Handbook of mangroves in the Philippines - Panay

A 106-page guide is a user-friendly presentation of technical botanical description and illustrations of Philippine mangrove species in Panay Island, Guimaras and Aurora Province. Vegetative and reproductive structures of 34 mangrove species that are readily observed in the field are emphasized and presented in color photographs and as graphic icons. Also discussed: importance of mangroves; mangrove decline and legislation; conservation and rehabilitation; and mangrove-friendly aquaculture

Stock enhancement of the mud crabs Scylla spp. in the mangroves of Naisud and Bugtong Bato, Ibajay, Aklan, Philippines

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Oxygen, sulphide and nutrient uptake of the mangrove mud clam Anodontia edentula (Family: Lucinidae)

Oxygen, sulphide and nutrient (ammonia, nitrite and phosphate) uptake of Anodontia edentula was measured. Oxygen and sulphide were measured from sealed containers provided with 1 l fresh mangrove mud (sulphide source) and seawater (oxygen source) with two treatments (with and without clam) at 16 replicates each. Oxygen, sulphide and other parameters were measured at days 1 (initial), 3 and 5 (final). Nutrients were measured from containers filled with 1.5 l wastewater from a milkfish broodstock tank with two treatments (with and without clam) at eight replicates each. Ammonia, NO2 and PO4 were measured at days 0 (initial) 3, 6, 9 and 12 (final). Results showed significantly decreasing oxygen and sulphide concentrations in treatment with clams (ANOVA, p < 0.001). A significantly higher ammonia concentration (ANOVA, p < 0.05) was observed in treatment with clams while no significant difference was observed in nitrite and phosphate between the two treatments. A decreasing ammonia and an increasing nitrite trend was also observed in both treatments starting at day 3

Size and diel differences in activity patterns of Metapenaeus ensis, Penaeus latisulcatus and P. merguiensis

The nursery function of mangroves as shelter has been postulated to explain the positive correlation between shrimp catches and mangrove area. This study was undertaken to document shelter use and other activities in mangrove‐associated penaeids and to determine diel and size differences relating to these activities. Juvenile Metapenaeus ensis, Penaeus latisulcatus and P. merguiensis collected from mangrove areas in Guimaras, central Philippines and stocked individually in glass tanks (= replicates) provided with artificial shelters and sand substrate were observed every hour for 25 h. Size classes tested were very small (1–5.9 mm carapace length); small (6–10.9mm CL); medium (11–15.9mm CL); large (16–20.9mm CL); and very large (21–25.9 mm CL). Due to limited juvenile supply, only 3 sizes were tested for each species: P. merguiensis (very small to medium), M. ensis (small to large) and P. latisulcatus (medium to very large) with 5 replicate animals (one per tank) per size. Juvenile M. ensis and P. latisulcatus showed a strong diel periodicity of daytime burial and nocturnal activity. In contrast, P. merguiensis showed active swimming and feeding throughout the day and night. Very small to small P. merguiensis were observed on the shelters, but burying was exhibited only by a few medium‐sized juveniles. This shelter use is consistent with observations of small P. merguiensis entering the mangrove forest (where roots, twigs, etc. contribute to structural complexity) on the flood tide and concentrating in the shallow, turbid waters of adjoining creeks during ebb tide and slack water

Gill structure, anatomy and habitat of Anodontia edentula: Evidence of endosymbiosis

Surveys and interviews were conducted to determine sources and habitat of Anodontia edentula. Results showed that they inhabit muddy substrate of mangrove areas or the adjacent mudflats, burying at 20-60 cm deep in the mud. They are strategically situated in the sulfide-rich, low-oxygen layer of the substrate but have access to oxygen through their inhalant tube; both sulfide and oxygen are essential for their survival. Study of the clam s gross anatomy revealed thick, fleshy, deep purple to blackish brown gills; reduced digestive structure; and a highly elastic foot capable of extending several times longer than its body length. These observations conform with the anatomy of fellow lucinid clams. Furthermore, scanning electron micrographs showed coccoid or spherical bacteria occupying bacteriocytes in the clam s gills. Intermediate cells separating bacteriocytes observed in other lucinids were also noted in the SEM

Effect of salinity on survival of Metapenaeus anchistus juveniles and subadults

Survival of Metapenaeus anchistus (De Man) juveniles and subadults at 5, 15, 25, 35 (control) and 45 ppt salinity levels was determined and compared. Salinity levels lower than 35 ppt level were prepared by diluting pure seawater with tap water (OPPT) while 45 ppt level was prepared by diluting 85 ppt water with tap water. Survival was observed at 0.5, 1, 2, 3, 6, 12, 18, 24 h after stocking and every 12 hours thereafter until 96 h. Shrimp survival was highest at 35 ppt (P<0.01); differences among treatments were first observed at 2 h after exposure with some shrimps dying at 5 ppt. At the end of the experiment, survival was highest at 35 ppt (100%), followed by 25 and 45 ppt (90 and 80%, respectively), 15 ppt (50%) and 5 ppt (0%)

Single and mixed species of microalgae as larval food for the tropical sea cucumber Holothuria scabra

Different microalgae as larval food for Holothuria scabra, a high-value sea cucumber species with hatchery technology continually being refined to improve production, were studied. Two experiments were conducted to determine the performance of the larvae—first, the use of single-algal diet of either Chaetoceros calcitrans, Rhodomonas sp., or Tetraselmis tetrathele as feed; and second, the use of a combination of two algal species, C. calcitrans + Rhodomonas sp., C. calcitrans + T. tetrathele, or Rhodomonas sp. + T. tetrathele as feed. For both experiments, hatched larvae at 2 days post-fertilization (DPF) were used for initial stocking at a density of 200 larvae L−1. Growth, development, and survival were monitored until more than 50% of the larval population were considered as competent larvae (late auricularia). In the first experiment, during the early stage of development (early aricularia), larvae fed Rhodomonas sp. were larger compared to other treatments. However, when the larvae reached middle and late auricularia, they performed better when fed with C. calcitrans. Those larvae fed with C. calcitrans were significantly larger and showed faster development to competent larvae. In the second experiment, larvae fed mixed C. calcitrans + Rhodomonas sp. showed better performance in growth, development, and survival. The present study showed that C. calcitrans, when used solely as feed or in combination with Rhodomonas sp., promoted better growth, development, and survival of H. scabra larvae

Baseline assessment of fisheries for three species of mud crabs (Scylla spp.) in the mangroves of Ibajay, Aklan, Philippines

The full text is free.Stock enhancement through habitat restoration and habitat release have both been considered as approaches to the management of declining Scylla spp. Prior to stock enhancement trials, the present study was conducted to monitor recruitment and yields of three Scylla spp. in ∼70 ha of natural mangroves in Aklan, Panay, Philippines. Results showed that Scylla olivacea (Herbst, 1796) was the most abundant mud crab species, comprising 95% of the catches over the 4 yr sampling period. Size distribution for this species indicated year-round recruitment with peaks in the numbers of smaller, immature crabs during the summer months. The decreasing mean size at capture, yield and CPUE in terms of weight throughout the 4-yr sampling period is an indication that the area has been subjected to heavy fishing pressure. The constant CPUE in terms of numbers of crabs suggests that recruitment is constant, though this is likely to be lower than in other mangrove areas due to the topography of the site with limited access to the open sea, resulting in relatively low crab abundance and yields. Combined with the fidelity of S. olivacea to the mangrove habitat, this indicates a suitable population for investigation of the effectiveness of a hatchery-release program.This study was supported by EU-INCO contract IC-CT-2001-10022. We thank the crab collectors in the villages of Naisud and Bugtong Bato, Ibajay, Aklan for collecting crabs during sampling regardless of time and weather, J. Altamirano, J. Inguillo, R. Ramos, W. Sayson, and A. Traje for the assistance with mapping the study site