Automated monitoring of plankton in lakes: what controls biodiversity? Advancing ecology and sharing the knowledge

• Research unit: COST
• Project number: C14.0061

Key words (English)

Lakes; ecoystem resilience; plankton; biodiversity; community assembly; automated monitoring; flowcytometry; image analysis

Research programs (English)

COST-Action ES1201 - NETLAKE - NETworking LAKe observatories in Europe

Short description (English)

Lakes are hotspots of biodiversity. At the same time lakes are under exceptional pressure from environmental change. Lakes accumulate nutrients, pollutants and other stressors from their catchments and act as sentinels of change. Under environmental pressure lakes with clear water and rich aquatic biodiversity may suddenly collapse into turbid systems, characterised by blooms of toxic cyanobacetria. Recovery from eutrophication has cost billions in Europe alone, and climate warming threatens to undo much of these efforts. Recent research demonstrates that if we are to better prepare our lakes for ongoing environmental change we should maintain and strengthen biodiversity, in paricular at the planktonic base of the foodweb. For this we need a deep understanding of the controlling mechanisms. Monitoring environmental change, and the efforts to maintain and enhance biodoversity is crucial if we are to understand how our lakes are functioning. The NETLAKE COST Action brings efforts of automated lake monitoring across Europe together. With this proposal we aim to make an important contribution to NETLAKE by advancing the automated, high frequency sampling and analysis of phyto- and zooplankton in lakes. We propose - for the first time - to study the process of community assembly across two trophic lessons and identify the abiotic and biotic drivers that control plankton biodiversity. Equally important we aim to efficiently disseminate the knowledge we obtain to all COST partners.

Further information (English)

Full name of research-institution/enterprise: University of Geneva - Faculty of Sciences Department F.-A. Forel for Environmental and Aquatic Sciences + Institute for Environmental Sciences, Uni Carl Vogt - Room C211

Partners and International Organizations (English)

AT; BA; HR; CZ; DK; EE; FI; FR; MK; DE; EL: HU; IE; IL; IT; LV; NL; NO; PL, RS; ES; SE; TR; UK; AL; US; NZ; AU;

Abstract (English)

The mechanisms underlying species diversity and coexistence have long puzzled ecologists. Communities of coexisting species arise as the result of ecological and evolutionary interactions. There is a large body of theory that underlies species coexistence, however, empirical evidence on how such processes operate in nature is still scarce. One theory explaining co-existence and biodiversity is referred to as emergent neutrality. In simple words there are two ways to co-exist, being different enough – when niches stabilise co-existence – or being similar enough, co-existence on neutral grounds. In a niche based view species differ in key traits involved in e.g. resource acquisition or defence against predation and disease. In a neutral view species from the same community do not differ in key traits. We hypothesise that niche and neutrality interact and together determine the possibility for co-existence and biodiversity. Freshwater phytoplankton is an excellent model to test this hypothesis, since it is well known that phytoplankton species compete for just a small number of potentially limiting resources, although a remarkable number of species coexist in a relatively homogenous environment of a well-mixed lake, the so-called paradox of the plankton. Variation in functional traits can influence relative fitness differences and contribute to competitive inequalities. Individual size is defined as the most relevant trait, due to its central role in defining other traits related to physiology and interactions between taxa. In our project we seek to gain a more complete understanding how (i) phytoplankton size explains species co-existence in laboratory experiments, and (ii) to apply this knowledge to the field, also using existing long term monitoring datasets, ultimately as a basis for adaptive water-management of lakes and reservoirs. In a first experiment – presently ongoing - cyanobacterial species with a wide range of size (up to several orders of magnitude) are being used to test our key hypothesis that niche and neutrality augment each other. In our experimental design we test for successful invasion from rare as evidence for density dependence, a hallmark of niche based interactions. Co-existence on neutral grounds, in contrast, would not be characterised by invasion from rare. In this way, by systematically testing for the role of size differences in density dependence we aim to unravel the relative contributions of niche vs. neutrality in phytoplankton co-existence. Other than experiments we have indeed started to analyse existing phytoplankton long term monitoring datasets from Swiss lakes which we will use to investigate if niche differentiation (in space and time) promotes species coexistence in heterogeneous lake environments. In this we will also look for evidence if and how two major ongoing trends in Swiss lake ecosytems – re-oligotrophication and climate warming – contribute to a heterogeneous lake environment and the promotion of biodiversity.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C14.0061