Tidal Changes Research Articles

Advancing the Interpretation of Shallow Water Marine Soundscapes

Soundscapes offer rich descriptions of composite acoustic environments. Characterizing marine soundscapes simply through sound levels results in incomplete descriptions, limits the understanding of unique features, and impedes meaningful comparisons. Sources that contribute to sound level metrics shift in time and space with changes in biological patterns, physical forces, and human activity. The presence of a constant or chronic source is often interwoven with episodic sounds. Further, the presence and intensity of sources can influence other sources, calling for a more integrated approach to characterizing soundscapes. Here, we illustrate this complexity using data from a national-scale effort, the Sanctuary Soundscape Monitoring Project (SanctSound), an initiative designed to support collection of biological, environmental, and human use data to compliment the interpretation of sound level measurements. Using nine examples from this diverse dataset we demonstrate the benefit of integrating source identification and site features to interpret sound levels across a diversity of shallow water marine soundscapes (<150 m). Sound levels from sites in high human use areas reflect the anthropogenic influences on the soundscape, especially when measuring broad frequency bands, whereas sites with relatively low human activity and high sound levels reveal biological features of the soundscape. At sites with large tidal changes, sound levels correlated with the magnitude of tidal flow, and sound levels during high tidal flow periods were similar to sound levels at sites near commercial shipping lanes. At sites in relatively close proximity (<30 km), sound levels diverge because of the presence of different proximate sound contributors and propagation features of the site. A review of emerging methodologies for integrated soundscape analysis, including acoustic scenes, provides a framework for interpreting soundscapes across a variety of conditions. With a global growth in monitoring efforts collecting standardized measurements over widely distributed arrays, more integrated methods are needed to advance the utility of soundscapes in marine resource management.

Targeted delivery of pentagalloyl glucose inhibits matrix metalloproteinase activity and preserves elastin in emphysematous lungs

BackgroundElastin degradation has been established as one of the driving factors of emphysema. Elastin-derived peptides (EDPs) are shown to act as a chemoattractant for monocytes. Effectively shielding elastin from elastolytic damage and regenerating lost elastin are two important steps in improving the mechanical function of damaged lungs. Pentagalloyl glucose (PGG) has been shown to preserve elastin in vascular tissues from elastolytic damage in vivo and aid in elastin deposition in vitro.MethodsWe created emphysema by elastase inhalation challenge in mice. Albumin nanoparticles loaded with PGG, conjugated with elastin antibody, were delivered to target degraded elastin in lungs. We investigated matrix metalloproteinase-12 activity and lung damage by measuring dynamic compliance and tidal volume changes.ResultsEx-vivo experiments demonstrated elastin preservation in PGG treated samples compared to controls. Inhaled nanoparticles conjugated with elastin antibody retained for extended periods in lungs. Further, mice treated with PGG nanoparticles showed a significant suppression of MMP-12 activity measured in the lungs. We observed suppression of emphysema in terms of dynamic lung compliance and tidal volume change compared to the control group. The histological examination further confirmed elastin preservation in the lungs.ConclusionThese results demonstrate successful targeted delivery of nanoparticles loaded with PGG to inhibit MMP-12 activity and preserve elastin in the lungs. Such targeted PGG therapy has potential therapeutic use in the management of emphysema.

Circadian and circatidal rhythms of protein abundance in the California mussel (Mytilus californianus).

Coastal habitats fluctuate with the 12.4h tidal and 24h light/dark cycle to predictably alter conditions such as air exposure, temperature, and food availability. Intertidal sessile bivalves exhibit behavioural and physiological adjustments to minimize the challenges of this environment. We investigated a high-resolution time course of the changes in protein abundance in the gill tissue of the intertidal mussel Mytilus californianus in a simulated tidal environment of 12:12h light:dark cycles and a matching 6:6h high:low tide cycle within each 12h period. Approximately 38% of detected proteins showed significant rhythms in their abundances, with diversity in the phases of rhythmic isoforms. The circadian rhythm was dominant in protein abundance changes, particularly with oxidative metabolism. A tidal cycle elicited changes within functional groups, including in cytoskeletal proteins, chaperones, and oxidative stress proteins. In addition to protein abundance changes, we found the possibility for post-translational modifications driving rhythms, including methylation, mitochondrial peptide processing (proteolysis), and acylation. Dynamic changes in the proteome across functional categories demonstrate the importance of the tidal environment in entraining cellular processes, confirming that differential expression studies should not assume a static baseline of cellular conditions in intertidal organisms.

Dynamic relative regional strain visualized by electrical impedance tomography in patients suffering from COVID-19

Respiratory failure due to SARS-CoV-2 may progress rapidly. During the course of COVID-19, patients develop an increased respiratory drive, which may induce high mechanical strain a known risk factor for Patient Self-Inflicted Lung Injury (P-SILI). We developed a novel Electrical Impedance Tomography-based approach to visualize the Dynamic Relative Regional Strain (DRRS) in SARS-CoV-2 positive patients and compared these findings with measurements in lung healthy volunteers. DRRS was defined as the ratio of tidal impedance changes and end-expiratory lung impedance within each pixel of the lung region. DRRS values of the ten patients were considerably higher than those of the ten healthy volunteers. On repeated examination, patterns, magnitude and frequency distribution of DRRS were reproducible and in line with the clinical course of the patients. Lung ultrasound scores correlated with the number of pixels showing DRRS values above the derived threshold. Using Electrical Impedance Tomography we were able to generate, for the first time, images of DRRS which might indicate P-SILI in patients suffering from COVID-19.Trial Registration This observational study was registered 06.04.2020 in German Clinical Trials Register (DRKS00021276).

Life Cycle of Edible Jellyfish Acromitus hardenbergi Stiasny, 1934 (Scyphozoa: Rhizostomeae) Inhabiting a Brackish-Water Environment.

Simple SummaryThe edible jellyfish Acromitus hardenbergi Stiasny, 1934 is an important fishery resource. The aim of the present study was to elucidate the life history of this brackish-water jellyfish in order to conserve the species and develop sustainable jellyfish fisheries. Matured medusae were collected at the mouth of the Perak River. Primary polyps had a long stalk with a small stolon at the base of the calyx. Fully developed polyps were bowl- or goblet-shaped. Asexual reproduction was accomplished only by means of budding. Strobilation was mono-disc type. Polyps of A. hardenbergi expand their population not by podocysts, but by budding as quickly as possible and forming one large ephyra by mono-disc strobilation without the residuum, because the polyp cannot remain for a long time at its settlement place where there is a sediment-rich environment with drastic salinity change.The edible jellyfish Acromitus hardenbergi Stiasny, 1934 is harvested throughout the year at the mouth of the Perak River, Malaysia. Although this species is an important fishery resource in the local area, limited biological studies have been carried out on it. The aim of the present study was to elucidate the life cycle of this unique brackish-water jellyfish in order to conserve the species and develop sustainable jellyfish fisheries. Mature medusae were collected at the mouth of the Perak River. Embryonic and larval development after fertilization was completed within 24 h until the planula stage and within 48 h until the polyp stage. Primary polyps had a long stalk with a small stolon at the base of the calyx. Fully developed polyps were bowl-or goblet-shaped but became an elongated stalk under starved conditions. Asexual reproduction was accomplished only by means of budding, and no podocysts were produced. Strobilation was mono-disc type. These characteristics may be adaptations to the dynamic environmental conditions in the estuary of the Perak River, where salinity fluctuates widely due to strong inflows of highly turbid freshwater coupled with tidal changes. This study suggests that polyps of A. hardenbergi expand their population not by podocysts, but by budding as quickly as possible and forming one large ephyra by mono-disc strobilation without the residuum, because the polyp cannot remain for a long time at its settlement place in the sediment-rich environment with drastic salinity change.

Temporal variation in radiocarbon pathways caused by sea-level and tidal changes in the Bonaparte Gulf, northwestern Australia

Radiocarbon dating, applied to carbon-containing material such as shells, foraminifers, corals, peats, and bulk organic matter, is an essential method for constraining Late Quaternary age models. However, selection of appropriate material requires paleoenvironmental knowledge because past climate and sea-level variability may affect depositional processes. To illustrate this issue, we present radiocarbon dates performed on marine and terrestrial macrofossils, foraminifers, and acid-insoluble carbon (AIC), as well as paleo-tidal modeling results, from the Bonaparte Gulf in northwestern Australia. The varied topography and large tidal range of the Bonaparte Gulf strongly influence the past sedimentary environment in response to sea-level change. At sea level −70 m below present, carbonate fossil material is a more reliable indicator of the depositional age than AIC, with little lateral transport because of isolation from the open ocean and reduced tidal activity. In contrast, high tidal activity occurs when sea level is above −70 m, with significant redeposition of older fossil material. In this case the AIC dates are more reliable. This is the opposite relationship typically observed in less dynamic settings because the varied and uncertain AIC pathways. This result underscores the need to understand the past depositional environment, particularly on the continental shelves, which are highly affected by sea-level changes.

Noninvasive Tidal Volume Measurements, Using a Time-of-Flight Camera, Under High-Flow Nasal Cannula-A Physiological Evaluation, in Healthy Volunteers.

The mechanisms of high-flow nasal cannula are still debated but may be mediated by the generation of low positive end-expiratory pressure and a washout of the airway dead space. The aims of this study were to assess the effects of high-flow nasal cannula on tidal volume using a noninvasive method using a time-of-flight camera, under various conditions. A physiologic evaluation in healthy volunteers. An university hospital ICU. Ten healthy volunteers were included in a physiologic study (CamOpt study, ClinicalTrials.gov identifier: NCT04096183). All volunteers were submitted to 12 different conditions (i.e., gas flow [baseline = 0; 30-60 L/min]; mouth [open/closed]; respiratory rate [baseline; baseline + 10 breaths/min]). Tidal volume measurements were performed every minute, during a 6-minute recording period. In all combinations, reference respiratory rate was measured by using chronometric evaluation, over a 30-second period (RRREF), and by using the time-of-flight camera (RRTOF). Tidal volume increased while increasing gas flow whatever the respiratory rate and mouth condition (p < 0.001). Similar results were observed whatever the experimental conditions (p < 0.01), except one (baseline respiratory rate + 10 breaths/min and mouth closed). Tidal volume increased while decreasing respiratory rate (p < 0.001) and mouth closing (p < 0.05). Proportion of tidal volume greater than 10, 15, and 20 mL/kg changed while increasing the flow. RRTOF was in agreement with RRREF (intraclass correlation coefficient, 0.96), with a low mean bias (0.55 breaths/min) and acceptable deviation. Time-of-flight enables to detect tidal volume changes under various conditions of high-flow nasal cannula application. Tidal volume increased significantly while increasing gas flow and mouth closing. Such technique might be useful to monitor the risk of patient self-inflicted lung injury or under assistance.

Search Behavior Regarding Cancer Susceptibility Genes Using a Clinical Decision Support Tool for Gene-Specific Penetrance: Content Analysis.

BackgroundGenetic testing for germline cancer susceptibility genes is widely available. The Ask2Me.org (All Syndromes Known to Man Evaluator) tool is a clinical decision support tool that provides evidence-based risk predictions for individuals with pathogenic variants in cancer susceptibility genes.ObjectiveThe aim of this study was to understand the search behavior of the Ask2Me.org tool users, identify the patterns of queries entered, and discuss how to further improve the tool.MethodsWe analyzed the Ask2Me.org user-generated queries collected between December 12, 2018, and October 8, 2019. The gene frequencies of the user-generated queries were compared with previously published panel testing data to assess the correspondence between usage and prevalence of pathogenic variants. The frequencies of prior cancer in the user-generated queries were compared with the most recent US population–based cancer incidence.ResultsA total of 10,085 search queries were evaluated. The average age submitted in the queries was 48.8 (SD 16.5) years, and 84.1% (8478/10,085) of the submitted queries were for females. BRCA2 (1671/10,085, 16.6%), BRCA1 (1627/10,085, 16.1%), CHEK2 (994/10,085, 9.9%), ATM (662/10,085, 6.6%), and APC (492/10,085, 4.9%) were the top 5 genes searched by users. There was a strong linear correlation between genes queried by users and the frequency of pathogenic variants reported in published panel testing data (r=0.95, r2=0.90, P<.001). Over half of the queries (5343/10,085, 53.0%) included a prior personal history of cancer. The frequencies of prior cancers in the queries on females were strongly correlated with US cancer incidences (r=0.97, r2=0.95, P<.001), while the same correlation was weaker among the queries on males (r=0.69, r2=0.47, P=.02).ConclusionsThe patients entered in the Ask2Me.org tool are a representative cohort of patients with pathogenic variants in cancer susceptibility genes in the United States. While a majority of the queries were on breast cancer susceptibility genes, users also queried susceptibility genes with lower prevalence, which may represent a transformation from single gene testing to multigene panel testing. Owing to these changing tides, more efforts are needed to improve evidence-based clinical decision support tools to better aid clinicians and their practice.

Tidal forces in Kottler spacetimes

The article considers tidal forces in the vicinity of the Kottler black hole. We find a solution of the geodesic deviation equation for radially falling bodies, which is determined by elliptic integrals. And also the asymptotic behavior of all spatial geodesic deviation vector components were found. We demonstrate that the radial component of the tidal force changes sign outside the single event horizon for any negative values of the cosmological constant, in contrast to the Schwarzschild black hole, where all the components of the tidal force are sign-constant. We also find the similarity between the Kottler black hole and the Reissner–Nordström black hole, because we indicate the value of the cosmological constant, which ensures the existence of two horizons of the black hole, between which the angular components of the tidal force change sign. It was possible to detect non-analytical behavior of geodesic deviation vector components in anti-de Sitter spacetime and to describe it locally.

Extubation generates lung volume inhomogeneity in preterm infants

ObjectiveTo evaluate the feasibility of electrical impedance tomography (EIT) to describe the regional tidal ventilation (VT) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process...

Assessing salinization of coastal groundwater by tidal action: The tropical Wouri Estuary, Douala, Cameroon

Study regionDouala, Cameroon, West Africa. Study focusSalinity of shallow coastal groundwater in Douala, Cameroon impairs its use for drinking and industrial purposes. Previous studies suggest that salinization is from tidal flooding from the Wouri Estuary. We aimed to test the tidal origin of groundwater salinization by conducting a time series investigation of water level and salinity, and assessed the stable water isotopes (δ¹⁸O and δD) and major cations (Ca²+ and Mg²+) in groundwater and adjacent estuarine tidal creek. During the time series measurements, we pumped groundwater for over 5 tidal cycles to induce flow into a test well. New hydrologic insights for the regionThe time-series groundwater level mimicked water level changes in the estuary. However, the temporal salinity in groundwater did not correspond to tidal salinity changes of estuarine water, indicating that estuarine water did not intrude groundwater. The δ¹⁸O and δD of the groundwater and estuarine samples are collinear and fall along the local meteoric water line of Douala and had d-excesses of >10, indicating a non-evaporated rain recharge of groundwater or lack of salinization by evapoconcentration. The salinity-δ¹⁸O relationship showed that the origin of salinity in the coastal groundwater aquifer is not from seawater intrusion. The Mg²+/Ca²+ ratios of <1 in groundwater compared to 6–8 in estuarine water support the non-seawater origin of groundwater salinity. We conclude that the salinity of coastal groundwater in Douala is not affected by tide-induced salinization from the adjacent Wouri Estuary but by geogenic sources in the aquifer.

Sustaining Esturial Creeks: Water Corridors in Mitigating Flooding in Manila, Philippines

This paper articulates that estuarial creeks as water corridors are essential part of urban flooding mitigation. These water corridors drain excess water from the city to the bay area reducing inland flooding while at the same time flushing pollutants during tidal changes. Using an institutional analysis, it is argued that estuarial creek rehabilitation in the City of Manila, Philippines is based on mandate, policies, legal frame, and programs. Results show that the estuarial creeks have been silent witnesses to the changing human landscape of Manila. These water corridors in congested Manila have been cleared, cleaned and widened by government agencies but were not maintained as natural space breaks in mitigating flood due to short term targets. Their deteriorating conditions have added to Manila’s waterway misery. In conclusion, the rehabilitation of the esteros is a reflection of the institutional arrangements in managing the waterway system in Metro Manila.

Evolution of an estuarine valley to barrier-lagoon system promoted by tidal prism change during a transgressive event (Lower Permian, Paraná Basin)

In modern marine marginal environments, the coastal morphology directly influences the tidal and wave processes. In this paper we present an example of an ancient coastal zone where the change in coastal morphology controlled the tidal range. This study focuses on the Permian Rio Bonito Formation in the southern Paraná Basin, where the major coal deposits of South America are located. Sedimentological and stratigraphical approaches were applied to cores drilled in the Candiota paleovalley area. We describe the stratigraphic architecture of a transgressive event of the Lower Permian (Rio Bonito Formation). Two third order depositional sequences were identified, which show differences in the paleoenvironmental record. In the lower sequence, associated with the infilling of an incised valley, facies related to fluvial and tidal currents are dominant. In a micro-tidal inner sea context, tidal range is amplified in a funnel-shaped valley. In the upper sequence, already evolving in linear coastal conditions, evidence of tidal depositional processes almost disappear, and the sedimentation becomes dominated by wave processes, thus a coastal barrier system associated with lagoons and swamps is established. Our study, besides detailing the paleoenvironmental evolution of the sedimentary infilling of an incised valley, also provides for a better understanding of the origin of southern Brazil coal.

Revisiting Plural Marriage in the 21st Century: Polygamy, Politics and Power

This paper reviews the complex history of plural marriage associated with the Mormon Church, giving consideration to views that are both favorable and unfavorable to the practice of polygamy. Interdisciplinary in nature, this paper delves into the religious underpinnings common to the practice of polygamy in the United States, alongside a discussion of media framing and court decisions that could impact the future of polygamy. Utilizing a social constructionist framework informed by historical information, media narratives from women who have experienced polygamy first-hand, and legal arguments surrounding the practice of plural marriage, the author argues that modern opposition to polygamy is rooted in ideas of moral superiority and is not aligned with many historical accounts of polygamy nor with the changing tides of legal recognition of fundamental rights and familial status occurring in the United States in the 21st century.

RETRACTED ARTICLE: Design and simulation analysis of offshore tidal energy generating set system based on sensor network

Tidal energy refers to the potential energy and kinetic energy of tidal changes. It is a kind of energy that hides a huge amount of energy and can be regenerated endlessly. Tidal energy as an energy source is purely renewable energy. The tide rises and falls every day, and the energy is constant, so it will be endless. Power generation through tidal energy cannot only alleviate the energy shortage but also become the main additional energy source for people to carry out economic construction and development in areas near the sea. Because tidal power plants are usually built-in offshore areas with relatively small populations, they will not cause complicated problems such as flooding of farmland and immigration. In view of the shortage of energy and fuel in the world and the increasingly serious environmental and pollution problems, tidal energy has received widespread attention and influence all over the world due to its infinite reserves, lack of environmental pollution, and high predictability. Based on the submarine acoustic wireless sensor network platform, we have developed an experimental submarine acoustic ray sensor network platform, which provides an effective platform for testing and evaluating the submarine acoustic ray sensor network. This paper determines the capacity of TCF, the layout design of TCF in TCT, and the research on the collection system. Based on the underwater acoustic wireless sensor network platform, the underwater acoustic network experimental test system platform is being developed, and a feasible research plan is proposed for the detection and evaluation of the underwater acoustic wireless sensor network.

Multiple Driver Impacts on Rocky Intertidal Systems: The Need for an Integrated Approach

Most intertidal rocky systems are exposed to severe tidal, diurnal, and seasonal changes in environmental parameters. In addition, they show extreme vulnerability to anthropogenic impacts. Research on multiple drivers is therefore crucial to understand the complexity of their potential interactions. Here, we first give an overview of the natural environment and impacts of climate change on rocky shore intertidal systems, and then focus on the impacts of multiple drivers. We further provide a summary of existing multiple driver studies in the literature with the aim for a better understanding of multiple driver interactions. As multiple drivers can affect rocky shore intertidal systems at different spatial and temporal scales, and the outcome of their effects are still more of an “ecological surprise,” we recommend a more widespread assessment of the environmental and biological context. We propose a new, integrated approach based on existing literature: this complements previous frameworks but with an improved understanding of co-occurring multiple driver systems of the rocky intertidal, in order to find management solutions based on accurate and informed predictions in these times of global change.

Study on Flood Simulation of Tallo Watershed, Makassar City, South Sulawesi Province

Tallo watershed has a length of 70 km, its area width is 407.00 ¬¬km2, the river upstream or downstream is at an altitude of ± 1,100 m above sea level located on Mount Kaliapolompo in which the overall length of the river in Tallo watershed totaling ± 131.50 km2. The research objective was to analyze the effect of five-year flood discharge and tidal changes on the inundation area and flood depth in Tallo watershed. The method of rainfall analysis used the Log Pearson type III method where the flow is considered to be two horizontal dimensions with even velocity at each depth. A five-year period with a discharge value of 127.64 m3/s will statistically reoccur every five years with an estimated chance of occurrence of 0.2 or 20% for each year referred to in a 5-year review cycle. The results of the simulation were then known that the five-year flood discharge resulted in flooding with a depth of 0-3 meters from the maximum tide condition (HWSL), and an inundation area of 31.91 km2 inundated the Tallo District, Tamalanrea District, Panakukang District, West Biringkanaya District and northern Manggala District. These areas are located on the left and right of the Tallo River with an altitude between 0 and 2 meters above sea level.

The Influence of Channel Deepening on Tides, River Discharge Effects, and Storm Surge

AbstractWe combine archival research, semi‐analytical models, and numerical simulations to address the following question: how do changes to channel geometry alter tidal properties and flood dynamics in a hyposynchronous, strongly frictional estuary with a landward decay in tidal amplitudes? Records in the Saint Johns River Estuary since the 1890s show that tidal range has doubled in Jacksonville, Florida. Near the estuary inlet, tidal discharge approximately doubled but tidal amplitudes increased only ∼6%. Modeling shows that increased shipping channel depths from ∼5 to ∼13m drove the observed changes, with other factors like channel shortening and width reduction producing comparatively minor effects. Tidal amplitude increases are spatially variable, with a maximum change 20–25 km from the estuary inlet; tidal theory suggests that increases in amplitude approximately follow , where x is the distance from the ocean and μ is a damping coefficient. Tidal changes are a predictor of altered surge dynamics: Numerical modeling of hurricane Irma under 1898 and 2017 bathymetric conditions confirms that both tidal and storm surge amplitudes are larger today, with a similar spatial pattern. Nonetheless, peak water levels are simulated to be larger under 1898 bathymetry. The cause is likely the record river discharge observed during the storm; as suggested by a subtidal water‐level model, channel deepening since 1898 appears to have reduced the average surface slope required to drain both mean river flow and storm flows toward the ocean. Nonetheless, results suggest an increased vulnerability to storms with less river flow, but larger storm surge.

Semi-Supervised Segmentation for Coastal Monitoring Seagrass Using RPA Imagery

Intertidal seagrass plays a vital role in estimating the overall health and dynamics of coastal environments due to its interaction with tidal changes. However, most seagrass habitats around the globe have been in steady decline due to human impacts, disturbing the already delicate balance in the environmental conditions that sustain seagrass. Miniaturization of multi-spectral sensors has facilitated very high resolution mapping of seagrass meadows, which significantly improves the potential for ecologists to monitor changes. In this study, two analytical approaches used for classifying intertidal seagrass habitats are compared—Object-based Image Analysis (OBIA) and Fully Convolutional Neural Networks (FCNNs). Both methods produce pixel-wise classifications in order to create segmented maps. FCNNs are an emerging set of algorithms within Deep Learning. Conversely, OBIA has been a prominent solution within this field, with many studies leveraging in-situ data and multiresolution segmentation to create habitat maps. This work demonstrates the utility of FCNNs in a semi-supervised setting to map seagrass and other coastal features from an optical drone survey conducted at Budle Bay, Northumberland, England. Semi-supervision is also an emerging field within Deep Learning that has practical benefits of achieving state of the art results using only subsets of labelled data. This is especially beneficial for remote sensing applications where in-situ data is an expensive commodity. For our results, we show that FCNNs have comparable performance with the standard OBIA method used by ecologists.

Tidal Flat Extraction and Change Analysis Based on the RF-W Model: A Case Study of Jiaozhou Bay, East China

Coastal tidal flats are important ecological resources. As the dividing line between marine and terrestrial ecosystems, tidal flats provide a large number of ecosystem services. However, with the excessive development of coastal areas, tidal flat resources have been drastically reduced, leading to the deterioration of coastal ecosystems. There is an urgent need to acquire accurate information on the changes in tidal flat resources. This research proposes a tidal flat extraction model (RF-W model) that combines the random forest (RF) method and waterline method, which aims to improve the accuracy of tidal flat extraction. This method can effectively eliminate the shortcomings of the RF method in determining the lower boundary of tidal flats and those of the waterline method in distinguishing river channels and tidal flats. The tidal flat extraction of Qingdao Jiaozhou Bay in 2020 is performed as an example of the model. The results show that the user’s and producer’s accuracies of the RF-W model were both the highest, indicating that the improved model can accurately extract tidal flat information. Then, we used the RF-W model to extract tidal flat information for Jiaozhou Bay in seven periods (1990, 1995, 2000, 2005, 2010, 2015, and 2020) and to study the spatiotemporal changes in the tidal flats and influencing factors from 1990 to 2020. The tidal flat area of Jiaozhou Bay showed an overall downward trend before 2015, and the area decreased by 21.9 km2, with a reduction in the rate of approximately 1.1%/year. After 2015, the tidal flat area rebounded slightly. The overall change in Jiaozhou Bay showed reclamation and expansion toward the sea. The reduction in the sand content of the rivers entering the sea, reclamation and cultivation, and land development were the main factors contributing to the reduction in the tidal flat area in Jiaozhou Bay. In addition, sea level rise due to climate warming is a long-term potential factor.