The Flax Pond Ecosystem Study: Exchanges of CO"2 Between a Salt Marsh and the Atmosphere

Pb, Zn, and Mn, levels in sediment and common estuarine plants and animals colonizing dredge-spoil disposal areas were compared with levels occurring in the same materials from a natural salt-marsh. Finegrained dredge-spoil had considerabily higher levels of all three metals than did natural salt-marsh sediment, and large differences in the metals content of the spoil were observed, depending on sediment type.Pb levels in the Grass Shrimp (Palaemonetes pugio), Mummichog (Fundulus heteroclitus), Common Reed (Phragmites communis), Saltmarsh Cordgrass (Spartina alterniflora), and Saltmeadow Hay (Spartina patens), from dredge-spoil areas, were significantly higher at the 0.01 confidence level than in these species from the natural salt-marsh. Zn concentrations were significantly higher at this confidence level in the three plant species growing in dredge-spoil compared with those from the natural marsh. Mn content in Grass Shrimp from ponds in dredge-spoil disposal areas was significantly higher (0.05 confidence level) than in those from the natural marsh. Thus, dredge-spoil containing heavy metals, even though disposed of in specially designed diked containment areas, may act as a source of certain heavy metals that are potentially toxic to the biota.Data on the transfer of Pb and Mn in simple foodchains of the dredge-spoil pond ecosystem are presented and discussed in relation to feeding behaviour. Decreasing concentrations with increasing tropic level were observed for Pb and Mn, but no consistent pattern was noted with Zn.

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Urbanization impacts on production and recruitment of Fundulus heteroclitus in salt marsh creeks

Marine Ecology Progress Series ◽

10.3354/meps13378 ◽

2020 ◽

Vol 645 ◽

pp. 187-204

Author(s):

PJ Rudershausen ◽

JA Buckel

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Fundulus Heteroclitus ◽

Multiple Factor Analysis ◽

Southeastern Usa ◽

Density Dependent ◽

Dependent Relationship ◽

Juvenile Abundance ◽

The Relationship ◽

Throw Trap

It is unclear how urbanization affects secondary biological production in estuaries in the southeastern USA. We estimated production of larval/juvenile Fundulus heteroclitus in salt marsh areas of North Carolina tidal creeks and tested for factors influencing production. F. heteroclitus were collected with a throw trap in salt marshes of 5 creeks subjected to a range of urbanization intensities. Multiple factor analysis (MFA) was used to reduce dimensionality of habitat and urbanization effects in the creeks and their watersheds. Production was then related to the first 2 dimensions of the MFA, month, and year. Lastly, we determined the relationship between creek-wide larval/juvenile production and abundance from spring and abundance of adults from autumn of the same year. Production in marsh (g m-2 d-1) varied between years and was negatively related to the MFA dimension that indexed salt marsh; higher rates of production were related to creeks with higher percentages of marsh. An asymptotic relationship was found between abundance of adults and creek-wide production of larvae/juveniles and an even stronger density-dependent relationship was found between abundance of adults and creek-wide larval/juvenile abundance. Results demonstrate (1) the ability of F. heteroclitus to maintain production within salt marsh in creeks with a lesser percentage of marsh as long as this habitat is not removed altogether and (2) a density-dependent link between age-0 production/abundance and subsequent adult recruitment. Given the relationship between production and marsh area, natural resource agencies should consider impacts of development on production when permitting construction in the southeastern USA.

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