Gonadal Production Research Articles

Temperature Effect on Feed Consumption, Absorption, and Assimilation Efficiencies and Production of the Sea UrchinStrongylocentrotus intermedius

ABSTRACT Strongylocentrotus intermedius is a widespread sea urchin species in Asian waters and experiences a large seasonal variation in temperature. It is essential to understand how temperature affects utilization of nutrients and production. Large (5 cm test diameter) S. intermedius were maintained in the laboratory and fed a formulated feed from 28 February when the gonads were small (gonad index, GI, ∼10) and sea water temperature was low (7°C) until 27 June when sea water temperature was high (24°C) under five temperature treatments (environmental temperature, 7, 12, 17 and 22°C. Temperature had little effect on rate of consumption of food or absorption efficiency and little effect on assimilation efficiency except for a significant decrease at 22°C. The gonad index was consistently least at 22°C. Organic matter production in the gonads was greatest and earliest (April) at 12 and 17°C. Strongylocentrotus intermedius acclimated to temperature <22°C during the season of gonad production. These data in...

Dietary phospholipids affect growth and production of juvenile sea urchin Lytechinus variegatus

To facilitate sea urchin aquaculture, nutritionally-complete feeds are being developed for a number of species. In this study, the effects of dietary phospholipids from soy lecithin on weight gain and production were investigated to ascertain a potential dietary requirement for small juvenile sea urchins, Lytechinus variegatus. Laboratory-produced juvenile L. variegatus ( n = 16 per treatment, average 0.091 g ± 0.01 SE wet weight and 5.80 mm ± 0.09 SE diameter) were fed semi-purified formulated diets supplemented with 1, 2.5, 4, 5.2, 6.4, 7.6, or 8.8% phospholipids (as fed) from soy lecithin for 12 weeks. Under the conditions of this study, a negative correlation between dietary phospholipid level and weight gain was observed. By 6 wk and continuing through 12 wk, sea urchins fed the 1 to 6.4% supplemented phospholipid diet (SPLD) had significantly higher total wet weight than sea urchins fed either the 7.6 or 8.8% SPLD (final wet weight ranged from 10.53 ± 0.41 g to 7.42 ± 0.65 g, for the 1 and 8.8% treatments, respectively, P < 0.05). Feed intake and apparent dry matter digestibility coefficients were similar among the 1, 5.2, and 8.8% SPLD treatments. A requirement for greater than 1% dietary phospholipid derived from soy lecithin could not be determined. Gonad production was observed at 12 wk. No significant differences were observed for ovary wet or dry weight; however, testis wet weight was higher for males fed the 1% SPLD than males fed the 8.8% SPLD (ANOVA, P < 0.05). In the gut, nonpolar lipid levels were highest for individuals fed the 8.8% SPLD (4.6, 5.4, and 10.6% for 1, 5.2, and 8.8% SPLD, respectively), indicating conversion of phospholipid to nonpolar lipid, presumed to be stored as triacyglycerols. In the ovary and testis, polar lipid levels were similar among the three treatments tested (ovary, 9.2, 10.9, 10.3% and testis, 8.1, 9, and 7.6% for 1, 5.2, and 8.8% SPLD, respectively), but nonpolar lipid levels were highest for females and males fed the 8.8% SPLD (ovary, 9.4, 12, and 16.6% and testis, 3.7, 9.4, and 12.7%, respectively). These data suggest that dietary phospholipids are, in part, being metabolized and stored as neutral lipid in the gut and gonad.

Growth assessment on three size classes of the purple sea urchin Paracentrotus lividus using continuous and intermittent feeding regimes

A 6 month experiment (March '05–September, '05) was conducted to assess the somatic and gonadal growth of three different size classes (small, medium and large) of the European sea urchin Paracentrotus lividus under two feeding regimes. For each size class, four replicate cages were fed continuously in which feed was replenished every seven days and four replicate cages were fed intermittently (an alternating weekly regime of feeding/fasting). Test diameter was measured on a monthly basis while gonad index was determined at the end of the experiment. Small sea urchins (10.0–12.9 mm) were significantly affected by intermittent feeding and showed high mortality rates across the experimental period (39.4 ± 3.32%). Continuous feeding supported somatic growth in small and medium sea urchins (10.0–23.0 mm). Feeding regimes did not affect somatic growth of large sea urchins (29.0–33.5 mm). However, large sea urchins on a continuous feeding regime had greater gonad indices (15.76 ± 1.13%) than those on an intermittent regime, which suggests that an intermittent feeding regime cannot support gonadal production.

Effects of competition on sexual and clonal reproduction of a tunicate: the importance of competitor identity

Individual fitness and the structure of marine communities are strongly affected by spa- tial competition. Among the most common space holders are the colonial ascidians, which have the ability to monopolize large areas of hard substrate, overgrowing most other competitors. The effects of competition on colony growth and on gonad production of the ascidian Didemnum perlucidum were studied in southeastern Brazil by experimentally removing surrounding competitors. Colonies of D. perlucidum competing for space exhibited a growth rate 9 times less than that of colonies that were competitor free. Among the colonies subject to competition, growth rates were unrelated to the percentage of colony border that was free of competitors. However, the identity of the competitor was important in the outcome of border contacts. At the beginning of the experiment, most border encounters of D. perlucidum were with solitary organisms, which in most cases were overgrown. These were progressively replaced by colonial ascidians and bryozoans, resulting mostly in stand-off interactions. Besides reducing asexual growth, spatial competition also affected female gonad pro- duction. Colonies free of competitors had a significantly higher proportion of zooids with ovaries. Thus, our findings show that spatial competition reduces both ascidian colony size and gonad production.

In situ study of the autecology of the closely related, co-occurring sandy beach amphipods Bathyporeia pilosa and Bathyporeia sarsi

Population dynamics and zonation of the amphipods Bathyporeia pilosa and B. sarsi, co-occurring on some beaches, were studied through monthly sampling of eight cross-shore transects along the Belgian coast (October 2003-October 2004). Their biomass and produc- tion were assessed for the Wrst time. Abundance and bio- mass of B. pilosa were ten times higher along western ultra- dissipative transects than along slightly more reXective, eastern transects. For B. sarsi (less prominent), diVerences between the two westernmost transects (2-5£ higher) and all others were observed, whereas P/B ratio was compara- ble for all. B. pilosa could reach two times higher abundance and biomass and higher levels of production (max B. sarsi =7 ,580 g m i2 y i1 ; max B. pilosa = 16,040 g m i2 y i1 ), while the species was nearly absent from the eastern transects. Continuous reproduction and with three relative peaks of the latter (February, July, Octo- ber) were observed. Fecundity showed parallel temporal variation for both species, peaking in February and Septem- ber-October. Interestingly, the July relative recruitment peak could not be explained by relative abundance of gravid females or fecundity, but was probably caused by adult mortality. Both species displayed comparable gonad production (B. pilosa: P g = 0.73 mg/ind year; B. sarsi: Pg = 0.71 mg/ind year), but B. pilosa produced fewer yet larger embryos. Peak abundances were found at 436 § 25 SD cm (B. pilosa) and 357 § 40 SD cm (B. sarsi) above MLLWS, corresponding to a 40-62 m cross-shore distance between the peaks of both species. The occupied cross-shore range was larger for B. sarsi than for B. pilosa (35-54 m), for females than for males (15-23 m), and for adults than for juveniles of B. pilosa (5-8 m). Both species displayed many comparable life history features. DiVer- ences in abundance and biomass may be related to beach morphodynamics and zonation.

Sex steroids impact on female sexuality: peripheral and central effects

The increase in female life expectancy during the past century has meant that women now live one-third of their lives beyond cessation of their ovarian function. This evolution in demography has increased the need for the development of new therapeutical strategies to promote successful aging, defined as low probability of disease, high cognitive and physical capacity and active engagement in life. The growth, differentiation, normal physiology and aging of the CNS are all recognized to be influenced by gonadal steroid hormones. Steroids arriving from the gonads via the circulation modulate brain function, affecting gender differentiation and sexually differentiated behavioural responses, but also the ability of the brain to process, store and retrieve sensory information. Sex steroids (estrogen, androgen) play a pivotal neuroactive role during the “organizational/developmental” phase, mainly in the fetal-neonatal period, when participated to the formation of neuronal circuits, as well as during the aging process when it has been demonstrated to directly affect synapse density and remodelling, suggesting a physiopathological role for sex steroids in the modulation and perception of measure of quality of life, cognitive function and development of neurovegetative disease. In postmenopause as well as during ageing process, neurotransmitters, neuropeptides and neurosteroids undergo important changes as a consequence of the failure of gonadal and adrenal hormone production, bringing on specific symptoms due to CNS derangement. Hot flushes, sweat, obesity and hypertension are consequences of the neuroendocrine changes in the hypothalamus. Mood changes, anxiety, depression, insomnia, headaches/migraine, sexual dysfunction are related to postmenopausal alterations of sovrahypothalamic areas. Because changes in the aging nervous system are subtle, it may be possible to reverse them and to improve cognitive and sexual behavioural performance by pharmacological treatments. Though a large attention has been given to the study of postmenopause and to the options in hormone replacement treatment (estrogens and progestins), relative attention and awareness has been focused on the activity of endogenous or exogenous androgens in women. In fact the middle age of women life is characterized by the coexistence of menopause and adrenopause that sometimes both partecipate to create the androgen-deficiency syndrome. Thus, much more interested have been launched to the study of androgen role in the modulation of brain function in term of sexuality, mood, cognition and neuroaging process. The presentation summarize the neuroactive effect of estrogen and androgen in the female body and in particular in female brain with particular regard to their impact of measure of quality of life and sexuality.

Altered reproduction in fish exposed to pulp and paper mill effluents: Roles of individual compounds and mill operating conditions

For the last 20 years, studies conducted in North America, Scandinavia, and New Zealand have shown that pulp and paper mill effluents affect fish reproduction. Despite the level of effort applied, few leads are available regarding the factors responsible. Effluents affect reproduction in multiple fish species, as evidenced by decreased gonad size, decreased circulating and gonadal production of reproductive steroids, altered expression of secondary sex characteristics, and decreased egg production. Several studies also have shown that effluent constituents are capable of accumulating in fish and binding to sex steroid receptors/ binding proteins. Studies aimed at isolating biologically active substances within the pulping and papermaking process have provided clues about their source, and work has progressed in identifying opportunities for in-mill treatment technologies. Following comparisons of manufacturing processes and fish responses before and after process changes, it can be concluded that effluent from all types of mill processes are capable of affecting fish reproduction and that any improvements could not be attributed to a specific process modification (because mills normally performed multiple modifications simultaneously). Improved reproductive performance in fish generally was associated with reduced use of molecular chlorine, improved condensate handling, and liquor spill control. Effluent biotreatment has been effective in reducing some effects, but biotreated effluents also have shown no difference or an exacerbation of effects. The role of biotreatment in relation to effects on fish reproduction remains unclear and needs to be resolved.

Reproductive toxicity of vinclozolin in the fathead minnow: Confirming an anti‐androgenic mode of action

The objective of the present study was to characterize responses of the reproductive endocrine system of the fathead minnow (Pimephales promelas) to the fungicide vinclozolin (VZ), using a 21-d reproduction assay, and a shorter-term (approximately two weeks) test in which fish were cotreated with the VZ (a putative anti-androgen) and the androgen 17beta-trenbolone (TB). Effects on fecundity, gonadal histology, secondary sexual characteristics, reproductive hormones, and relative abundance of androgen receptor (AR) and 11beta-hydroxysteroid dehydrogenase (11betaHSD) mRNA transcripts were evaluated in one or both of these studies. Fecundity of VZ-exposed fish was decreased in a concentration-dependent manner in the 21-d test, culminating in complete reproductive failure at a concentration of 700 microg/L. Exposure to VZ decreased expression of male secondary sexual characteristics -- an effect typical of anti-androgens. The finding that exposure of females to TB-induced expression of prominent, male-like tubercles, which could be effectively blocked with VZ, provides powerful evidence of the anti-androgenic activity of VZ in vivo. In the two experiments VZ produced several responses possibly indicative of compensation or adaptation of the fish to the anti-androgen, including increases in gonad weight, AR and 11 betaHSD mRNA transcript abundance, and ex vivo gonadal production of testosterone and 11-ketotestosterone. Overall, our results demonstrate that the model anti-androgen VZ, which also is an environmental contaminant, impairs reproductive success of fathead minnows and elicits endocrine responses consistent with an anti-androgenic mode of action.

Reproductive potential of a marine ecosystem engineer at the edge of a newly expanded range

AbstractGlobal climate change is leading to redistribution of marine species and altering ecosystem dynamics. Given recent poleward range extension of the barrens‐forming sea urchin Centrostephanus rodgersii (Diadematidae) from mainland Australia to Tasmania, there is a need to understand the population dynamics of this ecologically important species in the Tasmanian environment. This paper informs possible population dynamics of C. rodgersii in Tasmania by examining its reproductive ecology in this new environment. Reproductive periodicity (gonad index and propensity to spawn) was assessed bimonthly over 18 months at four sites in eastern Tasmania spanning ∼2° in latitude. At all sites, C. rodgersii displayed a strong seasonal cycle in gonad production with major spawning occurring in winter (∼August) at minimum annual water temperature. Gametes from Tasmanian C. rodgersii were viable as determined by fertilization and early development trials. However, development to the two‐arm stage at ∼3 weeks was strongly dependent on water temperature across the 8–20 °C temperature range, with poor development occurring below 12 °C. The range of temperatures tolerated by Tasmanian C. rodgersii larvae was similar to that of larvae from its native New South Wales range, indicating that this species has not undergone an adaptive shift to the cooler Tasmanian environment. There was also no evidence for an adaptive shift in reproductive phenology. Importantly, coastal water temperatures in eastern Tasmania during the peak spawning in August fluctuate about the 12 °C larval development threshold. Recent warming of the eastern Tasmanian coast and further warming predicted by global climate change will result in an environment increasingly favourable for the reproduction and development of C. rodgersii.

Food of the sea urchins Strongylocentrotus nudus and Hemicentrotus pulcherrimus associated with vertical distributions in fucoid beds and crustose coralline flats in northern Honshu, Japan

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 352:125-135 (2007) - DOI: https://doi.org/10.3354/meps07121 Food of the sea urchins Strongylocentrotus nudus and Hemicentrotus pulcherrimus associated with vertical distributions in fucoid beds and crustose coralline flats in northern Honshu, Japan Hikaru Endo1,*, Nobuyasu Nakabayashi2, Yukio Agatsuma1, Kazuya Taniguchi1 1Laboratory of Marine Plant Ecology, Graduate School of Agricultural Science, Tohoku University, Aoba, Sendai, Miyagi 981-8555, Japan 2Akita Prefectural Institute of Fisheries, Oga, Akita 010-0531, Japan *Email: lyendoana@bios.tohoku.ac.jp ABSTRACT: The vertical distribution and food of Strongylocentrotus nudus and Hemicentrotus pulcherrimus in fucoid beds at depths of 0.3 to 2.4 m and coralline flats at depths of 2.4 to 4.7 m were studied monthly from May 2001 to May 2002 off the Oga Peninsula, Akita prefecture, northern Japan. No seasonal migration of S. nudus from coralline flats to the fucoid beds occurred, as sufficient food was available in the form of sessile animals. Crustose corallines were generally predominant in the gut contents of sea urchins in fucoid beds, where their density was extremely low. Hemicentrotus pulcherrimus inhabit both fucoid beds and coralline flats. The main foods required for this sea urchin’s gonad production are the dominant algae and sessile animals found in each algal community. The low amounts of fucoids in the gut contents of each species suggest low consumption, possibly because of difficulty in grazing fully grown and erect thalli and feeding deterrents. KEY WORDS: Sea urchin · Strongylocentrotus nudus · Hemicentrotus pulcherrimus · Gut content · Fucoid beds · Gonad development Full text in pdf format PreviousNextCite this article as: Endo H, Nakabayashi N, Agatsuma Y, Taniguchi K (2007) Food of the sea urchins Strongylocentrotus nudus and Hemicentrotus pulcherrimus associated with vertical distributions in fucoid beds and crustose coralline flats in northern Honshu, Japan. Mar Ecol Prog Ser 352:125-135. https://doi.org/10.3354/meps07121 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 352. Online publication date: December 20, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Testicular function in boys previously treated with recombinant-human growth hormone for non-growth hormone-deficient short stature

Data on the effects of recombinant human GH (hGH) therapy during male puberty on future testis function are still inconclusive. The aim of this study was to investigate the long-term effects of recombinant hGH treatment on reproductive function in non-GH-deficient short stature boys. Eight boys with non-GH-deficient short stature, affected by constitutional delay of puberty or idiopathic short stature, were retrospectively studied after recombinant-hGH treatment to verify gonadal development, hormone production and semen quality. Auxological data, endocrinological/ andrological parameters and laboratory evaluation (GH, IGF-I, FSH, LH, testosterone, inhibin B) were assessed before treatment; after completion of pubertal development, the same parameters plus SHBG levels were evaluated and a seminal fluid examination was conducted (ejaculate volume, pH, sperm concentration, total sperm count, forward and total motility, morphology). All patients showed normal testicular volume at the final pubertal stage, with regular androgenization. Hormonal levels were within the normal adult range in all boys. Considering the immature reproductive system of these patients in comparison with adults, semen parameters (sperm count, motility, and morphology) were within almost normal limits, except in one patient. Although patients showed the wide fluctuation of semen values frequently observed at the end of puberty, the hypophysis-gonadal axis hormones were in the normal range in all adolescents. Pathological measurements of some seminal parameters were found in one patient only. This study suggests that recombinant hGH treatment has no detrimental effects on the development and maturation of male gonadal function in non- GH deficient short stature young patients.

Reproductive output and consistency of source populations in the sea star Pisaster ochraceus

Although a common goal of marine reserves is to protect areas of high reproductive out- put, few studies have tested whether these source populations are spatially and temporally consistent. For 6 years between 1995 and 2005, we examined nutrient storage and gonad production in the sea star Pisaster ochraceus at 2 sites on the central coast of Oregon, USA. Sea stars accumulated energy in the pyloric caeca during a short season of intensive feed- ing (May to September). Within a site, the size of the pyloric caeca in the fall accurately predicted repro- ductive output during the following spring. In accord with hypotheses regarding bottom-up effects, the pyloric caeca were generally larger at the site where mussels were more abundant in the diet, indicating a greater accumulation of surplus energy. However, gonad indices were consistently ~50% lower at this site, suggesting striking differences in allocation to reproduction. This difference between populations was maintained despite marked variation among years in oceanographic conditions and reproductive output. These results suggest that (1) source popula- tions may be consistent spatially, but (2) identifying those sources may be more complex than simply tar- geting areas with high quality resources and strong bottom-up influences. Rather, predicting patterns of per capita reproductive output may require a more detailed understanding of the causes of spatial varia- tion in allocation to maintenance, growth, and repro- duction.

Cycle of gonadal development in Eunicella singularis (Cnidaria: Octocorallia): trends in sexual reproduction in gorgonians

Abstract. Eunicella singularis is a gorgonian species whose members are abundant in hard‐bottom sublittoral communities of the Mediterranean Sea. The reproductive biology in this species has been examined to better understand the ability in this species to recover from recent mass mortality events. Eunicella singularis is a stable, gonochoric, iteroparous species that reproduces annually and exhibits a seasonal pattern of gametogenesis characterized by a single annual maturation of the gametes. The sex ratio did not significantly differ from 1:1. Oogenesis lasted 13–17 months, beginning between February and June, and ending with the release of 0.7 planula larvae per polyp between late May and July of the following year. The diameter of mature oocytes ranged 450–860 μm. Spermatogenesis was much shorter than oogenesis and occurred over 5–6 months. Gonadal production of both sexes increased in spring and culminated with the spawning of male colonies in late May–June. Fertilization of oocytes and development of the planula larvae occurred within the polyps of female colonies. Planula release was observed in June and July. The patterns emerging from this and previous studies on sexual reproduction of Mediterranean gorgonians suggest that investment in gonad development appears to be related to resource availability.

Invertebrate fauna associated with kelp enhances reproductive output of the green sea urchin Strongylocentrotus droebachiensis

Kelp beds are species rich communities providing food and shelter for a wide range of invertebrate and fish species. As the dominant subtidal grazer in the northwest Atlantic, the green sea urchin Strongylocentrotus droebachiensis can severely limit the distribution and abundance of kelps and influence the structure of the rocky subtidal community. Urchins form large mobile feeding aggregations (termed fronts) along the margins of kelp beds that destructively graze kelps and, incidentally, the associated invertebrate fauna. Urchins along the leading edge of fronts climb upon and consume kelp fronds and trailing urchins graze the remaining stipes and holdfasts. The fronds are often encrusted with an epiphytic bryozoan Membranipora membranacea, while the holdfasts harbour many sessile and cryptic invertebrates, such as mussels and brittle stars. The effects on urchin growth (as test diameter and body weight) and reproduction (as gonad index) of feeding on kelp fronds or holdfasts, both with or without the natural associated fauna, were examined in a 95-day experiment in the laboratory. Female urchins had a greater gonad index than males in all diet treatments at the end of the experiment. Females fed holdfasts with associated fauna had a greater gonad index that those fed cleaned holdfasts, but there was no difference between these treatments for males. For urchins fed fronds, there was no significant difference in gonad index of either sex between treatments with and without M. membranacea, although urchins fed at a lower rate on bryozoan-encrusted fronds. Test diameter increased by 1–7 mm (based on tank means) during the experiment, but there was no effect of diet or sex on growth rate. The finding that a diet of kelp with naturally associated fauna can significantly enhance gonad production in S. droebachiensis has important implications for the development of optimal aquaculture and harvesting practices.

Food Consumption, Absorption, Assimilation and Growth of the Sea Urchin Strongylocentrotus intermedius Fed a Prepared Feed and the Alga Laminaria japonica

Prepared feeds are standard for developed aquaculture programs. Prepared feeds have been shown to be effective for several species of sea urchins. We investigated the use of prepared feeds for culture of the important commercial species Strongylocentrotus intermedius by comparison with the usual food used, the brown alga Laminaria japonica. The experiment was done in the summer and consisted of two successive 30-d periods. Individuals consumed more of the alga than the prepared feed but the absorption efficiencies were the same. This probably resulted from a higher content of structural carbohydrates in the alga and a higher content of available organic matter in the feed. The amount of organic matter absorbed was the same for both foods. However, the amount of gonad production and the assimilation efficiency was greater for the prepared feed. This indicates the prepared feed is of better nutritional quality. The physiological measurements and production were greater in the first 30-d period when the temperature was 21 C. This indicates temperature will be an important consideration in aquaculture of S. intermedius.

Effect of Protein Source and Concentration on Somatic Growth of Juvenile Green Sea Urchins Strongylocentrotus droebachiensis

Abstract— An important aspect in the development of any aquaculture industry is the maximization of juvenile somatic growth (i.e., body growth) to reduce production time and increase the size of the final product. In this study, green sea urchins Strongylocentrotus clroebachiensis were fed a prepared diet from 4 December 1998 to 10 September 1999 (i.e., 280 d) in a laboratory to investigate the effect of protein source (soybean andlor fish), protein concentration (20,30,40, and 50% dry mass) and juvenile size (4-8 mm and 12-20 mm initial test diameter) on somatic growth. A natural diet of Laminwia longicrurus (i.e., kelp) was used as a reference. There was no difference in initial size among the treatments for either the smaller cohort 1 or the larger cohort 2 sea urchins (6.3 mm and 13.8 mm initial average test diameter, respectively) (P > 0.05 for all tests). After 280 d, the sea urchins fed kelp had an average size of 20.7 mm and 24.5 mm (cohort 1 and cohort 2, respectively). The final average sizes of the sea urchins fed the prepared diets, which did not relate to dietary protein concentrations andlor protein source, ranged from 13.2 mm to 16.2 mm (cohort 1) and from 20.4 mm to 22.9 mm (cohort 2), and were significantly smaller than the kelpfed sea urchins (P < 0.05 and P < 0.001, cohort 1 and cohort 2, respectively). All treatments experienced 95% survivorship or greater. Sea urchin size appears to affect growth rate when optimal conditions for growth are available (i.e., diet and water temperature). As water temperatures increased during the summer of 1999, the sea urchins in cohort 1 fed kelp had a significantly higher growth rate (0.069 dd) than the cohort 2 kelpfed sea urchins (0.052 dd) (P < 0.05). However, within each cohort, there were no significant difference in growth rate (P > 0.05) among the sea urchins fed prepared diets, suggesting sea urchins do not require high concentrations of dietary protein for superior growth, and that plant protein can substitute fish protein in sea urchin diets. Furthermore, the sea urchins fed the prepared diets had poorer test quality and larger gonad yields (13-22%) compared to the kelpfed sea urchins (4.2%) and a wild sample of sea urchins of similar size (4.0%). The results suggest that the sea urchins fed the prepared diets allocated more energy to gonad production, whereas those fed a natural diet allocated more energy toward test production. To address this gap, more research is required to identify the nutritional components required for test growth that were present in kelp, but appeared to be deficient in the prepared diets.

Importance of dehydroepiandrosterone and dehydroepiandrosterone sulfate in different diseases

Dehydroepiandrosterone and dehydroepiandrosterone-sulfate are precursors of androgens and estrogens, support the gonadal sexual steroid production. The levels of dehydroepiandrosterone and dehydroepiandrosterone-sulfate are maximal between the ages of 20 and 30 years, then start a decline of 2% per year, leaving a residual of 10-20% of the peak production by the eight decade of life. The age-associated decrease may lead to osteoporosis, deterioration of lipid-metabolism, cardiovascular diseases and second type of diabetes mellitus. Decreased levels were found in autoimmune diseases and in sexual dysfunction, too. Intracrinology describes the formation of active hormones which exert their action in the same cells where synthesis took place without release into the pericellular compartment. The high local androgen and estrogen concentration may be important in the pathomechanism of hirsutism, acne, seborrhea, breast and prostate cancer. Administration of dehydroepiandrosterone resulted in a reduction of postmenopausal osteoporosis, also the decreased symptoms in systemic lupus erythematosis, psychiatric diseases and sexual disfunction. The authors summarize the metabolism of dehydroepiandrosterone and dehydroepiandrosterone-sulfate and their role in different diseases.

The effects of season, temperature and initial gonad condition on roe enhancement of the sea urchin Evechinus chloroticus

A series of 10-week experiments were repeated during the austral autumn, winter, spring and summer to investigate the seasonal effects, independent of seasonal temperature variation, on roe development (enhancement) of Evechinus chloroticus over a 12-month period and whether this differed among urchins with different initial gonad index (GI) values. E. chloroticus collected from wild populations with high and low initial GI values were caught and held in either ambient or constant (∼ 14.7 °C) seawater temperatures. The study has shown that, given a suitable roe enhancement diet, it is possible to significantly increase the GI of urchins throughout the year and that a seasonal effect on both the final GI and increase in GI, is primarily caused by seasonal variation in temperature. There are also significant effects from other factors, such as the initial condition of the animals prior to the trial and the reproductive stage of the urchins, but these are not as significant as the effects of temperature. The results indicate that it would be possible to increase the productivity of sea urchins by capturing them in cooler water and enhancing them at a site with relatively warmer water. The initial condition (GI) of the urchins plays an important role in gonad production with animals taken in low initial GI condition producing significantly larger increases in GI throughout each of the four seasons, than those with a high initial GI value. The urchins from the two populations developed through the stages of the reproductive cycle at a similar rate despite different final GI values and rates of increase in GI in both the temperature and population treatments, indicating that the differences in gonad production are related to environmental effects rather than the reproductive stage of the urchins. The exception to this occurred in the autumn samples where lower GI values and increase in GI were found during this season compared to in other seasons for the constant temperature treatment. There is an overabundance of low GI urchins in the coastal waters of New Zealand and these animals are relatively easily found and fished on snorkel compared to high GI animals for which fishing pressure is much higher. It would appear to be more economic to fish and enhance low GI animals in New Zealand due to their relative abundance, ease of access and higher productivity during enhancement.

Human exposure to medicinal, dietary, and environmental estrogens

Estrogens are a broad class of compounds which exert many physiological effects. In addition to gonadal and peripheral endogenous estrogen production, humans can be exposed to exogenous estrogenic compounds (xenoestrogens) from medicinal, dietary and environmental sources. These compounds can exert effects similar to that of 17β-estradiol (E2) through estrogen receptor (ER)-mediated mechanisms, or via ER-independent pathways. Although estrogens are used for a number of medical purposes such as birth control and for hormone replacement therapy (HRT) in the treatment of post-menopausal symptoms, studies have found adverse health effects from their use. Increased risk of stroke and invasive breast cancer are associated with medicinal estrogen use. As an alternative to HRT, diets rich in phytoestrogens are used by many women. Even though phytoestrogen consumption is associated with reduced risk of hormone-dependent cancers and antioxidant properties, concerns about adverse effects, such as endocrine disruption, cannot be dismissed. Widespread use of chemicals with estrogenic properties in agriculture and industry has resulted in endocrine disruption in wildlife populations although the impact on human health is still in debate. In general, the ranking order of estrogen equivalent factors compared to E2 is medicinal estrogens > phytoestrogens > environmental estrogens. Serum concentrations of estrogens vary among populations depending on choice of diet, use of medicinal estrogens, and environmental exposure. Thus, determination of total exposure levels (i.e. E2 equivalent concentration) is complex and can vary greatly within a larger population.

Growth and production of sea urchin Strongylocentrotus droebachiensis in a high-Arctic fjord, and growth along a climatic gradient (64 to 77°N)

Density, growth and production of Strongylocentrotus droebachiensis were investigated in the outer parts of a high-Arctic fjord (74° 18' N, 20° 15' W) in Northeast Greenland based on a com- bination of high resolution underwater photographs of the sea floor, dredge collections, and age determinations. The average density of 1.8 ind. m -2 (ranging from 0 to 16) from 10 to 60 m water depth was correlated with depth and amount of rocky substrate. The size structure of S. droebachien- sis in summer 2004 was unimodal with highest frequencies of individuals between 20 and 50 mm in diameter. Age estimated from growth increments in the interambulacral and genital plates revealed that growth was slow and that life span reached 45 yr. Annual production was estimated at 0.307 g ash-free dry weight (AFDW) m -2 , of which gonad production made up ~67%, thereby greatly influ- encing the production-to-biomass ratio of 0.29. The annual carbon demand of S. droebachiensis was estimated at ~37 t C in the outer part of the fjord (76 km 2 ; average = 0.49 g C m -2 ), corresponding to 3.5% of the total benthic and pelagic primary production, or 2.9% of the sedimentation of organic carbon within this area. Collections of S. droebachiensis from 7 populations from sub- to high-Arctic areas revealed a decline in growth performance along a south-north climate gradient in Greenland (64 to 77° N). Difference in length of the productive open-water period explained more than 80% of the variability in growth (p < 0.01) between populations and these findings are discussed in relation to predictions of future reductions in Arctic sea ice cover.