Biodiversity organization and implication of nutrient inputs in aquatic systems
Author(s)
Careddu, Giulio
Date Issued
June 17, 2016
Type
Doctoral Thesis
Abstract
Since the industrial revolution human activities, implemented on large scale by climate change,
global warming and ocean acidification, have severely altered the global environment, resulting
in a massive loss of biodiversity and alteration of ecosystems and their functions such as nutrient
cycling, primary production, decomposition, pollination, pest control, resistance to invasion.
Against this background the most important goal of environmental management is to preserve or
recover the biodiversity and its function at ecosystem level. Define scenarios related to the
impact of climate change on the life in marine ecosystems and its recovery is an essential step to
plan adaptation strategies but requires mechanistic knowledge, that are currently lacking, about
the relationship between the biodiversity organization and the anthropogenic disturbance
components. This work describes trophic relationships, organic matter pathways and biodiversity
organization in aquatic systems subject to different natural or anthropogenic pressures. Stable
isotopes analysis of biota and nutrient pools of aquatic systems (marine coastal area, river,
coastal lakes and high-Artic lakes), in conjunction with other ancillary analyses, were used to:
detect autochthonous/allochthonous nutrient inputs, trace anthropogenic nitrogen inputs,
elucidate trophic interactions among organisms and trophic niche organization also at single
specie level. The results of these researches try to close a gap existing between the ecosystem
ecology and the community ecology linking the analysis of nutrient fluxes and trophic pathways
to food web and niche theory. SIA was a useful technique in tracing the origin and fate of
nutrient pollutant inputs and in aquatic ecosystems. Coupled with changes in basal resource
inputs, we observed changing in food web topology across the systems investigated, changes that
are in accordance with OFT an MTE. The description of changes in species’ trophic traits and
food web organisation at the local scale could provide useful information on the role of
biodiversity organisation in propagating or attenuating disturbance, information that cannot be
obtained with reference to species occurrence and abundance alone. Furthermore, knowledge of
the trophic linkages could be crucial to defending aquatic ecosystems from potential
anthropogenic pollutants and to identify those species that are most subject to accumulation.
Additional information
Dottorato di ricerca in Ecologia e gestione delle risorse biologiche