scholarly journals Multiple stressors and disturbance effects on eelgrass and epifaunal macroinvertebrate assemblage structure

2021 ◽  
Vol 657 ◽  
pp. 93-108
Author(s):  
S Cimon ◽  
A Deslauriers ◽  
M Cusson
Keyword(s):  
Nutrient Enrichment ◽  
Field Experiments ◽  
Multiple Stressors ◽  
Shoot Density ◽  
Assemblage Structure ◽  
Interactive Effects ◽  
Anthropogenic Pressure ◽  
Ecosystem Structure ◽  
Density Reduction ◽  
External Forces

Multiple forms of environmental change and anthropogenic pressure co-occur in coastal marine ecosystems. These external forces affect ecosystem structure, functioning, and, eventually, services to humans. Studies that include more than 2 simultaneous stressors are still needed to understand potential interactions among multiple stressors. We evaluated single and interactive effects of density reduction of Zostera marina L. (a habitat-forming species), shading, and sediment nutrient enrichment on the response of Z. marina and its associated epifauna over 10 wk. Shading had the greatest effect on reducing the eelgrass relative leaf elongation rate (RLE), non-structural carbohydrate reserves, and eelgrass shoot density. A reduced eelgrass density sustained higher epifaunal densities and increased the eelgrass RLE. Sediment nutrient enrichment increased eelgrass shoot density but decreased epifaunal richness, diversity, and total abundance. Our disturbance and pair of stressors differed in their influence on diversity measures, but all affected assemblage structure. Most of the changes to the epifaunal assemblage and diversity likely occurred due to altered habitat availability and epiphytic algae load. We observed additive, antagonistic, and negatively synergistic interactions among our treatments, while most of the cumulative effects showed dominance by one stressor over another. Our results highlight the importance of field experiments that are based on multiple disturbances and stressors to determine their interaction type on communities.

scholarly journals Interactive effects of climate and nutrient enrichment on patterns of herbivory by different feeding guilds in mangrove forests

2017 ◽  
Vol 26 (11) ◽  
pp. 1326-1338 ◽  
Author(s):  
Ilka C. Feller ◽  
Marilyn C. Ball ◽  
Joanne I. Ellis ◽  
Catherine E. Lovelock ◽  
Ruth Reef
Keyword(s):  
Nutrient Enrichment ◽  
Interactive Effects ◽  
Feeding Guilds ◽  
Mangrove Forests

scholarly journals Nitrogen enrichment offsets direct negative effects of ocean acidification on a reef-building crustose coralline alga

2018 ◽  
Vol 14 (7) ◽  
pp. 20180371 ◽  
Author(s):  
Maggie D. Johnson ◽  
Robert C. Carpenter
Keyword(s):  
Ocean Acidification ◽  
Nutrient Enrichment ◽  
Multiple Stressors ◽  
Crustose Coralline Alga ◽  
Nitrogen Enrichment ◽  
Coralline Alga ◽  
Ambient Conditions ◽  
Negative Effects ◽  
Near Shore ◽  
Near Future

Ocean acidification (OA) and nutrient enrichment threaten the persistence of near shore ecosystems, yet little is known about their combined effects on marine organisms. Here, we show that a threefold increase in nitrogen concentrations, simulating enrichment due to coastal eutrophication or consumer excretions, offset the direct negative effects of near-future OA on calcification and photophysiology of the reef-building crustose coralline alga, Porolithon onkodes . Projected near-future pCO 2 levels (approx. 850 µatm) decreased calcification by 30% relative to ambient conditions. Conversely, nitrogen enrichment (nitrate + nitrite and ammonium) increased calcification by 90–130% in ambient and high pCO 2 treatments, respectively. pCO 2 and nitrogen enrichment interactively affected instantaneous photophysiology, with highest relative electron transport rates under high pCO 2 and high nitrogen. Nitrogen enrichment alone increased concentrations of the photosynthetic pigments chlorophyll a , phycocyanin and phycoerythrin by approximately 80–450%, regardless of pCO 2 . These results demonstrate that nutrient enrichment can mediate direct organismal responses to OA. In natural systems, however, such direct benefits may be counteracted by simultaneous increases in negative indirect effects, such as heightened competition. Experiments exploring the effects of multiple stressors are increasingly becoming important for improving our ability to understand the ramifications of local and global change stressors in near shore ecosystems.

Can Indirect Herbicide Exposure Modify the Response of the Colorado Potato Beetle to an Organophosphate Insecticide?

2019 ◽  
Vol 112 (5) ◽  
pp. 2316-2323 ◽  
Author(s):  
Aigi Margus ◽  
Miia Rainio ◽  
Leena Lindström
Keyword(s):  
Colorado Potato Beetle ◽  
Target Genes ◽  
Multiple Stressors ◽  
Synergistic Effects ◽  
Oxidative Status ◽  
Interactive Effects ◽  
Invasive Pest ◽  
Lipid Hydroperoxides ◽  
Organophosphate Insecticide ◽  
Potato Beetle

AbstractOrganisms live in complex multivariate environments. In agroecosystems, this complexity is often human-induced as pest individuals can be exposed to many xenobiotics simultaneously. Predicting the effects of multiple stressors can be problematic, as two or more stressors can have interactive effects. Our objective was to investigate whether indirect glyphosate-based herbicide (GBH) exposure of the host plant has interactive effects in combination with an insecticide (azinphos-methyl) on an invasive pest Colorado potato beetle (Leptinotarsa decemlineata Say). We tested the effects of GBH and insecticide on the survival, insecticide target genes expression (acetylcholinesterase genes) and oxidative status biomarkers (glutathione S-transferase [GST], glucose-6-phosphate dehydrogenase [G6PDH], glutathione reductase homolog [GR], glutathione peroxidase homolog [GPx], total glutathione [totGSH], glutathione reduced-oxidized [GSH: GSSG], catalase [CAT], superoxide dismutase [SOD], lipid hydroperoxides). We found that exposure to indirect GBH has no single or interactive effects in combination with the insecticide on larval survival. However, prior exposure to GBH inhibits Ldace1 gene expression by 0.55-fold, which is the target site for the organophosphate and carbamate insecticides. This difference disappears when individuals are exposed to both GBH and insecticide, suggesting an antagonistic effect. On the other hand, oxidative status biomarker scores (PCAs of GPx, GR, and CAT) were decreased when exposed to both stressors, indicating a synergistic effect. Overall, we found that indirect GBH exposure can have both antagonistic and synergistic effects in combination with an insecticide, which should be considered when aiming for an ecologically relevant risk assessment of multiple human-induced stressors.

scholarly journals Seagrass of Vasiliko Bay, Eastern Mediterranean: Lost Cause or Priority Conservation Habitat?

2020 ◽  
Vol 8 (9) ◽  
pp. 717
Author(s):  
Demetris Kletou ◽  
Periklis Kleitou ◽  
Ioannis Savva ◽  
Martin J. Attrill ◽  
Stephanos Charalambous ◽  
...  
Keyword(s):  
Surface Area ◽  
Multiple Stressors ◽  
Eastern Mediterranean ◽  
Ecological Status ◽  
Fish Farming ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Fish Farms ◽  
Leaf Surface Area ◽  
Marine Fish Farming

Mediterranean coasts are affected by multiple mounting pressures. In Cyprus, marine fish farming has grown rapidly in the past decade and is concentrated in the west side of Vasiliko Bay. The east coast of this bay has ports, a power station, a desalination unit, a cement factory, a major new oil terminal, and gas storage facilities. The bay is earmarked to create the largest hydrocarbon processing, storing, and transport facility in the region. Here, we assess the status of Posidonia oceanica habitat in an understudied region at the upper thermal, and eastern limit, of this Mediterranean endemic seagrass. An extensive ancient seagrass meadow was revealed, covering about 200 ha across 10 km of coastline, over soft substrata at ca 10–30 m depth, and over hard substrata at ca 0–6 m depth. Seagrass shoot density and leaf surface area decreased, both with increasing depth and with proximity to industrial developments; part of the meadow had been destroyed by dredging to build a jetty. Close to fish farms the seagrass had higher epiphytic biomass as well as lower leaf number, mass, and surface area, all of which indicate adverse effects of eutrophication and increased turbidity. Despite these multiple stressors, most of the meadow was in good ecological status, with some of the highest shoot densities ever reported. Furthermore, iconic species like sea turtles, monk seals, and dolphins were seen during sampling. Posidonia oceanica meadows off Cyprus are among the most valuable in the Mediterranean due to their tolerance of high seawater temperatures. Managers of future coastal developments in the region will need to adhere to European legislation and international conventions designed to secure the socioeconomic benefits of seagrass beds.

scholarly journals Fisheries impacts on lake ecosystem structure in the context of a changing climate and trophic state

2017 ◽  
Author(s):  
Tiina Nõges ◽  
Orlane Anneville ◽  
Jean Guillard ◽  
Juta Haberman ◽  
Ain Järvalt ◽  
...  
Keyword(s):  
Water Quality ◽  
Trophic State ◽  
Scale Effects ◽  
Trophic Levels ◽  
Interactive Effects ◽  
Phosphorus Loading ◽  
Lake Ecosystem ◽  
Ecosystem Structure ◽  
Top Down ◽  
Lake Basins

<p>Through cascading effects within lake food webs, commercial and recreational fisheries may indirectly affect the abundances of organisms at lower trophic levels, such as phytoplankton, even if they are not directly consumed. So far, interactive effects of fisheries, changing trophic state and climate upon lake ecosystems have been largely overlooked. Here we analyse case studies from five European lake basins of differing trophic states (Lake Võrtsjärv, two basins of Windermere, Lake Geneva and Lake Maggiore) with long-term limnological and fisheries data. Decreasing phosphorus concentrations (re-oligotrophication) and increasing water temperatures have been reported in all five lake basins, while phytoplankton concentration has decreased only slightly or even increased in some cases. To examine possible ecosystem-scale effects of fisheries, we analysed correlations between fish and fisheries data, and other food web components and environmental factors. Re-oligotrophication over different ranges of the trophic scale induced different fish responsesIn the deeper lakes Geneva and Maggiore, we found a stronger link between phytoplankton and planktivorous fish and thus a more important cascading top-down effect than in other lakes. This connection makes careful ecosystem-based fisheries management extremely important for maintaining high water quality in such systems. We also demonstrated that increasing water temperature might favour piscivores at low phosphorus loading, but suppresses them at high phosphorus loading and might thus either enhance or diminish the cascading top-down control over phytoplankton with strong implications for water quality.</p>

scholarly journals Invasion-mediated effects on marine trophic interactions in a changing climate: positive feedbacks favour kelp persistence

2019 ◽  
Vol 286 (1899) ◽  
pp. 20182866 ◽  
Author(s):  
Ricardo J. Miranda ◽  
Melinda A. Coleman ◽  
Alejandro Tagliafico ◽  
Maria S. Rangel ◽  
Lea T. Mamo ◽  
...  
Keyword(s):  
Climate Change ◽  
Trophic Interactions ◽  
Multiple Stressors ◽  
Grazing Intensity ◽  
Ocean Warming ◽  
Interactive Effects ◽  
Ecological Change ◽  
Climate Change Scenarios ◽  
Ecological Consequences ◽  
Management Actions

The interactive effects of ocean warming and invasive species are complex and remain a source of uncertainty for projecting future ecological change. Climate-mediated change to trophic interactions can have pervasive ecological consequences, but the role of invasion in mediating trophic effects is largely unstudied. Using manipulative experiments in replicated outdoor mesocosms, we reveal how near-future ocean warming and macrophyte invasion scenarios interactively impact gastropod grazing intensity and preference for consumption of foundation macroalgae ( Ecklonia radiata and Sargassum vestitum ). Elevated water temperature increased the consumption of both macroalgae through greater grazing intensity. Given the documented decline of kelp ( E. radiata ) growth at higher water temperatures, enhanced grazing could contribute to the shift from kelp-dominated to Sargassum -dominated reefs that is occurring at the low-latitude margins of kelp distribution. However, the presence of a native invader ( Caulerpa filiformis ) was related to low consumption by the herbivores on dominant kelp at warmer temperatures. Thus, antagonistic effects between climate change and a range expanding species can favour kelp persistence in a warmer future. Introduction of species should, therefore, not automatically be considered unfavourable under climate change scenarios. Climatic changes are increasing the need for effective management actions to address the interactive effects of multiple stressors and their ecological consequences, rather than single threats in isolation.

scholarly journals Three-dimensional printing, muscles, and skeleton: mechanical functions of living wood

2019 ◽  
Vol 70 (14) ◽  
pp. 3453-3466 ◽  
Author(s):  
Bernard Thibaut
Keyword(s):  
Additive Manufacturing ◽  
Field Experiments ◽  
Secondary Growth ◽  
Three Dimensional ◽  
Wood Properties ◽  
Force Generation ◽  
Three Dimensional Printing ◽  
Pipe System ◽  
External Forces ◽  
Dimensional Printing

AbstractWood is well defined as an engineering material. However, living wood in the tree is often regarded only as a passive skeleton consisting of a sophisticated pipe system for the ascent of sap and a tree-like structure made of a complex material to resist external forces. There are two other active key roles of living wood in the field of biomechanics: (i) additive manufacturing of the whole structure by cell division and expansion, and (ii) a ‘muscle’ function of living fibres or tracheids generating forces at the sapwood periphery. The living skeleton representing most of the sapwood is a mere accumulation of dead tracheids and libriform fibres after their programmed cell death. It keeps a record of the two active roles of living wood in its structure, chemical composition, and state of residual stresses. Models and field experiments define four biomechanical traits based on stem geometry and parameters of wood properties resulting from additive manufacturing and force generation. Geometric parameters resulting from primary and secondary growth play the larger role. Passive wood properties are only secondary parameters, while dissymmetric force generation is key for movement, posture control, and tree reshaping after accidents.

Sign in / Sign up

Export Citation Format

Share Document