In 1988 laboratory presentations, bay anchovy, and Atlantic menhaden tested positive as potential predators. Consumption of striped bass larvae by bay anchovy increased at higher prey densities to a maximum of 42 larvae/h at prey densities of 1,650/m&\sp3&. Examination of 229 stomachs of bay anchovy collected during peak spawning in 1988 and 1989 provided direct evidence of predation on striped bass eggs and larvae. The relationship between patterns of survival inferred from the back-calculation of juvenile hatchdates were compared with data sets describing predator and prey fields, egg production, food abundance, and changing environmental conditions during the 1988 and 1989 spawning seasons. The physical factors pH, rainfall, dissolved oxygen, and water temperature were measured at 30-minute intervals and observations of predator, prey, egg and larval densities were recorded weekly or semi-weekly. In 1988, a year of average recruitment, only 11% of the juveniles aged (n = 78) were born during the week of peak spawning when over 48% of the eggs were produced. In 1989, a year of high recruitment, the temporal distribution of juvenile hatchdates more closely followed the distribution of eggs with 30% of the juveniles (n = 96) born during the week of peak spawning when 40% of the eggs were spawned. Potential fish predators were collected in greater numbers during peak spawning in 1988 (61/100m&\sp3&) than during the same period of time of 1989 (12/100m&\sp3&). Water temperatures were lower during peak spawning in 1988 (16&\sp\circ&C) than during 1989 (19&\sp\circ&C). Also, prey items for first-feeding larvae decreased the week following peak spawning in 1988 from an average number of 194 to 74 individuals/l. Lower water temperatures and reduced food densities in 1988 may have produced a combined effect of prolonging developmental stages of striped bass eggs and larvae, thereby making them more susceptible to elevated predator densities. Dissolved oxygen values were inversely related to water temperature, reaching low values of about 6 mg/l after water temperature reached about 25&\sp\circ&C and spawning had ceased. Although pH values were usually around 7.0 throughout the 1988 and 1989 spawning seasons, pH depressions associated with rainfall were noted during both years.

The effects of tributyltin (TBT) on phorbol myristate acetate (PMA)- and calcium ionophore (A23187)-stimulated peritoneal macrophages from oyster toadfish (Opsanus tau) were evaluated in a luminol-dependent chemiluminescence (CL) assay. PMA-stimulated CL responses were increased by in vitro exposure to 50 ug/L TBT, but depressed to baseline values by 500 ug/L TBT. A23187-stimulated CL increased with 5 ug/L and 50 ug/L TBT, and depressed by 500 ug/L TBT. Responses stimulated by synergistic doses of PMA and A23187 were increased by 50 ug/L TBT and depressed by 500 ug/L TBT. Enhanced PMA- and A23187-stimulated CL following TBT exposure returned to baseline values after extracellular calcium was removed. In the absence of PMA or A23187, 50 ug/L TBT stimulated a significant CL response that was inhibited by chelation of extracellular calcium. Uptake of calcium-45 was greatly increased with 50 ug/L TBT but depressed by 500 ug/L TBT. Results suggest that low TBT concentrations stimulate calcium influx and enhancement of reactive oxygen intermediate formation, while high TBT concentrations cause membrane dysfunctions which inhibit calcium flux and depress activation sequences. The physiological basis of TBT-stimulated macrophage activation was investigated in vitro. Inhibition of TBT-stimulated CL by sodium benzoate (.OH scavenger) and superoxide dismutase (.O&\sb2& scavenger) was most similar to PMA-stimulated CL, indicating a role of NADPH oxidase activity in TBT-stimulated CL. Inhibition by nordihydroquaiaretic acid (lipoxygenase antagonist) was similar to PMA-, PMA + A23187-, and A23187-stimulated CL, indicating a common role of leukotrienes in activation responses. Inhibition by indomethacin (cyclooxygenase antagonist) was most similar to PMA + A23187-, and A23187-stimulated CL, indicating a common role of prostaglandins in activation responses. Inhibition by isobutylmethylxanthine (phosphodiesterase antagonist) was most similar to PMA- and A23187-stimulated CL, indicating a role of cyclic neucleotides in activation regulation. Inhibition of TBT-stimulated CL by verapamil (calcium channel antagonist) and trifluoperazine (calmodulin antagonist) were most similar to PMA + A23187- and A23187-stimulated CL, indicating the role of calcium in TBT-stimulated macrophage activation. Therefore, TBT-stimulated macrophage activation is initiated by an increased plasma-membrane calcium flux. The influence of in vivo TBT exposure was compared with the effects of in vitro exposure. Fish were treated (i.p. injections) weekly for six weeks with either sham, vehicle, 0.250, 0.750, or 2.5 mg/kg TBT. Macrophages were isolated and PMA + A23187- and TBT (50 ug/L)-stimulated CL was compared between treatment groups. Chemiluminescence was reduced in a dose-dependent manner in response to both PMA + A23187 and TBT (50 ug/L). It is concluded that TBT supresses macrophage function following both in vivo and in vitro exposure. The mode of action appears to be an interference with plasma membrane calcium transport, therefore inhibiting both intracellular and intercellular signal transduction.

Many production activities typically produce undesirable outputs, e.g., the production of the pollutant sulfur dioxide in the generation of electricity. Traditional economic metrics may overstate the efficiency and productivity of these production activities by failing to account for the undesirable outputs. These omissions can lead to conclusions that are biased against resource conservation and protection. Many fisheries capture their target species concomitantly with undesirable outputs such as bycatch of juvenile fish, marine mammals, sea birds, and sea turtles. One such fishery is the California-Oregon (CA/OR) drift gillnet fishery (DGNF), which incidentally takes protected species, such as sea turtles and marine mammals while harvesting swordfish and thresher shark. Beginning in August of 2001, regulatory measures to reduce the take of endangered species (e.g., leatherback sea turtles) have required the annual closure of an area located between Point Conception and 45?? N. latitude, for the time period August 15 to November 15. This regulatory closure acts as a natural experiment for assessing the impact of the time-area closure on the productivity of the CA/OR DGNF. The three primary purposes of this research were to measure the impact of the 2001 time-area closure on the productivity of the CA/OR DGNF, and to estimate the opportunity cost or shadow price of undesirable outputs. These shadow prices provide lower bound estimates of the social costs of conservation regulations intended to protect endangered leatherback sea turtles and other bycatch species. An alternative method which models the joint production of both desirable and undesirable outputs, the directional output distance function approach, was used to estimate the efficiency and productivity of drift gillnet fishing trips, thus crediting trips with reductions in undesirable harvest and increases in desirable outputs for the time period 1996-2008. By incorporating undesirable harvest into the production process, a more appropriate measure of total factor productivity was calculated than what is provided by traditional productivity measures. The new productivity measure can be used to develop more effective policies designed to maintain or improve a fishery's economic performance. The results indicate that efficiency and productivity measures which ignore undesirable outputs substantially misinterpret the economic performance of economic trips. The model that incorporates undesirable outputs indicates that productivity per trip has been growing by 788 pounds of swordfish over the research period relative to the base year. This is considerably lower than the average growth of 964 pounds when undesirable outputs are ignored and 878 pounds when undesirable outputs are allowed to expand. However, post-closure averages suggest that conventional estimates understate the economic performance of the observed trips. Post-closure productivity growth resulted in an increase of 334 pounds of swordfish harvest when adjusted for undesirable outputs. Average trip shadow prices (per animal captured) revealed a conservation opportunity cost for the reduction of undesirable outputs of &2,500 for marketable discards, &6,600 for unmarketable discards, &28,800 for sea turtles, and &9,800 for marine mammals in forgone composite swordfish and thresher shark revenue.

A unifying theory of community regulation in soft-bottom systems remains elusive, despite extensive field studies on factors controlling community structure. Here, I have (1) reviewed models of community regulation, (2) examined the role of predation in controlling benthic diversity along a salinity gradient, (3) examined effects of predation upon an abundant bivalve, Macoma balthica, and (4) revised a model of community regulation in an estuarine soft-bottom system. The Menge and Sutherland (MS) "consumer stress model" posits that consumers feed ineffectively in harsh environments, and the importance of physical disturbance, competition and predation varies with recruitment, environmental conditions, and trophic position. In this model, competition for resources depends directly upon the level of recruitment. I have revised the model to fit soft-bottom systems by changing the recruitment axis to a "recruitment: resource ratio." Hence, the impact of a given level of recruitment depends upon resource availability. According to the MS model, predation is most important in determining community structure when environmental conditions are not severe. I investigated the applicability of the MS model in a soft-bottom estuarine community. I quantified predator abundance, prey abundance and diversity, and the differential effect of predation on species diversity and survival of an abundant prey species, Macoma balthica, along an estuarine gradient in two tributaries of Chesapeake Bay. Benthic diversity was lower in upriver high-stress habitats than downriver low-stress habitats, in agreement with predictions of the MS model. However, the following findings are inconsistent with model predictions: (1) predator abundance was greater upriver, (2) predation intensity and its impact on benthic diversity were greater upriver, and (3) predation-induced mortality of transplanted Macoma balthica clams, and natural mortality of clams were higher upriver. An alternative community regulation model applies to this system because higher predator abundance and predation intensity in higher environmental stress is contrary to the MS model predictions. Predators aggregated upriver where carbon production was increased, and prey were abundant. Hence, a more suitable model for this soft-bottom system is one that incorporates the effects of production and predation along with recruitment, competition and environmental stress.

The reproductive and feeding biology of five syngnathid species of the western Atlantic were studied: the pipefishes Syngnathus fuscus, S. floridae, the lined seahorse Hippocampus erectus of Chesapeake Bay; and the pipefishes S. folletti and Oostethus lineatus, from southern and southeast Brazil, respectively. Male syngnathids incubate eggs received from females in a ventral brood pouch, females do not play any additional role in parental care after mating. This natural sex role reversal is a unique characteristic that all male syngnathids have. In other fishes, parental care is usually a female prerogative. Most pipefishes are polygamous, while seahorses are monogamous. Syngnathus fuscus, S. floridae, and H. erectus have a protracted mating period from May through September in Chesapeake Bay, which varies with environmental conditions and eelgrass biomass. Female S. fuscus are dimorphic, gravid individuals undergo morphological and morphometric adaptations for mating. Female S. floridae and H. erectus are monomorphic. In both, S. fuscus and S. floridae, total sex ratio was skewed toward females, but the operational sex ratio was skewed toward males. Total and operational sex ratio in H. erectus were skewed toward females. In female S. fuscus (123 to 255 mm TL), fecundity was from 101 to 1,643 oocytes, whereas in males (83 to 189 mm TL) fertility was from 22 to 870 eggs/embryos. In female S. floridae (116 to 189 mm TL), fecundity was from 38 to 818 oocytes, whereas in males (91 to 176 mm TL) fertility was from 15 to 820 eggs/embryos. In female H. erectus (60 to 123 mm TL), fecundity varied from 90 to 1,313 oocytes, and in males (80 to 126 mm TL) fertility varied from 97 to 1,552 eggs/embryos. Mating period was not defined for S. folletti. Total sex ratio in this pipefish was skewed toward females, but the operational sex ratio was skewed toward males. Fecundity in females varied from 30 to 219 oocytes, and fertility measured for male brood pouches was from 26 to 181 eggs/embryos. Mating period was not defined for the estuarine and freshwater populations of the opossum pipefish, O. lineatus. Male opossum pipefish develop different coloration in the snout. In both populations, total sex ratio and operational sex ratio were not significantly different from the expected 1:1 ratio. In the estuarine population, fertility varied from 49 to 508 eggs/embryos (males from 101 to 165 mm TL), and in the freshwater population fertility varied from 280 to 897 eggs/embryos (males from 119 to 508 mm TL). Excepting O. lineatus, females in other pipefish species appear to limit males reproductive success. In the seahorse H. erectus, most females do not have the chance to find a mate inside Chesapeake Bay. In all syngnathids, snout size and width limit predation to small size prey. Syngnathus fuscus and H. erectus fed mainly on amphipods (Gammarus mucronatus, Ampithoe longimana, and Caprella penantis). Syngnathus floridae fed mainly on grass shrimps (Palaemonetes pugio and P. vulnaris). Southern pipefish fed predominantly on copepods. The estuarine population of O. lineatus fed more on stoneflies, whereas the freshwater population fed more on mayflies.&\sp*& ftn&\sp*&Originally published in DAI vol. 56. no. 3. Reprinted here with corrected text.

Assessing genetic variation within and among native populations and hatchery stocks of Crassostrea ariakensis using microsatellite markers In response to the dramatic decline of eastern oyster (Crassostrea virginica) populations in the Chesapeake Bay, introduction of the non-native Asian oyster Crassostrea ariakensis has been proposed. Currently several hatchery stocks of C. ariakensis, derived from a few wild populations along the coast of Japan and China, are being maintained in U.S. hatcheries in the Pacific northwest and on the east coast. In recent years, as the risks of the proposed introduction are being assessed, these hatchery animals have been widely used for various research or comparative studies on this species' ecology, biology and disease tolerance, although to date only reproductively sterile triploid individuals have been used for field trials. Genetic concerns have been raised regarding the proposed introduction. There is a need to assess genetic variation within and among native C. ariakensis, determine genetic relationships between existing U.S. hatchery stocks and native populations, and monitor the amount of genetic variation in hatchery populations. In addition, recent studies have revealed that it is very difficult, and indeed often impossible to discriminate among the many species of Crassostrea sympatric with C. ariakensis using morphological features. In fact, a newly described species, Crassostrea hongkongensis, is commonly found to coexist with C. ariakensis in southern China, and, as determined by molecular genetic identification of samples collected for broodstocks and research purposes, these two species are often confused. The genetic research presented here includes a comprehensive study of genetic variability within and among the hatchery stocks in the U.S. and wild populations in Asia using a novel set of microsatellite markers developed specifically for C. ariakensis. In addition, a laboratory hybridization trial was conducted for C. ariakensis and C. hongkongensis, as there are questions regarding the species status of these two taxa. In the hybridization trials, semi gametic incompatibility was observed between C. ariakensis and C. hongkongensis, indicating a partial reproductive isolation between these two taxa. In addition, an order of magnitude higher genetic divergence was observed between these two taxa compared with that found within each taxon based on analyses with three microsatellite markers. The results from the molecular marker analyses, coupled with additional genetic data indicating low transferability of C. ariakensis microsatellite loci to C. hongkongensis and detection of no natural hybrids in samples comprised of thousands of oysters, were consistent with previous sequence phylogeny studies and support the distinct species status of C. ariakensis and C. hongkongensis. . Analysis of C. ariakensis wild populations from the coast of Japan, South Korea, and China based on polymorphisms at eight microsatellite loci found a small but significant genetic differentiation among them, which could be characterized by a genetic pattern of isolation by distance. Eight genetically differentiated populations were further identified across the distribution range of C. ariakensis confirmed to date. Genetic differentiation among five hatchery stocks in the U.S. was five-fold larger than that observed among wild populations in Asia. In addition, significant reduction in genetic diversity compared to wild source populations was observed in these five hatchery stocks, indicating a genetic bottleneck in the stocks. Two mature stocks (TUI and WCA), isolated from their wild source population over 30 yrs, showed greater reduction in allelic diversity (60%) and a significant decrease in heterozygosities (11%--26%) compared to their wild source population, whereas three recent stocks (NCA, SCA99 and SCA00) showed less severe allelic diversity reduction (18%--30%) and nonsignificant change in levels of heterozygosities. These microsatellite markers have proven useful for genetically tracking the origins of C. ariakensis that might be introduced to Chesapeake Bay, particularly for animals originating from hatchery stocks.

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