Shell occupation pattern by the hermit crab Diogenes alias McLaughlin & Holthuis, 2001 (Diogenidae) from Mumbai, India

766-773The purpose of this study was to ascertain shell occupation patterns by the hermit crab; Diogenes alias found inhabiting the subtidal region of Mumbai, northwest coast of India. A total of 385 samples of D. alias, occupying different molluscan shells, were collected bi-weekly from trawling operations off Mumbai. The species was found to occupy the shells of 12 gastropods species, of which, the most commonly occupied shells were that of Tibia curta (38.7 %) followed by Indothais lacera (36.37 %) while the shells of Rapana rapiformis and Turris spp. were least occupied with 0.26 %. The diversity of shells occupied by male was higher than female and least in ovigerous females. A high correlation was found between the internal volume of shell and weight of hermit crab occupying it. The present study concluded that the shell architecture has influence on the shell occupation by hermit crabs

Marine ornamental fish trade in Kerala, India: A demand-supply analysis

The significant revenue involved in marine aquarium trade notwithstanding, in developing countries generates gainful employment and alternate livelihood in rural sector to fishers. Despite rich biodiversity of marine ornamental fishes and ideal milieu for expansion of trade the sector remains at infancy. However, absence of primary database on marketing is a major handicap in expansion and regulation of this sector. This study focused on status of demand, supply and potentials of marine aquarium fish trade. The study covered demand and supply entities including suppliers, hobbyists and aquarium keepers. The results documents prominence of aquarium industry and portray the challenges in expanding domestic trade in Kerala. The preferred candidates in trade in Kerala include damsel fish, wrasse, butterfly fish, trigger fish and cardinal fishes. Hobbyist‚ awareness, interests and willingness to keep marine fishes was high despite negligible trade. The demand and purchasing power of hobbyists is undoubtedly the single most important force in determining potential and profitability of marine aquarium industry in Kerala. Maintenance and upkeep snags, technological lag, institutional support and high mortality were the major problems in the sector. The resources are currently being unexploited or discarded. The sector could provide alternative avocation for fishermen if state of art technologies for collection, handling and transport are developed integrating with conservation and sustainable development objectives. The marine aquarium trade of Kerala needs to capitalize on key strength of unexploited resources by alleviating major weaknesses of technological lag and harnessing the opportunities of tapping the huge demand for improving trade.Keywords: The Economics of Aquaculture Production and Profitability Part III, Fish & Aquaculture Sectors' Development, Fisheries EconomicsKeywords: The Economics of Aquaculture Production and Profitability Part III, Fish & Aquaculture Sectors' Development, Fisheries Economic

Low pressure plasma nitrided CoCrMo alloy utilising HIPIMS discharge for biomedical applications

CoCrMo is a biomedical grade alloy which is widely used in the manufacturing of orthopaedic implants such as hip and knee replacement joints because of it has high hardness, high corrosion resistance, and excellent biocompatibility. However, the release of metal ions due to corrosion and wear of the alloy over time may cause allergic or other adverse reactions in some patients. To date, various surface modification techniques including nitriding, have been used to improve the performance of CoCrMo (F75) alloy. In the current work, a new low-pressure plasma nitriding process is described. Unlike conventional plasma nitriding, the process utilises High Power Impulse Magnetron Sputtering (HIPIMS) discharge, sustained on one Cr target at low power, to further enhance the ionisation of the gas in the vacuum chamber and to avoid coating deposition. The nitriding of CoCrMo alloy has been carried out in a wide range of nitriding voltages (from -500 V to -1100 V) at 400 °C for duration of 4 hours. The chemical and phase composition of the nitrided layer has been studied by various advanced surface analyses techniques. The X-ray diffraction data of all the nitrided samples revealed the formation of expanded austenite (γN) phase. Texture analyses revealed that at lower nitriding voltages (-700 V) the predominant crystallographic orientation of the compound layer is (200) whereas at higher voltages (-900 V to -1100 V) the layer develops mixed (111) and (200) texture. For samples nitrided at a lower bias voltage of - 500 V, diffraction peaks for CrN/NbN and Cr2N were also observed due to the deposition of target materials (Cr and Nb). However, no coating deposition on the substrate surface was observed at higher bias voltages (-700 V and higher) due to sufficient re-sputtering effect. The results obtained from glow discharge optical emission spectroscopy (GDOES) depth profiling showed that the depth of nitriding increased from approximately 0.7 µm at -500 V to 6 µm at -1100 V. In the pin-on-disc tribological test nitrided samples showed low coefficient of friction µ in the range of 0.6 to 0.7, compared to µ= 0.8 recorded for the untreated substrate. The wear coefficients (Kc) were found to be between 1.79 × 10-15 m3N -1m-1 (-700 V) and 4.62 × 10- 15 m3N -1m-1 (-1100 V), which were one order of magnitude lower than the untreated substrate, Kc = 6 ×10-14 m3N -1m-1 . The Knoop microhardness (HK) of nitrided samples significantly increased by a factor of 5 (HK= 2750 at -1100 V) as compared to the untreated substrate, HK=525, demonstrating the high efficiency of the process. The samples nitrided at -700 V and - 900 V exhibited enhanced corrosion resistance as compared to untreated alloy by avoiding the formation of CrN based compounds which adversely affect the corrosion performance

A checklist of fishes of Kerala, India

A checklist of the fishes of Kerala State is presented, along with their scientific and common names (English and Malayalam), endemism, IUCN Red List status, listing under different Schedules of the Indian Wildlife (Protection) Act and in the Appendices of Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Nine Hundred and five species of fishes are recorded from the inland and marine waters of Kerala comprising of 41 orders and 172 families. Close to 30% of the freshwater fish species found in Kerala are endemic to the State. Only 8% of the total fishes of Kerala are listed as threatened in the IUCN Red List, of which the majority are freshwater species. Several hundred fish species occurring in the marine waters of Kerala have not yet been assessed for their conservation status by IUCN.  </div

Ethological studies of the Veined Octopus <i>Amphioctopus marinates</i> (Taki) (Cephalopoda: Octopodidae) in captivity, Kerala, India

Five Veined Octopus Amphioctopus marginatus (Taki), collected from Vizhinjam Bay in the Thiruvananthapuram District of Kerala, India were kept in aquariums to study their behaviour in captivity. Primary and secondary defence mechanisms studied included crypsis, hiding and escape behaviour. Deimatic behaviour was used by captive animals when camouflage failed and they were threatened. Crawling behaviour to escape from the aquarium was observed in all specimens. Stilt walking and bi-pedal locomotion were also observed. As a defence behaviour, A. marginatus used aquarium rocks to protect the soft underside of their bodies. A. marginatus demonstrated tool use of coconut shells to make protective shelters, carrying the shells for future use. A female specimen also selected a coconut shell for egg laying and performed parental care by continuously cleaning and aerating her eggs with her arms and by squirting jets of water over the eggs

New records of hermit crabs, <i>Calcinus morgani</i> Rahayu and Forest, 1999 and <i>Diogenes klaasi</i> Rahayu and Forest, 1995 (Crustacea: Anomura: Diogenidae) from India

Two species of hermit crabs, Calcinus morgani Rahayu and Forest and Diogenes klaasi Rahayu and Forest of the family Diogenidae, are recorded for the first time from the Indian coast. Calcinus morgani inhabits the intertidal rocky area along Thirumullavaram beach, Kollam, while D. klaasi was collected from the mangrove swamps in Ashtamudi Lake, Kerala

Comparison of intertidal biodiversity associated with natural rocky shore and sea wall: A case study from the Kerala coast, India

223-235Intertidal biodiversity associated with natural rocky shore at Kovalam and artificial sea wall at Vizhinjam, Thiruvananthapuram district of Kerala, was compared during the study. A total of 147 species, including 32 seaweeds, 11 sponges, 6 coelenterates, 2 bryozoans, 31 molluscs, 7 annelids, 2 sipunculids, 6 isopods, 12 amphipods, 1 hermit crab, 16 brachyuran crabs, 4 alpheid shrimps, 1 barnacle, 9 echinoderms and 7 species of ascidians were recorded. While the intertidal biodiversity from the sea wall was represented by 73 species, 128 species were recorded from the rocky shore. The anomuran crab Clibanarius virescens (Krauss), the brachyuran crabs Acetea depressa (White), Micropanape obtusidens (Sakai), Sargassocarcinus cristatus (Balss) and Eurynome orientalis (Sakai) and the alpheid shrimps, <i style="mso-bidi-font-style: normal">Synalpheus stimpsonii De Man and Alpheus lottini  Guérin-Méneville are reported for the first time in India. Shannon and richness index values were higher for the rocky shore, while the species dominance was higher in the sea wall

The Fish Fauna of Bharathapuzha River, Kerala

Volume: 98Start Page: 464End Page: 46

Morphometry and meristics of longnose seahorse, Hippocampus trimaculatus (Actinopterygii: Syngnathidae), from Kerala, south-west coast of India

Background. The longnose seahorse, Hippocampus trimaculatus Leach, 1814, included in the Red List of Threatened Species is the most common and least studied seahorse species along the south-west coast of India. Practically no information is available on numerical taxonomy and sexual dimorphism of H. trimaculatus from India. The purpose of the reported study is to describe the morphometry and meristics of H. trimaculatus occurring along Kerala, south-west coast of India. Materials and methods. A total of 45 specimens of H. trimaculatus, represented by 25 males and 20 females, obtained from trawl by-catch, were studied following standard morphometric and meristics procedures. Statistical data analyses include Student’s t-test, Mann–Whitney U test, and Principal Component Analysis to describe the sexual dimorphism of the species. Results. Male H. trimaculatus are longer than females, with relatively longer tails. The mean values of head depth, snout depth, trunk depth, trunk width, dorsal fin base length, and pectoral fin base length are higher in males, while head length, snout length, coronet height, and trunk length are higher in females. Trunk length and snout depth are the two principal components that determine sexual dimorphism in H. trimaculatus. Conclusion. The numerical taxonomy of H. trimaculatus from Indian coastal waters is reported for the first time. The study shows that sexual dimorphism in H. trimaculatus is reflected in differing morphometric characters between the sexes

On the molluscan fauna of Lakshadweep included in various schedules of Wildlife (Protection) Act of India

Out of the 24 species of marine molluscs included in Schedule I and IV of the Wildlife (Protection) Act (WPA) of India, 19 species were recorded from the coastal waters of Lakshadweep.  A recent survey conducted by the authors recorded the presence of 14 scheduled molluscs in Lakshadweep.  Scheduled species such as Placuna placenta (recorded from Kavaratti) and Tudicla spirillus (recorded from Kalpeni) are new records from Lakshadweep.  The paper provides details for taxonomic identification of scheduled molluscs and discusses strategies for conservation of scheduled molluscs of Lakshadweep. </p