seabirds

Biotic connectivity between ecosystems can provide major transport of organic matter and nutrients, influencing ecosystem structure and productivity, yet the implications are poorly understood owing to human disruptions of natural flows. When abundant, seabirds feeding in the open ocean transport large quantities of nutrients onto islands, enhancing the productivity of island fauna and flora. Whether leaching of these nutrients back into the sea influences the productivity, structure and functioning of adjacent coral reef ecosystems is not known.

Islands house a majority of the world’s biodiversity and are thus critical for biodiversity conservation. Seabird nesting colonies provide nutrients that are integral to maintain island biodiversity and ecosystem function. Invasive rats destroy seabird colonies and thus the island ecosystems that depend on seabird-derived nutrients. After rat eradication, it is unclear how long ecosystem recovery may take, although some speculate on the order of centuries. I looked at ecosystem recovery along a chronosequence of islands that had 12–22 years to recover following rat eradication.

Introduced rats (Rattus spp.) can affect island vegetation structure and ecosystem functioning, both directly and indirectly (through the reduction of seabird populations). The extent to which structure and function of islands where rats have been eradicated will converge on uninvaded islands remains unclear. We compared three groups of islands in New Zealand: islands never invaded by rats, islands with rats, and islands on which rats have been controlled. Differences between island groups in soil and leaf chemistry and leaf production were largely explained by burrow densities.