes are based on dilution of saline water with fresh water in whole systems. Because the estuaries are large lagoons, large volumes of fresh water are required to meet standards. However, this volume of water is not available during dry periods. We present a new concept, focused flows, for lower flow volumes that would maintain the ecological health of the upper reaches of estuaries during droughts. The concept is based on maintaining ecological integrity of nursery habitats, which is an important ecological function of estuaries. These focused flows would protect nursery habitats during droughts and allow estuaries to recover more quickly when the hydrology returns to average or higher flow periods. This approach could be applied globally where increasing water infrastructure and deficits are a concern or increasing aridity due to climate change is reducing river flows to coasts.

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Summary of Recommendations for the Future

Montagna,

Douglas

2025

Estuaries of the World

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While freshwater inflow (FWI) needs for the maintenance of estuary health have long been acknowledged, environmental flow standards or, specifically, FWI standards are still uncommon. Where they exist, they are rapidly evolving over time. Texas, USA, has been working on this problem since the 1960s. Through several iterations, the legal and regulatory framework evolved from a species management approach to an ecosystem-based management one. More recently, based on extensive scientific research, Texas adopted FWI standards for all the major bay systems between 2011 and 2014. After a decade however, new technical questions and problems have arisen. There are at least five major needs for the future: (1) While there is a lot of data, little of it is focused sufficiently to define estuary responses to inflow in a way that there are clear connections between physical characteristics and biological responses, so a state-wide monitoring approach is needed. (2) The physics-based models of circulation that are typically applied to Texas bays and estuaries are not up to the current scientific methods, so 3-D models are needed as well as updated bathymetry, shoreline locations, and salinity monitoring to calibrate and validate the models. (3) More mechanistic studies are needed that specifically link the biological response to physical dynamics, and this will be easier if the prior recommendations are enacted. (4) Because of the semi-arid climate, there will never be enough water to dilute salinity in all bay systems, especially in central and south Texas, so a focused approach to protect key nursery habitats during droughts is needed. (5) Finally, the FWI standards are complex, 3-D, hydrology tables that are difficult to apply, so a simpler approach is needed that specifically is linked to biological outcomes. This last recommendation may be impossible to implement if the first four are not implemented. While enormous progress has been made in Texas, there is still more to do, but the history of these activities can serve as a guide to any organization interested in the conservation, restoration, enhancement, or protection of estuaries anywhere in the world.

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Modeling the effect of water level on the Nueces Delta marsh community

Cited by 10 publications

References 26 publications

How a Simple Question About Freshwater Inflow to Estuaries Shaped a Career

How a Simple Question About Freshwater Inflow to Estuaries Shaped a Career

Focused Flows to Maintain Natural Nursery Habitats

Summary of Recommendations for the Future

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