A new mesocosm system to study the effects of environmental variability on marine species and communities

Christian Pansch,Claas Hiebenthal

doi:10.1002/lom3.10306

Christian Pansch, Claas Hiebenthal

Open Access

https://doi.org/10.1002/lom3.10306

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Abstract

AbstractClimate change will shift mean environmental conditions and also increase the frequency and intensity of extreme events, exerting additional stress on ecosystems. While field observations on extremes are emerging, experimental evidence of their biological consequences is rare. Here, we introduce a mesocosm system that was developed to study the effects of environmental variability of multiple drivers (temperature, salinity, pH, light) on single species and communities at various temporal scales (diurnal ‐ seasonal): the Kiel Indoor Benthocosms (KIBs). Both, real‐time offsets from field measurements or various dynamic regimes of environmental scenarios, can be implemented, including sinusoidal curve functions at any chosen amplitude or frequency, stochastic regimes matching in situ dynamics of previous years and modeled extreme events. With temperature as the driver in focus, we highlight the strengths and discuss limitations of the system. In addition, we examined the effects of different sinusoidal temperature fluctuation frequencies on mytilid mussel performance. High‐frequency fluctuations around a warming mean (+2°C warming, ± 2°C fluctuations, wavelength = 1.5 d) increased mussel growth as did a constant warming of 2°C. Fluctuations at a lower frequency (+2 and ± 2°C, wavelength = 4.5 d), however, reduced the mussels’ growth. This shows that environmental fluctuations, and importantly their associated characteristics (such as frequency), can mediate the strength of global change impacts on a key marine species. The here presented mesocosm system can help to overcome a major short‐coming of marine experimental ecology and will provide more robust data for the prediction of shifts in ecosystem structure and services in a changing and fluctuating world.

Highlights

Global climate models project warming and acidification of the world’s oceans (Rhein et al 2013)
Effects of changed global means of single factors, like warming, acidification, desalination, eutrophication or hypoxia, on single species have been investigated in numerous manipulative experiments and field observations (Pörtner et al 2014)
Diverse approaches, ranging from small-scale laboratory experiments to mesocosms, FOCE systems (Gattuso et al 2014) and field observations have been established over the decades, each of which provide their own benefits (Stewart et al 2013)

Summary

Introduction

Global climate models project warming and acidification of the world’s oceans (Rhein et al 2013). The interaction of eutrophication and warming (faster re-mineralization, lower gas solubility, and increased stable stratification) favors hypoxic conditions (Diaz and Rosenberg 2008; Rabalais et al 2009; Gräwe et al 2013) This leads to an additional increase of coastal acidification (Melzner et al 2013; Waldbusser and Salisbury 2014). Superimposed on these long-term trends, an increase in the variability around mean changes, in the frequency, intensity, Additional Supporting Information may be found in the online version of this article. A severe shortcoming of most marine studies at all levels of complexity, is the exclusion of fluctuations of abiotic (and biotic) drivers from the experimental designs (Thompson et al 2013; Boyd et al 2016; Gunderson et al 2016; Wahl et al 2016; Morash et al 2018)

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