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Ongoing habitat loss and fragmentation caused by human activities represent one of the greatest causes of biodiversity loss. However, the effects of habitat loss and fragmentation are not felt equally among species. Here, we examined how habitat loss influenced the diversity and abundance of species from different trophic levels, with different traits, by taking advantage of an inadvertent experiment that created habitat islands from a once continuous forest via the creation of the Thousand Island Lake, a large reservoir in China. On 28 of these islands with more than a 9000‐fold difference in their area (0.12–1154 ha), we sampled plants, herbivorous insects, and predatory insects using effort‐controlled sampling and analyses. This allowed us to discern whether any observed differences in species diversity were due to passive sampling alone or to demographic effects that disproportionately influenced some species relative to others. We found that while most metrics of sampling effort‐controlled diversity increased with island area, the strength of the effect was exacerbated for species in higher trophic levels. When we more explicitly examined differences in species composition among islands, we found that the pairwise difference in species composition among islands was dominated by species turnover but that nestedness increased with differences in island area, indicating that some species are more likely to be absent from smaller islands. Furthermore, by examining trends of several dispersal‐related traits of species, we found that species with lower dispersal propensity tended to be those that were lost from smaller islands, which was observed for herbivorous and predatory insects. Our results emphasize the importance of incorporating within‐patch demographic effects, as well as the taxa and traits of species when understanding the influence of habitat loss on biodiversity. [ABSTRACT FROM AUTHOR]

Carbon‐focused climate mitigation strategies are becoming increasingly important in forests. However, with ongoing biodiversity declines we require better knowledge of how much such strategies account for biodiversity. We particularly lack information across multiple trophic levels and on established forests, where the interplay between carbon stocks, stand age, and tree diversity might influence carbon–biodiversity relationships. Using a large dataset (>4600 heterotrophic species of 23 taxonomic groups) from secondary, subtropical forests, we tested how multitrophic diversity and diversity within trophic groups relate to aboveground, belowground, and total carbon stocks at different levels of tree species richness and stand age. Our study revealed that aboveground carbon, the key component of climate‐based management, was largely unrelated to multitrophic diversity. By contrast, total carbon stocks—that is, including belowground carbon—emerged as a significant predictor of multitrophic diversity. Relationships were nonlinear and strongest for lower trophic levels, but nonsignificant for higher trophic level diversity. Tree species richness and stand age moderated these relationships, suggesting long‐term regeneration of forests may be particularly effective in reconciling carbon and biodiversity targets. Our findings highlight that biodiversity benefits of climate‐oriented management need to be evaluated carefully, and only maximizing aboveground carbon may fail to account for biodiversity conservation requirements. [ABSTRACT FROM AUTHOR]

Biodiversity is threatened by global changes, but related research has focused primarily on species or functional group diversity, neglecting their interaction networks. The latter are particularly sensitive to global changes and essential for biodiversity maintenance. Furthermore, multiple global change factors are typically examined separately, rather than in concert which is more realistic in nature.To explore the responses of arthropod networks to multiple global changes, we conducted a field experiment in temperate grassland in northeast China, in which nitrogen (N) deposition, drought, snowmelt timing and their interactions were manipulated. We constructed and assessed networks of arthropod functional groups, and explored their responses to changes in plant communities and the abiotic environments.Nitrogen addition decreased arthropod network complexity because increased foliar N and simplified plant community strengthened trophic chains along a single pathway, weakening the net effect of other pathways. However, experimental drought decreased network complexity by filtering out plant species and changing micro‐habitats. While delayed snowmelt significantly increased arthropod abundance only in early spring, its interaction with N addition or with drought had various impacts on arthropod functional groups. Our results suggest that the interaction of arthropod consumers with plant species richness and with plant nutrients finally reduced the robustness, connectedness and function of entire species/functional group networks in response to global change factors.In conclusion, species loss and increasing plant nutrient concentrations are key factors simplifying networks under multiple global changes, and such simplification is likely to be strengthened if coupled with changes in micro‐habitats. Our study highlighted that the effects of multiple global change factors should be studied in concert, even though they occur in different seasons, so that their effects on ecological networks can be perceived as a panorama. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Abstract: Fishing activity has been suggested to affect food web structure and functioning of aquatic ecosystems. Based on changes of the mean trophic level index of fishery catch, the present study demonstrates long-term ecosystem impacts of fisheries in Lake Chaohu, a freshwater lake in Anhui Province, China. The decline of mean trophic level (MTL) in the last five decades, coupled with a dramatic increasing of the fishery catches from the lake, can be interpreted as a result of a decrease in the abundance of high trophic level, large piscivorous benthic fishes relative to low-trophic level, small planktivorous pelagic fishes. The mean trophic level of the total fishery catches declined as fishing effort (number of fishing boats and fishermen) increased, which suggests that an expansion of fishing capacity can lead to changes in the food web structures of a lake. Various direct and indirect relationships between MTL, nutrient concentrations and air temperatures were observed, suggesting that environmental changes, jointly with fishing, may have caused cascading effects which make the system less resistant to disturbance. In such context, our results, which complement traditional fisheries assessment, add to the understanding of the interactions among different trophic level of the ecosystem and their alterations due to fisheries and environmental changes. [Copyright &y& Elsevier]

Lake Taihu is a large, shallow, and eutrophic lake in China. It has provided local communities with valuable fisheries for centuries, but little is known of the trophodynamics, or of its faunal communities. Carbon and nitrogen isotopic composition was used to assess its trophic pathways and the food web structure [food sources and trophic levels (TL)]. Basal food sources were distinguishable based on their δC values, ranging from −27.2 to −15.2‰. Consumers were also well separated in δC (−26.9 to −17.9‰ for invertebrates and −25.7 to −18.1‰ for fishes), which allowed for an effective discrimination of carbon sources between these fauna. An average trophic enrichment factor of 3.4‰ was used to calculate the TLs based on δN of zooplankton, with results indicating a food web having four TLs. Although δN values overlap and cover a large range within trophic compartments, the isotopic signatures of the species assessed revealed a general trend of N enrichment with increasing TL. Stable isotope signatures were also used to establish a general food web scheme in which five main trophic pathways were analyzed. [ABSTRACT FROM AUTHOR]

Abstract: Polybrominated diphenyl ethers (PBDEs) are of great environmental concern due to bioaccumulation in different food chains. Trophodynamics of PBDEs in freshwater food chain is an important criterion for assessing their ecological risk. In the study, PBDEs were analyzed in sixteen aquatic species collected from Baiyangdian Lake, North China. The concentrations of nine PBDE congeners (BDE-28, -47, -66, -99, -100, -85, -153, -154, and -183) in aquatic organisms ranged from 3.4 to 160.2ng/g lipid weight. BDE-47 was the predominant PBDE congener in most samples except for river snails and swan mussels. BDE-209 was detected in 50% of biota samples, which indicated the bioavailability of BDE209. Correlation between lipid-normalized concentrations of PBDEs and trophic levels determined by stable isotope nitrogen technologies confirmed that PBDEs were biomagnified in the freshwater food chain. The trophic magnification factors (TMFs) ranged from 1.3 to 2.1 for PBDE congeners, greater than one, indicating the biomagnification potential for the PBDE congeners in the freshwater food chain. The relationship between TMFs and Log K ow (octanol–water partition coefficient) indicated that the phenomenon of trophic magnification for lowly brominated congeners was obvious in the freshwater food chain. [Copyright &y& Elsevier]

Conventional agriculture has induced serious environmental problems that are severe under greenhouse conditions because of the large chemical inputs and high levels of disturbance. Organic and low input management practices with the application of organic amendments, and elimination or reduction of synthetic fertilizer inputs and pesticides, were proposed to alleviate these problems. Existing studies have assessed the effect of different management practices on the communities of one or several types of soil organisms, but the effects on the whole soil food web are unknown. Therefore, we analyzed the impact of three management practices—organic (ORG), low input (LOW) and conventional (CON)—on the structure and biomass of soil food webs under greenhouse conditions in northern China. A range of soil biota including microorganisms, protozoa, nematodes, microarthropods, and annelids, were collected to construct the soil food web. Sampling events were carried out monthly from August to December for 0–10 and 10–20 cm soil depths. The results showed that the number of functional groups, connectance, maximum and mean of food chain length, and food web diversity were highest in ORG, indicating that the soil food web was more complex under organic management practices than the other practices tested. The total food web biomass presented a decreasing sequence of ORG > LOW > CON in both soil layers. For each trophic level, the biomass was greater in ORG than in LOW and CON, and this advantage for ORG increased with increasing trophic level, indicating that organic management practices were more beneficial to biota at higher trophic levels. The principal component analysis based on functional groups showed that the soil food web composition of LOW was between that of ORG and CON, and that of LOW and CON were more similar at 0–10 cm depth. The Bray-Curtis similarity index showed lower variability in ORG than in LOW and CON, indicating a relatively stable soil food web in the organic greenhouse. In summary, organic management practices under greenhouse conditions enhanced soil food web biomass and complexity, which was likely driven by supply of manure and the elimination of chemical inputs. • Soil food web structure and biomass was estimated under greenhouse conditions. • Organic management practices enhanced soil food web complexity. • Organic management practices increased soil food web biomass. • Increased biomass in the organic system was more obvious at higher trophic levels. [ABSTRACT FROM AUTHOR]

The distribution and bioconcentration of polycyclic aromatic hydrocarbons (PAHs) in water, suspended particulate material (SPM), algae, and zooplankton samples from the Pearl River Delta (PRD), South China, were investigated. The PAHs in the water and SPM samples is significantly associated with chlorophyll a (Chl a), implying the important role of the aquatic productivity on PAH distribution. PAHs in the water or SPM samples were strongly correlated to dissolved organic carbon (DOC) or algal particulate organic carbon (A-POC). Moreover, the log bioconcentration factor (BCF) values (mL g−1) of PAHs in both the algae and zooplankton samples were linearly related to their log octanol-water coefficient (Kow) values. However, the slopes of these relationships were negatively correlated with Chl a, attributing to the difference in the dominant plankton species or the non-equilibrium exchange between air-water-biota. The above results indicate the important role of trophic levels on the distribution and bioaccumulation of PAHs. Unlabelled Image • The phytoplankton OC contributed 36.7% of POC. • PAHs respectively showed significant correlations with DOC, POC, and Chl a. • Aqueous and particulate PAHs were strongly correlated to DOC or algal POC. • Log BCF values of PAHs in planktons were linearly related to their log K ow values. • Algal biomass played an important role on the partitioning and uptake of PAHs. [ABSTRACT FROM AUTHOR]

Coastal lagoons are often characterized by eutrophic conditions which are known to impair the structure and functioning of both pelagic and benthic compartments. However, the manner in which eutrophication triggers a series of cascade effects in the whole food web in coastal lagoons has received little attention. Using stable isotope (SI) analyses, we investigated the food web structure in the hypertrophic lagoon of Yundang (Xiamen, China) in two periods of the year characterized by the recurrent alternation of Ulva lactuca and phytoplankton blooms in the cool (March) and warm (September) seasons, respectively. Large temporal fluctuations in the dominance of primary producers (i.e. macroalgae vs. phytoplankton) and, thus, in the available food items, were reflected in major changes in the diet and SI signals of several primary consumers, such as the amphipod Grandidierella japonica, the polychaetes Neanthes japonica and Capitella capitata, and omnivorous fishes (i.e. Mugil cephalus, Oreochromis niloticus, and Sardinella zunasi), while these changes were limited in top carnivorous fishes, such as Lateolabrax japonicus. Furthermore, reduced macrozoobenthic abundance available for omnivores in September was found to force omnivores to switch their feeding habits to those of herbivores. The present study provides evidence that the periodical alternation of macroalgal and phytoplankton blooms throughout the year strongly affect the relations among different trophic levels leading to a cascading effect across the whole food web and to major changes in the lagoon's food web structure. Importantly, our study shows that the lagoon's food web structure under persistent eutrophic conditions can still cope with seasonal changes in primary energy source type from macroalgae to microalgae due to the ability of omnivorous fishes to conduit different food sources up to the highest trophic levels. Thus, this study suggests that in such a highly variable eutrophic system, omnivores play a central role in the lagoon's functioning, and help to sustain the biological resources and the ecosystem services provided by the lagoon., (Copyright © 2020 Elsevier Ltd. All rights reserved.)