Support for Integrated Ecosystem Assessments of NOAA’s National Estuarine Research Reserves System (NERRS), Volume I: The Impacts of Coastal Development on the Ecology and Human Well-being of Tidal Creek Ecosystems of the US Southeast

A study was conducted, in association with the Sapelo Island and North Carolina National Estuarine Research Reserves (NERRs), to evaluate the impacts of coastal development on sentinel habitats (e.g., tidal creek ecosystems), including potential impacts to human health and well-being. Uplands associated with southeastern tidal creeks and the salt marshes they drain are popular locations for building homes, resorts, and recreational facilities because of the high quality of life and mild climate associated with these environments. Tidal creeks form part of the estuarine ecosystem characterized by high biological productivity, great ecological value, complex environmental gradients, and numerous interconnected processes. This research combined a watershed-level study integrating ecological, public health and human dimension attributes with watershed-level land use data. The approach used for this research was based upon a comparative watershed and ecosystem approach that sampled tidal creek networks draining developed watersheds (e.g., suburban, urban, and industrial) as well as undeveloped sites. The primary objective of this work was to clearly define the relationships between coastal development with its concomitant land use changes and non-point source pollution loading and the ecological and human health and well-being status of tidal creek ecosystems. Nineteen tidal creek systems, located along the southeastern United States coast from southern North Carolina to southern Georgia, were sampled during summer (June-August), 2005 and 2006. Within each system, creeks were divided into two primary segments based upon tidal zoning: intertidal (i.e., shallow, narrow headwater sections) and subtidal (i.e., deeper and wider sections), and watersheds were delineated for each segment. In total, we report findings on 24 intertidal and 19 subtidal creeks. Indicators sampled throughout each creek included water quality (e.g., dissolved oxygen concentration, salinity, nutrients, chlorophyll-a levels), sediment quality (e.g., characteristics, contaminants levels including emerging contaminants), pathogen and viral indicators, and abundance and genetic responses of biological resources (e.g., macrobenthic and nektonic communities, shellfish tissue contaminants, oyster microarray responses). For many indicators, the intertidally-dominated or headwater portions of tidal creeks were found to respond differently than the subtidally-dominated or larger and deeper portions of tidal creeks. Study results indicate that the integrity and productivity of headwater tidal creeks were impaired by land use changes and associated non-point source pollution, suggesting these habitats are valuable early warning sentinels of ensuing ecological impacts and potential public health threats. For these headwater creeks, this research has assisted the validation of a previously developed conceptual model for the southeastern US region. This conceptual model identified adverse changes that generally occurred in the physical and chemical environment (e.g., water quality indicators such as indicator bacteria for sewage pollution or sediment chemical contamination) when impervious cover levels in the watershed reach 10-20%. Ecological characteristics responded and were generally impaired when impervious cover levels exceed 20-30%. Estimates of impervious cover levels defining where human uses are impaired are currently being determined, but it appears that shellfish bed closures and the flooding vulnerability of headwater regions become a concern when impervious cover values exceed 10-30%. This information can be used to forecast the impacts of changing land use patterns on tidal creek environmental quality as well as associated human health and well-being. In addition, this study applied tools and technologies that are adaptable, transferable, and repeatable among the high quality NERRS sites as comparable reference entities to other nearby developed coastal watersheds. The findings herein will be of value in addressing local, regional and national needs for understanding multiple stressor (anthropogenic and human impacts) effects upon estuarine ecosystems and response trends in ecosystem condition with changing coastal impacts (i.e., development, climate change). (PDF contaions 88 pages)

Tidal creek habitats: sentinels of coastal health

Tidal creek ecosystems are the primary aquatic link between stormwater runoff form the land and estuaries. Small tidal creeks begin in upland areas and drain into larger creeks forming a network. The creeks increase in size until they join a tidal river, sound, bay, or harbor that ultimately conect to the coastal ocean. The upper regions or headwaters of tidal creeks are "first responders" to stormwater runoff and are an important habitat for evaluating the impacts of coastal development on aquatic ecosystems. (PDF contains 22 pages)

Fish assemblages found in tidal-creek and seagrass habitats in the Suwannee River estuary

Fish assemblages were investigated in tidal-creek and seagrass habitats in the Suwannee River estuary, Florida. A total of 91,571 fish representing 43 families were collected in monthly seine samples from January 1997 to December 1999. Tidal creeks supported greater densities of fish (3.89 fish/m2; 83% of total) than did seagrass habitats (0.93 fish/m2). We identified three distinct fish assemblages in each habitat: winter−spring, summer, and fall. Pinfish (Lagodon rhomboides), pigfish (Orthopristis chrysoptera), and syngnathids characterized seagrass assemblages, whereas spot (Leiostomus xanthurus), bay anchovy (Anchoa mitchilli), silversides (Menidia spp.), mojarras (Eucinostomus spp.), and fundulids characterized tidal-creek habitats. Important recreational and commercial species such as striped mullet (Mugil cephalus) and red drum (Sciaenops ocellatus) were found primarily in tidal creeks and were among the top 13 taxa in the fish assemblages found in the tidal-creek habitats. Tidal-creek and seagrass habitats in the Suwannee River estuary were found to support diverse fish assemblages. Seasonal patterns in occurrence, which were found to be associated with recruitment of early-life-history stages, were observed for many of the fish species.

Geomorphic and hydrodynamic responses in salt marsh-tidal creek systems, Jiangsu, China

Salt marsh-tidal creek systems as a coastal geomorphological unit represent an important natural resource. The present study on Jiangsu salt marshes, eastern China, shows that variations in tidal current velocities in salt marsh creeks are controlled by the local tidal wave characteristics and the bed slope and elevation of the salt marshes and creeks. Likewise, the tidal currents modify the geomorphology of the salt marsh-tidal creek systems by transporting sediments and causing erosion/deposition. Storm events, which appear to have cyclical changes in their intensity relating to sunspot activities, can affect the geomorphic evolution of such systems. Further, in response to accelerated sea-level rise, accretional rates on salt marshes may increase. The tidal creeks have the function of transporting water and sediment onto the salt marsh surface; further, the energy of tidal currents and waves are dissipated within the salt marsh-tidal creek system. Hence, this coastal system has a potential value for coastal protection.

A tidal creek water budget: Estimation of groundwater discharge and overland flow using hydrologic modeling in the Southern Everglades

Taylor Slough is one of the natural freshwater contributors to Florida Bay through a network of microtidal creeks crossing the Everglades Mangrove Ecotone Region (EMER). The EMER ecological function is critical since it mediates freshwater and nutrient inputs and controls the water quality in Eastern Florida Bay. Furthermore, this region is vulnerable to changing hydrodynamics and nutrient loadings as a result of upstream freshwater management practices proposed by the Comprehensive Everglades Restoration Program (CERP), currently the largest wetland restoration project in the USA. Despite the hydrological importance of Taylor Slough in the water budget of Florida Bay, there are no fine scale (∼1 km2) hydrodynamic models of this system that can be utilized as a tool to evaluate potential changes in water flow, salinity, and water quality. Taylor River is one of the major creeks draining Taylor Slough freshwater into Florida Bay. We performed a water budget analysis for the Taylor River area, based on long-term hydrologic data (1999–2007) and supplemented by hydrodynamic modeling using a MIKE FLOOD (DHI,http://dhigroup.com/) model to evaluate groundwater and overland water discharges. The seasonal hydrologic characteristics are very distinctive (average Taylor River wet vs. dry season outflow was 6 to 1 during 1999–2006) with a pronounced interannual variability of flow. The water budget shows a net dominance of through flow in the tidal mixing zone, while local precipitation and evapotranspiration play only a secondary role, at least in the wet season. During the dry season, the tidal flood reaches the upstream boundary of the study area during approximately 80 days per year on average. The groundwater field measurements indicate a mostly upwards-oriented leakage, which possibly equals the evapotranspiration term. The model results suggest a high importance of groundwater contribution to the water salinity in the EMER. The model performance is satisfactory during the dry season where surface flow in the area is confined to the Taylor River channel. The model also provided guidance on the importance of capturing the overland flow component, which enters the area as sheet flow during the rainy season. Overall, the modeling approach is suitable to reach better understanding of the water budget in the mangrove region. However, more detailed field data is needed to ascertain model predictions by further calibrating overland flow parameters.

Jay Sah crossing tidal creek to measure tree damage by Hurricane Wilma, Harney River

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. This image is made available for non-commercial or educational use only.

Gulf of Mexico tidal creeks serve as sentinel habitats for assessing the impact of coastal development on ecosystem health

A study was conducted, in association with the Alabama and Mississippi National Estuarine Research Reserves (NERRs) in the Gulf of Mexico (GoM) as well as the Georgia, South Carolina, and North Carolina NERRs in the Southeast (SE), to evaluate the impacts of coastal development on tidal creek sentinel habitats, including potential impacts to human health and well-being. Uplands associated with Southeast and Gulf of Mexico tidal creeks, and the salt marshes they drain, are popular locations for building homes, resorts, and recreational facilities because of the high quality of life and mild climate associated with these environments. Tidal creeks form part of the estuarine ecosystem characterized by high biological productivity, great ecological value, complex environmental gradients, and numerous interconnected processes. This research combined a watershed-level study integrating ecological, public health and human dimension attributes with watershed-level land cover data. The approach used for this research was based upon a comparative watershed and ecosystem approach that sampled tidal creek networks draining developed watersheds (e.g., suburban, urban, and industrial) as well as undeveloped sites (Holland et al. 2004, Sanger et al. 2008). The primary objective of this work was to define the relationships between coastal development with its concomitant land cover changes, and non-point source pollution loading and the ecological and human health and wellbeing status of tidal creek ecosystems. Nineteen tidal creek systems, located along the Southeastern United States coast from southern North Carolina to southern Georgia, and five Gulf of Mexico systems from Alabama and Mississippi were sampled during summer (June-August) 2005, 2006 (SE) and 2008 (GoM). Within each system, creeks were divided into two primary segments based upon tidal zoning: intertidal (i.e., shallow, narrow headwater sections) and subtidal (i.e., deeper and wider sections), and watersheds were delineated for each segment. In total, we report findings on 29 intertidal and 24 subtidal creeks. Indicators sampled throughout each creek included water quality (e.g., dissolved oxygen, salinity, nutrients, chlorophyll-a levels), sediment quality (e.g., characteristics, contaminant levels including emerging contaminants), pathogen and viral indicators (e.g., fecal coliform, enterococci, F+ coliphages, F- coliphages), and abundance and tissue contamination of biological resources (e.g., macrobenthic and nektonic communities, shellfish tissue contaminants). Tidal creeks have been identified as a sentinel habitat to assess the impacts of coastal development on estuarine areas in the southeastern US. A conceptual model for tidal creeks in the southeastern US identifies that human alterations (stressors) of upland in a watershed such as increased impervious cover will lead to changes in the physical and chemical environment such as microbial and nutrient pollution (exposures), of a receiving water body which then lead to changes in the living resources (responses). The overall objective of this study is to evaluate the applicability of the current tidal creek classification framework and conceptual model linking tidal creek ecological condition to potential impacts of development and urban growth on ecosystem value and function in the Gulf of Mexico US in collaboration with Gulf of Mexico NERR sites. The conceptual model was validated for the Gulf of Mexico US tidal creeks. The tidal creek classification system developed for the southeastern US could be applied to the Gulf of Mexico tidal creeks; however, some differences were found that warrant further examination. In particular, pollutants appeared to translate further downstream in the Gulf of Mexico US compared to the southeastern US. These differences are likely the result of the morphological and oceanographic differences between the two regions. Tidal creeks appear to serve as sentinel habitats to provide an early warning of the ensuing harm to the larger ecosystem in both the Southeastern and Gulf of Mexico US tidal creeks.

Individual growth rates and movement of juvenile white shrimp (Litopenaeus setiferus) in a tidal marsh nursery

We measured growth and movements of individually marked free-ranging juvenile white shrimp (Litopenaeus setiferus) in tidal creek subsystems of the Duplin River, Sapelo Island, Georgia. Over a period of two years, 15,974 juvenile shrimp (40−80 mm TL) were marked internally with uniquely coded microwire tags and released in the shallow upper reaches of four salt marsh tidal creeks. Subsequent samples were taken every 3−6 days from channel segments arranged at 200-m intervals along transects extending from the upper to lower reach of each tidal creek. These collections included 201,384 juvenile shrimp, of which 184 were marked recaptures. Recaptured shrimp were at large an average of 3−4 weeks (range: 2−99 days) and were recovered a mean distance of <0.4 km from where they were initially marked. Mean residence times in the creek subsystems ranged from 15.2 to 25.5 days and were estimated from exponential decay functions describing the proportions of marked individuals recaptured with increasing days at large. Residence time was not significantly correlated with creek length (Pearson=−0.316, P=0.684 ), but there was suggestive evidence of positive associations with either intertidal (Pearson r=0.867, P=0.133) or subtidal (Pearson r=0.946, P=0.054) drainage area. Daily mean specific growth rates averaged 0.009 to 0.013 among creeks; mean absolute growth rates ranged from 0.56−0.84 mm/d, and were lower than those previously reported for juvenile penaeids in estuaries of the southeastern United States. Mean individual growth rates were not significantly different between years (t-test, P>0.30) but varied significantly during the season, tending to be greater in July than November. Growth rates were size-dependent, and temporal changes in size distributions rather than temporal variation in physical environmental factors may have accounted for seasonal differences in growth. Growth rates differed between creeks in 1999 (t-test, P<0.015), but not in 1998 (t-test, P>0.5). We suggest that spatial variation in landscape structure associated with access to intertidal resources may have accounted for this apparent interannual difference in growth response.

Aeration for plant root respiration in a tidal marsh

This paper investigates the tidal effects on aeration conditions for plant root respiration in a tidal marsh. We extend the work of Ursino et al. ( 2004) by using a two-phase model for air and water flows in the marsh. Simulations have been conducted to examine directly the link between the airflow dynamics and the aeration condition in the marsh soil. The results show that the effects of entrapped air on water movement in the vadose zone are significant in certain circumstances. Single-phase models based on Richards' equation, which neglect such effects, may not be adequate for quantifying the aeration condition in tidal marsh. The optimal aeration condition, represented by the maximum of the integral magnitude of tidally advected air mass ( TAAM) flux, is found to occur near the tidal creek for the four soil textures simulated. This may explain the observation that some salt marsh plant species grow better near tidal creeks than in the inner marsh areas. Our analyses, based on the two-phase model and predicted TAAM flux magnitude, provide further insight into the positive feedback'' mechanism proposed by Ursino et al. ( 2004). That is, pioneer plants may grow successfully near the creek where the root aeration condition is optimal. The roots of the pioneer plants can soften and loosen the rhizosphere soil, which increases the evapotranspiration rate, the soil porosity, and absolute permeability and weakens the capillary effects. These, in turn, improve further the root aeration conditions and may lead to colonization by plants less resistant to anaerobic conditions.

Water quality and harmful algae in Southeastern coastal stormwater ponds

Several long-term monitoring studies describing the water quality and biological condition of Southeastern estuaries (National Estuarine Eutrophication Assessment Project, South Carolina Estuarine and Coastal Assessment Program (SCECAP), Environmental Monitoring and Assessment Program (EMAP), South Carolina Harmful Algal Bloom Program (SCHAB), South Carolina Tidal Creek Project, and others) have been developed. Many of the same water quality issues determined for open estuaries are also found in coastal stormwater ponds, and there are important interactions between the man-made ponds and the natural systems. Researchers have highlighted problems such as nutrient eutrophication, bacterial and chemical contamination, hypoxia, and harmful algal blooms (HABs). This technical memorandum summarizes the state-of-the-knowledge of water quality indicators (dissolved oxygen, nutrients, and chlorophyll a), and harmful algae in Southeastern coastal stormwater ponds. (PDF contains 31 pages)

Biodeposition and Biogeochemical Processes in Shallow, Mesohaline Sediments of Chesapeake Bay

Stocks of the eastern oyster, Crassostrea virginica, have been declining in Chesapeake Bay since the late 19th century, and current strategies involve restoring culture of Crassostrea virginica on-bottom and in devices suspended within the water column. Sub-tidal suspension culture of Crassostrea virginica in Chesapeake Bay occurs mostly in sheltered inlets and tidal creeks and, thereby, has the potential to influence shallow water biogeochemical processes. To assess the influence of Crassostrea virginica biodeposits and benthic microalgae on sediment nitrogen and phosphorus exchange, field studies with Crassostrea virginica held in aquaculture floats and laboratory experiments were conducted. Enhanced organic nitrogen deposition from Crassostrea virginica biodeposits led to gradual increases in surface sediment nitrogen and pore water ammonium concentrations; however, modifications to pore water concentrations were not always expressed at the sediment-water interface. Benthic microalgae often modulated the influence of biodeposits on sediment nitrogen exchange but, as observed in laboratory experiments, the supply of nitrogen from Crassostrea virginica biodeposits may exceed their biological demand. Organic carbon from biodeposits had varying influences on aerobic respiration but consistently stimulated anaerobic metabolism. Shifts in net phosphorus exchange were driven by this anaerobic remineralization and concentrations of iron and manganese oxy(hydr)oxides, with transitions in fluxes coinciding with changes in benthic photosynthesis and oxidation of surface sediments. Manganese and iron oxy(hydr)oxides from biodeposits supported incorporation of added phosphorus and prevented exchange at the sediment-water interface in the absence of iron-sulfide mineral formation. Differences in the response of shallow water sediments to Crassostrea virginica biodeposits were due to the quality and quantity of biodeposits supplied, as well as the spatial and temporal variability within these sediments. Initial conditions and corresponding reference sediments illustrated the potential for sediment biogeochemistry and nutrient exchange from tidal creek sediments to vary spatially and temporally on relatively small scales. Factors influencing variability within tidal creek sediments were related to shifts in riverine freshwater inputs, macroalgal blooms, nutrient concentrations in overlying waters, and bioirrigation from the clam, Macoma balthica.

Paleoenvironmental reconstruction of the coastal Monte Léon and Santa Cruz formations (Early Miocene) at Rincón del Buque, Southern Patagonia: A revisited locality

© 2015 Elsevier Ltd.Sedimentological, ichnological and paleontological analyses of the Early Miocene uppermost Monte León Formation and the lower part of the Santa Cruz Formation were carried out in Rincón del Buque (RDB), a fossiliferous locality north of Río Coyle in Santa Cruz Province, Patagonia, Argentina. This locality is of special importance because it contains the basal contact between the Monte Léon (MLF) and the Santa Cruz (SCF) formations and because it preserves a rich fossil assemblage of marine invertebrates and marine trace fossils, and terrestrial vertebrates and plants, which has not been extensively studied. A ~90m-thick section of the MLF and the SCF that crops out at RDB was selected for this study. Eleven facies associations (FA) are described, which are, from base to top: subtidal-intertidal deposits with Crassotrea orbignyi and bioturbation of the Skolithos-Cruziana ichnofacies (FA1); tidal creek deposits with terrestrial fossil mammals and Ophiomorpha isp. burrows (FA2); tidal flat deposits with Glossifungites ichnofacies (FA3); deposits of tidal channels (FA4) and tidal sand flats (FA5) both with and impoverish Skolithos ichnofacies associated; marsh deposits (FA6); tidal point bar deposits recording a depauperate mixture of both the Skolithos and Cruziana ichnofacies (FA7); fluvial channel deposits (FA8); fluvial point bar deposits (FA9); floodplain deposits (FA10); and pyroclastic and volcaniclastic deposits of the floodplain where terrestrial fossil mammal remains occur (FA11).The transition of the MLF-SCF at RDB reflects a changing depositional environment from the outer part of an estuary (FA1) through the central (FA2-6) to inner part of a tide-dominated estuary (FA7). Finally a fluvial system occurs with single channels of relatively low energy and low sinuosity enclosed by a broad, low-energy floodplain dominated by partially edaphized ash-fall, sheet-flood, and overbank deposits (FA8-11). Pyroclastic and volcaniclastic materials throughout the succession must have been deposited as ash-fall distal facies in a fluvial setting and also were carried by fluvial streams and redeposited in both estuarine and fluvial settings. These materials preserve most of the analyzed terrestrial fossil mammals that characterize the Santacrucian age of the RDB's succession. Episodic sedimentation under volcanic influence, high sedimentation rates and a relatively warm and seasonal climate are inferred for the MLF and SCF section.Lateral continuity of the marker horizons at RDB serve for correlation with other coastal localities such as the lower part of the coastal SCF south of Río Coyle (~17.6-17.4Ma) belonging to the Estancia La Costa Member of the SCF.

An eclectic morphostratigraphic model for the sedimentary response to Holocene sea-level rise in northwest Europe

The improved empirical understanding of silt facies in Holocene coastal sequences provided by such as diatom, foraminifera, ostracode and testate amoebae analysis, combined with insights from quantitative stratigraphic and hydraulic simulations, has led to an inclusive, integrated model for the palaeogeomorphology, stratigraphy, lithofacies and biofacies of northwest European Holocene coastal lowlands in relation to sea-level behaviour. The model covers two general circumstances and is empirically supported by a range of field studies in the Holocene deposits of a number of British estuaries, particularly, the Severn. Where deposition was continuous over periods of centuries to millennia, and sea level fluctuated about a rising trend, the succession consists of repeated cycles of silt and peat lithofacies and biofacies in which series of transgressive overlaps (submergence sequences) alternate with series of regressive overlaps (emergence sequences) in association with the waxing and waning of tidal creek networks. Environmental and sea-level change are closely coupled, and equilibrium and secular pattern is of the kind represented ideally by a closed limit cycle. In the second circumstance, characteristic of unstable wetland shores and generally affecting smaller areas, coastal erosion ensures that episodes of deposition in the high intertidal zone last no more than a few centuries. The typical response is a series of regressive overlaps (emergence sequence) in erosively based high mudflat and salt-marsh silts that record, commonly as annual banding, exceptionally high deposition rates and a state of strong disequilibrium. Environmental change, including creek development, and sea-level movement are uncoupled. Only if deposition proceeds for a sufficiently long period, so that marshes mature, are equilibrium and close coupling regained. (C) 2002 Elsevier Science B.V. All rights reserved.

Bronze Age human ecodynamics in the Humber estuary

For much of lowland Britain during the Holocene one important factor in determining environmental change was sea level fluctuation. A net rise of circa 20 m, within an oscillating short term picture of transgression and regression, caused significant short to medium term challenges for people exploiting those resources. During transgression phases estuarine creek systems extended landwards, and during the final transgression phase, widespread sedimentation took place, allowing for the development of saltmarshes on tidal flats. In later prehistory the exploitation of lowlands and estuarine wetlands was predominantly for fishing, waterfowling and pastoral use, and this paper explores the human ecodynamics of the intertidal zone in the Humber estuary during the Bronze Age. Results of the Humber Wetlands Project's recent estuarine survey, will be used to argue that following a marine transgression circa 1500 cal BC, the foreshore was fully exploited in terms of food procurement. Furthermore the construction of hurdle trackways allowed access across expanding tidal creek systems to be maintained. This not only shows continued use of the most productive environments, and provides evidence for selective use of woodland, but also the continued exploitation of the intertidal zone may have played a role in the evolution of social and political structures in this area during the Bronze Age.

Early larval development in the laboratory of Alpheus estuariensis (Crustacea: Caridea) from the Amazon Region

O presente estudo descreve e ilustra em detalhes os quatro primeiros estágios de Alpheus estuariensis Christoffersen, 1984 a partir de larvas cultivadas em laboratório. Duas fêmeas ovígeras foram coletadas no canal de maré do estuário de Bragança, estado do Pará, nordeste do Brasil. Após a eclosão, as larvas foram colocadas em pequenos recipientes (com 10 larvas em cada). As fêmeas foram depositadas no Museu Paraense Emilio Goeldi (MPEG 0803) e as larvas de cada estágio larval no Museu zoológico da Universidade de São Paulo (MUSP18452). Foram dissecadas 10 larvas e exúvias com finas agulhas sob um microscópio ocular. Comparações morfológicas com outros estudos reportados sobre o desenvolvimento larval de espécies de Alpheus são brevemente discutidas.