Eutrophication indicators in the Hutt River Estuary, New Zealand

The Hutt River estuary near Wellington New Zealand has a luxuriant intertidal band of green macroalgae growing throughout the year. Investigations of water chemistry suggested that the upstream freshwater river was likely P-limited and passed on watershed nitrogen nutrients to the estuary. P fertilisation of the estuary from marine waters led to crossing N and P nutrient loadings that support the observed macroalgal proliferation. Chemical analyses of nutrients, macroalgae, and barnacle and mussel consumers were used to understand further the mix of factors controlling eutrophication and food webs in this urban estuary. delta N-15 and delta C-13 were respective helpful indicators of watershed N inputs and C cycling between benthic and pelagic parts of the food web.