Sexual and asexual reproduction of <Emphasis Type="Italic">Coscinasterias</Emphasis><Emphasis Type="Italic">tenuispina</Emphasis> (Echinodermata: Asteroidea) from Rio de Janeiro,Brazil

An intertidal population of the fissiparous sea star Coscinasterias tenuispina (Lamarck, 1816) was sampled over a 1 year period at Ponta de Itaipu, Niterói, Rio de Janeiro. Gonadal indices revealed an annual reproductive cycle. Spawning occurred in the late winter and early spring between August and November. Pyloric caecal indices did not show a clear annual cycle or a reciprocal relationship with gonadal indices. The population appears to be sustained only by fission, as only males were found. Fission occurred throughout the year, but was most frequent in the winter (July, August and September). Incidence of fission was correlated with the occurrence of the extremely low tides during daytime that exposes many specimens to air. Austral winter tides are low by day and high by night, while the austral summer tides are low by night and high by day. The most extreme annual deviation in seawater temperature is about 5°C. Larval recruitment seems to be negligible, since very small individuals were not found.     

Reproductive biology of <Emphasis Type="Italic">Cosmasterias lurida</Emphasis> (Echinodermata: Asteroidea) an anthropogenically influenced substratum from Golfo Nuevo,Northern Patagonia (Argentina)

The starfish Cosmasterias lurida was sampled from the pier piles of Almirante Storni in the Golfo Nuevo, northern Patagonia, from November 2001 to November 2003. In this anthropogenically modified site there is an unusually abundant food supply of mussels and large aggregations of starfishes. The reproductive cycle was studied by organ indices and histological examination of gonads. The highest gonad index (GI) values were found in the summer (February–March), followed by a drop in GI values, indicating spawning. Histological analyses indicated that gametogenesis takes place from June to January, sexual maturity occurred during the summer and spawning occurred in April. The GI and pyloric caeca index (PCI) tended to have an inverse relationship, but this was only statistically significant in males. However, biochemical analyses of the starfish indicated no transfer of nutrients between pyloric caeca and gonads in either sex. In fact, simultaneous accumulation of carbohydrates was found in the pyloric caeca and gonads of both sexes.     

Population differences in gonad and pyloric caeca cycles of the New Zealand seastarSclerasterias mollis (Echinodermata: Asteroidea)

Inshore and offshore populations ofSclerasterias mollis (Hutton, 1872) were sampled on the outer continental shelf off the Otago Peninsula, New Zealand, and their nutritional and reproductive cycles are described from 1985–1986. Histological changes in the gonads are generally typical of other asteroids. The gametogenic cycle takes 12 mo. The gonad and pyloric caeca indices in both females and males had an inverse relationship.S. mollis accumulates nutrients in the pyloric caeca during summer and early autumn. The gonads develop in the autumn and winter. Offshore seastars were much larger and had significantly higher gonad and pyloric caeca indices than inshore individuals. These differences in body sizes and organ indices arise from differences in food availability and/or population density.     

The reproductive cycle of Asterina stellifera (Möbius) (Echinodermata: Asteroidea) in the Cabo Frio region, southeastern Brazil

Reproduction of Asterina stellifera was studied in two populations from the Cabo Frio region, southeastern Brazil. One was located in an intertidal seagrass flat at Japonês Island (1994–1995); the second was on a sublittoral rocky shore at Pontal beaches (1999–2000). Reproductive cycle was studied at monthly intervals by organ indices and histological examinations of gonads. Although these two populations were studied in different habitats and at different times, the periodicity of the annual reproductive cycle was very similar for the two populations. The highest gonad index (GI) values were found in August/September (late winter), followed by a drop in GI values, indicating spawning. The GI and pyloric caeca index (PCI) tended to have an inverse relationship in both populations, but it was only statistically significant in the rocky-shore population. Gametogenesis in the two populations was described and roughly confirmed the reproductive cycles determined by GIs. Published online: 9 August 2002     

Seasonal changes in pyloric caecum and gonad indices during the annual reproductive cycle in the seastar Asterias forbesi

Seasonal changes in pyloric caecum and gonad indices were studied in a population of the seastar Asterias forbesi (Desor) from East Rockaway Inlet (Long Island, New York) during two annual cycles (1980/81, 1982/83). Pyloric caeca indices increased during fall, reached a maximum about April, and declined sharply to a minimum in mid-summer. Gonad indices increased during fall and winter and reached a maximum about May. Judging from gonad size analysis, spawning occurred in late June to early July, at bottom temperatures of 16° to 18°C. There was no long-term inverse relationship between pyloric caecum and gonad indices. Since nutrients and energy ingested during the important fall feeding period are utilized simultaneously for body growth and gonad development, it is unnecessary for the pyloric caeca to store nutrients over long periods as occurs in A. rubens and many other species. The specific caeca-gonad relationship is probably an adaptation to the extreme seasonal thermal fluctuations of the NW Atlantic, which constrain the feeding activity of A. forbesi and limit the possibility of long-term storage. In this population, most individuals grow rapidly in their first year (including first two summers) and spawn in their third summer. Few seastars survive to spawn again in their fourth summer. However, gametogenesis may take place in some individuals in their second summer. Year-to-year variability in mean size at spawning may reflect temporal variation in environmental conditions (weather, food availability) at this site.     

Coexistence and reproductive isolation of the sympatric echinoids<Emphasis Type="Italic"> Diadema savignyi</Emphasis> Michelin and<Emphasis Type="Italic"> Diadema setosum</Emphasis> (Leske) on Kenyan coral reefs

The sympatric echinoids Diadema savignyi and D. setosum coexist in shallow reef lagoons throughout East Africa. The reproductive strategies of these echinoids were studied to investigate reproductive isolation as a possible mechanism for maintaining the coexistence of these closely related species. The annual reproductive cycle and lunar periodicity were determined by gonad index measurements, histological examination of gametogenesis, and induction of spawning with injections of KCl. The peak reproductive period of D. savignyi coincided with the north-east monsoon period (when light and temperatures are high) as gonad indices were high (>8%) beginning in February and peaked at 9.7% in May. Gonad indices subsequently rapidly decreased (by 26%) in June at the beginning of the cooler south-east monsoon period. However, the presence of sperm and ova in most months of the year indicates continuous gametogenesis with reduced reproductive effort during the cooler months. The annual cycle for D. setosum showed less of a seasonal trend as gonad indices remained above 7% throughout much of the year but tended to be highest when temperatures were lower. This is the first confirmation of continuous reproduction in these two species at the equator. The reproductive patterns of both species remained consistent over 2 years of sampling. Both species exhibited a synchronized lunar spawning periodicity during the 3 months sampled, with D. setosum spawning on lunar days 8–10 and D. savignyi spawning after the full moon (lunar days 17–18). Whereas spawning in D. savignyi was very tightly synchronized, 20% of D. setosum individuals still spawned after the peak spawning period. The coexistence of these closely related species appears to be maintained by temporal reproductive isolation during the lunar spawning period reinforced by seasonal differences in reproductive effort.Communicated by O. Kinne, Oldendorf/Luhe     

Habitat influences on reproductive allocation and growth of the mummichog (<Emphasis Type="Italic">Fundulus heteroclitus</Emphasis>) in a coastal salt marsh

To determine whether life history differences can occur in salt marsh fishes that occupy different habitats within the same marsh, we compared reproductive allocation in female mummichog (Fundulus heteroclitus) inhabiting creeks and ponds of a coastal salt marsh in southern New Jersey, USA during the spring and summer of 2001 and 2002. Females were collected in phase with the lunar spawning cycle from four sites of each habitat type, and assessed for gonad-to-body-mass ratio and growth increment. Annual reproductive allocation, expressed as a percent of somatic mass, was estimated for each site and year from the gonadosomatic indices of individuals collected during each spawning period. Mummichogs from creeks showed little change in annual reproductive allocation from 2001 to 2002, whereas those inhabiting ponds showed a significant increase between these years. Seasonal reproductive patterns indicated that pond females cease spawning at least one lunar cycle earlier than creek fish. While ponds experienced considerably higher maximum summer temperatures than creeks as well as near-anoxic pre-dawn conditions, neither of these variables explained a significant amount of variation in annual reproductive allocation. In contrast, annual reproductive allocation of mummichogs in a pond correlated with its flood frequency in both years of study. Our results suggest that while the length of the spawning season differs in mummichogs inhabiting marsh creeks and ponds, annual reproductive allocation depends more upon the hydrodynamic conditions of the particular waterbody than its habitat type per se.     

Lipids and fatty acids as indicators of egg condition,larval feeding and maternal effects in Cape hakes (<Emphasis Type="Italic">Merluccius paradoxus</Emphasis> and <Emphasis Type="Italic">M. capensis</Emphasis>)

Cape hakes, Merluccius paradoxus and M. capensis, are important gadoid fish that are commercially harvested in the Benguela Current system off Namibia and South Africa. The aim of this study was to elucidate the nutritional condition and feeding preferences of their larvae. Hake eggs and larvae were sampled in austral spring of two consecutive years, 2007 and 2008, off the west coast of South Africa. They were identified to species using genetics, and total lipid content and fatty acid (FA) composition were analysed for each individual egg and larva to compare the condition of different early life stages of both hake species. Higher abundances of M. paradoxus eggs and larvae were consistently found compared to M. capensis. In both species, eggs contained wax esters (WE) and had significantly higher lipid content per dry mass than larvae. Lipid content as well as FA composition changed with the developmental stage of larvae. Quantities of essential fatty acid (EFA) increased with feeding of larvae due to dietary lipid incorporation. In 2007, yolk-sac larvae contained significantly lower total lipids than in 2008. It is argued that this was due to reduced lipid transfer by the spawning females to the eggs. These findings indicate that maternal effects are important in determining condition of hake larvae and that this may have an effect on their survival and subsequent recruitment.     

Reproduction of sympatric populations of Patiriella gunnii,P. calcar and P. exigua in New South Wales,asterinid seastars with direct development

Three asterinid seastars, Patiriella gunnii (Gray), P. calcar (Lamarck) and P. exigua (Lamarck) are sympatric in southeast Australia and form part of a series of Patiriella species endemic to Australian shores. Reproduction of co-occurring populations of P. gunnii, P. calcar and P. exigua was investigated in New South Wales from December 1988 to February 1991. Their reproductive cycles were documented by the gonad index (GI) method and by histological examination of the gonads. The annual cycle of the pyloric caecae was also documented and the relationship between the two indices was examined. Oogenesis and spermatogenesis are described in histological detail. The three species produce large yolky eggs and have direct development. Vitellogenesis and weight-gain by the ovaries results from accumulation of periodic acid Schiff (PAS +) material by the oocytes. P. gunnii and P. calcar are gonochoric and have well-defined reproductive cycles, spawning in spring and summer. There was a sharp decline in the GI of P. gunnii in December due to potentially synchronous spawning. Histological examination revealed that initiation of gamete release occurred in August. Gamete release by P. calcar also started in August, with episodic spawning through December. P. gunnii and P. calcar have coincident 3 to 4 mo breeding seasons. In general, P. exigua is protandrous with a broad size range over which sex change occurs. Some P. exigua, however are simultaneous hermaphrodites at the outset of gonad formation and become increasingly female with growth. This species has continuous gametogenesis and oviposits its eggs on the undersides of intertidal boulders, with enhanced oviposition during winter and spring. Newly metamorphosed P. exigua occupy intertidal microhabitats and were located in the field from August to October. It is suggested that increasing sea temperature during spring may serve to cue gamete release by P. gunnii and P. calcar and that enhanced oviposition of P. exigua in winter may be in response to conditions optimal for development of the egg masses at this time. The GI of male and female P. gunnii and P. calcar did not differ, while male P. exigua had a significantly lower GI than the females. Small males are characteristic of this latter species, and it is suggested that the decreased male investment in P. exigua is associated with its non-planktonic development. The gonad and pyloric caeca (PCI) indices of P. gunnii exhibited a reciprocal relationship, indicating that the transfer of nutrients from the caeca to the gonads supports gametogenesis. These indices were partly reciprocal in P. calcar. It is suggested that gonadal growth in P. calcar may be less dependent on caecal reserves than that in P. gunnii. The PCI of P. exigua maintained a similar level throughout the year and was higher than the GI. Although the Patiriella species have coincident breeding periods, temporal differences in the intensity of spawning appears to reproductively isolate them in the field.     

Changes in the biochemical composition of the pyloric caeca of female seastars,Asterias rubens,during their annual reproductive cycle

The biochemical composition of the pyloric caeca of female seastars (Asterias rubens) was studied throughout the annual reproductive cycle. The pyloric caeca index is high during the pseudo-rest stage of the ovaries and decreases gradually during ovarian growth. The pyloric caeca dry weight varies between 20 and 38% of the fresh weight. Lipids, and less prominently carbohydrates (both glycogen and other reducing sugars), seem to constitute the primary nutrient reserves for gonad growth. Proteins are also available to meet ovarian requirements during vitellogenesis. Glycogen levels are high in late autumn and winter and low at spawning time and in summer, whereas levels of the other reducing sugars are high in post-spawning months and subsequently gradually decrease during gonad development. The total lipid level is extremely variable (averaging 75 mg g^-1 organ fresh weight), peak levels of over 200 mg g^-1 being found in some individuals in summer and at spawning time. The free amino acid level is constant at about 20 mg g^-1. The protein level is rather high throughout the annual cycle, and displays only minor changes. The observed patterns of decrease in major constituents suggest a rapid release of nutrient reserves from the pyloric caeca (deposited during the summer) at the onset of vitellogenesis. Moreover, the needs of the ovaries during further development seem to be so tremendous that during the winter months the digested food may be transported to the ovaries without prior deposition in the pyloric caeca. The changes observed in the pyloric caeca are discussed and compared with those occurring simultaneously in the ovaries.     

Nestmate recognition for eggs in the honeybee (<Emphasis Type="Italic">Apis mellifera</Emphasis> L.)

Colony integrity is fundamental to social insects and is threatened by the reproduction of non-nestmates. Therefore, discrimination between eggs derived from nestmates and non-nestmates would constitute an adaptation to prevent exploitation of the entire cooperative group by unrelated individuals. The removal of nestmate and non-nestmate queen and worker-laid eggs was evaluated in honeybees using colonies of Apis mellifera capensis to test female and of A. m. scutellata to test male eggs. The data show that honeybees can distinguish between nestmate and non-nestmate eggs of both sexes. Moreover, non-nestmate female queen-laid eggs were removed significantly faster than nestmate female worker-laid eggs in A. m. capensis, indicating that nestmate recognition cues can override caste-specific ones. While the experimental manipulation accounts for 37.2% (A. m. scutellata) or 1.6% (A. m. capensis) of variance in relation to egg removal, nestmate recognition explains 33.3% for male eggs (A. m. scutellata) and 60.6% for female eggs (A. m. capensis), which is almost twice as high as the impact of caste (16.7% A. m. scutellata; 25% A. m. capensis). Our data show a stronger effect of nestmate recognition on egg removal in the honeybee, suggesting that cues other than caste-specific ones (viability/kin) can dominate egg removal behavior. In light of intraspecific social parasitism, preventing the reproduction of unrelated individuals (group selection) rather than preferring queens’ eggs (kin selection) appears to be the driving force behind the evolution of egg removal behavior in honeybees.     

Seasonal changes in biochemical composition of body walls,gonads and pyloric caeca in two populations ofSclerasterias mollis (Echinodermata: Asteroidea) during the annual reproductive cycle

Seasonal changes in biochemical composition of tissues are compared in a shallow inshore and deeper offshore population of the seastarSclerasterias mollis (Hutton, 1872) on the Otago shelf, New Zealand, from 1985 to 1986. The biochemical composition of the body wall, gonads and pyloric caeca of the two populations did not differ greatly, even though reproductive output and nutrient storage of reserves were consistently higher in the offshore population. The biochemical composition of the ovaries and testes differed. High levels of carbohydrate and lipid were maintained in the ovaries from the commencement of vitellogenesis until spawning occurred. The testes had higher ash levels during spermatogenesis. During the annual reproductive cycle, an inverse relationship in the carbohydrate levels between the ovary and the pyloric caeca suggests nutrient transfer from the pyloric caeca to the gonads during gametogenesis. Annual changes in biochemical composition indicate that the body wall is also used for nutrient storage.     

Reproductive pattern in the brooding and broadcasting sea star Pteraster militaris

Pteraster militaris (O. F. Müller, 1776) broods young in an aboral chamber and broadcasts gametes and offspring as well. The reproductive cycle of a population of P. militaris from the northwest Atlantic Ocean was examined over a 23 mo period from September 1985 to July 1987. The species is gonochoric (sex ratio 1:1), with only one incidence of hermaphroditism observed (n=261). Gonad indices were lower in females than in males, possibly an adaptation to the limited space available in the brood chamber. Body component and maturity indices, gonad histology and response to 1-methyladenine indicate that females in the population have a continuous breeding season, with a slight decrease in intensity in the spring. Males have a more pronounced decrease in the intensity of reproduction in the spring. Gonad development in males in synchronous both within and between individuals. Gonad development in females is asynchronous.     

Multi-year observations on the gametogenic ecology of the Antarctic seastar <Emphasis Type="Italic">Odontaster validus</Emphasis>

This study reports the first multi-year observations on the reproductive patterns for an Antarctic predator/scavenger, Odontaster validus (Koehler 1912). Seastars were collected monthly from a shallow site (15–20 m depth) near the British Antarctic Survey (BAS) Rothera Research Station (Adelaide Island, 67°34′S 68°08′W) from July 1997 to January 2001. Reproductive condition, oocyte size frequencies and spermatogenesis were examined in at least ten seastars each month using histological and image analysis techniques. Gonad indices (GI) and pyloric caeca indices (PI) were also examined in the same samples. Female and male GIs varied seasonally, in parallel with a reduction in the proportion of large oocytes and mature sperm in the gonad in August to mid-October following winter spawning. Despite there being remarkable consistency in the timing of spawning from year to year, differences in the reproductive condition of individuals were apparent. Patterns in the digestive tissues also varied with season, peaking in December and reaching a minimum in February in two of the three study years. This weaker annual pattern may partly reflect the varied diet of this predator/scavenger species, which is not directly dependant on the timing and magnitude of the annual phytoplankton bloom. Pooled oocyte size distributions and residual analysis suggested that oogenesis progressed over 18–24 months, with the largest of the two size classes (maximum diameter = 183 μm) being spawned annually. This pattern of oocyte growth and spawning was previously reported in the early 1960s for an O. validus population from McMurdo Sound, which lies south of Rothera by 10° latitude. The extremely catholic diet of this predator/scavenger suggests the reproductive patterns of the seastar will be less susceptible to changes in food supply compared to polar suspension feeders or deposit feeders. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Storage and depletion of lipid components in the pyloric caeca and ovaries of the seastarAsterias rubens during its annual reproductive cycle

Detailed information is presented on the changes in lipid-class profiles (polar lipids, total neutral lipids, free sterols, steryl esters, triacylglycerols, neutral ether lipids and free fatty acids), which are manifest during the annual reproductive cycle of the seastarAsterias rubens for both the storage organs (pyloric caeca) and utilizing organs (ovaries). The ovaries appear to accumulate all individual lipid components proportional to progression of vitellogenesis. Pyloric caeca, in contrast, show variable lipid-class levels, probably due to more complex processes in these organs, operating simultaneously: digestion of food, accumulation of storage lipids, mobilization of stored lipids and their release. The results are discussed in terms of current knowledge on the role of lipids in echinoderm reproduction.     

Rates of fission, somatic growth and gonadal development of a fissiparous sea star, Allostichaster insignis, in New Zealand

Seasonal changes in population structure and incidence of fission were measured in intertidal and subtidal populations of Allostichaster insignis, a fissiparous sea star. Population size structure was stable over the course of the 1-year study. Sea stars in the subtidal zone attained greater maximum size (mean arm length, R = 35 mm) than those in the intertidal population (20 mm). Fission rates were greatest among small individuals (R < 20 mm). The frequency of fission ranged from 5 to 32% with peaks in early austral summer in the intertidal zone, and in autumn and winter in the subtidal zone. Sexual reproduction occurred in early spring in sea stars larger than 12 mm. The populations were heavily biased toward males. In the laboratory, A. insignis of three size classes (small, R = 9–13 mm; medium, 19–21 mm; and large, 29–31 mm) were fed mussels ad libitum or starved (not fed macroscopic food) for ∼1 year in a 3 × 2 factorial experiment. Small and medium-sized sea stars divided throughout the experiment and the ramets of most individuals regenerated sufficiently to divide again after 6–9 months. Unfed sea stars did not undergo fission (with one exception), had a higher mortality rate, and did not grow. Small, fed sea stars grew significantly faster than medium-sized or large individuals. At the end of the experiment, the pyloric caeca index (a measure of nutritional condition) was greater in fed than in unfed animals. Gonads (only testes were observed) developed in medium-sized and large, fed sea stars. Our field and laboratory results indicate that asexual reproduction in A. insignis predominantly occurs in small, well-nourished individuals. Ramets grow gradually through repeated fission and regeneration to a size (mean length of regenerating arms, R _r ∼ 20 mm) at which they begin to switch to sexual reproduction as the dominant reproductive mode.     

Life history and production of the mysid <Emphasis Type="Italic">Orientomysis robusta</Emphasis>: high <Emphasis Type="Italic">P/B</Emphasis> ratio in a shallow warm-temperate habitat of the Sea of Japan

Although mysids play important roles in marine food chains, studies on their production are scarce, especially for warm-water species. We investigated life history and production of Orientomysis robusta in a shallow warm-temperate habitat of the Sea of Japan. Its spawning and recruitment occurred throughout the year; 19 overlapping cohorts were recognizable over an annual cycle. The summer cohorts recruited in July–September exhibited rapid growth, early maturity, small brood size, and small body size. A converse set of life history traits characterized the autumn–winter cohorts recruited in October–March. The spring cohorts recruited in April–June had intermediate characteristics of both cohorts. Life spans were 19–33, 21–48, and 69–138 days for summer, spring, and autumn–winter cohorts, respectively, and mortality rates were high for spring and summer cohorts, especially during June–August but were low for autumn–winter cohorts. Production calculated from the summation of growth increments was 488.8 mg DW m⁻² year⁻¹ with an annual P/B ratio of 21.26. The short life span seems to be responsible for such an extremely high P/B ratio. A method not requiring recognition and tracking cohorts gave similar values (534.0 mg DW m⁻² year⁻¹ and 20.49). The close agreement in production values between the two methods indicates our estimates are valid.     

Fission and its effect on population structure of Holothuria atra (Echinodermata: Holothuroidea) in Taiwan

Populations of Holothuria atra Jaeger occurring at Wanlitung and Nanwan were sampled monthly at spring tide from March 1990 to February 1992 in southern Taiwan. At Wanlitung, small individuals with evidence of fission and regeneration were abundant in shallow tidepools on the wide reef flats (density: 98±40 ( ± SD) 100 m^-2, body weight: 6 to 182 g). At Nanwan, large individuals with no evidence of fission were sparse in deep tidepools and narrow flats [density: 0.24±0.07 ( ± SD) 100 m^{- 2}, body weight: 351 to 1400 g]. At Wanlitung, fission occurred throughout the year with an average monthly fission frequency of 4.5%, peaking at 18% in September 1990 and 16% in August 1991. Fission was accomplished by revolving, twisting, and stretching of the body, resulting in two unequal fragments. The minimal weight of 3007 individuals measured during 1 yr at Wanlitung was 6 g. All ten individuals weighing 6 to 9 g ( ± SD = 6.7 ± 1.1) 100 m^{- 2} showed evidence of regeneration from fission products. Nine large individuals (>500 g) transferred from Nanwan to Wanlitung and 50 small individuals (<100 g) transferred from Wanlitung to Nanwan in February 1991 showed no evidence of fission during the following year. Fission occurs in small individuals living in shallow tidepools, suggesting that fission probably is triggered by a stressful environment resulting from solar radiation at the unusually low water level of spring tide. Fission of H. atra at Wanlitung results in a population consisting of small individuals.     

Secondary metabolite and inorganic contents in<Emphasis Type="Italic"> Cystodytes</Emphasis> sp. (Ascidiacea): temporal patterns and association with reproduction and growth

Temporal variation is one of the least known components of defence production in marine organisms. Here we examined whether there is a predictable temporal pattern in the production of chemical and structural defences by a marine invertebrate. To assess the seasonal variation in chemical defence, we measured ascididemin, the main pyridoacridine alkaloid in the blue Mediterranean morph of the ascidian Cystodytes sp. Structural defence variability was assessed on the basis of colony ash content, as it contains mainly spicules. Ascididemin concentration and the colony ash content displayed an annual cycle, reaching a minimum in spring and peaking in summer. Cross-correlation analyses with existing data on growth and reproduction suggested a significant trade-off between investment in reproduction and the other biological parameters considered (growth, inorganic content and ascididemin concentration). Our results suggest that optimization of resource allocation, probably influenced by biotic interactions and physical factors, shaped the temporal trends observed in secondary metabolite concentration and inorganic content.     

Differences in reproductive strategies of morphs of the genus Echinaster (Echinodermata: Asteroidea) from the Eastern Gulf of Mexico

Two morphs of the asteroid genus Echinaster, E. Type 1 and E. Type 2, have reciprocal annual cycles of reproduction and nutrient storage. The pyloric caeca (storage organs) reach maximal size over winter then decrease with increasing gametogenic activity in the spring. E. Type 1 broadcasts buoyant eggs in late May to early June. E. Type 2 deposits benthic eggs in late April. Lecithotrophic larval development is similar in both morphs except that larvae of E. Type 1 undergo a brief planktonic phase. E. Type 1 reaches sexual maturity at a larger size, expends a lower reproductive effort but has a greater absolute reproductive output than E. Type 2. E. Type 2 produces fewer, larger eggs and has a greater parental investment per egg. In both morphs, females have much higher gonadal lipid levels than males and expend a higher reproductive effort in terms organic matter and energy. Reproductive effort, reproductive output, nutrient storage in the pyloric caeca and body size varied between populations and between years in each morph. Egg size and parental investment per egg were constant. Within-morph variability is attributed to differences in nutritional state. Differences in reproductive strategy support the hypothesis that the morphs are separate species.