This dataset contains the digitized treatments in Plazi based on the original journal article Yap, Nicholas Wei Liang, Tan, Ria, Yong, Clara Lei Xin, Tan, Koh Siang, Huang, Danwei (2019): Sea anemones (Cnidaria, Actiniaria) of Singapore: redescription and taxonomy of Phymanthuspinnulatus Martens in Klunzinger, 1877. ZooKeys 840: 1-20, DOI: http://dx.doi.org/10.3897/zookeys.840.31390, URL: http://dx.doi.org/10.3897/zookeys.840.31390
There is a growing interest in transplanting corals onto the intertidal section of artificial coastal defences (e.g., seawalls) as an ecological engineering strategy to enhance biodiversity on urban shores. However, this inevitably results in exposure to the harsh environmental conditions associated with emersion (aerial exposure). Although the effects of a multitude of environmental stressors on corals have been examined, their photophysiological and gene expression responses to emersion stress remain understudied, as does the among-genotype variation in these responses. In this study, we conducted an in situ experiment to test the effects of increased daily emersion duration on a locally common intertidal coral, Dipsastraea cf. lizardensis. Coral fragments (n = 3) from five genotypically distinct colonies were subjected to two treatments: (1) increased daily emersion duration (~4.5 h d−1) and, (2) control (~3 h d−1) for three consecutive days during spring low tide. We examined the post-experimental photophysiological responses and expression level of a stress-associated gene, Hsp16. Relative to the controls, coral fragments that were exposed to longer daily emersion duration displayed significantly reduced effective quantum yield, while endosymbiont density varied significantly among genotypes across the experimental conditions. We found no significant differences in chlorophyll a concentration and Hsp16 gene expression level, suggesting that changes in these processes may be gradual and the duration of treatment that the corals were subjected to is likely within their tolerance limits. Taken together, it appears that D. cf. lizardensis displays substantial capacity to cope with sup-optimal conditions associated with emersion which makes it a promising candidate for transplantation onto intertidal seawalls. However, within-species variation in their stress response indicates that not all genotypes respond similarly to emersion, and this should be taken into account when selecting donor colonies for transplantation.
Marine microplastics have become a pernicious global pollution issue. As field surveys to determine microplastic abundance in the marine environment and/or biota become more common, it is important to refine collection techniques to minimize contamination of samples. However, most contemporary sampling equipment is fabricated with plastic components. Microplastic contamination during sample collection can be minimized from the onset by employing techniques that are plastic-less or with minimal plastic-to-sample contact. Here we describe plastic-less equipment and techniques for field sampling of water, sediment, and organisms. Some of these are traditional designs that pre-date the plastic era and can be revived or repurposed for microplastic sampling. Others are self-developed and fabricated using materials such as metal, wood, silk, and cork. For relatively small costs in time and funds, it is possible to greatly reduce, or eliminate, plastics from the field sampling process.
Context In contrast to marine environments, microplastic pollution in freshwater systems is understudied. Previous research suggests that freshwater macrophytes function as microplastic sinks, which, because they are at the base of food webs, has implications for higher trophic levels. Aim This study compares the ability of freshwater plants with different leaf morphologies to trap downwelling microplastics. Method Microplastics (800–1000 μm polyamide grains) were deposited onto three macrophyte species, namely, Cabomba caroliniana, Egeria densa, and Hygrophila polysperma. Microplastic mass retained was calculated as the percentage of microplastic mass captured by the plant and standardised microplastic retention was calculated as the absolute microplastic mass retained (g) divided by plant dry mass (g). Results The amount of trapped microplastics differed significantly among species, with the highest amount trapped by C. caroliniana (39.3%; 7.91 g g−1), followed by E. densa (28.8%; 5.30 g g−1) and H. polysperma (17.6%; 4.47 g g−1). Conclusion Significant differences in microplastic retention among species may be attributed to variation in leaf morphology. Implications These findings have potential applications in bioremediation and biomonitoring, where freshwater macrophytes could help with the tracking and mitigation of microplastics in the environment.
Seagrass beds can trap large amounts of marine debris leading to areas of accumulation, known as 'sinks', of anthropogenic particles. While the presence of vegetation can enhance accumulation, less is known about how the trapping effect changes from vegetated to non-vegetated patches. To test this, vegetation and sediment were sampled along a gradient from the centre of seagrass beds to nearby unvegetated patches. To determine whether trapped particles can lead to increased accumulation in associated fauna, gastropods were also collected across the seagrass gradient. Extracted anthropogenic particles were counted and characterised. Particles were detected in all sample types and reached quantifiable limits in at least 50% of sediment and gastropod samples. There were no significant differences found in the distribution of particles found in seagrass beds compared to unvegetated patches. Thus, multiple factors likely contribute to the trapping efficiency of biogenic habitats besides simply the presence or absence of vegetation.
Abstract Our understanding of how sea anemones reproduce in the equatorial Central Indo‐Pacific region remains poor compared to other marine regions. Here we report the gametogenic cycles of Phymanthus pinnulatus , a zooxanthellate sea anemone found throughout the Indo‐Pacific tropics. Observations were based on 41 individuals collected in Singapore. We found P. pinnulatus to be gonochoric, with an equal sex ratio of 1:1. Phases of oogenesis and spermatogenesis were detailed for the first time in P. pinnulatus, and were consistent with phases in other actiniarians. Females with pedal disc diameters <10 mm were found to asynchronously produce oocytes. We also found that trophonemata were associated with both oocytes and spermaries during gametogenesis. In Singapore, the periods during which gametes matured in each sex of P. pinnulatus appeared to overlap. We were unable distinguish whether spawning was annual or continuous in P. pinnulatus . Our observations on the occurrence of maturing and matured gametes in P. pinnulatus were similar to those reported for other species within the Central Indo‐Pacific. It also coincided with the multispecies spawning of scleractinian corals in Singapore. This study contributes to the growing body of work focused on the biology of tropical actiniarians in the Central Indo‐Pacific region.
In response to the environmental damage caused by urbanization, Nature-based Solutions (NbS) are being implemented to enhance biodiversity and ecosystem processes with mutual benefits for society and nature. Although the field of NbS is flourishing, experiments in different geographic locations and environmental contexts have produced variable results, with knowledge particularly lacking for the subtidal zone. This study tested the effects of physical complexity on colonizing communities in subtidal habitats in two urban locations: (1) Plymouth, United Kingdom (northeast Atlantic) and (2) Tel Aviv, Israel (eastern Mediterranean) for 15- and 12-months, respectively. At each location, physical complexity was manipulated using experimental tiles that were either flat or had 2.5 or 5.0 cm ridges. In Plymouth, biological complexity was also manipulated through seeding tiles with habitat-forming mussels. The effects of the manipulations on taxon and functional richness, and community composition were assessed at both locations, and in Plymouth the survival and size of seeded mussels and abundance and size of recruited mussels were also assessed. Effects of physical complexity differed between locations. Physical complexity did not influence richness or community composition in Plymouth, while in Tel Aviv, there were effects of complexity on community composition. In Plymouth, effects of biological complexity were found with mussel seeding reducing taxon richness, supporting larger recruited mussels, and influencing community composition. Our results suggest that outcomes of NbS experiments are context-dependent and highlight the risk of extrapolating the findings outside of the context in which they were tested.
Despite the ubiquity of sea anemones (Cnidaria: Actiniaria) in tropical ecosystems, our understanding of their biodiversity and taxonomy is limited. Here we re-establish the identity of an intertidal zooxanthellate species, Phymanthuspinnulatus Martens in Klunzinger, 1877. Originally described from a single preserved specimen in the Berlin Museum by CB Klunzinger, his brief footnote lacked crucial details to positively identify the species. Our redescription is based on more than 50 living individuals of P.pinnulatus collected from its type locality, Singapore. These were examined and compared with type materials of the species and its congeners. Specimens of P.pinnulatus differ from syntypes of species described as Phymanthuslevis Kwietniewski, 1898 from Indonesia, as well as Phymanthussansibaricus Carlgren, 1900 and Phymanthusstrandesi Carlgren, 1900, both described from East Africa. Phymanthuspinnulatus was encountered on the lower intertidal, among coral rubble and between rocky crevices. It is vibrantly coloured and has 96 marginal tentacles with branching outgrowths along each, resulting in a ‘frilly’ appearance. The anemone has a flat expanded oral disc, with discal tentacles that are inconspicuous and reduced, unlike syntypes of its congeners. Details of its live appearance, musculature, and cnidom are also provided for the first time. Overall, types of cnidae and capsule sizes differ from other known species of Phymanthus documented elsewhere. It is inferred that P.pinnulatus has a wide distribution that extends eastwards from Singapore, as far as Ambon and the Torres Straits. Some individuals reported as Phymanthusmuscosus Haddon and Shackleton, 1893 and Phymanthusbuitendijki Pax, 1924 are probably P.pinnulatus . This morphological analysis provides new insights into the characters used to delimit P.pinnulatus , clarifies its geographical distribution, and contributes to an ongoing revision of the genus Phymanthus .
Southeast Asia is considered to have some of the highest levels of marine plastic pollution in the world. It is therefore vitally important to increase our understanding of the impacts and risks of plastic pollution to marine ecosystems and the essential services they provide to support the development of mitigation measures in the region. An interdisciplinary, international network of experts (Australia, Indonesia, Ireland, Malaysia, the Philippines, Singapore, Thailand, the United Kingdom, and Vietnam) set a research agenda for marine plastic pollution in the region, synthesizing current knowledge and highlighting areas for further research in Southeast Asia. Using an inductive method, 21 research questions emerged under five non-predefined key themes, grouping them according to which: (1) characterise marine plastic pollution in Southeast Asia; (2) explore its movement and fate across the region; (3) describe the biological and chemical modifications marine plastic pollution undergoes; (4) detail its environmental, social, and economic impacts; and, finally, (5) target regional policies and possible solutions. Questions relating to these research priority areas highlight the importance of better understanding the fate of marine plastic pollution, its degradation, and the impacts and risks it can generate across communities and different ecosystem services. Knowledge of these aspects will help support actions which currently suffer from transboundary problems, lack of responsibility, and inaction to tackle the issue from its point source in the region. Being profoundly affected by marine plastic pollution, Southeast Asian countries provide an opportunity to test the effectiveness of innovative and socially inclusive changes in marine plastic governance, as well as both high and low-tech solutions, which can offer insights and actionable models to the rest of the world.
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