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Ocean urea fertilization for carbon credits poses high ecological risks
Glibert, Patricia M.; Azanza, Rhodora; Burford, Michele; Furuya, Ken; Abal, Eva; Al-Azri, Adnan; Al-Yamani, Faiza; Andersen, Per; Anderson, Donald M.; Beardall, John; Berg, G. Mine; Brand, Larry; Bronk, Deborah; Brookes, Justin; Burkholder, JoAnn M.; Cembella, Allan; Cochlan, William P.; Collier, Jackie L.; Collos, Yves; Diaz, Robert; Doblin, Martina; Drennen, Thomas; Dyhrman, Sonya; Fukuyo, Yasuwo; Furnas, Miles; Galloway, James; Granéli, Edna; Ha, Dao Viet; Hallegraeff, Gustaaf; Harrison, John; Harrison, Paul J.; Heil, Cynthia A.; Heimann, Kirsten; Howarth, Robert; Jauzein, Cécile; Kana, Austin A.; Kana, Todd M.; Kim, Hakgyoon; Kudela, Raphael; Legrand, Catherine; Mallin, Michael; Mulholland, Margaret; Murray, Shauna; O'Neil, Judith; Pitcher, Grant; Qi, Yuzao; Rabalais, Nancy; Raine, Robin; Seitzinger, Sybil; Salomon, Paulo S.; Solomon, Caroline; Stoecker, Diane K.; Usup, Gires; Wilson, Joanne; Yin, Kedong; Zhou, Mingjiang; Zhu, Mingyuan (Elsevier, 2008)
The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.
Effects of environmental regulations on heavy metal pollution decline in core sediments from Manila Bay
Hosono, Takahiro; Su, Chih-Chieh; Siringan, Fernando; Amano, Atsuko; Onodera, Shin-ichi (Elsevier, 2010)
We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with 210Pb dating to find out the effects of environmental regulations after the 1990s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 1990s due to stricter environmental regulations, Administrative Order No. 42, being enforced by the Philippines government. The presented data and methodology should form the basis for future monitoring, leading to pollution control, and to the generation of preventive measures at the pollution source for the maintenance of environmental quality in the coastal metropolitan city of Manila. Although this is the first report of a reduction in pollution in Asian developing country, our results suggest that we can expect to find similar signs of pollution decline in other parts of the world as well.
17-year change in species composition of mixed seagrass beds around Santiago Island, Bolinao, the northwestern Philippines
Tanaka, Yoshiyuki; Go, Gay Amabelle; Watanabe, Atsushi; Miyajima, Toshihiro; Nakaoka, Masahiro; Uy, Wilfredo H.; Nadaoka, Kazuo; Watanabe, Shuichi; Fortes, Miguel D. (Elsevier, 2014)
Effects of fish culture can alter the adjacent ecosystems. This study compared seagrass species compositions in 2012 with those in 1995, when fish culture was less intensive compared to 2012 in the region. Observations were conducted at the same four sites around Santiago Island, Bolinao: (1) Silaqui Island, (2) Binaballian Loob, (3) Pislatan and (4) Santa Barbara, and by using the same methods as those of Bach et al. (1998). These sites were originally selected along a siltation gradient, ranging from Site 1, the most pristine, to Site 4, a heavily silted site. By 2012, fish culture had expanded around Sites 2, 3 and 4, where chlorophyll a (Chl a) was greater in 2012 than in 1995 by one order of magnitude. Enhalus acoroides and Cymodocea serrulata, which were recorded in 1995, were no longer present at Site 4, where both siltation and nutrient load are heavy.
Variation in macrofaunal communities of sea grass beds along a pollution gradient in Bolinao, northwestern Philippines
Leopardas, Venus; Honda, Kentaro; Go, Gay Amabelle; Bolisay, Klenthon; Pantallano, Allyn Duvin; Uy, Wilfredo; Fortes, Miguel; Nakaoka, Masahiro (Elsevier, 2016)
This study examined the variation of macrofaunal communities in sea grass beds along a pollution gradient in Bolinao, northwestern Philippines. We established four stations and compared the diversity and abundance of macrofauna between them. The Shannon diversity index in the least polluted station was more than twice higher than that in the most polluted one. Abundance was more than thrice higher in the most polluted station. The species composition generally varied, with community difference explained largely by the predominance of the filter-feeding bivalve Gafrarium pectinatum and polychaete Capitella capitata. Species heterogeneity was reduced along the pollution gradient by approximately 19% from the least polluted to the most polluted station. This reduction indicates biodiversity alteration, which has a significant impact on ecosystem functioning. Aspects of species heterogeneity should be considered in environmental impact assessments and the management of coastal areas encountered with anthropogenic disturbances.
Phosphorus as a driver of nitrogen limitation and sustained eutrophic conditions in Bolinao and Anda, Philippines, a mariculture-impacted tropical coastal area
Ferrera, Charissa M.; Watanabe, Atsushi; Miyajima, Toshihiro; San Diego-McGlone, Maria Lourdes; Morimoto, Naoko; Umezawa, Yu; Herrera, Eugene; Tsuchiya, Takumi; Yoshikai, Masaya; Nadaoka, Kazuo (Elsevier, 2016)
The dynamics of nitrogen (N) and phosphorus (P) was studied in mariculture areas around Bolinao and Anda, Philippines to examine its possible link to recurring algal blooms, hypoxia and fish kills. They occur despite regulation on number of fish farm structures in Bolinao to improve water quality after 2002, following a massive fish kill in the area. Based on spatiotemporal surveys, coastal waters remained eutrophic a decade after imposing regulation, primarily due to decomposition of uneaten and undigested feeds, and fish excretions. Relative to Redfield ratio (16), these materials are enriched in P, resulting in low N/P ratios (~ 6.6) of regenerated nutrients. Dissolved inorganic P (DIP) in the water reached 4 μM during the dry season, likely exacerbated by increase in fish farm structures in Anda. DIP enrichment created an N-limited condition that is highly susceptible to sporadic algal blooms whenever N is supplied from freshwater during the wet season.
Accumulation and exposure classifications of plastics in the different coastal habitats in the western Philippine archipelago
Gomez, Norchel Corcia F.; Cragg, Simon M.; Ghiglione, Jean-François; Onda, Deo Florence L. (Elsevier BV, 2023-11)
Studies consistently ranked the Philippines as one of the top contributors of plastic wastes leaking into the ocean. However, most of these were based on probabilities and estimates due to lack of comprehensive ground-truth data, resulting also in the limited understanding of the contributing factors and drivers of local pollution. This makes it challenging to develop science-driven and locally-contextualized policies and interventions to mitigate the problem. Here, 56 sites from different coastal habitats in the western Philippine archipelago were surveyed for macroplastics standing stock, representing geographic regions with varying demography and economic activities. Clustering of sites revealed three potential influencing factors to plastic accumulation: population density, wind and oceanic transport, and habitat type. Notably, the amount and types of dominant plastics per geographic region varied significantly. Single-use plastics (food packaging and sachets) were the most abundant in sites adjacent to densely populated and highly urbanized areas (Manila Bay and eastern Palawan), while fishing-related materials dominated in less populated and fishing-dominated communities (western Palawan and Bolinao), suggesting the local industries significantly contributing to the mismanaged plastics in the surveyed sites. Meanwhile, isolated areas such as islands were characterized by the abundance of buoyant materials (drinking bottles and hygiene product containers), emphasizing the role of oceanic transport and strong connectivity in the oceans. Exposure assessment also identified single-use and fishing-related plastics to be of “high exposure (Type 4)” due to their high abundance and high occurrence. These increase their chances of encountering and interacting with organisms and habitats, thus, resulting into more potential harm. This study is the first comprehensive work done in western Philippines, and results will help contextualize local pollution, facilitating more effective management and policymaking.
Genome analysis reveals three distinct lineages of the cosmopolitan white shark
Wagner, Isabel; Smolina, Irina; Koop, Martina E.L.; Bal, Thijs; Lizano, Apollo M.; Choo, Le Qin; Hofreiter, Michael; Gennari, Enrico; de Sabata, Eleonora; Shivji, Mahmood S.; Noble, Leslie R.; Jones, Catherine S.; Hoarau, Galice (Cell Press, 2024)
The white shark (Carcharodon carcharias) (Linnaeus, 1758), an iconic apex predator occurring in all oceans, is classified as Vulnerable globally—with global abundance having dropped to 63% of 1970s estimates,—and as Critically Endangered in Europe. Identification of evolutionary significant units and their management are crucial for conservation, especially as the white shark is facing various but often region-specific anthropogenic threats. Assessing connectivity in a cosmopolitan marine species requires worldwide sampling and high-resolution genetic markers. Both are lacking for the white shark, with studies to date typified by numerous but geographically limited sampling, and analyses relying largely on relatively small numbers of nuclear microsatellites, which can be plagued by various genotyping artefacts and thus require cautious interpretation. Sequencing and computational advances are finally allowing genomes to be leveraged into population studies, with datasets comprising thousands of single-nucleotide polymorphisms (SNPs). Here, combining target gene capture (TGC) sequencing (89 individuals, 4,000 SNPs) and whole-genome re-sequencing (17 individuals, 391,000 SNPs) with worldwide sampling across most of the distributional range, we identify three genetically distinct allopatric lineages (North Atlantic, Indo-Pacific, and North Pacific). These diverged 100,000–200,000 years ago during the Penultimate Glaciation, when low sea levels, different ocean currents, and water temperatures produced significant biogeographic barriers. Our results show that without high-resolution genomic analyses of samples representative of a species’ range, the true extent of diversity, presence of past and contemporary barriers to gene flow, subsequent speciation, and local evolutionary events will remain enigmatic.
Institutional dimensions of coral reef restoration in the Philippines
Matorres, Dane Erlo; Fabinyi, Michael; Horigue, Vera; Novilla, Carmela Therese; Baria-Rodriguez, Maria Vanessa (Elsevier Ltd, 2024)
While the Philippines is mostly known for its experiences on marine protected areas, local governments and non-government organizations are increasingly using coral restoration with the aim of rehabilitating degraded reef areas. Since the establishment of artificial reefs in the 1970s, the application, techniques and corresponding policy directives for reef restoration have evolved over time, and restoration has recently generated significant interest and investments from donors and government agencies. As the Philippines does not have a policy framework to support effective and sustainable practices for the use of different coral restoration techniques, the increase and unregulated use of restoration may result in unintended consequences and pose potential challenges to coastal management. To address this gap, we conducted a review of existing coral restoration policies, programs and projects across the country, with a focus on social, economic and governance aspects. The study collated existing published literature and unpublished information on coral restoration in the country, and conducted key informant interviews. The results show that coral restoration continues to increase, and that existing guidelines on coral restoration are poorly implemented and not widely understood among practitioners. While coral restoration projects reported ecological benefits, socio-economic impacts are limited. The evidence supports the need to review existing policies and contextualize coral restoration to contribute to relevant policy decisions about the restoration and protection of reefs. © 2024 The Authors
Pseudocryptic diversity and species boundaries in the sea cucumber Stichopus cf. horrens (Echinodermata: Stichopodidae) revealed by mitochondrial and microsatellite markers
Lizano, Apollo Marco D.; Kim, Kenneth M.; Juinio-Meñez, Marie Antonette; Ravago-Gotanco, Rachel (Nature Research, 2024)
Morphologically cryptic and pseudo-cryptic species pose a challenge to taxonomic identification and assessments of species diversity and distributions. Such is the case for the sea cucumber Stichopus horrens, commonly confused with Stichopus monotuberculatus. Here, we used mitochondrial cytochrome oxidase subunit I (COI) and microsatellite markers to examine genetic diversity in Stichopus cf. horrens throughout the Philippine archipelago, to aid species identification and clarify species boundaries. Phylogenetic analysis reveals two recently diverged COI lineages (Clade A and Clade B; c. 1.35–2.54 Mya) corresponding to sequence records for specimens identified as S. monotuberculatus and S. horrens, respectively. Microsatellite markers reveal two significantly differentiated genotype clusters broadly concordant with COI lineages (Cluster 1, Cluster 2). A small proportion of individuals were identified as later-generation hybrids indicating limited contemporary gene flow between genotype clusters, thus confirming species boundaries. Morphological differences in papillae distribution and form are observed for the two species, however tack-like spicules from the dorsal papillae are not a reliable diagnostic character. An additional putative cryptic species was detected within Clade B-Cluster 2 specimens warranting further examination. We propose that these lineages revealed by COI and genotype data be referred to as Stichopus cf. horrens species complex. © The Author(s) 2024.
Reef location and season, but not recruitment substrate contour and composition, affect coral recruitment patterns
dela Cruz, Dexter W.; Harrison, Peter L. (Elsevier B.V., 2024)
Most studies have quantified coral recruitment using recruitment tiles temporarily deployed on reefs. However, the wide range of tile types used in different studies potentially influences recruitment patterns thereby hindering accurate comparisons among reef areas. We examined the effect of different tile types with different surface structure and composition on spatial (reef locations) and temporal (season) patterns of coral recruitment in the northwestern Philippines. Dead coral skeleton, terracotta, and fibre-cement tiles were deployed and retrieved quarterly over a 15-month period. In contrast to previous studies, patterns of standardized density and composition of recruits were consistent among tile types. Recruits varied spatially and were highest in Caniogan reef, followed by Cory reef and Lucero reef, suggesting that coral recruitment in the Bolinao-Anda Reef Complex (BARC) is influenced by reef location and existing coral cover. Highest recruitment was also found during the peak coral spawning season. The results of this study contrast with some previous reports which indicate that coral recruitment patterns are strongly influenced by recruitment substrate types. Our study suggests that once sufficient biological conditioning of the tile surfaces has occurred, the microbial and algal community present on the different tile surfaces are similarly conducive to larval settlement of some coral taxa. © 2024 The Authors
Trace metals in phytoplankton: Requirements, function, and composition in harmful algal blooms
Manic, Dolly; Redil, Richard; Rodriguez, Irene (Multidisciplinary Digital Publishing Institute (MDPI), 2024)
In a constantly changing environment brought about by the climate crisis and escalated anthropogenic perturbations driven by the growing population, harmful algal bloom dynamics and their impacts are expected to shift, necessitating adaptive management strategies and comprehensive research efforts. Similar to primary productivity, HABs have been thought to be driven primarily by major nutrients such as N, P, and Si. However, recent investigations on the role and importance of micronutrients as limiting factors in aquatic environments have been highlighted. This paper provides a review of metal and phytoplankton interactions, with a specific emphasis on pertinent information on the influence of trace nutrients on growth, toxin production, and other underlying mechanisms related to the dynamics of HABs. Low to near-depleted levels of essential nutrients, including Fe, Cu, Zn, Se, Mn, Co, and Mo, negatively impact cell growth and proliferation of various marine and freshwater HAB species. However, evidence shows that at elevated levels, these trace elements, along with other non-essential ones, could still cause toxic effects to certain HAB species manifested by decreased photosynthetic activities, oxidative stress, ultrastructure damage, and cyst formation. Interestingly, while elevated levels of these metals mostly result in increased toxin production, Co (i.e., yessotoxins, gymnodimine, and palytoxins) and Mn (i.e., isodomoic acid, okadaic and diol esters) enrichments revealed otherwise. In addition to toxin production, releasing dissolved organic matter (DOM), including dissolved organic carbon (DOC) and humic substances, was observed as an adaptation strategy, since these organic compounds have been proven to chelate metals in the water column, thereby reducing metal-induced toxicity. Whilst current research centers on free metal toxicity of specific essential elements such as Cu and Zn, a comprehensive account of how trace metals contribute to the growth, toxin production, and other metabolic processes under conditions reflective of in situ scenarios of HAB-prone areas would yield new perspectives on the roles of trace metals in HABs. With the growing demands of the global population for food security and sustainability, substantial pressure is exerted on the agriculture and aquaculture sector, highlighting the need for effective communication of information regarding the interactions of macro- and micronutrients with HABs to improve existing policies and practices. © 2024 by the authors.