Recruitment Of Invertebrates Research Articles

Predation shapes invertebrate diversity in tropical but not temperate seagrass communities.

The hypothesis that biotic interactions are stronger at lower relative to higher latitudes has a rich history, drawing from ecological and evolutionary theory. While this hypothesis suggests that stronger interactions at lower latitudes may contribute to the maintenance of contemporary patterns of diversity, there remain few standardized biogeographic comparisons of community effects of species interactions. Using marine seagrasses as a focal ecosystem of conservation importance and sessile marine invertebrates as model prey, we tested the hypothesis that predation is stronger at lower latitudes and can shape contemporary patterns of prey diversity. To further advance understanding beyond prior studies, we also explored mechanisms that likely underlie a change in interaction outcomes with latitude. Multiple observational and experimental approaches were employed to test for effects of predators, and the mechanisms that may underlie these effects, in seagrass ecosystems of the western Atlantic Ocean spanning 30° of latitude from the temperate zone to the tropics. In predator exclusion experiments conducted in a temperate and a tropical region, predation decreased sessile invertebrate abundance, richness and diversity on both natural and standardized artificial seagrass at tropical but not temperate sites. Further, predation reduced invertebrate richness at both local and regional scales in the tropics. Additional experiments demonstrated that predation reduced invertebrate recruitment in the tropics but not the temperate zone. Finally, direct observations of predators showed higher but variable consumption rates on invertebrates at tropical relative to temperate latitudes. Together, these results demonstrate that strong predation in the tropics can have consequential impacts on prey communities through discrete effects on early life stages as well as longer-term cumulative effects on community structure and diversity. Our detailed experiments also provide some of the first data linking large-scale biogeographic patterns, community-scale interaction outcomes and direct observation of predators in the temperate zone and tropics. Therefore, our results support the hypothesis that predation is stronger in the tropics, but also elucidate some of the causes and consequences of this variation in shaping contemporary patterns of diversity.

Exposure to Waterborne nTiO2 Reduces Fertilization Success and Increases Polyspermy in a Bivalve Mollusc: A Threat to Population Recruitment.

Fertilization success is crucial for the population recruitment of an organism. However, little is known about the threat of nanoparticles (NPs) to the fertilization of broadcast spawners. Therefore, the effects of nTiO2 on fertilization success, polyspermy rate, sperm velocity, gametic DNA damage, sperm-egg collision probability, gamete fusion, and oocyte ultrastructure were investigated in a broadcast spawning bivalve, Tegillarca granosa. The results obtained show that fertilization success significantly decreased, whereas polyspermy risk markedly increased upon nTiO2 exposure. In addition, nTiO2 exposure led to a significant reduction in sperm swimming velocity, which would subsequently constrain gamete collisions. In addition, nTiO2 exposure resulted in a significant decline in gamete fusion per collision along with aggravated DNA damage in gametes. Furthermore, ultrastructural analysis illustrated the attachment of nTiO2 to the oocyte surface, which subsequently resulted in microvillus disassociation and plasma membrane damage. In conclusion, the results obtained suggest a significant threat from NP pollution to the recruitment of broadcast spawning invertebrates.

Aqueous copper bioavailability linked to shipwreck-contaminated reef sediments

Pollution from the grounding or sinking of ships can have long lasting effects on the recovery and dynamics of coastal ecosystems. Research on the impact of copper (Cu) pollution from the 2011 MV Rena shipwreck at the Astrolabe Reef (Otaiti), New Zealand, 5 years after the grounding, followed a multi-method and multi-disciplinary approach. Three independent measures of aqueous Cu using trace-element-clean-techniques substantiate the presence of high total, total dissolved (<2 µm) and elevated bioavailable Cu in the water column immediately above the aft section of the wreck where the highest sedimentary load of Cu was located. Intermittently elevated concentrations of strong Cu-binding ligands occurred in this location, and their binding strength was consistent with ligands actively produced by organisms in response to Cu induced stress. The recruitment of benthic invertebrates was modified at the high-Cu location. Taxonomic groups usually considered robust to pollution were restricted to this site (e.g. barnacles) or were the most abundant taxa present (e.g. foraminifera). Our results demonstrate that Cu-contaminated sediments can impose a persistent point source of Cu pollution in high-energy reef environments, with the potential to modify the composition and recovery of biological communities.

Lower diversity of recruits in coastal reef assemblages are associated with higher sea temperatures in the tropical South Atlantic

Climate change will lead to community shifts and increase the vulnerability of coastal marine ecosystems, but there is yet insufficient detail of how early life stages of marine populations are linked to oceanic-climate dynamics. This study aimed to investigate how ocean-climate variability is associated with spatial and temporal changes in benthic larval recruitment of tropical reef assemblages. Recruitment (abundance, richness, and diversity) of benthic invertebrates was monitored for one year on macroalgal beds in four rocky reefs in a marine protected region in the Eastern coast of Brazil, and compared to fluctuations in meteo-oceanographic conditions at multiple temporal scales (days, weeks, and months). Our results revealed that recruitment of benthic invertebrates varies widely (up to 15 orders of magnitude) among sampled reefs and in time, with wave height, wind speed, and sea temperature being significantly related to recruitment variability. We detected strong taxonomic variability in recruitment success and ocean-climate variables, which highlights the complexity of estimating community vulnerability to climate change in benthic communities. Given that macroalgal beds are key to recruitment of some species regionally (4–30 km), the protection of coastal nursery habitats may be critical for marine conservation and species adaptation in a climate change scenario. Considering the projected ocean-climate change in IPCC scenarios, our study suggests that recruitment of marine populations in coastal reefs could be highly sensitive to climate change in the tropical South Atlantic Ocean.

Functional consumers regulate the effect of availability of subsidy on trophic cascades in the Yellow River Delta, China

Understanding the environmental context where heterogeneous ecological processes affect biotic interactions is a key aim of ecological research. However, mechanisms underlying spatial variation in trophic interactions linked to resource availability across ecosystem gradients remains unclear. We experimentally manipulated the interactive effects of predator fish and quantitative gradient of leaf detritus on macroinvertebrates and benthic algae. We found that non-linear changes in the strength of trophic cascades were strongly linked to the retention rates of experimental leaf detritus and also determined by predatory consumers. Retention rate of leaf detritus influenced the recruitment of predatory invertebrates and foraging preference of predators, accounting for largely the variations in shift of strengthening and weakening trophic cascades. Our results highlight the importance to identify joint processes of recruitment and foraging responses of functional consumer in understanding the impacts of both anthropogenic and natural alterations in subsidy on trophic interaction of coastal food webs.

Do alpine macroinvertebrates recover differently in lakes and rivers after alien fish eradication?

Introduced fish can have detrimental effects on native biota inhabiting alpine freshwaters with the extent of their impact depending on variables such as habitat features. The present study aims to compare the recovery of macroinvertebrate communities following a fish eradication campaign in a mountain lake (Lake Dres, 2087 m a.s.l., Western Italian Alps) and its inflowing and outflowing streams. All fish were removed using mechanical methods, not producing side-effects for macroinvertebrates. During eradication, the lake community, which had previously been greatly affected, rapidly recovered to levels typical of never-stocked lakes. Stream communities, however, were apparently not impacted by fish populations and remained relatively stable, proving their greater capacity to withstand fish presence. The abundance of spatial refugia and invertebrate recruitment (via birth or immigration) can explain the observed stability in stream communities. Drifting macroinvertebrates are often called into question to explain the resistance of stream communities as they can partially offset predation via benthic recruitment, but our results show that stream resistance can be high even where drift is low,i.e., in the outflowing stream.

Temporal variation in invertebrate recruitment on an Eastern Pacific coral reef

The recruitment of marine invertebrate larvae to coral reef ecosystems is critical for the continued productivity of these highly biodiverse habitats. Despite such importance, little is known about temporal variation patterns of invertebrate larval recruitment in coral reefs ecosystems, aside from studies focused only on reef corals themselves. Given this knowledge deficiency, recruitment onto dead coral branches was monitored over a one-year period in the Central Mexican Pacific, and recruit assemblage and density both changed over time. In particular, recruitment was higher in the warmer months, possibly due to reproductive processes and/or increases in metabolic rates associated with high temperatures and seasonal/local events such as upwellings that increase the food resources available for the recruits which just before the warm season, when the recruitment is more more prevalent during the warm season. The most common invertebrate recruits were malacostracans, ostracods, gastropods, maxillopods, and polychaetes, and foraminifers were commonly observed, as well. Future works in this region will seek to understand whether recruit density and diversity change in response to elevated temperatures associated with global climate change.

Polyurethane, epoxy resin and polydimethylsiloxane altered biofilm formation and mussel settlement

In many environments, biofilms are a major mode and an emergent form of microbial life. Biofilms play crucial roles in biogeochemical cycling and invertebrate recruitment in marine environments. However, relatively little is known about how marine biofilms form on different substrata and about how these biofilms impact invertebrate recruitment. Here, we performed a comparative analysis of a 28-day-old biofilm community on non-coated (a control glass) and coated substrata (polyurethane (PU), epoxy resin (EP) and polydimethylsiloxane (PDMS)) and examined the settlement of Mytilus coruscus plantigrades on these biofilms. PU, EP and PDMS deterred the development of marine biofilms by reducing the biofilm biomass including the biofilm dry weight, cell density of the bacteria and diatoms and chlorophyll a concentrations. Further analysis of bacterial community revealed that EP altered the bacterial community composition compared with that on the glass substrata by reducing the relative abundance of Ruegeria (Alphaproteobacteria) and by increasing the relative abundance of Methylotenera (Betaproteobacteria) and Cyanobacteria in the biofilms. However, bacterial communities developed on PU and PDMS, as well as glass and PU, EP and PDMS did not exhibit differences from each other. The M. coruscus settlement rates on biofilms on PU, EP and PDMS were reduced by 20–41% compared with those on the glass after 28 days. Thus, the tested coatings impacted the development of marine biofilms by altering the biofilm biomass and/or the bacterial community composition. The mussel settlements decreased in the biofilms that formed on the coatings compared with those on non-coated glass.

Invertebrate recruitment on artificial substrates in the Red Sea: role of substrate type and orientation

AbstractSurface physical properties, hydrodynamics, biochemical cues, orientation and temporal scales play an important role in invertebrate larval recruitment on artificial substrates. In the present study, invertebrate recruitment on four different substrates (acrylic, stainless steel, ceramic and concrete panels) was investigated in two different orientations (vertical and horizontal) in the central Red Sea. Results showed significant variations in the abundance of benthic invertebrates between the different substrates. While barnacles and bivalves preferred panels placed in vertical positions, the abundance of bryozoans was high on horizontal panels. Artificial panel submersion season plays a significant role in the recruitment of benthic invertebrates on surfaces in the Red Sea. In conclusion, this study supports the overall notion that marine invertebrate recruitment on hard substrates is regulated by a combination of factors which include substrate type, orientation and submersion season.

First large-scale ecological impact study of desalination outfall reveals trade-offs in effects of hypersalinity and hydrodynamics

Desalination is an increasingly common method of meeting potable water demands, but the associated ecological risks are not well understood. Seawater desalination plants discharge large volumes of hypersaline brine directly into the ocean, raising concerns about potential impacts to marine life. In order to reduce impacts of brine, newer desalination outfalls are often fitted with high-pressure diffusers that discharge brine at high velocity into the water column, increasing the mixing and dilution of brine with ocean water. However, there are few published studies of marine impacts of desalination brine, and no well replicated before-after designs. Here we report a six-year study testing for impacts and subsequent recovery of sessile marine invertebrate recruitment near a desalination outfall with high-pressure diffusers. We used a Multiple Before-After-Control-Impact (MBACI) design to test for impacts and recovery at two distances (30 m and 100 m) from a 250 ML/day plant outfall, as well as a gradient design to test the strength of impacts relative to distance from the outfall. The diffusers achieved the target of less than 1 psμ salinity difference to surrounding ambient waters within 100 m of the discharge outfall, but sessile invertebrates were nonetheless impacted. Polychaetes, bryozoans and sponges reduced in cover as far as 100 m from the outfall, while barnacles showed the opposite pattern and were more abundant near the discharging outfall. Ecological impacts were disproportionate to the relatively minor change in salinity (∼1 psμ), suggesting a mechanism other than salinity. We propose that impacts were primarily driven by changes in hydrodynamics caused by the diffusers, such as higher near-bed flow away from the outfall. This is consistent with flow preferences of various taxonomic groups, which differ due to differences in settlement and feeding abilities. High-pressure diffusers designed to reduce impacts of hypersalinity may inadvertently cause impacts through hydrodynamics, leading to a trade-off in minimizing combined salinity and hydrodynamic stress. This study provides the first before-after test of ecological impacts of desalination brine on sessile marine communities, and rare insight into mechanisms behind impacts of a growing form of human disturbance.

Trophic environments influence size at metamorphosis and recruitment performance of Pacific oysters

Reproduction and recruitment of benthic invertebrates are influenced by the climate and by the ecological structure of marine ecosystems, along with local anthropogenic pressures such as eutrophication or oligotrophication. Using the Pacific oyster Crassostrea gigas as a biological model, we tested the hypothesis that the variability in prodissoconch II (PII) size (i.e. size at metamorphosis) depends on ecological functioning. Settlement and recruitment were assessed at 5 sampling sites on the French Mediterranean shellfish farmed Thau lagoon during the main summer recruitment events in 3 consecutive years (2012-2014). Hydrobiological and planktonic analyses were conducted at 3 sampling sites. Our results showed that recruitment was extremely heterogeneous, ranging from 0 to 260 +/- 27 SE ind. dm(-2) throughout the ecosystem and was linked with variability in PII size, which ranged from 180 to 296 mu m. The annual temporal pattern of PII sizes appeared to be controlled by temperature during the settlement period, whereas the spatial pattern depended on phytoplankton biomass and on the trophic functioning of the ecosystem. Smaller PII sizes were significantly correlated with the highest phytoplankton biomass, while larger PII sizes were positively correlated with mixotrophic cryptophyte abundance. We found an inverse relationship between PII size and survival after metamorphosis, showing that recruitment success was associated with smaller PII sizes. Regional climate conditions and local trophic functioning appear to be key factors in metamorphosis and consequently contribute to recruitment heterogeneity. Further studies should be performed in other ecosystems following an oligotrophication trajectory to generalize this result.

Disentangling settlement responses to nutrient-rich contaminants: Elevated nutrients impact marine invertebrate recruitment via water-borne and substrate-bound cues

Anthropogenic contaminants, including nutrient enrichment, frequently alter environmental conditions in marine systems and affect the development of communities on hard-substrata. Biofilms can influence the settlement of marine invertebrates and hence impact on the structure of fouling communities. Few studies have examined bacteria, invertebrates and nutrient-rich contaminants in concert, with none yet to examine the effects of nutrient-rich contaminants on both biofilms and the recruitment of sessile invertebrate communities in-situ to ascertain the mechanistic basis behind observed impacts. Biofilm treatments were allowed to develop under manipulated environmental conditions of either ambient or enriched nutrient levels. Enrichment conditions were elevated via slow-release fertiliser and invertebrate recruitment was prevented during initial biofilm development. Biofilm treatments (including a no film control) were then subject to either ambient or enriched water-borne nutrients (in a fully-factorial design) during a period of invertebrate colonisation in the field. Effects of nutrient-rich contaminants on invertebrate recruitment were observed as changes to community composition and the abundances of taxonomic groups. Communities on no biofilm control treatments differed from those with pre-developed biofilms. Naturally developed biofilms promoted recruitment by all organisms, except barnacles, which preferred nutrient-enriched biofilms. Water-borne nutrients increased the recruitment of ascidians and barnacles, but suppressed bryozoan, serpulid polychaete and sponge recruitment. The direct and indirect impacts observed on biofilm and invertebrate communities suggest that increasing nutrient levels via nutrient-rich contaminants will result in structural community shifts that may ultimately impact ecosystem functioning within estuaries.

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.

Fast-growing oysters show reduced capacity to provide a thermal refuge to intertidal biodiversity at high temperatures.

Ecosystem engineers that modify the thermal environment experienced by associated organisms might assist in the climate change adaptation of species. This depends on the ability of ecosystem engineers to persist and continue to ameliorate thermal stress under changing climatic conditions-traits that may display significant intraspecific variation. In the physically stressful intertidal, the complex three-dimensional structure of oysters provides shading and traps moisture during aerial exposure at low tide. We assessed variation in the capacity of a faster- and slower-growing population of the Sydney Rock Oyster, Saccostrea glomerata, to persist, form three-dimensional structure and provide a cool microhabitat to invertebrates under warmer conditions. The two populations of oysters were exposed to a temperature gradient in the field by attaching them to passively warmed white, grey and black stone pavers and their growth, survivorship and colonisation by invertebrates was monitored over a 12-month period. Oysters displayed a trade-off between fast growth and thermal tolerance. The growth advantage of the fast-growing population diminished with increasing substrate temperature, and at higher temperatures, the faster-growing oysters suffered greater mortality, formed less habitat, and were consequently less effective at ameliorating low-tide air temperature extremes than slower-growing oysters. The greater survivorship of slower-growing oysters, in turn, produced a cooler microclimate which fed back to further bolster oyster survivorship. Invertebrate recruitment increased with habitat cover and was greater among the slower than the faster-growing population. Our results show that the capacity of ecosystem engineers to serve as microhabitat refugia to associated organisms in a warming climate displays marked intraspecific variation. Our study also adds to growing evidence that fast growth may come at the expense of thermal tolerance.

Influence of sedimentation in the absence of macrograzers on recruitment of an annual population of Macrocystis pyrifera in Metri Bay, Chile

AbstractThe effects of sedimentation and substrate orientation on algal and sessile invertebrate assemblages were tested on an annual population of Macrocystis pyrifera in Metri Bay, southern Chile. In the laboratory, M. pyrifera zoospores were seeded on Crepipatella fecunda shells, the primary substrate for M. pyrifera in this system. The seeded shells were deployed at Metri Bay inside cages and were orientated vertically and horizontally under two sedimentation regimes (bottom and suspended). Due to differences in grazer accessibility and the species present between the sedimentation treatments, grazers (&gt;1 cm) were excluded. We followed sporophyte development of M. pyrifera and the natural recruitment of other algal and invertebrate species. Sedimentation rates were significantly higher in the cages attached to the bottom compared to suspended cages (P &lt; 0.001). In total M. pyrifera and three additional algal genera were detected and all algal recruits showed significantly greater recruitment on the horizontally orientated substrate compared to the vertical substrate. Macrocystis pyrifera sporophytes were present only on the horizontal, suspended (less sedimentation) treatment. In contrast, Ulva and Ectocarpus spp. also occurred in the horizontal, high sediment treatment. Invertebrate recruitment (amphipods, barnacles and spirorbids) dominated the vertically oriented shells regardless of sedimentation. Results indicate that high sedimentation negatively affected the development of M. pyrifera sporophytes while other opportunistic species were able to recruit under these conditions.

Recruitment of benthic invertebrates in high Arctic fjords: Relation to temperature, depth, and season

AbstractIn the high Arctic, recruitment of hard‐bottom benthic organisms has been studied at single locations, but little is known about how it varies spatially or temporally, or how it is influenced by abiotic factors. In this study, settlement plates were simultaneously deployed at five locations in three Svalbard (Norway) fjords at depths ranging from 7 m to 215 m. Recruitment was significantly different among fjords and among locations within a fjord. Recruits at each site co‐occurred randomly even though interspecific overgrowth was observed. This finding provides further evidence that there is not necessarily a relationship between non‐random co‐occurrence and interspecific competition, such as is traditionally assumed for other isolated, island‐like habitats. We found significantly lower recruitment in an Arctic‐influenced fjord than in more Atlantic‐influenced fjords. The abundance and richness of recruits was significantly lower in fall‐winter than in spring‐summer, but the spirorbid Circeis armoricana recruited in high abundance in fall‐winter. Both the abundance and taxonomic richness of recruits declined exponentially with depth, with the hydroid Stegopoma plicatile dominating at 215 m in an Atlantic‐influenced fjord. The most abundant recruiting taxa (C. armoricana, Semibalanus balanoides, Harmeria scutulata, Celleporella hyalina) can be described as pioneer (early‐succession) species. Crustose coralline algae, a slow‐growing superior competitor, also recruited at one location. Recruitment in Svalbard is highly variable, both spatially and temporally, and our results show the influence of local factors such as adult species composition.

Tropical CO2 seeps reveal the impact of ocean acidification on coral reef invertebrate recruitment

Rising atmospheric CO2 concentrations are causing ocean acidification by reducing seawater pH and carbonate saturation levels. Laboratory studies have demonstrated that many larval and juvenile marine invertebrates are vulnerable to these changes in surface ocean chemistry, but challenges remain in predicting effects at community and ecosystem levels. We investigated the effect of ocean acidification on invertebrate recruitment at two coral reef CO2 seeps in Papua New Guinea. Invertebrate communities differed significantly between ‘reference’ (median pH7.97, 8.00), ‘high CO2’ (median pH7.77, 7.79), and ‘extreme CO2’ (median pH7.32, 7.68) conditions at each reef. There were also significant reductions in calcifying taxa, copepods and amphipods as CO2 levels increased. The observed shifts in recruitment were comparable to those previously described in the Mediterranean, revealing an ecological mechanism by which shallow coastal systems are affected by near-future levels of ocean acidification.

Inhibition of invertebrate larval settlement by biofilm ciliates

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 557:77-90 (2016) - DOI: https://doi.org/10.3354/meps11825 Inhibition of invertebrate larval settlement by biofilm ciliates Matthew G. Watson1,*, Andrew J. Scardino2, Liliana Zalizniak1, Jeff Shimeta1 1Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, Victoria, Australia 2Maritime Division, Defence Science and Technology, Fishermans Bend, Victoria, Australia *Corresponding author: matt_watson@live.com.au ABSTRACT: Protozoa, a ubiquitous component of microbial biofilms, are able to rapidly colonise new substrata and reach high abundances, yet their potential to influence invertebrate settlement on these biofilms remains largely unknown. We conducted still-water, no-choice settlement assays to determine the individual effects of 4 different species of marine biofilm-dwelling ciliates on settlement of the polychaete worm Galeolaria caespitosa. The ciliates included vagile and planktonic species common to natural assemblages. Each ciliate species significantly inhibited the settlement of G. caespitosa, with the exception of Litonotus sp. The extent of inhibition differed significantly among ciliate species. Settlement was significantly reduced in the presence of Amphisiella sp. (37.5%), Euplotes minuta (43.7%) and Uronema marinum (39.6%) over 72 h compared to the control. Settlement rates in the presence of filtrate from ciliate cultures were at no point significantly different from a control, ruling out a dissolved chemical cue; settlement was only inhibited in the physical presence of ciliates. Video analysis showed that E. minuta elicits more erratic movement and substrate avoidance in surface exploration by G. caespitosa larvae. In addition, the distribution of bacteria in the ciliate treatments was significantly more clustered than in controls, indicating a potential indirect mechanism by which ciliates impacted larval settlement. This is the first report of a behavioural response of invertebrate larvae following direct contact with ciliates, which, together with possible indirect interactions involving bacteria, may constrain invertebrate recruitment in nature. KEY WORDS: Microbial biofilms · Ciliates · Microbial ecology · Marine invertebrates · Settlement · Galeolaria caespitosa Full text in pdf format PreviousNextCite this article as: Watson MG, Scardino AJ, Zalizniak L, Shimeta J (2016) Inhibition of invertebrate larval settlement by biofilm ciliates. Mar Ecol Prog Ser 557:77-90. https://doi.org/10.3354/meps11825 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 557. Online publication date: September 28, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

The effects of substratum material and surface orientation on the developing epibenthic community on a designed artificial reef

Artificial reefs provide shelter and can be an important source of food for fish depending on the epibenthic community on the structure. The growth and diversity of this community is influenced by the substratum material and the surface orientation of the reef. Settlement plates of four materials (Perspex, sandstone, wood and steel) were deployed in three orientations (upwards, downwards and vertical) at a depth of 33 m on a designed artificial reef (DAR) off the coast of Sydney, Australia. After three months, the steel surfaces had lower invertebrate species richness, total abundance and diversity compared to other surfaces. Steel was not an ideal material for the initial recruitment and growth of epibenthic invertebrates. A longer duration would be required to develop a mature epibenthic community. Surface orientation had species-specific impacts. Surface material and orientation are important factors for developing epibenthic assemblages, and are thus likely to affect the broader artificial reef assemblage, including fish.

Native ecosystem engineer facilitates recruitment of invasive crab and native invertebrates

Native ecosystem engineers that add physical structure to ecosystems can facilitate invasive species. In this study we determined the effects of the native tube-forming serpulid worm, Galeolaria caespitose on the recruitment of the invasive New Zealand porcelain crab, Petrolisthes elongatus, and whether invasive crab recruitment was related to the recruitment of native species. P. elongatus is abundant beneath intertidal rocks around Tasmania, southern Australia, and the underside of these rocks is usually covered with a calcareous matrix formed by the serpulid. We used an experimental approach to investigate whether rocks, serpulids on the underside of rocks and adult P. elongatus influenced the recruitment P. elongatus and native communities. P. elongatus and native invertebrates only recruited in the presence of rocks indicating the importance of rock as primary recruitment habitat. Moreover, the presence of serpulids on the underside of rocks significantly increased the recruitment of P. elongatus and native invertebrates compared to rocks without serpulids. Rocks with higher densities of adult P. elongatus at the end of the experiment also had higher densities of P. elongatus recruits. The density of P. elongatus recruits did not influence native species richness and abundance although there was some evidence that high P. elongatus recruitment was correlated with shifts in native community structure. We have shown that a native ecosystem engineer facilitates recruitment of an invasive crab but this does not appear to influence the recruitment of native species.