Reproductive biology and larval rearing of Hippocampus kuda, and the taxonomy of seahorses (hippocampus spp.) along the southern coast of India (TH 124)

An organised fishery and trade of seahorses exist in the Palk Bay and Gulf of Mannar coasts of India. Six species of seahorses namely Hippocampus borboniensis Dumeril 1870, Hippocampus spinosissimus Weber 1913, Hippocampus kuda Bleeker 1852, Hippocampus fuscus Ruppell 1838, Hippocampus trimaculatus Leach 1814 and Hippocampus guttulatus Cuvier 1829 were identified from the southern coast, and the total landing at the major fishing centre, Thondi was estimated as 18.25 MT or 26,48,179 numbers of seahorses during 2001 . The volume of seahorse trade from India was estimated as 9.75 MT of dried seahorses. A significant quantity of 1.6 MT (5,61,418 numbers) is also landed along the Quilon coast in Keraia, but it is not involved in any organised trade. H. borboniensis was found to be the major species (27.96%) at Thondi, followed by H. spinosissimus (22.14%). H. kuda (20.9%) , H. trimaculatus (14%) , H. fuscus (9%) and H. guttulatus (4%) . The major size classes represented in the fishery were 145-175 mm, 145-165 mm, 105-190 mm, 110-165 mm, 140-190 mm and 150-190 mm respectively for the six species collected from Thondi in 2001 . Crustaceans (88.85%) , consisting of cope pods (22.8%)' mysids and cumaceans (22.12%), amphipods and isopods (20.86%), decapod larvae and tiny caridean shrimps (20.67%) dominated the gut contents of H. kuda at Thondi. Ova diameter ranged from 0.5-0.8 mm and the mean fecundity was 56.8 g-1 body weight of the female. The length-weight relationships were obtained as W = 0.438615 (L 1.103592) for males, and W = 0.370531 (L 1.231822) for females of H. kuda collected from Thondi. The size at first maturity for males and -females of H. kuda was found to be 66.07 mm and 77.99 mm for males and females respectively. At Thondi H. kuda was fo_und to breed year round, the major breeding season extending from June to September with peak from July to August. The sex ratio remained almost the same, except during the breeding season when more males were seen in the catches. The captive rearing of the hatchlings of H. kuda using different feeds showed that a diet of enriched Artemia nauplii and mixed marine copepods was the best combination, which gave mean survival rates of up to 56% and growth of 49.4 mm and 0.316 g after 60 days of rearing. A stocking density of 3 juveniles per litre was found to be the optimum, which gave high growth increment in length (43.67 mm) and weight (0.313 g) as well as the highest mean production per litre of 1.51 during a rearing period of 60 days. The juveniles of H. kuda were found to grow equally well in salinities ranging from 15 %0 to 35 %0. The highest mean survival (60.56%). mean length (28.7 mm) and mean weight (39.1 mg) were obtained at 30 %0 while rearing for 14 days. Rearing tanks, which were partially covered to improve the feeding efficiency of Artemia nauplli registered the highest mean survival (91%) and mean length (36.2 mm) and weight (66.14 mg) of juveniles during a 14-day period. The juveniles of H. kuda were found to have reasonably high tolerance to extreme levels of salinity, pH and formalin. The LCso values were 4.62, 4.83, 5.43 and 5.56 for low pH and 11 .04,10.52,10.33 and 10.23 for high pH at 12, 24 48 and 72 h respectively. In the case of salinity, LCso values of 1.59, 2.92, 3.63 and 4.67 %0 for low salinity, and 58.08, 54.45, 51 .29 and 49.26 %0 for high salinity were obtained for 12, 24, 48 and 72 h respectively. The LCso for formalin was found to be 315, 296.48, 279.25 and 271 .02 ppm for 12, 24, 48 and 72 h respectively

Fisheries and trade of seahorses, Hippocampus spp., in southern India

Seahorses (Hippocampus spp.) are in much demand for traditional medicines and curios in dried form, and as aquarium fish when alive. Shallow seas abundant in sea grasses, sponges and corals characterise the natural habitats of the seahorses (Vincent 1994, 1995). All seahorses (Syngnathidae) belong to one genus Hippocampus. There are about 33 species of seahorses worldwide (Lourie, Vincent & Hall 1999; Lourie & Randall 2003). Seahorses are unique in their reproductive behaviour, in which the males become pregnant. The male fertilises and broods the eggs produced and deposited into its pouch by the female during courtship and mating, and in turn delivers the hatchling, after a long period of pregnancy and labour. Most species of seahorses studied so far show unique sexual fidelity and form faithful pair bonds (Vincent & Sadler 1995), in which case one male and one female mate repeatedly and exclusively giving up opportunities to interact with non-partners

Captive rearing of Hippocampus kuda and issues of seahorse conservation in India

Captive breeding and rearing of Hippocampus kuda, onc of the most dominant species of seahorscs was done to determine the optimum conditions of rearing, which would give the bighestsurvival, and growth of juveniles. A diet or enriched Artemia and mixed marine copepods was found to be the best feed combination during a rearing period 01'60 days. A stocking density 01'3 juveniles per litre was found to be the optimum, which gave the highest mean incrcment of growth in length and weight, as well as the highest mean production per litre

Pattern of Reaction Diffusion Front in Laminar Flows

Autocatalytic reaction between reacted and unreacted species may propagate as solitary waves, namely at a constant front velocity and with a stationary concentration profile, resulting from a balance between molecular diffusion and chemical reaction. The effect of advective flow on the autocatalytic reaction between iodate and arsenous acid in cylindrical tubes and Hele-Shaw cells is analyzed experimentally and numerically using lattice BGK simulations. We do observe the existence of solitary waves with concentration profiles exhibiting a cusp and we delineate the eikonal and mixing regimes recently predicted.Comment: 4 pages, 3 figures. This paper report on experiments and simulations in different geometries which test the theory of Boyd Edwards on flow advection of chemical reaction front which just appears in PRL (PRL Vol 89,104501, sept2002

Resonance production by neutrinos: I. J=3/2 Resonances

The article contains general formulas for the production of J=3/2 resonances by neutrinos and antineutrinos. It specializes to the P_{33}(1232) resonance whose form factors are determined by theory and experiment and then are compared with experimental results at low and high energies. It is shown that the minimum in the low Q^2 region is a consequence of a combined effect from the vanishing of the vector form factors, the muon mass and Pauli blocking. Several improvements for the future investigations are suggested.Comment: 10 pages, LaTeX, misprints corrected, 1 reference adde

Time-dependent density-functional theory approach to nonlinear particle-solid interactions in comparison with scattering theory

An explicit expression for the quadratic density-response function of a many-electron system is obtained in the framework of the time-dependent density-functional theory, in terms of the linear and quadratic density-response functions of noninteracting Kohn-Sham electrons and functional derivatives of the time-dependent exchange-correlation potential. This is used to evaluate the quadratic stopping power of a homogeneous electron gas for slow ions, which is demonstrated to be equivalent to that obtained up to second order in the ion charge in the framework of a fully nonlinear scattering approach. Numerical calculations are reported, thereby exploring the range of validity of quadratic-response theory.Comment: 14 pages, 3 figures. To appear in Journal of Physics: Condensed Matte

Nucleon to Delta Weak Excitation Amplitudes in the Non-relativistic Quark Model

We investigate the nucleon to Delta(1232) vector and axial vector amplitudes in the non-relativistic quark model of the Isgur-Karl variety. A particular interest is to investigate the SU(6) symmetry breaking, due to color hyperfine interaction. We compare the theoretical estimates to recent experimental investigation of the Adler amplitudes by neutrino scattering.Comment: \documentstyle[aps]{revtex}, 21pages; 11 postscript figures. Accepted for publication by Phys. Rev.

A simple spontaneously active Hebbian learning model: homeostasis of activity and connectivity, and consequences for learning and epileptogenesis

A spontaneously active neural system that is capable of continual learning should also be capable of homeostasis of both firing rate and connectivity. Experimental evidence suggests that both types of homeostasis exist, and that connectivity is maintained at a state that is optimal for information transmission and storage. This state is referred to as the critical state. We present a simple stochastic computational Hebbian learning model that incorporates both firing rate and critical homeostasis, and we explore its stability and connectivity properties. We also examine the behavior of our model with a simulated seizure and with simulated acute deafferentation. We argue that a neural system that is more highly connected than the critical state (i.e., one that is "supercritical") is epileptogenic. Based on our simulations, we predict that the post-seizural and post-deafferentation states should be supercritical and epileptogenic. Furthermore, interventions that boost spontaneous activity should be protective against epileptogenesis.Comment: 37 pages, 1 table, 7 figure

Oxidative stress and life histories: unresolved issues and current needs

Life-history theory concerns the trade-offs that mold the patterns of investment by animals between reproduction, growth, and survival. It is widely recognized that physiology plays a role in the mediation of life-history trade-offs, but the details remain obscure. As life-history theory concerns aspects of investment in the soma that influence survival, understanding the physiological basis of life histories is related, but not identical, to understanding the process of aging. One idea from the field of aging that has gained considerable traction in the area of life histories is that life-history trade-offs may be mediated by free radical production and oxidative stress. We outline here developments in this field and summarize a number of important unresolved issues that may guide future research efforts. The issues are as follows. First, different tissues and macromolecular targets of oxidative stress respond differently during reproduction. The functional significance of these changes, however, remains uncertain. Consequently there is a need for studies that link oxidative stress measurements to functional outcomes, such as survival. Second, measurements of oxidative stress are often highly invasive or terminal. Terminal studies of oxidative stress in wild animals, where detailed life-history information is available, cannot generally be performed without compromising the aims of the studies that generated the life-history data. There is a need therefore for novel non-invasive measurements of multi-tissue oxidative stress. Third, laboratory studies provide unrivaled opportunities for experimental manipulation but may fail to expose the physiology underpinning life-history effects, because of the benign laboratory environment. Fourth, the idea that oxidative stress might underlie life-history trade-offs does not make specific enough predictions that are amenable to testing. Moreover, there is a paucity of good alternative theoretical models on which contrasting predictions might be based. Fifth, there is an enormous diversity of life-history variation to test the idea that oxidative stress may be a key mediator. So far we have only scratched the surface. Broadening the scope may reveal new strategies linked to the processes of oxidative damage and repair. Finally, understanding the trade-offs in life histories and understanding the process of aging are related but not identical questions. Scientists inhabiting these two spheres of activity seldom collide, yet they have much to learn from each other