Surface Dwelling Research Articles

Hypoxia-sonic hedgehog axis as a driver of primitive hematopoiesis development and evolution in cavefish

The teleost Astyanax mexicanus consists of surface dwelling (surface fish) and cave dwelling (cavefish) forms. Cavefish have evolved in subterranean habitats characterized by reduced oxygen levels (hypoxia) and exhibit a subset of phenotypic traits controlled by increased Sonic hedgehog (Shh) signaling along the embryonic midline. The enhancement of primitive hematopoietic domains, which are formed bilaterally in the anterior and posterior lateral plate mesoderm, are responsible for the development of more larval erythrocytes in cavefish relative to surface fish. In this study, we determine the role of hypoxia and Shh signaling in the development and evolution of primitive hematopoiesis in cavefish. We show that hypoxia treatment during embryogenesis increases primitive hematopoiesis and erythrocyte development in surface fish. We also demonstrate that upregulation of Shh midline signaling by the Smoothened agonist SAG increases primitive hematopoiesis and erythrocyte development in surface fish, whereas Shh downregulation via treatment with the Smoothened inhibitor cyclopamine decreases these traits in cavefish. Together these results suggest that hematopoietic enhancement is regulated by hypoxia and Shh signaling. Lastly, we demonstrate that hypoxia enhances expression of Shh signaling along the midline of surface fish embryos. We conclude that hypoxia-mediated Shh plasticity may be a driving force for the adaptive evolution of primitive hematopoiesis and erythrocyte development in cavefish.

Morphometry of Demodex species in dogs

The present study was carried out to record the mean length and width of gnathosoma, podosoma and opisthosoma of two different Demodex mites in dogs. The mean lengths gnathosoma, mean width of gnathosoma, podosoma and opisthosoma did not differ significantly (P>0.05); mean length of podosoma, opisthosoma and the total body differed significantly (P<0.05) between both types of mites of Demodex canis and Demodex cornei. The present study suggests that apart from examination of deep skin scrapings, tape impression smears may also be made a regular practice while dealing with demodicosis suspected dogs in order to detect the surface dweller like Demodex cornei

Protection mechanism of B4C–TiB2–SiC composite ceramic under ultra-high velocity impact

As the penetration technology develops and the projectile velocity increases, it becomes imperative to investigate the protection mechanism of high-performance ceramic under hypervelocity impact. The impact process of tungsten alloy projectile penetrated into B4C–TiB2–SiC composite ceramic target using ballistic test and finite element simulation at an ultra-high velocity of 2154 m/s was researched in the present study. Additionally, the protection mechanisms were described in terms of the morphology of target damage, the behavior of projectile kinetic energy dissipation, and the temperature field cloud. The findings from the ballistic experiments highlighted that the formation of macro-damage areas (concentrated damage, cone crack, circumferential crack, and radial crack areas) and micro-fragmentation zones could consume a significant amount of impact energy. The mixed fracture mode and the typical inelastic deformation characteristics (dislocations and micro-twinning) contributed to the energy dissipation. Simulation results indicated that the surface dwell effect of the projectile exhibited the highest rate of energy consumption. Furthermore, the temperature field results indicated that the maximum temperature on composite ceramic surface could reach 2310 K, which was below the melting point of B4C ceramic (2723 K). However, this temperature could cause the melting of the majority of metal materials. Therefore, ceramic materials exhibited a significant advantage under conditions of ultra-high impact velocities.

Large shift in the upper water column characteristics of the west-central Bay of Bengal during the last glacial-interglacial transition

The upper water column structure in the Bay of Bengal is strongly influenced by the monsoon and associated processes. However, the records of variation in water column stratification during different monsoon phases, are scarce from this region. Here, we have reconstructed the variation in monsoon induced upwelling, mixed layer and thermocline during the last glacial-interglacial transition, by using the relative abundance of mixed layer and thermocline dwelling planktic foraminifera, relative abundance of Globigerina bulloides and the stable oxygen isotopic ratio (δ18O) of surface dwelling Globigerinoides ruber. We report a weaker upwelling during the last glacial interval and late Greenlandian-Northgrippian Age, and strong upwelling during the deglaciation and Meghalayan Age. The intense upwelling shoaled the thermocline during the early glacial interval, last glacial maximum, late deglaciation and the Meghalayan Age. The mixed layer depth increased during the early deglaciation and Late Greenlandian-Northgrippian due to the reduced upwelling and stronger winter monsoon. The shift in the position of the core site with respect to the low salinity coastal currents, due to the rising sea level, also influenced the upper water column structure in the west-central Bay of Bengal. Therefore, the reorganization of the upper water column structure in the west-central Bay of Bengal, on the glacial-interglacial time scale, was mainly influenced by a combination of the upwelling, fresh water influx, sea level and winter monsoon.

Limited range shifting in biocrusts despite climate warming: A 25‐year resurvey

Abstract The ranges of many species globally have already shifted to maintain climatic equilibrium in the face of climate change. Biocrusts—soil surface dwelling communities of lichens, bryophytes and microbes—play important functional roles in many ecosystems, particularly in drylands. Compared to better studied animal and plant taxa, dryland biocrusts have different establishment requirements and have never been assessed for historical range shifts. Here, we revisited the sites (N = 204) of a 25‐year‐old biocrust survey across a large area (400,000 km2) of drylands in south‐eastern Australia. We used quadratic models to quantify changes in the climate niches of 15 lichen, eight moss and five liverwort taxa, as well as biocrust cover and richness. Our models showed that the observed climatic niches of most taxa have become hotter and drier in the past quarter century, yet the responses of the vast majority of taxa are consistent with remaining in the same geographic space. A similar pattern was observed at the community level, where the peak of biocrust cover and richness now occurs in a hotter, drier environment. Notable exceptions were the liverwort Riccia lamellosa and lichens in the genera Cladonia and Xanthoparmelia, which showed signs of contraction at their arid range edges. Unlike more mobile taxa, most biocrust species have yet to shift geographically and may already be lagging behind the pace of climate change. One explanation for the mortality lag is that long‐term climate variability in the system is extensive, which may have selected for the ability to withstand multi‐year warm periods as long as there is an eventual return to milder conditions. However, no forecasts of future climate include a return to milder conditions, suggesting there will be an eventual loss of ecosystem multifunctionality at the contracting front. Expansion lags are most likely due to delays in the mortality of competing vascular plants. Synthesis: Our study provides a valuable contribution to the knowledge of range shifts in understudied taxa and highlights a future need to promote the expansion of biocrusts to maintain the provision of ecosystem functions and services across their range.

Risk assessment of microplastics in fish assemblage based on ecological preferences in an interconnected and polluted river system

Risk assessment of microplastics (MPs) contamination in the assemblage of 15 important fish species with different feeding habits and microhabitats was studied in the River Ravi, Pakistan. Fishes with different feeding habits (omnivore, herbivore, and carnivore) and microhabitat preferences (surface, column, and bottom dweller) were sampled at Balloki and Sidhnai barrages during the post-monsoon seasons of 2019–2020. The gastrointestinal tract (GIT) of fish samples were found to be contaminated with MPs, with an average of 28.1 ± 20.7 MPs/individual and 26.8 ± 15.9 MPs/individual at Balloki and Sidhnai barrages, respectively. The surface dweller fish exhibited the highest MPs abundance, followed by the bottom dweller and column dweller. In addition, the highest MPs recovered from the omnivore generalist feeding group as compared to herbivores and carnivores. The fibers were the most abundant shape and generally made up of polyethylene terephthalate (PET) and polyethylene (PE). These PET and PE (low-density MPs) exhibit low hazard level, whereas high-density MPs with high hazard level and rarely present in GIT of sampled fishes. Based on MP polymer toxicity assessment, nine fish species were categorized in minor risk, two species in medium risk, and four species in highrisk group. Bottom dwelling fishes were at the highest plastic polymer risk level III due to the presence of a high density of MPs with high toxicity hazards. The high-risk prone fishes are under direct threat from MPs pollution, which may disrupt the ecological integrity of the river ecosystem and human health. The findings of the current study highlight the urgent need to address plastic pollution issues in River Ravi, and will be helpful for managers, researchers, and fisheries experts to mitigate this emerging challenge.speciesspecies

The overview of lithobiomorph centipedes (Chilopoda, Lithobiomorpha) from caves of Slovenia

Centipedes of temperate regions can be found in various habitats, including forest litter, soil or caves. Slovenia, situated in the Northwestern Balkans, has rich centipede fauna, with one of the earliest scientific descriptions of a cave centipede, Lithobius stygius Latzel, 1880, from Postojnska jama. Many lithobiomorph species have been reported from Slovenian caves, but the data on their occurrence are scattered in the literature or public collections, and several specimens have even remained unexamined. Here we present the overview of lithobiomorph centipedes found in Slovenian caves. Altogether, 21 lithobiomorph species were found in 160 localities. The majority of the records, 319 out of 410, are published for the first time. Only three species are considered exclusively subterranean species, L. stygius, L. zveri and Eupolybothrus obrovensis, while other species are surface dwellers. The potential explanation of surface species presence in caves is discussed. We comment on cases of unresolved taxonomical status and present suggestions for further research needed to resolve them. Even though lithobiomorph centipedes often occur in caves, their role and importance in subterranean habitats remain to be studied.

Space Diplomacy and the ‘Overview Effect’

Summary Astronauts looking at Earth from orbital or lunar missions often say they cannot see borders and boundaries that mean so much to surface dwellers, an essential feature of the ‘Overview Effect’, a term the author coined to describe the identity shift that takes place for many space travellers. What does this portend for the future? Should we simply forget borders, since they are merely products of our minds? What about diplomacy, which is all about borders and boundaries insofar as it is about inter-national relations. Will the art of diplomacy change as nation-states send more residents to explore the rest of the solar ecosystem? This question seems more relevant than ever, while war rages, largely over borders and boundaries, in the heart of Europe. We consider how the ‘Overview Effect’ influences communication, persuasion, and bargaining among state and non-state actors active in determining the shape of our future spacefaring civilisation.

The Loop Current Circulation Over the MIS 9 to MIS 5 Based on Planktonic Foraminifera Assemblages From the Gulf of Mexico

AbstractThe loop current (LC) in the Gulf of Mexico (GoM) is part of the western North Atlantic circulation. Recording its strength and slowdown variations can help us characterize the regional climate over the Late Pleistocene. To reconstruct the sea surface and the LC intensity in the eastern GoM, we study the distribution patterns of planktonic foraminifera in the core EN‐032‐18PC, spanning the end of Marine Isotope Stage (MIS) 9 to early MIS‐4. We reconstructed a sequence of paleoceanographic events based on stable isotopes (δ18O and δ13C) of the surface dweller Globigerinoides ruber and two faunal assemblages. The first assemblage explains most of the glacial and late interglacial periods, suggesting a subtropical environment with a deep thermocline and a reduced LC due to a moderate inflow of warm Caribbean waters. The second assemblage explains the warmest interglacial substages, dominated by tropical species, a shallow thermocline, and an extended LC, driven by summer insolation. Overall, surface ocean conditions led to more ecological successions and instability during the warmest interglacial substages than during glacial periods, as supported by the stable isotope records. Besides the GoM relationship to AMOC, as a regulator of heat transport to higher latitudes, we suggest that fluctuations in the LC rely on the migration of atmospheric circulation patterns and astronomical insolation forcing.

Metagenomic analysis reveals hidden links between gut microbes and habitat adaptation among cave and surface dwelling Sinocyclocheilus species.

Intestinal microbes are closely related to vital host functions such as digestion and nutrient absorption, which play important roles in enhancing host adaptability. As a natural "laboratory", caves provide an outstanding model for understanding the significance of gut microbes and feeding habits in the habitat adaptability of hosts. However, research on the relationship between gut microbes, feeding habits, and the adaptability of troglobites remains insufficient. In this study, we compared the characteristics of the intestinal microbes of Sinocyclocheilus cavefish and surface fish and further established the relationship between intestinal and habitat microbes. Furthermore, we conducted environmental DNA (eDNA) (metabarcoding) analysis of environmental samples to clarify the composition of potential food resources in the habitats of the Sinocyclocheilus cavefish and surface fish. Results showed that the structure of the Sinocyclocheilus gut microbes was more related to ecological type (habitat type) than phylogenetic relationships. While horizontal transfer of habitat microbes was a source of gut microbes, hosts also showed strong selection for inherent microbes as dominant microorganisms. Differences in the composition and structure of gut microbes, especially dominant microbes, may enhance the adaptability of the two Sinocyclocheilus fish types from the perspectives of food intake, nutrient utilization, and harmful substance metabolism, suggesting that food resources, predation patterns, intestinal flora, digestive and absorptive capacity, and feeding habits and preferences are linked to habitat adaptability. These results should facilitate our understanding of the significance of fish gut microbes to habitat adaptation and provide a new perspective for studying the adaptive mechanisms of cavefish.

Coastal Sargassum Level Estimation from Smartphone Pictures

Since 2011, significant and atypical arrival of two species of surface dwelling algae, Sargassum natans and Sargassum Fluitans, have been detected in the Mexican Caribbean. This massive accumulation of algae has had a great environmental and economic impact. Most works addressing this topic use high-resolution satellite imagery which is expensive or may be time delayed. We propose to estimate the amount of Sargassum based on ground-level smartphone photographs that, unlike previous approaches, is much less expensive and can be implemented to make predictions almost in real time. Another contribution of this work is the creation of a Sargassum images dataset with more than one thousand examples collected from public forums such as Facebook or Instagram, labeled into 5 categories of Sargassum level (none, low, mild, plenty, and excessive), a relevant difference with respect to previous works, which only detect the presence or not of Sargassum in a image. Several state-of-the-art convolutional networks: AlexNet, GoogleNet, VGG, and ResNet, were tested using this dataset. The VGG network trained under fine-tuning showed the best performance. The results of the carried out experiments show that convolutional neuronal networks are adequate for providing an estimate of the Sargassum level only from smartphone cameras images.

Orbital control on the thermocline structure during the past 568 kyr in the Solomon Sea, southwest equatorial Pacific

The Solomon Sea is the main source of the equatorial undercurrent and the main crossroad of the equatorial region and the South Pacific Ocean. Based on multi-species planktonic foraminiferal geochemical proxies, here we reconstruct the vertical thermal-hydrological variabilities over the last 568,000 years in the Solomon Sea. The proxies used include the differences between δ18O data of the surface dweller Globigerinoides ruber (white) and the subsurface dweller Pulleniatina obliquiloculata (Δδ18Oc), the sea surface temperature (SST) and the upper thermocline temperature (UTT) as well as their differences (ΔT), and the seawater oxygen isotope differences (Δδ18Ow). Both the SST and UTT records feature similar timing of warming, which is 2–4 kyr earlier than the G/IG boundaries for the past six terminations. Different from the other five terminations, both SST and UTT records of Termination V show a persistent and early increase of 5–7 °C in 10 kyr since ∼440 ka. On the obliquity band, higher SST and UTT correspond to larger obliquity, suggesting higher subtropical South Pacific input. This argument is supported by lower ΔT and higher Δδ18Ow. In the meantime, higher SST and UTT also correspond to precession minimum, suggesting an expansion of the mixed layer with lower ΔT and greater Δδ18Ow. Our results show complex interactions between precipitation-evaporation and water masses exchange in the Solomon Sea. The clear obliquity signal observed in multiple proxies reveals strong interactions between the Solomon Sea and the mid-high latitude South Pacific regions.

Cretaceous-Tertiary boundary marine extinctions: The Russian platform record

Floral, faunal and stable isotope evidence in a continuous sequence of latest Cretaceous and earliest Tertiary shallow water marine deposits in the Mangyshlak Peninsula, USSR suggest sudden and severe cooling possibly accompanied by increased salinities of the surface water al the Maastrichtian/Danian (M/D) boundary, immediately followed by marked warming and decreased salinities. Geologic evidence indicates that the temperature decline was coeval with widespread and intense volcanic activity which reached a peak at the close of the Mesozoic Era. Volatile emissions led to acid rain which depressed the pH of surface water. lncreased acidity temporarily prohibited calcite nucleation of the surface dwelling warm-water plankton. Superimposed upon decreased alkalinity, severe and rapid climatic changes caused the extinction of calcareous phyto and zooplankton. These results provide the most complete nanno, micro and macrofossil data as well as geochemical and clay mineralogical record from a single region across the paleomagnetically dated Cretaceous/Tertiary (K/T) boundary to date.

Earthworm Abundance Increased by Mob-Grazing Zero-Tilled Arable Land in South-East England

Regenerative agriculture is a potential alternative to conventional agricultural systems. It integrates the components of zero-tillage, permanent soil cover, diverse crop rotations and rotational or mob-grazing by ruminant livestock. Earthworms are beneficial soil macrofauna and function as indicators of soil health. A need exists to identify how earthworm populations are affected when all four regenerative agriculture components are implemented simultaneously. This study investigates earthworm abundance in three split-plot treatments located on adjacent land within the same farm: (1) ungrazed permanent grassland, (2) a three-year grass-clover ley within an arable zero tillage system without grazing and (3) identical to treatment 2 but with mob-grazing. Earthworms were sampled using soil pits and classified into four functional groups: epigeic (surface dwellers), endogeic (sub-surface), anecic (deep soil) and juveniles. The total earthworm count, epigeic and juvenile functional groups were significantly (p ≤ 0.05) higher in treatment (3), the arable zero tillage system with mob-grazing. Mob-grazing increases the diversity of carbon sources available to earthworms and has a positive impact on earthworm abundance and functional group diversity within the arable rotation under evaluation.

Reevaluating scorpion ecomorphs using a na\xefve approach

BackgroundEcomorphs create the opportunity to investigate ecological adaptation because they encompass organisms that evolved characteristic morphologies under similar ecological demands. For over 50 years, scorpions have been empirically assigned to ecomorphs based on the characteristic morphologies that rock, sand, vegetation, underground, and surface dwellers assume. This study aims to independently test the existence of scorpion ecomorphs by quantifying the association between their morphology and ecology across 61 species, representing 14 families of the Scorpiones order.ResultsWithout a priori categorization of species into ecomorphs, we identified four groups based on microhabitat descriptors, which reflect how scorpion ecospace is clustered. Moreover, these microhabitat groups, i.e., ecotypes, have significantly divergent morphologies; therefore, they represent ecomorphs. These ecomorphs largely correspond with the ones previously described in the literature. Therefore, we retained the names Lithophilous, Psammophilous, and Pelophilous, and proposed the name Phytophilous for vegetation dwellers. Finally, we sought to map the morphology-ecology association in scorpions and found that the morphological regions most tightly associated with ecology are at the extremities. Moreover, the major trend in ecomorphological covariation is that longer walking legs and relatively slender pedipalps (pincers) are associated with sandy microhabitats, while the inverse morphological proportions are associated with rocky microhabitats.ConclusionsScorpion ecomorphs are validated in a naïve approach, from ecological descriptors and whole body anatomy. This places them on a more solid quantitative footing for future studies of ecological adaptation in scorpions. Our results verify most of the previously defined ecomorphotypes and could be used as a current practice to understand the adaptive significance of ecological morphology.

Differential accumulation of polycyclic aromatic hydrocarbons (PAHs) in three earthworm ecotypes: Implications for exposure assessment on historically contaminated soils

This study compared accumulation of the 16 US-EPA priority polycyclic aromatic hydrocarbons (PAHs) in three different earthworm ecotypes, Amynthas sp., Eisenia fetida, and Lumbricus terrestris, in four historically (> 50 years) contaminated manufactured gas plant (MGP) soils using bioassays. Epi-endogeic deep burrowing and soil ingesting Amynthas sp. accumulated significantly more ∑16 PAHs than any other species (upto 8.7 times more), and epigeic surface dwelling E. fetida showed the lowest ∑16 PAH accumulation. Results indicated the importance of earthworm habit and physiology on PAH partitioning into earthworm lipids. Exposure to soil borne PAHs via the gut, as compared with passive diffusion from pore water, was important in species tested, being most evident in burrowing species Amynthas sp. and L. terrestris and for the desorption-resistant higher molecular weight (HMW) PAHs. Biota-soil accumulation factors (BSAF) were low, as influenced by aging, sequestration and strong PAH sorption to secondary sorptive phases in the historically contaminated soils. Bioconcentration factors (BCFs) calculated from freely dissolved pore water PAH concentrations derived from polyoxymethylene solid-phase extractions (POM) were species specific, indicating stronger relationships with octanol-water partition coefficient (KOW) for Amynthas sp. and L. terrestris than for E. fetida. Modelling demonstrated that KOW values were not a reliable proxy for BCF in equilibrium partitioning theory (EqPT) to predict bioavailability for the range of earthworms tested, being less accurate for E. fetida compared to the burrowing species. The study showed that including burrowing and soil feeding earthworm species, such as Amynthas sp. and L. terrestris, in standard testing would benefit regulatory decisions for more accurate quantification of PAH bioavailability in ecological risk assessment on historically contaminated soils.

Novel experimental apparatus for laboratory measurements of phototaxis: A comparison between amphipod species

AbstractIntricate adaptations to visual systems have allowed amphipods to thrive in extreme habitats like caves. In addition to rearranging ocular dioptric elements, adaptations have also been made to photobehaviors to accommodate the environmental conditions of their habitats. Given the prevalence or absence of discernible eyes or photoreceptors across species, phototaxis is a commonly used behavior to assess light sensing mechanisms. Amphipod photobehaviors have increasingly been utilized within neuroethological and ecotoxicological studies but the quality of light used during laboratory experiments is often overlooked. We describe a novel experimental chamber that allows for accurate and efficient measurement of phototaxis under precisely controlled light conditions. We used this experimental chamber to test phototaxis in two related amphipod species, one subterranean (Stygobromus tenuis potomacusHolsinger, 1967) and one surface dwelling (Crangonyx shoemakeriHubricht & Mackin, 1940). Our results confirm that the behaviors of these species are indicative of natural photopreferences and that in certain populations, these preferences vary with light quality. This low cost and efficient method could easily be applied to a variety of animal models and light conditions, allowing for a reproducible and high throughput method to measure phototaxis in laboratory trials.

Measurement of the temperature dependence of dwell time and spin relaxation probability of Rb atoms on paraffin surfaces using a beam-scattering method

The scattering of Rb atoms on an anti-relaxation coating was studied. No significant change in the spin relaxation probability of Rb atoms by single scattering from a tetracontane surface was observed by cooling the film from 305 to 123 K. The mean surface dwell time was estimated using a time-resolved method.Delay-time spectra, from which mean surface dwell times can be estimated, were measured at 305, 153, and 123 K, with a time window of $9.3\times 10^{-5}$ s. The increase in mean surface dwell time with cooling from 305 to 123 K was smaller than $4.4\times 10^{-6}$ s, which is significantly smaller than the value expected from the mean dwell time at room temperature measured using the Larmor frequency shift. These results can be explained by assuming a small number of scattering components, with a mean surface dwell time at least three orders of magnitude longer than the majority component.

Tryptophan Hydroxylase 2 Deficiency Modifies the Effects of Fluoxetine and Pargyline on the Behavior, 5-HT- and BDNF-Systems in the Brain of Zebrafish (Danio rerio).

The mechanisms of resistance to antidepressant drugs is a key and still unresolved problem of psychopharmacology. Serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) play a key role in the therapeutic effect of many antidepressants. Tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in 5-HT synthesis in the brain. We used zebrafish (Danio rerio) as a promising model organism in order to elucidate the effect of TPH2 deficiency caused by p-chlorophenylalanine (pCPA) on the alterations in behavior and expression of 5-HT-related (Tph2, Slc6a4b, Mao, Htr1aa, Htr2aa) and BDNF-related (Creb, Bdnf, Ntrk2a, Ngfra) genes in the brain after prolonged treatment with two antidepressants, inhibitors of 5-HT reuptake (fluoxetine) and oxidation (pargyline). In one experiment, zebrafish were treated for 72 h with 0.2 mg/L fluoxetine, 2 mg/L pCPA, or the drugs combination. In another experiment, zebrafish were treated for 72 h with 0.5 mg/L pargyline, 2 mg/L pCPA, or the drugs combination. Behavior was studied in the novel tank diving test, mRNA levels were assayed by qPCR, 5-HT and its metabolite concentrations were measured by HPLC. The effects of interaction between pCPA and the drugs on zebrafish behavior were observed: pCPA attenuated “surface dwelling” induced by the drugs. Fluoxetine decreased mRNA levels of Tph2 and Htr2aa genes, while pargyline decreased mRNA levels of Slc6a4b and Htr1aa genes. Pargyline reduced Creb, Bdnf and Ntrk2a genes mRNA concentration only in the zebrafish treated with pCPA. The results show that the disruption of the TPH2 function can cause a refractory to antidepressant treatment.

Beyond the single index: Investigating ecological mechanisms underpinning ecosystem multifunctionality with network analysis.

Ecosystems simultaneously deliver multiple functions that relate to both the activities of resident species and environmental conditions. One of the biggest challenges in multifunctionality assessment is balancing analytical simplicity with ecosystem complexity. As an alternative to index‐based approaches, we introduce a multivariate network analysis that uses network theory to assess multifunctionality in terms of the relationships between species' functional traits, environmental characteristics, and functions. We tested our approach in a complex and heterogeneous ecosystem, marine intertidal sandflats. We considered eight ecosystem function, five macrofaunal functional trait groups derived from 36 species, and four environmental characteristics. The indicators of ecosystem functions included the standing stock of primary producers, oxygen production, benthic oxygen consumption, DIN (ammonium and NOx efflux) and phosphate release from the sediments, denitrification, and organic matter degradation at the sediment surface. Trait clusters included functional groups of species that shared combinations of biological traits that affect ecosystem function: small mobile top 2 cm dwellers, suspension feeders, deep‐dwelling worms, hard‐bodied surface dwellers, and tube‐forming worms. Environmental characteristics included sediment organic matter, %mud, %shell hash, and %sediment water content. Our results visualize and quantify how multiple ecosystem elements are connected and contribute to the provision of functions. Small mobile top 2 cm dwellers (among trait clusters) and %mud (among environmental characteristics) were the best predictor for multiple functions. Detailed knowledge of multifunctionality relationships can significantly increase our understanding of the real‐world complexity of natural ecosystems. Multivariate network analysis, as a standalone method or applied alongside already existing single index multifunctionality methods, provides means to advance our understanding of how environmental change and biodiversity loss can influence ecosystem performance across multiple dimensions of functionality. Embedding such a detailed yet holistic multifunctionality assessment in environmental decision‐making will support the assessment of multiple ecosystem services and social‐ecological values.