A trait-based perspective on seagrass ecology: from plant to ecosystem level processes

Seagrasses are marine flowering plants that inhabit the coastal area forming important ecosystems due to a number of ecosystem services they provide. However, they are subjected to both global and local impacts, including warming water temperatures and eutrophication, which threaten their survival. Despite the fact that the most diverse seagrass meadows are found in the tropical Indo-Pacific Region, there is less information about tropical species than their temperate counterparts. There are, therefore, knowledge gaps in the response of tropical seagrass meadows to environmental drivers and their links to ecosystem functions and services. In the last three decades, trait-based frameworks (TBFs) have advanced different fields of ecological research establishing novel links between functional traits, environmental drivers and ecosystem functions.

However, the use of TBFs in seagrass research is currently in its infancy. The goal of this dissertation is the incorporation of TBFs into seagrass ecological research, assessing the importance of traits at different organizational levels, from their individual responses to environmental drivers, to the effect of traits on the interspecific competition of seagrass species and, lastly, their effect on ecosystem functioning. The study site chosen for this work was Unguja Island (Zanzibar Archipelago, Tanzania).

Knowledge gaps in seagrass trait research were identified through a systematic literature review, showing that only 7% of the studies used a TBF. The responses of traits of individual seagrass plants of tropical species (Halophila stipulacea, Cymodocea serrulata, Thalassia hemprichii and Enhalus acoroides) were assessed to two environmental drivers: temperature (global) and nutrient enrichment (local). The results of this experiment showed that trait responses are species-specific, and that temperature was a much more significant driver than nutrient enrichment. Seagrass traits linked to light and nutrient competition affected space preemption among seagrass species. The results indicated that the competitive interactions among seagrass species were asymmetrical and dependent on plant size. Lastly, seagrass traits including leaf area index and root length controlled carbon stocks in the sediment. TBFs can help to push seagrass research forward by the study of traits from the individual plant level, scaling up their effects on the seagrass community, interspecific competition and, lastly, ecosystem functioning.


Please contact Achim Meyer at the ZMT Academy for the link to particpate.