Culture of the Calanoid Copepod, Acartia erythraea and Cyclopoid Copepod, Oithona brevicornis with various Microalgal diets

Two experiments were conducted to develop Acartia erythraea and Oithona brevicornis cultures: The performance of five microalgal diets to produce nauplii, copepodites and adults of A. erythraea; and the performance of the same diets to produce nauplii, copepodites and adults of O. brevicornis. The five different microalgal diets were Isochrysis galbana (IG), Chaetoceros affinis (CA), Chlorella marina (CM), Nannochloropsis oculata (NO) and mixed algae (mixture of IG, CA, CM and NO at an equal abundance to provide the exact cell density). The results indicated that the abundance of both A. erythraea and O. brevicornis was higher in tanks supplied with IG and mixed algae than the tanks supplied with CA, CM and NO. IG and mixed algal diets were statistically similar on the mean abundance for both A. erythraea and O. brevicornis. The maximum production of A. erythraea nauplii was observed on day 12 of culture period and the nauplii production decreased from day 13 onwards. The mean abundance of A. erythraea copepodites and adults increased along with time up to the end of the culture period. In the case of O. brevicornis nauplii, the maximum abundance was observed on day 9 day of culture period and the nauplii production decreased from day 10 onwards. The mean abundance of O. brevicornis copepodites and adults increased gradually from the beginning to the end of the culture period. Under the experimental conditions of this study, both IG and mixed algal diets can be recommended for the best growth performance of A. erythraea and O. brevicornis

Evaluation of copepods as live feed for the larval Asian seabass (Lates calcarifer)

Seabass (Lates calcarifer) is one of the most important economically food fish in many Asian countries. However, total capture production of this fish is decreasing day by day in Malaysia due to decreasing wild stock, which puts increasing demand on the aquaculture of this fish. Many studies have been done on the aquaculture of Asian seabass. However, larval rearing techniques, including suitable nursery feeds is not yet standardized, which is crucial for better survival and growth of Asian seabass larvae. Live–feed is the essential for almost all fishes at least during the initial stages of their life cycle. It is already known that Asian seabass larvae prefer rotifer in age between 1 and 5 days, rotifer and Artemia nauplii in age between 6 to 10 days and only Artemia nauplii in age between 11 to 14 days. However, there is no reliable information on suitable live feed for the growth of Asian seabass larvae when age after 14 days. Based on this issue, a study was conducted to know the effects of feeding Artemia nauplii, and adult and nauplii of two copepods (Acartia erythraea and Oithona brevicornis) on growth and survival of 14, 20 and 25 days old Asian seabass larvae. Acartia erythraea and O. brevicornis were chosen in this study as they are nutritionally rich, easy to culture, high rate of reproduction, salinity tolerance and available in tropical waters. A 21-day experiment was conducted in 45 fibreglass tanks. The size of each tank was 70 cm × 50 cm × 30 cm holding approximately 100 L of seawater. A factorial design was used, the factors being fish larval age (3 levels: 14, 20 and 25 days old Asian seabass larvae) and live feed (5 levels: nauplii of A. erythraea, adult of A. erythraea, nauplii of O. brevicornis, adult of O. brevicornis and nauplii of Artemia). The combinations of the two factors resulted in a total of 15 treatments, all of which were performed in triplicate. A total of 1000 fish larvae (10 larvae/L) were stocked in each tanks. All fish larvae were collected from a seabass hatchery while both copepods were cultured in the laboratory. All larvae were fed three times a day, at approximately 06:30 h, 13:00 h and 19:30 h. The results indicated that seabass larvae grew better (higher specific growth rate, final length and final weight) in tanks supplied with copepods than Artemia nauplii. The effects were more pronounced in the case of 25 days old larvae than in the case of 20 days old larvae, followed by 14 days old larvae. Fatty acid analysis analysis of L. calcarifer larvae showed that total n-3 fatty acids were higher in larvae fed with copepods diet than those of feeding with Artemia nauplii diet. Therefore, besides higher growth rates, the quality of seabass seeds can be improved if A. erythraea or/and O.brevicornis is/are used as live feed. This experiment suggests that the copepods can be used as a suitable live feed for larval rearing of highly valued L. calcarifer larvae

Relative growth of harpiosquilla raphidea (Fabricius, 1798) (crustacea: stomatopoda) male and female populations

Morphometric analysis was carried out to find out changes in the growth pattern of male and female stomatopod, Harpiosquilla raphidea. Six morphometric relationships were examined on 105 males and 105 females, ranging in size from 103 to 207 mm and from 104 to 222 mm in total length, respectively. In both the sexes, the relative growth of carapace length, propodus length of raptorial claw and total weight in relation to total length was found positively allometric. Telson width in both the sexes and abdomen width in males showed slightly negative allometry, while the abdomen width of females showed slightly positive allometry, indicating some variation in the growth between sexes which could be attributed to the energy requirement for maturation in females. The propodus of females was also found to be bigger than that of males. It is quite interesting as males only have larger chela in other crustaceans. It has a functional significance in that it is of immense help at the time of intense feeding during maturation of oocytes which requires higher energy

Effects of water temperature on survival, growth, digestive enzyme activities, and body composition of the leopard coral grouper Plectropomus leopardus

The effects of water temperature (15, 20, 25,30, and 35 °C) on survival, growth performance, digestive enzyme activities, and body composition of Plectropomus leopardus were studied for a period of 6 weeks. One hundred eighty fish with initial body weights of 26.5 ± 1.5 g were randomly arranged into 15 glass aquaria in equal numbers in five recirculating systems to form five groups in triplicate. The results showed that survival of P. leopardus at 35 °C was significantly greater (P < 0.05) than survival at 15 °C. No death was recorded at 20, 25, and 30 °C. Among all treatment groups, the significantly highest average individual harvesting weight, weight gain, feed ingestion rate and protease enzyme activity of P. leopardus were observed in 30 °C group. Similar results were also observed in protein and fat content in this species. Based on the present findings, a culture temperature of 30 °C can be considered to be the optimum temperature for the aquaculture of juvenile P. leopardus. However, more research is still needed to optimize the nutrition and photoperiod of P. leopardus culture

Seasonal variations of plankton in Kodiakkarai and Arukattuthurai on the Vedharanyam coast, South India

Composition and community structure of phyto-, microzoo- and mesozoo-plankton off Kodiakkarai and Arukattuthurai on the Vedharanyam coast, South India were investigated over one year (September 2006 to August 2007). One hundred and sixteen phytoplankton species were observed under different classes: Bacillariophyceae (90 species); Dinophyceae (20); Cyanophyceae (5) and Chrysophyceae (1) were recorded. Phytoplankton abundance varied from 9.9 to 78.1 cells mL−1, with peak Shannon– Weaver diversity, H’ of 6.18 during summer (April–June) when there was a stable hydrographical condition. A total of 37 microzooplankton species were recorded (Tintinnids 17, Rotifera 2, Appendicularia 2 and Larval forms 16). Microzooplankton abundance ranged between 3.3 and 27.7 ind. mL−1, with peak diversity of 4.56 during summer. Fifty-five species of mesozooplankton including 42 copepods formed the dominant group. The mesozooplankton abundance ranged between 5.4 and 14.5 and between 11.4 and 52 ind. mL−1 at stations 1 and 2, respectively. Arukattuthurai coastal waters were very rich and mesozooplankton diversity was high (5.22) at station 2 (Arukattutharai), although slightly lower (4.58) at station 1 (Kodiakkarai). The occurrence of most of the phyto- , microzoo- and mesozoo-plankton species in Kodiakkarai and Arukattuthurai coastal waters were distinctly seasonal. Therefore, variations of the micro- and mesozoo-plankton species were subjected to seasonal fluctuations in environmental parameters which were strongly influenced seasonally, including by freshwater influence. The highest values of mesozooplankton abundance and species diversity were found during summer and were positively correlated with salinity

Culture of the calanoid copepod, Acartia erythraea and cyclopoid copepod, Oithona brevicornis with various microalgal diets = Kultur kopepod kalanoid, Acartia erythraea dan kopepod siklopoid, Oithona brevicornis dengan pelbagai diet mikroalga

Two experiments were conducted to develop Acartia erythraea and Oithona brevicornis cultures: The performance of five microalgal diets to produce nauplii, copepodites and adults of A. erythraea; and the performance of the same diets to produce nauplii, copepodites and adults of O. brevicornis. The five different microalgal diets were Isochrysis galbana (IG), Chaetoceros affinis (CA), Chlorella marina (CM), Nannochloropsis oculata (NO) and mixed algae (mixture of IG, CA, CM and NO at an equal abundance to provide the exact cell density). The results indicated that the abundance of both A. erythraea and O. brevicornis was higher in tanks supplied with IG and mixed algae than the tanks supplied with CA, CM and NO. IG and mixed algal diets were statistically similar on the mean abundance for both A. erythraea and O. brevicornis. The maximum production of A. erythraea nauplii was observed on day 12 of culture period and the nauplii production decreased from day 13 onwards. The mean abundance of A. erythraea copepodites and adults increased along with time up to the end of the culture period. In the case of O. brevicornis nauplii, the maximum abundance was observed on day 9 day of culture period and the nauplii production decreased from day 10 onwards. The mean abundance of O. brevicornis copepodites and adults increased gradually from the beginning to the end of the culture period. Under the experimental conditions of this study, both IG and mixed algal diets can be recommended for the best growth performance of A. erythraea and O. brevicornis. Dua eksperimen telah dijalankan untuk menghasilkan kultur Acartia erythraea dan Oithona brevicornis: Prestasi lima diet mikroalga untuk menghasilkan nauplii, kopepodites dan dewasa A. erythraea; dan prestasi diet yang sama untuk menghasilkan nauplii, kopepodites dan dewasa O. brevicornis. Lima diet mikroalga tersebut adalah Isochrysis galbana (IG), Chaetoceros affinis (CA), Chlorella marina (CM), Nannochloropsis oculata (NO) dan alga campuran (campuran IG, CA, CM dan NO pada jumlah yang sama banyak untuk mendapatkan kepadatan sel yang tepat). Keputusan menunjukkan bahawa bilangan kedua-dua A. erythraea dan O. brevicornis adalah lebih tinggi di dalam tangki yang dibekalkan dengan IG dan alga campuran daripada tangki yang dibekalkan dengan CA, CM dan NO. Diet IG dan alga campuran juga menunjukkan statistik yang sama dalam purata kelimpahan kedua-dua A. erythraea dan O. brevicornis. Bilangan maksimum naupli A. erythraea diperhatikan pada hari ke-12 tempoh kultur dan pengeluaran nauplii menurun bermula dari hari ke-13 dan seterusnya. Purata kopepodites dan A. erythraea dewasa meningkat sejajar dengan masa sehingga akhir tempoh kultur. Dalam kes naupli O. brevicornis, kepadatan maksimum diperhatikan pada hari ke-9 tempoh kultur dan pengeluaran nauplii menurun pada hari ke-10 dan seterusnya. Purata kopepodites dan O. brevicornis dewasa meningkat secara beransur-ansur dari awal hingga akhir eksperimen. Di bawah keadaan eksperimen dalam kajian ini, kedua-dua diet IG dan alga campuran boleh disyorkan untuk prestasi pertumbuhan terbaik bagi A. erythraea dan O. brevicornis

Seasonal variations in the structure of copepod assemblages in tropical marine and estuarine waters, Coleroon, South-East India

A twelve-month investigation was undertaken on how copepod community structure varied in relation to environmental factors in the Coleroon estuary, south-east India. Sampling was monthly, from Station 1 in the sea to Station 4 in the Vettar backwaters. Canonical correspondence analysis (CCA) was applied to elucidate the environmental factors affecting the copepod community. A total of 104 copepod species in 38 genera and 26 families were recorded, with the Calanoids, Acartia erythraea and Oithona brevicornis being the most dominant. At all four stations, both these species loaded near the intercept of CCA axes 1 and 2, perhaps reflecting that they were autochthonous. Most species occurred in distinct seasonal patterns. Abundances ranged from 13 × 103 to 215 × 103 (ind. m-3). Coleroon waters showed high diversity (bits/ind.), from 5.29 at Station 3 to 4.97 at Station 4. Abundance correlated positively with temperature and salinity and negatively with rainfall, dissolved oxygen concentration (DO) and pH. Species diversity correlated strongly with abundance (P<0.01). Abundance and diversity were highest during the summer, and both correlated positively with salinity. Temperatures (air and water), salinity, pH and DO varied in the ranges 26–36oC,25–34.2oC, 9–38, 7.0–8.7 and 3.0–6.8 ml l-1, respectively. Nitrate, nitrite, phosphate and silicate (mM) varied in the ranges: 4.7–64.5, 0.4–14.1, 0.2–12.9 and 9.3–148, respectively

Community structure of microzooplankton in a tropical estuary (Uppanar) and a mangrove (Pichavaram) from the southeast coast of India

In the marine and estuarine waters of Cuddalore, the southeast coast of India microzooplankton have previously been sparingly investigated. Micro-zooplankton community structure (species composition, abundance, diversity, richness, evenness) of an estuary and mangroves of the Cuddalore and Pichavaram areas, southeast India were investigated in detail. Monthly samples were taken from April 2000 to March 2002, from four fixed stations. Micro-zooplankton taxon composition and abundance showed seasonal variations being highest in summer (45 to 50 ind./l in April to August 2000; 60 to 67.5 ind./l in April to June 2001) and lowest during the monsoon (6 to 16 ind./l in September to December 2000; 7 to 19 ind./l in October to December 2001). The total abundance of microzooplankton was in the range of 10.3-65.0 ind./l in Cuddalore areas (Stations 1 and 2) and 5.2 - 67.5 ind./l in Pichavaram mangroves (Stations 3 and 4). Over the study period, tintinnids dominated the microzooplankton community in terms of both abundance and species diversity. The remaining taxa included Radiolaria, Foraminifera, Rotifera, ciliates other than tintinnids, and metazoans. A total of 62 and 74 species of microzooplankton were recorded from Cuddalore and Pichavaram mangroves respectively. Canonical Correspondence Analysis (CCA) was applied to discriminate environmental factors associated with the microzooplankton community at the species level. The results of the study provide a basis for rational sustainable exploitation of Cuddalore waters and future research on its living resources. Furthermore, a comparison of results with studies from around the world showed a very strong, significant relationship between abundance and sampling methods underlining the need for standardized protocols

Effect of ingestion and waterborne routes under different shrimp densities on white spot syndrome virus susceptibility in three commercially important penaeid shrimps

A study was undertaken to evaluate some factors that are important for better management of the white spot syndrome virus (WSSV). We examined the likelihood of that the mud crab (Scylla serrata) is a potential carrier of WSSV in shrimp farms and then compared susceptibility of three shrimp species to WSSV, and finally tested the effects of shrimp stocking density and transmission routes on the intensity of WSSV infection under experimental conditions. Mud crabs were collected from the crab fattening unit of Pichavaram mangroves area, southeast coast of India. The infectivity test was conducted on Penaeus monodon, P. indicus, Litopenaeus vannamei under three different shrimp densities and two different routes of infection. Each treatment was executed in triplicate of 100 L tanks. The results showed that S. serrata is a carrier of WSSV. Among three species of shrimps, P. indicus was most susceptible and L. vannamei was most resistant in term of cumulative mortality. Ingestion route was more effective than waterborne route on WSSV outbreaks. Cumulative mortality of shrimps due to WSSV infection increased with increasing shrimp density. The result of this study is important to improve management especially to minimize the WSSV infection in the shrimp farms

Effect of cholymbi on growth, proximate composition, and digestive enzyme activity of fingerlings of Long whiskered catfish, Mystus gulio (actinopterygii: siluriformes: bagridae)

Background. Long whiskered catfish, Mystus gulio (Hamilton, 1822), enjoys a high consumer preference and market demand in many Asian countries including India. However, the growth of this fish is very slow under normal aquaculture conditions. The non-hormonal growth promoter—cholymbi—which contains minerals and the essential amino acids lysine and methionine, is widely used in livestock and poultry as a feed additive to improve growth and survival. Supplementing feed with cholymbi may increase the growth and survival of Mystus gulio. Materials and methods. A feeding trial was conducted to determine the effect of dietary cholymbi supplementation on growth, survival, and feed conversion ratio of long whiskered catfish fingerlings. Four isoproteic diets (crude protein 37%) were formulated to incorporate cholymbi at 0%, 0.25%, 0.50%, and 0.75% diet. The diets were fed to triplicate groups of fish twice daily to supply 5% of the total body weight per day for 120 days. Water quality parameters were maintained within the range suitable for catfish growth. Results. Weight gain (WG), protein efficiency ratio (PER) and feed conversion ratio (FCR) were all affected by diet (P < 0.01, 0.001, and 0.001, respectively). The group fed the 0.50% cholymbi diet had the highest WG and PER and the lowest FCR, although not significantly different from the group fed the 0.25% cholymbi diet. There was no significant difference (P > 0.05) in carcass proximate composition of catfish fed diets containing these different levels of cholymbi. Gut protease, amylase, and lipase activities were stimulated by dietary inclusion of cholymbi at all levels compared to control. Conclusion. As cholymbi is a newly introduced dietary supplement for fish, more research is needed to optimize its supplementation to improve growth, PER, FCR, and survival of long whiskered catfish. Until then, a diet with 0.50% cholymbi can be recommended to improve the aquaculture production of this species