Angelika Graiff

• Dr. rer. nat.
• PostDoc Position at University of Rostock

Reliable net primary production (NPP) estimations of kelp forests are important to evaluate their C-fixation potential. Photosynthetic oxygen measurements can be converted to C-fixation using photosynthetic quotients (PQs). Although there is a known high variability in PQs, the extent and the consequences for NPP is understudied in kelp species. Th...

The consequences of a year-round warming scenario on the photosynthetic performance of kelp species are unknown. In times of global warming, fundamental photosynthesis data are important due to the high temperature dependence. Seasonal photosynthetic performance was quantified in the kelp Laminaria hyperborea sampled along a depth gradient (2, 4 an...

This paper was initiated by a multidisciplinary Topic Workshop in the frame of the Deutsche Forschungsgemeinschaft Priority Program 1158 “Antarctic Research with Comparative Investigations in Arctic Ice Areas”, and hence it represents only the national view without claiming to be complete but is intended to provide awareness and suggestions for the...

Coastal kelp forests produce substantial marine carbon due to high annual net primary production (NPP) rates, but upscaling of NPP estimates over time and space remains difficult. We investigated the impact of variable underwater photosynthetically active radiation (PAR) and photosynthetic parameters on photosynthetic oxygen production of Laminaria...

Table S1. Results of the one-way ANOVAs or Kruskal–Wallis’s tests from the experiment with salinity variation performed with Bostrychia calliptera and B. montagnei. F and χ² refer to the F and χ² calculated of the ANOVAs and Kruskal–Wallis’s tests, respectively. df refers to the degrees of freedom. Fv/Fm: maximum quantum yield; α: light utilization...

Table S1. Results of the one-way ANOVAs or Kruskal–Wallis’s tests from the light stress experiment performed with Bostrychia calliptera and B. montagnei. F and χ² refer to the F and χ² calculated of the ANOVAs and Kruskal–Wallis’s tests, respectively. df refers to the degrees of freedom. Fv/Fm: maximum quantum yield; α: light utilization coefficien...

Salinization in tropical estuarine environments is expected as a result of climate change. The physiological performance of mangrove-associated key macroalgae can negatively be affected by increased salinity in such habitats. Thus, we analyzed photobiological and biochemical responses of the closely related red algae Bostrychia calliptera and Bostr...

Chlorophyll absorbance spectrum of Bostrychia calliptera. Peaks 1 and 3 refer to chlorophyll a (λ = 664 and 410 nm, respectively).

Bostrychia calliptera bleaching due to mycosporine-like amino acid degradation after culturing it under different photon flux densities for 14 days.

Chlorophyll absorbance spectrum of Bostrychia montagnei. Peaks 1 and 4 refer to chlorophyll a (λ = 664 and 410 nm, respectively).

High Performance Liquid Chromatography (HPLC) chromatograms of Bostrychia calliptera (a) and B. montagnei (b) after culturing the macroalgae under 170 µmol photons m–2 s–1 for 14 days. Peak 1: Palythine; Peak 2: Asterina-330; Peak 3: MAA-321; Peak 4: Porphyra-334; Peak 5: MAA-356; Peak 6: MAA-330; Peak 7: Shinorine. mAU: Absorbance units. Asterisks...

Increased solar radiation on the Earth’s surface is expected due to global change. Mangrove macroalgae can be negatively affected by increased solar radiation, since some species, such as Bostrychia spp. have been characterized as typical “shade” plants. Thus, we investigated the effects of increasing photon flux densities (PFDs: 170, 267, 443, 638...

Simple Summary The brown seaweed Fucus vesiculosus is the dominant and the most ecologically crucial primary producer and habitat founder in the Baltic Sea. In the shallow coastal zone, F. vesiculosus is particularly exposed to strongly and rapidly changing environmental conditions due to global change. This study examines how single and joint effe...

Shallow coastal marine ecosystems are exposed to intensive warming events in the last decade, threatening keystone macroalgal species such as the bladder wrack (Fucus vesiculosus, Phaeophyceae) in the Baltic Sea. Herein, we experimentally tested in four consecutive benthic mesocosm experiments, if the single and combined impact of elevated seawater...

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 d...

The plea for using more "realistic," community-level, investigations to assess the ecological impacts of global change has recently intensified. Such experiments are typically more complex, longer, more expensive, and harder to interpret than simple organism-level benchtop experiments. Are they worth the extra effort? Using outdoor mesocosms, we in...

Ecological impact of global change is generated by multiple synchronous or asynchronous drivers which interact with each other and with intraspecific variability of sensitivities. In three near-natural experiments, we explored response correlations of full-sibling germling families of the seaweed Fucus vesiculosus towards four global change drivers...

Eight benthic diatom taxa (Actinocyclus octonarius, Melosira moniliformis, Halamphora sp. 1, Halamphora sp. 2, Navicula perminuta, Navicula phyllepta, Nitzschia dubiiformis, Nitzschia pusilla) were isolated from sediments sampled in the southern coastal brackish Baltic Sea and established as unialgal cultures. The coastal shallow water sampling are...

Ocean warming and acidification may substantially affect the reproduction of keystone species such as Fucus vesiculosus (Phaeophyceae). In four consecutive benthic mesocosm experiments, we compared the reproductive biology and quantified the temporal development of Baltic Sea Fucus fertility under the single and combined impact of elevated seawater...

Floating seaweeds serve as dispersal agents for various organisms, but their survival at the sea surface may be compromised by physiological stress and epibiont overgrowth. Most previous experiments have been conducted in laboratory mesocosms where epibiont colonization is limited, but in their natural environment floating seaweeds are frequently o...

Coastal marine ecosystems have been under high anthropogenic pressure and it can be assumed that prevalent local perturbation interacts with rising global stressors under proceeding climate change. Understanding their effective pathways and cumulative effects is of high relevance not only with regard to future risk assessment, but also for current...

Ocean acidification and warming (OAW) are occurring globally. Additionally, at a more local scale the spreading of hypoxic conditions is promoted by eutrophication and warming. In the semi-enclosed brackish Baltic Sea, occasional upwelling in late summer and autumn may expose even shallow-water communities including the macroalga Fucus vesiculosus...

Nutrient concentrations in the experimental boxes. Nutrient concentrations within the experimental germling boxes before (A, B) and after (C, D) the bi-weekly addition of the nutrients (PO4, NO3, NO2) as well as initial NH4 conditions in μmol L-1 in July and August. Initial nutrient concentrations were measured six times per month in the main KOB t...

Marine multicellular organisms in composition with their associated microbiota—representing metaorganisms—are confronted with constantly changing environmental conditions. In 2110, the seawater temperature is predicted to be increased by ~5°C, and the atmospheric carbon dioxide partial pressure (pCO2) is expected to reach approximately 1000 ppm. In...

Rising seawater temperature and CO2 concentrations (ocean acidification) represent two of the most influential factors impacting marine ecosystems in the face of global climate change. In ecological climate change research, full-factorial experiments performed across seasons in multispecies, cross-trophic-level settings are essential as they permit...

GlobalClimate change exposes brown algal Fucus vesiculosus populations to increasing temperature and pCO2, which may threaten individuals, in particular the early life-stages. Genetic diversity of F. vesiculosus populations is low in the Baltic compared to Atlantic populations. This might jeopardise their potential for adaptation to environmental c...

Warming and acidification of the oceans as a consequence of increasing CO2-concentrations occur at large scales. Numerous studies have shown the impact of single stressors on individual species. However, studies on the combined effect of multiple stressors on a multi-species assemblage, which is ecologically much more realistic and relevant, are st...

Warming and acidification of the oceans as a consequence of increasing CO2-concentrations occur at large scales. Numerous studies have shown the impact of single stressors on individual species. However, studies on the combined effect of multiple stressors on a multi-species assemblage, which is ecologically much more realistic and relevant, are st...

Seaweeds provide important ecosystem services in coastal areas, and loss of these macrophytes due to anthropogenic global change and warming is a worldwide concern. Fucus vesiculosus L. (Phaeophyceae) is the most abundant and hence ecologically most important primary producer, carbon sink and habitat provider in the western Baltic Sea. Therefore, w...

The polysaccharide laminarin (β-1,3-glucan) is used as a long-term carbon storage compound in brown algae. This chemical storage form of carbon enables perennial brown algae in seasonally fluctuating ecosystems to uncouple growth from photosynthesis, i.e., most of these plants grow as seasonal anticipators in winter based on remobilization of lamin...

Genetic diversity of baltic F. vesiculosus is low compared to other populations which might jeopardize their potential for adaptation to climate change. Especially the early life-stage F. vesiculosus may be threaten by ocean warming and acidification. To test this, we exposed F. vesiculosus germlings to warming and acidification in the near-natural...

Fucus vesiculosus L. (Phaeophyceae) is the most abundant and hence ecologically most important primary producer, carbon sink and habitat provider in the western Baltic Sea. All F. vesiculosus L. specimens were collected on 23 April 2014 from a depth of 0.2-1 m in the non-tidal Kiel Fjord, western Baltic Sea (54°27'N; 10°12'E), where this species fo...

In search of a meaningful stress indicator for Fucus vesiculosus we found that the often used quantitative determination procedures for the polysaccharide laminarin (beta-1,3-glucan) result in different kind of problems, uncertainties and limitations. This chemical long-term storage form of carbon enables perennial brown algae in seasonally fluctua...

Several large kelp species are capable of long-distance dispersal via rafting. However, seasonal changes in environmental conditions at the sea surface may variably affect the physiological status of the floating thalli; challenging conditions during summer may accelerate disintegration and cause rapid sinking. We used the bull kelp Durvillaea anta...