Hyalophysa lynni n. sp. (Ciliophora,Apostomatida), a new pathogenic ciliate and causative agent of shrimp black gill in penaeid shrimp

The parasitic ciliate causing shrimp black gill (sBG) infections in penaeid shrimp has been identified. The sBG ciliate has a unique life cycle that includes an encysted divisional stage on the host’s gills. The ciliature of the encysted trophont stage has been determined and is quite similar to that of the closely related apostomes Hyalophysa bradburyae and H. chattoni. Hyalophysa bradburyae is a commensal ciliate associated with freshwater caridean shrimp and crayfish, while H. chattoni is a common commensal found on North American marine decapods. Based on 18S rRNA gene sequence comparisons, the sBG ciliate is more closely related to the marine species H. chattoni than to the freshwater species H. bradburyae. The unique life cycle, morphology, 18S rRNA gene sequence, hosts, location, and pathology of the sBG ciliate distinguish this organism as a new species, Hyalophysa lynni n. sp.     

The complete life cycle of the unusual apostome Hyalophysa clampi (Ciliophora,Apostomatida), a symbiont of crayfish in Alabama (USA)

Hyalophysa clampi Browning and Landers, 2012 was reexamined to determine all stages in the life cycle of this symbiotic ciliate. The cell feeds as a normal exuviotroph within the exoskeleton of its molted crayfish host but does not encyst following the trophont stage. Trophonts transform into swimming tomont stages, which divide by palintomy over successive divisions, splitting to two cells, separating, and repeating. The divisions cease when the daughter cells attain the size of the infestive tomite stage, which attaches to a new crayfish. This unique life cycle is most similar to the European hermit crab symbiont Polyspira delagei, which forms chains of daughter cells during division. Scanning electron microscopy confirmed the unusual presence of two contractile vacuoles in H. clampi, unique among the Apostomatida, and provided ultrastructural details to better understand light microscopy silver staining. The genus diagnosis for Hyalophysa is modified herein to accommodate this new life cycle.     

Ultrastructure of the eyes of the grass shrimp,Palaemonetes pugio

Summary The cone cells and corneagenous cells possess extensive networks of smooth tubular endoplasmic reticulum that may be involved in optical reflectance and light-adaptational responses, respectively. The extracellular basal lamina of the basement membrane is confluent with glial cell capillary walls and may prove to be a viaduct for the transmission of hemolymph-borne substances to the retina or of retinal degradation products to the hemolymph. In addition to dense pigment granules, the distal pigment cells are shown for the first time to contain migratory reflecting platelets that are usually polymorphic in light-adapted eyes but are rectangular in dark-adapted eyes. In the latter these plates become aligned against the crystalline cones and presumably contribute to the reflection superposition optics of the grass shrimp. Dark-adapted retinular cells possess well-developed perirhabdomal cisternae, oblong or ovoid mitochondria, generally vesicular rough endoplasmic reticulum, and occasional, spherical, calcium-like intrarhabdomal inclusions. Light-adapted retinular cells possess poorly developed perirhabdomal cisternae, lamelliform rough endoplasmic reticulum, and condensed mitochondria frequently associated with lipid droplets and pigment granules. The cytoplasmic boundaries of the reflecting pigment cells expand into the extracellular spaces between individual ommatidial retinular cells during dark adaptation and recede to the interommatidial extracellular spaces during light adaptation. Cytoplasmic microfilament bundles found only at the bases of partially light-adapted rhabdomeric microvilli may be involved in microvillar shortening.     

Some factors affecting size distribution and density of grass shrimp (Palaemonetes pugio) populations in two New Jersey estuaries

Mature Palaemonetes pugio, from a polluted estuary, Piles Creek (PC) are larger than those in a more pristine estuary in Tuckerton (TK). Possible causes for the differences in size-structure could be differences in environmental factors at the two creeks, differential competition at the two sites, inherent factors causing a greater growth rate in the PC population, differences in reproductive timing, or differential predation at the two sites. Lab microcosm studies were used to examine the possibility of inherent population differences or environmental conditions (including differences in salinity) causing faster growth in PC. There was no evidence that PC shrimp grew faster than TK shrimp, nor that PC conditions fostered greater growth compared to TK. Salinity adjustments in PC and TK tanks also had no effect on growth. Therefore, it appears that genetic and environmental factors did not play a significant role in greater shrimp growth in PC. In the field, data on relative abundances of Fundulus heteroclitus and P. pugio, and size-frequency distributions of P. pugio were collected from the two estuaries. Gravid females and recruits of young shrimp physically appeared at approximately the same time within both systems, eliminating earlier reproduction as a cause of the size discrepancy. There were three times as many shrimp in PC than in TK (eliminating the possibility of increased population density and competition at TK as a cause) and three times as many F. heteroclitus present in TK than in PC. Since it has already been established that the Fundulus at PC are smaller than at TK and that they are poor predators, differences in Fundulus predation would appear to be an important factor in determining the number and size-frequency of the grass shrimp.     

Lynnia grapsolytica n. gen,n. sp. (Ciliophora: Apostomatida: Colliniidae), a Deadly Blood Parasite of Crabs with a Novel Pseudocytopharynx

We describe a new genus and species of blood-dwelling apostome ciliate, Lynnia grapsolytica n. gen., n. sp. (Apostomatida: Colliniidae). A distinct kinety “hook” pattern on the tomite’s posterior ventral face, coupled with its marine habitat and use of a decapod host, readily distinguishes this ciliate from all known colliniids. We detected the parasite in ~12% of Pachygrapsus crassipes (Brachyura: Grapsidae) crabs in a California estuary and confirmed its presence at a Baja California rocky intertidal site. As existing methods failed to adequately stain this ciliate, we developed a new miniaturized silver carbonate impregnation staining method that produced excellent somatic and nuclear stains in all five observed cell types. A possibly unique trait is the active invagination of the tropho-tomont’s anterior to form a temporary “pseudocytopharynx,” likely used for feeding. Histological examination revealed that the ciliate invaded and damaged skeletal muscle, the heart, connective tissues, and gonads. Survivorship analysis indicated that infected crabs experienced 2.6 times greater daily mortality than uninfected crabs. Laboratory and field experimental infection attempts failed, suggesting a complex life cycle with outside-host development. Phylogenetic analysis at the 18S and COI loci confirmed the ciliate's placement in the Colliniidae. We emend the diagnosis of Family Colliniidae.     

Salinity tolerance of the copepod Apocyclops dengizicus (Lepeschkin, 1900), a key food chain organism in the Salton Sea,California

The copepod Apocyclops dengizicus is a key item in the food chain of the Salton Sea where the salinity is currently 45 g 1^–1. The salinity of the Salton Sea may reach 90 g 1 ^–1 within the next 20 years. This study examined the salinity tolerance of this copepod.Large copepodite and adult A. dengizicus were introduced into various salinities with and without acclimation. The 96 h LC₅₀ without acclimation was 101 g 1^–1. Mortality (at 96 h) without acclimation was low at salinities of 90 g 1 ^–1 or less.Copepod cultures were maintained, with successful reproduction of at least one new generation, at salinities of from 0.5 to 68 g 1 ^–1 for at least 120 days. Copepods maintained at higher salinities, up to 79 g 1 ^–1, remained alive up to 90 days, but a new generation was not produced. In laboratory studies of larval production and survivorship, few nauplii were released at salinities of 68 g 1 ^–1 or higher, and none survived to the copepodite stage.     

Rhabdom changes in the shrimp,Palaemonetes

The fine structure of the principal compound eye of the shrimp, Palaemonetes, was studied under conditions of light and dark adaptation. Ommatidium the situation in other decapod crustaceans. Light and dark adapted eyes differ in that the rhabdom changes its shape; morphological evidence suggests a possible sequence of events involving production, utilization, and degradation of photoreceptor membrane, a discontinuous process occurring only during changes from light to dark and dark to light. A hypothesis of membrane turnover is proposed.     

Effects of cyclic hypoxia on gene expression and reproduction in a grass shrimp, Palaemonetes pugio

Cyclic changes in dissolved oxygen occur naturally in shallow estuarine systems, yet little is known about the adaptations and responses of estuarine organisms to cyclic hypoxia. Here we examine the responses of Palaemonetes pugio, a species of grass shrimp, to cyclic hypoxia (1.5-8 mg/l dissolved oxygen; 4.20-22.42 kPa) at both the molecular and organismal levels. We measured alterations in gene expression in hepatopancreas tissue of female grass shrimp using custom cDNA macroarrays. After short-term (3-d) exposure to cyclic hypoxia, mitochondrial manganese superoxide dismutase (MnSOD) was upregulated and 70-kd heat shock proteins (HSP70) were downregulated. After 7-d exposure, nuclear genes encoding mitochondrial proteins (ribosomal protein S2, ATP synthase, very-long-chain specific acyl-CoA dehydrogenase [VLCAD]) were downregulated, whereas mitochondrial phosphoenol pyruvate carboxykinase (PEP Cbk) was upregulated. After 14 d, vitellogenin and apolipoprotein A1 were upregulated. Taken together, these changes suggest a shift in metabolism toward gluconeogenesis and lipid export. Long-term (77-d) exposure to hypoxia showed that profiles of gene expression returned to pre-exposure levels. These molecular responses differ markedly from those induced by chronic hypoxia. At the organismal level, cyclic hypoxia reduces the number of broods and eggs a female can produce. Demographic analysis showed a lower estimated rate of population growth in grass shrimp exposed to both continuous and short-term cyclic hypoxia, suggesting population-level impacts on grass shrimp.     

Salinity tolerance of Mytilocypris henricae (Chapman) (Crustacea,Ostracoda)

Salinity tolerance, and the effects of temperature upon it, of the Australian ostracod Mytilocypris henricae (Chapman) was determined in direct transfer experiments using adults. Animals were subjected to a combination of 11 salinities (ranging between 0.0 g · 1^–1 and 45.0 g · 1^–1) and 4 temperatures (10, 15, 20 and 25 °C). Survival was analysed using two statistical techniques: the logit linear model and the proportional hazards model. Results show that both salinity and temperature have a significant effect on survival, but there is no significant interaction between temperature and salinity.     

Salinity tolerance of the barbel,Barbus callensis Valenciennes, 1842 (Pisces,Cyprinidae) and its ecological significance

The lethal salinity limits (LC₅₀ and mean survival times) of two populations of barbel, Barbus callensis, were determined. Conditions in Lake Ichkeul, Tunisia, are lethal for the fish in summer; this explains their seasonal migrations into Oued Sejnane and the other tributaries. Tolerance increased between 1984 and 1985 from LC₅₀ = 15.6 to LC₅₀ = 17.2 in a population from Oued Mejerdah; this may be connected with the dissolution of rock salt in the new Sidi Salem reservoir.

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Résumé Les limites létales de salinité (CL₅₀ et durée moyenne de survie) de deux populations de barbeaux tunisiens ont été déterminées. Nous avons montré que les conditions de salinité dans le lac Ichkeul sont létales pour ces poissons en été, ce qui explique leurs migrations saisonnières vers l'oued Sejnane et les autres affluents. Nous avons aussi constaté une élévation récente de la tolérance de la population de la Mejerdah, qui peut être en relation avec la dissolution des roches salines dans le nouveau réservoir de Sidi Salem.

     

Salinity tolerance and osmoregulation in the freshwater crab,Barytelphusa guerini (Milne Edwards)

The freshwater crab, Barytelphusa guerini, tolerates gradual transfer to higher salinities upto seawater, regulating its blood chlorides fairly well. Its metabolic rate shows a minimum in 50% seawater and increases on either side, during dilution as well as during concentration of the medium. However, this increase is more pronounced in hypotonic than in hypertonic media.     

Kinetics and mechanism of tolerance induction on acclimation ofVillorita cyprinoides (Hanley) to copper and zinc

The typical euryhaline clamVillorita cyprinoides (Hanley) was acclimated to copper and zinc at salinity 13 × 10⁻³ and < 1 × 10⁻³ (fresh water). Acclimation enhanced the lethal tolerance, as denoted by dose-survival curves, which was more pronounced after zinc acclimation. In fresh water copper acclimation sensitized the organisms. The copper accumulation trend was significantly changed consequent to metal acclimation, especially after zinc acclimation, indicating some tissue metal regulatory effect. Acclimation to copper equiped the organism to survive for longer periods with increased body burden of copper, while zinc acclimation supressed the uptake of the more toxic ion copper. The earlier report of increased uptake of zinc by this organism during combined exposure with copper is corelated in the present context. The role of metallothionein like protein in providing protection against metal toxicity, the environmental implication of acclimation phenomena are indicated     

Behavior of estuarine dolphin, Sotalia guianensis (Cetacea, Delphinidae), in controlled boat traffic situation at southern coast of Rio Grande do Norte, Brazil

Dolphin/whale watching activity represents the major source of income to many local communities, however many studies describe negative effects of this activity on animals’ normal behavior. In this paper we describe a behavioral analysis of estuarine dolphins (Sotalia guianensis), proximity pattern and breathing synchrony during the first year after the delimitation of a coastal reserve and enforcement of rules to control boat traffic at southern Rio Grande do Norte (Brazil). Different from studies conducted before the delimitation of the coastal reserve, our results show that forage behavior did not decrease and overall activity budget did not change in the presence of boats, although animals would still increase proximity and breathing synchrony during the first semester. We conclude that simple rules for control of boat traffic are effective in minimizing the short term negative impacts on dolphins. However, the enforcement of common rules is a difficult compromise between community needs and vulnerability of dolphin populations.     

Effects of Microphallus turgidus (Trematoda: Microphallidae) on the predation, behavior, and swimming stamina of the grass shrimp Palaemonetes pugio

The effect of the trematode Microphallus turgidus on its second intermediate host, the grass shrimp, Palaemonetes pugio, was tested. To do so, we measured the susceptibility of infected and uninfected shrimp to predation by the mummichog, Fundulus heteroclitus. Shrimp behavior was compared in the presence and absence of a fish predator, and the swimming stamina and backthrust escape responses of infected and uninfected shrimp were measured. Infected shrimp were more likely to be eaten by a predator than uninfected shrimp, had lower swimming stamina, and spent more time swimming and less time motionless in the presence of a predator. There was no difference between backthrust distances traveled in response to a stimulus by either infected or uninfected shrimp. Thus, M. turgidus may increase the predation of P. pugio in the wild, possibly by affecting the swimming stamina and predator avoidance responses of the shrimp.     

Rosette glands in the gills of the grass shrimp,Palaemonetes pugio. I. Comparative morphology,cyclical activity,and innervation

Two types of exocrine rosette glands (called type A and type B), located in the gill axes of the grass shrimp Palaemonetes pugio, are described. The type A glands are embedded within the longitudinal median septum of the gill axes, whereas the type B glands typically project into the efferent hemolymph channels of the gill axes. Although both glands have certain common characteristics (i.e., a variable number of radially arranged secretory cells, a central intercalary cell, and a canal cell that forms the cuticular ductule leading to the branchial surface), they differ in the following respects. The type B gland is innervated, but the type A gland is not; axonal processes, containing both granular (ca. 900–1300 Å) and agranular (ca. 450–640 Å) vesicles, occur at a juncture between adjacent secretory cells and the central cell of the type B gland. The secretory cells of type A and type B glands differ in their synthetic potential and membrane specializations. These differences are more pronounced in well-developed, mature glands, most frequently encountered in larger (24–28 mm, total length) grass shrimp, than in the underdeveloped, immature glands that are most abundant in smaller (14–18 mm, total length) grass shrimp. Thus, in mature glands, the secretory cells of the type A rosette glands are characterized by extensive RER, abundant Golgi, and numerous secretory granules, whereas the secretory cells of the type B gland are characterized by extensively infolded and interdigitated basal plasmalemmas and by the presence of numerous mitochondria. In general, both types of glands exhibit increased secretory activity soon after ecdysis. The central and canal cells in both glands seem to have a role in the modification of the secreted materials. The possible functions assigned to the type A gland and the type B gland include phenol-oxidase secretion and osmoregulation, respectively.     

Morphological description of three marine ciliates (Ciliophora, Scuticociliatia), with establishment of a new genus and two new species

Three marine scuticociliates, Falcicyclidium fangi nov. gen., nov. spec., Falcicyclidium atractodes nov. spec., and Cristigera media Kahl, 1928 were investigated using live observation and silver impregnation methods. The genus Falcicyclidium is distinguished by the combination of: (i) dorsoventrally flattened body, (ii) hook-like (falciform) paroral membrane, (iii) anterior end of paroral membrane posterior to anterior end of membranelle 1, and (iv) multiple caudal cilia. Falcicyclidium fangi nov. spec., the type of the new genus, can be recognized by the combination of its large size, extremely dorsoventrally flattened (3:1) body, consistently 10 somatic kineties, and the broad, elongate buccal area occupying 60% of the body length. Falcicyclidium atractodes nov. spec. is mainly characterized by a unique spine projecting from both the anterior and posterior end. The uncommon form, Cristigera media is redescribed based on the population from Qingdao, the statistic data and additional features, especially the morphology of the living cells, are documented.     

Prevalence of the bopyrid isopod Probopyrus pandalicola in the grass shrimp, Palaemonetes pugio, in four tidal creeks on the South Carolina-Georgia coast

The grass shrimp, Palaemonetes pugio, is an important food source for many invertebrate and fish species, including several of commercial importance. The bopyrid Probopyrus pandalicola prevents reproduction in P. pugio by sexual sterilization. The purpose of our research was to determine bopyrid prevalence in grass shrimp over the course of a year. Shrimp were collected from 2 estuarine systems in South Carolina and 2 estuarine systems in Georgia and examined for parasite presence, sex, and gravidity. Site-specific monthly prevalence ranged from 0 to 6.3%. Country Club Creek had the maximum mean +/- SE prevalence of 3.1 +/- 0.3%, and Harbour Town had the minimum of 1.3 +/- 0.3%. Maximum prevalence was concurrent with peak gravidity for Moon River; thus, at this site the negative effect of this parasite on reproductive output may be greater. Reduced egg production may affect grass shrimp abundance and ultimately the recruitment success of its predators.     

Morphology and infraciliature of Holosticha bradburyae nov. spec. (Ciliophora,Hypotrichida) from the Yellow Sea,China

The living morphology and infraciliature of a new marine hypotrichous ciliate, Holosticha bradburyae nov. spec., collected from the coastal water off Qingdao (Tsingtao), China, are investigated. This species is characterized by: body size 150–320 × 25–75 m with brownish to dark brown cell colour, ca. 53 adoral membranelles and 1 anteriorly positioned buccal cirrus; 3 frontal, 2 frontoterminal and 20–26 transverse cirri; midventral rows comprising 27-32 pairs of cirri; one conspicuous gap always present between anterior and posterior parts of AZM, and 2–5 distinctly elongated membranelles are always present at the posteriormost end; cortical granules conspicuous, round and flattened with central depression, arranged in about 10 lines on dorsal side; 28–33 irregularly arranged macronuclear nodules; 9–11 complete dorsal kineties; caudal cirri absent.