Journal Articles - UP - MSI
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- Influence of tidal location on morphology, photosynthesis and pigments of the agarophyte, Gelidiella acerosa, from Northern PhilippinesGanzon-Fortes, E. T. (Springer, 1997-12)The red seaweed agarophyte, Gelidiella acerosa (Forsskål) (Feldmann& Hamel) was collected from tidepools, high intertidal rocks, and shallow subtidal areas along a reef flat in Ilocos Norte, northern Philippines. The three populations were compared during the summer (dry) and rainy (wet) seasons to determine changes in morphology and photoacclimation capacity as possible use in mariculture. During summer months (February to April) after exposure to environmental extremes (i.e. the highest percent of minus tides during daylight, high light regimes, desiccation, and solar bleaching), the populations differed in their morphologies and responses to increasing irradiance levels (P–I curve). Tidepool plants were the tallest, bushiest, and with increased diameter of cortical cells; while, high intertidal plants were the shortest, with sparse branching pattern and decreased diameter of cortical cells. Although their saturation irradiances indicated shade tolerance (Ik = 52 − 112 µmol photon m -2 s-1). Their differential light saturation curves (P-I curves) suggested a capacity to acclimate to ambient light regimes. For example, plants from the high intertidal zone showed higher photosynthetic rates and saturation irradiances, slightly lower initial slopes of the P-I curves and levels of light harvesting accessory pigments, rphycoerhythrin (R-PE) and rphycocyanin (R-PC), after being exposed to higher light regimes. In contrast, plants from tidepools and shallow subtidal areas had lower photosynthetic rates and saturation irradiances, slightly steeper initial slopes of the P-I curves and levels of R-PE and R-PC, having been exposed to lower light regimes. During the rainy months (June to November) no significant responses in these parameters were recorded. Comparison of the P-I responses of vegetative and tetrasporic plants showed these to vary with season. The data suggest that when plants became reproductive their physiological fitness either was unchanged or slightly enhanced. These results indicate that all three populations of G. acerosa could be used as seed stock for mariculture.
- Contrasting recolonization strategies in multi-species seagrass meadowsRollon, Rene N.; Van Steveninck, Erik D.De Ruyter; Van Vierssen, Wim; Fortes, Miguel D. (Elsevier BV, 1999-12)This study shows that in a multi-species seagrass meadow in a shallow and clear-water site, all the former seagrass species were able to recolonize in the artificially created gaps of 0.25 m2 in size within ca. 2 yr. Extrapolation of the recolonization curves of the different species predicted a full recovery within 10 yr post-disturbance. Fitted curves for the dominant species Enhalus acoroides and Thalassia hemprichii showed contrasting strategies, the latter having a comparatively high intrinsic rate, achieving full recovery within ca. 2 yr post-disturbance. E. acoroides was the latest species to establish and the projected full-recovery time was among the longest (ca. 10 yr). The effect of timing of gap creation was generally not significant (except for Syringodium isoetifolium) neither was the temporal variation in density of most species outside the gaps. As recolonization by sexual propagules was found to be low, increasing the gap size would most probably require a much longer recovery period. A crude estimate for E. acoroides would be >10 yr for 1 m2 of gap. Further, since the densities of most seagrass species vary significantly between sites, and colonization rates depend on adjacent seagrass densities, the recovery curves would also be different across sites.
- Physiological and ecological aspects of coral transplantationYap, H. T.; Alvarez, R. M.; Custodio, H. M.; Dizon, R. M. (Elsevier BV, 1998-10)The growth and mortality of transplants of two species of scleractinian corals, Porites cylindrica Dana and P. rus Forskal (1775), were monitored over 16 months in a reef in the northwestern Philippines. Transplants were in two sizes (nubbin, ∼8 cm in length; and fist-sized, ∼8 cm in diameter) and deployed at two depths (1 and 10 m). Specimens at the shallow depth had more rapid growth than the deeper ones. Light had significant effects on coral growth while temperature, salinity, water motion and sedimentation did not. Smaller corals consistently registered greater percentage increases in size as compared to the larger ones. Small transplants of P. cylindrica showed higher percentage growth rates than those of P. rus. Contrary to expectations, there were no differences in transplant mortality due to size. Over the course of the experiment, mortality was generally confined to the shallow depth. It was brought about either by algal competition or by strong water movement.
- Root production and belowground seagrass biomassDuarte, C. M.; Merino, M.; Agawin, N.; Uri, J.; Fortes, M. D.; Gallegos, M. E.; Marbá, N.; Hemminga, M. A. (Inter-Research Science Center, 1998)The root and rhizome biomass of the seagrass species present in 3 mixed and 2 monospecific meadows representative of different floras (Spanish Mediterranean, Mexican Caribbean, Kenyan coast, and the South China Sea off The Philippines) was examined to test for the existence of general patterns in the distribution of their biomass in the sediments, and to test a simple approach based on age determinations to estimate root production. The thickness of the roots was scaled to the thickness of the seagrass rhizomes (r = 0.92, p < 0.001). Root and rhizome biomass were high (>100 and >200 g DW m-2, respectively) for the mixed meadows examined; these belowground structures had a projected surface area often exceeding 1m2 m-2 when roots and rhizomes were considered together, and they formed a dense web of root material comprising several hundred meters per square meter. Belowground biomass showed considerable vertical stratification within the sediments, with a tendency for the larger species to extend deeper into the sediments than smaller ones. This tendency for segregation should reduce the potential interspecific competition for sediment resources, which is likely to be greater in the uppermost layers, where the belowground biomass is more evenly distributed among species. The rate of adventitious root production on vertical shoots varied from species that produced a root on almost every node to species that produced 1 adventitious root for every 10 nodes. Root production--both on horizontal rhizomes and vertical shoots--was substantial, with the combined root production approaching, or exceeding, 1000 g DW m-2 yr-1. The resulting root turnover was quite high, with most values ranging between 2 and 10 yr-1, indicative of a characteristic turnover time of months for the root compartment. The estimates of root production derived here often exceed those of rhizome production and reach values comparable to leaf production, clearly demonstrating that root production is an important component (up to 50%) of total seagrass production.
- Damage and recovery of four Philippine corals from short-term sediment burialWesseling, I.; Uychiaoco, A. J.; Aliño, P. M.; Aurin, T.; Vermaat, J. (Inter-Research Science Center, 1999)Recovery of corals after full burial with littoral sediment (16% silt, 46% fine sand and 38% coarse sand; 28% CaCO3) was monitored in 2 field experiments at the reefs off Lucero, Bolinao (Pangasinan, NW Philippines), from April to May 1996. In the first experiment at 2 m depth, Porites was buried for 0, 6, 20 and 68 h; a second experiment was done at 5 m depth and 4 common taxa (Porites, Galaxea, Heliopora and Acropora) were buried for 20 h. At 2 m depth, Porites was not affected by 6 h burial compared to the controls that were not buried. Increasing burial time had increasingly more serious effects. Burial for 20 h resulted in increased discoloration of the coral tissue. After 68 h of burial, up to 90% of the tissue bleached in the first days. About 50% of this tissue disappeared subsequently and bare coral skeleton became exposed or were covered with algae. After a few weeks, however, recovery took place: the bare areas were recolonized from surrounding surviving tissue or from highly retracted polyps in the affected area. In the corals that had been buried for 20 h no more significant differences from the controls were observed after 3 wk. For those that were buried for 68h, this was the case after 4 wk. At 5 m depth, all Acropora died after the 20 h burial treatment, but the other taxa recovered in a comparable way to the Porites in the first experiment at 2 m depth. It is concluded that complete burial will cause considerable whole-colony mortality in at least Acropora, and thus may result in a permanent loss of coral taxa from reefs that are subject to such intense sedimentation events. Less sensitive taxa incur substantial damage but significant recovery was observed after a month.
- Molecular phylogeny of three unarmored dinoflagellates from Masinloc Bay, Zambales, Central Luzon, with a description of the morphology of Gymnodinium catenatum H.W.GrahamBenico, Garry; Azanza, Rhodora (Science and Technology Information Institute, 2021-10-27)Unambiguous identification of unarmored dinoflagellates is important in distinguishing toxic from non-toxic species occurring in the coastal waters of the Philippines. In this study, molecular phylogeny inferred from rDNA sequences of Gymnodinium catenatum, Gymnodinium impudicum, and Akashiwo sanguinea-collected from Masinloc Bay, Zambales, Central Luzon-is reported for the first time. Morphology of G. catenatum was critically examined using light and confocal laser scanning microscopy. The three unarmored dinoflagellates were identified as G. catenatum, G. impudicum, and A. sanguinea based on their phylogenetic positions inferred from LSU and SSU rDNA. Both G. catenatum and G. impudicum grouped in a well-supported clade of Gymnodinium sensu stricto, which includes other genera of unarmored dinoflagellates, confirming the polyphyly of the clade. Akashiwo sanguinea separated into four subclades, which is similar to previous reports-with our strain grouping with sequences from Malaysia, Singapore, and China. Cellular characteristics of our G. catenatum are congruent with earlier reports particularly its long chain-forming habit (up to 64 cells) and large cell size (44.6-63.3 µm long). Our result is the first verified record of G. impudicum and A. sanguinea in the Philippines, and the first record of G. catenatum as another highly toxic dinoflagellate species occurring in Masinloc Bay.
- Low coral bleaching prevalence at the Bolinao-Anda Reef Complex, northwestern Philippines during the 2016 thermal stress eventQuimpo, Timothy Joseph R.; Requilme, Jeremiah Noelle C.; Gomez, Elizabeth J.; Sayco, Sherry Lyn G.; Tolentino, Mark Paulo S.; Cabaitan, Patrick C. (Elsevier BV, 2020-11)Here, we examined the coral bleaching responses during the 2016 thermal stress event and post-bleaching changes in coral communities in the heavily disturbed reefs of the Bolinao-Anda Reef Complex (BARC), northwestern Philippines. Less than 25% of colonies bleached, with 77% attributed to five genera (Dipsastrea, Porites, Fungia, Seriatopora, and Montipora). Coral bleaching prevalence was associated with site location, coral composition, and coral abundance, suggesting that small-scale variation (<20 km) in coral communities (taxa and density) influences spatial variation in coral bleaching prevalence. There was no noticeable change in coral composition and cover two years after the bleaching event as exposure to chronic disturbance likely selected for the dominance of stress tolerant coral taxa and communities. Results show that the 2016 thermal stress event caused coral bleaching but with low prevalence at the BARC, which suggests that disturbed reefs may provide spatial refuge to coral communities from thermal stress.We acknowledge M Ponce, F Castrence, R de Guzman, G de Guzman, R Adolfo, and R Uriarte for the field assistance; and boatmen and administration from the Bolinao Marine Laboratory of the UPMSI (University of the Philippines Marine Science Institute) for their valuable assistance in the logistics and field works. We are grateful to R Dizon for kindly reading and providing suggestions that improved the manuscript. This study was funded by the OVCRD (Office of the Vice Chancellor for Research and Development) Outright Research Grant (Project No. 161607 PNSE) and the Marine Science Institue In-house Research Grant of the University of the Philippines; and grants from the Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development of the Department of Science and Technology (QMSR-MRRD-MEC-295-1449 and QMSR-MRRD-MEC314-1542) of PC Cabaitan.
- Biochemical mapping of Pyrodinium bahamense unveils molecular underpinnings behind organismal processesSubong, Bryan John J.; Malto, Zabrina Bernice L.; Lluisma, Arturo O.; Azanza, Rhodora V.; Salvador-Reyes, Lilibeth A. (MDPI, 2021-12-11)Proteins, lipids, and carbohydrates from the harmful algal bloom (HAB)-causing organism Pyrodinium bahamense were characterized to obtain insights into the biochemical processes in this environmentally relevant dinoflagellate. Shotgun proteomics using label-free quantitation followed by proteome mapping using the P. bahamense transcriptome and translated protein databases of Marinovum algicola, Alexandrium sp., Cylindrospermopsis raciborskii, and Symbiodinium kawagutii for annotation enabled the characterization of the proteins in P. bahamense. The highest number of annotated hits were obtained from M. algicola and highlighted the contribution of microorganisms associated with P. bahamense. Proteins involved in dimethylsulfoniopropionate (DMSP) degradation such as propionyl CoA synthethase and acryloyl-CoA reductase were identified, suggesting the DMSP cleavage pathway as the preferred route in this dinoflagellate. Most of the annotated proteins were involved in amino acid biosynthesis and carbohydrate degradation and metabolism, indicating the active roles of these molecules in the vegetative stage of P. bahamense. This characterization provides baseline information on the cellular machinery and the molecular basis of the ecophysiology of P. bahamense.
- Characterization of the hidden break in giant clam 28S ribosomal RNATan, Keana; Conaco, Cecilia (Oxford University Press, 2021-09)The molluscan 28S ribosomal RNA (rRNA) naturally cleaves into two fragments of similar size as 18S rRNA. This phenomenon, known as the hidden break, has been described in many other protostome species. Here, we characterize the 28S rRNA hidden break region in seven giant clam species, Tridacna gigas, T. derasa, T. maxima, T. noae, T. crocea, Hippopus hippopus and H. porcellanus. We confirm that the break consistently occurs in giant clams and is observed in all tissues and developmental stages. The region of the giant clam 28S rRNA break is located at a position homologous to the well-characterized 28S rRNA break in insects. High AU content and a stem–loop secondary structure in the region may contribute to fragmentation of the 28S rRNA molecule. An awareness of the existence of the hidden break in molluscs, such as the giant clams, which are emerging systems for understanding how environmental change affects life in the ocean, will facilitate progress of RNA sequencing-based analyses that currently rely on standard RNA profiles as a measure of sample integrity.The authors would like to thank Dr Ronnie Estrellada of the Semirara Marine Laboratory and Hatchery for generously providing giant clam samples, the Bolinao Marine Laboratory for providing access to the Silaqui Island Giant Clam Ocean Nursery and Niño Dan Posadas for sharing sponge RNA. This work was supported by a grant to C.C. from the Philippine Council for Agriculture, Aquaculture and Natural Resources Research and Development of the Department of Science and Technology (grant no. QMSR-MRRD-MEC-314-1545).
- Evolutionary trends in large pelagic filter-feedersStiefel, Klaus M. (Informa UK Limited, 2020-01-16)This paper attempts a synthesis of the evolution of large pelagic filter-feeding animals from the Cambrian to the present. Lineages known or suspected to have evolved large pelagic filter-feeding species are, in the order of their appearance, stem euarthropods, agnathan fishes, nautiloid cephalopods, placoderms, sharks, bony fishes, reptiles, ammonite cephalopods, and mammals. I discuss evolutionary trends which are apparent from the evolution of the large pelagic filter-feeding niche, which are 1. a size increase relative to their ancestral species, 2. the transition between taxonomic groups giving rise to pelagic filter-feeders, with vertebrates dominating the post-Cambrian, 3. the evolution of large pelagic filter-feeders from large carnivores in most, but not all cases, and 4. lengthy gaps in the record of pelagic filter-feeders around four of the big five mass extinctions.