Model simulation of seasonal growth of Fucus vesiculosus in its benthic community

Abstract

Numerical models are a suitable tool to quantify impacts of predicted climate change on complex ecosystems but are rarely used to study effects on benthic macroalgal communities. Fucus vesiculosus L. is a habitat‐forming macroalga in the Baltic Sea and alarming shifts from the perennial Fucus community to annual filamentous algae are reported. We developed a box model able to simulate the seasonal growth of the Baltic Fucus–grazer–epiphyte system. This required the implementation of two state variables for Fucus biomass in units of carbon (C) and nitrogen (N). Model equations describe relevant physiological and ecological processes, such as storage of C and N assimilates by Fucus, shading effects of epiphytes or grazing by herbivores on both Fucus and epiphytes, but with species‐specific rates and preferences. Parametrizations of the model equations and required initial conditions were based on measured parameters and process rates in the near‐natural Kiel Outdoor Benthocosm (KOB) experiments during the Biological Impacts of Ocean Acidification project. To validate the model, we compared simulation results with observations in the KOB experiment that lasted from April 2013 until March 2014 under ambient and climate‐change scenarios, that is, increased atmospheric temperature and partial pressure of carbon dioxide. The model reproduced the magnitude and seasonal cycles of Fucus growth and other processes in the KOBs over 1 yr under different scenarios. Now having established the Fucus model, it will be possible to better highlight the actual threat of climate change to the Fucus community in the shallow nearshore waters of the Baltic Sea.

Methane dynamics in the Baltic Sea: investigating concentration, flux and isotopic composition patterns using the coupled physical-biogeochemical model BALTSEM-CH4 v1.0

“…BALTSEM-CH4 v1.0 does not differentiate between vegetated and unvegetated areas, which means that this CH4 sourceand its contribution to outgassingcould not be addressed here, which consequently represents another gap in our current understanding. Both species distribution models and process-based models for vegetation exist (e.g., Lappalainen et al, 2019;Graiff et al, 2020), but to our knowledge do not include CH4 dynamics. Hence, the inclusion of CH4 in vegetation models could potentially serve as an objective for future scientific projects.…”

Seasonal Photophysiological Performance of Adult Western Baltic Fucus vesiculosus (Phaeophyceae) Under Ocean Warming and Acidification

“…The KOB facility is exposed to ambient light (irradiance and photoperiod) conditions year-round. Photosynthetically active radiation (PAR) data were obtained from the German Weather Service (DWD, for details see Graiff et al, 2020). Water conditions were kept as close as possible to the real ambient conditions of the Kiel Fjord, including their fluctuations.…”