|Friday, July 09|
Climate change and a new dominant seaweed on the Atlantic coast of Nova Scotia
* David Garbary, St. Francis Xavier University, Canada
Megan Fass, St. Francis Xavier University
Herb Vandermeulen, St. Francis Xavier University
Carolyn Bird, St. Francis Xavier University
Fucus serratus was introduced into Nova Scotia in the 19th century from western Europe and has become a dominant component of the subtidal flora in the southern Gulf of St. Lawrence and the shores surrounding Cape Breton Island. Here, we report a major change in geographic distribution of F. serratus on the Atlantic coast of Nova Scotia from its previously documented occurrences near the southwestern tip of the province (from the 1950s), near Lunenburg (from the early 1990s), and Tor Bay (from the mid 2000s), an overall distance of approximately 500 km. In 2020 and 2021 we found attached F. serratus intertidally and subtidally at many sites along the Atlantic coastline, especially on the South Shore of Nova Scotia, and thalli in the wrack at many locations. In addition, we describe a new pattern of seaweed zonation for the northwestern Atlantic Ocean in which F. serratus has become a canopy-forming dominant species in large portions of the low to mid intertidal zone, where it can occupy from 20% to 40% of shore area, and dense populations extend to about 4 m below chart datum. This coastline of Nova Scotia has been identified as a regional hotspot for ocean warming, and adjacent annual air temperatures have risen over 1°C since the 1990s. We attribute the change in distribution and ecology of F. serratus to regional climate warming previously associated with major reductions in populations of kelp and sea urchins.
Evaluating salt marsh rhizosphere carbon stocks and arbuscular mycorrhizal colonization across a chronosequence in the Bay of Fundy, Nova Scotia
* Kendra Sampson, Saint Mary's University , Canada
Danika van Proosdij, Saint Mary's University
Jeremy Lundholm, Saint Mary's University
Allison Walker, Acadia University and Saint Mary's University
Salt marshes are essential ecosystems that stabilize coastlines while providing habitat and nursery for many invertebrates, juvenile fishes, and birds. Unfortunately, due to the development of agriculture, commercial land, and embanking/dyking, salt marshes are declining worldwide. Salt marshes can accumulate and store large amounts of carbon as “blue carbon”. Carbon is trapped from the atmosphere and rhizosphere by the salt marsh, which allows it to be utilized by salt marsh vegetation and their fungal associates. Recent studies have found that beneficial fungi form associations with salt marsh plant roots. Arbuscular mycorrhizal fungi (AMF) form these associations with approximately 80% of all land plants. AMF receive fixed carbon from their host plant, and in return, provide the plant with mineral nutrients and an increased surface area, which leads to greater carbon storage. We are investigating the role of AMF in helping salt marshes sequester carbon. We are examining the correlation between the amount of carbon and AMF colonization present in salt marsh plants. Additionally, we are analyzing the quantity of nitrogen, phosphorus, and salt present in the rhizosphere and exploring its effect on AMF colonization. Furthermore, we are evaluating how rhizosphere carbon stocks vary with vegetation types across a chronosequence of salt marshes in comparison with dykeland habitats fringing the Bay of Fundy, Canada. We have found high AMF colonization rates in Spartina pectinata roots with varying organic carbon rates. A further understanding of carbon stocks and mycorrhizal associations will increase our knowledge of their contributions to salt marsh restoration methods.
Implications of warming for conservation of endangered plants: a Nova Scotian case study
* Nicholas Hill, Fern Hill Institute of Plant Conservation, Canada
David Garbary, St. Francis Xavier University
Nova Scotia has warmed by about a degree centigrade between the two climate normal phases over the last 60 years. Taking these climate normal brackets as summaries of 30 years of weather data, the average annual air temperature increased by 0.8°C in 30 years. Period summaries and yearly averages of a whole region mask regional changes. The rate of change in some areas has been more rapid, e.g., a 2°C shift in temperature occurred on Brier Island from its cool normal for 1961–1990 to a “new normal” beginning in 2006. The impact of sudden warming on the endangered Arctic-alpine, Eastern Mountain Avens was not anticipated; “planning for and mitigating impacts of climate change on Eastern Mountain Avens” was ranked of low priority in the Action Plan (Environment Canada 2018) although the Recovery Strategy (2010) stated that threats (e.g., nutrient enrichment, interspecific competition, low water table, shrub growth) could be compounded by climate change. We discuss the challenges of adapt ive management of this endangered plant on a changing landscape and consider the tolerance limits of its physiology. Conservation concerns of imminent and active warming of a cold-origin, endangered species, however, are different from those that apply to warm origin, Atlantic Coastal Plain Flora. We contrast the cases of the Arctic–alpine Avens with the coastal plain Plymouth Gentian and Rockrose and look at the timing of impacts on key ecosystem processes (water tables, decomposition, ice scour, mineralization, transpiration, fire) and the vulnerabilities of growth and reproductive processes to climate change.
Experimental warming and drying reveals high stress resistance in jack pine versus reduced carbon uptake and growth in black and white spruce
* Catherine Léger-Beaulieu, Université Laval, Canada
Loïc D'organgeville, Faculty of Forestry & Environmental Management, University of New Brunswick
Daniel Houle, Ministère des forêts, de la faune et des parcs (MFFP) and Ouranos, Consortium sur le réchauffement climatique
Daniel Kneeshaw, 1 Département des sciences biologiques et Centre détude de la forêt, Université du Québec à Montréal
In boreal forest ecosystems, the projected increase in temperature and water stress is expected to modify many ecophysiological processes in trees, with amplified effects on seedlings. Moreover, tree species show different responses to climate change which suggests that acclimatation capabilities are species-specific. During our study, we subjected three boreal seedling species (Picea mariana, Picea glauca and Pinus banksiana) to four drought intensities (control, moderate, severe and low frequency respectively) nested in two temperature treatments (ambient versus projected temperature (+4°C)). Throughout the season, we observed and recorded their phenological and physiological responses. Our results show that drought treatments did not impact the physiological processes, growth, and phenology of jack pine. On the contrary, both spruces reduced their photosynthesis as well as their biomass production. In response to water stress, jack pine displays an anisohydric strategy while the spruces exhibit an isohydric strategy. Warming increased jack pine photosynthesis (19.5±0.18%), while it remained unchanged in both spruces. Temperature increases had contrasting effects on seedlings growth rate. Warming led to a higher growth rate for jack pine, while it remained unchanged for black spruce. White spruce growth rate decreased with warming. Also, both spruces grew earlier in the season with increasing temperature (13.3±0.14 days for white spruce and 15.5±0.13 days for black spruce). However, under ambient and elevated temperatures, jack pine is the faster growing species. Our results suggest that jack pine could be more tolerant to warming and drought stresses compared to black and white spruce
Exploring phytobiomes and bulk soils across biogeoclimatic zones in the coast, interior, and northern British Columbia
* Laura Super, University of British Columbia, Canada
Arsalan Mohammadi, University of British Columbia
Kristine Lin, University of British Columbia
Eully Ao, University of British Columbia
Monika Gorzelak, Agriculture and Agri-Food Canada
Robert Guy, University of British Columbia
Climate change will cause plants to migrate. Plant-associated organisms, including in soil food webs (e.g., fungi, bacteria, soil fauna), may move at different speeds creating novel phytobiomes. A phytobiome encompasses a plant, its associated micro- and macro-organisms, and the environment. Soil nematodes aid soil food web nutrient cycling and are bioindicators sensitive to different soils and abiotic conditions. We set out to compare the effects of planting interior Douglas-fir (Pseudotsuga menziesii var. glauca (Mayr) Franco) from two seedlots (southern adapted and northern adapted) on phytobiomes in replicate clear-cut sites (N = 3 per zone) located in coastal, interior, and northern British Columbia. After a year of growth, seedlings were randomly sampled for root and shoot biomass, rhizosphere organisms (i.e., nematode abundance, and DNA sequencing for ecological communities of prokaryotes and eukaryotes), and soil properties (N = 54 per seedlot). Bulk soils into which seedlings were not planted were also collected (N = 54). Plant biomass (shoot, root) was significantly lower at northern sites (P < 0.001). Overall, shoot biomass of northern adapted seedlings was greater than southern adapted (P = 0.026), but there were no significant differences within sites. Planted seedlings increased nematode densities relative to bulk soil (P = 0.004), with no seedlot effect. In conclusion, the addition of Douglas-fir seedlings increased the local abundance of soil nematodes on clear-cuts, regardless of the seed source. Forthcoming sequencing data will explore whether there are accompanying effects on nematode community composition and fungal and bacterial components of the phytobiome.
The question remains: are bryophytes tolerant to ultraviolet-B radiation?
* Javier Martínez-Abaigar, Universidad de La Rioja, Spain
María-Ángeles Del-Castillo-Alonso, Universidad de La Rioja
Rafael Tomás-Las-Heras, Universidad de La Rioja
Laura Monforte, Universidad de La Rioja
Pedro Lara, Universidad de La Rioja
Encarnación Núñez-Olivera, Universidad de La Rioja
Although being a minor component (around 0.25%) of solar radiation, the UV-B band (280-315 nm) is an important regulatory factor of plant physiology. However, in excess, UV-B can be harmful due to diverse types of damage. Almost 70 bryophytes (one hornwort, 16 liverworts, and 50 mosses) have been tested for UV-B tolerance in more than 100 studies, but the enormous diversity of conditions used for experimentation makes it difficult to generalize the results obtained. Thus, the question remains: are bryophytes tolerant to UV-B radiation? Aiming to help answer this question, we applied the same UV-B treatment to 64 bryophytes (two hornworts, 23 liverworts, and 39 mosses) collected in diverse mid-latitude environments, in the most extensive study to date on the subject. Using UV-B LEDs and cut-off filters, we applied 9 W m-2 UV-B (around 5-fold the peak irradiance received in a sunny day at mid-latitudes) to the samples for one hour under controlled conditions. UV-B tolerance was assessed using chlorophyll fluorescence variables. We confirmed that UV-B tolerance of bryophytes depends on the species considered, and is greatly influenced by the taxonomic group. Overall, mosses were more UV-B-tolerant than liverworts and hornworts, although a certain overlap between mosses and liverworts occurred. For example, Hookeria lucens, Mnium hornum, and Fontinalis squamosa were sensitive mosses, while Frullania tamarisci and Porella arboris-vitae were tolerant liverworts. UV-B tolerance was significantly correlated with the content of potentially protective UV-absorbing compounds, such as flavonoids, and with the sclerophylly of the shoots. Structural, physiological, and ecological aspects are discussed.
MOSSES AS BIOMONITOR: ATMOSPHERIC METAL LOAD OF PRE AND POST PANDEMIC PERIODS
* Dinesh Saxena, Bareilly College, Bareilly, UP India, India
Arti Saxena, University of waterloo
The steadily increasing trend of atmospheric metals requires continuous monitoring of the environment, their dispersion pattern, possible sources and their influence on ecosystem. For this mosses are preferred as ideal monitoring tools due to their wide-spread and potentials to survive in extreme harsh conditions. Instrumental monitoring is an expansive as it is associated with deployment instruments at number of sampling sites and manpower to run these. Bryophytes are wide in distribution and need no care for growth. Lack of root and conducting tissue rules out absorption of metals through substratum. Absence of cuticle helps their cell walls easy to assess for metals and to absorb metals over the entire surface Mosses have mechanisms to cope with the elevated concentrations of metals could be due to induction of metal binding protein (Zulema et al 2018 ). These mechanisms resulted in the ability of many bryophytes to survive and colonizes in metal rich areas. Result of analysis of moss transplants sample of the past 15 years till 2015 (pre-pandemic period) have shown an increasing trend of atmospheric metals. However, studies conducted during pandemic periods i.e. last week of March 2020, a nationwide lockdown was declared by the Government of India due to the pandemic, exhibited and alarming decrease in atmospheric metal load in moss samples harvested and analyzed for metals. A diminution in metal accumulation in moss samples measured during the lockdown period could be owing to minimal or no vehicular movement and halted operations of the factories and construction sites