Planktonic larval duration of one hundred species of Pacific and Atlantic damselfishes (Pomacentridae)

The plankton larval duration for 100 species of Pacific and Atlantic damselfishes was estimated from daily growth increments on the otolith of juvenile fish collected at various localities between July 1987 and September 1988. For newly-settled fishes, larval duration was determined by counting the entire number of increments present on the otolith, while for older juveniles estimates were made by counting the number of increments between the center of the otolith and a mark corresponding to settlement. We document the development of otolith formation during the period when eggs are incubated on the reef and show that daily increments are only accreted after larvae hatch and enter the planktonic phase. The planktonic larval duration for damselfish is shorter and less variable, both between and within species, compared to other groups of reef fishes such as wrasses and surgeonfishes. Larval duration ranged from 12 to 39 d. Average duration between species ranged from 13.1 to 35.2 d. The time spent in the plankton was not significantly correlated with geographic distribution when evaluated among species, however, genera with confined regional distribution have a shorter mean larval life than do widely distributed genera. Size at settlement was positively correlated with time spent in the plankton among species, but a significant correlation between these variables was only evident within one of ten species. The low variance in planktonic larval duration within species indicates that most damselfish are unable to delay metamorphosis following competency. This inability to postpone settlement limits the potential for dispersal, especially when dispersal time between suitable habitats is greater than about 30 d.     

Patterns in reproductive dynamics of burrowing ghost shrimp Trypaea australiensis from small to intermediate scales

Many studies have examined latitudinal differences in reproduction of marine invertebrates, but few have measured variation at small to intermediate scales (kilometres to hundreds of kilometres), which may confound comparisons across broader geographic regions. Here, we examined variation in the reproductive biology of a little-studied species of burrowing ghost shrimp (Trypaea australiensis) at spatial scales ranging from km (between sites within estuaries) to 100s of km (among estuaries), over a 2-year period in south-eastern Australia. Sex ratios of populations were consistently biased towards females through time and space. Although reproduction started in summer months across all spatial scales, there was a pattern of earlier spawning from southern to northern estuaries. Integration of results from previous studies of T. australiensis supported a similar pattern of earlier breeding from high to low latitudes. Fecundity of shrimp increased linearly with female size, but the relationship varied inconsistently across the different spatial scales. Similarly, sizes at maturity varied from small to intermediate scales and observed patterns were not consistent with general predictions e.g. shrimp were smaller and ovigerous at smaller sizes at sites in the southern-most estuary, compared to estuaries further north. We found no differences in the sizes of embryos across the different spatial scales, but confirm that T. australiensis employs a strategy of high fecundity and small embryo size compared to other thalassinidean shrimp. Our results suggest that factors at smaller scales (e.g. food availability) may be important in affecting reproductive dynamics of T. australiensis, but further research is needed in testing hypotheses about patterns observed here. A lack of similar studies on other marine organisms remains an impediment to understanding life-history strategies and the sustainable management and conservation of populations.     

Estimating dispersal potential for marine larvae: dynamic models applied to scleractinian corals

Dispersal influences ecological dynamics, evolution, biogeography, and biodiversity conservation, but models of larval dispersal in marine organisms make simplifying assumptions that are likely to approximate poorly the temporal dynamics of larval survival and capacity for settlement. In particular, larval mortality rates are typically assumed to be constant throughout larval life; and all larvae are frequently assumed to acquire and lose competence at the same time. To improve upon these assumptions, we here develop simple models of dispersal potential that incorporate rates of mortality, and acquisition and loss of settlement competence. We fit these models to empirical competence and survival data for five scleractinian coral species, to test the models' ability to characterize empirical survival and competence patterns, and to estimate the dispersal potential implied by those patterns. The models fit the data well, incorporating qualitative features of competence and survival that traditional approaches to modeling dispersal do not, with important implications for dispersal potential. Most notably, there was high within-cohort variation in the duration of the competent period in all species, and this variation increases both self-recruitment and long-distance dispersal compared with models assuming a fixed competent period. These findings help to explain the seeming paradox of high genetic population structure, coupled with large geographic range size, observed in many coral species. More broadly, our approach offers a way to parsimoniously account for variation in competence dynamics in dispersal models, a phenomenon that our results suggest has important effects on patterns of connectivity in marine metapopulations.     

Effects of salinity and adult extract on settlement of the oligohaline barnacle Balanus subalbidus

Balanus subalbidus (Henry) has the most oligohaline distribution of three congeneric barnacles in Chesapeake Bay and tolerates prolonged exposure to fresh water. We studied larval settlement (i.e., permanent attachment and metamorphosis) of B. subaldius in the laboratory, over a 3 yr period, May 1989 to March 1992, under the following conditions: (1) across an array of salinities at 25°C in the presence and absence of settlement factor consisting of adult B. subalbidus extract; (2) in the presence of conspecific or congeneric settlement factors; and (3) cyprids which were, and were not, induced to delay metamorphosis were compared in their capacities to settle in a range of salinities. Discrepancies between salinity profiles of larval settlement in the laboratory and adult oligohaline distribution in the estuary were striking, and there was a significant interaction between salinity and settlement factor. Averaging results of four different batches of larvae, although peak settlement (87±9%) of B. subalbidus occurred at 2 ppt salinity in the presence of adult cue, substantial settlement also occurred at higher salinities: >70% at 5, 10 and 15 ppt; and 47% at 20 and 25 ppt. In addition, settlement in the absence of settlement factor was relatively high (>50%) and peaked at mid-salinity ranges (e.g. 56±10% at 15 ppt). Variation observed in settlement among larval batches reflected detailed differences in settlement between adjacent test salinities. No difference in settlement occurred between replicate aliquots of cyprids within a batch. Cyprids of B. subalbidus settled most abundantly in the presence of settlement factor extracted from conspecifics, followed in decreasing order by settlement factor extracted from B. improvisus and B. eburneus. Delay of metamorphosis produced by keeping B. subalbidus cyprids for 8 d at 5°C resulted in a decreased level of settlement, but settlement frequency patterns of delayed and non-delayed cyprids were indistinguishable relative to salinity. These results indicate that the oligohaline distribution of adult B. subalbidus is probably not determined by larval behavior at settlement. We suggest that pre-settlement behavior, resulting in larval retention in low saline waters, could be an important factor in determining distribution of this species.     

Larval biology of six species of the genus Conus (Gastropoda: Toxoglossa) in Hawaii,USA

Among the Hawaiian species in the genus Conus, larval life histories range from long-term planktotrophy to nonpelagic lecithotrophy. Prehatching developmental time, hatching size, pelagic period and total prejuvenile developmental time are all significantly correlated with egg size, while settling size is correlated with none of these larval characteristics. Therefore, larval life history patterns in the genus Conus appear to be determined by 2 sets of selective forces: the first influencing egg size, and the second stipulating settling size. As egg sizes become larger, hatching sizes and prehatching developmental time increase while pelagic periods and total prejuvenile developmental times decrease. Settling size appears to be related to water depth, but food requirements of newly metamorphosed juveniles may also be important.     

Spatial variability in habitat associations of pre- and post-settlement stages of coral reef fishes at Ishigaki Island,Japan

Successful settlement of pelagic fish larvae into benthic juvenile habitats may be enhanced by a shortened settlement period, since it limits larval exposure to predation in the new habitat. Because the spatial distribution of marine fish larvae immediately prior to settlement versus during settlement was unknown, field experiments were conducted at Ishigaki Island (Japan) using light trap sampling and underwater visual belt transect surveys to investigate the spatial distribution patterns of selected pre- and post-settlement fishes (Acanthuridae, Pomacentridae, Chaetodonidae and Lethrinidae) among four habitats (seagrass bed, coral rubble, branching coral and tabular coral). The results highlighted two patterns: patterns 1, pre- and post-settlement individuals showing a ubiquitous distribution among the four habitats (Acanthuridae) and pattern 2, pre-settlement individuals distributed in all habitats, but post-settlement individuals restricted to coral (most species of Pomacentridae and Chaetodontidae) or seagrass habitats (Lethrinidae). The first pattern minimizes the transition time between the larval pelagic stage and acquisition of a benthic reef habitat, the latter leading immediately to a juvenile lifestyle. In contrast, the second pattern is characterized by high settlement habitat selectivity by larvae and/or differential mortality immediately after settlement.     

Variation in larval life-history traits among reef fishes across the Isthmus of Panama

We tested the hypothesis that regional differences in oceanic productivity have led to the evolution of predictable patterns of regional variation in life-history traits of pelagic larvae of tropical reef fishes. To do so we compared larval traits (egg and hatchling size, larval growth rate and duration, and size at settlement) among closely related reef fishes from the Atlantic and Pacific coasts of the Isthmus of Panama. This comparison provides a control for phylogenetic effects because those regions shared a common fauna prior to the rise of the Isthmus ˜3.5 million years ago, subsequent to which each fauna evolved independently under a very different productivity regime. We measured larval traits of 12 benthic-spawning damselfishes (Pomacentridae: Abudefduf, Chromis and Stegastes) and 13 pelagic-spawning wrasses (Labridae: Bodianus, Halichoeres and Thalassoma). These included members of each genus on each side of the Isthmus and four sets of transisthmian sister species of pomacentrids. Among the pomacentrids we found consistent transisthmian differences in hatchling size, but not in other larval traits. Essentially the reverse pattern occurred among the labrids – larval growth and duration differed consistently among congeners in the two regions, but without consistent differences in hatchling size or size at settlement. Neither relationship is predicted by the regional-productivity hypothesis. Most of the differences were quite small. Stronger phylogenetic effects on larval traits (inter- and intrageneric variation within regions) occur in both families and evidently overwhelm any effect of regional variation in productivity. Reassessment of data that takes into account such phylogenetic effects questions previous conclusions about the existence of regional differences in larval traits among damselfishes in the West Pacific and the Caribbean. Received: 19 January 2000 / Accepted: 26 September 2000     

Recruitment limitation in Dungeness crab populations is driven by variation in atmospheric forcing

Ecologists have long debated the relative importance of biotic interactions vs. abiotic forces on the population dynamics of both marine and terrestrial organisms. Investigation of stock size in Dungeness crab (Cancer magister) is a classic example of this debate. We first tested the hypothesis that adult population size was set by larval success. We found that during a five-year sampling period, adult crab population size from Oregon through central California, USA, as measured by the commercial catch, varied directly with the number of terminal-stage larvae (megalopae) returning to Coos Bay, Oregon, four years earlier; adult population size was largely determined (> 90% of the variation) by success during the larval stage. We then tested whether biotic interactions or abiotic forces caused the variation in larval success. Most of the variation (> 90%) in the number of returning megalopae is explained by the timing of the spring transition, a seasonal shift in atmospheric forcing that drives ocean currents along the west coast of the United States. Early spring transitions lead to larger numbers of returning Dungeness megalopae, while in four other crab taxa, species with very different life history characteristics, early-spring transitions lead to lower numbers of returning megalopae. During the past roughly 30 years, the size of the commercial catch of Dungeness crab is significantly and negatively correlated with the date of the spring transition throughout the California Current system. Long-term variation in the date of the spring transition may explain a major crash in the Dungeness crab fishery in central California, which began in the late 1950s. The data suggest that Dungeness crab population size is determined by variation in larval success and that a significant portion of this variation is due to the timing of the spring transition, a large-scale climatic forcer.     

Settlement patterns and post-settlement survival in two Mediterranean littoral fishes: influences of early-life traits and environmental variables

We examined the relationships between daily pattern of settlement and environmental parameters during two consecutive years in two littoral fishes, Lipophrys trigloides (Blenniidae) and Chromis chromis (Pomacentridae), in the NW Mediterranean Sea. We also used individual early-life traits (pelagic larval duration, size at hatching and size at settlement) calculated from otoliths, to study the proximate causes of settlement variability and size-selective mortality after settlement. Several early-life characteristics of L. trigloides (planktonic larval duration and size at hatching), and environmental variables averaged during the whole planktonic period (e.g. water temperature, wave height, solar radiation) were related with the magnitude of settlement. In contrast, C. chromis showed no significant relationships between early-life traits and the magnitude of settlement, and a weak relationship between settlement magnitude and environmental variables. Furthermore, juvenile survivors showed larger size at hatching than settlers, indicating that size at hatching affected the juvenile survival of the two species. These results suggest that survival was linked largely to conditions at hatching for both species.     

Effects of Urbanization on Occupancy of Stream Salamanders

Abstract: Urban development is the most common form of land conversion in the United States. Using a before–after control‐impact study design, we investigated the effects of urbanization on larval and adult stages of southern two‐lined salamanders (Eurycea cirrigera) and northern dusky salamanders (Desmognathus fuscus). Over 5 years, we estimated changes in occupancy and probabilities of colonization and survival in 13 stream catchments after urbanization and in 17 catchments that were not urbanized. We also examined effects of proportion of urbanized area in a catchment and distance of the salamander population to the nearest stream on probabilities of colonization and survival. Before urbanization, adult and larval stages of the two salamander species occupied nearly all surveyed streams, with occupancy estimates ranging from 1.0 to 0.78. Four years after urbanization mean occupancy of larval and adult two‐lined salamanders had decreased from 0.87 and 0.78 to 0.57 and 0.39, respectively. Estimates of mean occupancy of larval northern dusky salamanders decreased from 1.0 to 0.57 in urban streams 4 years after urbanization; however, adult northern dusky salamander occupancy remained close to 1.0 in urban streams over 5 years. Occupancy estimates in control streams were similar for each species and stage over 5 years. Urbanization was associated with decreases in survival probabilities of adult and larval two‐lined salamanders and decreases in colonization probabilities of larval dusky salamanders. Nevertheless, proportion of impervious surface and distance to nearest stream had little effect on probabilities of survival and colonization. Our results imply that in the evaluation of the effects of urbanization on species, such as amphibians, with complex life cycles, consideration of the effects of urbanization on both adult and larval stages is required.     

Planktonic larval duration and settlement marks on the otoliths of Mediterranean littoral fishes

The planktonic larval duration (PLD) was estimated for 42 species of littoral fishes from the north-western Mediterranean Sea. Daily increments and settlement marks on the otoliths (sagittae or lapilli) of new settlers and post-settlers were used to determine the larval stage duration. We also used PLD in the new settlers of some species to confirm the accuracy of the settlement marks in post-settlers. The duration of the planktonic larval stage ranges from 9 days in Symphodus ocellatus to 55 days in Xyrichtis novacula and 71 days in Lipophrys trigloides. Species in the same family did not display any clear tendency toward having similar PLDs. On the other hand, larval duration tended to be similar within a genus, with the exception of Lipophrys. Among conspecifics, the time spent in the plankton usually varied only by 2-7 days, except in Aidablennius sphynx, Lipophrys trigloides, Coris julis and Thalassoma pavo. No clear patterns were discernible in genera, with some species that settled in winter and other species that settled in summer, although we observed a certain tendency of individuals of closely related species (e.g. family Sparidae) to have a shorter larval duration in the warmer part of the year than in the colder part of the year. Settlement marks have been observed on the otoliths of all the species studied, and the PLDs in new settlers are an appropriate means of validating settlement marks. A rapid decrease in increment width over settlement (type Ia) is the most common type of mark (66.7% of the total species studied).     

Life history strategy of a southern European population of brown shrimp (Crangon crangon L.): evidence for latitudinal changes in growth phenology and population dynamics

This study provides a comprehensive examination of the life cycle dynamics of the brown shrimp (Crangon crangon L.) in the Mondego estuary, Portugal, a habitat located near the southern edge of the range of this species in European waters. The phenology of all life stages was documented (from the occurrence of ovigerous females, developing embryos, planktonic larvae and benthic post-larvae), and migration patterns of larvae into and out of the estuary were examined. Temperature-dependent functions of egg and larval development were combined with data on field abundance to predict the timing and magnitude of occurrence of larvae and recruits. Compared to brown shrimp at higher latitudes, southern conspecifics grow slower, mature earlier and have smaller brood sizes, and larvae have a more protracted settlement period. The Mondego estuary, besides acting as nursery area, is a dynamic platform for C. crangon to use in different stages, sizes and seasons.     

Larval period and its influence on post-larval life history: comparison of lecithotrophy and facultative planktotrophy in the aeolid nudibranch Phestilla sibogae

The variable duration of the pelagic phase of metamorphically competent larvae of benthic marine invertebrates is set by an interaction between environmental factors and larval traits that together influence the chance that a larva will encounter and respond to a suitable settlement site. In the Hawaiian aeolid nudibranch Phestilla sibogae Bergh, an extended competent larval phase resulted in a cascade of negative effects on larval and post-larval life-history traits. When raised as fed (i.e., facultatively planktotrophic) larvae, an extended larval period resulted in lower larval survival, slightly lower metamorphic success, and delayed reproduction. When raised as unfed (i.e., lecithotrophic) larvae, an extended larval period resulted in lower larval and post-larval weights, survival, metamorphic success, and reproductive output, and also resulted in a longer juvenile period and delayed reproduction. The chance nature of locating a settlement site generally spreads these negative effects over all larvae of a cohort, and so balances the relative fitness of the genetic lineages within a population.     

Spatially stochastic settlement and the coexistence of benthic marine animals

For sessile organisms, dispersal and recruitment are typically spatially stochastic, but there is little understanding of how this variability scales up to influence processes such as competitive coexistence. Here we argue that coexistence of benthic marine animals is enhanced by stochastic differences between species in the spatial distribution of larval settlement. Differentiation of settlement distributions among competitors results in intraspecifically aggregated settlement, which can reduce overall interspecific competition and increase overall intraspecific competition. We test for the components of this mechanism using a pair of subtidal invertebrates, and we find that the mean interspecific effect of the dominant competitor is substantially reduced by natural settlement variability. Using a simulation parameterized with experimental data, we find that variable settlement could play an important role in long-term coexistence between these species. This mechanism may apply broadly to benthic marine communities, which can be highly diverse and typically exhibit large settlement fluctuation over a range of scales.     

Waterborne chemical compounds in tropical macroalgae: positive and negative cues for larval settlement

Settlement sites of marine invertebrate larvae are frequently influenced by positive or negative cues, many of which are chemical in nature. Following from the observation that many shallow-water, Hawai'ian marine macroalgae are free of fouling by sessile invertebrates, we predicted that the algae are chemically protected and dependent on either surface-bound or continuously released soluble compounds to deter settling invertebrate larvae. To address the importance of waterborne algal compounds, we experimentally determined whether larvae of two of Hawai'i's dominant hard-surface fouling organisms, the polychaete tube worm Hydroides elegans and the bryozoan Bugula neritina, would settle in the presence of waters conditioned by 12 species of common Hawai'ian macroalgae (representing the Phaeophyta, Chlorophyta, Rhodophyta and Cyanophyta). The results included a full spectrum of biological responses by each larval species to waterborne algal compounds. Larval responses to conditioned water were consistent for each algal species, but the outcomes were not predictable based on the taxonomic relationships of the algae. For example, among the species of Phaeophyta examined, different conditioned waters were: (1) toxic, (2) inhibited settlement, (3) simulated settlement, or (4) had no effect, compared to larvae in control dishes containing filtered seawater. Additionally, larval responses to aged (24 h) conditioned waters could not be predicted from the results of assays run with conditioned waters utilized immediately after preparation. Finally, settlement by larvae of one species did not predict outcomes of tests for the other species. Four of 12 shallow-reef Hawai'ian macroalgae tested released compounds into surrounding waters that immediately killed or inhibited settlement by both H. elegans and B. neritina (toxic: Dictyota sandvicensis; inhibitory: Halimeda discoidea, Sphacelaria tribuloides, Ulva reticulata); the remaining 8 algal species prevented settlement by one of these fouling organisms but for the other had no effect or, in some cases, even stimulated settlement     

Mitochondrial DNA analyses of the red rock lobsterJasus edwardsii supports an apparent absence of population subdivision throughout Australasia

Nucleotide sequence polymorphism in the mitochondrial genomes of 132 adult lobsters (Jasus edwardsil) collected from widespread locales across southern Australia and from New Zealand (April 1989 to June 1990) was assayed, using six restriction endonucleases, to test the hypothesis of a lack of genetic subdivision in a marine species with a long-lived planktonic larva. The mean amount of mtDNA diversity among the 132 mitochondrial genomes was 0.77%. Phenetic clustering and gene-diversity analyses, as well as pairwise comparison of the genetics of specimens from each, or grouped, locales did not detect the presence of genetic subdivision across approx 4600 km of Southern Ocean habitats. The inability of this study to detect population subdivision does not preclude fortutitous, active or habitat-specific larval settlement from producing and maintaining hidden groupings. If genetic homogeneity is maintained in this species by larval dispersal in ocean currents flowing to the east, then westerly populations may deserve special conservation status.     

Metamorphosis and developmental evolution in <Emphasis Type="Italic">Ophionereis</Emphasis> (Echinodermata: Ophiuroidea)

The brittle star Ophionereis schayeri has abbreviated non-feeding development through a reduced ophiopluteus and a vitellaria larva. The metamorphic changes involved with development from a bilateral larva to a radial juvenile were examined in detail. The reduced ophiopluteus has a continuous ciliated band that breaks up into discontinuous ciliary ridges at the vitellaria stage. As the vitellaria develops, the juvenile rudiment forms in the mid-ventral region. The rudiment then undergoes a morphogenetic movement to the left of the larval anterior/posterior axis. This results in a dramatic transformation from bilateral to radial symmetry and is accompanied by development of juvenile structures and settlement, 6–7 days after fertilisation. Ophiuroid development through one larval stage, the ophiopluteus, is termed Type I; whereas development through two larval stages, the ophiopluteus and vitellaria, is termed Type II. We examined the evolutionary changes in the expression of Type II development in Ophionereis by comparing the ontogeny of six species with a range of larval forms. O. fasciata has the ancestral-like planktotrophic ophiopluteus. Vestigial pluteal structures in the larvae of O. schayeri, provide a link between ophiopluteal and vitellarial forms during evolution of non-feeding development. The diversity of larval forms in Ophionereis indicates that evolution of non-feeding development through a vitellaria (Type II) may have involved an increase in egg size, reduction of pluteal structures and shortening of the time to metamorphosis. Assessment of the phylogenetic significance of Types I and II development awaits additional comparative data on the metamorphic stages of other ophiuroid genera.Communicated by G.F. Humphrey, Sydney     

Larval settlement in the serpulid polychaete Hydroides elegans in response to bacterial films: an investigation of the nature of putative larval settlement cue

Larval settlement in the marine polychaete Hydroides elegans (Haswell) is induced by certain bacteria in marine biofilms. The exact nature of the settlement cue that larvae of H. elegans receive from these bacteria remains unknown. In this study, we revealed some properties of the bacterially derived larval settlement cue by investigating the larval settlement inductive activity of two bacterial strains after various treatments. These two bacterial strains, Roseobacter sp. and an α-subclass Proteobacteria, are highly inductive to larval settlement of H. elegans. The larvae responded similarly to Roseobacter and Proteobacteria in all the larval settlement bioassays, suggesting that the larval settlement-inducing substances produced by these bacteria may share common characteristics. First of all, the larvae did not settle in the seawater conditioned by the bacteria attached as a film or by the bacteria that were freely suspended in seawater. The results suggest that the putative larval settlement cue is not released into seawater and, therefore, should be associated with the surface of the bacteria. Secondly, formaldehyde treatment entirely eliminated the larval settlement induction activity of the bacterial films, and streptomycin treatment reduced the percentage of larval settlement on the bacterial films in a concentration-dependent manner. Since both treatments can kill bacteria with little damage to the surface chemistry of bacterial cells, the decline in larval settlement is suggested be due to a reduction of the viable bacterial population in the bacterial films. In fact, the reduction of larval settlement in the streptomycin treatments coincided with the decrease in viable bacterial populations in broth cultures containing respective concentrations of streptomycin. These results suggest that the viability of Roseobacter and Proteobacteria is important to their settlement induction effect. Since the larval settlement induction activity of the bacterial strains appears to correlate with their viability, we suggest that the putative larval settlement cue is derived from a metabolic pathway in the bacteria and that the cue is exported to and concentrated at the extracellular polymer matrix of the bacterial cell, at which the larvae establish contact with the bacteria. The larval settlement cue may be highly susceptible to degradation so that a metabolically active bacterial film is needed to maintain the putative cue at a concentration that surpasses the threshold for induction of larval settlement. Received: 14 October 1998 / Accepted: 5 September 2000     

Changes in biochemical and fatty acid composition of the razor clam <Emphasis Type="Italic">Solen marginatus</Emphasis> (Solenidae: Bivalvia) during larval development

Aquaculture studies have revealed that polyunsaturated fatty acids are critical for maintaining substantial growth, survival and reproductive rates, and high food conversion efficiencies for a wide variety of marine and freshwater organisms. The aim of this study was to investigate the gross biochemical and fatty acid composition of both neutral and polar lipid compartments of the razor clam Solen marginatus throughout embryonic and larval development. High levels of stored reserves in S. marginatus eggs allow a short larval development, lasting only 8 days. The energy required for embryogenesis was obtained from stored proteins. During larval development from D-shaped veliger until settlement, protein, lipid, and carbohydrate reserves were indistinctly stored for metamorphosis. Although total lipids increased, fatty acids in both neutral and polar lipids decreased during embryonic development. The depots allow a short larval development in which settlement is reached with lower amounts of stored neutral and polar lipids than the contents found in the oocytes. Non-methylene-interrupted dienoic fatty acid levels were similar to those of some polyunsaturated fatty acids, with increasing percentages at the onset of metamorphosis. This study indicates that S. marginatus exhibits a different pattern in the use of gross biochemical and fatty acid reserves during larval development compared to other razor clam and bivalve species, mainly due to the large size of its eggs and the short larval development stage reported in this species.