Abstract Mangroves and saltmarshes are biogeochemical hotspots storing carbon in sediments and in the ocean following lateral carbon export (outwelling). Coastal seawater pH is modified by both uptake of anthropogenic carbon dioxide and natural biogeochemical processes, e.g., wetland inputs. Here, we investigate how mangroves and saltmarshes influence coastal carbonate chemistry and quantify the contribution of alkalinity and dissolved inorganic carbon (DIC) outwelling to blue carbon budgets. Observations from 45 mangroves and 16 saltmarshes worldwide revealed that &gt;70% of intertidal wetlands export more DIC than alkalinity, potentially decreasing the pH of coastal waters. Porewater-derived DIC outwelling (81 ± 47 mmol m −2 d −1 in mangroves and 57 ± 104 mmol m −2 d −1 in saltmarshes) was the major term in blue carbon budgets. However, substantial amounts of fixed carbon remain unaccounted for. Concurrently, alkalinity outwelling was similar or higher than sediment carbon burial and is therefore a significant but often overlooked carbon sequestration mechanism. 

Carbonate chemistry and carbon sequestration driven by inorganic carbon outwelling from mangroves and saltmarshes

Air-water CO2 fluxes in estuarine environments are characterized by high interannual variability, in part due to hydrological variability that alters estuarine carbonate chemistry through multiple physical and biogeochemical processes. To understand the relative contributions of these varied controls on interannual air-water CO2 fluxes in the mainstem Chesapeake Bay, we implemented both hindcast and scenario simulations using a coupled physical-biogeochemical model. Significant spatiotemporal variability in bay-wide fluxes was found over a 10-year period (1996-2005), where the mainstem Bay was primarily a net CO2 sink, except in drought periods. Sensitivity scenario results suggested substantial effects of riverine nutrient and organic matter (OM) inputs to CO2 flux variations. The high correlations between riverine inputs and upper-Bay fluxes were due to elevated respiration under increased OM inputs. The interannual flux variations in the lower Bay was mostly regulated by the nutrient inputs. Both nutrient and OM inputs contributed to the flux variability in the mid Bay. It is found that the interannual CO2 flux of the mainstem was most sensitive to riverine nutrient inputs associated with the hydrological changes. For each hindcast simulation we computed the ratio of organic carbon turnover time to water residence time (λ), a proxy for CO2 efflux potential, and found that the wetter periods had a relatively lower λ. The variability of mainstem CO2 fluxes can be well represented using a generic function of λ. The model results showed that higher river flows would lead to enhanced CO2 sinks into a large eutrophic estuary by promoting net autotrophy. 

Interannual variability of air-water CO2 flux in a large eutrophic estuary.

Climate-induced changes in hypoxia are among the most serious threats facing estuaries, which are among the most productive ecosystems on Earth. Future projections of estuarine hypoxia typically involve long-term multi-decadal continuous simulations or more computationally efficient time slice and delta methods that are restricted to short historical and future periods. We make a first comparison of these three methods by applying a linked terrestrial–estuarine model to the Chesapeake Bay, a large coastal-plain estuary in the eastern United States. Results show that the time slice approach accurately captures the behavior of the continuous approach, indicating a minimal impact of model memory. However, increases in mean annual hypoxic volume by the mid-twenty-first century simulated by the delta approach (+ 19%) are approximately twice as large as the time slice and continuous experiments (+ 9% and + 11%, respectively), indicating an important impact of changes in climate variability. Our findings suggest that system memory and projected changes in climate variability, as well as simulation length and natural variability of system hypoxia, should be considered when deciding to apply the more computationally efficient delta and time slice methods. 

pdf/response-of-hypoxia-to-future-climate-change-is-sensitive-to-6pnmogmi9u4c.pdf

Response of hypoxia to future climate change is sensitive to methodological assumptions

Warming and nutrient pollution are among the factors contributing to complex changes in aquatic systems. Two of the common impacts in estuaries and coastal systems are hypoxia and harmful algal blooms. This chapter begins with operational definitions of these phenomena and the harm caused by such events, then explores how hypoxia and algal blooms are changing globally, the mechanisms by which hypoxia and HABs may form, and, using models and examples from the largest estuary in the U.S., the Chesapeake Bay, the complexities of future changes are demonstrated. The trajectories of future changes are not promising for ecosystem recovery. 

Warming, Wheezing, Blooming Waters: Hypoxia and Harmful Algal Blooms

One of the central challenges for the coastal and marine science community is to project how the biological and physical conditions of the world's oceans and estuaries will be altered by climate change. Numerical simulation models play important roles in assessing the potential effects of climate change on coastal ecosystems and developing management strategies aimed at minimizing risks to sensitive habitats, species and people living along the coasts. Numerical models also provide a quantitative framework to disentangle the synergistic influences of multiple factors and isolate the effects of individual stressors. Here, we provide a brief overview of numerical simulation models used to assess the potential effects of climate change on coastal ecosystems. We then highlight three selected case studies where models have been used to project climate change impacts in two large coastal ecosystems, the northern Gulf of Mexico and Chesapeake Bay. Finally, we conclude with a discussion of challenges for the use of models to address climate change, highlighting the need for observations, models that better represent the complex and flexible biological communities in the marine environment, and a need to better represent feedbacks in ecosystem models. 

Coastal Ecosystem Modeling in the Context of Climate Change

Impact of estuarine reclamation projects on saltwater intrusion and freshwater resource

Disentangling the Effects of Global and Regional Drivers on Diverse Long‐Term pH Trends in Coastal Waters

Abstract Most estuaries are substantial sources of carbon dioxide (CO 2 ) to the atmosphere. The estimated estuarine CO 2 degassing is about 17% of the total oceanic uptake, but the effect of rising atmospheric CO 2 on estuarine carbon balance remains unclear. Here we use 3D hydrodynamic-biogeochemical models of a large eutrophic estuary and a box model of two generic, but contrasting estuaries to generalize how climate change affects estuarine carbonate chemistry and CO 2 fluxes. We found that small estuaries with short flushing times remain a CO 2 source to the atmosphere, but large estuaries with long flushing times may become a greater carbon sink and acidify. In particular, climate downscaling projections for Chesapeake Bay in the mid-21st century showed a near-doubling of CO 2 uptake, a pH decline of 0.1–0.3, and &gt;90% expansion of the acidic volume. Our findings suggest that large eutrophic estuaries will become carbon sinks and suffer from accelerated acidification in a changing climate. 

/pdf/projected-increase-in-carbon-dioxide-drawdown-and-1soia90o.pdf

Projected increase in carbon dioxide drawdown and acidification in large estuaries under climate change

Impact of Hurricane Ian (2022) on Karenia brevis Bloom on the West Florida Shelf

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Ming Li

Author Tools

Chat about Author