Maximum Daily Growth Rate Research Articles

Age, Growth and Population Structure Analyses of the Purpleback Flying Squid Sthenoteuthis oualaniensis in the Northwest Indian Ocean by Beak Microstructure

To explore the feasibility of using beak microstructure information to estimate the age of Sthenoteuthis oualaniensis, the microstructures of the upper beaks of individual squid were applied in this work to analyze the ages and growth patterns of squid caught from February–May 2019 and from October–December 2020 in the northwest Indian Ocean. The results indicated that the squid samples in the two years were no older than 9 months, and the samples in 2019 were autumn population and 2020 were spring population. The linear growth model of the autumn population (2019) was the best model for describing the relationship between age and ML, while the power model of the spring population (2020) was the best for describing the relationship between age and ML. The maximum instantaneous growth rate (IGR) and absolute daily growth rate (AGR) values of the spring population were 0.24%/d and 1.09 mm/d, respectively, occurring in squid between 200 and 220 days of age. The maximum IGR and AGR values of the autumn population were 0.69%/d and 1.73 mm/d, respectively, occurring in squid between 200 and 240 days of age. The period from 141–260 days (5–8 months) was considered to correspond to the subadult stage in the whole life history of S. oualaniensis in the Northwest Indian Ocean. The beak microstructure information can be effectively applied to estimate the age of S. oualaniensis individuals.

Improvement of breeding methods of predatory mites Neoseiulus cucumeris and Transeius montdorensis for biological plant protection

The possibility of breeding of phytoseiid predatory mites Neoseiulus cucumeris and Transeius montdorensis using hardwood sawdust as a substrate and frozen dried fruit mite (Carpoglyphus lactis) as feed was studied. The number of larvae produced by N. cucumeris was 31.5 % lower on frozen feed in sawdust than in the control, while in T. montdorensis it was lower by 47.7 %. The number of individuals surviving to adulthood compared to the control was lower by 28.6 % and 42.9 %, respectively. The maximum daily growth rate of the population was reduced relatively to the control by 3.7 individuals in N. cucumeris, and by 4.5 in T. montdorensis –. On frozen feed in bran, N. cucumeris produced 20.5 % fewer larvae than in the control, T. montdorensis – 35.1 % fewer larvae. The number of individuals surviving to adulthood was reduced by 18.3 % and 35.3 %, respectively, compared to the control. The maximum daily population growth rate was 1.7 individuals lower than in the control in N. cucumeris, and – 3.9 individuals lower in T. montdorensis. On live feed in sawdust, larval production was similar to the control (lower by 1.1 % in N. cucumeris and 14.2 % in T. montdorensis). The number of individuals was reduced relatively to the control by 1.7 % and 14.8 %, respectively. The maximum daily population growth rate in N. cucumeris is slightly lower (by 0.7 individuals) than in the control, and in T. montdorensis it even exceeded the control by 0.6 individuals per day. Our results showed the possibility of using sawdust as a cheaper substrate for breeding of both species of predatory mites and poor performance of the frozen feed compared to the live one.

Beak Microstructure Estimates of the Age, Growth, and Population Structure of Purpleback Flying Squid (Sthenoteuthis oualaniensis) in the Xisha Islands Waters of the South China Sea

This study aimed to explore the feasibility of using an upper beak microstructure to estimate the age of purpleback flying squid (Sthenoteuthis oualaniensis). From these microstructures, the age and growth of squid caught from January to March and May to August in 2018, 2019, and 2020 in the waters surrounding the Xisha Islands in the South China Sea were determined. We found three typical growth zones (the hood region, crest region, and axis), abnormal increments (checks), and erosion in the beak examination. The average dorsal mantle length (ML) of males and females was 112.13 (±15.23 mm) and 119.67 mm (±24.50 mm), respectively, and no squid were older than 10 months. The peak hatching dates, according to back calculations, were from October to January of the next year. All sampled squid belonged to the autumn/winter cohort. Significant sex differences were found in the relationship between ML and age in squid with similar growth patterns. Exponential models best described the relationships of ML with age and body weight (BW) for both sexes. However, a linear model best described the relationship between age and upper rostrum length (URL). The maximum absolute daily growth rates (AGR) of BW were reached during days 240–270 for both sexes. The maximum AGRs in ML were reached during days 180–210 and 240–270 for males and females, respectively. The period of 120–150 days (4–5 months) was considered the sub-adult stage of S. oualaniensis in the Xisha Islands waters of the South China Sea. This study confirmed that the beak microstructure provides good age estimates for purpleback flying squid (S. oualaniensis).

Simplified methods for on-farm prediction of yield potential of grazed lucerne crops in New Zealand

ABSTRACT Analyses of New Zealand farm systems require estimates of herbage yield and quality. These are available for perennial ryegrass and white clover pastures but not for other common pasture species. We used five lucerne datasets to derive functional relationships between growth rate and temperature. This required three functions to account for partitioning in lucerne between spring and autumn and differences between seedling and regrowth crops. The maximum mean daily growth rate of 206 ± 5.95 kg DM/ha/d occurred with full canopy cover at mean air temperatures between 15°C and 22°C. This represents the upper end of the temperature range available. The relationship was summarised into a matrix that could be incorporated into existing forage forecasters for farm system analyses. Alternatively, a simplified model assessed growth rate in relation to thermal time. This showed after 140°Cd accumulated from 1 July, lucerne initiated spring growth at 11.9 kg DM/ha/°Cd until mid-January and then decreased to 6.7 kg DM/ha/°Cd from mid-January to 30 June for fully irrigated crops. An exponential heightchron relationship was also calculated to estimate crop height based on the thermal time required per mm as photoperiod changed. This relationship allows lucerne quality to be predicted from the leaf:stem ratio.

Analysis of Air Quality Changes and Influencing Factors in Changchun during the COVID-19 Pandemic in 2020

To study the air quality changes during the Corona Virus Disease 2019 (COVID-19) lockdown in Changchun, we analyzed the changes in pollution of six major pollutants (PM2.5, PM10, SO2, NO2, O3, CO) and correlated them with meteorological parameters, using meteorological data and pollutants concentration data. Regional transport pathways and potential source areas of pollutants were analyzed using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and Potential Source Contribution Function (PSCF). The results showed that the concentrations of PM2.5, PM10, SO2, NO2, CO were 30.5%–53.8% lower in the Level I period and 49.4%–65.0% lower in the Level II period than in the pre-lockdown period, respectively. Conversely, O3 increased 59.6% and 58.1% during Level I and Level II, respectively, compared to the pre-lockdown period. During the 55-day lockdown, daily average concentrations of each pollutant were lower than in previous years on 36-55 days, while O3 was higher on 35 days. The pollutants that decreased in concentration during the lockdown also showed an increase during the Level III period (up to 188.5%). The maximum daily growth rate of PM2.5 during the lockdown period in 2020 was 16.0%, which was higher than this value in the same period of previous years (21.8%, 21.4%, 17.4%). This shows that the change trend of pollutants during the lockdown period is smoother than in previous years. Temperature and O3 were positively correlated before the lockdown and during Level I and weakly negatively correlated during Level II and Level III. Despite the prevalence of northwest winds in winter, a high percentage of trajectories from other directions (up to 36.8%) was observed during the lockdown. Simultaneously, the lockdown reduced the potential source area for PM2.5 (WPSCF ≥ 0.000007), but rebounded after the lockdown was lifted. In conclusion, the lockdown only temporarily reduced the air pollution in Changchun.

Short note: Preliminary observations on the propagule production of Sargassum polycystum C. Agardh from stoloniferous branches

Sargassum polycystum has a unique morphology, i.e. stoloniferous branches that arise from primary axes. The regeneration ability of these stoloniferous branches as vegetative propagules was investigated to optimize the growth parameters. Pieces of stoloniferous branch (2–3 cm) were subject to a range of salinities (25–50 psu), photoperiods (24,0, 8,16, 10,14, 12,12, 14:10, 16:8 and 0:24 h L:D), irradiance (5, 25 and, 45 μmol photons m−2 s−1) and pH (7, 7.5, 8, 8.5 and 9) for a period of 35 days. The maximum daily growth rate (DGR) was observed under the conditions of: 35 psu salinity (1.18 ± 0.35% day−1), 16:8 L:D photoperiod (0.94 ± 0.08% day−1), 45 μmol photons m−1 s−1 (1.13 ± 0.28% day−1), and pH 7.5 (1.14 ± 0.12% day−1). The vegetative propagules regenerated from stoloniferous branches were found to produce primary laterals (branches) and phyllodes (leaves) which, developed into new thalli, but without a holdfast.

Scaling the production of Monostroma sp. by optimizing culture conditions

Laboratory culture experiments were performed to optimize conditions for scaled-up production of Monostroma sp. The effects of growth determining factors like salinity (15–45 psu), photoperiod (8:16–16:8 L/D), light intensity (2–60 μmol photons m−2 s−1), and temperature (15–35 °C) on the growth of Monostroma sp. were assessed. Culture results indicated high tolerance capacity of Monostroma sp. to all levels in salinity, photoperiod, light intensity and temperature tested. ANOVA results confirmed significant impact of salinity, photoperiod, light intensity and temperature on growth rate (p < 0.05). The maximum growth rate was observed in the range of 5.73 to 14.41% day−1 which obtained in 35 psu salinity, 25 °C temperature, 14:10 (L/D) photoperiod, 60 μmol photons m−2 s−1 light intensity level and 1/4 MP1 medium. The modified 1/4MP1 medium was found to be suitable for enhanced growth of Monostroma sp. Outdoor tank culture with 1/4 MP1 medium showed maximum daily growth rate (14.38 ± 0.32% day−1).

Hatching Time and Early Growth of Diplodus sargus sargus Inhabiting a Coastal Area of Gökçeada Island, Turkey

Daily growth increments in sagittal otoliths were used to estimate the age and growth of young of the year (YOY) white seabream, Diplodus sargus sargus collected between June 2013 and June 2014 at 6 different locations in the shallow waters (<20 m) off Gokceada, Turkey. Estimated ages from otolith daily growth increments (DGI) were found 42–238 days old. The mean daily growth rate of YOY D. sargus sargus was estimated as 0.046 cm/day. ANCOVA indicated that there was significant difference in daily growth rates between the locations (F = 22.92, df = 5, P < 0.001). The maximum daily growth rate of 0.055 cm/day was found in the location 2, while the minimum value of 0.037 cm/day was observed in the location 4. Hatching time was determined by subtracting the daily age of the fish from the sampling date and then hatch date frequency distributions were determined to occur from January through June, and 2 main hatching peaks were observed from the different locations. Linear relationships between otolith morphology (otolith length; OL, width; OW and radius; OR) and fish length (TL) were obtained.

Appropriate nitrogen application enhances saponin synthesis and growth mediated by optimizing root nutrient uptake ability

BackgroundCultivation of medicinal crops, which synthesize hundreds of substances for curative functions, was focused on the synthesis of secondary metabolites rather than biomass accumulation. Nutrition is an important restrict factor for plant growth and secondary metabolites, but little attention has been given to the plasticity of nutrient uptake and secondary metabolites synthesis response to soil nitrogen (N) change. MethodsTwo year-field experiments of Sanqi (Panax notoginseng), which can synthesize a high level of saponin in cells, were conducted to study the effects of N application on the temporal dynamics of biomass, nutrient absorption, root architecture and the relationships between these parameters and saponin synthesis. ResultsIncreasing N fertilizer rates could improve the dry matter yields and nutrient absorption ability through increasing the maximum daily growth (or nutrient uptake) rate. Under suitable N level (225 kg/ha N), Sanqi restricted the root length and surface and enhanced the root diameter and N uptake rate per root length (NURI) to promote nutrient absorption, but the opposite status of Sanqi root architecture and NURI was found when soil N was deficient. Furthermore, increasing N rates could promote the accumulation of saponin in roots through improving the NURI, which showed a significant positive relationship with the content of saponin in the taproots. ConclusionAppropriate N fertilizer rates could optimize both root architecture and nutrient uptake efficiency, then promote both the accumulation of dry matter and the synthesis of saponins.

Feasibility study of Ulva sp. (Chlorophyta) intensive cultivation in a coastal area of the Eastern Mediterranean Sea

AbstractIncreasing biomass production yields is a critical challenge for macroalgae biorefineries. The continuous tumbling and mixing of free‐floating algae through water or airflow has been shown to increase the productivity of algae in land‐based cultivation systems. This approach has not been tested thoroughly in offshore cultivation. We report, here, a field feasibility study on the increase in green macroalga Ulva sp. growth rates in offshore cages, achieved by the combined effect of tumbling and mixing of the algae using influxes of water and air. The experimental system was tested in a shallow coastal area in central Israel, in the eastern Mediterranean Sea. A maximum daily growth rate of 19.2%, areal productivity of 33.72 g dry weight (DW) day−1 m−2, and volumetric yields of 37.78 g DW day−1 m−3, together with 38.47 ± 0.01% ash and 5.28% protein content on a dry matter basis were achieved in the cages with intensified cultivation in the first week of May 2017. Our study shows that cultivation with tumbling and mixing of biomass with air, and water exchange with the environment is a feasible method to increase Ulva sp. biomass productivity offshore. © 2019 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Effect of stocking density on the growth and survival of Anomalocardia brasiliana (Gmelin, 1791) (Bivalvia: Veneridae) post-larvae

ABSTRACT: Anomalocardia brasiliana post-larvae were cultured for 28 days to evaluate the effect of stocking density on their growth and survival rate. Three stocking densities were tested 40, 80 and 160 post-larvae cm-2, in experimental units (2-L) with static cultivation system and total water renewal at each 48 hours. The experimental design was completely randomized with three treatments and three repetitions each. Stocking density of 40 post-larvae cm-2 reached 1 mm length within 24 days, while only 18% of the post-larvae at density of 80 post-larvae cm-2 reached 1 mm length in the same time. The density of 40 post-larvae cm-2 had the highest specific growth rate, 4.98±0.08% day-1. The survival rates of post-larvae at lower densities were significantly higher (53.24±4.60% and 52.95±3.32%, on 40 and 80 post-larvae cm-2, respectively) compared to higher stocking density (31.54±0.70%). In the cultivation of A. brasiliana post-larvae, stocking density must be managed during growth. The density of 160 post-larvae cm-2 can only be used until the post-larvae reach 600μm in length, then they should be at 40 post-larvae cm-2 density to keep the maximum daily growth rate.

Temporal Differentiation of Crop Growth as One of the Drivers of Intercropping Yield Advantage

Intercropping studies usually focus on yield advantage and interspecific interactions but few quantify temporal niche differentiation and its relationship with intercropping yield advantage. A field experiment conducted in northwest China in 2013 and 2014 examined four intercropping systems (oilseed rape/maize, oilseed rape/soybean, potato/maize, and soybean/potato) and the corresponding monocultures. Total dry matter data collected every 20 d after maize emergence were fitted to logistic models to investigate the temporal dynamics of crop growth and interspecific interactions. All four intercropping systems showed significant yield advantages. Temporal niche complementarity between intercropped species was due to differences in sowing and harvesting dates or the time taken to reach maximum daily growth rate or both. Interspecific interactions between intercropped species amplified temporal niche differentiation as indicated by postponement of the time taken to reach maximum daily growth rate of late-maturing crops (i.e. 21 to 41 days in maize associated with oilseed rape or potato). Growth trajectories of intercropped maize or soybean recovered after the oilseed rape harvest to the same values as in their monoculture on a per plant basis. Amplified niche differentiation between crop species depends on the identity of neighboring species whose relative growth rate is crucial in determining the differentiation.

A heat wave during leaf expansion severely reduces productivity and modifies seasonal growth patterns in a northern hardwood forest.

A useful approach to monitor tree response to climate change and environmental extremes is the recording of long-term time series of stem radial variations obtained with precision dendrometers. Here, we study the impact of environmental stress on seasonal growth dynamics and productivity of yellow birch (Betula alleghaniensis Britton) and sugar maple (Acer saccharum Marsh.) in the Great Lakes, St Lawrence forest region of Ontario. Specifically, we research the effects of a spring heat wave in 2010, and a summer drought in 2012 that occurred during the 2005–14 study period. We evaluated both growth phenology (onset, cessation, duration of radial growth, time of maximum daily growth rate) and productivity (monthly and seasonal average growth rates, maximum daily growth rate, tree-ring width) and tested for differences and interactions among species and years. Productivity of sugar maple was drastically compromised by a 3-day spring heat wave in 2010 as indicated by low growth rates, very early growth cessation and a lagged growth onset in the following year. Sugar maple also responded more sensitively than yellow birch to a prolonged drought period in July 2012, but final tree-ring width was not significantly reduced due to positive responses to above-average temperatures in the preceding spring. We conclude that sugar maple, a species that currently dominates northern hardwood forests, is vulnerable to heat wave disturbances during leaf expansion, which might occur more frequently under anticipated climate change.

Age, growth and population structure of jumbo flying squid Dosidicus gigas off the Peruvian Exclusive Economic Zone based on beak microstructure

The beak is a hard structure of cephalopods with relatively constant shape, which records a lot of biological and ecological information. Based on samples collected by Chinese squid jigging vessels off the Peruvian Exclusive Economic Zone from July to October 2013, we explored the feasibility of age estimation and growth pattern with the upper beak of Dosidicus gigas. The internal rostral axis and longitudinal increments could be clearly identified on the upper beak rostrum sagittal sections of this species. Checks and abnormal structure were observed in some beaks. Ages estimated were from 123 to 298 days for females and from 106 to 274 days for males. Back-calculated hatching dates were from December 2012 to May 2013. All of the samples were from the austral summer/autumn spawning cohort. Hatching peak occurred between January and March. Growth in mantle length (ML) and body weight were best described by exponential functions and there were no significant differences between females and males. The maximum absolute daily growth rate and instantaneous growth rate of ML were 2.12 mm/day and 0.59/day, respectively. This study suggests that the upper beak could be used for estimating age, growth and population structure of D. gigas.

Comparative Study of Growth and Carrageenan Content of Kappaphycus alvarezii (Doty) Doty in Pen Culture and Raft Culture in Palk Bay Waters of Ramanthapuram District, Southeast Coast of India

The cultivation of Kappaphycus alvarezii, a kappa carrageenan yielding red seaweed has been going on in different locations of the world since 1970. This seaweed has been introduced under field cultivation in more than 20 tropical countries. Philippines and Indonesia contribute to 92% of the entire global harvest of 183,000 ton dry and the other countries include Malaysia, China and Salmon Islands. In India, this alga has been introduced in the second half of 1995 and the commercial cultivation has picked up from 2006. In order to evolve an economically feasible method for commercial cultivation, this study was done for a period of one year from April 2010 to March 2011 in sub-tropical waters on Palk Bay side of Bay of Bengal of Ramanthapuram (Umiyalpuram, Mandapam) district on southeast coast of India. The experiments were carried out by two methods, 1) PEN culture i.e; cultivation in monolines enclosed with net and 2) raft method with net bottom. The minimum crop yields of 241.10±9.52 and 228.90±14.89 kg FW raft-1 were obtained in May 2010 in PEN culture and raft respectively with respective maximum ones of 325.30±11.26 and 293.10±9.83 kg FW raft-1 in October 2010. Similarly the minimum daily growth rates (DGRs) of 3.09±0.09 and 2.97±0.09 % were found in May 2010 in PEN culture and raft culture respectively with respective maximum daily growth rates (DGRs) of 3.76±0.08 % and 3.52±0.07% in October 2010. Environmental parameters like seawater temperature, salinity, nitrate and phosphate were recorded and they were found to influence the growth of the seaweed. The maximum carrageenan (SRC) content of 36.76±0.74% and 34.09±0.97% of dry weight was found in August 2010 for PEN culture and raft culture respectively whereas the minimum ones of 31.92±1.28% in December 2010 in Pen culture and 30.04±0.12% in October 2010 in raft culture. The income with mean annual crop yields would be Rs. 18,257/- and Rs. 16,063/- per month/person in PEN culture and raft respectively during the loan period and with the respective ones of Rs. 19,257/- and Rs. 18,063/- per month/ person after the loan period (after three years). In view of this, PEN culture was recommended for commercial cultivation rather than raft one in the shallow waters and this was arrived at considering the infra cost, replacement of the infra, cultivation operation, carrageenan yield and net income. Keywords: Seaweed farming, Daily growth rate, Kappaphycus, Carrageenan, Crop yield

Performance of Red Seaweed (Kappaphycus sp.) Cultivated Using Tank Culture System

Little is known on the performance of seaweed cultivated in land-based facilities. The present study was conducted to determine the performance of Kappaphycus sp. cultivated in tank culture system with the effect of seaweed density, usage of Acadian Marine Plant Extract Powder (AMPEP), AMPEP fertilizer and the observation on the disease occurrence. Two red seaweed species (K. alvarezii variety Brown Tambalang, BT and K. striatum variety Green Flower, GF) were selected and mutually cultivated using hanging culture method. Three 40 days trials were conducted with different seaweed density (Trial 1:2.40, Trial 2:1.92 and Trial 3:0.96 g L−1). Besides, four treatments were performed in each trial: T1 (filtered seawater only), T2 (filtered seawater enriched with 13 mg L−1 AMPEP fertilizer), T3 (filtered seawater enriched with sands and corals and T4 (filtered seawater enriched with 13 mg L−1 AMPEP fertilizer, sands and corals). Based on the result, the maximum daily growth rate (2.00±0.03% day−1 for K. striatum and 1.46±0.06% day−1 for K. alvarezii) was recorded during Trial 3 with the lowest seaweed density using T4 treatment under natural culture parameters of light intensity, DO level, pH, temperature and salinity. In the present study, the performance of seaweed culture in tank was challenged by diseases such as “ice-ice� and seawater epiphyte infection that might cause bleached stems and weight loss to the seaweed. These findings are significant to provide a baseline data and facilitate the land-based seaweed farming in the future. © 2015 Academic Journals Inc.

Population dynamics of Aurelia sp.1 ephyrae and medusae in Jiaozhou Bay, China

The scyphozoan Aurelia aurita (Linnaeus) s. l., is a cosmopolitan species-complex which blooms seasonally in a variety of coastal and shelf sea environments around the world. We hypothesized that ephyrae of Aurelia sp.1 are released from the inner part of the Jiaozhou Bay, China when water temperature is below 15°C in late autumn and winter. The seasonal occurrence, growth, and variation of the scyphomedusa Aurelia sp.1 were investigated in Jiaozhou Bay from January 2011 to December 2011. Ephyrae occurred from May through June with a peak abundance of 2.38 ± 0.56 ind/m3 in May, while the temperature during this period ranged from 12 to 18°C. The distribution of ephyrae was mainly restricted to the coastal area of the bay, and the abundance was higher in the dock of the bay than at the other inner bay stations. Young medusae derived from ephyrae with a median diameter of 9.74 ± 1.7 mm were present from May 22. Growth was rapid from May 22 to July 2 with a maximum daily growth rate of 39%. Median diameter of the medusae was 161.80 ± 18.39 mm at the beginning of July. In August, a high proportion of deteriorated specimens was observed and the median diameter decreased. The highest average abundance is 0.62 ± 1.06 ind/km2 in Jiaozhou Bay in August. The abundance of Aurelia sp.1 medusae was low from September and then decreased to zero. It is concluded that water temperature is the main driver regulating the life cycle of Aurelia sp.1 in Jiaozhou Bay.

Daily growth rates and hatch date distributions of common two-banded seabream, Diplodus vulgaris inhabiting the Çanakkale shallow waters of Turkey

Otolith microstructure analysis was used to determine daily age, growth rate and hatching periods of young of the year (YOY) common two-banded seabream, Diplodus vulgaris, collected at two sites by using beach seine from Çanakkale shallow waters between January and December 2007. Total length of the YOY D. vulgaris was between 12 and 86 mm and the daily ages ranged between 42 and 313 days. Somatic growth rate estimated by fitting a linear regression to the age–length data set was calculated as 0.273 mm day−1. According to the length–age regression analysis, maximum daily growth rates were found 0.277 mm day−1 in the lowest sea temperature period and minimum values of 0.274 mm day−1 were observed in the declining sea temperature period. Analysis of covariance indicated that there were no significant differences in the linear growth equations for the two cohorts (F = 0.4008, P = 0.527). Hatching period of the YOY was estimated to occur between October and March with relatively higher frequency in January. This study has shown that YOY D. vulgaris is a winter spawner in the Çanakkale shallow waters.

Experimental farming of Kappaphycus alvarezii (Doty) Doty with income estimates at different sites in the Mandapam region, Palk Bay, southeast coast of India

The cultivation of Kappaphycus alvarezii, a kappa carrageenan producing red seaweed, was done for 1 year from April 2012 to March 2013 in subtropical waters of Indian Peninsula at three different sites (Mangadu in Rameswaram Island, Munaikadu and Vedalai—on main land coast) on Palk Bay side of Bay of Bengal of Rameswaram–Mandapam region of southeast coast of India. These experiments were carried out to confirm the results obtained in an earlier study (April 2011 to March 2012) at more or less the same sites—one is different (Mangadu) and two are the same (Munaikadu and Vedalai). The maximum crop yields of 326.55 ± 10.23 and 316.65 ± 15.13 kg FW raft−1 were obtained in October 2012 at Mangadu and Munaikadu, respectively, and 308.40 ± 8.89 kg FW raft−1 in March 2013 at Vedalai. Similarly the maximum daily growth rates (DGRs) of 3.76 ± 0.07 and 3.69 ± 0.11 % were found in October 2012 at Mangadu and Munaikadu, and 3.64 ± 0.06 % was obtained in March 2013 at Vedalai. A significant negative correlation between DGR and seawater temperature at Mangadu (r = −0.604) and Munaikadu (r = −0.700) was found (at 0.05 level). Further, a significant positive correlation was seen (at 0.05 level) between nitrite and phosphate at Mangadu (r = +0.613) and Vedalai (r = +0.599). However, salinity and seawater temperature were significantly positively correlated (r = +0.693) at Munaikadu (at 0.05 level). ANOVA showed that the growth rates among these three sites were found to be statistically insignificant. Tip grazing by Siganus javus and Diodon holocanthus during the monsoon period (October 2012 to January 2013) was observed. Seasonal epiphytes Lyngbya majuscula and Cladophora facsicularis were the main problematic epiphytes from April to June. Net income would be Rs15,000 to Rs16,000 (US$250–US$265) per month, and if the cultivation is taken up in earnest perspective, the farmers would improve their living standards.

Seasonal variation in growth and carrageenan yield in cultivated Kappaphycus alvarezii (Doty) Doty on the coastal waters of Ramanathapuram district, Tamil Nadu

Kappaphycus alvarezii, a kappa carrageenan yielding red seaweed, was cultivated in Indian subtropical waters on the Palk Bay side of Bay of Bengal in Ramanathapuram district, Tamil Nadu, at three different sites: Vedalai, Munaikadu, and Thonithurai, for 1 year from April 2011 to March 2012. The maximum crop yields of 416 ± 51 and 550 ± 41 FW raft−1 were recorded at Vedalai and Munaikadu, respectively, in December 2011, whereas a maximum of 326 ± 49 FW raft−1 was recorded at Thonithurai in April 2011. Similarly, the maximum daily growth rates (DGRs) of 4.30 ± 0.51 % and 4.92 ± 0.40 % were obtained at Vedalai and Munaikadu, respectively, in December 2011, and 3.76 ± 0.48 % was recorded at Thonithurai in April 2011. Variations in environmental parameters like seawater temperature, salinity, nitrate, and phosphate were found to influence the growth of the seaweed. The maximum carrageenan content as a percentage of dry weight was 29.30 ± 0.61 % (Vedalai), 31.00 ± 0.71 % (Munaikadu), and 29.10 ± 1.12 % (Thonithurai) in March 2012. The data on moisture content (%), clean anhydrous weed/salt ratio, and carrageenan yield obtained in this study fulfilled those of international standards. Further, the results indicated that large-scale cultivation by either NGOs or self-help groups (SHGs) may be taken up along the coastal waters for the benefit of the poverty-stricken coastal people as their livelihood, as the growth rate obtained in this study compared well with that recommended for commercial cultivation elsewhere.