| 1. |
- Corbera, G., et al.
(författare)
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Local-scale feedbacks influencing cold-water coral growth and subsequent reef formation
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Despite cold-water coral (CWC) reefs being considered biodiversity hotspots, very little is known about the main processes driving their morphological development. Indeed, there is a considerable knowledge gap in quantitative experimental studies that help understand the interaction between reef morphology, near-bed hydrodynamics, coral growth, and (food) particle transport processes. In the present study, we performed a 2-month long flume experiment in which living coral nubbins were placed on a reef patch to determine the effect of a unidirectional flow on the growth and physiological condition of Lophelia pertusa. Measurements revealed how the presence of coral framework increased current speed and turbulence above the frontal part of the reef patch, while conditions immediately behind it were characterised by an almost stagnant flow and reduced turbulence. Owing to the higher current speeds that likely promoted a higher food encounter rate and intake of ions involved in the calcification process, the coral nubbins located on the upstream part of the reef presented a significantly enhanced average growth and a lower expression of stress-related enzymes than the downstream ones. Yet, further experiments would be needed to fully quantify how the variations in water hydrodynamics modify particle encounter and ion intake rates by coral nubbins located in different parts of a reef, and how such discrepancies may ultimately affect coral growth. Nonetheless, the results acquired here denote that a reef influenced by a unidirectional water flow would grow into the current: a pattern of reef development that coincides with that of actual coral reefs located in similar water flow settings. Ultimately, the results of this study suggest that at the local scale coral reef morphology has a direct effect on coral growth thus, indicating that the spatial patterns of living CWC colonies in reef patches are the result of spatial self-organisation.
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| 2. |
- Allers, E., et al.
(författare)
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Resistance of Lophelia pertusa to coverage by sediment and petroleum drill cuttings
- 2013
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Ingår i: Marine Pollution Bulletin. - 0025-326X. ; 74:1, s. 132-140
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Tidskriftsartikel (refereegranskat)abstract
- In laboratory experiments, the cold-water coral Lophelia pertusa was exposed to settling particles. The effects of reef sediment, petroleum drill cuttings and a mix of both, on the development of anoxia at the coral surface were studied using O2, pH and H2S microsensors and by assessing coral polyp mortality. Due to the branching morphology of L. pertusa and the release of coral mucus, accumulation rates of settling material on coral branches were low. Microsensors detected H2S production in only a few samples, and sulfate reduction rates of natural reef sediment slurries were low (<0.3 nmol S cm−3 d−1). While the exposure to sediment clearly reduced the coral’s accessibility to oxygen, L. pertusa tolerated both partial low-oxygen and anoxic conditions without any visible detrimental short-term effect, such as tissue damage or death. However, complete burial of coral branches for >24 h in reef sediment resulted in suffocation.
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| 3. |
- Berglin, Mattias, 1970, et al.
(författare)
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The adhesion of the barnacle, Balanus improvisus, to poly(dimethylsiloxane) fouling-release coatings and poly(methyl methacrylate) panels: The effect of barnacle size on strength and failure mode
- 2001
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Ingår i: Journal of Adhesion Science and Technology. - 0169-4243. ; 15:12, s. 1485-1502
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Tidskriftsartikel (refereegranskat)abstract
- Measure men ts were made of the bond strength of cyprids and barnacles (Balanus improvisus) attached to poly(dimethylsiloxane) (PDMS) fouling-release coatings and poly(methyl methacrylate) (PMMA) panels as a function of barnacle base plate size (0.05-90 mm(2)). The vertical forces necessary to dislodge cyprids and newly metamorphosed barnacles (base plate < 0.5 mm(2)) were found to be equal for the two different substrates. This unexpected result was explained by the occurrence of cohesive failure in the cyprid/barnacle part. A significantly higher detachment force was observed for larger barnacles (base plate > 0.5 mm(2)) when dislodged from the PMMA compared to the PDMS. Analysis of the failure surfaces with light microscopy and scanning electron microscopy (SEM) showed a gradual transition in failure mode from a total cohesive within the barnacle to a mixed failure mode during barnacle growth. This transition. which is a measure of the balance between the cohesive strength of the barnacle base plate and the adhesion bond to the surface, occurs earlier or with smaller barnacles when detached from the PDMS. The quantification of the remaining fraction of the base plate at the polymeric failure surfaces appears to be a function of barnacle bioadhesive bond strength and is, therefore, suggested to be used as a new parameter for evaluating the release properties of new coatings formulations.
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| 4. |
- Berntsson, Kent M., 1963, et al.
(författare)
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Rejection of unsuitable substrata as a potential driver of aggregated settlement in the barnacle Balanus improvisus
- 2004
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 275, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- Many marine invertebrate larvae have the capacity to reject or accept settlement sites based on a broad range of cues. Species-specific settlement responses to different cues are often inferred from final settlement choice in the field. Little is known about species-specific larval behaviour in response to different cues and, in particular, how the behaviour is linked to final settlement. Rejection of unsuitable substrata may be an important driving force that leads to aggregated settlement patterns. This study examines rejection responses in relation to surface attractiveness for settlement under field and laboratory conditions in the barnacle Balanus improvisus. The attractiveness for settlement was manipulated by varying surface texture in combination with crude extract from conspecific adults. Active rejection behaviour was examined as a function of surface texture and conspecific pheromones in the field and then related to behavioural responses under static and flowing conditions in the laboratory. Recruitment was heavily reduced on substrata with ribbed microtexture compared to smooth substrata and unaffected by crude extract from conspecific adults. On average, 28% of the cyprids that encountered smooth settlement panels recruited. The proportion of cyprids recruiting on 2 microtextured substrata after encounter was 5 and 1% respectively. In behavioural experiments cyprids showed higher motion speed and dispersal rate on textured substrata, which indicated less exploratory behaviour than on smooth substrata, while an addition of conspecific extract increased intensities of surface exploration on all types of substrata. Flume experiments further demonstrated that cyprids are more prone to leave textured substrata and that the rejection rate was independent of conspecific extract. This work emphasises the role of larval behaviour as a potentially powerful mechanism determining final recruitment pattern. It is concluded that the choice of settlement site is an important factor in the settlement process of B. improvisus, and the results suggest that surface topography may be a stronger cue for settlement than chemical attraction by conspecific adults in this species. This study presents an example whereby rejection of unsuitable substrata leads to an increased larval pool on adjacent substrata that are suitable for settlement, and indicates that this process may drive aggregated settlement in the barnacle B. improvisus.
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| 5. |
- Clark, H. Poppy, et al.
(författare)
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New interactive machine learning tool for marine image analysis
- 2024
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Ingår i: ROYAL SOCIETY OPEN SCIENCE. - 2054-5703. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Advancing imaging technologies are drastically increasing the rate of marine video and image data collection. Often these datasets are not analysed to their full potential as extracting information for multiple species is incredibly time-consuming. This study demonstrates the capability of the open-source interactive machine learning tool, RootPainter, to analyse large marine image datasets quickly and accurately. The ability of RootPainter to extract the presence and surface area of the cold-water coral reef associate sponge species, Mycale lingua, was tested in two datasets: 18 346 time-lapse images and 1420 remotely operated vehicle video frames. New corrective annotation metrics integrated with RootPainter allow objective assessment of when to stop model training and reduce the need for manual model validation. Three highly accurate M. lingua models were created using RootPainter, with an average dice score of 0.94 +/- 0.06. Transfer learning aided the production of two of the models, increasing analysis efficiency from 6 to 16 times faster than manual annotation for time-lapse images. Surface area measurements were extracted from both datasets allowing future investigation of sponge behaviours and distributions. Moving forward, interactive machine learning tools and model sharing could dramatically increase image analysis speeds, collaborative research and our understanding of spatiotemporal patterns in biodiversity.
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| 6. |
- Fagerström, Vilhelm, et al.
(författare)
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Turbulence affects larval vertical swimming in the cold-water coral Lophelia pertusa
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 9:1062884
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Tidskriftsartikel (refereegranskat)abstract
- Vertical migration of marine larvae may drastically affect their dispersal, especially if they are spawned in the deep sea. Previous studies have shown that the planktonic larvae of the cold-water coral Lophelia pertusa in still water swim upwards at a speed of ca. 0.5 mm s-1 during a pre-competency period of 3–5 weeks. This behavioral trait is thought to benefit dispersion of larvae as it promotes near surface drift in relatively strong currents. In the ocean however, larvae regularly encounter turbulent water movements potentially impeding their swimming ability. With no apparent stabilizing mechanism, it may be expected that the body orientation of these larvae, and consequently their directed swimming, is sensitive to perturbation by external forces. We investigated the effects of turbulence on vertical swimming of pre-competent L. pertusa larvae by exposing them to relevant turbulence intensities within a grid-stirred tank. Larval movement and water flow were simultaneously recorded, allowing for analysis of individual larval swimming velocities. We showed that the upwards directed swimming speed generally decreased with increasing turbulence, dropping to non-significant in turbulence levels occurring near ocean boundaries. Our results do however suggest that L. pertusa larvae maintain their upwards directed swimming, albeit at reduced speed, in a major part of the water column, thus allowing them to spend part of their planktonic phase in the uppermost ocean layer. This new insight into the behavior of L. pertusa larvae in their natural environment strengthens the notion of the species as one with strong potential for long-distance dispersal. Such information is important for the understanding of L. pertusa population connectivity, and vital when developing tools for modelling of larval transport.
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| 7. |
- Georgian, Samuel E., et al.
(författare)
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Biogeographic variability in the physiological response of the cold-water coral Lophelia pertusa to ocean acidification
- 2016
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Ingår i: Marine Ecology. - : Wiley. - 0173-9565 .- 1439-0485. ; 37:6, s. 1345-1359
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Tidskriftsartikel (refereegranskat)abstract
- While ocean acidification is a global issue, the severity of ecosystem effects is likely to vary considerably at regional scales. The lack of understanding of how biogeographically separated populations will respond to acidification hampers our ability to predict the future of vital ecosystems. Cold-water corals are important drivers of biodiversity in ocean basins across the world and are considered one of the most vulnerable ecosystems to ocean acidification. We tested the short-term physiological response of the cold-water coral Lophelia pertusa to three pH treatments (pH = 7.9, 7.75 and 7.6) for Gulf of Mexico (USA) and Tisler Reef (Norway) populations, and found that reductions in seawater pH elicited contrasting responses. Gulf of Mexico corals exhibited reductions in net calcification, respiration and prey capture rates with decreasing pH. In contrast, Tisler Reef corals showed only slight reductions in net calcification rates under decreased pH conditions while significantly elevating respiration and capture rates. These differences are likely the result of environmental differences (depth, pH, food supply) between the two regions, invoking the potential for local adaptation or acclimatization to alter their response to global change. However, it is also possible that variations in the methodology used in the experiments contributed to the observed differences. Regardless, these results provide insights into the resilience of L. pertusa to ocean acidification as well as the potential influence of regional differences on the viability of species in future oceans.
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| 8. |
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| 9. |
- Hennige, S. J., et al.
(författare)
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Using the Goldilocks Principle to model coral ecosystem engineering
- 2021
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 288
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence and proliferation of reef-forming corals is of vast importance in terms of the biodiversity they support and the ecosystem services they provide. The complex three-dimensional structures engineered by corals are comprised of both live and dead coral, and the function, growth and stability of these systems will depend on the ratio of both. To model how the ratio of live: dead coral may change, the 'Goldilocks Principle' can be used, where organisms will only flourish if conditions are 'just right'. With data from particle imaging velocimetry and numerical smooth particle hydrodynamic modelling with two simple rules, we demonstrate how this principle can be applied to a model reef system, and how corals are effectively optimizing their own local flow requirements through habitat engineering. Building on advances here, these approaches can be used in conjunction with numerical modelling to investigate the growth and mortality of biodiversity supporting framework in present-day and future coral reef structures.
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| 10. |
- Johannesson, Kerstin, 1955, et al.
(författare)
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Hybrid fitness seems not to be an explanation for the partial reproductive isolation between ecotypes of Galician Littorina saxatilis
- 2000
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Ingår i: Journal of Molluscan Studies. - 0260-1230. ; 66, s. 149-156
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Tidskriftsartikel (refereegranskat)abstract
- Partial reproductive isolation between closely related groups of organisms is suggested to be of central importance during speciation. Galician populations of Littorina saxatilis are phenotypically differentiated into an upper-shore and a lower-shore morph. These mate assortatively in the mid-shore: zone of overlap, and genetic assessment shows an impeded gene flow between the parental morphs. The traditional explanation as to why assortative mating occurs is that reproductive isolation is reinforced due to hybrid unfitness. Earlier studies have, however, not found hybrids to be less viable. Likewise, growth and migratory behaviours are merely intermediate between those of the parental morphs. In the present study we compared male and female fertility components of the parental morphs and the hybrids to test hypotheses of decreased hybrid fertility. The results showed that hybrid males were as fertile as other males, and hybrid females did not produce fewer embryos, nor aborted embryos at a higher rate, than the parental morphs.
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