Increasing Habitat Complexity Research Articles

Habitat-mediated direct and indirect interactions in a marine sedimentary system from Atlantic Canada

Trophic cascades focusing on direct (consumptive) effects have been well studied in marine ecosystems. However, less attention has been given to cascades involving indirect interactions embedded in distinct habitats. We focused on the interactions between a non-indigenous predator (the green crab Carcinus maenas), a consumer (the mud crab Panopeus herbstii), and a prey species (juvenile eastern oysters Crassostrea virginica). These interactions were studied in 3 small yet distinct habitats of increasing complexity: bare sediments, patches of blue mussels Mytilus edulis (BM), and a unique habitat consisting of giant Irish moss Chondrus crispus and mussels combined (IMBM). In the field, green crab predation rates on mud crabs were estimated in each of the abovementioned habitats using tethering experiments. The results showed that green crab foraging was most effective in bare sediments and least effective in IMBM, i.e. the least and most complex habitats, respectively. Trials conducted in the laboratory with mud crabs foraging over oysters showed a similar outcome: oyster mortality rates declined with increased habitat complexity. However, when trials were conducted in the presence of a green crab, this pattern reversed, and oyster mortality was lowest in bare sediments. Mud crab behavior was consistent with these results: in the presence of a green crab, mud crabs were less active and spent more time sheltering, whereas in its absence, the opposite pattern was observed, especially in bare sediments. These behaviorally driven indirect interactions are dependent on the presence of a non-indigenous predator and mediated by the type of habitat.

Life on every stone: Characterizing benthic communities from scour protection layers of offshore wind farms in the southern North Sea

The scour protection layer (SPL) is a layer of large stones placed around man-made structures in the marine environment, preventing sediment scouring while also providing new hard substrate and potentially increasing the structural complexity of the original environment. This fosters development of diverse benthic communities, supporting high abundance of organisms. Future SPLs are therefore a potential tool for the ecological enhancement of degrading marine habitats following the principles of nature-inclusive design. Yet, factors that shape the benthic communities on SPLs are poorly understood. Here, we analysed existing data from SPLs from offshore wind farms and a gas platform in the southern North Sea to determine how SPL characteristics affect the biofouling community structure. We combined this analysis with an in-situ experiment testing for the effects of habitat complexity on SPL communities. Our results demonstrate that abundant and diverse communities are present on all SPLs. On a regional scale, communities are mainly affected by depth and location. Increasing habitat complexity has significant and positive effects on species richness yet was non-significant for biomass and abundance of the biofouling community. If applied thoughtfully, nature-inclusive design of the SPL habitat, including manipulation of the physical complexity of the structure, can effectively promote biodiversity.

Habitat structural complexity predicts cognitive performance and behaviour inwestern mosquitofish.

Urban stream syndrome alters stream habitat complexity. We define habitat complexity as the degree of variation in physical habitat structure, with increasing variation equating to higher complexity. Habitat complexity affects species composition and shapes animal ecology, physiology, behaviour and cognition. We used a delayed detour test to measure whether cognitive processes (motor self-regulation) and behaviour (risk-taking) of female Western mosquitofish, Gambusia affinis, varied with habitat structural complexity (low, moderate and high) that was quantified visually for nine populations. We predicted that motor self-regulation and risk-taking behaviour would increase with increasing habitat complexity, yet we found support for the opposite. Lower complexity habitats offer less refuge potentially leading to higher predation pressure and selecting for greater risk-taking by fish with higher motor self-regulation. Our findings provide insight into how habitat complexity can shape cognitive processes and behaviour and offers a broader understanding of why some species may tolerate conditions of urbanized environments.

Impact of Cropland Management on Invertebrate Richness and Abundance in Agroforestry Systems in Bali, Indonesia

The intensive management of cropland refers to a reduction in habitat complexity (i.e., shade tree cover, tree species richness, crop species richness) to gain more profits. This usually entails a decrease in biodiversity, but agroforestry systems have been shown to provide a solution to the need for profits while maintaining biodiversity and ecosystem services. Invertebrates are important bioindicators since they are not just affected by a decrease in habitat complexity; they are also key for the maintenance of ecosystems given their ecological roles. We aimed to understand how agricultural intensification impacted invertebrate abundance and richness in an agroforestry system in Bali, Indonesia. We set up 53 × 25 m2 plots and collected data via pitfall and pan traps. We linked those data to vegetation data (canopy cover, tree species richness, crop species richness), habitat type (rustic vs. polyculture), and productivity. Overall, we found that the abundance and richness of invertebrate taxa were positively influenced by increasing canopy cover and crop and tree species richness. This supports the habitat heterogeneity hypothesis, which indicates that increased habitat complexity promotes higher invertebrate species richness and abundance. The abundance and richness of certain invertebrate taxa, including agents of biocontrol, were shown to increase in plots with higher yields, thus solidifying the important role of invertebrate communities in the provision of ecosystem services. Harvesting crops from complex agroforestry systems ensures a sustainable income for local communities as well as habitats for invertebrates.

Vertical optical complexity shaped by submerged macrophytes

The influence of macrophytes on the optical environment of the littoral zone was assessed by studying the effect of monospecific Potamogeton perfoliatus on the quantitative and qualitative properties of light and the response of plants to this altered environment. P. perfoliatus was shown to alter the optical environment and consequently its own architecture: in high-density pondweed patches, 67 percent of incident light was absorbed in the top 10 cm, while spectral properties of light was significantly altered. Leaf morphology and photophysiology adapted to these changes, with photosynthetically active biomass concentrated in the upper water layer and stem biomass increasing in the basal parts due to self-shading. This study highlights the importance of submerged macrophytes in shaping the optical environment and ecological dynamics of littoral zones. Not only do pondweed plants from different sites show very similar vertical patterns of morphological and physiological parameters, but they also contribute to similar vertical spatial variability in water optics, thus increasing habitat complexity. This added optical heterogeneity not only increases the diversity of the littoral zone, but also enriches the entire aquatic ecosystem of shallow lakes by providing additional optical ecological niches.

Changes in vegetation complexity during the development of rice ecosystems affect orb‐weaving spider‐prey trophic networks

Abstract Temporal change in vegetation complexity and field management may interactively affect the structure of predator–prey networks in agroecosystems and consequently alter the biocontrol potential of predators. There is a limited number of studies that have addressed these questions for generalist predator–prey networks. We investigated how vegetation complexity during crop development and management type (conventional vs. organic) affect the trophic networks of orb‐weaving spiders and their prey in rainfed lowland rice ecosystems in southern Thailand. Specifically, we investigated orb‐weaving spiders and prey composition, prey selectivity and network structure. Overall, orb‐weaving spiders captured mostly detritus‐associated Diptera, aquatic‐associated Ephemeroptera and Hemiptera pests. The increasing vegetation complexity during rice development significantly restructured the network of orb‐weaving spiders and prey, while field management had only a marginal effect. The increased vegetation complexity during rice development led to an increased number of weak trophic interactions in comparison to few but strong interactions in simple vegetation. Our results indicate that increasing the number of spider species per prey taxon (prey vulnerability) in late rice season may enhance their top‐down control of prey including rice pests. This study also highlights that the network complexity and the stability of rice ecosystems increased during the rice growing season as the vegetation became more complex. Future practices could look for a way to support the densities of detritus and aquatic insects and to artificially increase habitat complexity during the early stage of rice development to improve the biocontrol services provided by the orb‐weaving spiders.

Flour beetles prefer corners over walls and are slowed down with increasing habitat complexity.

Movement affects all key behaviours in which animals engage, including dispersal and habitat use. The red flour beetle, known as a cosmopolitan pest of stored products, was the subject of our study. We examined whether the beetles preferred corners, walls or open areas, and how turns or obstacles in corridors delayed the beetles' arrival at a target cell. Beetles spent significantly more time in corners than expected by chance, while they spent considerably less time in open areas than expected. However, no significant difference was observed between areas with two or three surrounding walls. This could be attributed to the beetles' stronger attraction to corners than crevices or the insufficient proximity of the third wall to the other two. Movement through the corridor was delayed by turns or obstacles, expressed in arrival probabilities, arrival times, time in the corridor or movement speed. Obstacles on the corridor's perimeter had a stronger effect on the beetle movement than those in the corridor's centre owing to the beetles' tendency to follow walls. The research is important also for applied purposes, such as better understanding beetle movement, how to delay their arrival to new patches, and where to place traps.

Use of epiphyte by bird communities in IPB Dramaga campus

Epiphytes have a direct or indirect influence on terrestrial ecosystems. The presence of epiphytes can increase habitat complexity vertically and benefit animals, especially birds. The objectives of this study were to identify the species of epiphytes, their host trees, and the birds and to analyze how composition of epiphytes and host trees affects the diversity and abundance of birds. The research was conducted in seven sites within the IPB Dramaga Campus from December 2022 to February 2023. We collected biotic data (the number and type of epiphytes, host trees, and birds) and abiotic data (temperature and humidity) at each site. We used Paleontological Statisctic (PAST) to calculate the diversity index and R software to examine the correlation between birds and epiphytes. We found a significant positive correlation between the species richness of epiphytes, host trees, and birds. The sites with the highest diversity and abundance of trees, epiphytes, and birds were Conservation Park and Campus Forest Park. Sites with more diverse and abundant epiphytes had lower temperatures on average. We observed four bird species that used epiphytes: Pycnonotus aurigaster, Aegithina tiphia, Sitta frontalis, and Dicaeum trochileum. These species foraged for invertebrates on or near the Asplenium sp. epiphytes.

“Three-strip management”: introducing a novel mowing method in perennial flower strips and grass margins to increase habitat complexity and attractiveness for pollinators

Flower margins are widely adopted as agri-environment measure (AEM) to enhance farmland biodiversity. However, perennial flower margins need appropriate mowing schemes to manage succession, especially in regions with high nitrogen depositions, and current schemes inadequately address the needs of arthropods, including pollinators. Effective management should provide floral diversity with staggered flowering times, creating varied sward structures for diverse habitats that support shelter, nesting, and mating sites. To address these challenges, a novel mowing method, called 'Three-strip management,' is proposed. This method involves dividing the margin into three strips using curved instead of straight mowing lines. During each cycle, one third remains unmown for shelter, while clippings are removed to lower soil nutrient status and reduce succession. The use of overlapping curved mowing lines aims to maximize variety in patterns, fostering spatio-temporal variation in the (re)growth of perennials and swards. Unlike Regular rotational management, multiple uneven parts are kept unmown over winter, increasing the number of subzones in different mown states over successive years. In this study, field trials comparing Three-strip management with Regular rotational management reveal positive effects especially during the second year, including higher bee abundance and diversity. Plant-pollinator networks also demonstrate increased interactions. While the study focuses on bees, the potential of the Three-strip management to support other beneficial insects is discussed. Given declining insect populations in agricultural landscapes, this paper offers insights into enhancing perennial flower margins as AEM to support pollinator populations. The novel Three-strip management presents a promising strategy for balancing management needs with diverse insect requirements, contributing to sustainable biodiversity conservation in agricultural settings.

Indigenous forest edges increase habitat complexity and refuge opportunities for grassland butterflies

Heterogeneity at local and landscape scales can promote insect diversity and moderate insect declines that stem from global change. Determining how species respond to different landscape components provides insight into the role of heterogeneity in landscapes undergoing change. We examine how indigenous forest-grassland edges are used by butterflies. We assessed butterfly diversity and behaviour at forest edges and adjoining grassland, and tested whether these patterns are influenced by differing weather conditions between seasons. Forest edges supported a species rich butterfly assemblage. Forest specialists were more diverse at forest edges than in grassland, whereas grassland specialists and habitat generalists were as diverse at forest edges as in grassland. All butterfly groups showed more inter- and intra-specific interactions and more patrolling behaviour at forest edges, but more feeding and transient behaviour in grassland. Occurrence and behavioural patterns were not mediated by season, suggesting that the influence of forests does not change with varying environmental conditions. Nonetheless, certain species preferentially utilized forest edges in the hot and windy season, indicating that shelter provided by forest edges influences butterfly habitat use. We found no evidence that complementary nectar sources influence butterfly distribution patterns.Implications for insect conservation: The diverse butterfly assemblages and range of behaviours supported by indigenous forest edges indicate that forest patches are an important habitat component for butterflies. Conserving forest patches in these coastal grasslands may help buffer butterfly populations against global change.

Aquatic connectivity treatments increase fish and macroinvertebrate use of Typha‐invaded Great Lakes coastal wetlands

Abstract Coastal wetlands provide critical habitat for aquatic organisms and important ecosystem services for the terrestrial and aquatic landscapes that they bridge, but increasingly common invasive macrophytes disrupt plant communities, food webs, habitat structure and littoral–pelagic linkages. In Laurentian Great Lakes coastal wetlands, invasive cattails (Typha × glauca and T. angustifolia, hereafter Typha) homogenise ecosystem structure and reduce nearshore dissolved oxygen, and plant, fish and macroinvertebrate diversity. We hypothesised that management treatments which reduce Typha and its abundant litter promote structural heterogeneity and mitigate physicochemical and biodiversity impacts. To test this hypothesis, we implemented a large‐scale (2,048 m2 treatment units), multi‐site (four coastal wetlands) experiment in northern Michigan (U.S.A.) to examine how invasive Typha mechanical harvesting treatments (biomass harvest, aquatic connectivity channels, Typha‐dominated control) altered fish, macroinvertebrate, plant, larval amphibian abundance and diversity, and water quality for 2‐year post‐treatment. Both harvest and channel treatments reduced Typha biomass, cover and dominance; harvest increased multi‐taxa species richness, fish diversity and abundance; and channels altered plant, fish, and macroinvertebrate community structures. Dissolved oxygen was greater and litter was reduced by both treatments, indicating likely mechanisms for shifts in fish and macroinvertebrate use. Our results suggest that harvesting invasive macrophytes can ameliorate biodiversity impacts and improve habitat quality, and that adding aquatic connectivity channels can increase community complexity. Typha management that incorporates both harvesting and aquatic connectivity channels appears to provide the greatest benefit to several taxonomic groups, likely by reducing Typha and its litter, increasing dissolved oxygen availability, and increasing the connection between open water and wetland interiors. Increasing habitat complexity and aquatic connectivity of invaded wetlands can promote biodiversity and provides a more realistic management goal than the complete elimination of invasive macrophytes.

Taxonomic and functional diversity of land snails reflects habitat complexity in riparian forests

Habitat complexity affects the structure and dynamics of ecological communities, more often with increased complexity leading to greater species diversity and abundance. Among the terrestrial invertebrate groups, the low vagility of land snails makes them susceptible to react to small-scale habitat alteration. In the current paper we aimed to assess the relationship between taxonomic and functional composition and diversity of land snail communities and habitat structure in the riparian forest habitat. We found that both snail abundance and species richness responded positively to the increase in habitat complexity. The complexity of the riparian forest affected also the snail trait composition. Forest species, species living in woody debris, leaf litter, and root zone and those feeding on detritus were more abundant in complex habitats, while large snails with more offspring, snails having the ability to survive longer periods of dryness, as well as species that prefer arid habitats, were more abundant in less complex habitats. We concluded that habitat complexity promoted functional diversity, with the amount of woody debris as main positive driver, and the adjacent agricultural fields as negative driver of functional diversity.

Do wave exposure and drifting algae drive the functional diversity of fishes in tropical ocean-exposed sandy beaches?

Tropical ocean-exposed sandy beaches have an essential ecological function for marine fish species, which use these turbulent areas as nurseries. These habitats are characterized as homogeneous environments, but previous studies report the influence of drifting algae in providing physical structure, which increases habitat complexity and heterogeneity. This additional habitat complexity is expected to have a crucial impact on fish assemblages. Here, we analyzed the influences of wave exposure and drifting algae volume on abundance and functional diversity on two beach types: wave-dominated and tide-modified. Beach seine samplings were carried out in the rainy and dry seasons to collect the fish at each beach. Four volume categories of drifting algae were selected: bare sand, low, mid and high. A total of 97 fish species were captured. The community attributes of fishes (abundance, richness and biomass), as well as algal volume, were higher in tide-modified beaches. For abundance, three distinct patterns emerged: 1) there was a trend of decreasing herrings and anchovies compared to other species, from the bare to high-volume drifting algae in tide-modified beaches, with the opposite trend for the wave-dominated beaches; 2) L. breviceps, M. littoralis, S. naso, S. rastrifer and S. stellifer increased in abundance from the bare to high drifting algae in wave-dominated beaches; 3) P. virginicus was abundant in both beach types. These trends were accompanied by functional diversity, principally by responses in the two types of traits: diet and habitat use. The differences in habitat characteristics (wave exposure and drifting algae) among beaches affected the composition and functional diversity and consequently supported distinct fish assemblages. The presence of drifting algae in this habitat favors the attractiveness for fishes, such as larvae and juveniles, and seems to drive habitat use by tropical fishes.

Intertidal habitat complexity influences the density of the non-native crab Hemigrapsus sanguineus.

Habitat structural complexity can provide protection from predators, potentially affecting population density of native and non-native prey. The invasive Asian shore crab, Hemigrapsus sanguineus, occurs in variable densities in the rocky intertidal zone of eastern North America and northern Europe, often in densities greater than in its native range. The present study examined the influence of habitat complexity on the density of H. sanguineus. Artificial shelters of concrete pavers with stones arranged in increasing complexity were deployed in the intertidal zone along a rocky shore in southeastern Massachusetts, USA, for 21 consecutive weekly intervals in 2020. Crabs consistently reached the highest densities in the most complex shelters despite their lower internal surface area. In addition, crabs exhibited shelter selectivity based on body size, with large crabs occupying artificial shelters in greater numbers than adjacent natural substrate. In a subsequent lab study, crab activity over 1 h was observed in the presence of the same artificial shelters, under simulated tidal conditions. Shelter complexity had little influence on the number of crabs under the pavers although crabs were more active when submerged in water than exposed to air. These results show that crab density increases as habitat complexity increases, and complexity may serve as a predictor of H. sanguineus density but not short-term behavior.

Rock outcrops enhance abyssal benthic biodiversity

Abyssal polymetallic nodule fields represent a unique deep-sea habitat. The hard substratum provided by nodules is thought to increase habitat complexity, promoting the occurrence of highly diverse abyssal assemblages. However, hard substratum in these habitats is also available as outcropping rock fragments, but their contribution to habitat heterogeneity has been largely overlooked. Here, we assessed if the type and size of hard substratum can modulate benthic biodiversity at local scales within the Clarion Clipperton Zone (N Pacific abyss). We compared megafauna (animals >10 mm) assemblages in nodule bearing habitats with those in areas containing rocks in addition to nodules. We found a lower faunal density but a clearly higher diversity and more heterogenous composition in the assemblages of rock bearing areas compared to those with only nodules. In addition, hard substratum patch size appeared to positively influence the size of some taxa, like bamboo corals. These results suggest that rocks, in addition to nodules, constitute keystone structures enhancing habitat heterogeneity at local scales within nodule fields. Rock areas appear common in some abyssal plains and may make regionally-important contributions to abyssal biodiversity, suggesting that they may be relevant to include in conservation efforts.

Physical and biogenic complexity mediates ecosystem functions in urban sessile marine communities

AbstractThe influence of habitat complexity on biodiversity is a central theme in ecology, with many studies reporting positive relationships. Reconciliation approaches in urbanised areas, such as eco‐engineering, have increasingly focused on ‘re‐building’ the complexity of degraded and/or homogenised habitats to support biodiversity. Yet, the effects of increasing complexity and biodiversity on ecological functions are rarely measured.We assessed how increasing the physical and/or biogenic complexity of habitats affects the net primary productivity (NPP) and gross primary productivity (GPP), community respiration and nutrient cycling (specifically dissolved inorganic phosphorus and nitrogen) of intertidal sessile marine communities at three sites. We manipulated physical complexity using two types of settlement tiles: ‘complex’, with crevices and ridges, and ‘flat’. We increased biogenic complexity on half the replicates of each tile type by seeding with oysters.Increased physical and biogenic complexity resulted in greater sessile species richness at all sites. Although many variables assessed varied with sites and time of measurements, overall, GPP and NPP were greater on flat tiles than on complex ones. These patterns were not explained by differences in the total surface area of tiles.Daily flux rates of dissolved inorganic phosphorus had a significant positive relationship with biogenic complexity. There were no effects of biogenic or physical complexity on the net fluxes of dissolved inorganic nitrogen.Effects of habitat complexity on the productivity and nutrient cycling of marine sessile communities were largely unrelated to diversity measures, such as richness or abundance of key taxa and functional groups.Synthesis and applications. Eco‐engineering practices that manipulate habitat complexity might benefit from explicit functional targets that also consider associated ecosystem services, as we found that under some conditions there is a trade‐off between biodiversity and functional targets. Our results suggest that increasing habitat complexity has a positive effect on sessile species richness, but not necessarily on productivity (GPP and NPP). The species pool available as well as light availability is likely to mediate effects of complexity on assemblages, so local environment needs to be a key consideration when designing interventions.

Increased food availability at offshore wind farms affects trophic ecology of plaice Pleuronectes platessa

Offshore wind farms (OWFs) and their associated cables, foundations and scour protection are often constructed in soft-sediment environments. This introduction of hard substrate has been shown to have similar effects as artificial reefs by providing food resources and offering increased habitat complexity, thereby aggregating fish around the turbines and foundations. However, as most studies have focused their efforts on fish species that are typically associated with reef structures, knowledge on how soft sediment species are affected by OWFs is still largely lacking. In this study, we analysed the trophic ecology and condition of plaice, a flatfish species of commercial interest, in relation to a Belgian OWF. The combination of a stomach and intestine content analysis with the use of biomarkers (i.e. fatty acids and stable isotopes) identified a clear shift in diet with increased occurrences of typical hard-substrate prey species for fish in the vicinity of the foundations and this both on the short and the long term. Despite some condition indices suggesting that the hard substrate provides increased food availability, no clear increases of overall plaice condition or fecundity were found. Samples from within the wind farm, however, contained larger fish and had a higher abundance of females compared to control areas, potentially indicating a refuge effect caused by the cessation of fisheries activities within the OWF. These results suggest that soft-sediment species can potentially benefit from the presence of an OWF, which could lead to fish production. However, more research is still needed to further elucidate the behavioral ecology of plaice within OWFs to make inferences on how they can impact fish populations on a larger spatial scale.

The Effectiveness of Providing Shell Substrate for the Restoration of Adult Mussel Reefs

Providing benthic substrate is the most common method used for oyster reef restoration. The physical relief from the seabed, increased habitat complexity, and attachment surfaces have been shown to improve oyster health, recruitment, and survival. While the addition of shell material is an effective substrate for oyster restoration, its usefulness in mussel restoration has been understudied. This study tested the effectiveness of adding shell substrate to two different types of soft sediment for the restoration of adult green-lipped mussels. Over 10 t of shell was used to create a 10 cm layer on the seabed in replicated experimental plots at the two locations. 10 t of live adult mussels were deployed onto the shell substrate and an additional 10 t of mussels onto adjacent soft sediment control plots. A year after deploying the live mussels, mussel survival across all plots was 80.6 ± 6.5%, with no differences between mussel plots with or without the added shell substrate for either of the two locations. This study emphasizes the importance of context-dependency, revealing promising avenues for future research, and indicates that for adult green-lipped mussels the addition of a shell substrate appears to provide little advantage for adult mussel restoration at high deployment densities.

The effect of small-scale habitat features on groundfish density in deep-sea soft-bottom ecosystems

In the deep-sea, cold-water corals (CWCs) and other structure-forming fauna locally increase habitat complexity and are host to many fish species. While many studies have focused on hard-bottom CWCs, very little is known about fish associations with soft-bottom CWC habitats. To understand the small-scale linkages between fish, benthic and non-bio-structural habitats in a soft-sediment deep-sea environment, we analysed remotely operated vehicle (ROV) survey videos and recorded the occurrence of fish, invertebrate habitat-forming species and substratum along transects, in the Laurentian Channel Marine Protected Area (MPA) in the Canadian Northwest Atlantic. Almost 13,300 individual fish were recorded, of which all but 65 specimens were identified to family or lower taxonomic rank. The five numerically dominant fish taxa were Redfish (Sebastes spp.), Witch Flounder (Glyptocephalus cynoglossus), Marlin-Spike Grenadier (Nezumia bairdii), Longfin Hake (Phycis chesteri) and one Teleostei morphotype. Teleostei sp1 represents three fish genera (Sandlance (Ammodytes spp.) and two Barracudinas (Arctozenus sp. and Paralepis spp.)) morphologically difficult to differentiate on video footage. Multivariate analysis revealed four habitats based on epibenthic invertebrate densities and diversity. These were dominated by various combinations of sea anemones (Actiniaria), nephtheid soft coral, solitary cup corals (Scleractinia) and three taxa of sea pen (Pennatula spp., Kophobelemnon sp. and Anthoptilum spp.). Univariate analyses performed on dominant fish densities revealed the local influence of hard-bottom substrates and the common influence of soft-sediment micro-features for three fish taxa. All fish densities were correlated with invertebrate density, negatively for Redfish and positively for all other taxa. Our models also predicted the association of four fish taxa with one to two benthic habitats within their preferred depth range. Our results suggest that small-scale habitat heterogeneity in a low relief soft-sediment environment, provided by both physical and biological structures, has a measurable species-specific influence on fish communities. This influence was weaker than typical fish-habitat relationships found in hard-bottom systems, suggesting fish-invertebrate relationships are not obligate. Additionally, we provided evidence that Redfish continue occupying sea pen habitats months after spawning. Our study supports the necessity to continue monitoring the MPA using in-situ video systems to understand the links between fish and habitats in the Laurentian Channel.

Disturbance of plateau zokor (Eospalax baileyi) mounds increase plant and soil macroinvertebrate richness by offering a diversified microenvironment

Habitat heterogeneity is expected to change community composition and diversity, with large implications for ecosystem processes and function. Understanding the potential mechanisms of habitat heterogeneity affecting community ecological processes is a central issue in biodiversity conservation. In this study, we use a spatial metrics analysis to quantify the spatial pattern of plateau zokor mounds. We integrated soil physicochemical variables and community characteristic data to understand the disturbance effect of plateau zokor mounds on community diversity at a microhabitat scale (400 m2). Results showed that plant species richness increased significantly with increasing disturbance levels. Increases in forb species were largely the reason for the increased plant diversity in the alpine meadow disturbed by plateau zokor mounds. Disturbance caused by the plateau zokor significantly increased the soil macroinvertebrate richness and abundance, with herbivorous taxa playing a key role. Mantel tests and redundancy analysis showed that the composition of plant and soil macroinvertebrate communities are significantly related to soil moisture and soil temperature, and the SEM model revealing soil moisture and soil temperature positive effects on plant and macroinvertebrate richness after plateau zokor disturbance. Furthermore, soil variables (moisture, temperature, and organic carbon) directly affected plant richness, and indirectly affected soil macroinvertebrate communities. Our results suggest that the spatial pattern of plateau zokor mounds facilitate greater biodiversity through increased habitat complexity and heterogeneity. Therefore, it can be regarded as a “key species” in the alpine grassland and researchers should pay more attention to the ecological effects of alpine rodent disturbance on grassland ecosystems.