South Milton Ley is a small coastal wetland in Southern England. A sand-bar forms periodically at its seaward end and separates fresh water from the sea. The common reed Phragmites australis dominates the wetland and when a sand bar is present a shallow freshwater lake forms. Monthly water budgets were prepared for the years 1994, 1995 and 1996 and intermittent flooding of the Ley was also monitored. This information was used to calculate a range of residence times (between one hour and eleven days) and the characteristics of various flow regimes when the sandbar, which dams the Ley, is open or closed. Reed growth and the lake's ecology are potentially influenced by effluent from a sewage treatment works (STW) that discharges into the wetland. Water chemistry and hydrology of the wetland have been studied alongside experiments to investigate any effects of nutrient enrichment from the STW on reed growth. Inflowing and outflowing waters were analysed in order to determine concentrations of total oxidised nitrogen (TON), total dissolved nitrogen (TDN), soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP) and potassium (K). Over the study period the annual load of SRP to the Ley increased from 3.65 gmˉ² aˉ¹ in 1992 to 8.1 gmˉ² aˉ¹ in 1996. TON load rose from 69.35 g mˉ² aˉ¹ in 1992 to 104.8 g mˉ² aˉ¹ in 1996. K fell from 97.3 g mˉ² aˉ¹ in 1994 to 96.4 g mˉ² aˉ¹ in 1996. The STW uses a Reedbed Treatment System (RBTS) to 'polish' its final effluent. The efficiency o f the RBTS was studied and during 1996 the efficiency rate for T ON was 20.9% and for SRP was 9.3%. Measurements of height, diameter, numbers of internodes, density and biomass of reeds collected from South Milton Ley were undertaken during August 1994 and 1995. Results of analyses for 1994 indicate that reeds were thinner and possessed fewer seedheads than those of 1995 but that density was greater. Reed fieldwork during 1994 found that height, diameter, numbers of internodes, biomass and number of seedheads were greater below the STW than above. During 1995 only seedhead production was greater below the outlet. The wettest area of the Ley contained reeds with greatest height and diameter. The driest area produced a higher density of reed growth. Laboratory experiments suggested that low N:K ratios and high P:K produced taller plants. Data from reed fieldwork together with results from hydrology and water chemistry studies were used in a statistical analysis in order to determine which, if any of these factors caused changes in reed growth. A conclusive link between water chemistry, hydrology and plant variables was not found. Correlation analysis for 1994 indicated that high concentrations of SRP and TON could produce thin reeds with low biomass. Analysis for 1995 suggested that elevated K values could produce a high density of short reeds. Water depth was found to have a significant effect (P < 0.001) on diameter. The key factors for reed decline (high water levels from spring to winter which can inhibit reed regeneration and increase residence times, increasing nutrient loads and changes in the ratio of N:P:K which could alter reed growth) are all present. At its present loading the Ley is nutrient rich and does not appear to be buffering wetland waters. After data analysis and fieldwork was completed a bloom of Oscillatoria sp.occurred at the seaward end of the Ley during August 1999. This, the first know occurrence of a bloom may be an indication that changes in the ecosystem of South Milton Ley are occurring. For the future, a programme of nutrient reduction, hydrological management and growing knowledge of wetland processes may prevent adverse changes.

The overall objective of this study was to provide a spatial pattern analysis offish distribution in the Great Lakes and to relate these patterns to shoreline features such as coastal wetlands, tributaries and substrate type. Very little is known regarding the distribution patterns of fish in the Great Lakes at the geographical scale of each lake basin. I first explored whether there were systematic patterns in distribution offish and coastal wetlands by looking at density maps of each and calculating nearest neighbor distances. I used three different classification schemes to sort the 139 fish taxa into functional categories to produce ecologically meaningful distribution maps. There were striking differences in the overall distribution pattern of nursery and spawning habitat in the five Great Lakes when data were compared for Jude and Pappas' classification taxocenes: open-water, intermediate and coastal. Overall, open-water species were the most abundant, and were also widely distributed throughout all five lakes. Coastal species were the least abundant and appeared to be restricted to the two lower lakes. The distribution pattern of coastal and intermediate taxa overlapped a great deal; both taxocenes made extensive use of the two lower lakes for spawning and nursery habitat during this synoptic survey, especially in western Lake Erie and eastern Lake Ontario. Fish distribution patterns sorted by thermal preference and by reproductive guild were compared with those sorted by taxocene. Results from a chi-square analysis indicated a high degree of overlap between thermal classes and taxocenes. There were also positive associations between many reproductive guilds and the three taxocenes, although these were not as strong as the previous comparison. I then examined spatial association between distributions of fish and coastal wetlands and other geomorphic features by testing the distribution offish along the shore of the Great Lakes and calculating the correlation between fish and coastal wetlands of Lake Ontario. A chi-square goodness-of-fit test indicated strong associations between the distribution offish and three shoreline classes: (wetland, sandy beach/dunes and bluff) and fish used coast~cl wetlands preferentially for spawning and nursery habitat at a basin-wide scale. Bivariate pattern analysis indicated that occurrences offish in L. Ontario were positively associated with both coastal wetlands and tributaries, although the relationship was considerably weaker for tributaries than for wetlands. Results from this study indicated that 1) Fish have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 2) Coastal wetlands have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 3) Spatial distribution offish and wetlands is positively associated; 4) The preferred utilization of coastal wetlands by majority of the Great Lakes fishes is consistent across geographic scales, from the site level to that of the entire Great Lakes basin. / Thesis / Master of Science (MSc)

archives@tulane.edu / Over the past two centuries, coastal wetlands have become increasingly threatened by accelerated relative sea-level rise and anthropogenic modification. Engineered structures such as sea walls, levees, and drainage systems prevent natural processes of sediment distribution, reducing the resilience of coastal ecosystems. Land subsidence and shoreline erosion combine with global sea-level rise to make low-elevation coastal zones increasingly vulnerable to submergence. This dissertation examines processes of sediment accumulation, compaction, and relative sea-level rise in coastal wetlands and assesses strategies for restoration. I find that organic content strongly controls sediment compaction in wetland sediments. At least 80% of compaction happens quickly, largely within the first 100 years after deposition and in the top 1 m of the subsurface. This rapid shallow compaction is generally not recorded by traditional methods of measuring relative sea-level rise in low-elevation coastal zones (i.e., tide gauges and global navigation satellite systems). As a result, tide gauges generally underestimate rates of relative sea-level rise in low-elevation coastal zones and these areas may be at a greater risk of flooding than previously realized. However, despite accelerated rates of relative sea-level rise and rapid sediment compaction, coastal restoration efforts such as river diversions can be successful in building new land in some areas. I find that sediment deposition responds non-linearly to water discharge, reaching a maximum at moderate discharge. Wetlands are more likely to keep up with relative sea-level rise if hydrodynamic conditions are optimized to retain mineral sediment in targeted restoration areas. / 1 / Margaret Keogh

No description available.

Coastal wetlands of Georgian Bay have been virtually ignored by ecologists until recently, when these ecosystems were found to have exceptionally high biodiversity compared to other Gr,~at Lakes wetlands. To address this deficiency, we conducted a baseline survey (2002 to 2007) to determine the biotic and abiotic characteristics of 92 wetlands in 18 quatemary watersheds, using a suite of published ecological indices developed specifically for coastal wetlands (Water Quality Index (WQI); adjusted Wetland Macrophyte Index (WMiadj), and the Wetland Fish IndexBasinPAex (WFIBasinPAex)). Although a majority of the watersheds are located in remote eastern and northern parts of the Bay and therefore receive minimal human disturbance, one watershed, Sturgeon River, located in southern Georgian Bay receives relatively high urban, recreational and agricultural disturbance. Mean scores of WQI and WMiadj varied significantly across the watersheds, ranging from 0.48 to 2.15, and from 2.29 to 3.77, respectively. Mean WFIBasinPAex scores, however, were less variable and only ranged from 3.53 to 3.86. Of the 88 macrophyte species identified, the most common were hardstem bulrush. (Schoenoplectus acutus), water celery (Vallisneria americana), richardson's pondweed (Potamogeton richardsonii), slender waternymph (Najasjlexilis) and Canadian waterweed (Elodea canadensis). Six non-native macrophytes, Purple loosestrife (Lythrum wlicaria), narrow-leaf cattail (Typha angustifolia), hybrid cattail (Typha x glauca), Eurasian milfoil (Myriophyllum spicatum), curly pondweed (Potamogeton crispw) and frogbit (Hydrocharus morsus-ranae) were also recorded, the most common ofwhieh was Eurasian milfoil. Sago pondweed (Stuckenia pectinata), a native species that can be invasive, and is tolerant of poor water-quality, was present in about half of the watersheds. Ofthe 51 fish species, pumpkinseed (Lepomis gibbosus) bluntnose minnow (Pfmephales notatus), brown bullhead (Ameiurus nebulosus), rock bass (Ambloplites rupestris), and yellow perch (Percajlavescens) were the most widespread and abundant. Three non-native species, common carp (Cyprinus carpio), alewife (Alosa pesudoharengus), and round goby (Neogobius melanostomus) were present but not dominant. WMI scores were highly correlated with WQI scores, and as expected, wetlands in the most disturbed southern watershed were associated with the lowest WQI and WM[ scores, and had the greatest number of exotic species. However, WMI scores of wetlands in a few exposed sites located at the tip of the Bruce Peninsula were similarly low, even though these sites are not yet impacted by human activities. There was no significant relationship between WFIBasinPAand WQI scores, although the WFIBasin PA did not seem to be affected by exposure. We recommend that the WQI and WMiadj be used in long-term monitoring programs of Georgian Bay to track negative impacts of human disturbance on these valuable ecosystems. / Thesis / Master of Science (MS)

GENERAL ABSTRACT The Laurentian Great Lake wetlands are highly productive and complex systems. The net loss of wetlands since European settlement has been dramatic. The remaining coastal wetlands continue to be threatened with obliteration or severe environmental degradation. Therefore, the overall objective of this study was to provide information on the ecology of the remaining coastal wetlands within the lower Great Lakes. This study describes a coastal wetland fish community along the north shore of Lake Erie within Long Point Marsh complex over a 24-h period and catch characteristics of three common fishing techniques. The fish community was sampled at two hour intervals over a 24-h period in June, and used three types of gear to determine possible sampling biases from the different collection techniques. A total of 497 fish encompassing 11 taxa were collected. A 2-h interval, four hours prior to sunset, netted the largest number of taxa (including 3 functional feeding groups: ornmvores, planktivores, and piscivores ), as well as highest abundance and biomass values. Seine netting demonstrated a biased towards sampling the smaller planktivores, while fyke nets were biased towards larger omnivorous fish, and boat electrofishing was biased towards the large piscivores. These results will assist scientists and lake managers to develop standardized fish sampling protocol in order to accurately assess differences in wetland fish communities. Seven coastal wetlands within Lake Erie and Ontario along both the Canadian and United States shorelines were studied to verify predicted relationships from the literature and determine the relative influences of various habitat features on zooplankton community structure. Water quality, aquatic macrophyte, zooplankton, and fish community information were collected from the wetlands between July 4th and August 2nd of 2001. The predicted relationships from the literature concerning water quality and macrophyte species richness were verified by the results of this work. Water quality and macrophyte species richness were the most accurate predictors of wetland zooplankton community structure. Identifying the wetland characteristics that play primary roles in structuring zooplankton communities will also assist lake managers to make informed decisions of how to most effectively improve zooplankton habitat, to foster larger-bodied zooplankton populations, making the habitat more suitable for larger populations of larval and juvenile fish. / Thesis / Master of Science (MS)

Taiwan is an island surrounded by sea. Due to the topography, the coastal wetlands distribute almost around the west seashore, and some at the estuary of the east seashore. The coastal wetland is a transitional area between territory ecosystem and marine ecosystem. The environment of the coastal wetland is influenced by tide and season, thus the distribution of vegetations here exhibits a dynamic equilibrium. This study attempts to investigate the distribution and composition of the vegetation and the appearance of the habitat environment at the coastal wetland of Taiwan. According to the results, 173 species belonging to 50 families have been recorded. This indicates that the diversity of the marsh vegetation at the coastal wetland is low. Most of the species belong to Gramineae, Compositae and Cyperaceae. Paspalum vaginatum and Phragmites karka are the most dominant plant at coastal marsh environments. According to the results of detrended correspondence analysis (DCA) and cluster analysis (CA), 16 vegetation types including one subtype and one transitional type are classified. The habitats of these vegetation types can be classified into five types, namely tidal fresh water marsh, fresh water-salt marsh, wet meadow, salt marsh and submerged environment. Most of these vegetation types have only one major dominant species. The distribution of the marsh vegetation features a belting pattern, which is mainly limited by the maximum of their salt tolerance from coastal toward inland, or estuary toward headwaters. Subsequently, it can by influenced by soil moisture and pH value. Furthermore, the vegetations are influenced by many additional environmental factors, resulting in a mosaic distribution of vegetation types. The marsh vegetation is processing at an unstable and developing period. Because the coastal wetland is seriously disturbed by human activities, the environmental variation becomes greater. Therefore, the transitional vegetations were observed frequently. Finally, the development pressure due to economic demand is the major cause that makes coastal wetland disappeared. It is urgently needed to protect this sensitive natural resource.

Microbial mats have played an important role in the carbon (C) and nutrient cycles since the Archean Eon and modern mats are important contributors to the biogeochemistry of intertidal wetlands. Microbial mats are flat assemblages of microbes that are currently found in many unvegetated habitats globally. Intertidal salt pans are a common habitat for microbial mats, however little is known about the distribution of microbial mats within the intertidal landscape. Understanding the spatial distribution of microbial mats is critical to developing quantitative estimates of the impacts of microbial mats on their ecosystems. We photographically measured the presence and density of microbial mats within 1 m2 quadrats across a landscape scale (~1000 Ha) on the Gulf Coast of Florida. The wide variety of metabolic processes that are found within microbial mats makes the net biogeochemical impacts of the microbial mats highly variable as well. To explore the biogeochemistry associated with microbial mats, we measured a suite of soil attributes under microbial mats and compared those measurements to nearby soils without microbial mats. We found that microbial mats are found on soils with biogeochemical attributes that are significantly different than soils without microbial mats. Soil organic matter, nitrate concentration, and soil temperature significantly increased in soils under microbial mats; pH was significantly lower in soils under microbial mats. Also notable was although the concentration of soil organic matter was higher, the bioavailability of that organic matter was significantly lower. Microbial mat presence is correlated with geomorphic variables such as proximal boundaries, as well as neighboring vegetation and other microbial mats.

Louisiana’s coastal wetlands support millions of resident and migratory birds annually but account for 80% of the nation’s coastal wetland loss. Marsh terracing is a restoration technique that constructs segmented ridges in open water areas to enhance marsh conditions. Despite widespread use, their value as avian habitat has received limited study. Using ground and aerial surveys, we evaluated avian use of marsh terraces across 24 paired sites (marsh terrace and non-terrace sites) in coastal Louisiana. Avian surveys focused on breeding secretive marsh birds (SMB) and wintering waterfowl. Results indicate that presence or absence of marsh terraces influenced numbers of ducks detected, though relative abundance varied spatially and temporally. The effect on SMB abundance varied by species and environmental variables, including habitat structure and water availability. The study highlights the complexity of bird responses to marsh terracing, emphasizing the importance of considering species-specific habitat preferences and environmental factors in restoration planning.

Phragmites australis is a perennial grass presently invading many intertidal and freshwater wetlands throughout much of the Atlantic Coast of North America. The spread of Phragmites into coastal wetlands is in part determined by available freshwater and nutrients, especially nitrogen, within the watershed where Phragmites populations occur. The Eastern Shore of Virginia is an intensive agricultural area, and watershed landcover may play a major role in Phragmites invasion. Forty-five Phragmites patches were sampled in eight VA Eastern Shore mainland watersheds and on a barrier island. Regardless of watershed landcover characteristics, there was little variation in Phragmites australis patch characteristics along the oceanside of the entire Eastern Shore of Virginia. Phragmites is a generalist with broad environmental tolerances. Thus, successful management and eradication plans may have broad scale application for this invasive grass.