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Results for “Estuarine and Coastal Marine Science”

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49 records · Page 3Linked to original sources
USGS2011

Spatial and temporal characteristics of grouper spawning aggregations in marine protected areas in Palau, western Micronesia

In Palau, Ngerumekaol and Ebiil Channels are spawning aggregation sites that have been protected from fishing since 1976 and 2000, respectively. Groupers and other targeted fisheries species were monitored monthly over a 1.5 year period at these two spawning aggregations and two nearby exploited reference sites where grouper formerly aggregated to spawn. At the protected aggregation sites, three grouper species ( Plectropomus areolatus , Epinephelus polyphekadion , and Epinephelus fuscoguttatus ) accounted for 78% of the abundance and 85% of the biomass of all resource species surveyed but comprised <1% of the total abundance and biomass at reference sites not protected from fishing that formally harbored spawning aggregations. Abundance and biomass of grouper species pooled were 54% and 72% higher, respectively, at Ngerumekaol compared to Ebiil. Comparisons with data from the same locations in 1995–1996 showed order of magnitude declines in abundance of E. polyphekadion at both locations. The lower numbers of E. fuscoguttatus and the near absence of E. polyphekadion at Ebiil may reflect the effects of previous and current overexploitation.

Palau↗
USGS2019

Mercury speciation and retention in a salt marsh undergoing long-term fertilization

Experimental plots in Great Sippewissett Marsh (Falmouth, MA USA) have been undergoing long-term (>48 years) fertilization through the application of commercial sewage sludge-based fertilizer. The experimental treatment focuses on the effect of added nitrogen on the salt marsh plots, but also supplies mercury (Hg) and other metals. This experiment provides a unique opportunity to test hypotheses regarding the Hg-related response of coastal marine ecosystems to eutrophication as well as assess the efficacy of salt marshes as sinks for increased loadings of Hg to the coastal zone. Hg inventories in sediments of control plots were similar to loadings from atmospheric deposition and inventories in the fertilized plots closely reflected the estimated loadings of Hg contained in the added fertilizer. In both the control and fertilized plots, distribution of Hg appeared somewhat different than the history of loadings, implying some level of Hg mobility. The relative abundance of monomethylmercury (CH 3 Hg + ) within the plots varied with the amount of fertilizer applied with the highest percentage of Hg as CH 3 Hg + found in the control plots, and the lowest percentages of CH 3 Hg + and S were measured in plots fertilized at the highest dose. The results from this marsh suggest that eutrophication indirectly lowers CH 3 Hg + production in this particular ecosystem, but perhaps not as a result of the sequestration of Hg(II) with S.

Estuarine, Coastal and Shelf Science↗
USGS2001

The geology and palynology of lower and Middle Pennsylvanian strata in the Western Kentucky Coal Field

The Western Kentucky Coal Field is the southern tip of the Eastern Interior, or Illinois Basin. Pennsylvanian rocks in this area, which include conglomerate, sandstone, shale, limestone and coal, were deposited primarily in coastal-deltaic settings at a time when western Kentucky was located close to the equator. This paper discusses temporal changes in regional sedimentation patterns and coal-forming floras of Lower and Middle Pennsylvanian strata in the Western Kentucky Coal Field. Lower Pennsylvanian strata of the Caseyville Formation are characterized by paleovalley-filling sedimentation patterns and extabasinal quartz pebbles. Caseyville Formation coals are characterized thin and discontinuous and were strongly influenced by subsidence within underlying paleovalleys, and the dissected lower Pennsylvanian paleotopography. Caseyville coals are commonly dominated by Lycospora, but can also have variable palynofloras, which probably reflects variable edaphic conditions and edge effects within small, patchy paleomires. Tradewater Formation strata show increased marine influences and tidal-estuarine sedimentation, especially in the middle and upper parts. Coal beds in the lower part of the Tradewater typically are thin and discontinuous, although some economically important beds are present. Coals become thicker, more abundant and more laterally persistent towards the top of the formation. Palynologically, lower and middle Tradewater Formation coals are dominated by Lycospora, but begin to show increased amounts of tree fern spores. Middle and upper Tradewater coals are thicker and more continuous, and contain high percentages of tree fern spores. In addition, cordaite pollen is locally abundant in this interval. Carbondale and Shelburn (Desmoinesian) strata are much more laterally continuous, and occur within classic cyclothems that can be traced across the coal field. Cyclothems have long been interpreted as being eustatically driven, and glacio-eustacy controlled not only sedimentation but also the formation of Desmoinesian paleomires. Palynologically, Carbondale and Shelburn coals are either dominated by Lycospora or have heterogeneous palynofloras. Palynologic and coal-quality data suggest that hydrologic base level may have been the primary control on Desmoinesian paleomires, rather than paleoclimate, as the coals display rheotrophic, rather than ombrotrophic characteristics. ?? 2001 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2018

Vibrio population dynamics in Mid-Atlantic surface waters during Saharan dust events

Vibrio is a cosmopolitan genus of marine bacteria, highly investigated in coastal and estuarine environments. Vibrio have also been isolated from pelagic waters, yet very little is known about the ecology of these oligotrophic species. In this study we examined the relative change in bacterial abundance and more specifically the dynamics of Vibrio in the tropical North Atlantic in response to the arrival of pulses of Saharan dust aerosols, a major source of biologically important nutrients for downwind marine surface waters. Aerosol and surface water samples were collected over 1 month coinciding with at least two distinct dust events. Total bacterial counts increased by 1.6-fold correlating with the arrival of Saharan dust ( r = 0.76; p = 0.001). Virus-like particles (VLP) also followed this trend and were correlated with bacterial counts ( r = 0.67; p = 0.01). Vibrio specific qPCR targeting the 16S rRNA gene ranged from below detection limits to a high of 9,145 gene copies ml −1 with the arrival of dust. This increase equated to 6.5 × 10 2 −1.5 × 10 3 individual genome equivalents ml −1 based on the known range of 16S rRNA copies among this genus. Vibrio exhibited bloom-bust cycles potentially attributed to selective viral lysis or bloom depletion of organic carbon. This work is one of the few studies to examine the open ocean ecology of Vibrio , a conditionally rare taxon, whose bloom-bust lifestyle likely is a contributing factor in the flow of nutrients and energy in pelagic ecosystems.

Frontiers in Marine Science↗
USGS2025

Shifts in marsh erosion, migration, and wave exposure over nearly two centuries of sea-level rise in the Gulf of Mexico

Coastal wetlands are economically important ecosystems, but are at risk to erosion from waves, storms, and sea level rise. However, marshes can persist under rising sea level through vertical accretion and migration into adjacent higher-elevation habitats. We measured rates of marsh shoreline change and migration and compared the results for historical and modern periods in a largely undeveloped and marine-dominated estuary within the Mississippi-Alabama coast of the Northern Gulf of Mexico. Mean shoreline change rate for the modern (post-1957) period was higher than historical rates (pre-1957) at −1.55 ± 0.11 m yr −1 and -0.84 ± 0.07 m yr −1 , respectively. Shoreline change rates were highest in regions where exposure to wind-driven waves increased due to barrier island migration and land loss. Marsh migration (modern 1.25 ± 0.37 m yr −1 and historical 1.01 ± 0.13 m yr −1 ) occurred at similar rates as shoreline erosion except for the highest erosive shorelines, leading to an overall 15% marsh loss. Upland-to-marsh conversion occurred in forested areas and may have been encouraged by changes in management practices. In the Grand Bay estuary, our data show that marsh migration is not occurring at sufficient rates to compensate for marsh loss, resulting in overall loss in marsh habitat. Overall, migration may allow marsh to persist under rising sea levels but can lead to an overall reduction in forested or freshwater habitats if steep slopes or other barriers prevent their migration.

Alabama, Mississippi↗
USGS2019

Tidal variation in cohesive sediment distribution in an idealized, partially-mixed estuary

Particle settling velocity and erodibility are key factors that govern the transport of sediment through coastal environments including estuaries. These are difficult to parameterize in models that represent mud, whose properties can change in response to many factors, including tidally varying suspended sediment concentration (SSC) and shear stress. Using the COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) model framework, we implemented bed consolidation, sediment-induced stratification, and flocculation formulations within an idealized two-dimensional domain that represented the longitudinal dimension of a micro-tidal, muddy, partially mixed estuary. Within the Estuarine Turbidity Maximum (ETM), SSC and median floc diameter varied by a factor of four over the tidal cycle. Downstream of the ETM, the median floc size and SSC were several times smaller and showed less tidal variation (~20% or less). The suspended floc distributions only reached an equilibrium size as a function of SSC and shear in the ETM at peak tidal flow. In general, flocculation increased particle size, which reduced SSC by half in the ETM through increased settling velocity. Consolidation also limited SSC by reduced resuspension, which then limited floc growth through reduced SSC by half outside of the ETM. Sediment-induced stratification had negligible effects in the parameter space examined. Efforts to lessen the computation cost of the flocculation routine by reducing the number of size classes proved difficult; floc size distribution and SSC were sensitive to specification of size classes by factors of 60% and 300%, respectively.

Virginia↗
USGS1991

Pliocene-Pleistocene coastal events and history along the western margin of Australia

Coastal deposits along the western coastal margin of Australia, a region of relative tectonic stability, record Plio-Pleistocene events and processes affecting the inner shelf and adjacent hinterland. Tectonic deformation of these deposits is more apparent in the Carnarvon Basin, and rather less so in the Perth Basin. The most complete record comes from the Perth Basin, where units of Pliocene and Pleistocene ages are well represented. In the Perth Basin, the predominantly siliciclastic Yoganup Formation, Ascot Formation and Bassendean Sand represent a complex of shoreline, inner shelf and regressive-dune facies equivalents, the deposition of which began at an undetermined stage of the Pliocene, through to the Early Pleistocene. The deposition of this sequence closed with a major regression and significant faunal extinction. Bioclastic carbonates characterize the Middle and Late Pleistocene of the Perth and Carnarvon basins. Fossil assemblages include a distinct subtropical element, unknown from the Ascot Formation and suggesting a strengthening of the Leeuwin Current. The estuarine arcoid bivalve Anadara trapezia characterizes assemblages of Oxygen Isotope Stages 5 and 7 in the Perth and Carnarvon basins, where it is now extinct. Deposits of Substage 5e (Perth Basin) also record a southerly expansion of warm-water corals and other fauna consistent with shelf temperatures warmer than present. New uranium-series ages on corals from marine sequences of the Tantabiddi Member, of the Bundera Calcarenite of the western Cape Range are consistent with the ‘double peak’ hypothesis for levels of Substage 5e but the evidence remains less than conclusive. Initial uranium-series dates from the Bibra and Dampier formations of Shark Bay indicate that both derive from the Late Pleistocene. These numerical ages contradict previous interpretations of relative ages obtained from field studies. The age relationship of the units requires further investigation.

Quaternary Science Reviews↗
USGS2018

Juvenile Chinook salmon and forage fish use of eelgrass habitats in a diked and channelized Puget Sound River Delta

Eelgrass Zostera marina can form extensive meadows on Puget Sound river deltas. The extent to which these meadows provide critical rearing habitat for local estuarine fishes, especially out‐migrating juvenile salmon, is not well understood. Further, delta eelgrass has been impacted by diking and river channelization with unknown consequences for fish. We sampled fish in the Skagit River delta, Washington, during April–September with a lampara net, which is well suited to capturing fish in eelgrass. We compared abundance and body size of Chinook Salmon Oncorhynchus tshawytscha and three forage fish species between eelgrass and nearby unvegetated habitat. We also assessed combined effects of eelgrass characteristics (meadow size and morphology) and oceanographic conditions (temperature and salinity), which covaried according to proximity and orientation to channelized distributary outlets, diked shorelines, and a jetty. Chinook Salmon were more abundant in eelgrass than in unvegetated habitat in June–July and were relatively more abundant in eelgrass compared with unvegetated habitat in regions with intact eelgrass than offshore from a channelized distributary outlet. Abundances of Pacific Herring Clupea pallasii and Shiner Perch Cymatogaster aggregata were consistently severalfold higher in eelgrass than in unvegetated habitat. Surf Smelt Hypomesus pretiosus were more abundant in eelgrass than in unvegetated habitat at some locations, but never less abundant in eelgrass. Our results suggest that conservation and restoration of delta eelgrass would benefit these species and help to identify the settings in which these actions would be most beneficial.

Washington↗
USGS2021

Activity patterns of anadromous fish below a tide gate: Observations from high‐resolution imaging sonar

The construction of dams and tide gates on waterways has altered the physical structure of many coastal, estuarine, and freshwater systems. These changes have come at a cost to fish populations, most notably diadromous species, which rely on connectivity between marine and freshwater systems. These anthropogenic structures can have direct effects on migrating fish, such as blocking fish passage, or have more subtle effects, such as changing movement patterns. This study used a high‐resolution Adaptive Resolution Imaging Sonar to examine the behavior of Striped Bass Morone saxatilis , a large coastal predator, and Alewife Alosa pseudoharengus and Blueback Herring Alosa aestivalis (collectively known as river herring), which are forage fish, below a tide gate structure on the Herring River in Wellfleet, Massachusetts, during the river herring spring spawning run. Striped Bass were persistently present downstream of the tide gate and exhibited strong diurnal and tidal patterns. Activity of Striped Bass was highest at night and during ebb tides. During peak outflow periods, river herring were observed milling downstream of the dam in a scour pool, indicating delayed upstream passage. River herring upstream migration was primarily associated with daytime and during incoming tides. Downstream‐migrating river herring were primarily observed during nighttime hours. While it was documented that the tide gates provided a physical impediment to migration, their effect on predator behavior could pose an additional challenge to migrating river herring, further complicating their recovery efforts. Due to the prevalence of obstructed waterways, studying the behavior of fish around anthropogenic structures is important in understanding the full range of impacts that these systems have under varying ecological conditions and on ecological relationships.

Massachusetts↗
USGS2019

Fish assemblage structure and fisheries resources in Puerto Rico’s riverine estuaries

Tropical estuaries are diverse and productive habitats with respect to their fish assemblages and associated fisheries, but these ecosystems and fisheries are imperiled by multiple anthropogenic threats. Despite the economic, social, and biodiversity value of tropical estuarine fish assemblages, they are poorly understood, especially those on Caribbean islands. We sampled the fish assemblages of four estuaries that were broadly representative of riverine estuaries in Puerto Rico, including the Río Grande de Arecibo, Río Espiritu Santo, Río Mameyes, and Río Sabana. We used a combination of passive (gill nets) and active (seine) gears at locations that spanned the salinity gradient of each estuary during July–October 2013–2014 (rainy season) and March 2015 (dry season). Fish species richness among the riverine estuaries varied from 18 to 29 and was highest in the Río Espiritu Santo estuary. Nonmetric multidimensional scaling differentiated fish assemblages among estuaries but not by season or consistently by location within an estuary. Spearman's rank correlation analysis also revealed dissimilarity among each estuary's fish assemblage, as most pairwise correlations between the species compositions were not significant. We identified common and widespread species among estuaries, including sport fishes, such as the Tarpon Megalops atlanticus and Common Snook Centropomus undecimalis . As the only multi‐river assessment of riverine estuary fish assemblages in Puerto Rico, our results provide the best available information about the spatial variability of assemblages and fisheries resources. This information will benefit future conservation and fisheries management efforts, which are needed due to increasing anthropogenic impacts, such as illegal harvest, invasive species, and water diversions.

Puerto Rico↗
USGS2023

Two centuries of southwest Iceland annually-resolved marine temperature reconstructed from Arctica islandica shells

Iceland's exposure to major ocean current pathways of the central North Atlantic makes it a useful location for developing long-term proxy records of past marine climate. Such records provide more detailed understanding of the full range of past variability which is necessary to improve predictions of future changes. We constructed a 225-year (1791–2015 CE) master shell growth chronology from 29 shells of Arctica islandica collected at 100 m water depth in southwest Iceland (Faxaflói). The growth chronology provides a robust age model for shell oxygen isotope (δ 18 O shell ) data produced at annual resolution for 251 years (1765–2015 CE). The temperature reconstruction derived from δ 18 O shell shows coherence with May–October local surface temperature records and sea surface temperatures in the North Atlantic region, suggesting it is a useful proxy indicator of water temperature variability at 100 m depth within Faxaflói. Field correlations between the shell-based records and gridded sea surface temperature data reveal strong positive correlations between the 1-year lagged shell growth and temperatures within the subpolar gyre post-1972, suggesting a delayed influence of subpolar gyre dynamics on ecological indicators in southwest Iceland in recent decades. However, the shell growth chronology and δ 18 O shell record generally show relatively weak and insignificant correlations with larger region climate indices including the Atlantic Multidecadal Variability, North Atlantic Oscillation, and East Atlantic pattern. Therefore the interannual variations in the newly produced shell-based records appear to reflect more local to regional dynamics around southwest Iceland than large-scale modes of climate variability.

Estuarine, Coastal and Shelf Science↗
USGS2024

Nutrient and carbonate chemistry patterns associated with Karenia brevis blooms in three West Florida Shelf estuaries 2020-2023

Ocean acidification (OA) driven by eutrophication, riverine discharge, and other threats from local population growth that affect the inorganic carbonate system is already affecting the eastern Gulf of Mexico. Long-term declines in pH of ~ -0.001 pH units yr -1 have been observed in many southwest Florida estuaries over the past few decades. Coastal and estuarine waters of southwest Florida experience high biomass harmful algal blooms (HABs) of the dinoflagellate Karenia brevis nearly every year; and these blooms have the potential to impact and be impacted by seasonal to interannual patterns of carbonate chemistry. Sampling was conducted seasonally along three estuarine transects (Tampa Bay, Charlotte Harbor, Caloosahatchee River) between May 2020 and May 2023 to obtain baseline measurements of carbonate chemistry prior to, during, and following K. brevis blooms. Conductivity, temperature and depth data and discrete water samples for K. brevis cell abundance, nutrients, and carbonate chemistry (total alkalinity, dissolved inorganic carbonate (DIC), p CO 2, and pH T were evaluated to identify seasonal patterns and linkages among carbonate system variables, nutrients, and K. brevis blooms. Karenia brevis blooms were observed during six samplings, and highest p CO 2 and lowest pH T was observed either during or after blooms in all three estuaries. Highest average pH and lowest p CO 2 were observed in Tampa Bay. In all three estuaries, average DIC and pH T were higher and p CO 2 was lower during dry seasons than wet seasons. There was strong influence of net community calcification (NCC) and net community production (NCP) on the carbonate system; and NCC : NCP ratios in Tampa Bay, Charlotte Harbor, and the Caloosahatchee River were 0.83, 0.93, and 1.02, respectively. Linear relationships between salinity and dissolved ammonium, phosphate, and nitrate indicate strong influence of freshwater inflow from river input and discharge events on nutrient concentrations. This study is a first step towards connecting observations of high biomass blooms like those caused by K. brevis and alterations of carbonate chemistry in Southwest Florida. Our study demonstrates the need for integrated monitoring to improve understanding of interactions among the carbonate system, HABs, water quality, and acidification over local to regional spatial scales and event to decadal time scales.

Florida↗
USGS2003

The fate of wastewater-derived nitrate in the subsurface of the Florida Keys: Key Colony Beach, Florida

Shallow injection is the predominant mode of wastewater disposal for most tourist-oriented facilities and some residential communities in the US Florida Keys National Marine Sanctuary. Concern has been expressed that wastewater nutrients may be escaping from the saline groundwater system into canals and surrounding coastal waters and perhaps to the reef tract 10 km offshore, promoting unwanted algal growth and degradation of water quality. We performed a field study of the fate of wastewater-derived nitrate in the subsurface of a Florida Keys residential community (Key Colony Beach, FL) that uses this disposal method, analyzing samples from 21 monitoring wells and two canal sites. The results indicate that wastewater injection at 18–27 m depth into saline groundwater creates a large buoyant plume that flows quickly (within days) upward to a confining layer 6 m below the surface, and then in a fast flow path toward a canal 200 m to the east within a period of weeks to months. Low-salinity groundwaters along the fast flow path have nitrate concentrations that are not significantly reduced from that of the injected wastewaters (ranging from 400 to 600 μmol kg −1 ). Portions of the low-salinity plume off the main axis of flow have relatively long residence times (>2 months) and have had their nitrate concentrations strongly reduced by a combination of mixing and denitrification. These waters have dissolved N 2 concentrations up to 1.6 times air-saturation values with δ 15 N[N 2 ]=0.5-5‰, δ 15 N[NO 3 - ]=16-26‰, and calculated isotope fractionation factors of about −12±4‰, consistent with denitrification as the predominant nitrate reduction reaction. Estimated rates of denitrification of wastewater in the aquifer are of the order of 4 μmol kg -1 N day -1 or 0.008 day -1 . The data indicate that denitrification reduces the nitrate load of the injected wastewater substantially, but not completely, before it discharges to nearby canals.

Florida↗