The effects of feeding Karlodinium veneficum (PLY # 103; Gymnodinium veneficum Ballantine) to the blue mussel Mytilus edulis

The effects of exposure to the type species for Karlodinium veneficum (PLY # 103) on immune function and histopathology in the blue mussel Mytilus edulis were investigated. Mussels from Whitsand Bay, Cornwall (UK) were exposed to K. veneficum (PLY # 103) for 3 and 6 days. Assays for immune function included total and differential cells counts, phagocytosis and release of extra cellular reactive oxygen species. Histology was carried out on digestive gland and mantle tissues. The toxin cell quota for K. veneficum (PLY # 103) was measured by liquid chromatography–mass spectrometry detecting two separable toxins KvTx1 (11.6 ± 5.4 ng/ml) and KvTx2 (47.7 ± 4.2 ng/ml). There were significant effects of K. veneficum exposure with increasing phagocytosis and release of reactive oxygen species following 6 days exposure. There were no significant effects on total cell counts. However, differential cell counts did show significant effects after 3 days exposure to the toxic alga. All mussels produced faeces but not pseudofaeces indicating that algae were not rejected prior to ingestion. Digestive glands showed ingestion of the algae and hemocyte infiltration after 3 days of exposure, whereas mantle tissue did not show differences between treatments. As the effects of K. veneficum were not observed in the mantle tissue it can be hypothesized that the algal concentration was not high enough, or exposure long enough, to affect all the tissues. Despite being in culture for more than 50 years the original K. veneficum isolate obtained by Mary Parke still showed toxic effects on mussels.     

Impact of suspended mussels (Mytilus edulis L.) on plankton communities in a Magdalen Islands lagoon (Québec, Canada): A mesocosm approach

The Grande-Entrée Lagoon (Magdalen Islands, Canada) has supported mussel (Mytilus edulis) cultivation for the last 25 years. Algal biomass in this lagoon is relatively low while heterotrophic plankton biomass is high. Although often considered herbivorous, it is known that filter-feeding bivalves can consume various types of food, from bacteria to zooplankton. We hypothesize that along with phytoplankton, heterotrophs constitute an important food resource for the Grande-Entrée mussels. In situ mesocosm experiments were undertaken at different seasons using short socks filled with mussels from the same cohort taken from an aquaculture farm, in order to determine the impact of cultured mussels on local plankton communities and assess the role of heterotrophs. Filtration activity by the mussels and associated epibionts present in the socks was expressed as clearance rates (CR). The average CR over all taxa was lowest in June and highest in October. Diatoms, dinoflagellates and heterotrophic protists constituted the bulk of planktonic carbon removed by mussels. While smaller-sized taxa contributed little (< 5%) to mussel carbon intake, large-sized heterotrophs (namely ciliates) contributed 69 to 88%. Taxon-marker pigment analyses generally confirmed these observations for groups containing phototrophic pigments. The high heterotrophic biomass retained by mussels indicates they are a major food source for mussels in this environment and should be considered both in the evaluation of mussel feeding and in assessing the influence of cultured mussels on local plankton ecosystems.     

Timing of juvenile emergence from host mussels in the Japanese rosy bitterling, <Emphasis Type="Italic">Rhodeus ocellatus kurumeus</Emphasis>

The diel rhythm of juvenile emergence from host mussels in the Japanese rosy bitterling, Rhodeus ocellatus kurumeus, was investigated in a small pond in Osaka prefecture, Japan. The emergence of juvenile bitterling from host mussels occurred principally at night, with a peak in the early part of the night. The pattern of juvenile bitterling emergence was discussed in the context of an adaptive response to diurnal predation.     

Initial response of understorey vegetation to fire severity and salvage‐logging in the southern boreal forest of Québec

Abstract. In this study we compared the effects of fire on understorey vegetation in the Québec southern boreal forest with effects of salvage‐logging (clear‐cutting after fire). All 61 400‐m² sampling sites were controlled for overstorey composition (Deciduous, Mixed and Coniferous) and disturbance type, which consisted of three fire impact severity (FIS) classes (Light, Moderate and Extreme) and two harvesting techniques (Stem‐only and Whole‐tree Harvesting). Percent‐cover data of vegetation and post‐disturbance environmental characteristics were recorded in the field during the first two years after fire as well as soil texture. Ordination of fire alone demonstrated that, on Coniferous sites, fire initiates a succession whereby the understorey Coniferous sites approaches that of Deciduous‐Mixed sites, due to the release of the understorey from Sphagnum spp. dominance, this pattern being a function of FIS. On Deciduous‐Mixed stands, increased FIS resulted in a transition from herb to shrub dominance. Ordination of all five disturbance types showed that the impact of salvage‐logging on understorey composition was within the range of fire, but marginalized to the extreme end of the FIS spectrum. Variance partitioning demonstrated that overstorey and soil texture were the most important explanatory variables of fire alone, while disturbance type explained the largest independent fraction of understorey variation when salvage‐logging was introduced. Salvage‐logging also results in significant reductions in understorey abundance, richness and diversity, while indicator species analysis suggests that it favours mesoxerophytic to xeric species. Results are interpreted in light of shade‐tolerance dynamics, forest floor disturbance and soil moisture regimes. Implications for sustainable forest management are discussed.     

Experimental test of biodeposition and ammonium excretion from blue mussels (Mytilus edulis) on eelgrass (Zostera marina) performance

Blue mussels and eelgrass have been found to coexist in many locations. However, knowledge of the interactions between these species is limited. Two experiments were conducted in the laboratory, a “Deposit” and an “Epiphyte” experiment. The Deposit experiment examined possible effects of increasing load of blue mussel (Mytilus edulis) biodeposits on sediment biogeochemistry and eelgrass (Zostera marina) performance. Z. marina mesocosms received normal or high loads of mussel biodeposits (Normal and High), while no biodeposits were added to the Control. High dosage had overall negative effects on Z. marina, which was reflected as lower leaf numbers and biomass and accumulation of elemental sulphur in rhizomes. The sediment biogeochemical conditions were altered, as the mussel biodeposits enhanced sulphate reduction rates and increased sulphide concentrations in the porewater, which may result in sulphide invasion and reduced growth of Z. marina.In the Epiphyte experiment effects of mussel excretion, with particular emphasis on ammonium, on the growth of Z. marina and their epiphytes were examined. A thick cover of epiphytes developed on Z. marina growing together with M. edulis, and the relative growth rate was reduced with 20% compared to plants from control without mussels. Overall the experiments showed negative effects on Z. marina growing together with M. edulis, thereby supporting a preceding field study by Vinther et al. [Vinther, H.F., Laursen, J.S., Holmer, M. 2008. Negative effects of blue mussel (Mytilus edulis) presence in eelgrass (Zostera marina) beds in Flensborg fjord, Denmark. Est. Coast Shelf. Sci. 77, 91-103.].     

Spatial Structure of the Insect Community of a Small Dimictic Lake in the Laurentians (Québec)

The distribution of merolimnic benthic insects was studied in Lake Cromwell, a small (9 ha) and shallow (max. depth 9 m) dimictic lake with a summer hypolimnetic warming on the Laurentian highlands of Québec. Communities were described from 22 sets of emergence data. Two hundred and twelve species were recognized of which 153 were Chironomidae (Diptera). Through clustering and ordination techniques, five communities were recognized: one in the flooded shrub zone along the shore, two littoral, one sublittoral and one profundal. Differences between the communities were more quantitative than qualitative. The majority of species inhabited the shore and littoral stations, and only the hardiest reached the deepest zone. There were few species characteristic of the profundal, none of them abundant. Discriminating, dominant, and characteristic species were determined for each community, as were the ubiquitous species. There is a general decrease in species richness, species diversity and population density, and a change in community structure along the depth gradient. A discontinuity at 1–2 m is related to a sharp increase in Chaoboridae in the deeper waters.     

Eating Behaviors and Indexes of Body Composition in Men and Women from the Québec Family Study

Objective: To put into relationship the dietary and anthropometric profile of men and women with their eating behaviors (cognitive dietary restraint, disinhibition, and susceptibility to hunger) and to assess whether gender and obesity status influence these associations. Research Methods and Procedures: Anthropometric measurements (including visceral adipose tissue accumulation), dietary profile (3‐day food record), and eating behaviors (Three‐Factor Eating Questionnaire) were determined in a sample of 244 men and 352 women. Results: Women had significantly higher cognitive dietary restraint and disinhibition scores than men (p < 0.0001). In both genders, scores for disinhibition and susceptibility to hunger, but not for cognitive dietary restraint, were higher in obese subjects than in overweight and nonobese subjects (p < 0.05). Positive correlations were observed between rigid restraint and most of the anthropometric variables studied (0.12 ≤ r ≤ 0.16). Moreover, in women, flexible restraint was negatively associated with body fat and waist circumference (r = ?0.11). Cognitive dietary restraint and rigid restraint were positively related to BMI among nonobese women (0.19 ≤ r ≤ 0.20), whereas in obese men, cognitive dietary restraint and flexible restraint tended to be negatively correlated with BMI (?0.20 ≤ r ≤ ?0.22; p = 0.10). Discussion: Gender could mediate associations observed between eating behaviors and anthropometric profile. It was also found that disinhibition and susceptibility to hunger are positively associated with the level of obesity. On the other hand, cognitive dietary restraint is not consistently related to body weight and adiposity, whereas rigid and flexible restraint are oppositely associated to obesity status, which suggests that it is important to differentiate the subscales of cognitive dietary restraint. Finally, counseling aimed at coping with disinhibition and susceptibility to hunger could be of benefit for the long‐term treatment of obesity.     

Phytoplankton composition of the Kandalaksha Gulf, Russian White Sea: Dinophysis and lipophilic toxins in the blue mussel (Mytilus edulis)

Dinophysis acuminata and D. norvegica were observed in plankton net samples during the summer of 2002 from the Kandalaksha Gulf in the White Sea (North European Russia). Prorocentrum lima was found as an epiphyte on subtidal macroalgae in August, but not observed in plankton net samples. Protein phosphatase 2A (PP2A) inhibition measured 127.8 ng OA-equivalent/g of mussel (Mytilus edulis) hepatopancreas from samples collected a few days after when Dinophysis was recorded at a density of 1550 cells L⁻¹. Liquid chromatography–mass spectrometry confirmed presence of several classes of lipophilic shellfish toxins associated with Dinophysis spp. in the mussels including okadaic acid, dinophysistoxin-1, pectenotoxins and yessotoxins. No azaspiracid was detected. This represents the first identification of phycotoxicity in the White Sea.     

Putative neoplastic disorders in mussels (Mytilus edulis) from Southern Vancouver Island waters,British Columbia

Histologic examination of wild populations of Mytilus edulis in Saanich Inlet, British Columbia, Canada, revealed the presence of a highly invasive neoplasm. Two types of neoplasms were recognized; most were of hematopoietic origin, except in one mussel which had a presumptive gonadal neoplasm. Both types were apparently malignant neoplasms, based on their anaplastic appearance, invasiveness, mitotic activity, and associated tissue necrosis. This condition was observed from what is believed to be the earliest stage of the disease to the terminal stage, in which the connective tissue was almost completely replaced.     

Assessing the potential benthic-pelagic coupling in episodic blue mussel (Mytilus edulis) settlement events within eelgrass (Zostera marina) communities

Coastal marine seagrass ecosystems are important nursery grounds for commercially and recreationally important species, and they serve as key settlement and recruitment sites for other species. We investigated several years (2001-2003) where episodic settlement events of blue mussels (Mytilus edulis) occurred in Barnegat Bay, NJ, USA. Population assessment indicated that blue mussels settled in eelgrass beds (Zostera marina) in late spring with peak densities exceeding 170,000 m⁻². Based on calculated filtration rates of M. edulis, we determined that for at least 53 days in 2001, the density and size distribution of M. edulis were sufficient to filter the water column volume in excess of twice a day, with maximum calculated filtration rates exceeding 8 m³ water m⁻² day⁻¹. While the settlement event in 2001 was very localized, in 2003, the settlement event was considerably more widespread throughout the bay, with maximum settling densities exceeding 175,000 individuals m⁻². Associated with these high densities, maximum calculated filtration rates exceeded 15 m³ water m⁻² day⁻¹. This filtration potential may have impeded the localized development of a brown-tide (Aureococcus anophagefferens) bloom in 2001, which occurred in other regions of the bay, but the widespread settlement event seen in 2003 may have impeded the development of any brown-tide blooms in Barnegat Bay during that summer. The decline in mussel densities throughout the summer may be a result of elevated water temperatures in this back bay, but at one site, the high settlement of M. edulis was followed by a substantial migration (>40 individuals m⁻²) of small sea stars (Asterias forbesii). In 2001, A. forbesii was a significant factor in reducing M. edulis density by the end of the summer at the Barnegat Inlet site and a community level assessment showed significant positive correlations between mussel aggregations and sea star densities (r=0.68-0.73, P<0.001). At this same site in 2003, the sea stars were again present in high densities (26 m⁻²) and were a potential mechanism for mussel decline. In other regions of the bay, sea star densities are very low, but numerous other predatory species exist, including blue crabs (Callinectes sapidus), green crabs (Carcinus maenus), spider crabs (Libinia spp.), and several Xanthid crabs. Given the high mussel densities seen in this study and the considerable predation by sea stars and other benthic predators, the benthic-pelagic coupling which these mussels provide in this system contributes to the high secondary production in these grass beds.     

Gut Colonization by an Ice Nucleation Active Bacterium,Erwinia(Pantoea)ananasReduces the Cold Hardiness of Mulberry Pyralid Larvae

To evaluate the suitability of using ice nucleation active (INA) bacteria for the biological control of insect pests, the supercooling point (SCP) of larvae of mulberry pyralid,Glyphodes duplicalis,and silkworm,Bombyx mori,ingesting INA strains ofErwinia(Pantoea)ananasandPseudomonas syringaewas determined. Mean SCP of the guts of silkworm larvae ingesting INA strains ofE. ananasranged from −2.5 to −2.8°C, being 5°C higher than that in control treatments. Similarly, mean SCP of mulberry pyralid larvae ingesting INA strain ofE. ananas,which can grow well in the gut, was −4.7°C at 3 days after treatment, being 6.5°C higher than that in control treatments. On the other hand, mean SCP of the larvae-ingesting INA strain ofP. syringae,which cannot grow in the gut, was −9.0°C at 3 days after treatment, rising by only 2.5°C higher than that in the control treatments. In addition, more than 80% of the larvae of mulberry pyralid ingesting the INA strain ofE. ananasfroze and eventually died when exposed to −6°C for 18 h, while only 36% of the larvae ingesting the INA strain ofP. syringae,or approximately 20% of the control larvae, froze and died. Thus, the gut colonization by INA strains ofE. ananasreduced remarkably the cold hardiness of the insects. These findings suggest that INA strains ofE. ananascould be effective as a potential biological control agent of insect pests.     

松突圆蚧种群耐寒性的季节变化

采用过冷却点、低温暴露死亡率、冷识别温度和致死中低温累积等指标评价不同季节松突圆蚧的耐寒性.结果表明:各季节松突圆蚧的过冷却点波动在-22.4～-3.1 ℃之间,以冬季雌成虫的平均过冷却点最低(-14.83 ℃),显著低于夏季雌成虫、冬季1龄若虫和初孵若虫(P＜0.01),但其它发育阶段在冬、夏季之间均无显著差异;冬季1龄若虫、2龄性分化前若虫、2龄性分化后雄若虫、雌成虫和种群总体在-20～0 ℃下的死亡率、冷识别温度和致死中低温累积均明显低于夏季;1龄若虫、2龄性分化后雄若虫和种群总体的致死中低温累积与季节性平均气温均呈显著正相关(R＞R0.05=0.950,n-2=2),但各发育阶段的过冷却点与其致死中低温累积的相关性均未达显著水平.松突圆蚧冬季种群耐寒性最强,夏季种群最弱;该虫耐寒性的这一季节适应性并不依赖于过冷却点,而与气温的季节变化密切相关.     

Detecting freeze injury and seasonal cold-hardening of cells and tissues in the gall fly larvae, Eurosta solidaginis (Diptera: Tephritidae) using fluorescent vital dyes

This study identified a hierarchy in levels of cold tolerance for diverse tissues from larvae of Eurosta solidaginis. Following freezing at -80 degrees C, larval survival and the viability of specific tissues were assessed using membrane-permeant DNA stain (SYBY-14) and propidium iodide.Integumentary muscle, hemocytes, tracheae, and the crystal-containing portion of the Malpighian tubules were most susceptible to freezing injury. A second group consisting of fat body, salivary glands, and the proximal region of the Malpighian tubules were intermediate in their susceptibility, while the foregut, midgut, and hindgut were the most resistant to freezing injury. Seasonal increases in larval cold tolerance were closely matched by changes in the cold tolerance of individual tissues. Compared to larvae collected in September, the survival rates for each of the six tissues tested from October-collected larvae increased by 20-30%. The survival rate in all tissues was notably higher than that of whole animals, indicating that larval death could not be explained by the mortality in any of the tissues we tested. This method will be useful for assessing the nature of chilling/freezing injury, the role cryoprotectants, and cellular changes promoting cold tolerance.     

The influence of environmental factors on the morphology of red‐backed voles Myodes gapperi (Rodentia,Arvicolinae) in Québec and western Labrador

Geographical patterns of morphological variation in small mammals are often associated with environmental factors. The southern red‐backed vole Myodes gapperi is a widespread and abundant small mammal in Canada, occurring in environments as diverse as mixed‐wood forests and taiga. First upper molars and skulls from nine populations of southern red‐backed voles distributed across three ecozones and approximately 10° of latitude were analysed by means of geometric morphometric techniques, and their relationships with environmental variables were examined. A weak, non‐linear trend of size increase towards higher latitudes was observed in voles' skulls. Environmental variables appeared to be important drivers of shape differentiation among populations from the three distinct ecozones analysed. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 204–218.     

Prey selection and the functional response of sea stars (Asterias vulgaris Verrill) and rock crabs (Cancer irroratus Say) preying on juvenile sea scallops (Placopecten magellanicus (Gmelin)) and blue mussels (Mytilus edulis Linnaeus)

Predators in nature include an array of prey types in their diet, and often select certain types over others. We examined (i) prey selection by sea stars (Asterias vulgaris) and rock crabs (Cancer irroratus) when offered two prey types, juvenile sea scallops (Placopecten magellanicus) and blue mussels (Mytilus edulis), and (ii) the effect of prey density on predation, prey selection, and component behaviours. We quantified predation rates, behavioural components (proportion of time spent searching for prey, encounter probabilities) and various prey characteristics (shell strength, energy content per prey, handling time per prey) to identify mechanisms underlying predation patterns and to assess the contribution of active and passive prey selection to observed selection of prey. Sea stars strongly selected mussels over scallops, resulting from both active and passive selection. Active selection was associated with the probability of attack upon encounter; it was higher on mussels than on scallops. The probability of capture upon attack, associated with passive selection, was higher for mussels than for scallops, since mussels can not swim to escape predators. Sea stars consumed few scallops when mussels were present, and so did not have a functional response on scallops (the target prey). Rock crabs exhibited prey switching: they selected mussels when scallop density was very low, did not select a certain prey type when scallop density was intermediate, and selected scallops when scallop density was high relative to mussel density. The interplay between encounter rate (associated with passive selection) and probability of consumption upon capture (associated with both active and passive selection) explained observed selection by crabs. Scallops were encountered by crabs relatively more often and/or mussels less often than expected from random movements of animals at all scallop densities. However, the probability of consumption varied with scallop density: it was lower for scallops than mussels at low and intermediate scallop densities, but tended to be higher for scallops than mussels at high scallop densities. When mussels were absent, crabs did not have a functional response on scallops, but rather were at the plateau of the response. When mussels were present with scallops at relatively low density, crabs exhibited a type II functional response on scallops. Our results have implications for the provision of protective refuges for species of interest (i.e., scallops) released onto the sea bed, such as in population enhancement operations and bottom aquaculture.     

Differences in pupal cold hardiness and larval food consumption between overwintering and non‐overwintering generations of the common yellow swallowtail,Papilio machaon (Lepidoptera: Papilionidae), from the Osaka population

To clarify differences in pupal cold hardiness and larval food consumption between overwintering and non‐overwintering generations of the common yellow swallowtail, Papilio machaon, we reared larvae from the Osaka population under photoperiods of 16 h light : 8 h dark (LD 16:8) (long day) or LD 12:12 (short day) at 20°C. We examined the relationship between food consumption and weight during the final larval stadium and pupae, and measured the pupal supercooling point (SCP). Although the ratio of assimilation to consumption did not differ significantly between photoperiods, the ratio of assimilation to pupal weight differed significantly between individuals reared under long and short days. All diapausing pupae were brown, whereas 56% of non‐diapausing pupae were green with the remainder brown. The mean pupal body length (L), dorsal width (W₁) and lateral width (W₂) were larger in non‐diapausing than in diapausing pupae, and the W₁/L and W₁/W₂ ratios differed significantly between non‐diapausing and diapausing pupae. SCP was approximately –20°C and did not differ among pupae 5, 15 and 30 days after pupation under long‐day conditions. However, under short‐day conditions, mean SCP gradually decreased, stabilizing at approximately –24 to –25°C by 30 days after pupation. After freezing, some diapausing pupae emerged as adults, whereas all non‐diapausing pupae died. Both egestion and assimilation were greater under long‐day conditions. The results revealed that pupae of this papilionid exhibit seasonal polyphenism in physiological and morphological traits. Energy from food appears to be expended on increasing cold hardiness in the overwintering generation and on reproduction in the non‐overwintering generation.     

The respiratory capacity of marine mussels (Mytilus galloprovincialis) in relation to the high temperature threshold

Thermal tolerance limits of ectotherms may result from respiratory limitations. In response to declining oxygen availability, organisms have shown to exhibit oxyregulation by enhancing ventilation and heartbeat rates. In this study we examined how this regulatory response in mussels (Mytilus) changes with increasing temperature. Experimental mussels showed extensive oxyregulation at temperatures near to their habitat temperature, but increasingly lost this capacity towards higher temperatures. At breakpoint temperature no regulation took place and respiration rates changed proportional to oxygen availability. These results revealed how thermal limitations relate to respiratory capacity of mussels.     

The effect of size and age on depuration rates of diarrhetic shellfish toxins (DST) in mussels (Mytilus edulis L.)

Depuration or elimination of diarrhetic shellfish toxins (DST) was followed for 73 days in 1- and 2-year-old mussels. The age groups also differed in size, providing a broad approach to studying the effect of the differences in physiology accompanying the differences in size. Content of DST was analysed both on groups and individual mussels. Environmental variables were measured to evaluate their effect on depuration.We found no significant differences in elimination rate of DST between 1- and 2-year-old mussels under natural conditions. This suggests that size and age do not affect the elimination rate of the DST. The present study is the first study on the effect of age and size on the elimination rate of algal toxins in bivalves. The natural variations in food levels and temperature were not found to affect the elimination rate of DST.The digestive gland weights in the 1-year-old mussels increased four times while the DST content per individual decreased eight times. This demonstrated that dilution of toxins due to tissue growth could have an important contribution to declines in toxin concentrations. Changes in tissue mass are affected by environmental variables via growth or starvation, and when such changes lead to concentration or dilution of toxins this does not reflect the accumulation or removal of toxins from the tissues. We hence suggest that when evaluating the actual elimination capacity of the mussels, as in the present study, the total content of toxins per individual should be used, rather than toxin concentrations.The 1-year-old mussels had faster growth compared to the 2-year-old mussels in both total soft tissue and digestive glands. The mechanism of DST elimination is still unknown. If this process involves metabolism of the toxins, one could expect the rates of elimination to follow overall metabolic rates. However, the results from the present study suggest that large differences in growth rates, which also include difference in feeding and metabolic rates, do not affect the elimination rate of DST. Our results support the assumption that the depuration rates cannot be accelerated, even in artificial systems, as a cost-effective way to solve the problem with toxic mussels for the industry.     

Experimental exposure of the blue mussel (Mytilus edulis, L.) to the toxic dinoflagellate Alexandrium fundyense: Histopathology, immune responses, and recovery

Mussels (Mytilus edulis) were exposed to cultures of the toxic dinoflagellate Alexandrium fundyense or the non-toxic alga Rhodomonas sp. to evaluate the effects of the harmful alga on the mussels and to study recovery after discontinuation of the A. fundyense exposure. Mussels were exposed for 9 days to the different algae and then all were fed Rhodomonas sp. for 6 more days. Samples of hemolymph for hemocyte analyses and tissues for histology were collected before the exposure and periodically during exposure and recovery periods.Mussels filtered and ingested both microalgal cultures, producing fecal pellets containing degraded, partially degraded, and intact cells of both algae. Mussels exposed to A. fundyense had an inflammatory response consisting of degranulation and diapedesis of hemocytes into the alimentary canal and, as the exposure continued, hemocyte migration into the connective tissue between the gonadal follicles. Evidence of lipid peroxidation, similar to the detoxification pathway described for various xenobiotics, was found; insoluble lipofuchsin granules formed (ceroidosis), and hemocytes carried the granules to the alimentary canal, thus eliminating putative dinoflagellate toxins in feces. As the number of circulating hemocytes in A. fundyense-exposed mussels became depleted, mussels were immunocompromised, and pathological changes followed, i.e., increased prevalences of ceroidosis and trematodes after 9 days of exposure. Moreover, the total number of pathological changes increased from the beginning of the exposure until the last day (day 9). After 6 days of the exposure, mussels in one of the three tanks exposed to A. fundyense mass spawned; these mussels showed more severe effects of the toxic algae than non-spawning mussels exposed to A. fundyense.No significant differences were found between the two treatments during the recovery period, indicating rapid homeostatic processes in tissues and circulating hemocytes.     

Determination of the maximum and minimum lethal temperatures (LT50) for Loxosceles intermedia Mello-Leitão, 1934 and L. laeta (Nicolet, 1849) (Araneae, Sicariidae)

In this study, the maximum and minimum lethal temperatures (LT₅₀) of L. intermedia and L. laeta were determined in two treatments: gradual heating (25–50°C) and cooling (25°C to −5°C), and 1 h at a constant temperature. In gradual temperatures change, L. intermedia mortality started at 40°C and the LT₅₀ was 42°C; for L. laeta, mortality began at 35°C and the LT₅₀ was 40°C. At low temperatures, mortality was registered only at −5°C for both species. In the constant temperature L. intermedia showed a maximum LT₅₀ at 35°C and L. laeta at 32°C; the minimum LT for both species was −7°C.