Changes in sediment regimes and mass accumulation rates in Eeyou Istchee eelgrass habitat, James Bay, Canada

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology Pub Date : 2025-02-20 DOI:10.1016/j.margeo.2025.107514

Madelyn A. Stocking , Sophia C. Johannessen , Zou Zou A. Kuzyk

{"title":"Changes in sediment regimes and mass accumulation rates in Eeyou Istchee eelgrass habitat, James Bay, Canada","authors":"Madelyn A. Stocking , Sophia C. Johannessen , Zou Zou A. Kuzyk","doi":"10.1016/j.margeo.2025.107514","DOIUrl":null,"url":null,"abstract":"<div><div>Fourteen sediment cores collected from shallow subtidal waters in 2017–2021 in northeastern James Bay, Canada (known as Eeyou Istchee) were analyzed for excess 210Pb (210Pbex), 137Cs and fine particle content (% <63 μm) to characterize sediment deposition within an eelgrass (Zostera marina) ecosystem recovering from a massive decline in the 1990s. A strong signature of surface soil input from nearby La Grande Rivière watershed is evident from high 137Cs inventories and low 210Pbex/137Cs ratios. Mass accumulation rates (MARs) were established in five cores using a 210Pbex model that accounts for bio-mixing and subsequently validated by 137Cs. MARs are higher in this area (0.14–0.48 g cm−2 yr−1) than in nearby offshore Hudson Bay. Low inventories of 210Pbex and 137Cs and disturbances in particle size distribution (coarsening upwards) in the remaining cores indicate non-steady-state behaviour, most likely surficial erosion. Using well-preserved 137Cs peaks and other core-specific methods, pre-disturbance MARs were estimated at between <0.05 and 0.39 g cm−2 yr−1, indicating an environmental transition from net accumulation to erosion. Recent deposition of sediment is largely controlled by sediment focusing, resulting in high variability of inventories and MARs at small spatial scales. The loss of eelgrass has likely increased sediment resuspension and redistribution to deeper areas, contributing to decreased light availability for subtidal eelgrass and increased export of material to greater James Bay. The findings of this study show the foundational importance of small-scale assessment of MARs in river-dominated eelgrass ecosystems like those in Eeyou Istchee.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"483 ","pages":"Article 107514"},"PeriodicalIF":2.6000,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Marine Geology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0025322725000398","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 0

Abstract

Fourteen sediment cores collected from shallow subtidal waters in 2017–2021 in northeastern James Bay, Canada (known as Eeyou Istchee) were analyzed for excess ²¹⁰Pb (²¹⁰Pb_ex), ¹³⁷Cs and fine particle content (% <63 μm) to characterize sediment deposition within an eelgrass (Zostera marina) ecosystem recovering from a massive decline in the 1990s. A strong signature of surface soil input from nearby La Grande Rivière watershed is evident from high ¹³⁷Cs inventories and low ²¹⁰Pb_ex/¹³⁷Cs ratios. Mass accumulation rates (MARs) were established in five cores using a ²¹⁰Pb_ex model that accounts for bio-mixing and subsequently validated by ¹³⁷Cs. MARs are higher in this area (0.14–0.48 g cm⁻² yr⁻¹) than in nearby offshore Hudson Bay. Low inventories of ²¹⁰Pb_ex and ¹³⁷Cs and disturbances in particle size distribution (coarsening upwards) in the remaining cores indicate non-steady-state behaviour, most likely surficial erosion. Using well-preserved ¹³⁷Cs peaks and other core-specific methods, pre-disturbance MARs were estimated at between <0.05 and 0.39 g cm⁻² yr⁻¹, indicating an environmental transition from net accumulation to erosion. Recent deposition of sediment is largely controlled by sediment focusing, resulting in high variability of inventories and MARs at small spatial scales. The loss of eelgrass has likely increased sediment resuspension and redistribution to deeper areas, contributing to decreased light availability for subtidal eelgrass and increased export of material to greater James Bay. The findings of this study show the foundational importance of small-scale assessment of MARs in river-dominated eelgrass ecosystems like those in Eeyou Istchee.

查看原文本刊更多论文

求助全文

约1分钟内获得全文求助全文

来源期刊

Marine Geology 地学-地球科学综合

CiteScore

6.10

自引率

6.90%

发文量

175

审稿时长

21.9 weeks

期刊介绍： Marine Geology is the premier international journal on marine geological processes in the broadest sense. We seek papers that are comprehensive, interdisciplinary and synthetic that will be lasting contributions to the field. Although most papers are based on regional studies, they must demonstrate new findings of international significance. We accept papers on subjects as diverse as seafloor hydrothermal systems, beach dynamics, early diagenesis, microbiological studies in sediments, palaeoclimate studies and geophysical studies of the seabed. We encourage papers that address emerging new fields, for example the influence of anthropogenic processes on coastal/marine geology and coastal/marine geoarchaeology. We insist that the papers are concerned with the marine realm and that they deal with geology: with rocks, sediments, and physical and chemical processes affecting them. Papers should address scientific hypotheses: highly descriptive data compilations or papers that deal only with marine management and risk assessment should be submitted to other journals. Papers on laboratory or modelling studies must demonstrate direct relevance to marine processes or deposits. The primary criteria for acceptance of papers is that the science is of high quality, novel, significant, and of broad international interest.