Potential impacts of climate interventions on marine ecosystems

The productivity and survival of algae are strongly affected by their physiological and biochemical processes, as well as biotic and abiotic factors in the environment. In recent years, global climate change such as increased temperature and elevated ultraviolet radiation (UVR) due to ozone depletion has huge impact on organisms particularly the ones in the marine ecosystem. It has been demonstrated that the global temperature increased steadily over the last decade, with an average of 0.74°C. In the coming years, climate model projections summarized by the Intergovernmental Panel of Climate Change (IPCC) indicate that average global surface temperature will likely rise a further 0.5 to 1.6°C by 2030, and rising to 1.1 to 6.4°C by 2100. As algae serve as the primary producer of food chain in both marine and terrestrial ecosystems, it is of great significance to understand the impact of temperature change on their physiological and biochemical processes. This review provides the information on how algae respond to temperature change based on their growth, biochemical composition and fatty acid composition.

<p>Changes in the distributions of organisms not only alter community composition and food web structure, but also can initiate important changes at the ecosystem level. Understanding the interactions between biotic and abiotic factors affecting species’ distribution patterns in temperate habitats is important for predicting responses to future environmental change. Sponges are important members of temperate rocky reefs assemblages that are influenced by a number of abiotic factors including water movement, light regime, inclination and stability of the substratum, as well as complex ecological interactions. The aim of this thesis was to investigate the interactions between sponges and macroalgae on shallow-water rocky reefs of Wellington, New Zealand, assessing if the distribution patterns of sponges are independent of algal populations. I used a combination of surveys, and manipulative field and laboratory experiments to explore the existence of interactions (positive or negative) between sponges and macroalgae and also to explore the effect of environmental factors on the distribution and abundance of temperate sponges. My first objective was to determine if the spatial distribution patterns of sponges are independent of macroalgae distribution and abundance at different sites on the Wellington south coast (Chapter 2). The results showed that abundance of most sponge species were strongly correlated with inclination, which supports previous studies in the northern hemisphere suggesting that sponge abundance and algal abundance are negatively correlated. In contrast, only a few sponge species were positively correlated with algal abundance. I then explored the positive interactions occurring between some sponges species and the presence of canopy-forming algae (Chapter 3). Results from this chapter suggest the canopy of Ecklonia radiata facilitates the existence of some sponge species such as Crella incrustans on vertical rocky walls. The removal of Ecklonia canopy led to a community dominated by turf algae, which corresponded with a decrease in sponge abundance and richness. My results suggest that the Ecklonia canopy facilitates the presence of some sponge species and allows their coexistence with turf algae underneath the canopy and also by altering immediate physical factors that may be detrimental for some sponge species. To further explore the existence of sponges and understory algae, I used an experimental approach (Chapter 4) to investigate the effect of the brown alga Zonaria turneriana on Leucetta sp. and also mechanisms involved in the interactions. However results from this chapter provided no evidence to support previous hypotheses that understory algae negatively affect sponges. In the last data chapter (Chapter 5), I studied sponges inhabiting different habitats in order to test if environmental variation affects the abundance and diversity of microorganisms, hence having the potential to affect the distribution and abundance of these species The stability observed in bacterial communities among specimens occupying different habitats suggests that environmental variation occurring in those habitats does not affect the stability of the community, and hence most likely does not radically alter the metabolism of these sponges. Although environmental factors such as light and sediment may have an effect on early sponge stages, other environmental (e.g. nutrients, temperature, wave action) and biotic factors, are more likely to influence the growth, survival and distribution of sponges on temperate rocky reefs. In summary, temperate sponge assemblages are strongly influenced by interactions between a number of abiotic and biotic factors. The outcomes of the ecological interactions are controlled by environment (e.g. influence of inclination on competition between sponges and understory algae) and at the same time, biological interactions (e.g. facilitation) can moderate the influence of abiotic factors such as light, sedimentation and wave action, thus facilitating the coexistence between sponge and macroalgae underneath the Ecklonia canopy. My thesis makes a significant contribution to our knowledge of temperate subtidal ecology, in terms of the effects of biotic and abiotic factors on sponge assemblages and also improves our knowledge of temperate patterns of sponge and macroalgal interactions. Finally, my thesis highlights the importance of small-scale environmental variation in influencing the structure and diversity of sponge assemblages and also increase our understanding of temperate rocky reefs sponges, especially on the less studied sponge assemblages occurring in Ecklonia stands on vertical rocky walls.</p>

Abiotic and biotic drivers of aboveground biomass in semi-steppe rangelands

The paper contributes to the Sustainable Development Goals (SDGs) targeting Life Below Water by introducing user-friendly modeling approaches. It delves into the impact of abiotic factors on the first two trophic levels within the marine ecosystem, both naturally and due to human influence. Specifically, the study examines the connections between environmental parameters (e.g., temperature, salinity, nutrients) and plankton along the Romanian Black Sea coast during the warm season over a decade. The research develops models to forecast zooplankton proliferation using machine learning (ML) algorithms and gathered data. Water temperature significantly affects copepods and “other groups” of zooplankton densities during the warm season. Conversely, no discernible impact is observed on dinoflagellate Noctiluca scintillans blooms. Salinity fluctuations notably influence typical phytoplankton proliferation, with phosphate concentrations primarily driving widespread blooms. The study explores two scenarios for forecasting zooplankton growth: Business as Usual, predicting modest increases in temperature, salinity, and constant nutrient levels, and the Mild scenario, projecting substantial temperature and salinity increases alongside significant nutrient decrease by 2042. The findings underscore high densities of Noctiluca scintillans under both scenarios, particularly pronounced in the second scenario, surpassing the first by around 70%. These findings, indicative of a eutrophic ecosystem, underscore the potential implications of altered abiotic factors on ecosystem health, aligning with SDGs focused on Life Below Water.

BackgroundOncomelania snails serve as the sole intermediate host for Schistosoma japonicum, one of the most important neglected tropical diseases in the world. Afforestation suppression of the Oncomelania hupensis snail has been a long-term effective national strategy to decrease snail density in China. Many previous studies have made clear that vegetation (biotic factors) and soil (abiotic factors) were the basic requirements for snail survival on beaches. Moreover, a lot of research on snail control has been focused on the specific influencing environmental factors for snail survival, such as the vegetation community structure, species composition, diversity index, and the physical and chemical properties of the soil. Most of the existing research has studied the influence of a single factor on snail population density. Conversely, there have been only a few studies focused on the food sources and food composition of the snails. The current research situation on snail control has indicated that the mechanisms underlying ecological snail control have not been systematically characterized. The question of whether biotic or abiotic factors were more important in influencing snail survival remains unclear. Afforestation on beaches has significantly suppressed snail density in China so far. In this study, we proposed that the reduction of snail density was not affected by a single factor but by the interactions of multiple related factors introduced by afforestation. Moreover, different biotic and abiotic factors have significantly different effects on snail control. Therefore the goal of this study was to evaluate the relative importance and interactions of related biotic and abiotic factors on snail density. Methods: Four major vegetation communities: Sedge, Reed, Artificial poplar (3 years of age) and Artificial poplar (5 years of age), on the beaches of the Yangtze River in China were selected for vegetation and snail surveys, as well as for soil sampling. Structural Equation Model (SEM) analysis was used to assess the interactions of biotic and abiotic factors in the context of snail ecology. The soil properties were considered as abiotic factors, while algae of Chlorophyta, Cyanophyta and Bacillariophyta phyla were considered to be biotic factors. In the path analysis, the total effect between the variables was the sum of the direct and indirect effects.ResultsThe snail density had significant correlations with soil properties, such as water content, bulk density, capillary porosity and pH value, as well as with all three types of soil algae, Chlorophyta, Cyanophyta, and Bacillariophyta. Snail density had a direct negative relationship with capillary porosity and soil bulk density, an indirect negative relationship with soil pH value and an indirect positive relationship with soil water content via soil algae. Meanwhile, as an important food source for the snail, the Chlorophyta, Cyanophyta and Bacillariophyta algae had a significant positive correlation with snail density. High soil pH had a negative impact on Chlorophyta, Bacillariophyta, while soil water content had a positive impact on Chlorophyta, and soil bulk density had a negative impact on Cyanophyta. In addition, the soil pH value and soil bulk density both had negative correlations with soil water content.ConclusionAfforestation of the beach environment can significantly reduce the snail population density by altering ecological factors. Soil algae (biological factors) might be the key element that drives ecological snail control. As important habitat determinants, the impact of the properties of the soil (non-biological factors) on the snail population was largely mediated through soil algae.

One of the most severe extinction events in Earth history, the Triassic–Jurassic extinction, struck against a backdrop of radical increases in atmospheric CO2and supercontinent breakup. This juxtaposition of first-order geophysical and biotic changes produced excellent case studies in Earth-Life Transitions. Recent recognition of a worldwide “carbonate gap” following the extinction has focused attention on causes, often invoked as eustacy or ocean acidification, but the ecology of the extinction aftermath remains poorly understood. Results from paleoecological studies on three separate Triassic–Jurassic records are presented and incorporated into regional depositional models. Examination of the Penarth Group of Great Britain reveals a widespread, laterally homogenous, level-bottom microbial stromatolite regime across the innermost ramp. The Sunrise Formation in Nevada, USA, was deposited during a biosiliceous (“glass”) regime dominated by demosponges across the inner ramp that lasted at least two million years. Investigations of the Pucará group in the central Andes of Peru revealed a demosponge-dominated level-bottom glass ramp with many similarities to the Nevada deposits, but offering broader regional extent and variation in recorded depositional settings. This suite of studies demonstrates state-shifts in marine ecological systems that also profoundly altered regional sedimentation regimes. The sponge-dominated systems produced glass ramp conditions instead of carbonate ramps, and indicate the importance of marine silica concentrations. The post-extinction changes in regional marine ecology demonstrate connectivity to changes in global climate and terrigenous weathering driven by global-scale geophysical processes.

Invasive alien species threaten global biodiversity and ecosystems. Understanding the context-dependency of invasion dynamics is crucial for uncovering the processes driving the establishment and spread of alien species. This study investigates how abiotic (soil characteristics) and biotic factors (resident vegetation diversity and similarity to the invader) affect the invasion success of Senecio inaequidens (South African ragwort) across high- and low-productivity habitats in northern Italy. Our results revealed that abiotic and biotic factors affect S. inaequidens success. We found evidence of biotic resistance from resident plant communities, driven mainly by diversity and cover. However, a negative relationship between S. inaequidens performance and both phylogenetic and functional similarity to resident species was found, indicating better performance when growing with more similar species. We additionally observed stronger resistance in more nutrient-rich environments, highlighting the context-dependent nature of such relationships. Our results suggest that S. inaequidens is more susceptible to competition than adverse abiotic conditions, making it as a good colonizer rather than a strong competitor. These findings emphasize the complexity of invasion dynamics and the importance of considering both biotic and abiotic factors in developing management strategies for invaded ecosystems.

Factors, at different scales, affecting the distribution of species of the genus Chthamalus Ranzani (Cirripedia, Balanomorpha, Chthamaloidea)

Understanding how abiotic, biotic, and historical factors shape species distributions remains a central question in ecology, but studies linking biotic factors to continental-scale patterns remain scarce. Here, we present a novel framework for simultaneously testing patterns expected when abiotic, biotic, or historical factors drive species range limits. We use ecological niche models to produce empirical estimates of the "biotic, abiotic, and movement" paradigm (BAM diagrams), which previously has been used only theoretically. On the basis of climatic and pollen data as well as explicit consideration of dispersal limitations, we implement the framework for a group of North American birds (Oreothlypis warblers) with clear habitat associations. Because the pollen-based predictor variables characterize vegetation, they represent biotic factors needed by each bird species. Although continental-scale patterns of distribution are traditionally attributed to abiotic factors, only one species matched the hypothesis of solely abiotic drivers. In contrast, pollen-based models indicate biotic drivers for two species, correctly predicting their absence in climatically suitable areas. These results highlight the feasibility of considering and quantifying the potential effects of biotic interactions on species ranges, especially when interactions can be decoupled from abiotic factors. Furthermore, the availability of pollen data now and in the Holocene highlights the potential of these data to be used to predict range shifts of other organisms tightly dependent on particular vegetation types.

Finkl, C.W. and Makowski, C., 2020. Coastal Belt Linked Classification (CBLC): A system for characterizing the interface between land and sea based on large marine ecosystems, coastal ecological sequences, and terrestrial ecoregions. Journal of Coastal Research, 36(4), 677–693. Coconut Creek (Florida), ISSN 0749-0208.The Coastal Belt Linked Classification (CBLC) is a novel approach based on interpretation of satellite images and assimilation of collateral data to characterize coastal belt segments that function as discrete interfaces between land and sea. This method is based on the formulation of concepts derived from the Biophysical Cross-shore Classification System (BCCS), the worldwide and regional-scale Large Marine Ecosystems (LME) classification, and the global distribution of terrestrial Ecoregions (ER). The coastal belt, a zone that extends across the shore from marine environments to inland terrestrial habitats, has recently been described in terms of cross-shore catenary sequences based on biophysical attributes of geomorphology and ecology. The CBLC formulates a cross-shore coastal classification by conjoining the Dominant Catenary Sequences (DCS) and Coastal Ecological Sequences (CES) with marine (LME) and terrestrial (ER) ecological systems; thus, a linkage is now provided between marine and terrestrial areas across coastal belts that function as transitional succession zones. This study proposes to combine the traditionally separated tripartite marine, coastal, and terrestrial delineations by melding them into a single descriptive code sequence that can be ascertained from interpretation of Google Earth satellite imagery and accessing collateral data via interactive LME and ER online platforms. Development of the CBLC is facilitated by the fact that LME and ER units are codified by numerals that are easily added to the formulated CES as prefixes and suffixes. The resulting combined alphanumeric code brings together a trove of information at different levels of investigation (Levels I – IV) that was heretofore not easily assimilated. This linkage of DCS and CES catenas with marine LME and terrestrial ER units brings added advantage to the interpretation of satellite imagery of the world's coasts, as it allows coastal belts to be viewed within the context of transitional interfaces between connected marine and terrestrial parameters. Recognition of coastal belts as interfacial bridges linking terrestrial and marine ecosystems into one codified descriptor sequence allows for cross-shore transects to be defined in the form of the Coastal Belt Linked Classification (CBLC) and provides an opportunity to fully comprehend the dynamic nature of coastal zones around the world.

The relative influence of abiotic and biotic factors on suitable habitat of Old World fruit bats under current and future climate scenarios

Both abiotic and biotic factors can influence distributions of invasive plant species, and it is important to understand how such factors contribute to invasion success in order to develop successful management strategies. Microstegium vimineum, known as stiltgrass, is an invasive annual grass in U.S. eastern deciduous forests that can outcompete native understory species, decrease diversity, and prevent the regeneration of native trees. Microstegium is also known to form associations with arbuscular mycorrhizal fungi (AMF), but research has yet to demonstrate whether this association has a role in Microstegium invasion and dominance over native vegetation. We conducted a field survey in invaded and uninvaded habitats across six sites near Louisville, KY, USA, to explore the relative importance of biotic versus abiotic factors in predicting Microstegium abundance and size. Canopy openness was the strongest predictor of Microstegium abundance, followed by soil moisture. Soil nitrogen was the strongest predictor of Microstegium tiller height. Surprisingly, AMF extraradical hyphal abundance and root colonization were not significant predictors of Microstegium abundance or size. In terms of abiotic factors, our results confirm previous studies that have demonstrated that Microstegium grows best in areas with high light and high soil moisture; however, our analysis provides further insight by assessing the relative importance of each of these factors for Microstegium invasion.

Drivers of tree survival in an evergreen-deciduous broadleaf karst forest in southwest China

Understanding the host–pathogen–environmental interactions in a pathosystem is essential for management of diseases and diminished crop yields. Abiotic stressors such as cold damage, water deficit, and high pH soils can be major limiting factors to tree fruit production. Along with decreased yields, these abiotic factors can have direct implications for disease severity within orchards. Cytospora plurivora is a ubiquitous fungal canker pathogen in western Colorado, USA and is a major focus in integrated pest management strategies. This research evaluated the influence of biotic and abiotic stress factors on peach tree health. Thirteen peach cultivars were placed under abiotic stress and inoculated with C. plurivora in greenhouse and field conditions. Under deficit irrigation, C. plurivora infections were significantly larger and more severe in both the greenhouse and field trials when compared with those under the full-irrigation controls. In controlled greenhouse conditions, a positive correlation between lesion size and water potential was evident, but no trend of cultivar tolerance was observed. Furthermore, increase in irrigation water pH, through additions of sodium carbonate and bicarbonate, in the greenhouse trials resulted in decreased leaf water potentials and increased pathogen necrotic tissue volumes (mm3). In field trials, there was no positive relationship between lesion size and water potential; trees with the most negative water potentials had the smallest lesions sizes that did not correspond to cultivar, suggesting that other abiotic or biotic factors may be shielding water stressed trees from increased pathogen aggression. This research highlights the importance of proper irrigation and soil pH management as tools for the management of Cytospora canker in peach orchards.

Premise of research. The dioecious palm Mauritia flexuosa plays a critical role in the ecology and economy of the Amazon. However, little is known about the relationship between habitat variation and the reproductive dynamics of this species. We quantified variation in fruit and seed production among three habitats in northern Brazilian Amazonia and identified the abiotic and biotic factors explaining these sources of variation.Methodology. Fruits and seeds from females in six sites (three habitats) were collected. Total fruit yield per individual, dry fruit mass, dry seed mass, and seed number per fruit were calculated for each female and habitat. Multiple linear regressions were conducted on abiotic (soil physical and chemical parameters, soil moisture, flooding levels, and photosynthetically active radiation) and biotic (height, diameter at breast height, number of leaves, and crown volume) factors to determine the relationship between these parameters and reproductive output.Pivotal results. Fruit mass, seed mass, and seed number were significantly lower in the disturbed savanna than in the undisturbed savanna ecotone and forest, although total fruit yield was highest in the disturbed savanna. Soil moisture and flooding during the wet season were the best predictors of fruit and seed output. Soil organic matter also explained variation in seed mass. The number of leaves, diameter at breast height, and height were all accurate predictors of reproductive output, but crown volume should not be used to estimate fruit yields.Conclusions. Habitat affects the reproductive dynamics of this species, which can be explained by abiotic factors such as moisture availability and biotic factors such as vegetative attributes. While two years of data are not sufficient to infer broad patterns, this study provides preliminary results about the factors that explain variation in fruit and seed formation of M. flexuosa. A long-term study relating seasonality, environmental factors, and the reproductive dynamics of M. flexuosa is warranted, with profound implications for plant reproduction and regeneration patterns.