In utero domoic acid toxicity: a fetal basis to adult disease in the California sea lion (Zalophus californianus)

California sea lions have been a repeated subject of investigation for early life toxicity, which has been documented to occur with increasing frequency from late February through mid-May in association with organochlorine (PCB and DDT) poisoning and infectious disease in the 1970's and domoic acid poisoning in the last decade. The mass early life mortality events result from the concentrated breeding grounds and synchronization of reproduction over a 28 day post partum estrus cycle and 11 month in utero phase. This physiological synchronization is triggered by a decreasing photoperiod of 11.48 h/day that occurs approximately 90 days after conception at the major California breeding grounds. The photoperiod trigger activates implantation of embryos to proceed with development for the next 242 days until birth. Embryonic diapause is a selectable trait thought to optimize timing for food utilization and male migratory patterns; yet from the toxicological perspective presented here also serves to synchronize developmental toxicity of pulsed environmental events such as domoic acid poisoning. Research studies in laboratory animals have defined age-dependent neurotoxic effects during development and windows of susceptibility to domoic acid exposure. This review will evaluate experimental domoic acid neurotoxicity in developing rodents and, aided by comparative allometric projections, will analyze potential prenatal toxicity and exposure susceptibility in the California sea lion. This analysis should provide a useful tool to forecast fetal toxicity and understand the impact of fetal toxicity on adult disease of the California sea lion.

Histological techniques for marine bivalve mollusks and crustaceans, 2nd edition

Investigators at the Cooperative Oxford Laboratory (COL) diagnose and study crustaceans, mollusks, finfish, and a variety of other marine and estuarine invertebrates to assess animal health. This edition updates the Histological Techniques for Marine Bivalve Mollusks manual by Howard and Smith (1983) with additional chapters on molluscan and crustacean techniques. The new edition is intended to serve as a guide for histological processing of shellfish, principally bivalve mollusks and crustaceans. Basically, the techniques included are applicable for histopathological preparation of all marine animals, recognizing however that initial necropsy is unique to each species. Photographs and illustrations are provided for instruction on necropsy of different species to simplify the processing of tissues. Several of the procedures described are adaptations developed by the COL staff. They represent techniques based on principles established for the histopathologic study of mammalian and other vertebrate tissues, but modified for marine and aquatic invertebrates. Although the manual attempts to provide adequate information on techniques, it is also intended to serve as a useful reference source to those interested in the pathology of marine animals. General references and recommended reading listed in the back of the manual will provide histological information on species not addressed in the text.

Larval development of the sidestriped shrimp (Pandalopsis dispar Rathbun) (Crustacea, Decapoda, Pandalidae) reared in the laboratory

Larval development of the sidestriped shrimp (Pandalopsis dispar) is described from larvae reared in the laboratory. The species has five zoeal stages and one postlarval stage. Complete larval morphological characteristics of the species are described and compared with those of related species of the genus. The number of setae on the margin of the telson in the first and second stages is variable: 11+12, 12+12, or 11+11. Of these, 11+12 pairs are most common. The present study confirms that what was termed the fifth stage in the original study done by Berkeley in 1930 was the sixth stage and that the fifth stage in the Berkeley’s study is comparable to the sixth stage that is described in the present study. The sixth stage has a segmented inner flagellum of the antennule and fully developed pleopods with setae. The ability to distinguish larval stages of P. dispar from larval stages of other plankton can be important for studies of the effect of climate change on marine communities in the Northeast Pacific and for marine resource management strategies.

Hermaphroditism in some marine animals

Hermaphroditism, a phenomenon in which one and the same individual produces sperms, the male gamate the ovum, the female gamate, is generally common in plants and lower animals and hence is considered as a primitive character. However, it is rare in higher invertebrates such as insects, spiders, prawns and also in the lower vertebrates to which fishes belong. Prawns and fishes have highly evolved reproductive systems and occur as separate individuals of males and females. Both these groups do have some species which are regurarly hermaphrodites and others which are teratologically hermaphrodites.

Laboratory reared eggs and larval stages of the clupeid fish, Opisthopterus tardoore (Cuvier)

The early embryonic and larval stages of Opisthopterus tardoore are described and discussed. The developing 3 eggs of stages up to 21hrs after collection and larvae up to 118hrs after hatching were reared in the laboratory. Seasonal occurrence of the eggs in the Vellar estuary, Porto Novo (lat. 11 29'N; 79 degree 46'E) was recorded for a period of 2 years (Nov. 1977 to Oct. 1979). Variation in myotomic counts in the larvae is critically reviewed with earlier works.

Predation by Channa striatus (Bloch) on Rana tigrina (Daudin), Puntius gonionotus (Bleekeer) and Labeo rohita (Hamilton) in the laboratory

The growth performance of a predatory snakehead, Channa striatus was tested by supplying tadpoles of Rana tigrina and fingerlings of Puntius gonionotus and Labeo rohita as prey for a period of 21 days in aquaria. Prey consumption by C. striatus was significantly different (P<0.05) for different prey used (T1 - R. tigrina, T2 - P. gonionotus, T3 - L. rohita). Tadpoles of R. tigrina were preferred by the predator (C. striatus) over P. gonionotus and L. rohita although tadpole is nutritionally inferior to each of P. gonionotus and L. rohita. Each predator rayed on 50-330 mg per day per g of their body weight. Fish preyed on tadpoles also showed the highest growth. Significant difference in weight gain was found between T1 and T2 and also between T1 and T3 but no difference was found between T2 and T3. Food conversion ratio (FCR) was found to be lowest in treatment T3 followed by the treatments T2 and T1 respectively.

Domestication of an endangered fish species Nandus nandus (Ham.). Pt. 1. Laboratory rearing of young fish up to sexual maturity

An experiment was conducted for rearing of Meni, Nandus nandus in laboratory condition for seven months with the objective to select appropriate feed for the species and to develop a rearing technique of the species up to the stage of sexual maturation. Different trials were conducted using artificial feed (35.5% protein), dead fresh kachki (Carica soborna), dead fresh prawn (Macrobrachium lamarrei) and live prawn (Macrobrachium lamarrei). The provision of bottom sediment did not significantly influence the growth of fish. Between dead fresh kachki and dead fresh prawn, the fish preferred dead fresh prawn. The fish was found to be reluctant to take dead fresh kachki and prawn as food unless they became very hungry. The fish was found actively feeding on live prawn. The FCR of the prawn as food for N. nandus was found to be 2.5. From the study, it was observed that in laboratory rearing N. nandus preferred live prawn as food than artificial feed, dead fresh kachki and dead fresh prawn. The fish fed on live prawn became sexually matured (eggs or white milt extruded by gentle pressure on the abdomen of the fish) in the laboratory at the end of the experiment.

Effect of some environmental factors on the acute toxicity of deltamethrin to common carp: a laboratory study under aerobic condition

The toxicity of xenobiotic in aquatic ecosystems is influenced by many factors such as ambient temperature, water hardness, pond soil type, etc. In the present study, it was observed that air temperature, water hardness and soil sediment have profound influence on the toxicity of deltamethrin to common carp fry (ay. length 3.5 ± 0.5 cm, ay. weight 0.58 ± 0.25 g); 96h LC(sub)50 values for common carp at 38.07 ± 2.20°C maximum and 27.86 ± 1.22°C minimum air temperature in soft and very hard water were 0.102 and 0.495 µg lˉ¹, respectively. This value had increased significantly to 2.37 and 3.02 µg at 30.55 ± 1.21°C maximum and 26.04 ± 0.61°C minimum air temperature, respectively. When sediment was included, 96h LC(sub)50 at 38.07°C maximum temperature in very hard water was 1.808 µg 1ˉ¹ and this had increased to 8.073 µg 1ˉ¹ when tested at 30.55°C maximum temperature. Due to the 7.5°C increase in maximum and 1.7°C in minimum temperature, toxicity increased significantly. Lower toxicity in very hard water in comparison to soft water may be due to the lower solubility of deltarnethrin and high level of calcium. Adsorption reaction of deltamethrin with clay, humus, FeOOH, MnOOH and particulate organic carbon, and complexation reaction with dissolved organic carbon were responsible for the lowered toxicity in the experiment with sediment. Exposure time had no significant effect on acute toxicity of deltamethrin.