Substrate preference for burying and feeding of sandfish Holothuria scabra juveniles

Substrate preference for both burying and feeding of sandfish Holothuria scabra juveniles (3–6 g wet body weight) and their associated daily behavior, growth and survival were investigated in laboratory and field experiments using different coastal substrate types (silty mud, sandy mud, and coarse sand) to determine the ideal habitat for potential grow-out culture, sea ranching or stock enhancement of this important sea cucumber species. During the peak hours of burying (03:00–09:00 h) and feeding (15:00–03:00 h), a significantly greater number of sandfish juveniles preferred to bury in (28.3%) and feed on (21.5%) sandy mud, typical of intertidal coastal sand flats. Silty mud was the least preferred substrate for feeding (13.5%) and burying (13.8%). Burying and feeding preferences of sandfish juveniles were not significantly influenced by the presence of seagrass (Thalassia hemprichii) on coarse sand. Growth of sandfish juveniles in the first two weeks of rearing in tanks was significantly greater on coarse sand (growth rate: 0.59 g d−1 or 7.0% d−1), followed by sandy mud (0.34 g d−1 or 4.72% d−1) while OM content of these sediments remain almost unchanged. On silty mud, sandfish juveniles constantly shrunk (−0.02 g d−1 or −0.63% d−1) for 8 weeks while sediment OM content increased. In the field, silty mud substrate of a mangrove pond caused total mortality of sandfish within two weeks, while sandy mud substrate of a sand flat provided significantly higher growth than the control (no sediment), but not significantly different than coarse sand of a seagrass bed. Sandy mud to coarse sand substrates of intertidal sand flats were most preferred by sandfish juveniles while silty mud associated with muddy mangroves and culture ponds seems to be unsuitable that sandfish would opt to avoid. Our results will contribute to the selection of suitable sites for sandfish sea ranching and stock enhancement in coastal areas.This study was funded by the Australian Centre for International Agriculture Research (ACIAR) through the project FIS/2010/042 “Expansion and Diversification of Production and Management Systems for Sea Cucumbers in the Philippines, Vietnam and northern Australia”. In-house support was provided by SEAFDEC/AQD through studies FS-10-Y2010T and BR-03-Y2011T. Special thanks to M.R. Banaticla-Altamirano for improving this manuscript and to the reviewers and editors for the constructive comments. We also appreciate the assistance of H. Figurado in monitoring in the lab and at the field

Effects of UV-treated sea water, chlorinated sea water, and formalin-treated copepods on survival and growth of newborn seahorses, Hippocampus comes

Seed production of the seahorse Hippocampus comes was examined using different types of sea water (UV-treated, chlorinated, sand-filtered), and formalin-treated copepod Pseudodiaptomous sp. as a food organism. Growth and survival of newborn seahorses (8.9±0.0 mm stretched height, 0.004 g) were monitored until day 30 after birth. Growth (stretched height and weight) was significantly higher (p<0.05) in UV-treated sea water (41.4±0.5 mm, 0.23±0.00 g) than in chlorinated (33.8±1.4 mm, 0.16±0.00 g) or sand-filtered (32.8±0.1 mm, 0.16±0.00 g) sea water. Survival was significantly higher in UV-treated (65.6±1.1%) and chlorinated (62.2±4.0%) sea water than in sand-filtered sea water (41.1±1.1%). Survival of seahorses fed 30 ppm formalin-treated copepods (95.3±1.8%) was significantly higher (p<0.05) than of seahorses fed untreated copepods (78.7±5.5%) on day 8. On day 15 survival was 78.7±9.68% in seahorses fed formalin-treated copepods and 0% in those fed untreated copepods. By day 30, survival of seahorses fed formalin-treated copepods was 64.7±9.82%. On the day of the final comparison (day 10), there was no difference in size between groups. Thus, the present study demonstrates that survival and growth of newborn seahorses is significantly improved in UV-treated water, and survival is markedly maintained by treating food organisms in formalin.The authors thank the anonymous reviewer for helpful comments and suggestions for improving the manuscript. The authors also thank Rod Salvador Tibubos and Arnel Abaricio for their assistance in the maintenance of the seahorses. This study was funded by SEAFDEC/AQD under Study Code BR-02-F2007T, Contribution No. 2011-02, and by the Government of Japan Trust Fund (GOJ-TF) Stock Enhancement Program under the project title “Resource Enhancement of Internationally Threatened and Over-Exploited Species in Southeast Asia through Stock Release”

DESIGN OF AN IOT-BASED SMALL SCALE INDOOR HYDROPONICS WITH GEO-SOLAR SYSTEM

International audienceUrban farming is considered trending. Hydroponics, in particular, offers opportunities to grow and produce healthy plants with lesser energy requirements. In this work, the necessary requirements for plant growth and development such as temperature, humidity, pH, nutrient level and water temperature were being studied as bases for making the controlling and monitoring system. The outcome of this work indicates the selection of sensors through compare and contrast functions as set in the program. Data gathered were processed and programmed using microcontrollers and open-source software (Arduino and Blynk). Specifically, the solar photovoltaic (PV) and geothermal systems were utilized to provide power and maintain the temperature of the whole system. Based on the results, the design and selection of appropriate sensors and devices were able to monitor and control the required nutrients and environment of a plant. The integration also of solar PV was able to power up the whole system sustaining the operations of the devices. The integration also of the ground heat exchanger system helped in reducing the temperature to an average of 5oC. Moreover, the system was able to display the plant’s parameters and prompt the owner of any irregularities in the system. It can be recommended to improve further the structural design and assembly of the system