Use of Artificial Eelgrass Mats by Saltmarsh-Nesting Common Terns (Sterna hirundo)

Terns and skimmers nesting on saltmarsh islands often suffer large nest losses due to tidal and storm flooding. Nests located near the center of an island and on wrack (mats of dead vegetation, mostly eelgrass Zostera) are less susceptible to flooding than those near the edge of an island and those on bare soil or in saltmarsh cordgrass (Spartina alterniflora). In the 1980’s Burger and Gochfeld constructed artificial eelgrass mats on saltmarsh islands in Ocean County, New Jersey. These mats were used as nesting substrate by common terns (Sterna hirundo) and black skimmers (Rynchops niger). Every year since 2002 I have transported eelgrass to one of their original sites to make artificial mats. This site, Pettit Island, typically supports between 125 and 200 pairs of common terns. There has often been very little natural wrack present on the island at the start of the breeding season, and in most years natural wrack has been most common along the edges of the island. The terns readily used the artificial mats for nesting substrate. Because I placed artificial mats in the center of the island, the terns have often avoided the large nest losses incurred by terns nesting in peripheral locations. However, during particularly severe flooding events even centrally located nests on mats are vulnerable. Construction of eelgrass mats represents an easy habitat manipulation that can improve the nesting success of marsh-nesting seabirds.

Mersey Estuary saltmarsh vegetation survey 2002

This is the Mersey Estuary Saltmarsh vegetation survey 2002 report produced by the English Nature Cheshire in 2003. This report looks at the mapping of vegetation communities on the saltmarsh of the Mersey Estuary. The total area of saltmarsh and associated communities within the Mersey Estuary was found to be 724.1 ha. Most of the saltmarsh in the Mersey Estuary is presently ungrazed or only very lightly grazed, creating a very rank sward in excess of 20 cm in height which is not generally suitable for grazing or roosting birds. On the northern side of the Mersey Estuary, the saltmarsh around the Hale Decoy was lightly grazed by horses, but the remainder was ungrazed. On the south side, the saltmarsh was fairly heavily sheep-grazed along the Frodsham Score, very lightly grazed at Ince Banks by sheep straying from Frodsham and ungrazed at Stanlow Banks. Despite much of it presently being ungrazed, the saltmarsh of the Mersey Estuary is relatively poor in plant species. It appears that this is because the ungrazed areas have been so for less than 20 years and have thus not had time to develop the diversity of a long-established ungrazed marsh. However, withdrawal or depletion of grazing has produced a rank sward which is less valuable to grazing and roosting birds.

Understanding 2H/1H systematics of leaf wax n-alkanes in coastal plants at Stiffkey saltmarsh, Norfolk, UK

Interpretation of sedimentary n-alkyl lipid d2H data is complicated by a limited understanding of factors controlling interspecies variation in biomarker 2H/1H composition. To distinguish between the effects of interrelated environmental, physical and biochemical controls on the hydrogen isotope composition of n-alkyl lipids, we conducted linked d2H analyses of soil water, xylem water, leaf water and n-alkanes from a range of C3 and C4 plants growing at a UK saltmarsh (i) across multiple sampling sites, (ii) throughout the 2012 growing season, and (iii) at different times of the day. Soil waters varied isotopically by up to 35& depending on marsh sub-environment, and exhibited site-specific seasonal shifts in d2H up to a maximum of 31 per mil. Maximum interspecies variation in xylem water was 38 per mil, while leaf waters differed seasonally by a maximum of 29 per mil. Leaf wax n-alkane 2H/1H, however, consistently varied by over 100 per mil throughout the 2012 growing season, resulting in an interspecies range in the ewax/leaf water values of -79 per mil to –227 per mil. From the discrepancy in the magnitude of these isotopic differences, we conclude that mechanisms driving variation in the 2H/1H composition of leaf water, including (i) spatial changes in soil water 2H/1H, (ii) temporal changes in soil water 2H/1H, (iii) differences in xylem water 2H/1H, and (iv) differences in leaf water evaporative 2H-enrichment due to varied plant life forms, cannot explain the range of n-alkane d2H values we observed. Results from this study suggests that accurate reconstructions of palaeoclimate regimes from sedimentary n-alkane d2H require further research to constrain those biological mechanisms influencing species-specific differences in 2H/1H fractionation during lipid biosynthesis, in particular where plants have developed biochemical adaptations to water-stressed conditions. Understanding how these mechanisms interact with environmental conditions will be crucial to ensure accurate interpretation of hydrogen isotope signals from the geological record.

Impact of saltmarsh disturbance on seed quality of Sarcocornia (Sarcocornia quinqueflora), a food plant of an endangered Australian parrot

The article presents a study which evaluates the impact of saltmarsh perturbation on seed quality of Sarcocornia which is a food for the endangered Orange-bellied parrot in Australia. It notes the significant impact of grazing on the energy and availability of Sarcocornia seeds in saltmarshes and indicates that graze-free saltmarshes with regular inundation provide the highest potential for Sarcocornia seed availability. Further, the substantial factor of soil characteristics and salinity of flood water and inundation on the seed production of Sarcocornia is also discussed.

Ecology and control of the southern saltmarsh mosquito, Ochlerotatus Camptorhynchus(Thomson), in Victoria

This study has revealed important ecological attributes of the southern saltmarsh mosquito in Victoria, resulting in an increased understanding of population peaks and their relation to Ross River virus disease and meteorological factors. Together with new information on its larval development, these results have further increased options for its control by local governments and public health authorities.