Now showing items 1-20 of 28

    • Conference paper

      Ability of sandfish (Holothuria scabra) to utilise organic matter in black tiger shrimp ponds 

      S Watanabe, M Kodama, JM Zarate, MJH Lebata-Ramos & MFJ Nievales - In CA Hair, TD Pickering & DJ Mills (Eds.), Asia-Pacific tropical sea cucumber aquaculture. Proceedings of an international symposium held in Noumea, New Caledonia, 15-17 February 2011, 2012 - Australian Centre for International Agricultural Research
      Series: ACIAR Proceedings; No. 136
      Due to frequent viral disease outbreaks, a large proportion of shrimp aquaculture in South-East Asian countries has switched from black tiger shrimp (Penaeus monodon) to P. vannamei, an exotic species originally imported from Latin America. One of the causes of disease outbreaks is thought to be poor water and sediment conditions in the shrimp ponds, which may aggravate disease symptoms. To obtain basic information for co-culture methods of black tiger shrimp and sandfish (Holothuria scabra) for possible mitigation of shrimp-pond eutrophication and prevention of disease outbreaks, basic laboratory experiments were conducted at the Southeast Asian Fisheries Development Center—Aquaculture Department in Iloilo, the Philippines. A feeding trial of juvenile sandfish showed that they do not grow well with fresh shrimp feed on hard substrate. Another trial indicated that sand substrate enhances the growth of juvenile sandfish fed with shrimp feed. A feeding trial using shrimp tank detritus, shrimp faeces and Navicula ramosissima (a benthic diatom) as food sources showed that sandfish grew fastest with the faeces, followed by detritus and N. ramosissima. Dissolved oxygen consumption and acid-volatile sulfur levels in the shrimp tank detritus were reduced by sandfish feeding. This suggests that sandfish are capable of growing with organic matter in shrimp ponds, and can bioremediate shrimp-pond sediment.
    • Article

      Apparent digestibility coefficient of nutrients from shrimp, mussel, diatom and seaweed by juvenile Holothuria scabra Jaeger 

      ZGA Orozco, JG Sumbing, MJH Lebata-Ramos & S Watanabe - Aquaculture Research, 2014 - Wiley
      The ability of Holothuria scabra to digest nutrients, such as organic matter (OM), protein and carbohydrate from animal and plant feed ingredients was investigated. Four test feeds prepared by mixing sand with single ingredients from animal sources (shrimp and mussel) and plant sources (diatom and seaweed) were fed to H. scabra to estimate apparent digestibility coefficient (ADC). The total assimilated nutrient (TAN) increased with ADC, whereas ingestion rate (IR) varied slightly among the feeds suggesting that ADC might be a good indicator of nutrient availability to H. scabra. The ADCOM of shrimp and mussel was significantly higher than that diatom and seaweed: 86.2%, 77.1%, 55.1% and 32.3% respectively. ADCprotein was similar for shrimp (88.7%), mussel (84.8%) and diatom (75.2%), but significantly lower in seaweed (34.4%). ADCcarbohydrate was similar in mussel (58.5%) and diatom (58.3%) as well as in seaweed (31.6) and shrimp (28.0%). ADCprotein was relatively higher than ADCcarbohydrate suggesting that H. scabra generally digests more protein than carbohydrate. Furthermore, results indicated that nutrients from animal-based feeds are more efficiently digested by H. scabra; thus, animal ingredients rich in easily digestible protein could potentially provide an efficiently balanced diet for H. scabra fed with diatom containing high easily digestible carbohydrate.
    • Article

      Approaches to stock enhancement in mangrove-associated crab fisheries 

      L Le Vay, MJHL Lebata, M Walton, JH Primavera, ET Quinitio, CR Lavilla, FD Parado-Estepa, E Rodriguez, VN Ut, TT Nghia, P Sorgeloos & M Wille - Reviews in Fisheries Science, 2008 - Taylor & Francis
      Over the last decade, hatchery production of mud crabs has become technically and economically more feasible, enabling evaluation of the potential effectiveness of hatchery release in fisheries enhancement. The high growth rates and limited movement of released crabs means that fisheries’ yields an isolated mangrove systems with restricted recruitment can be enhanced with a few months. Thus, a release program may be an effective strategy for short-term enhancement in carefully selected specific areas. To date, results are very promising; with recovery rates up to 50% and increases in fisheries’ yield up to 46% over baseline catches. In contrast, mark-recapture studies in more open mangrove system populations shows that recruitment success and subsequent stock abundance may be largely determined by habitat availability. For these populations, restoration of lost o degraded mangrove areas has been show to be effective in promoting stock recovery through natural recruitment, with replanted mangroves supporting fisheries of equivalent economic value to that of natural mangroves, though it may take some years to reach these levels. Thus, a balanced approach to stock management could integrate both hatchery-release and habitat restoration programs, depending on local conditions and over different thin scales, with parallel-co-management to support effectiveness.
    • Article

      Assessment of the effectiveness of mangrove rehabilitation using exploited and non-exploited indicator species 

      ME Walton, L Le Vay, JH Lebata, J Binas & JH Primavera - Biological Conservation, 2007 - Elsevier
      Mangrove forests have been cleared at an alarming rate over the last century to allow space for settlements, agriculture and aquaculture and are still used today for fuel and construction. However, in the last few decades the value of the range of services and products that mangroves supply are being increasingly appreciated by policy makers. Mangrove replanting is frequently used as a method of restoring ecological function and associated goods and services but this may not be justified as once diverse forests are often replanted with mono-genus stands. In the present study the abundance of the commercially important mud crab Scylla olivacea, a top benthic predator, was used as an indicator of the ecological function of mangrove habitats. Abundance was estimated using catch per unit effort (CPUE) data obtained from an experimental standardized trapping grid. The same commercial traps also catch two other smaller non-exploited competing species, Baptozius vinosus and Thalamita crenata that are discarded by fishers. The relative abundance of these three species was used to separate the effects of habitat from fishing pressure and recruitment limitation. Four sites on Panay Island, central Philippines were selected to represent different types of mangrove habitat; a replanted fringing area predominantly of Rhizophora spp., a natural fringing area predominantly of Sonneratia spp., a diverse natural basin mangrove area and a degraded mangrove site. The relative abundance of mud crabs was found to be equivalent in the natural fringing mangrove (1.89 crabs trap−1 day−1) and the replanted mangrove area (1.71 and 0.81 crabs trap−1 day−1). Lower densities of S. olivacea in the basin mangrove area (0.33 crabs trap−1 day−1) appear to be due to limited recruitment, and at this site there was instead a higher abundance of the other non-commercial crab species. No mud crabs were caught in the degraded mangrove area and CPUE for other crab species was also low. Overall, the study suggests that replanting of mangroves even in mono-genus stands was effective in restoring mud crab populations, indicating recovery of an ecological function to a level equivalent to that of natural mangrove environments. The use of CPUE as an indictor of relative abundance of S. olivacea was supported by single release mark–recapture studies and a multiple release mark–recapture study in the replanted mangrove site.
    • Article

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

      MJHL Lebata, L Le Vay, JH Primavera, ME Walton & JB Biñas - Bulletin of Marine Science, 2007 - University of Miami, Rosenstiel School of Marine and Atmospheric Science
      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.
    • Book chapter

      Co-culture trials of sandfish Holothuria scabra and black tiger shrimp Penaeus monodon in mangroves 

      MJH Lebata-Ramos, EFD Solis, RC Sibonga & S Watanabe - In K Tanaka, S Morioka & S Watanabe (Eds.), Sustainable stock management and development of aquaculture technology suitable for Southeast Asia, 2012 - Japan International Research Center for Agricultural Sciences
      Series: JIRCAS Working Report; No. 75
      To address its mandate to develop environment-friendly culture techniques, the Southeast Asian Fisheries Development Center, Aquaculture Department (SEAFDEC/AQD) is trying to establish a culture system in mangroves for commercially important aquaculture species. Recently, SEAFDEC/AQD has successfully produced sandfish, Holothuria scabra, in the hatchery. Using hatchery-bred juveniles, monoculture and co-culture trials are being conducted in ponds, pens and cages. This study investigated the feasibility of the co-culture of black tiger shrimp, Penaeus monodon, and H. scabra in the mangroves by comparing growth and survival in monoculture and co-culture conditions. Water and sediment quality were compared between treatments. Results showed that growth and survival of P. monodon (P. monodon only = 48.8±4.9%; P. monodon + H. scabra = 46.1±7.4%) and H. scabra (H. scabra only = 13.1±6.1%; P. monodon + H. scabra = 12.3±6.2%) grown together or separately did not significantly differ. P. monodon survivial was positively correlated while growth negatiely correlated with temperature. Feed input significantly increased sulfide levels in both treatments (P. monodon; P. monodon + H. scabra) and sulfide significantly differed between treatments with the highest concentration in P. monodon only, then P. monodon + H. scabra and H. scabra only. Ammonia concentrations followed the same trend as sulfide but did not significantly differ among treatments. P. monodon cultured in mangroves were not affected by the white spot syndrome virus which affected neighboring culture ponds. Results of these initial trials may not be conclusive yet but show a promising culture system for P. monodon that may be integrated with the mangroves.
    • Article

      Collection of the clam Anodontia edentula in mangrove habitats in Panay and Guimaras, central Philippines 

      JH Primavera, MJHL Lebata, LF Gustilo & JP Altamirano - Wetlands Ecology and Management, 2002 - Kluwer Academic Publishers
      The mangrove clam Anodontia edentula is highly prized in the Philippines for its flavor and large size. Because this infaunal species is found down to one meter deep in mangrove areas, harvesting the clam reportedly damages mangrove stands. To evaluate such reports, a survey of collection methods was undertaken in Panay and Guimaras, central Philippines in August 1997-December 1999. Host to chemosynthetic bacterial symbionts that utilize sulfide as energy source, A. edentula are strategically situated in sulfide-rich anoxic substrates but also gain access to oxygenated seawater through a ventilation burrow or tube. By locating the opening of this burrow, collectors can detect the presence of a buried clam and harvest it nondestructively with a blade or bare hands. In contrast, the indiscriminate tilling of wide mangrove areas can damage mangrove plants. Most collectors were 40-45 years old with 22-30 years collection experience, married with 5-7 children, and had low educational attainment. They sold clams directly in the local markets or through middlemen (to restaurants and beach resorts); sales provided from 10% to 100% of daily family income. Collectors complained of decreasing clam sizes and numbers and the physically strenuous work of collecting.
    • Article

      Diel activity patterns in Metapenaeus and Penaeus juveniles 

      JH Primavera & J Lebata - Hydrobiologia, 1995 - Springer Verlag
      Small (5–10.9 mm carapace length), medium (11–15.9 mm), and large (16–20.9 mm) juveniles of Metapenaeus anchistus, Metapenaeus sp., Penaeus monodon and P. merguiensis were stocked individually in glass tanks provided with sand substrate, sea water, artificial bamboo shelter, aeration and food. The seven activity types (recorded for each shrimp hourly for 24 h) were classified as below (burrowing) or above substrate (swimming, walking, stationary, in shelter, feeding and cleaning). Shrimp juveniles exhibited a strong diel periodicity — emergence and activity at night and burrowing in the day. The chi-square test showed that type of activity (above/below substrate) was associated with period (light/dark). Diurnal burrowing was greater among Metapenaeus than Penaeus; inversely, above substrate activities were more frequent for Penaeus species compared to Metapenaeus. Feeding was the major above substrate and nocturnal activity for M. anchistus, Metapenaeus sp. and P. monodon. Only P. Monodon used the shelter consistently. Frequency of the 7 activity types was dependent on juvenile size for Penaeus, e.g., the preference for shelters shifted to burrowing with increase in size in P. monodon. Results are discussed in relation to the importance of mangrove habitats in providing shelter to penaeids, in particular the mangrove-associated P. monodon and P. merguiensis.
    • Article

      Diet-tissue stable isotopic fractionation of tropical sea cucumber, Holothuria scabra 

      S Watanabe, M Kodama, JG Sumbing & MJH Lebata-Ramos - Japan Agricultural Research Quarterly, 2013 - Japan International Research Center for Agricultural Sciences (JIRCAS)
      To provide a basis for a stable carbon and nitrogen isotope ratio (δ13C / δ15N) analysis to determine the assimilated organic matter in sea cucumber, Holothuria scabra, diet-tissue fractionations were experimentally determined by mono-feeding rearing with diatom. While δ15N fractionation of the whole body wall (2.4‰) was similar to the commonly accepted value (2.6 - 4‰), δ13C fractionation of the body wall (4.2‰) showed considerable discrepancy with the commonly accepted value (0 - 1‰) due to the high content (35% dry wt/wt) of calcareous spicules (CaCO3) in the body wall, which had significantly higher δ13C (-8.6‰) than the organic fractions. Computational elimination of spicules based upon spicule content and spicule δ13C reduced the δ13C fractionation of the body wall to 1.5‰, close to the common value. δ13C fractionation after spicule removal by acid decarbonation and subsequent rinsing (3.2‰) did not agree with the common value, and δ15N fractionation was significantly elevated by decarbonation. δ15N and δ13C fractionations of the intestine (1.5 and 2.2‰, respectively) did not agree with the common values. Since δ13C and δ15N of the feces did not differ significantly from those of the diet, feces may be used to determine ingested organic matter in the wild.
    • Article

      Effect of salinity on survival of Metapenaeus anchistus juveniles and subadults 

      MJHL Lebata & J Primavera - UPV Journal of Natural Sciences, 1997 - University of the Philippines in the Visayas
      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%).
    • Article

      Elemental sulfur in the gills of the mangrove mud clam Anodontia edentula (Family Lucinidae) 

      JHL Lebata - Journal of Shellfish Research, 2000 - National Shellfisheries Association
      Different sizes of the mangrove mud clam Anodontia edentula were collected from the mangroves in Brgy. San Roque in Estancia, Iloilo, central Philippines, and the mantle, gill, and foot tissues were analyzed for elemental sulfur content. Mangrove mud (substrate) was also analyzed for total sulfur content to establish the possibility of clam-bacteria symbiosis in this lucinid clam. Sulfur analysis showed highly significant (p <0.0001) amounts of elemental sulfur in the gills (247.64 ± 63.28 μmoles/g FW) compared with the quantities observed in the mantle (0.84 ± 0.22 μmoles/g FW). Elemental sulfur was absent from the foot tissues. Results also showed a significantly (p <0.05) decreasing elemental sulfur from the newly collected clams (mean = 461.18 μmoles/g FW) compared to those reared in the laboratory (mean = 159.08 μmoles/g FW: with mangrove mud substrate; mean = 45.18 μmoles/g FW without substrate), which were analyzed weekly until week 3, indicating that stored elemental sulfur is being utilized by the bacteria in the absence of sulfide. Total sulfur content of mangrove mud in situ was higher than that used us substrate in the experiment; where there were no significant differences from initial to final readings. This shows that mangrove mud in situ is linked to a steady sulfur source.
    • Article

      Evaluation of hatchery-based enhancement of the mud crab, Scylla spp., fisheries in mangroves: comparison of species and release strategies 

      MJHL Lebata, L Le Vay, ME Walton, JB Biñas, ET Quinitio, EM Rodriguez & JH Primavera - Marine and Freshwater Research, 2009 - CSIRO Publishing
      Ranching, stock enhancement and restocking are management approaches involving the release of wild or hatchery-bred organisms to enhance, conserve or restore fisheries. The present study, conducted from April 2002 to November 2005, evaluated the effectiveness of releasing wild and hatchery-reared (HR) mud crabs in the mangroves of Ibajay, Aklan, Philippines where preliminary studies demonstrated declining fishery yields, abundance and size of crabs. Comparison of survival and growth of wild-released and HR Scylla olivacea and HR Scylla serrata demonstrated the effect of nursery conditioning, size-at-release and species differences. Overall yield and catch per unit effort (CPUE) increased by 46% after stock enhancement trials. Recapture rates of released crabs were highest in wild-released S. olivacea and in crabs measuring 65.0–69.9 mm carapace width (CW) and lowest in non-conditioned HR S. serrata. Growth rates were highest for conditioned HR S. olivacea and lowest for conditioned HR S. serrata (11.7 and 3.7 mm month-1 respectively). Fishing mortality was highest for S. olivacea, whereas natural mortality was greater for S. serrata. Conditioning hatchery-bred animals before release is also important in obtaining higher survival. S. olivacea was the more appropriate of the two species for release in mangrove habitats inundated with low-salinity water. However, there is a need for site-specific studies to evaluate the effectiveness of releases.
    • Conference paper

      Evaluation of nutritional condition of juvenile sandfish (Holothuria scabra) 

      S Watanabe, JM Zarate, MJH Lebata-Ramos & MFJ Nievales - In CA Hair, TD Pickering & DJ Mills (Eds.), Asia-Pacific tropical sea cucumber aquaculture. Proceedings of an international symposium held in Noumea, New Caledonia, 15-17 February 2011, 2012 - Australian Centre for International Agricultural Research
      Series: ACIAR Proceedings; No. 136
      It is important to accurately evaluate the wellbeing or nutritional condition of organisms when monitoring the wild stock conditions and improvement in aquaculture techniques; however, reliable nutritional condition indexes have not been established for sea cucumbers. In this study, the effects of starvation on condition factor (body weight / body volume), coelomic fluid constituent (protein, carbohydrate and cholesterol) concentrations and coelomic fluid density were analysed in an attempt to establish a method to determine nutritional condition in juvenile sandfish (Holothuria scabra). Body length, breadth and weight of juveniles produced at the sea cucumber hatchery of the Aquaculture Department, Southeast Asian Fisheries Development Center, were measured after anaesthetisation with 2% menthol-ethanol. Coelomic fluid protein level was analysed by the bicinchoninic acid method. Carbohydrate level was analysed by the phenol – sulfuric acid method. Cholesterol level was analysed by the Zak method. Coelomic fluid volume and coelomic fluid weight were measured. Starvation caused a concomitant decrease in body length, breadth and weight, resulting in no net change in the condition factor. This result indicated that condition factor cannot be used as a nutritional condition index. Coelomic fluid constituent level could be measured with a small volume of sample (i.e. 10–20 μL). Although no clear pattern was observed in coelomic fluid protein and cholesterol levels during the starvation trial, carbohydrate level increased, as did coelomic fluid density. These results suggest that coelomic fluid density and carbohydrate level may be used as indexes for nutritional condition of sandfish without sacrificing the animal.
    • Article

      Evaluation of post-release behavior, recapture, and growth rates of hatchery-reared abalone Haliotis asinina released in Sagay Marine Reserve, Philippines 

      MJH Lebata-Ramos, EFC Doyola-Solis, JBR Abrogueña, H Ogata, JG Sumbing & RC Sibonga - Reviews in Fisheries Science, 2013 - Taylor & Francis
      The lucrative returns brought by abalone fisheries have caused overexploitation and decline of the wild population. In the Philippines, the Aquaculture Department of the Southeast Asian Fisheries Development Center has successfully produced Haliotis asinina seeds in the hatchery. Aside from utilizing these seeds in aquaculture, they are also being considered for future stock enhancement endeavors of the department. This study aimed to evaluate post release behavior, recapture and growth rates of hatchery-reared abalone juveniles released in the Sagay Marine Reserve. From the two release trials conducted, results showed that abalone of shell length >3.0 cm had lower mortality during onsite acclimation and utilized transport modules as temporary shelter for a shorter period after release. Both wild and hatchery-reared abalone preferred dead branching corals with encrusting algae as their habitat. Recapture rates were comparable between the wild (7.97%) and hatchery-reared (HR2) abalone (6.47%). Monthly growth rates were almost the same between wild (0.25 cm, 4.0 g), hatchery-reared (HR1: 0.27 cm, 4.6 g; HR2: 0.35 cm, 3.8 g) abalone. Moreover, hatchery-reared abalone were recaptured up to 513 days post-release, indicating viability of released stocks in the wild. Results of releases revealed that hatchery-reared abalone can grow and survive with their wild conspecifics.
    • Article

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

      MJHL Lebata & JH Primavera - Journal of Shellfish Research, 2001 - National Shellfisheries Association
      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.
    • Article

      Growth and survival of hatchery-bred giant clams (Tridacna gigas) in an ocean nursery in Sagay Marine Reserve, Philippines 

      MJHL Lebata-Ramos, K Okuzawa, RJ Maliao, JBR Abrogueña, MDN Dimzon, EFC Doyola-Solis & TU Dacles - Aquaculture International, 2010 - European Aquaculture Society
      To restore the diminishing population of the giant clam Tridacna gigas in Sagay Marine Reserve (SMR), Negros Occidental, central Philippines, two size classes [8- and 10-cm shell length (SL)] of hatchery-bred T. gigas were reared in an adjacent ocean nursery for restocking to Carbin Reef later upon reaching grow-out size of ≥20 cm SL. Growth rates did not significantly differ for both sizes and were on average 0.67 cm month−1. However, survival after 382 days of rearing T. gigas was significantly higher in the 10-cm SL clams than the 8-cm SL clams (96 and 83%, respectively). For future restocking projects, the use of 8-cm SL clams is recommended because the lower survival of this size class is compensated by its cheaper price. While rearing the clams to attain grow-out size, the population of wild clams (Family Tridacnidae) in Carbin Reef was assessed using ten 50 × 2-m belt transects. Four species of tridacnid clams have been recorded: Hippopus hippopus, Tridacna crocea, T. maxima>, and T. squamosa. T. crocea comprised 12.5–93.9% of all the clams observed in all ten transects. There was a significant difference in clam density between species (ANOVA, F = 6.94, P < 0.001), with T. crocea having the highest density. Living T. gigas were absent, but presence of dead shells was indicative of its presence in the reef in the past. It can be expected that the release of hatchery-bred T. gigas juveniles in Carbin Reef could provide future breeders that will repopulate this reef and the adjacent reef communities.
    • Book

      Handbook of mangroves in the Philippines - Panay 

      JH Primavera, RB Sadaba, MJHL Lebata & JP Altamirano - 2004 - Aquaculture Department, Southeast Asian Fisheries Development Center
      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.
    • Article

      Identifying mangrove areas for fisheries enhancement; population assessment in a patchy habitat 

      MJH Lebata, ME Walton, JB Biñas, JH Primavera & L Le Vay - Aquatic Conservation: Marine and Freshwater Ecosystems, 2012 - Wiley
      1. Small-scale fisheries are an important element of the ecosystem goods and services that mangrove habitats provide, especially to poorer coastal communities that rely most on natural resources, and have similar values to payments for ecosystem services (PES) under carbon-trading schemes.
      2. In advance of fishery-enhancement trials for the mud crab Scylla olivacea, a mark–recapture study was conducted to estimate population size and turnover in 50 ha of isolated mangrove on Panay Island, Philippines. A total of 811 crabs were released in six sessions with an overall recapture rate of 41.5 ± 3.6%. Population size ranged from 607–1637 individuals.
      3. There was a high degree of site-fidelity, with 45.5% of recaptures in the same sampling areas as releases. Total mortality was 0.79 month-1, with fishing mortality accounting for 95% of overall mortality.
      4. Von Bertalanffy and Gompertz growth models yielded estimates for L (carapace width) of 117.3 ± 14.7 and 110.6 ± 2.1 mm and for k of 2.16 ± 0.74 and 3.25 ± 0.81, respectively. Crab densities of 12–33 individuals ha-1 in the study area were lower than in other mangrove systems owing to intermittent recruitment, while growth rates indicated no limitation in terms of food supply.
      5. The study demonstrates that in specific mangrove habitats that are below carrying capacity, there is potential for fisheries enhancement to sustain or increase direct economic benefits from mangrove ecosystems and hence promote community engagement in broader conservation and PES initiatives.
    • Article

      Mangroves and shrimp pond culture effluents in Aklan, Panay Is., central Philippines 

      JH Primavera, JP Altamirano, MJHL Lebata, AA delos Reyes Jr. & CL Pitogo - Bulletin of Marine Science, 2007 - University of Miami, Rosenstiel School of Marine and Atmospheric Science
      The capacity of a natural mangrove system in Ibajay, Aklan province, central Philippines to process shrimp pond culture effluents was assessed through analysis of mangrove community structure and 24-hr monitoring of water quality parameters (NH3-N, NO3-N, PO4-P, sulfide, and total suspended solids). Results from the latter showed decreased nutrient levels within 6 hrs after daytime draining of effluents into the mangrove stand, but only nitrate reduction was statistically significant. Based on nitrate loss, volume of water drained, mangrove area, and shrimp farming data (e.g., N loss from ponds, feed composition, feeding rate), calculations show that 1.8–5.4 ha of mangroves are required to remove nitrate wastes from 1 ha of shrimp pond. N uptake by the mangrove macroflora was supported by data showing longer nipa palm leaflets and faster mangrove seedling growth in the experimental mangrove receiving effluents compared to a control mangrove, but not from mangrove biomass measurements. These results have significant implications for the Philippine brackishwater pond culture industry to conserve or rehabilitate mangroves as potential pond biofilters, to implement legally mandated 20- and 50-m greenbelts, and to reverse the national 0.5 ha mangrove: 1.0 ha pond ratio.
    • Article

      Morphometric relationship of length and weight of giant tiger prawn Penaeus monodon according to life stage, sex and source. 

      JH Primavera, FD Parado-Estepa & JL Lebata - Aquaculture, 1998 - Elsevier
      Regression analysis was performed on length–weight and length–length measurements of Penaeus monodon (n=3270 individuals) including carapace length, body length, total length and body (wet) weight of different life stages (nursery, growout and broodstock), sexes (female and male) and sources (pond and wild). Regression lines differed among the life stages and between the sexes and sources at the broodstock stage. Nursery and growout P. monodon showed a greater weight gain per unit length than broodstock. With bigger females, size dimorphism appeared only at the broodstock stage; males and females showed similar sizes in nursery and growout. Equations (including a, b and r) for interconversions of length and weight are reported for the different stages, sources and sexes.