Season affects strength and direction of the interactive impacts of ocean warming and biotic stress in a coastal seaweed ecosystem

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 investigated the effects of ocean warming (OW) and acidification (OA), their combination (OAW), and their natural fluctuations on coastal communities of the western Baltic Sea during all four seasons. These communities are dominated by the perennial and canopy‐forming macrophyte Fucus vesiculosus—an important ecosystem engineer Baltic‐wide. We, additionally, assessed the direct response of organisms to temperature and pH in benchtop experiments, and examined how well organism‐level responses can predict community‐level responses to the dominant driver, OW. OW affected the mesocosm communities substantially stronger than acidification. OW provoked structural and functional shifts in the community that differed in strength and direction among seasons. The organism‐level response to OW matched well the community‐level response of a given species only under warm and cold thermal stress, that is, in summer and winter. In other seasons, shifts in biotic interactions masked the direct OW effects. The combination of direct OW effects and OW‐driven shifts of biotic interactions is likely to jeopardize the future of the habitat‐forming macroalga F. vesiculosus in the Baltic Sea. Furthermore, we conclude that seasonal mesocosm experiments are essential for our understanding of global change impact because they take into account the important fluctuations of abiotic and biotic pressures

Effect of warming and acidification on the defense of Fucus vesiculosus against macrofouling in benthocosm experiments

Defense strength as log effect ratio against macrofouling by Mytilus edulis and Amphibalanus imrovisus. Effect size > 0 indicate an attractive effect of surface-bond metabolites, effect size < 0 an inhibitory effect with strongest defense at lowest values. Responses are displayed in regard to the four treatments: warm (+°C (delta+5)), acidified (-pH (delta +700µatm pCO2)), warm and acidified (+°C -pH), and ambient during four seasons: spring, summer, autumn, winter (n=3) The data set comprised 4 experimental runs: spring experiment (4.4.-10.6.2013), summer experiment 1 (4.7.-17.9.2013), autumn experiment (11.10-16.12.2013), winter experiment (16.1. - 28.3.2014)

Future warming and acidification effects on anti-fouling and anti-herbivory traits of the brown alga Fucus vesiculosus (Phaeophyceae)

Human-induced ocean warming and acidification have received increasing attention over the past decade and are considered to have substantial consequences for a broad range of marine species and their interactions. Understanding how these interactions shift in response to climate change is particularly important with regard to foundation species, such as the brown alga Fucus vesiculosus. This macroalga represents the dominant habitat former on coastal rocky substrata of the Baltic Sea, fulfilling functions essential for the entire benthic community. Its ability to withstand extensive fouling and herbivory regulates the associated community and ecosystem dynamics. This study tested the interactive effects of future warming, acidification, and seasonality on the interactions of a marine macroalga with potential foulers and consumers. F. vesiculosus rockweeds were exposed to different combinations of conditions predicted regionally for the year 2100 (+∆5°C, +∆700 μatm CO2) using multifactorial long-term experiments in novel outdoor benthic mesocosms (“Benthocosms”) over 9–12-week periods in four seasons. Possible shifts in the macroalgal susceptibility to fouling and consumption were tested using consecutive bioassays. Algal susceptibility to fouling and grazing varied substantially among seasons and between treatments. In all seasons, warming predominantly affected anti-fouling and anti-herbivory interactions while acidification had a subtle nonsignificant influence. Interestingly, anti-microfouling activity was highest during winter under warming, while anti-macrofouling and anti-herbivory activities were highest in the summer under warming. These contrasting findings indicate that seasonal changes in anti-fouling and anti-herbivory traits may interact with ocean warming in altering F. vesiculosus community composition in the future

Effect of warming and acidification on the defense of Fucus vesiculosus in benthocosm experiments

Human-induced ocean warming and acidification have received increasing attention over the past decade and are considered to have substantial consequences for a broad range of marine species and their interactions. Understanding how these interactions shift in response to climate change is particularly important with regard to foundation species, such as the brown alga Fucus vesiculosus. This macroalga represents the dominant habitat former on coastal rocky substrata of the Baltic Sea, fulfilling functions essential for the entire benthic community. Its ability to withstand extensive fouling and herbivory regulates the associated community and ecosystem dynamics. This study tested the interactive effects of future warming, acidification, and seasonality on the interactions of a marine macroalga with potential foulers and consumers. F. vesiculosus rockweeds were exposed to different combinations of conditions predicted regionally for the year 2100 (+∆5°C, +∆700 μatm CO2) using multifactorial long-term experiments in novel outdoor benthic mesocosms (“Benthocosms”) over 9–12-week periods in four seasons. Possible shifts in the macroalgal susceptibility to fouling and consumption were tested using consecutive bioassays. Algal susceptibility to fouling and grazing varied substantially among seasons and between treatments. In all seasons, warming predominantly affected anti-fouling and anti-herbivory interactions while acidification had a subtle nonsignificant influence. Interestingly, anti-microfouling activity was highest during winter under warming, while anti-macrofouling and anti-herbivory activities were highest in the summer under warming. These contrasting findings indicate that seasonal changes in anti-fouling and anti-herbivory traits may interact with ocean warming in altering F. vesiculosus community composition in the future

Effect of warming and acidification on the defense of Fucus vesiculosus against microfouling in benthocosm experiments

Defense strength as log effect ratio against microfouling by Bacillus sp., Cytophaga sp. and Vibrio sp. (averaged). Effect size > 0 indicates an attractive effect of surface-bond metabolites, effect size < 0 an inhibitory effect with the strongest defense at lowest values. Responses are detailed with regards to the four treatments: warm (+°C (delta+5)), acidified (-pH (delta +700µatm pCO2)), warm and acidified (+°C -pH), and ambient during four seasons: spring, summer, autumn, winter (n=3). The data set comprised 4 experimental runs: spring experiment (4.4.-10.6.2013), summer experiment 1 (4.7.-17.9.2013), autumn experiment (11.10-16.12.2013), winter experiment (16.1. - 28.3.2014)

Shifted Coastal Communities and Ecosystem Functions under Predicted Warming and Acidification

The effects of ocean warming and acidification on Eastern Mediterranean coastal benthic communities were studied in a long-term research using benthic mesocosms ('benthocosms'). Temperature and pH treatments complied with the near-past, present and predicted-future levels. While biodiversity indices did not change significantly with warming (+3 ºC) and acidification (-0.5 pH units), community composition shifted from native to non-indigenous species dominance, and the abundance of calcifying species increased. In the summer, community functions presented a shift from autotrophic to heterotrophic system

The carbon turnover response to thermal stress of a dominant coralline alga on the fast warming Levant coast

Marine organisms in the Mediterranean Sea experience the highest temperatures, salinities and oligotrophic conditions in its easternmost part along the eastern shores of the Levantine basin. Over the past three decades this region has warmed by ca. 1.5–3.0°C with current winter and summer extremums of 17°C and 31°C, respectively. In this study, we tested the response of the native abundant articulated coralline red alga Ellisolandia elongata to this warming. Coralline algae play a key role in coastal ecosystems by structuring marine habitats, providing shelter for a myriad of species, and substantially influencing the coastal carbon budget. Despite being ubiquitous along the Levantine coasts, coralline's ecology, physiology, and biogeochemical role are nearly unknown as well as their performance under different temperatures. Measurements of primary production, respiration and calcification in the temperatures range 15–35°C, which represent past, present and predicted local annual conditions, indicated two physiological tipping points: 1) metabolic breakdown above 31°C; 2) metabolic shift at 23°C, possibly promoting seasonal algal heterotrichy (perennation of the alga without its fronds). Annual production rates were evaluated under the current and predicted temperature regimes indicating a loss of ca. one third of the organic carbon and carbonate production by corallines contributed to the shallow Levantine coast in the upcoming decades. We predict that with continued warming, Eastern Mediterranean corallines will experience a westward range contraction, initiating with phenological shifts, followed by performance declines and population decreases, ending with local extinctions

Comparing clinical characteristics of pediatric patients with pancreatic diabetes to patients with type 1 diabetes: A matched case-control study

Background: Only few studies have been conducted on pancreatic diabetes and data from large epidemiological studies are missing. Our main objective was to study the most important differences and similarities between pediatric individuals with pancreatic diabetes and type 1 diabetes (T1D). Methods: Patients <20 years of age were identified from the diabetes patient followup registry (DPV). Data of the most recent treatment year between January 2000 and March 2018 were aggregated. Propensity score was used to match individuals with pancreatic diabetes to individuals with T1D. Matching was conducted one-toone by sex, age, diabetes duration, body mass index SD score (BMI-SDS), and migration background. Results: We studied 731 individuals with pancreatic diabetes and 74 460 with T1D. In the matched cohort of 631 pairs, HbA1c was significantly lower in pancreatic diabetes (7.4% [95% confidence interval: 7.2; 7.5%]) compared to T1D patients (8.7% [8.5; 8.8%]). Daily insulin dose (0.80 IU/kg [0.77; 0.84] vs 0.86 IU/kg [0.82; 0.90]) and insulin pump use (13.3% [10.7; 16.4] vs 22.1% [19.0; 25.6%]) were lower in patients with pancreatic diabetes. However, event rates of severe hypoglycemia were similar between pancreatic and T1D patients (8.8 [5.4; 14.2] vs 9.6 [5.9; 15.6] events per 100 patient years). Conclusions: With the use of robust epidemiological data, our study improves the knowledge on clinical characteristics in pediatric individuals with pancreatic diabetes. Moreover, our results serve as a basis to reconsider treatment options and for discussing clinical practice guidelines for patients with this rare medical condition

Seasonal mesocosm community experiments with warming and acidification treatments in Kiel Outdoor Benthocosms

Seasonal mesocosm community experiments: Four successive runs of ca 10 weeks in 12 outdoor mesocosms (ca 1400 L) with flow-through and a orthogonally crossed warming ("ambient" temperature vs warming by 5°C = "OW") and acidification ("ambient" CO2 vs increase by 700 µatm = "OA" and combined warming and acidification = "OWA" ) treatment. The tanks were started with the same community composition (Fucus vesiculosus; mesograzers Idotea spp., Gammarus spp., Littorina littorea; seastar Asteria rubens, filter feeders Balanus improvisus, Mytilus edulis); details in Wahl et al. 2015. Seasonal responses to the various treatments were (a) mean daily relative Fucus length growth of thallus tips (%), (b) relative Mytilus shell length growth (%), (c) mean daily relative growth of Balanus basal plate, (d-f) the relative population size changes of the three mesograzer species expressed as the log of final divided by initial abundances, (g) the relative survival of Asterias (%)