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Davao, Philippines

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

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. Source

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

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. Source

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

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. Source

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

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. Source

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

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. Source

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