Mobile Invertebrates Research Articles

Soil Macroinvertebrate Presence Alters Microbial Community Composition and Activity in the Rhizosphere.

Despite decades of research, our understanding of the importance of invertebrates for soil biogeochemical processes remains incomplete. This is especially true when considering soil invertebrate effects mediated through their interactions with soil microbes. The aim of this study was to elucidate how soil macroinvertebrates affect soil microbial community composition and function within the root zone of a managed grass system. We conducted a 2-year field mesocosm study in which soil macroinvertebrate communities were manipulated through size-based exclusion and tracked changes in microbial community composition, diversity, biomass and activity to quantify macroinvertebrate-driven effects on microbial communities and their functions within the rhizosphere. The presence of soil macroinvertebrates created distinct microbial communities and altered both microbial biomass and function. Soil macroinvertebrates increased bacterial diversity and fungal biomass, as well as increased phenol oxidase and glucosidase activities, which are important in the degradation of organic matter. Macroinvertebrates also caused distinct shifts in the relative abundance of different bacterial phyla. Our findings indicate that within the rhizosphere, macroinvertebrates have a stimulatory effect on microbial communities and processes, possibly due to low-intensity microbial grazing or through the dispersal of microbial cells and spores by mobile invertebrates. Our results suggest that macroinvertebrate activity can be an important control on microbially-mediated processes in the rhizosphere such as nitrogen mineralization and soil organic matter formation.

Sun coral invasion of shallow rocky reefs: effects on mobile invertebrate assemblages in Southeastern Brazil

Invasive engineering species impact local biodiversity and ecosystem services as they often change habitat complexity while displacing native species, ultimately altering fundamental processes such as secondary production and the energy flow through trophic levels. The sun corals Tubastraea coccinea and T. tagusensis have successfully invaded reef habitats along the Brazilian coast, drastically reducing the diversity of benthic fouling invertebrates and macroalgae at places where colonies had taken large fractions of the available space. Yet, there is no consistent information on the effects of this invasion on assemblages of mobile invertebrates. We sampled shallow vertical reef areas at Buzios Island, SP, Brazil, and compared univariate and multivariate attributes of these assemblages at different levels of sun-coral cover (no cover, half and full cover), at two sites separated by a few km, and two areas within sites separated by several tens of meters. Consistent declines of overall abundance and biomass with increasing coral cover were found at one sampled site, while richness responded only to small-scale heterogeneity with no sun-coral effects. Changes in assemblage structure were area-specific, but similarity analyses most often grouped no coral and half coral cover, leaving aside full coral plots. Tanaids, ostracods and harpacticoid copepods were among the most important groups where sun corals were absent or covering only half of the reef habitat. However, these groups became almost absent in coral saturated habitats. Polychaetes also contributed substantially to dissimilarities, but effects on this group were less clear. Overall, results suggest a negative tipping point between partial to nearly full coral cover, especially at sites where physically complex macroalgae, capable to retain sediments and hence the invertebrates therein, are displaced by the establishment and growth of sun-coral colonies. As important prey for reef fishes, the collapse of small crustacean populations may alter whole-reef ecosystem functioning and negatively impact local fisheries.

Wave energy drives biotic patterns beyond the surf zone: Factors influencing abundance and occurrence of mobile fauna adjacent to subtropical beaches

Management of beach ecosystems often focuses on geomorphic and socio-economic issues. Yet understanding patterns and processes affecting fishes and invertebrates in this dynamic inshore environment will better inform ecosystem management. We used Baited Remote Underwater Video (BRUVs) to survey fish and mobile invertebrate assemblages immediately beyond the surf zone (in 5–8 m depth) across 12 beaches of varying energy and geomorphology, to assess drivers of abundance and occurrence. These beaches in subtropical eastern Australia were categorised based on various morphological, energy, connectivity and management characteristics. Characteristics associated with wave energy (aspect, exposure, modal value) were the strongest drivers of assemblages and functional groups overall. Patterns were strongest for crabs, with high relative abundance of Diogenid crabs (hermit crabs) at low energy beaches, and high relative abundance of Matutid crabs (moon crabs) at higher energy beaches. Bony fish and elasmobranchs were also predominantly influenced by energy characteristics, but these patterns were highly variable. This habitat beyond the surf zone was richer in species relative to adjacent deeper unconsolidated habitats, especially for elasmobranchs. It included target fished species and was a juvenile nursery for several Carangid species. These patterns and values should be considered when management actions are undertaken.

Loss of foundation species: disturbance frequency outweighs severity in structuring kelp forest communities.

Disturbances often cause the disproportionate loss of foundation species but understanding how the frequency and severity of disturbance to such organisms influence biological communities remains unresolved. This gap in knowledge exists in part because of the rarity of ecologically meaningful studies capable of disentangling different elements of disturbance. Hence, we carried out a long-term (9yr), large-scale (2,000m2 plots), spatially replicated (4 sites) field experiment in which we manipulated disturbance to a globally distributed marine foundation species, the giant kelp Macrocystis pyrifera, and tracked community responses over time. To distinguish the effects of disturbance frequency and severity on the biodiversity and composition of temperate rocky reef communities, we simulated the repeated loss of giant kelp from destructive winter waves across a background of natural variation in disturbance. By following the response of over 200 taxa from the surrounding community, we discovered that the frequency of disturbance to giant kelp changed the biomass, diversity, and composition of community guilds in a manner commensurate with their dependence on the physical (i.e., benthic light and space), trophic (i.e., living and detrital biomass), and habitat (i.e., biogenic structure) resources mediated by this foundation species. Annual winter disturbance to giant kelp reduced living and detrital giant kelp biomass by 57% and 40%, respectively, enhanced bottom light by 22%, and halved the seafloor area covered by giant kelp holdfasts. Concomitantly, the biomass of understory algae and epilithic sessile invertebrates more than doubled, while the biomass of rock-boring clams, mobile invertebrates, and fishes decreased 30-61%. Frequent loss of giant kelp boosted understory algal richness by 82% and lowered sessile invertebrate richness by 13% but did not affect the biodiversity of mobile fauna. In contrast to changes driven by disturbance frequency, interannual variation in the severity of disturbance to giant kelp had weaker, less consistent effects, causing only modest changes in assemblages of sessile invertebrates, mobile invertebrate herbivores, and fishes. Our results broaden the foundation species concept by demonstrating that repeated disturbance to a dominant habitat-forming species can outweigh the influence of less frequent but severe disturbances for the surrounding community.

Seasonal changes in taxon richness and abundance of mobile invertebrates inhabiting holdfast of annual kelp Ecklonia radicosa (Phaeophyceae, Lessoniaceae) at the central Pacific coast of Japan

SUMMARYTo investigate seasonal changes in the taxon richness and abundance of mobile invertebrates inhabiting holdfasts of the warm temperate annual kelp Ecklonia radicosa, five holdfasts were collected monthly at the central Pacific coast of Japan from April to November 2014. During the study period, there was little variation in holdfast height and diameter, which ranged from 5.9 to 8.5 cm and from 7.1 to 10.8 cm, respectively. In total 7087 animals were collected from 40 holdfasts (177.2 individuals inds./holdfast, on average). The number of mobile invertebrates gradually increased from May (15 ± 9.9 inds./holdfast) to August (346 ± 152.5 inds./holdfast), with over 300 inds./holdfast until October before rapidly decreasing in November (110 ± 85.6 inds./holdfast). Similarly, taxon richness increased gradually from April (4.3 ± 1.0 taxa/holdfast) to August (11.0 ± 3.7 taxa/holdfast), and decreased in November (8.6 ± 2.3 taxa/holdfast). Interestingly, hundreds of mobile invertebrates inhabited holdfasts of kelp plants that had shed their blade in October and November. Taxon composition from August to October and the number of invertebrates from July to November were comparable to data previously reported for perennial kelps. In this study, the importance of annual Ecklonian species as biogenic habitats was demonstrated for the first time.

Modified kelp seasonality and invertebrate diversity where an invasive kelp co-occurs with native mussels

Non-native species have invaded coastal systems worldwide, altering community structures and ecosystem functioning. One of the most widely distributed marine invaders is the kelp Undaria pinnatifida. In Australasia, Undaria is a large annual kelp that typically has a unimodal growth pattern characterized by high cover during late-winter and spring. It is possible that Undaria co-occurs with mussels and impacts the biodiversity of mussel assemblages on rocky reefs, especially given its presence on mussel farms. Here, we tested whether Undaria and mussels co-occurred on rocky reefs at different temporal and spatial scales, and whether Undaria affects the diversity of mussel-associated small mobile invertebrates. Analyses of survey data showed that individuals of Undaria are often attached to, or interspersed around, mussel aggregations in the low intertidal zone where Undaria was found at similar abundances in its typical winter growth and summer senescence seasons. We hypothesize that this unexpected pattern is caused by overlapping generations coupled with longer growing seasons, potentially triggered by localized higher wave action, rather than individual plants persisting for an entire year. Analyses of Undaria holdfasts and non-living mimics of Undaria holdfasts, showed that live and large holdfasts, in particular, alter and increase small-scale diversity of mobile invertebrates where Undaria co-occurs with mussels. We conclude that Undaria has a longer temporal presence where it co-occurs with mussels and that Undaria alter mussel-associated communities of small mobile invertebrates.

Effects of depth on reef fish communities: Insights of a “deep refuge hypothesis” from Southwestern Atlantic reefs

Deeper reefs are often considered to be less susceptible to local and global disturbances, such as overfishing, pollution and climate change, compared to shallow reefs and therefore could act as refugia for shallow water species. Hence, the interest on deeper reefs has happened at a time when shallow reefs are undergoing unprecedented changes. Here we investigated the hypothesis that fish community differed from shallow to deeper reefs due to factors apart from habitat structure and quality and therefore discuss for the first-time insights of a “deep refuge hypothesis” from Brazilian reefs. We collected data on fish community, benthic community and physiological conditions of two coral species on shallow (< 6 m) and deep reefs (> 25 m). No significant difference on substratum composition was observed comparing sites and depths. Additionally, physiological data on corals also showed similar oxidative status and growth conditions when comparing the two-coral species in shallow and deep reefs. Conversely, our study demonstrated strong differences on reef fish communities in terms of abundance, species richness, trophic groups, size classes and groups of interest when comparing shallow and deeper reefs. Fish abundance was 2-fold higher and species richness was up to 70% higher on deeper reefs. Also, a significant difference was observed comparing trophic groups of reef fish. Macrocarnivore, Mobile invertebrate feeders, Planktivores, Sessile Invertebrates Feeders and Roving Herbivores were more abundant on deeper reefs. On the other hand, Territorialist Herbivores almost exclusively dominated shallow reefs. Strong differences were also observed comparing the abundance of reef fish groups of interest and their respective size classes between shallow and deeper reefs. Ornamental, Great Herbivores and Groupers showed clear differences, with higher abundances being observed in deeper reefs. Considering size classes, larger individuals (> 15 cm) of Great Herbivores, Groupers and Snapper were uniquely recorded at deeper reefs. Additionally, individuals with > 30 cm were recorded almost exclusively on deeper reefs for all the analyzed groups of interest. Our findings suggest that fishing pressure on the target species may be attenuated on deeper reefs, and these regions may therefore be considered as areas of refuge from shallow water impacts. Therefore, the likely potential for deeper reefs protect species from natural or anthropogenic disturbances increases the attention of marine conservation planning and resource management on including deeper reefs in protected areas.

Ecosystem restructuring along the Great Barrier Reef following mass coral bleaching.

Global warming is markedly changing diverse coral reef ecosystems through an increasing frequency and magnitude of mass bleaching events1-3. How local impacts scale up across affected regions depends on numerous factors, including patchiness in coral mortality, metabolic effects of extreme temperatures on populations of reef-dwelling species4 and interactions between taxa. Here we use data from before and after the 2016 mass bleaching event to evaluate ecological changes in corals, algae, fishes and mobile invertebrates at 186 sites along the full latitudinal span of the Great Barrier Reef and western Coral Sea. One year after the bleaching event, reductions in live coral cover of up to 51% were observed on surveyed reefs that experienced extreme temperatures; however, regional patterns of coral mortality were patchy. Consistent declines in coral-feeding fishes were evident at the most heavily affected reefs, whereas few other short-term responses of reef fishes and invertebrates could be attributed directly to changes in coral cover. Nevertheless, substantial region-wide ecological changes occurred that were mostly independent of coral loss, and instead appeared to be linked directly to sea temperatures. Community-wide trophic restructuring was evident, with weakening of strong pre-existing latitudinal gradients in the diversity of fishes, invertebrates and their functional groups. In particular, fishes that scrape algae from reef surfaces, which are considered to be important for recovery after bleaching2, declined on northern reefs, whereas other herbivorous groups increased on southern reefs. The full impact of the 2016 bleaching event may not be realized until dead corals erode during the next decade5,6. However, our short-term observations suggest that the recovery processes, and the ultimate scale of impact, are affected by functional changes in communities, which in turn depend on the thermal affinities of local reef-associated fauna. Such changes will vary geographically, and may be particularly acute at locations where many fishes and invertebrates are close to their thermal distribution limits7.

Globally discordant Isocrinida (Crinoidea) migration confirms asynchronous Marine Mesozoic Revolution

The Marine Mesozoic Revolution (MMR, starting ~200 million years ago) changed the ecological structure of sea floor communities due to increased predation pressure. It was thought to have caused the migration of less mobile invertebrates, such as stalked isocrinid crinoids, into deeper marine environments by the end of the Mesozoic. Recent studies questioned this hypothesis, suggesting the MMR was globally asynchronous. Alternatively, Cenozoic occurrences from Antarctica and South America were described as retrograde reversions to Palaeozoic type communities in cool water. Our results provide conclusive evidence that isocrinid migration from shallow to deep water did not occur at the same time all over the world. The description of a substantial new fauna from Antarctica and Australia, from often-overlooked isolated columnals and articulated crinoids, in addition to the first compilation to our knowledge of Cenozoic Southern Hemisphere isocrinid data, demonstrates a continuous record of shallow marine isocrinids from the Cretaceous-Paleogene to the Eocene/Oligocene boundary.

Oceanographic and biological influences on recruitment of benthic invertebrates to hard substrata on the Oregon shelf

The number of anthropogenic substrata in the ocean – structures like oil rigs and offshore renewable energy generators – is increasing. These structures provide hard-bottom habitat in areas previously dominated by sand or mud, so they have the potential to alter species distributions or serve as “stepping-stones” between other hard-bottom habitats. It is thus important to understand what factors influence the composition and abundance of benthic fauna recruiting at these sites. We examined recruitment to hard substrata (fouling panels) deployed on sand at various distances from a large rocky reef (∼60 m isobath) on the southern Oregon coast in 2014–2015. Recruitment was dominated by the acorn barnacle Hesperibalanus hesperius. For the majority of the study period in 2014, an anti-cyclonic eddy was present near the deployment sites. However, anomalously high recruitment of H. hesperius during August – early October 2014 coincided with dissipation of the eddy, slower bottom currents, and a positive convergence index, suggesting that H. hesperius larvae from the adjacent area may have been accumulated and retained near our study sites. Other sessile species, including hydroids and bryozoans, recruited to the fouling panels in low abundances, and most of these species have long-range dispersal and fast growth. Mobile invertebrates observed on the fouling panels included gastropods and nudibranchs, most of which also have long-range dispersal and fast growth, and are predators as adults. Thus, a community with two trophic levels assembled on the fouling panels in a relatively short time period (<12 weeks). None of the common hard-bottom species from the adjacent rocky reef recruited to the panels, suggesting that there is a specialized assemblage of species that can exploit hard-bottom habitats surrounded by sandy plains. Our results raise many questions about the influences of dispersal and oceanographic conditions on recruitment to hard substrata.

Corrigendum

Corrigendum

Rocky reef fish assemblage structure in coastal islands of southern Brazil

Within the Brazilian province, rocky reefs and submerged outcrops are among the most important habitats for reef fishes, providing suitable habitats for the development of reef fish communities and consequently sheltering a high ecological diversity. Rocky reef fish assemblages were sampled in seven coastal islands in South Brazil by strip transects of 40 m 2 by the underwater visual census to obtain density (fish 40 m -2 ) and biomass (g 40 m -2 ). Fish species were also categorized according to trophic category and geographical distribution. In total, 526 strip transects were performed, covering an area of 21,040 m 2 , providing 19,377 fish, distributed among 73 species of 34 families. Itacolomis Island presented the highest density, followed by Veado Island. Regarding biomass, Itacolomis Island and Pedra da Baleia were the most representative rocky reefs. Mobile invertebrate predator was the trophic category with the highest density and biomass. A total of 60% of the species occur in the Western Atlantic, 20% are Transatlantic and 9.6% are endemic to the Brazilian Province. Our results indicate that despite the similarity in the taxonomic composition among islands, the observed differences in densities and biomass, highlight singular assemblage structures, whether by environmental and/or anthropogenic factors, and dominated by few species, both in density and biomass.

Ecosystem health in coastal areas targeted by small-scale artisanal fisheries: Insights on monitoring and assessment

The assessment of the status of marine ecosystems is still a major challenge, because in general we lack well-established ecosystem-based monitoring programs. The coast of central Chile is subjected to moderate but historic fishing pressure by small-scale fisheries. In spite of the increasing evidences of the impact of fishing beyond target species, there is a lack of systematic ecosystem-based assessments. We focused on this problem with the goal of identifying community components, based on a Biological Traits Analysis, that respond to fishing activities to ultimately define ecosystem health. We sampled a set of study sites subjected to benthic invertebrate gathering, and more recently to kelp harvesting. Sites included paired fishery restricted and open access areas where mobile invertebrates and sessile benthos were surveyed. In addition, kelp density and size structure were assessed in two sites subjected to kelp harvesting (also pairing restricted and open access areas). Target species exhibited higher densities in fishery-restricted areas. Fisheries restricted-areas also showed overall higher richness and redundancy of biological traits. Otherwise, we observed high variability in the structure of sessile benthos linked to small-scale heterogeneity of the seabed. The areas subjected to kelp harvesting exhibited variability in mobile invertebrates’ composition between fishing access regimes, whereas no effects could be detected by only considering target species. Current monitoring efforts seem to be well-suited to address target species but fail to inform on ecosystem health in an area with increasing signs of community-wide effects from fishing. Therefore, we recommend future monitoring schemes targeting community components, beyond commercial species’ densities, at different scales.

Mature and developing kelp bed community composition in a glacial estuary

The assembly and maintenance of biological communities is influenced by environmental factors, which are predicted to shift with climate change. Glaciers are melting at increasing rates, delivering sediment and fresh water to coastal habitats. We hypothesized that environmental factors related to glacial discharge would be correlated to the initial recruitment and colonization of sessile communities in kelp beds, and to the abundance of mobile epibenthic invertebrates and adult kelp. To test these hypotheses, cleared rocks were placed at six sites at 10-m depth across a gradient of glacial-influence in Kachemak Bay, Alaska and the percent cover of the initial recruitment and the subsequent progression of the sessile community was monitored over 18months. Small mobile invertebrates (such as limpets and chitons) were also monitored on these rocks for 18months. Lastly, larger invertebrates (such as sea stars) and adult kelp were surveyed over the same time period along transects in the immediate vicinity of the cleared rocks. Environmental factors (sedimentation rates, salinity, temperature, irradiance, and nutrient concentration) were concurrently monitored at each site. Recruitment and subsequent colonization varied along the glacial gradient. At sites with higher sedimentation rates, recruitment and the subsequent developing community was dominated by barnacles with little or no kelp recruits and other macroalgae and high temporal variation in availability of bare space. At more oceanic sites, these communities were characterized by a slow increase in cover of encrusting and upright macroalgae, also with high variability among sites. Mobile invertebrates and adult kelp were more abundant at oceanic sites than the glacial sites. Using distance-based linear models, inorganic sedimentation rate was correlated to patterns of kelp bed recruitment and colonization and to the abundance of mobile invertebrates and adult kelps in the surrounding area. Changes in inorganic sedimentation with climate change may alter how kelp beds are distributed and structured in glacial estuaries.

Food Web Structure and Trophic Relations in a Riverine Mangrove System of the Tropical Eastern Pacific, Central Coast of Colombia

The isotopic composition of carbon and nitrogen of sources and consumers and the mixing model stable isotope analysis in R (SIAR) were used to understand the trophic structure to identify the main carbon sources in the food web of a highly humid riverine mangrove system on the Pacific coast of Colombia. The δ13C values of carbon sources varied from − 30.6 to − 26.9‰. Consumers were separated into invertebrates (with δ13C mean values from − 24.8 ± 0.3‰ to − 15.7 ± 0.7‰) and fish (with δ13C mean values from − 21.2 ± 1.3‰ to − 17.2 ± 0.9‰). Benthic mobile invertebrates generally had depleted δ13C values related to different trophic pathways to those of filter feeders and fish (with more enriched δ13C values). In agreement with similar studies in estuarine macro-tidal areas (e.g., Brazil and Panamanian Pacific), the large range in δ13C values for consumers may indicate that different carbon sources are important for the analyzed food web. In general, fish exhibited greater nitrogen values than invertebrates, indicating higher trophic levels. Among all consumers, with some exceptions, δ15N values correctly reflected the trophic levels, as species from lower trophic levels had lower δ15N than species from higher trophic levels. The trophic length of the food web was estimated from producers to higher consumers based on δ15N values. Taking into account a nitrogen trophic fractionation value of 3.4‰, the studied system exhibited a food web with four trophic levels. Based on the distribution of consumer trophic guilds in the δ13C-δ15N plane and the mixing model results, we recognized that at least two main pathways are present in the system to support the community.

Habitat formation prevails over predation in influencing fouling communities.

Coastal human‐made structures, such as marinas and harbors, are expanding worldwide. Species assemblages described from these artificial habitats are novel relative to natural reefs, particularly in terms of the abundance of nonindigenous species (NIS). Although these fouling assemblages are clearly distinctive, the ecosystem functioning and species interactions taking place there are little understood. For instance, large predators may influence the fouling community development either directly (feeding on sessile fauna) or indirectly (feeding on small predators associated with these assemblages). In addition, by providing refuges, habitat complexity may modify the outcome of species interactions and the extent of biotic resistance (e.g., by increasing the abundance of niche‐specific competitors and predators of NIS). Using experimental settlement panels deployed in the field for 2.5 months, we tested the influence of predation (i.e., caging experiment), artificial structural complexity (i.e., mimics of turf‐forming species), and their interactions (i.e., refuge effects) on the development of sessile and mobile fauna in two marinas. In addition, we tested the role of biotic complexity—arising from the habitat‐forming species that grew on the panels during the trial—on the richness and abundance of mobile fauna. The effect of predation and artificial habitat complexity was negligible, regardless of assemblage status (i.e., native, cryptogenic, and nonindigenous). Conversely, habitat‐forming species and associated epibionts, responsible for biotic complexity, had a significant effect on mobile invertebrates (richness, abundance, and community structure). In particular, the richness and abundance of mobile NIS were positively affected by biotic complexity, with site‐dependent relationships. Altogether, our results indicate that biotic complexity prevails over artificial habitat complexity in determining the distribution of mobile species under low predation pressure. Facilitation of native and non‐native species thus seems to act upon diversity and community development: This process deserves further consideration in models of biotic resistance to invasion in urban marine habitats.

The invasive kelp Undaria pinnatifida hosts an epifaunal assemblage similar to native seaweeds with comparable morphologies

Invasive seaweeds have the potential to disrupt ecosystem functioning if they are unsuitable hosts for the small mobile invertebrates (epifauna) that are an important trophic link between benthic primary producers and higher trophic levels. The Asian kelp Undaria pinnatifida has successfully invaded many coastal regions worldwide. We compared the epifaunal assemblage on U. pinnatifida with epifauna of 7 co-occurring, canopy-forming native brown seaweed species in southern New Zealand to help understand the effect of the invasive species on shallow subtidal ecosystems. The density, diversity and composition of epifauna across the 8 seaweeds were much more strongly related to host morphology than to the geographic origin of the host. U. pinnatifida and several native seaweeds with similarly simple morphologies supported relatively depauperate epifaunal assemblages dominated by copepods. More structurally complex native seaweeds supported more abundant and diverse epifaunal assemblages containing lower proportions of copepods and higher proportions of amphipods and other epifaunal groups. Our results indicate that abundances of epifauna at the ecosystem level will be reduced if U. pinnatifida displaces more structurally complex native seaweed species that host more diverse and dense epifaunal assemblages. The findings suggest that morphological complexity may be key to predicting the impacts of invasive seaweeds on epifaunal assemblages, and potentially on food webs, in other geographic regions.

Gradients in marine biodiversity

Marine Biodiversity Marine animal biodiversity increases severalfold toward the tropics, but a general theory to explain this is lacking. Edgar et al. used extensive global surveys to address this question for fish and mobile invertebrates on rocky reefs over 100° of latitude. Regional diversity was highest near the equator, but local diversity reflected abundances that differed between fish, which peaked in the tropics, and invertebrates, which peaked at higher latitudes. These patterns correlated with temperature gradients for fish and nutrients for invertebrates. Thus, fish appear to have limited the local abundance and diversity of invertebrates in the tropics. Regionally, however, diversity depended strongly on the area of suitable reef habitat, raising alarm about the loss of biodiversity as tropical reefs decline. Sci. Adv. 10.1126/sciadv.1700419 (2017).

Abundance and local-scale processes contribute to multi-phyla gradients in global marine diversity.

Among the most enduring ecological challenges is an integrated theory explaining the latitudinal biodiversity gradient, including discrepancies observed at different spatial scales. Analysis of Reef Life Survey data for 4127 marine species at 2406 coral and rocky sites worldwide confirms that the total ecoregion richness peaks in low latitudes, near +15°N and -15°S. However, although richness at survey sites is maximal near the equator for vertebrates, it peaks at high latitudes for large mobile invertebrates. Site richness for different groups is dependent on abundance, which is in turn correlated with temperature for fishes and nutrients for macroinvertebrates. We suggest that temperature-mediated fish predation and herbivory have constrained mobile macroinvertebrate diversity at the site scale across the tropics. Conversely, at the ecoregion scale, richness responds positively to coral reef area, highlighting potentially huge global biodiversity losses with coral decline. Improved conservation outcomes require management frameworks, informed by hierarchical monitoring, that cover differing site- and regional-scale processes across diverse taxa, including attention to invertebrate species, which appear disproportionately threatened by warming seas.

Seascape architecture – incorporating ecological considerations in design of coastal and marine infrastructure

With nearly 60% of the human population concentrated around the coastlines, alongside growing threats from sea level rise and increased storminess, accelerated coastal development is inevitable. As most marine flora and fauna reside in coastal areas, anthropogenic changes to coastlines are a key reason for loss of coastal habitats, and associated ecosystem services. While coastal infrastructure such as seawalls or breakwaters add significant amounts of hard substrate for marine organisms, they do not support similar species assemblages to those of natural habitats. This is mainly due to design features related to steep slopes, low structural complexity, and high homogeneity, all of which are rarely found in natural habitats. This study provides an example for seascape architecture of coastal structures using ecologically sensitive designs and concrete technologies that enhance the structures’ biological and ecological value while contributing to structural integrity. Four 1.5mx0.8m seawall panels made of bio-enhancing concrete with high structural complexity were deployed in an active marina (Herzliya, Israel). The panels, spanned from the Mean High Higher Water (MHHW) down to the sublittoral zone, were surveyed 2, 7, 12, 18 and 22 months post deployment using 0.3×0.3m quadrats in both intertidal and sublittoral zones of each panel. Bio-enhanced panels were compared to fixed control quadrats comprised of scraped sections of the original concrete marina seawall.Results demonstrated the effectiveness of applying ecological considerations for biological and ecological enhancement of active infrastructure. All community parameters examined (live cover, richness, biodiversity) were significantly higher on bio-enhanced panels compared to controls. Moreover, mobile invertebrates and resident fish species were clearly enhanced through design aspects (holes and crevices) of the bio-enhanced panels. The study provides an example of an emerging approach of assimilating ecological considerations into the design and construction of working waterfronts and active coastal infrastructure, thus reducing their ecological footprint without compromising their operational performance.