Tidal Marsh Ecology Research Papers (original) (raw)
Two tidal marshes in the New Jersey Meadowlands, one constructed and one natural were characterized to compare their ability to immobilize trace metals (Cd, Cr, Cu, Mn, Pb, and Zn). Surface and pore waters were sampled four times a year... more
Two tidal marshes in the New Jersey Meadowlands, one constructed and one natural were characterized to compare their ability to immobilize trace metals (Cd, Cr, Cu, Mn, Pb, and Zn). Surface and pore waters were sampled four times a year between 2008 and 2010 and sediment cores were collected yearly in the constructed marsh and once in 2010 in the natural marsh. Interactions of trace metals with redox active species such as iron and sulfide as well as with organic matter were investigated. Precipitation with sulfides played a major role in immobilizing certain trace metals, including Cr, Mn, and Pb. At both sites, the presence of sulfide did not preclude the presence of dissolved trace metals in pore-water at concentrations exceeding their metal sulfide solubility product. Thermodynamic equilibrium modeling indicated these dissolved metals remained in solution due to an association with heterogeneous dissolved organic carbon. No net trace metal accumulation in the surficial sediments of the constructed marsh was noted between 2007 and 2010. This implied that a dynamic equilibrium of trace metal flux into and out of the sediments was established, rather than a long-term net accumulation of trace metals. In the constructed marsh, little difference was found between the immobilization potential in the area of intermittent flooding (high marsh) and the area of sustained flooding (low marsh). The newly constructed wetland immobilized significantly more Cr, Mn, and Zn than the natural marsh and similar concentrations of Cd, Cu, and Pb. This may be due to increased redox buffering through a larger FeS buffering pool against tidally induced oxygen delivery.
Barrier-islands are common landforms and biodiverse habitats, yet they received scarce neoichnological attention. This gap is tackled by studying the Mula di Muggia barrier-island system (Grado lagoon, Italy), focus-ing on morphology,... more
Barrier-islands are common landforms and biodiverse habitats, yet they received scarce neoichnological attention. This gap is tackled by studying the Mula di Muggia barrier-island system (Grado lagoon, Italy), focus-ing on morphology, ecology and ethology of individual traces. The following incipient ichnotaxa are Thalassinoides and 'squat burrows'. Vertebrate (Avipeda-/Ardeipeda-like, Canipeda) and invertebrate tracks ('parallel furrows') are also described. For each ichnotaxon, tracemaker and behavior are discussed, together with their position with respect to sediment barriers. Results suggest that sediment barriers impose a sharp contrast in terms of ichnological composition. Back-barrier is dominated by branched burrows (i.e. Thalassinoides, Parmaichnus), while the fore-barrier presents vertical and U-shaped burrows (Arenicolites, Skolithos). The environmental conditions of the back-barrier show that low-oxygen substrates favor intense bioturbation, provided that the water column is sufficiently oxygenated.
Habitat functions of a constructed tidal marsh and two adjacent natural tidal marshes were compared between marshes and with similar data collected in the same marshes 7 years earlier. The marshes were sampled for fish, blue crabs,... more
Habitat functions of a constructed tidal marsh and two adjacent natural tidal marshes were compared between marshes and with similar data collected in the same marshes 7 years earlier. The marshes were sampled for fish, blue crabs, benthic infauna, vegetation community type, stem density and cover, salinity, temperature, dissolved oxygen, organic carbon, and bird utilization. The constructed marsh has progressed to a general level of function similar to that of nearby natural marshes. Some morphological differences remain, such as the differences in community type ratios. Significant differences in habitat function remain in three areas: sediment organic carbon at depth, mature saltbush density, and bird utilization (related to saltbush density). The addition of organic soil amendments and mature saltbush in the construction of tidal marshes will help in the progression of constructed marshes to functional equivalency with natural marshes. Specific functions can be enhanced for fish utilization (more subtidal habitat) and for birds (more shrub habitat) depending on management priorities.
As human development continues in coastal areas, shoreline properties adjacent to expansive tidal marsh habitat are increasingly used for access to coastal waterways via long piers (.30 m) over marsh habitat. These tidal wetlands provide... more
As human development continues in coastal areas, shoreline properties adjacent to expansive tidal marsh habitat are increasingly used for access to coastal waterways via long piers (.30 m) over marsh habitat. These tidal wetlands provide breeding and foraging habitat for many marsh birds, which may be affected by the human disturbance associated with long piers. Our objectives were to determine the effect of long piers over vegetated tidal marshes on the relative abundance and species richness of marsh birds. We completed combined passive and callback surveys in tidal marsh habitat at 22 sites with long piers and 24 sites without long piers, May-July 2005-2006 in Worcester County, Maryland, USA. Pier sites had lower relative abundance and species richness of obligate marsh birds than nonpier sites. Pier sites had a greater relative abundance of gulls, terns, herons, and egrets than nonpier sites. Pier sites had fewer species of herons and egrets than at nonpier sites. The presence of long piers had no affect on facultative marsh birds. Long pier density was negatively related to obligate marsh bird relative abundance and species richness, and facultative marsh bird species richness, whereas it was positively related to the relative abundance and species richness of gulls and terns. Herons and egrets relative abundance and species richness were not related to long pier density. Obligate marsh birds were negatively affected by long piers, whereas herons, egrets, gulls, and terns appeared to benefit from perching opportunities. Based on the negative effects of long piers on obligate marsh birds, management should focus on reducing the presence and density of long piers in tidal marshes by requiring the removal of existing long piers, or reducing or eliminating permits for construction of new long piers.
Understanding the characteristics of high-quality avian habitat is critical for guiding salt marsh management and restoration. Existing insights into salt marsh avian habitat are often based on the composition of marsh vegetation, e.g.,... more
Understanding the characteristics of high-quality avian habitat is critical for guiding salt marsh management and restoration. Existing insights into salt marsh avian habitat are often based on the composition of marsh vegetation, e.g., individual plant species cover. This study investigated whether the spatial configuration of marsh surface cover (e.g., patch number, density, size, shape complexity and compactness, degree of dissection of the landscape, variation and repetition of cover type, and the variance within these metrics) is a useful, additional indicator of avian habitat quality for the Alameda Song Sparrow (Melospiza melodia pusillula), a non-migratory California Species of Special Concern endemic to southern San Francisco Bay. M. m. pusillula density during the breeding seasons of 2002 through 2005 was estimated at 82 observation points in 10 marsh sites within the bird's geographic range. The mean bird density index (overall mean: 5.61 birds detected per hectare of marsh) was not significantly different among marshes of different ages. We mapped the vegetation zones, open water, and upland areas within each marsh site using high resolution aerial photographs and automated classification analysis. We quantified the configuration of surface cover around each bird observation point by 31 metrics. Bird density index was best modeled by a multiple linear regression containing positive relationships with the metrics Mean Core Area Index and Patch Core Area Coefficient of Variation (R 2 = 0.210, p < 0.0001). Qualitatively, this model suggested that M. m. pusillula abundance during the breeding season was greatest in marsh areas with compact patches that spanned a variety of patch sizes from moderate-tolarge, uninterrupted by other cover. We conclude that configuration-based vegetation pattern analysis could usefully complement more customary compositionbased habitat assessments to aid wetland habitat research, management, and restoration.
Kleptoparasitism involves the theft of resources such as food items from one individual by another. Such food-stealing behaviour can have important consequences for birds, in terms of individual fitness and population sizes. In order to... more
Kleptoparasitism involves the theft of resources such as food items from one individual by another. Such food-stealing behaviour can have important consequences for birds, in terms of individual fitness and population sizes. In order to understand avian host-kleptoparasite interactions, studies are needed which identify the factors which modulate the risk of kleptoparasitism. In temperate European intertidal areas, Eurasian oystercatchers (Haematopus ostralegus) feed primarily on bivalve molluscs, which may be stolen by kleptoparasitic species such as carrion crows (Corvus corone) and herring gulls (Larus argentatus). In this study we combined overwinter foraging observations of oystercatchers and their kleptoparasites on the Exe Estuary, UK, with statistical modelling to identify the factors that influence the likelihood of successful food stealing behaviour occurring. Across the winter, 16.4 % of oystercatcher foraging attempts ended in successful kleptoparasitism; the risk of theft was lowest in February (10.8 %) and highest in December (36.3 %). Using an information theoretic approach to compare multiple logistic regression models we present evidence that the outcome of host foraging attempts varied with the number of kleptoparasites per host within the foraging patch for two out of five individual months, and for all months grouped. Successful, kleptoparasitism was more likely to occur when the total number of all kleptoparasites per host was greater. Across the entire winter study period, oystercatcher foraging attempts that resulted in kleptoparasitism were associated with a mean number of kleptoparasites per host that was more than double that for foraging attempts that ended in the oystercatcher successfully consuming the mussel. Conversely, the stage of the tidal cycle within the estuary did not affect the outcome of oystercatcher foraging attempts. Our study provides evidence that bird numbers influence the risk of kleptoparasitism within avian assemblages.