Spawning In Species Research Articles

Positive selection on ADAM10 builds species recognition in the synchronous spawning coral Acropora.

The reef-building coral Acropora is a broadcast spawning hermaphrodite including more than 110 species in the Indo-Pacific. In addition, many sympatric species show synchronous spawning. The released gametes need to mate with conspecifics in the mixture of the gametes of many species for their species boundaries. However, the mechanism underlying the species recognition of conspecifics at fertilization remains unknown. We hypothesized that rapid molecular evolution (positive selection) in genes encoding gamete-composing proteins generates polymorphic regions that recognize conspecifics in the mixture of gametes from many species. We identified gamete proteins of Acropora digitifera using mass spectrometry and screened the genes that support branch site models that set the "foreground" branches showing strict fertilization specificity. ADAM10, ADAM17, Integrin α9, and Tetraspanin4 supported branch-site model and had positively selected site(s) that produced polymorphic regions. Therefore, we prepared antibodies against the proteins of A. digitifera that contained positively selected site(s) to analyze their functions in fertilization. The ADAM10 antibody reacted only with egg proteins of A. digitifera, and immunohistochemistry showed ADAM10 localized around the egg surface. Moreover, the ADAM10 antibody inhibited only A. digitifera fertilization but not the relative synchronous spawning species A. papillare. This study indicates that ADAM10 has evolved to gain fertilization specificity during speciation and contributes to species boundaries in this multi-species, synchronous-spawning, and species-rich genus.

Institutional amnesia pushes fish spawning aggregations towards extirpation

Abstract How institutions create and manage knowledge has been explored in the context of management and business science. However, little effort has been made to understand how, and why, these institutions forget what works or does not work, and no research in this field has been conducted in conservation or fisheries science. This paper examines the concept of institutional amnesia by focussing a lens on fish spawning aggregations and efforts to monitor and protect them in the Mesoamerican Reef. For over 20 years, underwater visual census survey data has been collected periodically at 36 spawning aggregation sites, and grey literature is available since the 1940's, yet managers and conservation practitioners report that abundance tendencies for 48% of grouper and snapper spawning species across the 36 sites are ‘Unknown’, despite measurable >99% declines in fish abundance in some cases. This text examines the reasons why site managers are uncertain in their reporting. The central argument is that institutional amnesia (resulting from factors such as staff turnover, ineffective institutional learning, poor record keeping and a lack of storytelling) is contributing to suboptimal ecological outcomes for spawning aggregations, which are likely to continue unless measures are taken to ensure the continuity of institutional knowledge. Read the free Plain Language Summary for this article on the Journal blog.

The newly built Ribb Reservoir fisheries, Tana Sub‐basin, Ethiopia: New fishery establishment, diversity, production, challenges and management

AbstractIn the future, agriculture alone may not produce the food needed to feed the increasing world population. Hence, it can be augmented by developing irrigation and water resources, mainly fisheries resources. In Ethiopia, especially in the Tana Sub‐basin, the expanded irrigation practices by building dams and weirs along the tributaries of Lake Tana did not consider fisheries nor the development and management. The aim of this research was, therefore, to promote fisheries and integrate them into the irrigation systems of the Ribb Reservoir in Ethiopia. During the sampling time (from September 2020 to August 2021), primary and secondary data collection and discussions with experts and fishers were conducted. Although the dam prevented the upstream spawning migration of the Labeobarbus species, the reservoir created a new fisheries development. Water quality parameters, such as temperature (23.82 ± 1.38°C), pH (6.36 ± 0.64) and dissolved oxygen (8.84 ± 3.54 mgl‐1), were within the acceptable range for fish. Of the 11 identified fish species, L. nedgia and L. surkis were the most and the least common species, respectively. Riverine and cut spawner species were the sources of the population. However, Oreochromis niloticus (Nile tilapia) was restocked in 2017 to increase the livelihoods of fishers. The Fulton condition factor, K values of L. nedgia (1.63 ± 0.25), L. intermedius (1.70 ± 0.27), C. gariepinus (0.61 ± 0.13) and O. niloticus (1.65 ± 0.29), and their ‘b’ values were <3. The newly established fishery in the reservoir is the source of income for fishers, and its annual production has been shown to increase from 148.5 to 1034.1 tons/year, indicating fish are adapting to the reservoir. However, the fishery has faced many challenges, such as illegal fishing, fisher engagement, and fishing gears. Limiting the number of fishers, restrictions on fishing gears and seasonality of fishing are some of the mitigations.

Towards the Development of Standardized Bioassays for Corals: Acute Toxicity of the UV Filter Benzophenone-3 to Scleractinian Coral Larvae.

Coral reefs have been declining globally at a historically unprecedented rate. Ultraviolet (UV) filters used in sunscreens may contribute to this decline at local scales, which has already led to bans on various organic UV filters in some regions. However, the underlying studies for these bans demonstrated significant flaws in the experimental design due to a lack of validated and standardized testing methods for corals. This study aimed to investigate options for the development of a standard acute toxicity test for the larval stage of scleractinian corals. Planula larvae of two brooding (Leptastrea purpurea and Tubastraea faulkneri) and two spawning (Acropora digitifera and A. millepora) species were exposed to the organic UV filter benzophenone-3 (BP3) for 48 h under static conditions. We observed interspecific variations in toxicity, with A. digitifera being the most sensitive (LC50 = 0.75 µg L−1) and T. faulkneri the least sensitive (LC50 = 2951.24 µg L−1) species. Inhibition of settlement was found to be a useful endpoint leading to an EC50 of 1.84 µg L−1 in L. purpurea larvae. Although the analytical challenges of measuring lipophilic substances in small volume test setups remain, the here applied test design and selected endpoints are suitable for further validation and subsequent standardization.

New Evaluation of Postovulatory Follicle Degeneration at High-Temperature Regimes Refines Criteria for the Identification of Spawning Cohorts in the European Anchovy (Engraulis encrasicolus).

Simple SummaryWide fluctuations in abundance arising from variations in reproductive success are characteristic of many marine fish populations, including several pelagic fish species. The European anchovy is an economically and ecologically important resource, representing one of the most abundant species of the total Mediterranean fishery production. According to recommendations by the European Union, management plans should improve estimates of model parameters or biomass evaluation to provide a sustainable stock exploitation. The proportion of females spawning per day is one of the main parameters, including ichthyoplankton methods, for spawning biomass evaluation and is usually assessed by the postovulatory follicle (POF) method. Because of POF resorption rate is species-specific and influenced by residence temperature, the application of this method needs validation for species and area. This manuscript aimed to evaluate the resorption rate of postovulatory follicles in European anchovy in the central Mediterranean Sea, describing each degeneration stage based upon its histological features and estimating the duration of each POF stage in relation to water temperature experienced by the target species during the spawning peak. The provided results should allow for methodological advances in estimating the spawning biomass and in studying of reproductive output fluctuations, particularly for sustainable exploitation purposes.Accurate stock assessment estimates of fish resources are essential in fishery management. Wide fluctuations in abundance arising from variations in reproductive success are characteristic of many marine fish populations, including multiple spawner species. The proportion of females spawning per day is crucial in the application of egg production methods for spawning biomass evaluation and, usually, is assessed by postovulatory follicle (POF) method. Describing each degeneration stage of POF based upon its histological features allows for obtaining an aging key for postovulatory follicles. The commercially valuable European anchovy (Engraulis encrasicolus) was selected as a case study, which breeds during the summer in temperate waters (24 °C–25 °C). A collection of ovary slides, sampled in the central Mediterranean Sea during the spawning peak, provided a 24 h cycle coverage. These observations allowed us to evaluate the duration of each POF stage at water temperature experienced by anchovy in the study area. Present results demonstrated the POF degeneration progress at a faster rate than reported by previous investigations, carried out in cooler oceanic waters. Furthermore, the present study displayed the presence of two anchovy spawning cohorts sampled along a 24-h cycle. Therefore, this study not only provides useful insight for more accurate POF degeneration evaluation in temperate waters, but also suggests that current estimates should be complemented with validation studies according to different temperature regimes.

Reproductive biology of Caspian goby, Neogobius caspius (Eichwald, 1831) in the southern Caspian Sea (Noor beach)

This study provides fundamental information on some key aspects of the reproductive biology of Neogobius caspius, a Caspian Sea endemic, poorly studied Gobiidae fish species. In total, 222 specimens were captured monthly from Noor coastal waters in southern part of the Caspian Sea from April to October 2016, while water parameters (temperature, salinity and pH) were monitored weekly. Gonadosomatic and hepatosomatic indices suggested that the reproductive period of this species was in April to May. Peak of Fulton and Clark’s condition factors appeared in April and May for female and male specimens, respectively, then a declining trend appeared until June that remained constant until the end of October. Absolute fecundity ranged from 418 to 1798 oocytes per individual (mean: 1013±357 (SD) oocytes, n=41), which was highly related to the length and weight of fish and weight of gonads. Oocyte mean diameter ranged 35.85±11.80 µm in immature stage to 1103.86±172.01 µm in mature stage. Five stages of maturity for female and four stages for male specimens were described based on macroscopic features and histological description. N. caspius appeared as an iteroparous and a batch spawner species, producing more than one oocyte clutch in a single reproductive season.

Species Composition and Hybridization among Native and Nonnative Catostomid Fishes in Two Streams of the Gunnison River Basin, Colorado

We report results from a 3-year field investigation to limit hybridization between native and nonnative suckers in 2 small tributaries of the Gunnison River basin, Delta County, Colorado. Upstream movement to spawning habitat was selectively impeded by picket weir in intermittent Cottonwood Creek. There, native suckers were identified based on morphological characters in the field and were transferred upstream of the weir, whereas nonnative fishes were excluded from upstream movement. Another stream, Potter Creek, was not impeded by weir. Genetic identification of adult fishes in both streams was consistent with morphological identification in the field. Larval genetic identification was consistent with probable spawning species in Potter Creek. However, in Cottonwood Creek, larval fish proportions differed significantly from likely spawners. Proportions of nonnative suckers were high in Cottonwood Creek because exclusion structures were compromised by flooding during the spawning season. Yet, instream control of spawning by nonnative fishes has potential for reducing the incidence of hybridization, but practical challenges remain for implementation in the field.

Embryological development of the high-altitude killifish Orestias ascotanensis Parenti 1984 (Teleostei: Cyprinodontidae)

Orestias ascotanensis Parenti is a critically-endangered fish species endemic to the Ascotan salt pan springs. Given the importance of reproduction and early development in effective conservation of fish populations, this study describes the embryonic development of O. ascotanensis under laboratory conditions. Between 2014 and 2015, 50 individuals were captured and maintained under controlled conditions, including temperature, photoperiod and feeding regimen, to induce spawning for artificial fertilization. Females were subjected to hormone therapy with Ovaprim®. Water temperature was maintained at 20 °C (± 1 °C), conductivity at 2800–3600 μS·cm−1 and photoperiod at 16:8 (light hours: dark hours). Males showed changes in color and courtship behavior, and females developed a slightly bulging belly. Eggs were 1.55–2.5 mm in diameter, with abundant yolk and dozens of adhesion filaments. Embryonic development lasted 14–18 days; it was divided into five periods, which can be sub-divided into 21 stages, from fertilization to hatching. O. ascotanensis showed indications of partial spawning species, including oocytes at different stages of development, relatively large eggs as compared to adult fish length and low batch spawning. Characteristics such as partial spawning, highly-pigmented eggs and larvae and advanced larval development at hatching could be adaptations to the extreme conditions of the salt pan springs, including high levels of ultraviolet radiation and salinity as well as significant daily temperature changes.

СОСТОЯНИЕ ПОПУЛЯЦИИ СУДАКА НИЖНЕГО ТЕЧЕНИЯ РЕКИ УРАЛ

In domestic and foreign markets a great demand for pike perch is caused by the fact that its meat is a digestible and dietetic product. Due to growing scales of exploration and production of oil, as well as of poaching in the last years pikeperch and other species suffer from anthropogenic load. In 1990 spike perch catches reached 4.49.000 tons and made 1/3 of total catch of semi anadromous and river fish. During the last decade pike perch catches have decreased in the Ural-Caspian region up to 380 t, according to data of 2016. The study of pike perch populations on fishing zones of the Ural (delta, Malaya Dambinskaya fishing ground) covered the data obtained in 2010-2016. There have been studied migrating periods of pike perch to the spawning grounds. Since 2011 there has been stated a drastic decrease of sire number and a much less catch of pike perch per one casting in autumn, which was caused by the permission for fishing in the coastal part of the Caspian Sea. According to the research data, there have been given size-weight parameters of pike-perch producers in the Ural river during 10 years (2006-2016). The tendency to juvenation of spawning pike perch species is stated due to increasing share of the first spawning species, as well as due to decreasing number of male species in the catches as their age increased. Fultin and Clark’s condition coefficients are shown. Importance of pike perch as a commercial species in the ecosystem of the Ural-Caspian fishery zone contributes to define the following recommendations on saving and restoring pike perch population: to reduce commercial catches in the estuarine area of the Ural; to forbid commercial fishing in the coastal area of the north-east part of the Caspian Sea; to intensify fishery inspection in the Urals.

Broadcast Spawning Coral Mussismilia hispida Can Vertically Transfer its Associated Bacterial Core

The hologenome theory of evolution (HTE), which is under fierce debate, presupposes that parts of the microbiome are transmitted from one generation to the next [vertical transmission (VT)], which may also influence the evolution of the holobiont. Even though bacteria have previously been described in early life stages of corals, these early life stages (larvae) could have been inoculated in the water and not inside the parental colony (through gametes) carrying the parental microbiome. How Symbiodinium is transmitted to offspring is also not clear, as only one study has described this mechanism in spawners. All other studies refer to incubators. To explore the VT hypothesis and the key components being transferred, colonies of the broadcast spawner species Mussismilia hispida were kept in nurseries until spawning. Gamete bundles, larvae and adult corals were analyzed to identify their associated microbiota with respect to composition and location. Symbiodinium and bacteria were detected by sequencing in gametes and coral planula larvae. However, no cells were detected using microscopy at the gamete stage, which could be related to the absence of those cells inside the oocytes/dispersed in the mucus or to a low resolution of our approach. A preliminary survey of Symbiodinium diversity indicated that parental colonies harbored Symbiodinium clades B, C and G, whereas only clade B was found in oocytes and planula larvae [5 days after fertilization (a.f.)]. The core bacterial populations found in the bundles, planula larvae and parental colonies were identified as members of the genera Burkholderia, Pseudomonas, Acinetobacter, Ralstonia, Inquilinus and Bacillus, suggesting that these populations could be vertically transferred through the mucus. The collective data suggest that spawner corals, such as M. hispida, can transmit Symbiodinium cells and the bacterial core to their offspring by a coral gamete (and that this gamete, with its bacterial load, is released into the water), supporting the HTE. However, more data are required to indicate the stability of the transmitted populations to indicate whether the holobiont can be considered a unit of natural selection or a symbiotic assemblage of independently evolving organisms.

Production of Nonadhesive Eggs by Flathead Chub and Implications for Downstream Transport and Conservation

AbstractPlains stream fishes in North America, including flathead chub Platygobio gracilis, are negatively affected by stream-flow alterations and fragmentation, and limited information on egg type and reproductive strategy hinders their conservation. On the basis of several lines of evidence, including laboratory culture, observations of reproduction in captivity, and capture and rearing of eggs from Fountain Creek, Colorado, we report that flathead chub produce nonadhesive eggs. Flathead chub eggs are relatively small at 2.3 mm mean diameter, have a greater yolk-to-egg volume ratio and thus sink faster, and take longer to hatch, compared with nonadhesive eggs from pelagic spawning species. Flathead chub are also longer lived compared with pelagic spawning species and the wider variety of habitat types they occupy may influence upstream egg retention. Although spawning mode (e.g., pelagic, lithopelagic, other) is incompletely known for flathead chub, habitat needs in terms of flows and reach lengths suitable for reproduction and recruitment may vary with habitat type but may be similar to that for other pelagic spawning species. Accommodating specialized reproductive life histories of fishes, including egg type and transport characteristics, in stream conservation planning may assist with maintaining or enhancing populations of all Great Plains cyprinids, including increasingly rare flathead chub.

Reproductive strategy of forkbeard, Phycis phycis, from the Portuguese coast

Knowing fish reproductive strategy is essential for understanding population dynamics. This study intends to define the spawning season, length at first maturity, fecundity type, and estimate fecundity of forkbeard, Phycis phycis, from the Portuguese coast. Monthly samples collected from commercial landings between May 2011 and December 2012 were used. Results show that forkbeard is a group-synchronous and batch spawner species. Mature females were found between September and January, mature males were found between August and January, and a significant concomitant increase in gonadosomatic index suggests a spawning season from September to January. Length at first maturity was estimated as 35.9 and 28.5 cm TL for females and males, respectively. Reproductive abnormalities—mosaic intersex, follicular cysts in ovaries, and early mature males—were detected. For fecundity-type definition, a hiatus between primary and secondary growth oocytes was detected. A significant increase in the mean diameter of secondary growth oocytes and a decreasing trend in their number during the spawning season were observed. The intensity of α-atresia was low throughout the spawning season. These four criteria suggest that forkbeard has determinate fecundity. Mean relative annual fecundity estimated was 1833 ± 857 oocytes g−1 gutted weight. Non-reproductive females that skipped a spawning season attained 36.1 %.

Vertical distribution and migration of fish larvae in the NW Iberian upwelling system during the winter mixing period: implications for cross‐shelf distribution

AbstractThe vertical distribution and vertical migrations of fish larvae and implications for their cross‐shelf distribution were investigated in the northern limit of the NE Atlantic upwelling region during the late winter mixing period of 2012. The average positive values of the upwelling index for February and March of this year were far from normal, although the average hydrographic conditions during the period of study were of downwelling and the water column was completely mixed. Fish larvae, most in the preflexion stage, were concentrated in the upper layers of the water column and their distribution was depth stratified, both day and night. However, the larval fish community was not structured in the vertical plane and fish larvae did not show significant diel vertical migration (DVM), although five species showed ontogenetic vertical migration. In regions of coastal upwelling and in the absence of DVM, the location of fish larvae in the water column is crucial for their cross‐shelf distribution. Thus, the cross‐shelf distribution of the six most abundant species collected in this study can be explained by the surface onshore flow associated with coastal downwelling, retaining larvae of the coastal spawning species with a relatively shallow distribution in the shelf region and transporting larvae of slope spawning species onto the shelf. The wide vertical distribution shown by larvae of the offshore spawning species could be an adaptation of these species to ensure that some larvae reach the inshore nursery areas.

Life-history strategies associated to reproduction of three Hyphessobrycon species (Characidae) in lentic environments of upper Paraná River basin

AIM: Life-history strategies in fish include essential parameters related to offspring survivorship, fecundity and time of reproduction, which represent adaptive traits that enable a species to deal with spatial and temporal variability of abiotic conditions. This study aimed to compare reproductive traits associated to life-history theory for three Hyphessobrycon species from two lentic environments (four natural oxbow lakes and a man-made reservoir) of Mogi Guaçu River, upper Paraná River basin. METHODS: Specimens were collected with four minnow traps between August 2005 and July 2006 to cover dry and wet seasons (three samples in each season, and three samples in each environment). RESULTS: Reproductive strategy of H. bifasciatus and H. eques, which predominated in the oxbow lakes, differed from H. anisitsi in the reservoir. Hyphessobrycon bifasciatus and H. eques were single spawners with lower fecundity and size at sexual maturity, but invested more in number of eggs per body gram, while H. anisitsi was a multiple spawner species with higher fecundity, larger size at sexual maturity and body size. CONCLUSIONS: In seasonal environments, single spawners are synchronized with the floods to maximize juvenile survivorship, while reservoirs harbors multiple spawners’ fish due to the reduced fluctuation between high and low floods resulting from dam operation. Therefore, the seasonal condition in the oxbow lakes due to the flood pulse favored single spawners’ tactic, as showed by H. bifasciatus and H. eques. In contrast, the multiple spawning of H. anisitsi seems to be related to the more stable environmental condition throughout the year provided by the dam. Life-histories reported herein to Hyphessobrycon species must be common to other characid fishes inhabiting similar environments.

Longevity in maternal transmission of isotopic marks in a tropical freshwater rainbowfish and the implications for offspring morphology

Transgenerational marking is increasingly being used to study the early life history, biology and ecology of fishes. However, the timeframe over which the injected enriched stable isotopes remain in the mother and are passed onto her offspring is largely unknown. Similarly, we have relatively little knowledge of the effects of isotope labelling on the morphology of offspring. In this study, we injected adult female eastern rainbowfish (Melanotaenia splendida) with two doses (20 µg g–1 and 40 µg g–1) of enriched 137Ba or 87Sr stable isotopes to mark the otoliths of their larvae and examine the effects of isotope labelling on larvae morphology. Isotope ratios in larval otoliths were significantly different from controls in larvae hatched up to 174 days post-injection, indicating that enriched isotopes can mark the larvae of this daily spawning species up to 6 months after a single injection. Isotope-marked larvae displayed variable, but generally increased physical size, indicating that enriched stable isotope labelling may have some unintended effects on larvae morphology. Consequently, transgenerational marking provides a long-term tool for marking the offspring of M. splendida to disentangle their patterns of survivorship and dispersal, with the caveat that such studies should be interpreted in light of potential isotope-related changes in offspring morphology.

Survival of Drowning Sperm: Do Spermatozoa from External Fertilizers Adapt to Differing Osmotic Environments Through the Use of Aquaporins?

In spawning animals, external fertilization usually requires spermatozoa to become activated (motile) in the environmental medium and then quickly locate and contact the egg. In most teleost fish, sperm are usually quiescent within the testes and seminal fluid but then initiate vigorous motility upon dilution into the external medium in which spawning occurs [1]. In teleost fish sperm, an increase in intracellular calcium occurs upon motility initiation by way of different signaling mechanisms (reviewed by [2]) [3–5]. Following dilution into medium, four different triggers of sperm motility in teleosts have been identified: 1) a reduction in external K þ upon dilution of semen initiates motility in salmonids [6, 7], 2) hypotonic exposure after dilution into freshwater is the trigger in nonsalmonid freshwater fishes [8–11], 3) hypertonic exposure initiates sperm motility in marine teleosts [12, 13], and 4) egg-associated molecules activate sperm motility [14– 17]. While there are many examples in the literature of specific ions and ion channels playing roles in sperm motility initiation and maintenance, it is known that the osmotic pressure of the medium alone can affect both motility initiation (reviewed by [5]) [18] and survival of sperm following dilution. In some of these studies, osmotic changes may stimulate stretch-activated channels that trigger motility initiation [19]. Sperm volume changes are known to occur and are associated with the osmotic change upon dilution in hypotonic medium [20]. These volume changes may, by themselves, activate stretchactivated channels and/or water channel proteins, termed aquaporins, which play a role in the activation of sperm motility in seabream spermatozoa [21]. In this case, the dilution of seabream spermatozoa into seawater results in a hyperosmotic change, and the water efflux through aquaporins that results creates an increase in intracellular ions; this is believed to be responsible for activation of adenylyl cyclase and the cAMP-signaling pathway causing phosphorylation of flagellar proteins [22]. The proposed model for aquaporin-mediated motility initiation is shown in Figure 1 [21]. A new study in this issue of Biology of Reproduction by Chauvigne et al. [23] has now shown that multiple aquaporins are associated with water and fluid homeostasis during spermatogenesis and in the male reproductive tract, as well as in mature motile spermatozoa. This study demonstrates that the water-specific aquaporin Aqp1aa and the glycerol/urea/ water-transporting channel Aqp10b are both present (with others) in the plasma membrane of both the head and flagellum of ejaculated sperm. Inhibitors of aquaporin channels are shown to inhibit motility, indicating a direct role for aquaporins in sperm motility initiation in this marine teleost. The Chauvigne et al. study [23] isolated and functionally characterized five additional members of the aquaporin superfamily using a comprehensive approach of immunolocalization and biochemical fractionation of sperm. They have shown, for the first time, that a nonmammalian vertebrate possesses up to seven classes of aquaporins that are differentially expressed during spermatogenesis and spermiogenesis, with several of these being redistributed in the plasma membrane upon motility initiation. During hyperosmotic shock upon dilution in seawater, Aqp1aa may mediate water efflux, whereas Aqp10b might play a role in maintenance of motility [21, 23]. The data in this new study clearly show the conservation of aquaporin paralogs in the male reproductive tract of a nonmammalian vertebrate and highlight the similarities in the pattern and localization of aquaporins both in the testes and in mature sperm, as has been described in mammals [24, 25, 26]. One of the most intriguing findings of the current Chauvigne et al. study [23] is the change in intensity of immunolabeling of Aqp1ab as motility is initiated, with the head becoming more intense and the midpiece becoming strongly labeled. Aqp8b did not change intensity or labeling pattern in the head after activation, but did relocate to the midpiece. Aqp10b also showed a strong increase in intensity in the head upon motility activation. These changes in intensity and spatial patterns of sperm plasma membrane aquaporins during motility initiation in a hypertonic medium strongly suggest that they are regulating water/fluid efflux and have a direct role in motility initiation and maintenance. Such a direct role for aquaporins in motility regulation in external spawning species needs serious consideration in other species and across phyla. Species that reproduce in environments of varying salinities [3, 27] would be of particular interest to study, as one might hypothesize that at higher salinities aquaporins may play a direct role in motility initiation; however, at lower salinities (iososmotic or hypoosmotic), other mechanisms may be responsible. Now that we know the potential importance of aquaporins in sperm motility initiation in a marine teleost from this study, the functionality and redistribution of these waterregulating permeability membrane proteins would be of great Correspondence: Gary N. Cherr, University of California Davis Bodega Marine Laboratory, P.O. Box 247, Bodega Bay, CA 94923. E-mail: gncherr@ucdavis.edu

Evaluation of the current state of small pelagic fisheries in the Colombian Pacific: ensuring the sustainability of the resource and evaluating its response to climatic events

Abstract. Commercial fishing of small pelagic species in Colombia, mainly "carduma" (Cetengraulis mysticetus) and "plumuda" (Opisthonema spp.), has been recorded since 1970. Both are used to produce fish meal for aquaculture and poultry and for canned foods. These two species are filter feeders, and therefore support higher levels of the food chain (other fish, birds and marine mammals), and artisanal fishermen use them as bait. Between 2005 and 2010, 86.131 t have been captured (X = 14.355 t yr−1), and a strong reduction was noticed in 2009 (6.969 t). Carduma is considered a total spawning species. However, from 1997 to 2000 and from 2008 to date, atypical reproductive behavior of the species has been observed, including partition of the spawning period and the reduction of the volume of eggs and larvae released to the environment. Both situations are linked to thermal anomalies such as El Niño and La Niña events. Therefore, the process of assigning the global quota of extraction has been revised to take into account the reduction of total capture during the last years and the inconsistencies of the reproductive processes. The Ministry of Agriculture reduced the quota by 10%, leaving available a total of 27 000 t for 2010 and reduced it again to 25 000 t for 2011. It is important to maintain the management measures that are already implemented on this resource (bans during reproduction seasons, catch quotas, regulation of mesh sizes for the fishing nets, and limiting the number of new vessels) and considering other measures such as season closure for recruitment and establishment of marine protected areas to further contribute to the sustainability of these fisheries.

Synthesizing larval competence dynamics and reef‐scale retention reveals a high potential for self‐recruitment in corals

Many organisms have a complex life-cycle in which dispersal occurs at the propagule stage. For marine environments, there is growing evidence that high levels of recruitment back to the natal population (self-recruitment) are common in many marine organisms. For fish, swimming behavior is frequently invoked as a key mechanism allowing high self-recruitment. For organisms with weak-swimming larvae, such as many marine invertebrates, the mechanisms behind self-recruitment are less clear. Here, we assessed whether the combination of passive retention of larvae due to re-circulation processes near reefs, and the dynamics of settlement competence, can produce the high levels of self-recruitment previously estimated by population genetic studies for reef-building corals. Additionally, we investigated whether time to motility, which is more readily measurable than competence parameters, can explain the between-species variation in self-recruitment. We measured the larval competence dynamics of broadcast-spawning and brooding corals and incorporated these in a model of larval retention around reefs to estimate the potential for self-recruitment and assess its variation among species and reefs. Our results suggest that the larvae of many corals, even those with an obligate planktonic phase, develop with sufficient rapidity to allow high levels of self-recruitment, particularly for reefs with long water retention times. Time to motility explained 77-86% of the between-species variation in potential self-recruitment in scenarios with a realistic range of retention times. Among broadcast spawners, time to motility was strongly and positively correlated with egg size, i.e., broadcast spawner species with small eggs developed more rapidly and exhibited greater potential for self-recruitment. These findings suggest that, along with water retention estimates, easy-to-measure species traits, such as egg size and time to motility, may be good predictors of potential self-recruitment, and therefore may be used to characterize the spectrum of self-recruitment in corals.

Intraspecific variation in reproductive potential with maternal body size in Gulf killifish Fundulus grandis

Gulf killifish Fundulus grandis show promise for commercial development as a baitfish species marketed to anglers on the U.S. Gulf Coast. Additionally, fishes in the genus Fundulus are increasingly cultured as model organisms for various fields of scientific inquiry. Research examining effects of maternal body size on reproduction in this genus and more generally in fractional spawning species with eggs capable of terrestrial development is lacking. The present study assessed the effects of female body size on reproductive investment in laboratory held Gulf killifish as well as subsequent implications for larvae. Larger females had significantly higher fecundity and produced individual eggs of greater volume. Gonadosomatic index more than doubled as female body mass increased from 6.9 to 12.9g, but did not increase significantly in females of body mass>12.9g. Larger eggs required significantly longer incubation periods, and newly hatched larvae from larger eggs had more endogenous nutritional resources but shorter body length. Experimental results describe maternal effects in a fractional spawning species producing eggs with the ability to incubate terrestrially. Results also provide practically useful information for aquaculturists as F. grandis are increasingly cultured commercially and in laboratory settings.

Recruitment Patterns and Habitat Use of Young-of-the-Year Bluefish along the United States East Coast: Insights from Coordinated Coastwide Sampling

Protracted spawning and pulsed juvenile production are common in coastal spawning fishes, the phenology of which determines potential environmental effects on recruitment. This article examines bluefish (Pomatomus saltatrix), a cosmopolitan coastal spawning species that produces multiple cohorts of juveniles utilizing both estuarine and coastal habitats as nurseries along the U.S. east coast. To determine recruitment on a coastwide basis, ocean (bottom, neuston, and surfzone) and estuarine habitats were sampled in Florida and North Carolina south of Cape Hatteras in the South Atlantic Bight, and Maryland, New Jersey, and New York in the Middle Atlantic Bight. This coordinated sampling effort across multiple habitats with multiple gears on a coastwide basis allowed the resolution of the occurrence, growth, and movement of cohorts along the coast. Production of the spring-spawned cohort occurred in both South Atlantic Bight and Middle Atlantic Bight habitats, while summer-spawned cohort production was limited to the Middle Atlantic Bight. Information from the present study is synthesized with prior research to develop a conceptual model of the seasonal patterns of YOY bluefish habitat use and to emphasize the value of coordinated sampling at a large spatial scale in understanding recruitment processes in this and potentially other important marine species.