Effects of temperature and interspecific competition on growth and photosynthesis of two endemic Antarctic Desmarestia species

Zacher, Katharina; Savaglia, Valentina; Bartsch, Inka

doi:10.1127/algol_stud/2016/0269

Cited by 5 publications

(15 citation statements)

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“…However, not just season but also other factors such as age and size of the algae may influence growth rates, as it has been found in other studies (e.g. Khailov 1976;Wiencke 1990;Zacher et al 2016). Current and modelled warming in Antarctica (Clark et al 2013) does not seem to threaten the ecosystem builders D. anceps and D. menziesii as growth until 7 °C is not reduced compared to lower temperatures and material was healthy without any bleaching.…”

Section: Discussionsupporting

confidence: 51%

“…Generally, growth of both Desmarestia species was too low to detect treatment effects. Wiencke andtom Dieck (1989, 1990) detected optimal growth rates for these species at temperatures ≤ 5 °C, whereas Zacher et al (2016) could show higher growth rates for D. anceps at 5 °C compared to 0 °C in a study with cultured material. Defined as season anticipators (Kain 1989;Wiencke 1990;Gómez and Wiencke 1997), D. menziesii and D. anceps start to grow only under short day conditions in late winter/ spring, even under the sea ice.…”

Section: Discussionmentioning

confidence: 98%

“…Besides the regulatory role of abiotic factors, interspecific competition is often considered the major selective force in algal communities determining diversity, species distribution and the biomass and structure of algal communities (Nabivailo and Titlyanov 2006;Barner et al 2016;Traiger and Konar 2017). Few studies have investigated interspecific relationships among benthic seaweeds occupying the same niche (Reed 1990;Xu et al 2013;Nabivailo et al 2014;Chen et al 2015;Barner et al 2016), particularly at high latitudes (but see Zacher et al 2016). Little information is available on the interplay between abiotic and biotic conditions, which is fundamental in order to understand the succession of seaweed communities (Nabivailo et al 2014;Barner et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Previous investigations indicated the lack of multifactorial experiments (Wiencke et al 2006) and the need to work with field material (Zacher et al 2016) when evaluating the fate of unique polar ecosystems. Although temperature alone is not likely to endanger the performance of important Antarctic seaweeds (Müller et al 2009), interaction with other factors such as irradiance and co-cultivation with other species may modify algal responses.…”

Section: Introductionmentioning

confidence: 99%

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Physiological response to irradiance, temperature and co-cultivation in Antarctic engineering brown algae (Desmarestia menziesii and D. anceps)

et al. 2019

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The Western Antarctic Peninsula (WAP) is a hot spot of global warming, including decreased sea-ice cover during winter and increased sedimentation during summer due to glacial melt. Subsequently, an altered irradiance and temperature regime in the water column may affect the performance of primary producers and change competitive structures. The brown, subtidal macroalgae Desmarestia menziesii and D. anceps are ecosystem engineers and of extreme importance for the Antarctic coastal ecosystem. Individuals of both species were collected from the field during the austral summer and exposed in two experiments to different temperatures (2 and 7 °C) or different irradiances (high and low) in combination with co-culturing the two algal species together (two-factorial design). No temperature, irradiance or co-cultivation effects on growth rates of D. menziesii and D. anceps were detected, but effects were possibly masked by the very low growth rates. Both D. menziesii and D. anceps are season anticipators, showing highest growth in late winter/spring and a dormancy state during summer. Photosynthetic efficiency was usually higher at 2 °C and low irradiance conditions compared to 7 °C and high irradiance and no co-culturing effects were detected. Parameters derived from P-E curves (rETR max , E k and α) were higher in D. menziesii compared to D. anceps, reflecting zonation patterns in the field. Future multifactorial experiments, taking seasons and different life-stages into account, are particularly needed to elucidate year-round effects of global warming on macroalgal key species that form the energetic base of the Antarctic coastal food webs.

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Section: Discussionsupporting

confidence: 51%

Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Physiological response to irradiance, temperature and co-cultivation in Antarctic engineering brown algae (Desmarestia menziesii and D. anceps)

et al. 2019

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“…These are considered as the three treatments and will be further referred to as “ Desmarestia ,” “ Palmaria ,” and “control.” The molar C : N ratio of the algae was 14 for Desmarestia and 8 for Palmaria . The macroalgae had previously been grown from gametophytic stock cultures (for details, see e.g., Zacher et al []). After the development of young sporophytes, both species were cultured in NaH 13 CO 3 ‐ and 15 NH 4 Cl‐labeled medium for 2 weeks, of which the labeling success was 11 ( Desmarestia ) to 17 ( Palmaria ) at% 13 C and 38 ( Desmarestia ) to 34 ( Palmaria ) at% 15 N. When sufficient biomass was available, the macroalgae were harvested, washed to remove the labeled dissolved inorganic carbon (DIC) and dissolved inorganic nitrogen (DIN), and freeze dried.…”

Section: Methodsmentioning

confidence: 99%

Degradation of macroalgal detritus in shallow coastal Antarctic sediments

Braeckman

Pasotti

Vázquez

et al. 2019

Limnology & Oceanography

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Glaciers along the western Antarctic Peninsula are retreating at unprecedented rates, opening up sublittoral rocky substrate for colonization by marine organisms such as macroalgae. When macroalgae are physically detached due to storms or erosion, their fragments can accumulate in seabed hollows, where they can be grazed upon by herbivores or be degraded microbially or be sequestered. To understand the fate of the increasing amount of macroalgal detritus in Antarctic shallow subtidal sediments, a mesocosm experiment was conducted to track 13C‐ and 15N‐labeled macroalgal detritus into the benthic bacterial, meiofaunal, and macrofaunal biomass and respiration of sediments from Potter Cove (King George Island). We compared the degradation pathways of two macroalgae species: one considered palatable for herbivores (the red algae Palmaria decipiens) and other considered nonpalatable for herbivores (the brown algae Desmarestia anceps). The carbon from Palmaria was recycled at a higher rate than that of Desmarestia, with herbivores such as amphipods playing a stronger role in the early degradation process of the Palmaria fragments and the microbial community taking over at a later stage. In contrast, Desmarestia was more buried in the subsurface sediments, stimulating subsurface bacterial degradation. Macrofauna probably relied indirectly on Desmarestia carbon, recycled by bacteria and microphytobenthos. The efficient cycling of the nutrients and carbon from the macroalgae supports a positive feedback loop among bacteria, microphytobenthos, and meiofaunal and macrofaunal grazers, resulting in longer term retention of macroalgal nutrients in the sediment, hence creating a food bank for the benthos.

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