Influence of nutrients enrichment on ecosystem functioning in a subpolar seagrass meadow

2020 ◽  
Author(s):  
Ludovic Pascal ◽  
Gwénaëlle Chaillou ◽  
Pascal Bernatchez ◽  
Christian Nozais ◽  
Philippe Archambault
Keyword(s):  
Nutrient Enrichment ◽  
Ecosystem Functioning ◽  
Anthropogenic Activities ◽  
Growing Season ◽  
Benthic Fluxes ◽  
Seagrass Meadows ◽  
Time Period ◽  
Mesocosm Experiments ◽  
Functional Consequences ◽  
Summer Time

<p>Seagrass meadows are among the most productive ecosystems in the world: they store a large amount of carbon and host highly diverse macrobenthic communities. They also play a key role in biogeochemistry at the sediment-water interface. The light requirements of seagrasses limit their development to shallow coastal areas where they are facing various natural and anthropogenic disturbances, which has induced a global loss of these ecosystems over the last decades. Nutrient enrichment of coastal waters, resulting from anthropogenic activities is one of the leading causes of this decline. Subpolar seagrass meadows present a strong seasonal dynamic, with a long winter when seagrasses rely on carbon reserves that they build up during the short growing season (limited to two to three months during summer time). Hence, it has been hypothesized that the effects of nutrient enrichment on seagrass ecosystem functioning depend on seasonal dynamics. In this study, we performed a series of mesocosm experiments over a month period to investigate the effects of the timing, duration and intensity of disturbance on macrofauna bioturbation, oxygen and nutrients porewater concentration profiles and benthic fluxes using three levels (including control) of realistic nutrient enrichments at the beginning (June) and at the end (August) of the growing season. In May, effects of intermediate level of nutrient enrichment were only visible on total oxygen uptake by the sediment at day 30 of disturbance while it affected oxygen and nutrients benthic fluxes at day 15 in August. The highest level of nutrient enrichment affected oxygen and nutrients benthic fluxes in May and August. Overall, our results highlight the importance of considering the time (period and duration) in the assessment of the functional consequences of disturbances.</p>

Assessing the impact of exceptional inter-annual climatic variability on rates of net ecosystem carbon dioxide exchange at Clara bog.

2021 ◽  
Author(s):  
Matthew Saunders ◽  
Ruchita Ingle ◽  
Shane Regan
Keyword(s):  
Water Table ◽  
Elevated Temperatures ◽  
Ecosystem Respiration ◽  
Anthropogenic Activities ◽  
Climatic Variability ◽  
Growing Season ◽  
Carbon Dioxide Exchange ◽  
Mean Annual Temperature ◽  
Monitoring Networks ◽  
The Impact

<p>Peatland ecosystems are integral to the mitigation of climate change as they represent significant terrestrial carbon sinks. In Ireland, peatlands cover ~20% of the land area but hold up to 75% of the soil organic carbon stock however many of these ecosystems (~85% of the total area) have been degraded due to anthropogenic activities such as agriculture, forestry and extraction for horticulture or energy. Furthermore, the carbon stocks that remain in these systems are vulnerable to inter-annual variation in climate, such as changes in precipitation and temperature, which can alter the hydrological status of these systems leading to changes in key biogeochemical processes and carbon and greenhouse gas exchange.  During 2018 exceptional drought and heatwave conditions were reported across Northwestern Europe, where reductions in precipitation coupled with elevated temperatures were observed. Exceptional inter-annual climatic variability was also observed at Clara bog, a near natural raised bog in the Irish midlands when data from 2018 and 2019 were compared. Precipitation in 2018 was ~300 mm lower than 2019 while the average mean annual temperature was 0.5°C higher. The reduction in precipitation, particularly during the growing season in 2018, consistently lowered the water table where ~150 consecutive days where the water table was >5cm below the surface of the bog were observed at the central ecotope location. The differing hydrological conditions between years resulted in the study area, as determined by the flux footprint of the eddy covariance tower, acting as a net source of carbon of 53.5 g C m<sup>-2</sup> in 2018 and a net sink of 125.2 g C m<sup>-2</sup> in 2019. The differences in the carbon dynamics between years were primarily driven by enhanced ecosystem respiration (R<sub>eco</sub>) and lower rates of Gross Primary Productivity (GPP) in the drier year, where the maximum monthly ratio of GPP:R<sub>eco</sub> during the growing season was 0.96 g C m<sup>-2</sup> month in 2018 and 1.14 g C m<sup>-2</sup> month in 2019. This study highlights both the vulnerability and resilience of these ecosystems to exceptional inter-annual climatic variability and emphasises the need for long-term monitoring networks to enhance our understanding of the impacts of these events when they occur.</p>

scholarly journals Plant traits are poor predictors of long-term ecosystem functioning

2019 ◽  
Author(s):  
Fons van der Plas ◽  
Thomas Schröder-Georgi ◽  
Alexandra Weigelt ◽  
Kathryn Barry ◽  
Sebastian Meyer ◽  
...  
Keyword(s):  
Plant Species ◽  
Ecosystem Functioning ◽  
Plant Traits ◽  
Vascular Plant ◽  
Plant Performance ◽  
Ecosystem Functions ◽  
Average Percentage ◽  
Functional Consequences ◽  
Small Set

ABSTRACTEarth is home to over 350,000 vascular plant species1 that differ in their traits in innumerable ways. Yet, a handful of functional traits can help explaining major differences among species in photosynthetic rate, growth rate, reproductive output and other aspects of plant performance2–6. A key challenge, coined “the Holy Grail” in ecology, is to upscale this understanding in order to predict how natural or anthropogenically driven changes in the identity and diversity of co-occurring plant species drive the functioning of ecosystems7, 8. Here, we analyze the extent to which 42 different ecosystem functions can be predicted by 41 plant traits in 78 experimentally manipulated grassland plots over 10 years. Despite the unprecedented number of traits analyzed, the average percentage of variation in ecosystem functioning that they jointly explained was only moderate (32.6%) within individual years, and even much lower (12.7%) across years. Most other studies linking ecosystem functioning to plant traits analyzed no more than six traits, and when including either only six random or the six most frequently studied traits in our analysis, the average percentage of explained variation in across-year ecosystem functioning dropped to 4.8%. Furthermore, different ecosystem functions were driven by different traits, with on average only 12.2% overlap in significant predictors. Thus, we did not find evidence for the existence of a small set of key traits able to explain variation in multiple ecosystem functions across years. Our results therefore suggest that there are strong limits in the extent to which we can predict the long-term functional consequences of the ongoing, rapid changes in the composition and diversity of plant communities that humanity is currently facing.

scholarly journals The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

AMBIO ◽  
2019 ◽  
Vol 49 (7) ◽  
pp. 1257-1267 ◽  
Author(s):  
Benjamin L. Jones ◽  
Richard K. F. Unsworth
Keyword(s):  
Ecosystem Functioning ◽  
Trophic Structure ◽  
Bed Nets ◽  
Great Effort ◽  
Mosquito Net ◽  
Seagrass Meadows ◽  
Mosquito Nets ◽  
Biomass Removal ◽  
Global Health Issue ◽  
Commercially Important

Abstract Malaria is a serious global health issue, with around 200 million cases per year. As such, great effort has been put into the mass distribution of bed nets as a means of prophylaxis within Africa. Distributed mosquito nets are intended to be used for malaria protection, yet increasing evidence suggests that fishing is a primary use for these nets, providing fresh concerns for already stressed coastal ecosystems. While research documents the scale of mosquito net fisheries globally, no quantitative analysis of their landings exists. The effects of these fisheries on the wider ecosystem assemblages have not previously been examined. In this study, we present the first detailed analysis of the sustainability of these fisheries by examining the diversity, age class, trophic structure and magnitude of biomass removal. Dragnet landings, one of two gear types in which mosquito nets can be utilised, were recorded across ten sites in northern Mozambique where the use of Mosquito nets for fishing is common. Our results indicate a substantial removal of juveniles from coastal seagrass meadows, many of which are commercially important in the region or play important ecological roles. We conclude that the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning.

scholarly journals Temporal Patterns of Sporulation Potential of Phomopsis viticola on Infected Grape Shoots, Canes, and Rachises

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1297-1302 ◽  
Author(s):  
D. J. Anco ◽  
L. V. Madden ◽  
M. A. Ellis
Keyword(s):  
Leaf Spot ◽  
Temporal Pattern ◽  
Growing Season ◽  
First Year ◽  
Bud Break ◽  
Optimal Conditions ◽  
Phomopsis Viticola ◽  
Time Period ◽  
Dormant Season ◽  
Vitis Spp

Phomopsis cane and leaf spot on Vitis spp. (grape) is currently understood to be monocyclic, with primary inoculum only being produced early in the growing season. However, of the few published studies pertaining to sporulation of Phomopsis viticola, none specifically examined rachises, and none were designed to determine when infected tissues become capable of sporulation. The objective of these studies was to determine when grape shoots, canes, and rachises infected with P. viticola develop the capacity to sporulate, and to determine the time period during which those tissues remain capable of sporulation. Starting in 2009 and 2010, infected first-year shoots and rachises were collected biweekly throughout the growing season, into the dormant season, and into the following growing season. Tissues were collected from ‘Catawba,’ ‘Concord,’ and ‘Reliance’ vineyards. Samples were observed for sporulation after 48 h of incubation in a moist chamber at 23°C; the magnitude of the conidia production under these optimal conditions was considered the sporulation potential. For infections that occurred in 2009 and 2010, the production of conidia was not observed until after harvest. In the year following infection, sporulation potential was found from about bud break until shortly after the end of bloom. There was a generally consistent temporal pattern to relative sporulation potential across sampled vineyards, years, and grape tissues (rachises and canes), described by a modified β model, with peak sporulation potential occurring around 16 May. These results confirmed that Phomopsis cane and leaf spot is a monocyclic disease and support control recommendations for use of fungicides in spring.

scholarly journals Temperature-related Variables Associated with Yield of ‘Kerman’ Pistachio in the San Joaquin Valley of California

HortScience ◽  
2017 ◽  
Vol 52 (4) ◽  
pp. 598-605 ◽  
Author(s):  
Craig E. Kallsen
Keyword(s):  
Crop Yield ◽  
Air Temperature ◽  
Growing Season ◽  
San Joaquin Valley ◽  
Efficient Allocation ◽  
Time Period ◽  
Processing Facility ◽  
Time Periods ◽  
Advance Knowledge ◽  
Facility Capacity

Information on how annual pistachio yield is affected by air temperature (Ta) during the winter and growing season is lacking. Timely advance knowledge of the magnitude of the yield of the California pistachio harvest would be beneficial for the pistachio industry for efficient allocation of harvest and postharvest resources, such as personnel, harvesting machinery, trucks, processing facility capacity, crop storage facilities, and for making marketing decisions. The objective of this study was to identify parameters, especially Ta variables and time periods, calculated from Ta data during the previous fall, winter, spring, and summer, that were associated most closely with fall nut-crop yield. The premise of this study was that sequential, historical yield records could be regressed against a number of Ta-derived variables to identify Ta thresholds and accumulations that have value in explaining past and predicting subsequent nut yield. Of the 27 regression variables examined in this study, the following, which were all negatively correlated with subsequent yield, explained the greatest proportion of the variability present in predicting yield of ‘Kerman’ pistachio: yield of the previous-year harvest, hourly Ta accumulations above 26.7 or 29.4 °C from the time period between 20 Mar. and 25 Apr., hourly Ta accumulations below 7.2 °C from 15 Nov. to 15 Feb., and hourly Ta accumulations above 18.3 °C from 15 Nov. to 15 Feb.

The exergy of a phase shift: Ecosystem functioning loss in seagrass meadows of the Mediterranean Sea

2015 ◽  
Vol 156 ◽  
pp. 186-194 ◽  
Author(s):  
Monica Montefalcone ◽  
Paolo Vassallo ◽  
Giulia Gatti ◽  
Valeriano Parravicini ◽  
Chiara Paoli ◽  
...  
Keyword(s):  
Phase Shift ◽  
Mediterranean Sea ◽  
Ecosystem Functioning ◽  
Seagrass Meadows ◽  
The Mediterranean

Subnivean embryo development in the alpine herb Caltha leptosepala (Ranunculaceae)

2001 ◽  
Vol 79 (5) ◽  
pp. 635-642 ◽  
Author(s):  
Tara A Forbis ◽  
Pamela K Diggle
Keyword(s):  
Embryo Development ◽  
Low Temperatures ◽  
Histological Analysis ◽  
Growing Season ◽  
Perennial Herb ◽  
Wet Meadow ◽  
Morphophysiological Dormancy ◽  
Time Period ◽  
Embryo Dormancy ◽  
Further Development

Caltha leptosepala D.C. (Ranunculaceae) is a perennial herb of alpine wet meadows. Seeds of this species have morphophysiological dormancy; they contain a rudimentary embryo that must undergo further development prior to germination. The embryo itself is also dormant and requires a physiological cue for resumption of development. We ask how C. leptosepala can break embryo dormancy and complete embryo development, germination, and seedling growth under the constraint of the extremely short alpine wet meadow growing season. Seeds were stratified at 2.5°C and collected at regular intervals for germination trials and histological analysis. At dispersal, the embryo occupies approximately 7% of the length of the seed and is dormant. Embryo development resumes within 1 month of stratification. Embryos grow to fill the seed over a 4- to 7-month period. Germination rates are positively correlated with stratification time and reach 50% at 4 months and 70% at 7 months. Because embryo development requires a time period longer than the snow-free period prior to germination in the alpine wet meadow, we conclude that embryo development in C. leptosepala takes place beneath alpine snowbanks. Morphophysiological dormancy in Caltha is not uniquely derived, but the ability of Caltha embryos to develop and germinate at low temperatures may be an adaptation to their environment.Key words: alpine, rudimentary embryo, Ranunculaceae, seed, dormancy, germination.

A proposed decision support tool for prioritising conservation planning of Southeast Asian seagrass meadows: combined approaches based on ecosystem services and vulnerability analyses

2018 ◽  
Vol 61 (3) ◽  
pp. 305-320 ◽  
Author(s):  
Yi Mei Tan ◽  
Justine E. Saunders ◽  
Siti Maryam Yaakub
Keyword(s):  
Ecosystem Services ◽  
Southeast Asia ◽  
Cultural Values ◽  
Conservation Planning ◽  
Anthropogenic Activities ◽  
Impact Resistance ◽  
Conservation Priority ◽  
Support Tool ◽  
Seagrass Meadows ◽  
Anthropogenic Threats

AbstractSeagrass habitats provide a range of goods and benefits to coastal communities by supporting ecosystem functioning, food provisioning, and cultural values. However, they are at risk worldwide from anthropogenic activities, climate change impacts and limited resources, which hamper efforts to protect them. Effective conservation planning requires prioritisation of sites based on multiple factors, including their relative value and vulnerability (VU). The current study examines the efficacy of combining two well-established approaches – ecosystem service assessments and habitat VU analyses – to test a method for determining conservation priority for selected seagrass meadows in Southeast Asia. Seven seagrass meadows around Southeast Asia were selected and scored by the authors based on (1) the cumulative contribution of 12 ecosystem services (ES) and the condition of the meadows, (2) VU from 16 anthropogenic threats, which were each ranked against five factors (spatial scale, frequency, functional impact, resistance and recovery time) and (3) the combination of the two approaches to create a single numerical index. Prioritisation of sites differed when meadows were scored solely for the ES they provide, compared to how vulnerable they are to anthropogenic threats. The new combined analysis brought the two metrics together to give conservation priority to sites where management intervention will yield maximum conservation benefits from conservation effort, and resulted in the prioritisation of three sites: Barrang Lompo (Indonesia), Cape Bolinao (Philippines) and Beting Tanjung Kupang (Malaysia). This method is easy to use and does not require great technical expertise. It is also auditable, allowing for clear and transparent understanding of decision-making process.

scholarly journals Biogenic structures in the Arctic: an ecosystem functioning hotspot?

2018 ◽  
Author(s):  
Marie Pierrejean ◽  
Philippe Archambault ◽  
Barbara Neves ◽  
Evan Edinger ◽  
Christian Nozais
Keyword(s):  
Ecosystem Functioning ◽  
Cold Water ◽  
Sediment Cores ◽  
Three Dimensional ◽  
Ammonium Phosphate ◽  
The Arctic ◽  
Benthic Fluxes ◽  
Bare Sediment ◽  
Biogenic Structures ◽  
Associated Species

In deep-sea environments, resources availability and habitat complexity drive the distribution of benthic organisms. Biogenic structures such as cold-water corals and sponges create a three-dimensional habitat that facilitate sediment and resources accumulation and therefore show a high abundance of the associated species compared to bare sediments. However, the functions of these biodiversity hotspots in the ecosystem functioning are still poorly known. In this study, we addressed three main questions: 1) do benthic fluxes vary according to their position within patches and bare sediment? 2) are infaunal communities similar in biogenic structure and bare sediment patches? and finally, 3) which variables explain benthic fluxes in these patches? Infaunal communities and benthic fluxes were examined in Arctic regions presenting two types of biogenic structures: corals (Keratoisis sp.) and arborescent sponges. To compare ecosystem functioning between the biogenic structure versus bare sediment patches, sediment cores were collected to quantify benthic fluxes (nitrate, nitrite, ammonium, phosphate and silicate) and the diversity, abundance and composition of infauna. Multivariate analyses suggested that biogenic structure and bare sediment patches exhibited different infaunal assemblage and a spatial pattern for the benthic fluxes even with a distance of 100 m between the type of patches.

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