Consecutive Spawning Research Articles

Relative importance of phenotypic plasticity and carryover effects in response to small salinity shifts during oyster aquaculture production

Variability of water conditions in coastal environments could affect oyster aquaculture production through three main environmental-tolerance mechanisms: phenotypic plasticity, within-generation carryover effects, and selective mortality. Aquaculture production of eastern oyster, Crassostrea virginica, larvae occurs on weekly timescales in Virginia, with variations in salinity experienced by subsequent larval cohorts. The present study examined the relative importance of within-generation carryover effects – phenotypic changes during a previous life stage that impact a later stage – and phenotypic plasticity in shaping the performance of juvenile oysters after an experience of small differences in salinity (< 2 salinity units) during the larval stage. Genetic diversity was also assessed to rule out large shifts in allele frequencies, or loss of diversity, that would suggest observed effects were the result of selective mortality rather than carryover effects or phenotypic plasticity. Larval oysters were reared through settlement and metamorphosis under two salinities (thirteen and fifteen) that represent small differences between consecutive spawns in a hatchery. Juveniles were then raised in situ in two Virginia tributaries of the lower Chesapeake Bay, the York and Rappahannock rivers. Oyster production occurs within these two tributaries under distinct salinity conditions, with the Rappahannock tending to be of lower salinity. Metrics of survival, growth, oxidative stress, and condition index were compared to assess phenotypic plasticity and within-generation carryover effects. Juvenile oyster survival and physiology correlated with in situ environmental conditions rather than previous larval salinity experience. Specifically, juvenile oysters raised in the Rappahannock River had greater survival (13%), shell length (14%), condition index (38%), and dry tissue weight (78%) than those raised in the York River, regardless of larval salinity. Rappahannock River oysters also had 20% lower total antioxidant capacity than York River oysters. Genetic diversity remained high with no large shifts in allelic frequencies that would suggest non-random loss of alleles attributable to selection. Our results suggest that small salinity differences experienced in shellfish hatcheries 48 h after fertilization likely do not impact juvenile oyster performance during grow-out; rather, phenotypic plasticity likely underpins juvenile oyster performance during the transition from hatchery to farms. The importance of phenotypic plasticity presents another reason why farm site selection is critical to the performance and success of aquaculture product. Future studies are needed to further identify whether larval responses to salinity conditions are dependent on additional environmentally relevant conditions like temperature or the timing of exposure post-fertilization to better understand the relative importance of phenotypic plasticity, within-generation carryover effects, and selective mortality within oyster aquaculture.

Seasonal habitat utilization provides evidence for site fidelity during both spawn and non-spawning seasons in Lake Ontario cisco Coregonus artedi

The Lake Ontario cisco Coregonus artedi population declined in the 20th century, and restoration of this species is a management objective. Management tools to restore cisco are limited because little is known about cisco spawning behavior and habitat use. We tagged 76 cisco from a remnant population in Chaumont Bay, Lake Ontario with acoustic transmitters and characterized seasonal habitat use from 2016 to 2021. We also used fine-scale acoustic telemetry, coregonine egg collections, and trap net catches to better understand cisco spawning behaviors related to spawn timing and site selection. Network analysis and Bayesian standard ellipse area indicated that cisco utilization of lake regions and bathythermal niche space varied by season. During spawning season, male cisco concentrated in Chaumont Bay over shallow (∼3 m) rocky shoals where cisco egg deposition was the greatest. Spawning site fidelity to Chaumont Bay was observed for all male cisco surviving to successive years (n = 23). Acoustic-tagged females did not survive consecutive spawning seasons, but trap net catches indicated females were less abundant and occupied spawning areas for less time than males. Post spawn, some individual male cisco (n = 5/23) had differential, yet consistent, annual migrations to separate regions of Lake Ontario, suggesting fidelity to feeding sites. Our results reveal seasonal habitats used by male cisco and, importantly, caution that environmental changes to a single spawning site could negatively affect the remnant Chaumont Bay cisco population. Specialized conservation efforts may be necessary when cisco spawning aggregations have diverse post-spawn migratory behaviors but a central spawning ground.

Impacts of sublethal concentrations of 17 α-ethinylestradiol (EE2) on growth, reproductive performance, and survival in red cherry shrimp Neocaridina davidi (Crustacea, Atyidae) during consecutive spawnings

This study was conducted for the first time to investigate the long-term impacts of sublethal concentrations of 17 α-ethinylestradiol (EE2) on growth, survival, and reproductive performances in a model shrimp, the red cherry (Neocaridina davidi), females during five successive spawning steps for 7.5 months. Females were distributed in eighteen aquariums and continuously exposed to EE2 at six nominal concentrations of 0 (control), 0.02, 0.2, 2, 20, and 200 μg/L. Growth indices increased up to 0.2 μg/L and then sharply declined up to 200 μg/L. Most reproductive indices significantly decreased at levels > 0.02–0.2 μg/L with increasing EE2 levels. The highest absolute, relative, and actual fecundity values were recorded in the control, with the lowest value at 200 μg/L. With increasing EE2 levels, mean egg volume showed an increasing trend from the third spawning event onwards. Except for the time required to reach the first spawning, inter-spawning intervals considerably decreased with increasing EE2 levels at > 0.2 μg/L, especially from the third spawning stage onwards. Survival of exposed females significantly decreased with increasing EE2 levels. Unlike the body size, the juvenile's survival rates in all exposed treatments were considerably lower than the control. Females at concentrations 0.02–0.2 μg/L gained more body weight and length but produced fewer eggs with lower hatching percentages during five consecutive spawns. The results suggest that EE2 depending on the concentrations can cause unbalanced growth, reduce reproductive performances, especially from the third stage of spawning onwards, and reduce survival rates in brooders and subsequent offspring. In terms of growth, survival, and reproductive indices over successive spawns in ecotoxicology studies, the concentrations of 0.02–0.2 μg/L can be considered as chronic levels, but higher levels may have detrimental effects.

Individual repeatability in the timing of river entry indicates the strong influence of photoperiod in the spawning migrations of iteroparous twaite shad Alosa fallax

The timing of entry into freshwater by mature anadromous fishes is an important component of their migration phenology. In iteroparous anadromous species, identifying the migration cues that influence the timing of entry into freshwater, and annual variability in these timings, is important in assessing the extent of individual repeatability. Here, passive acoustic telemetry tracked 71 twaite shad Alosa fallax (‘shad’) returning to the River Severn’s upper estuary over successive spawning seasons, providing individual information on river entry timing and the associated migration cues. The timing of shad returning to the river (defined as their first detection on an acoustic receiver in the upper estuary) was consistent between years and strongly predicted by photoperiod (as increasing day length), whereas water temperatures and flow rates were weak predictors and highly variable between years. Timings of river entry of individual shad were also consistent across consecutive spawning migrations, indicating high individual repeatability. The application of acoustic telemetry in this study thus revealed high repeatability in the timing of annual spawning migrations, which were cued mainly by increasing day length and that, being seasonally predictable, should ensure entry into freshwater with sufficient time to arrive in spawning areas when in-river environmental conditions are favourable.

Feeding after spawning and energy balance at spawning are associated with repeat spawning interval in steelhead trout

Consecutive and skip repeat spawning (1- or ≥2-year spawning interval) life histories commonly occur in seasonally breeding iteroparous fishes. Spawning interval variation is driven by energetic status and impacts fisheries management. In salmonids, energetic status (either absolute level of energy reserves or the rate of change of energy reserves, i.e., energy balance) is thought to determine reproductive trajectory during a critical period ∼1 year prior to initial spawning. However, information on repeat spawners is lacking. To examine the timing and the aspects of energetic status that regulate repeat spawning interval, female steelhead trout (Oncorhynchus mykiss) were fasted for 10 weeks after spawning and then fed ad libitum and compared to ad libitum fed controls. Plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels were measured to assess long-term energy balance. Plasma estradiol levels showed that some fish in both groups initiated a consecutive spawning cycle. In fasted fish, GH was lower at spawning in consecutive versus skip spawners. In consecutive spawners, GH was higher at spawning in fed versus fasted fish. These results suggest that fish with a less negative energy balance at spawning initiated reproductive development in the absence of feeding, but that feeding during the post-spawning period enabled initiation of reproduction in some fish with a more negative energy balance at spawning. Thus, both energy balance at spawning and feeding after spawning regulated reproductive schedules. These results show that the critical period model of salmonid maturation applies to regulation of repeat spawning, and that the reproductive decision window extends into the first 10 weeks after spawning.

First tagging data on large Atlantic bluefin tuna returning to Nordic waters suggest repeated behaviour and skipped spawning

Atlantic bluefin tuna (Thunnus thynnus; ABFT) is one of the most iconic fish species in the world. Recently, after being very rare for more than half a century, large bluefin tunas have returned to Nordic waters in late summer and autumn, marking the return of the largest predatory fish in Nordic waters. By tagging 18 bluefin tunas with electronic tags (pop-up satellite archival tags), we show that bluefin tuna observed in Nordic waters undertake different migration routes, with individuals migrating into the western Atlantic Ocean, while others stay exclusively in the eastern Atlantic and enter the Mediterranean Sea to spawn. We additionally present evidence of possible skipped spawning inferred from behavioural analyses. In Nordic waters, ABFT are primarily using the upper water column, likely reflecting feeding activity. The results support the hypothesis that ABFT migrating to Nordic waters return to the same general feeding area within the region on an annual basis. These observations may have important implications for management because (1) tunas that come into Nordic waters might represent only a few year classes (as evidenced by a narrow size range), and thus may be particularly vulnerable to area-specific exploitation, and (2) challenge the assumption of consecutive spawning in adult Atlantic bluefin tuna, as used in current stock assessment models. Without careful management and limited exploitation of this part of the ABFT population, the species’ return to Nordic waters could be short-lived.

Hatchery-produced sandfish (Holothuria scabra) show altered genetic diversity in New Caledonia

Facing an alarming continuing decline of wild sea cucumber resources, management strategies were developed over the past three decades to sustainably promote development, maintenance, or regeneration of wild sea cucumber fisheries. In New Caledonia (South Pacific), dedicated management efforts via restocking and sea ranching programs were implemented to cope with the overharvesting of the sandfish Holothuria scabra and the recent loss of known populations. In order to investigate genetic implications of a major H. scabra restocking program, we assessed the genetic diversity and structure of wild stocks and hatchery-produced sandfish and compared the genetic outcomes of consecutive spawning and juvenile production events. For this, 1,358 sandfish collected at four sites along the northwestern coasts of New Caledonia, as well as during five different restocking events in the Tiabet Bay, were genotyped using nine polymorphic microsatellite markers. We found that wild H. scabra populations from the northwestern coast of New Caledonia likely belonged to one panmictic population with high level of gene flow observed along the study scale. Further, this panmictic population displayed an effective size of breeders large enough to ensure the feasibility of appropriate breeding programs for restocking. In contrast, hatchery-produced samples did suffer from an important reduction in the effective population size: the effective population sizes were so small that genetic drift was detectable over one generation, with the presence of inbred individuals, as well as more related dyads than in wild populations. All these results suggest that dedicated efforts in hatcheries are further needed to maintain genetic diversity of hatchery-produced individuals in order to unbalance any negative impact during this artificial selection.

High rates of consecutive spawning and precise homing in Sakhalin taimen (Parahucho perryi)

The frequency of reproduction and homing success are crucial in determining the lifetime reproductive fitness of iteroparous salmonids. We examined consecutive spawning and homing by Sakhalin taimen (Parahucho perryi), one of the least-studied iteroparous salmonids. The average consecutive return rate was 69.5%, the highest ever reported for an iteroparous salmonid. The consecutive return rates were highest for large spawners, females, and individuals with active inter-tributary movements in the preceding year. We estimated tributary-scale repeat homing rates to be 50–87%, which was significantly higher than expected by chance alone. The repeat homing rates were higher for spawners that entered tributaries with more abundant spawners in the preceding year, which is consistent with the pheromone hypothesis because the abundance of spawners in a tributary is expected to correlate to the concentration of chemical homing cues emanating from offspring in the following year. These extremely high consecutive return and homing rates likely facilitated local adaptation over evolutionary time scales and have contributed to population stability in this river system. These same traits, however, may impede species recovery following habitat restoration efforts within the species historic range (e.g. dam barrier removal or improved passage) due to their limited rate of dispersal.

Monitoring of common sole Solea solea (L) captive broodstock from Northern Adriatic Sea over consecutive spawning seasons

The high nutritional quality of common sole Solea solea increases its value for the fishery industry and for the aquaculture sector. To ensure the expansion of its production, it is necessary to implement farming and broodstock management technique to produce high quality eggs and larvae. This work summarizes eight years of study on reproductive performances, growth and parental contribution of a common sole broodstock from the Mediterranean-North Adriatic Sea. The broodstock (11 females and 13 males) reached the peak of fecundity after 5/6 years of captivity, with a production of 296.48 and 376.54 × 103 of total eggs kg−1 female with a fertilization rate of 31.6 ± 18.3 and 41.9 ± 23.8 %, respectively. Results shows that variations in temperature cycles are pivotal for a successful breeding season, and body condition during the first 3 years of captivity was the most important parameter positively correlated to parental contribution for both males and females. Parental contribution was assessed by eight species-specific microsatellite loci during the first 3 years of reproduction. Although the two sexes displayed different temporal trends, parentage assessment demonstrated an overall increase in the number of active breeders. However, only 13 couples out of 50 produced the 70.4 % of the larvae in year 5, confirming the same reproduction behavioural pattern in Mediterranean common sole than that observed both in Senegalese sole and in common sole of Atlantic origin.This work provides valuable data needed to understand the mechanisms behind the maturation characteristics of this species and support future strategy for the establishment and management of Mediterranean common sole aquaculture.

Effects of Physiological Condition on Aspects of Repeat Spawning in Female Steelhead Reconditioned in Captivity

AbstractPhysiological condition (hereafter shortened to “condition”) influences survival, spawning schedules, and reproductive effort in salmonids. In iteroparous females, the effects of first spawning on condition could result in trade‐offs with future reproduction, mediated by postspawning survival, repeat spawning schedule (i.e., consecutive or skip spawning), or reproductive effort. However, which aspects of condition affect these outcomes and when they are sensitive to condition are not well understood. These issues were examined in highly energy‐depleted hatchery‐origin female summer steelhead Oncorhynchus mykiss that were undergoing postspawning reconditioning in captivity. Measures of condition and reproductive characteristics (i.e., fecundity, egg size, and total egg mass [TEM]) at first spawning were examined for their effects on postspawning survival and future spawning schedules, and condition was tracked during reconditioning to examine effects on reproductive characteristics at repeat spawning. The levels of plasma osmolality and triglycerides measured at first spawning were positively correlated with survival probability, suggesting that survival depends on the ability to maintain homeostasis and access stored energy. Surprisingly, size‐standardized TEM measured at first spawning was positively correlated with the probability of consecutive spawning, providing no support for the hypothesized trade‐off between current and future reproduction. This finding instead suggests that both first‐spawning reproductive effort and consecutive spawning may be influenced by condition at earlier points. Plasma triglycerides and growth rates at sampling points 10–20 weeks after first spawning were strongly correlated with size‐standardized egg size and TEM at consecutive spawning, suggesting that reproductive effort and its allocation to egg size and fecundity depend on energetic status during early oogenesis. These results indicate that condition influences survival, repeat spawning schedules, and reproductive characteristics in female steelhead up to a year or more before repeat spawning. If more broadly applicable, these relationships could provide insight into the mechanisms that link environmental conditions with reproductive characteristics in salmonids and other species.

Elevated plasma triglycerides and growth rate are early indicators of reproductive status in post-spawning female steelhead trout (Oncorhynchus mykiss).

Many iteroparous fishes spawn after skipping one or more yearly cycles, which impacts recruitment estimates used for fisheries management and conservation. The physiological mechanisms underlying the development of consecutive and skip spawning life histories in fishes are not well understood. In salmonids, lipid energy reserves and/or growth are thought to regulate the initiation of reproductive maturation during a critical period ~1year prior to spawning. The fasting spawning migration of summer-run steelhead trout (Oncorhynchus mykiss) results in significant depletion of energy reserves during the proposed critical period for repeat spawning. To determine whether and when lipid energy reserves and growth influence repeat spawning, measures of lipid energy reserves, growth rate and reproductive development were tracked in female steelhead trout from first to second spawning as a consecutive or skip spawner in captivity. Plasma triglyceride (TG) levels and growth rate were elevated by 10weeks after spawning in reproductive (i.e. consecutive spawning) versus non-reproductive (i.e. skip spawning) individuals. Muscle lipid (ML) levels, condition factor and plasma estradiol levels increased at later time points. The early differences in plasma TG levels and increases in growth rate are attributable to differential rates of feeding and assimilation between the groups following spawning. A year after spawning, plasma TG levels, MLs and growth rate decreased in consecutive spawners, attributable to transfer of lipid reserves into the ovary. During the year prior to second spawning, energy reserves and plasma estradiol levels were higher in reproductive skip spawners versus consecutive spawners, reflecting the energy deficit after first spawning. These results suggest that the decision to initiate ovarian recrudescence occurs by 10weeks after first spawning and are consistent with the differences in energy reserves acquired following spawning being a consequence of that decision. This information will increase the success of conservation projects reconditioning post-spawning summer-run steelhead trout.

Modulation of reproductive exhaustion usingUlva clathratain Pacific white shrimpLitopenaeus vannamei(Boone, 1931) broodstock during commercial maturation

Ulva clathrata meal (2%) was supplemented in a fresh maturation diet for Litopenaeus vannamei broodstock in a commercial larval facility and its effects on reproductive performance, histology and histochemistry of gonad, and biochemical composition of gonad, hepatopancreas, and muscle were analysed. Females that were given Ulva in the diet had reduced mortality compared to controls, with no differences in males. Females fed Ulva also had bigger oocytes but only those in late vitellogenesis (+7%, p < 0.01) and postvitellogenesis (+15%, p < 0.01); they also had a higher proportion of late vitellogenic oocytes in maturation stage II, and a bigger area occupied by cortical rods. No significant differences were found for the proportion of previtellogenic or early vitellogenic oocytes per maturation stage or as a result of Ulva. Females fed Ulva had higher levels of lipids in ovary (+35%, p < 0.05), with no significant differences in biochemical reserves in hepatopancreas or muscle. The total number of eggs (+5%, p < 0.01), nauplii per spawn (+18%, p < 0.01), and hatching rate (+13%, p < 0.01) during the productive cycle were higher for Ulva fed shrimp. Individual follow-up of marked females during the productive cycle showed a decreased reproductive exhaustion in females fed Ulva over consecutive spawns. Apparently, U. clathrata stimulates advanced vitellogenesis by improving lipid accumulation in gonads, and this in turn increases reproductive performance: inclusion of this algae in shrimp diet could be used to decrease reproductive exhaustion during production.

Effect of multiple spawning on female reproductive output and offspring quality in a freshwater caridean shrimp with direct development

AbstractThe decline with age in components of fitness is variable among different taxa and includes changes in fertility and brood quality. In this study, we selected individuals of Neocaridina davidi, a freshwater shrimp with direct development, to analyze juvenile quality and female reproductive performance over successive spawnings, both of which are correlated with female age. Given the high costs of reproduction in species with direct development, we hypothesized that female reproductive performance and juvenile quality decrease in later spawns. Two experiments were performed. In Experiment 1, we evaluated the reproductive performance of females of N. davidi and the quality of juveniles (through a food restriction test) over the first six successive spawnings. In Experiment 2, we analyzed the lipid and protein contents in juveniles from the third, fourth, and fifth spawns, after feeding them daily or starving them for 8 d or 12 d after hatching. Female mortality was observed throughout Experiment 1, along with a decrease in the proportion of ovigerous females over successive spawns. However, the interval between spawnings and the number and size of newly hatched juveniles were similar among spawns. Moreover, females that spawned many times had a reproductive efficiency similar to those that spawned few times, as evidenced by a similar percentage of broods successfully hatched and a similar percentage of broods with more than 28 juveniles among all spawns. Overall, these results may indicate a partial effect of multiple spawning on female reproductive performance. Growth, survival, and biochemical composition of food‐restricted juveniles showed similar or even higher values in later spawns as compared to the first spawns. This is, to our knowledge, the first empirical demonstration in a decapod crustacean with direct development that, although the percentage of ovigerous females decreases over time, other reproductive variables and juvenile performance do not decline in successive spawnings, at least for the initial six consecutive spawns.

Reproductive development in captive reconditioned female steelhead kelts: evidence for consecutive and skip spawning life histories

Reconditioning of post-spawned anadromous rainbow trout (steelhead kelts, Oncorhynchus mykiss) is being implemented as a recovery tool on the Yakima River in the mid-Columbia River Basin. We assessed reproductive development in female Yakima River kelts by measuring plasma estradiol-17β (E2) and vitellogenin (VG) levels during reconditioning in 2009–2011. Plasma E2 and VG levels showed that fish separated into rematuring (consecutive spawning) and nonrematuring (presumed skip spawning) cohorts by October. Rematuration rates varied from 25% to 65%. Rematuring fish were consistently detected migrating toward spawning areas after release, whereas nonrematuring fish were occasionally detected on spawning migrations the following year. Rematuring fish grew more rapidly than nonrematuring fish over the reconditioning period and had higher muscle lipid levels and condition factor in October. Plasma E2 was elevated in rematuring fish by June–July, whereas plasma VG was elevated by June–August, suggesting that maturation decisions occur early in reconditioning. Rematuring and nonrematuring females could be separated by plasma E2 and VG levels by August–September, enabling separate management of consecutive and presumed skip spawners.

Enhancement of oogenesis/spermatogenesis in meagre Argyrosomus regius using a combination of temperature control and GnRHa treatments

A multiple GnRHa injection method for inducing spawning of high fecundity and quality in meagre was optimized. Specifically, the study (a) examined how long females would continue spawning in response to consecutive, weekly GnRHa injections, if maintained at the natural spawning temperature, and (b) evaluated whether males can produce adequate amounts of good quality sperm for the same period, with the assistance of a GnRHa therapy. Combined with stable temperatures (19–20°C) that are prevalent during the early spawning season (April–May) in the Mediterranean Sea, each weekly GnRHa injection induced ~2 consecutive spawns per week for a period of 17weeks. Fish spawned consistently 2days after treatment and produced high fecundity and egg quality (i.e. fertilization, hatching and early larval development). Maximum mean total fecundity (±S.D.) obtained was 1,415,000±149,000eggskg−1 in 32 spawns, being the highest total season fecundity reported for meagre, and significantly higher than the estimated maximum potential fecundity for the species. At the same time, sperm of consistently high quality (i.e. initial motility, duration of motility and storage survival) was produced in response to treatment with multiple GnRHa implants, though towards the end of the experiment a significant reduction (ANOVA, P≤0.05) in spermatozoa density was observed. This protocol is expected to enhance greatly commercial production of meagre. Statement of relevanceThe present study reports on an optimized protocol for the induction of consistent and repeated spawning in meagre, based on the use of weekly GnRHa injections combined with stable temperatures that are prevalent at the early spawning season in the Mediterranean Sea. This protocol produced eggs of high fecundity and quality (i.e. fertilization, hatching and early larval development) for a period of >4months, and it is expected to enhance greatly commercial production of meagre.

Female Growth and Offspring Quality over Successive Spawnings in a Caridean Shrimp Neocaridina davidi (Decapoda, Atyidae) with Direct Development.

This study analyzed the quality of recently spawned eggs and of juveniles over five and six consecutive spawns, respectively, in a caridean shrimp Neocaridina davidi with direct development. The potential energetic antagonism between reproduction and somatic growth was also evaluated. The number of eggs per spawn per female was highest in the first spawn, while the number of recently hatched juveniles per spawn per female declined in the sixth spawn. Lower lipid concentration and energy content were detected in eggs of the fourth and fifth spawns, which may indicate for the first time a decrease in maternal provisioning as a result of multiple spawning in a decapod with direct development. This result had no effect on the size of eggs or of recently hatched juveniles, nor on the growth performance of juveniles during a 30-day period following hatching. Lipids were the most abundant biochemical component of eggs, followed by proteins and glycogen; the relative proportion of each component was probably related to embryonic development type. Egg volume was unsuitable as an indicator of nutrient content, as no correlation was found between these variables. The physiological costs of reproduction were evident from the lower energy content of females that reproduced versus females that remained virgin. The lower body weight of the reproductive females at the end of the experiment showed that allocation of resources to reproduction occurred at the expense of somatic growth. To our knowledge, this is the first empirical demonstration of a decapod with direct development.

Reproductive biology of the sea anemone shrimp Periclimenesrathbunae (Caridea, Palaemonidae, Pontoniinae), from the Caribbean coast of Costa Rica.

Caridean shrimps are a highly diverse group and many species form symbiotic relationships with different marine invertebrates. Periclimenes rathbunae is a brightly colored shrimp that lives predominantly in association with sea anemones. Information about the reproductive ecology of the species is scarce. Therefore, we collected 70 ovigerous females inhabiting the sun sea anemone Stichodactyla helianthus in coral reefs from the southern Caribbean coast of Costa Rica. Females produced on average 289 ± 120 embryos. The volume of recently-produced embryos was on average 0.038 mm3, and embryo volume increased by 192% during the incubation period. The average embryo mortality during embryogenesis was 24%. The reproductive output was 0.24 ± 0.094, considerably higher than in many other pontoniine shrimps. Females carrying embryos close to hatching showed fully developed ovaries, suggesting consecutive spawning. We assume that the sheltered habitat, living on sea anemones, allows Periclimenes rathbunae to allocate more energy in embryo production than most other free-living caridean shrimps. This is the first record of Periclimenes rathbunae for Costa Rica.

Evolution of egg production and parental contribution in Senegalese sole, Solea senegalensis, during four consecutive spawning seasons

Abstract The purpose of this study was to evaluate the total egg production of three groups of wild Solea senegalensis that were adapted to captivity (B1, B2 and B3) and to evaluate parental contribution through the allocation of larvae hatched over four spawning seasons (2007–2010). Total production, daily relative fecundity, and fertilisation and hatching rates were obtained. In addition, an analysis of egg diameter was performed. The total production resulted in 633 spawns and showed a number of differences in the floating volume rate and the hatching rate between each year. The mean relative fecundity and the fertilisation rate showed interannual stability. Significant differences in production were found between the different breeding tanks. The change in the egg diameter decreased as the breeding season progressed, and the relationship between egg diameter and time, calculated using the spawns of two females, showed a significant correlation (ρ = − 0.426, p = 0.000 and ρ = − 0.362, p = 0.000, respectively) and a significant fit to a cubic regression model (R 2 = 33.6, p = 0.000 and R 2 = 54.3, p = 0.000, respectively). Parentage analysis with four highly polymorphic microsatellites enabled the identification of the parents involved in each spawn, the relationships between males and females over the breeding season and between breeding seasons, and the reproductive rhythms of individual females. The percentage of individuals that participated in the spawns in each tank ranged between 8.7% (B1, 2009) and 51.7% (B3, 2008) annually. Paternity inference of progenies (n = 3630 larvae) showed a high fidelity behaviour in Senegalese sole, with offspring allocated to the same couples throughout the breeding season (87–98%) and even between mating seasons in different years. The period of reproductive activity of the 4 most active females lasted from 96 days (female 37, 2010) to 252 days (female 35, 2009), with intervals between consecutive spawns ranging between 1 and 56 days.

Two-way sex change in the endangered limpet Patella ferruginea (Mollusca, Gastropoda)

Direct observations of sex change were made on the endangered limpet Patella ferruginea in Chafarinas Islands (Alboran Sea) between 2006 and 2011. Individuals of the species were sexed and tagged during spawning season for subsequent monitoring to determine possible sex changes. Mortality was minimized by following a carefully designed sexing protocol. Out of 49 tagged specimens (41–88 mm in size) that could be sexed in successive years (28 males and 21 females), 16 males changed into females between consecutive years (50.0% of males smaller than 70 mm and 100% of males larger than this size), while two females changed sex to males between consecutive spawning seasons (both were smaller than 70 mm). Overall, 36.7% of the limpets monitored changed sex between consecutive years: 57.1% of males became females and 9.5% of females changed to males These observations confirms the occurrence of two-way sex change, or reverse sequential hermaphroditism, in P. ferruginea. Our findings unveil this sexual strategy in this endangered limpet and provide new direction for studies designed to address the mechanisms and factors that determine sex change and its effects on population dynamics.

Reproductive performance in female strains of Nile tilapia, Oreochromis niloticus

The Nile tilapia is among the most cultivated tropical fish in the world, yet little is known about the variations in reproductive characteristics among different strains. There is an interest in evaluating the reproductive performance of females of three tilapia strains. All strains were represented in equal proportion (n = 225), being named as Supreme (SUP), Premium Aquabel (PA), and Chitralada (CHI). These fish were cultivated for 7 weeks in the Aquabel Pisciculture Station (Brazil), from January to March 2011. The PA was the largest strain, with the highest values in all the morphometric parameters we analyzed (weight, total length, standard length and body depth). Among the evaluated reproductive parameters, the PA strain differed significantly from the other two in number and weight of eggs/female, volume of eggs/spawn and number of eggs/kg of fish. The percentage of non-spawning females in the SUP and CHI strains differed significantly from one another, while results for PA showed intermediate values and no significance compared to the other strains (P > 0.05). Among the reproductive parameters analyzed, the percentage of spawned females/week, more than one spawns during 7 weeks, and hatching rate showed no significant differences between strains (P > 0.05). There was a significant correlation (r = 0.69) between water temperature and percentage of spawned females/week. When evaluating the interval between two consecutive spawns, we observed that periods of 21 days were the most frequent in all strains. In conclusion, the strain that showed the best results in all morphometric and in most reproductive parameters we evaluated was the PA.