Possible effects of global environmental changes on Antarctic benthos: a synthesis across five major taxa

Abstract

Because of the unique conditions that exist around the Antarctic continent, Southern Ocean (SO) ecosystems are very susceptible to the growing impact of global climate change and other anthropogenic influences. Consequently, there is an urgent need to understand how SO marine life will cope with expected future changes in the environment. Studies of Antarctic organisms have shown that individual species and higher taxa display different degrees of sensitivity to environmental shifts, making it difficult to predict overall community or ecosystem responses. This emphasizes the need for an improved understanding of the Antarctic benthic ecosystem response to global climate change using a multitaxon approach with consideration of different levels of biological organization. Here, we provide a synthesis of the ability of five important Antarctic benthic taxa (Foraminifera, Nematoda, Amphipoda, Isopoda, and Echinoidea) to cope with changes in the environment (temperature, pH, ice cover, ice scouring, food quantity, and quality) that are linked to climatic changes. Responses from individual to the taxon-specific community level to these drivers will vary with taxon but will include local species extinctions, invasions of warmer-water species, shifts in diversity, dominance, and trophic group composition, all with likely consequences for ecosystem functioning. Limitations in our current knowledge and understanding of climate change effects on the different levels are discussed.

Low abundance and high species richness: the structure of the soft-bottom isopod fauna of a West Antarctic glacial fjord

“…The ongoing changes associated with the climate warming in the Antarctic Peninsula region (Walsh 2009) might also affect isopod assemblages, as they are sensitive to glacial disturbance. If the level of isopod rarity in glacial Antarctic inlets is really as high as that shown by our data, local populations of some species may become extinct in smaller isolated basins directly due to changes in environmental conditions, as shown in scenarios proposed by Ingels et al (2012). Our analysis was based on samples collected 30 years ago and thus can be used as a baseline for further studies, especially those investigating long-term changes in composition and diversity of the benthic fauna.…”

“…Isopods are benthic brooders characterized by a limited dispersal potential, which makes them potentially good indicators of changes associated with various types of natural and anthropogenic disturbance (Veloso et al 2011;Siciński et al 2012;Longo et al 2013). Some species have been shown to be vulnerable to largescale environmental changes observed in the region of the West Antarctic Peninsula (Ingels et al 2012). Specifically, the mobility, physiology and development of benthic isopods may be affected by modification of hydrological and sedimentary regimes (Young et al 2006;Janecki et al 2010).…”

Major impacts of climate change on deep-sea benthic ecosystems

“…The Arctic and many areas of the Antarctic (e.g., western Antarctic Peninsula or WAP) are predicted to undergo more surface-water warming than other parts of the Earth over the next century, which will affect surface production, sea-ice cover, and hence food availability and quality for deep-sea benthic organisms (see Ingels et al, 2012, for Antarctic coastal to deep-sea ecosystems). Parts of the Antarctic Peninsula, including the WAP, are already experiencing the greatest increase in mean annual atmospheric temperature on Earth (Chapman and Walsh, 2007;Clarke et al, 2007;Solomon et al, 2007;Smale and Barnes, 2008), and temperatures at the seafloor in the Southern Ocean are predicted to rise by as much as 0.7°C at abyssal depths and 1.7°C at bathyal depths by 2100 ( Table 2).…”

“…Moreover, different organism groups (e.g., bacteria versus metazoans), and different life stages of the same species (e.g., larvae versus adults), may respond differently and display different degrees of sensitivity to environmental changes (Ingels et al, 2012).…”

Hydrological features above a Southern Ocean seamount inhibit larval dispersal and promote speciation: evidence from the bathyal mytilid Dacrydium alleni sp. nov. (Mytilidae: Bivalvia)

“…Given the importance and potential fragility of Antarctic marine ecosystems, it is imperative to establish robust ecological and taxonomic baselines against which to measure the impacts of our changing climate (Ingels et al 2012;). Shelled, non-swimming molluscs are of primary importance in the modelling of biogeographical patterns as, in addition to not travelling large distances, they also leave long-term evidence of their presence in the form of shells .…”