Arctic rhodolith beds and their environmental controls (Spitsbergen, Norway)

Abstract

Coralline algae (Corallinales, Rhodophyta) that form rhodoliths are important ecosystem engineers and carbonate producers in many polar coastal habitats. This study deals with rhodolith communities from Floskjeret (78A degrees 18'N), Krossfjorden (79A degrees 08'N), and Mosselbukta (79A degrees 53'N), off Spitsbergen Island, Svalbard Archipelago, Norway. Strong seasonal variations in temperature, salinity, light regime, sea-ice coverage, and turbidity characterize these localities. The coralline algal flora consists of Lithothamnion glaciale and Phymatolithon tenue. Well-developed rhodoliths were recorded between 27 and 47 m water depth, while coralline algal encrustations on lithoclastic cobbles were detected down to 77 m water depth. At all sites, ambient waters were saturated with respect to both aragonite and calcite, and the rhodolith beds were located predominately at dysphotic water depths. The rhodolith-associated macrobenthic fauna included grazing organisms such as chitons and echinoids. With decreasing water depth, the rhodolith pavements were regularly overgrown by non-calcareous Polysiphonia-like red algae. The corallines are thriving and are highly specialized in their adaptations to the physical environment as well as in their interaction with the associated benthic fauna, which is similar to other polar rhodolith communities. The marine environment of Spitsbergen is already affected by a climate-driven ecological regime shift and will lead to an increased borealization in the near future, with presently unpredictable consequences for coralline red algal communities

Latitudinal trends in stable isotope signatures and carbon concentrating mechanisms of northeast Atlantic rhodoliths

“…This specimen was most closely related to L. Teichert et al (2014). Our molecular analysis confirmed that these samples were dominated by L. glaciale, but we also identified a specimen of L. 15 lemoineae Adey from our sub-sampling of this collection.…”

Polar coralline algal CaCO<sub>3</sub>-production rates correspond to intensity and duration of the solar radiation

“…Teichert et al (2012Teichert et al ( , 2014 also showed obvious similarities between the populations, with Lithothamnion glaciale as the dominating photoautotrophic organism at water depths around 45 m, appearing as encrustations or rhodoliths. The colonized substrate is mainly made up of glaciogenic debris and dropstones, and grazing organisms like chitons and echinoids are present at all sites, presumably contributing to keep the rhodoliths free from epibionts (Steneck, 1986).…”

“…The rhodoliths also act as bioengineers sensu Jones et al (1994) and provide microenvironments for the benthic organisms, which therefore depend on substantial rhodolith growth. Teichert et al (2012Teichert et al ( , 2014; note increased CaCO 3 production rate in combination with deviating water depth at NKB #714. To gain data on the annual rhodolith CaCO 3 production, a method was used that enabled the analysis of large sample sizes.…”

“…All sites are characterized by similar physical and biological environmental conditions, and the actual thriving of the coralline red algae is obvious. For a thorough description of the investigations at the coralline red algal and rhodolith beds and the associated environment, please refer to Teichert et al (2012) for Nordkappbukta and to Teichert et al (2014) for Floskjeret, Krossfjorden, and Mosselbukta. Rhodoliths and coralline red algae were collected using the following approach.…”

“…The resulting CaCO 3 production rates (excluding the shallow water control group from Nordkappbukta) were plotted against the physical parameters water depth, seawater calcite saturation (snapshot conditions recorded during MSM 02/03 expedition of RV Maria S. Merian; see also Teichert et al (2012Teichert et al ( , 2014), annual mean temperature (data from LEVI-TUS 94, 2013), duration of sea ice cover (data from Svendsen et al, 2002;Nilsen et al, 2008;Spreen et al, 2008; AMSR-E Sea Ice Maps, 2013), geographical latitude, and duration of the polar night (data from USNO Sun Rise Tables, 2013) at each site. The results were checked for correlations using reduced major axis algorithm and Levene's test for homogeneity of variance based on means (one-way ANOVA).…”