Davao del Norte State College

Davao, Philippines

Davao del Norte State College

Davao, Philippines
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Concepcion C.B.,West Virginia University | Dumandan P.T.,University of the Philippines at Mindanao | Silvosa M.R.,Davao Del Norte State College | Bildstein K.L.,Hawk Mountain Sanctuary | And 2 more authors.
Journal of Raptor Research | Year: 2017

Raptor migration rarely involves long-distance movements across open oceans. One exception occurs along the East-Asian Oceanic Flyway. We collected migration data at two terrestrial hawkwatch sites along this flyway to better understand open-ocean movements along this largely overwater corridor. At the northern end of the Philippines, at Basco on the island of Batan, we recorded 7587 migratory raptors in autumn 2014. Near the southern end of the Philippines, at Cape San Agustin on the island of Mindanao, we recorded 27,399 raptors migrating in autumn 2012. Chinese Sparrowhawks (Accipiter soloensis) were the most common raptors observed, making up approximately 89% and 92% of total records for Basco and Cape San Agustin, respectively. The Grey-faced Buzzard (Butastur indicus) was the second most common raptor migrant, accounting for 8% of the total counts at both watch sites. The migration period was about 1-2 wk earlier at Basco, the more northerly site, than at Cape San Agustin. Overwater flights at Basco peaked in both the morning and late afternoon, whereas at Cape San Agustin there was only a morning peak. In general, the rate of migration passage at both sites was highest with clear skies when winds were blowing from the northwest. However, we observed interspecific differences in migration behavior at both sites, with Accipiters more likely to be observed with tailwinds and eastward winds, and Grey-faced Buzzards more likely observed with headwinds. These results help to characterize poorly known aspects of raptor biology and to identify potential migratory bottlenecks or key sites for raptor conservation in little-studied Philippine tropical ecosystems. © 2017 The Raptor Research Foundation, Inc.


Bos A.R.,American University in Cairo | Bos A.R.,Naturalis Biodiversity Center | Bos A.R.,Davao del Norte State College | Hoeksema B.W.,Naturalis Biodiversity Center | Hoeksema B.W.,Leiden University
Raffles Bulletin of Zoology | Year: 2017

Mushroom corals (Fungiidae) have rarely been studied in the southeast of the Philippines and even less studies have reported fish fauna associated with fungiids. The present study provides a species overview, relative abundance, and associated fish and invertebrate fauna of the mushroom corals from the Davao Gulf (southeast Mindanao). Thirty-three mushroom coral species belonging to 13 genera were recorded with Danafungia horrida being the most common coral with a relative frequency of 20.4%. By two additional records from previous studies, the mushroom coral fauna of southeastern Mindanao consists of at least 35 species, placing it in the centre of the Coral Triangle. The reports of the poorly-known species Podabacia sinai and Sandalolitha boucheti constitute first records for the Philippines, hence range extensions for both species. Furthermore, six rare species were encountered: Cycloseris mokai, Halomitra clavator, Heliofungia fralinae, Lithophyllon spinifer, Pleuractis gravis, and Podabacia motuporensis. The associated cryptofauna consisted predominantly of fish, shrimps, and acoel flatworms. Commensal fish were mainly represented by the Gobiidae and Tripterygiidae, with the goby Eviota rubriceps dwelling on 17 mushroom coral species, being the most common associated fish species. The largemouth triplefin Ucla xenogrammus was encountered twice on individuals of Pleuractis paumotensis. Apart from the commensal shrimps Cuapetes lacertae, C. kororensis, and the acoel flatworm Waminoa sp., unidentified brittle stars (Ophiuroidea), and a crab were found in association with mushroom corals. This study resulted in new records of associated fauna for Fungiidae, whereas cryptobenthic species of various other taxa have been reported from mushroom corals studied elsewhere. Based on the diversity of Fungiidae in the central Philippines and other areas in the Coral Triangle, it may be expected that the species list of the Davao Gulf may be further expanded in the future. © National University of Singapore.


Bos A.R.,American University in Cairo | Bos A.R.,Naturalis Biodiversity Center | Bos A.R.,Davao del Norte State College | Smits H.M.,Hydromax
Marine Biodiversity Records | Year: 2013

Several specimens of the pseudochromid Manonichthys alleni, with total length ranging from 45 to 60 mm, were observed at depths of 19-28 m in a coral reef in the Davao Gulf in the southern Philippines. Each specimen lived within a separate colony of the tubular sponge Callyspongia aeri-Ausa. This constitutes the first record in the Philippine archipelago of a dottyback so far only known from Indonesian and Malaysian waters. © Marine Biological Association of the United Kingdom 2013.


Relox P.E.,Davao del Norte State College | Castillo-Israel K.A.T.,University of the Philippines at Los Baños | Serrano E.P.,University of the Philippines at Los Baños | Absulio W.L.,University of the Philippines at Los Baños | Gandia J.B.L.,University of the Philippines at Los Baños
International Food Research Journal | Year: 2015

The study was conducted to determine the efficacy of 1-methylcyclopropene (1-MCP) postcutting treatment on fresh-cut 'Sinta' papaya (Carica papaya L. cv. 'Sinta') in maintaining its storage quality using two packaging forms commonly used commercially namely PET plastic tray wrapped with LDPE stretchable plastic film, and PET clamshell plastic containers. Freshcut 'Sinta' papaya cubes at Peel Colour Index 5 (yellow with tinge of green) were packaged using plastic tray wrapped with plastic film and clamshell plastic containers.1-MCP gas was introduced post-cutting inside the packaging to a final concentration of 2.5 nL L-1. The freshcuts were stored at 10°C and 95% RH. Samples were evaluated for headspace C2H4 (HS-C2H4), headspace CO2 (HS-CO2), polygalacturonase (PG) activity, total reducing sugars, firmness, color (as luminosity), water-soaking, visual quality rating (VQR) and microbial load. In both packaging types, lower PG activity and total reducing sugars were observed in 1-MCP treatments compared with controls at certain storage days. In plastic tray-film packaging, lower HS-C2H4 levels were observed in 1-MCP treated fresh-cuts compared with the control. In clamshell packaging, significant differences in water-soaking, luminosity and VQR at days 2 and 3 were observed between 1-MCP treated and control fruits. All of the treatments, on day 2 of storage, complied with European Union countries' limits on aerobic plate counts (7 log), yeasts and molds counts (5 log) and coliform counts (3 log). To the best of our knowledge, this is the first study on the efficacy of 1-MCP post-cutting treatment on fresh-cut papaya of the 'Sinta' variety and also the use in a 1-MCP study of the packaging forms mentioned.


Gumanao G.S.,Davao del Norte State College | Saceda-Cardoza M.M.,Davao del Norte State College | Mueller B.,Netherlands Institute for Sea Research | Bos A.R.,American University in Cairo | Bos A.R.,Naturalis Biodiversity Center
Journal of Applied Ichthyology | Year: 2016

Length-weight relationships (LWRs) of 139 coral reef and pelagic fish species (representing 34 fish families) were calculated based on 3806 individuals measured at local fish markets near the Davao Gulf in the southern Philippines during weekly visits between March 2009 and July 2011, as well as in June 2012. Fishes were caught with a variety of fishing methods, corroborated by abrasions and injuries. Forty-seven of 139 LWRs were firstly reported and new to science. The mean slope b of the LWRs was 3.035, indicating that the majority of studied species followed isometric growth. Standard length - total length relationships were calculated for all measured fish species. Additionally, standard length - fork length relationships are presented for 108 species. Moreover, fifteen new records of maximum fish length and weight are reported. © 2016 Blackwell Verlag GmbH.


Bos A.R.,Davao Del Norte State College | Bos A.R.,Netherlands Center for Biodiversity Naturalis | Bos A.R.,American University in Cairo | Gumanao G.S.,Davao Del Norte State College | And 3 more authors.
Invertebrate Reproduction and Development | Year: 2013

Mating of the relatively common sea star, Archaster typicus, provides an excellent opportunity to study maturation processes and behavioral differences between males and females, since monomorphism does not allow separation under normal conditions. The present study determined biological and behavioral features of males and females during the mating season in the Davao Gulf (Philippines). Thousands of pairs were observed in September and October 2008 with a mean density of 3 pairsm2. Around full moon, mean density reached 7 pairsm2, whereas during new moon very few pairs were found. Specimens reached maturity at a radius (R) of 29 mm, while mating specimens had a mean R of 35 mm. Two-thirds of the population were adults and about 35% participated in mating during each observation. Mean R of mating adults was constant throughout the mating season, but within pairs, males were significantly larger in September than in October. The locomotion rate increased with R from 40 to 60 cm min1 and there was no significant difference between males and females. The role of the lunar cycle as a trigger for reproduction and the significance of large males mating before small males are discussed. © 2013 Taylor & Francis.


Bos A.R.,American University in Cairo | Bos A.R.,Naturalis Biodiversity Center | Bos A.R.,Davao del Norte State College
Raffles Bulletin of Zoology | Year: 2014

The goatfish, Upeneus nigromarginatus, new species, is described based on five specimens (151–196 mm) purchased at a fish market in Panabo City, Mindanao, Philippines. This species is diagnosed by the following counts and external morphology: dorsal fin rays (VIII, 9–10), pectoral fin rays (16), lateral line scales (36–37), total number of gill rakers (25–26), and anal fin rays (I–II, 6). When compared to congeners, U. nigromarginatus, new species has a relatively deeper body (31.1–34.8% in SL vs <30% in SL), shorter snout (7.1–9.0% in SL vs >9.6% in SL), and longer pectoral fin (27.7–29.1% in SL vs <25% in SL). Upeneus nigromarginatus, new species, has neither stripes on the body, nor bands on the caudal fin. However, a black band borders the distal edges of both the first and second dorsal fins, and at the posterior edge of the upper lobe of the caudal fin; hence the proposed common name ‘black-margined goatfish’. The posterior edge of the ventral caudal lobe has a white margin. The comparisons of a fragment of the cytochrome C oxidase subunit I (COI; 28 specimens representing 10 Upeneus species) and 34 morphometric parameters (Principle Component Analysis; 56 specimens representing five genera and 12 mullid species) supported the description of U. nigromarginatus, new species. © National University of Singapore.


van Katwijk M.M.,Radboud University Nijmegen | Bos A.R.,Radboud University Nijmegen | Bos A.R.,Davao del Norte State College | Kennis P.,Radboud University Nijmegen | de Vries R.,Radboud University Nijmegen
Biological Conservation | Year: 2010

A semi-annual eelgrass (Zostera marina L.) population became extinct in 2004. It had flourished for many decades at Terschelling in the western Wadden Sea, one of the most eutrophied locations where seagrass growth has been recorded. Semi-annual populations survive the winter season by seed (annual), and by incidental plant survival (semi-annual). We compared seed bank dynamics and fate of plants between this impacted site and a reference site in the winter of 1990-1991. Seed bank density at Terschelling was extremely low (5-35 seeds m-2) in comparison to the reference site (>60 seeds m-2) and also in comparison to seed bank densities of (semi-)annual eelgrass populations in other parts of the world. Plant survival during winter was nil. Nevertheless, the population more than doubled its area in 1991, implying maximum germination and seedling survival rates. However, from 1992 onwards the decline set in and continued - while the nutrient levels decreased. To establish the cause of the low seed bank density, we conducted a transplantation experiment in 2004 to study the relationship between seed production and macro-algal cover. The transplantation experiment showed a negative relationship between the survival of seed producing shoots and suffocation by macro-algae, which is associated with light limitation and unfavourable biogeochemical conditions. The plants died before they had started to produce seeds. Thus, it is likely that macro-algal cover was responsible for the low seed bank density found in Terschelling in 1990-1991. Both the recorded low seed bank density and absence of incidental plant survival during winter were related to eutrophication. These parameters must have been a severe bottleneck in the life history of the extinct population at the impacted site, particularly as Z. marina seed banks are transient. Therefore we deduce that this population had survived at the edge of collapse, and became extinct after a small, haphazard environmental change. We argue that its resilience during these years must have been due to (i) maximum germination and seedling survival rates and (ii) spatial spreading of risks: parts of the population may have survived at locally macro-algae-free spots from where the area could be recolonised. As a consequence, the timing of the collapse was unpredictable and did not synchronise with the eutrophication process. The lesson learnt for conservation is to recognise that eutrophication may be a cause for seagrass population collapse and its eventual extinction, even years after nutrient levels stabilised, or even decreased. © 2009 Elsevier Ltd. All rights reserved.


van Katwijk M.M.,Radboud University Nijmegen | Bos A.R.,Radboud University Nijmegen | Bos A.R.,Davao del Norte State College | Hermus D.C.R.,Radboud University Nijmegen | Suykerbuyk W.,Radboud University Nijmegen
Estuarine, Coastal and Shelf Science | Year: 2010

Seagrasses are well-known ecosystem engineers. They reduce water dynamics and sediment resuspension, and trap fine sediments. However, exceptions of this paradigm have been reported. To test whether these exceptions could be related to plant cover and environmental conditions, we investigated sediment modification under influence of seagrass presence in various annual eelgrass (Zostera marina) beds with varying plant cover and sediment composition.At the relatively wave-exposed, sandy sites, dense vegetation caused muddification (increase in fine sediments and organic content) of the sediments. Sparse vegetation (<35% cover) had no effect, as such confirming the classical sediment trapping paradigm. In contrast, at the sheltered sites with muddy sediments, dense vegetation had no effect on the sediment composition, and in sparse vegetation sandification (decrease in fine sediments and organic content) was recorded. Sandification was never recorded before and was probably related to turbulence enhancement.Both, muddification and sandification are likely to provide a feedback on seagrass performance. Muddification may increase the nutrient input and, depending on the nutrient status of the system, either stimulate or reduce seagrass development. Similarly, sandification may postpone and even prevent extinction of seagrass beds when it occurs in areas that may have become too muddy for seagrass growth. © 2010 Elsevier Ltd.

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