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Hu Y, Zheng D, Shi S, Wang Y, Liu G, Song K, Mao D, Wu S, Tian L. Extraction of eutrophic and green ponds from segmentation of high-resolution imagery based on the EAF-Unet algorithm. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 343:123207. [PMID: 38154774 DOI: 10.1016/j.envpol.2023.123207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/25/2023] [Accepted: 12/20/2023] [Indexed: 12/30/2023]
Abstract
Inland ponds exhibit remarkable ubiquity across the globe, playing a vital role in the sustainability of global continental freshwater resources and contributing significantly to their biodiversity. Numerous ponds are eutrophic and experience recurrent seasonal or year-round algal blooms or persistent duckweed cover, conferring a characteristic green hue. Here, we denote these eutrophic and green ponds as EGPs. The excessive proliferation of algal blooms and duckweed within these EGPs poses a significant threat to the ecological functioning of these aquatic systems, which can lead to hypoxia or the release of microcystins. To identify these EGPs automatically, we constructed an Efficient Attention Fusion Unet (EAF-Unet) algorithm using Gaofen-2 (GF2) panchromatic and multispectral imagery. The attention mechanism was incorporated in Unet to help better detect EGPs. Using the first EGP labeled dataset, we determined the best input feature combination (RGB, NIR, NDVI, and Bright) and the most effective encoding (Rasnet50) for EAF-Unet for distinguishing EGPs from other ground cover types. The evaluation indices - Precision (0.81), Recall (0.79), F1-Score (0.80), and Intersection over Union (IoU, 0.67) - indicate that EAF-Unet can accurately and robustly extract EGPs from GF2 images without relying on pond water masks. Remote-sensing EGP products can assist in identifying ponds with severe eutrophication. Moreover, these products can serve as references for identifying high-risk areas prone to improper sewage discharge or inadequate sewer construction.
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Affiliation(s)
- Yating Hu
- College of Information Technology, Jilin Agricultural University, Changchun, 130118, China
| | - Danyang Zheng
- College of Information Technology, Jilin Agricultural University, Changchun, 130118, China
| | - Shuqiong Shi
- Ministry of Ecology and Environment of China, Beijing, 100029, China
| | - Yu Wang
- Center for Satellite Application on Ecology and Environment, Ministry of Ecology and Environment of the People's Republic of China, Beijing, 100029, China
| | - Ge Liu
- Northeast Institute of Geography and Agroecology, CAS, Changchun, 130102, China.
| | - Kaishan Song
- Northeast Institute of Geography and Agroecology, CAS, Changchun, 130102, China
| | - Dehua Mao
- Northeast Institute of Geography and Agroecology, CAS, Changchun, 130102, China
| | - Shihong Wu
- Tianjin Research Institute for Water Transport Engineering, State Ministry of Transport, Tianjin, 300456, China
| | - Liqiao Tian
- State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, 430079, China
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Terada K. Rainfall induced water and nutrient fluxes at a mangrove estuary. MARINE ENVIRONMENTAL RESEARCH 2022; 179:105674. [PMID: 35691261 DOI: 10.1016/j.marenvres.2022.105674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 05/06/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
Deep understanding of the nutrient exchange between a mangrove estuary and the surrounding coastal region is important for preserving nearshore biodiversity and sustaining appropriate human ecotourism. This study investigated the effect of tidal changes on the water quality and nutrient fluxes of a small mangrove estuary in Japan. Temporal changes in the water temperature, salinity, dissolved oxygen, turbidity, and nutrient concentrations (NO3, NH4, and TN) were measured. Nutrient fluxes were calculated using data collected from the Fukido Estuary in 2016 and compared against data collected in 2007. The results showed that NO3, NH4, and TN exhibited a negative correlation with salinity in 2016, but not in 2007. The water and TN net fluxes changed with rainfall. The findings of this study provide useful insights into the nutrient fluxes in a mangrove estuary and facilitate the evaluation of tidal fluctuations and weather-induced effects on nutrient fluxes.
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Affiliation(s)
- Kazumi Terada
- Department of Civil Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa, 259-1292, Japan.
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Carnevale C, Syme DA, Gamperl AK. Effects of hypoxic acclimation, muscle strain, and contraction frequency on nitric oxide-mediated myocardial performance in steelhead trout ( Oncorhynchus mykiss). Am J Physiol Regul Integr Comp Physiol 2021; 320:R588-R610. [PMID: 33501888 DOI: 10.1152/ajpregu.00014.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Whether hypoxic acclimation influences nitric oxide (NO)-mediated control of fish cardiac function is not known. Thus, we measured the function/performance of myocardial strips from normoxic- and hypoxic-acclimated (40% air saturation; ∼8 kPa O2) trout at several frequencies (20-80 contractions·min-1) and two muscle strain amplitudes (8% and 14%) when exposed to increasing concentrations of the NO donor sodium nitroprusside (SNP) (10-9 to 10-4 M). Further, we examined the influence of 1) nitric oxide synthase (NOS) produced NO [by blocking NOS with 10-4 M NG-monomethyl-l-arginine (l-NMMA)] and 2) soluble guanylyl cyclase mediated, NOS-independent, NO effects (i.e., after blockade with 10-4 M ODQ), on myocardial contractility. Hypoxic acclimation increased twitch duration by 8%-10% and decreased mass-specific net power by ∼35%. However, hypoxic acclimation only had minor impacts on the effects of SNP and the two blockers on myocardial function. The most surprising finding of the current study was the degree to which contraction frequency and strain amplitude influenced NO-mediated effects on myocardial power. For example, at 8% strain, 10-4 SNP resulted in a decrease in net power of ∼30% at 20 min-1 but an increase of ∼20% at 80 min-1, and this effect was magnified at 14% strain. This research suggests that hypoxic acclimation has only minor effects on NO-mediated myocardial contractility in salmonids, is the first to report the high frequency- and strain-dependent nature of NO effects on myocardial contractility in fishes, and supports previous work showing that NO effects on the heart (myocardium) are finely tuned spatiotemporally.
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Affiliation(s)
- Christian Carnevale
- Department of Ocean Sciences and Biology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Douglas A Syme
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - A Kurt Gamperl
- Department of Ocean Sciences and Biology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
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Resilience of Tropical Ecosystems to Ocean Deoxygenation. Trends Ecol Evol 2021; 36:227-238. [PMID: 33419595 DOI: 10.1016/j.tree.2020.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/03/2020] [Accepted: 11/10/2020] [Indexed: 01/18/2023]
Abstract
The impacts of ocean deoxygenation on biodiversity and ecosystem function are well established in temperate regions, and here we illustrate how the study of hypoxia in tropical ecosystems can offer insights of general importance. We first describe how mechanisms of resilience have developed in response to naturally occurring hypoxia across three tropical ecosystems: coral reefs, seagrass beds, and mangrove forests. We then suggest that the vulnerability of these systems to deoxygenation lies in interactions with other stressors that are increasing rapidly in the Anthropocene. Finally, we advocate for the adoption of a broader community- and ecosystem-level perspective that incorporates mutualisms, feedbacks, and mechanisms of self-rescue and recovery to develop a better predictive understanding of the effects of deoxygenation in coastal ecosystems.
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Walden G, Noirot C, Nagelkerken I. A future 1.2 °C increase in ocean temperature alters the quality of mangrove habitats for marine plants and animals. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 690:596-603. [PMID: 31301500 DOI: 10.1016/j.scitotenv.2019.07.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/01/2019] [Accepted: 07/03/2019] [Indexed: 06/10/2023]
Abstract
Global climate stressors, like ocean warming and acidification, contribute to the erosion of structural complexity in marine foundation habitats by promoting the growth of low-relief turf, increasing grazing pressure on structurally complex marine vegetation, and by directly affecting the growth and survival of foundation species. Because mangrove roots are woody and their epibionts are used to ever-changing conditions in highly variable environments, mangrove habitats may be more resilient to global change stressors than other marine foundation species. Using a large-scale mesocosm experiment, we examined how ocean warming and acidification, under a reduced carbon emission scenario, affect the composition and structural complexity of mangrove epibiont communities and the use of mangrove habitat by juvenile fishes. We demonstrate that even a modest increase in seawater temperature of 1.2 °C leads to the homogenisation and flattening of mangrove root epibiont communities. Warming led to a 24% increase in the overall cover of algal epibionts on roots but the diversity of the epibiont species decreased by 33%. Epibiont structural complexity decreased owing to the shorter stature of weedy algal turfs which prospered under elevated temperature. Juvenile fishes showed alterations in mangrove habitat use with ocean warming and acidification, but these were independent of changes to the root epibiont community. We reveal that the quality of apparently resilient mangrove habitats and their perceived value as habitat for associated fauna are still vulnerable under a globally reduced carbon emission scenario.
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Affiliation(s)
- Georgia Walden
- Southern Seas Ecology Laboratories, School of Biological Sciences and The Environment Institute, DX650 418, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Christelle Noirot
- Southern Seas Ecology Laboratories, School of Biological Sciences and The Environment Institute, DX650 418, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Ivan Nagelkerken
- Southern Seas Ecology Laboratories, School of Biological Sciences and The Environment Institute, DX650 418, The University of Adelaide, Adelaide, SA 5005, Australia.
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Chuard PJC, Johnson MD, Guichard F. Ocean acidification causes mortality in the medusa stage of the cubozoan Carybdea xaymacana. Sci Rep 2019; 9:5622. [PMID: 30948764 PMCID: PMC6449339 DOI: 10.1038/s41598-019-42121-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/25/2019] [Indexed: 11/28/2022] Open
Abstract
Ocean pH is decreasing due to anthropogenic activities, and the consequences of this acidification on marine fauna and ecosystems are the subject of an increasing number of studies. Yet, the impact of ocean acidification (OA) on several abundant and ecologically important taxa, such as medusozoans, is poorly documented. To date there have been no studies on the effect of post-2050 OA projections on the medusa stage of jellyfish. As medusae represent the reproductive stage of cnidarians, negative impacts on adult jellyfish could severely impact the long-term survival of this group. Using a laboratory experiment, we investigated the effect of 2300 OA projections (i.e. pH of 7.5) on the mortality rate of the medusa-stage of the cubozoan species Carybdea xaymacana, compared to ambient seawater pH conditions (i.e. pH of 8.1). After a 12-h exposure to OA, C. xaymacana medusae suffered higher mortality rates compared to ambient conditions. This study represents the first evidence of the potential lethal effects of post-2050 OA projections on jellyfish. The higher metabolic rates of cubozoans compared to other cnidarians might make box jellyfish more vulnerable to OA. A decrease in the density of cnidarians could lead to harmful ecological events, such as algal blooms.
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Affiliation(s)
- Pierre J C Chuard
- Department of Biological Sciences, Bishop's University, Sherbrooke, QC, J1M 1Z7, Canada.
| | | | - Frédéric Guichard
- Department of Biology, McGill University, Montreal, QC, H3A 1B1, Canada
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