Estuaries are under threat globally from a wide range of stressors, with rates of ecosystem metabolism – respiration (R), gross primary production (GPP), and net ecosystem metabolism (NEM) – representing a way for resource managers to quantify their impacts. In this study, we assessed how natural and anthropogenic stressors have altered metabolism within the extensively modified Sacramento-San Joaquin Delta (“Delta”) in California, USA. Metabolism was estimated using a diel open-water technique utilizing dissolved oxygen measurements from a high frequency (15 min) water quality monitoring array, and spanned 6 sites across 11 years (2014–2025). Our analyses were driven by a conceptual model of Delta carbon (C) cycling focused on 1) Invasive aquatic vegetation (IAV), 2) Phytoplankton, 3) Wastewater treatment plant (WWTP) upgrades, 4) Large-scale flow alterations, and 5) Wet vs. dry years. We found that allochthonous C fuels net heterotrophy in the outer riverine sections of the Delta, while the heavily vegetated central Delta produces autochthonous C remineralized elsewhere in the system. IAV were the dominant primary producers, with low phytoplankton production except during a historic bloom. WWTP upgrades imparted negligible changes to metabolism, with low chlorophyll a (< 5 µg L−1) both before and after. Introduction of a flow barrier – a management response to drought – hydrodynamically isolated deep-water channels from nearby shallow areas, resulting in decreased metabolism indicative of changes to C transport. Contrary to past research, low rainfall years were associated with increased metabolism. This study demonstrates how multi-sensor arrays can be used to quantify ecosystem responses to major environmental stressors.
In 2016, marsh spits along Fowl River - an oligohaline estuary in coastal Alabama, USA - were identified by community members as a top restoration priority for the Mobile Bay National Estuary Program (MBNEP). To guide a directed restoration program, scientists, resource managers, engineers, and community members needed an improved understanding of the stressors underlying marsh degradation. The Fowl River Marsh Health Study (FRMHS) was conducted by an interdisciplinary team to assess factors influencing marsh loss and inform future restoration management decisions in the watershed. Results from the FRMHS indicated that chronic inundation from sea level rise (SLR; average water level > 5–10 cm above marsh surface), low accretion rates (avg 1.15 mm/yr), saltwater intrusion, and boat wake energy (> 20
Sustainable management of lagoon fisheries requires an integrated assessment of ecological and human dimensions. Pulicat Lagoon, India’s second-largest brackishwater lagoon, supports diverse fisheries and livelihoods but faces threats from anthropogenic activities and environmental degradation. This study applied the modified Rapid Appraisal for Fisheries (RAPFISH) framework to evaluate the sustainability status of Pulicat Lagoon fisheries using a multi-dimensional, indicator-based approach. The ten major fisheries were assessed across five dimensions: ecological, economic, social, technological, and governance based on 34 indicators. Sustainability scores were estimated using multi-dimensional scaling, supported by leverage analysis to identify influential indicators. The overall sustainability score of Pulicat Lagoon fisheries was 47.50
Mangrove forests are important blue-carbon ecosystems, yet carbon stocks in small-island mangroves remain poorly characterized. We quantified vegetation, sediment, and total ecosystem carbon stocks (TECS) in mangrove forests across three island municipalities in Tawi-Tawi, southwestern Philippines. Bongao forms part of a larger island complex that includes relatively sheltered mangrove settings, whereas Simunul and Sibutu are characterized predominantly by fringing mangroves along more open coasts. We hypothesized that TECS would vary among municipalities with different forest characteristics and coastal settings, with sediment carbon constituting the dominant carbon pool. Mangrove structure and species composition were assessed through vegetation surveys. Vegetation carbon stocks (VCS) were estimated using species- or genus-specific allometric equations and sediment carbon stocks (SCS) were determined from sediment cores using the loss-on-ignition (LOI) method. Fourteen species representing eight genera were recorded, with species composition varying among municipalities. Mean VCS was highest in Simunul, whereas mean SCS was highest in Bongao, indicating contrasting spatial patterns between carbon pools. TECS, calculated using SCS from the full recovered sediment profiles (40–90 cm), ranged from 91 to 495 Mg C ha⁻¹, with the highest value recorded in Bongao. Sediment carbon accounted for 85–98
Impacts of generalist invaders are often discussed as species-level effects, but the trophic interactions that produce those effects are local. We dissected and visually examined stomach contents from 271 European green crabs (Carcinus maenas) collected from 21 sampling groups in the Plum Island estuary, Massachusetts, during June–July 2025. We compared the occurrence of foods across marsh-associated primary creeks, main-stem channels, and the open sound. Algal or plant material occurred in 85.2
