| Abstract |
The current study examined the direct interactions between intertidal seagrasses (Zosteraceae) and burrowing ghost shrimps
(Callianassidae) and their influence on associated infaunal assemblages. Reciprocal transplant experiments conducted in two
temperate regions revealed different interactions between both types of organism. In the U.S.A., seagrass prospered in all
treatments, irrespective of the presence of ghost shrimp, whilst ghost shrimp declined in plots containing seagrass. In New Zealand,
neither transplanted ghost shrimp nor seagrass became established in experimental plots, at the same time, neither type of organism
appeared to be affected by the experimental addition of transplants. The differences in interactions between seagrass and ghost
shrimp appeared to be related to seasonal differences in the timing of the transplant experiments and the pairing of particular ghost
shrimp and seagrass species in each region. Infaunal assemblages showed distinct differences between seagrass and ghost shrimp
treatments and reflected the dominant type of organism present. In treatments where transplanted seagrass or ghost shrimp became
established, assemblage composition shifted in accordance with the type of transplanted organism. Differences in assemblage
composition were characterised by higher relative abundances of discriminating taxa in treatments dominated by seagrass. The
overall patterns of infaunal assemblage composition were correlated with a number of variables including the number of shoots,
above-, below-ground seagrass biomass, % fines/sand, % total organic carbon, and sediment chlorophyll a. Findings from this
study highlight the functional importance of intertidal seagrasses and burrowing ghost shrimps and reveal some of the ecological
repercussions associated with changes in the distribution of these sympatric ecosystem engineers. |
