Recovery of benthic nematode assemblages after a major collapse of Zostera noltii seagrass beds.

Abstract

During 2008, Zostera noltii seagrass beds of the Mira estuary (SW coast of Portugal) suffered a total collapse, though during 2009 slight symptoms of their recovery were already observed. This association of events, in a short period of time, creates a rare opportunity for obtaining new knowledge concerning natural recovery of ecosystems and habitats. The principal goal is to analyse nematode community responses to the collapse of seagrass beds. Through a comparison of pre- and post-impact data, nematode assemblage recovery and resilience will be assessed. Additionally, the carbon resources utilized by nematodes will be examined, in order to better understand the importance of seagrass detritus as a potential resource for meiobenthic organisms. Significant differences were observed in the community patterns and trophic composition of nematode assemblages before and after the Zostera collapse. The dominant genera of the precollapse community were Terschellingia, Odontophora and Linhomoeus, generally considered microbivorous and/or deposit-feeding nematodes. Immediately after the collapse, they were replaced by Ptycholaimus, Paracomesoma and Metachromodora, all of which are herbivores feeding on diatoms and other microalgae.