Warming by 1°C Drives Species and Assemblage Level Responses in Antarctica’s Marine Shallows

Abstract

Forecasting assemblage-level responses to climate change remains one of the greatest challenges in global ecology [1, 2]. Data from the marine realm are limited because they largely come from experiments using limited numbers of species [3], mesocosms whose interior conditions are unnatural [4], and long-term correlation studies based on historical collections [5]. We describe the first ever experiment to warm benthic assemblages to ecologically relevant levels in situ. Heated settlement panels were used to create three test conditions: ambient and 1°C and 2°C above ambient (predicted in the next 50 and 100 years, respectively [6]). We observed massive impacts on a marine assemblage, with near doubling of growth rates of Antarctic seabed life. Growth increases far exceed those expected from biological temperature relationships established more than 100 years ago by Arrhenius. These increases in growth resulted in a single "r-strategist" pioneer species (the bryozoan Fenestrulina rugula) dominating seabed spatial cover and drove a reduction in overall diversity and evenness. In contrast, a 2°C rise produced divergent responses across species growth, resulting in higher variability in the assemblage. These data extend our ability to expand, integrate, and apply our knowledge of the impact of temperature on biological processes to predict organism, species, and ecosystem level ecological responses to regional warming.

Plasticity and environmental heterogeneity predict geographic resilience patterns of foundation species to future change

“…Advances in macroecology suggest that permanent environmental mosaics, defined by spatial overlaps of non-monotonic environmental gradients ( 7 ), as well as regional adaption or acclimatization ( 8 – 10 ), dictate geographic variations in species performance and sensitivity to environmental change in marine ecosystems. Key to these works is that responses vary among populations and individual taxa ( 6 , 8 ), which often play disproportionately strong roles in structuring benthic communities ( 11 ). Thus, species-specific biological mechanisms driving organismal variability may shape differential regional responses of foundation species to co-occurring multiple drivers.…”

The short-term combined effects of temperature and organic matter enrichment on permeable coral reef carbonate sediment metabolism and dissolution

“…It is important to note that the established Arrhenius relationships in the literature suggest that development and growth rates should increase at a rate of 7-12 % • C −1 of warming (Clarke, 2003), much lower than the observed 74 and 42 % increase in R and GPP respectively per 1 • C of warming in this study. However, recent work in the Antarctic by Ashton et al (2017) on marine benthic assemblages showed that, in some species, the growth rate exhibited a 100 % increase per 1 • C of warming, yielding Q 10 values around 1000. Therefore, while the temperature sensitivity estimates reported in this paper and in Trnovsky et al (2016) exceed the expected rate for biological reactions and enzyme activity, evidence exists in other benthic marine environments to support the notion that the impact of temperature on biochemical processes may be more complex than previously thought at the organism level (Ashton et al, 2017).…”

“…Furthermore, the majority of warming studies on marine sediments have been performed ex situ in more poleward latitudes (temperate to arctic environments) over a wide range of temperatures (2-30 • C; e.g. Tait and Schiel, 2013;Hancke et al, 2014;Ashton et al, 2017). The bacterial communities residing in marine sediments generally display a hyperbolic temperature-production relationship where GPP increases with T (∼ +32 % per 1 • C increase) until an optimal rate is reached roughly +2-3 • C above naturally observed seasonal maxima.…”

MicroRNAs buffer genetic variation at specific temperatures during embryonic development

“…As a consequence, the ability to respond to "perturbing" cues, such as environmental changes, is a key feature to all organisms on Earth (Ashton et al, 2017;Kuntz and Eisen, 2014). The progression of a particular event needs to be coordinated to the timescale of development across the whole embryo.…”