Differences in embryo production between sympatric species of mysids (family Mysidae) in the shallow coastal waters off Vancouver Island, BC

The ecological importance of mysid (Crustacea: Mysidacea) populations in coastal food webs is not well understood. Although the 10 or more species of epibenthic mysids found in Clayoquot Sound, BC, Canada, form the primary prey resource for seasonally abundant gray whales (Eschrichtius robustus), little is known about their life history. Here, Holmesmysis sculpta dominates multi-species swarms, however there are several potential routes to this state, one of which is higher embryo production. Reproductive capacity is key to the resiliency of local mysid populations and species diversity, in this study I compare one aspect, brood size for the four most commonly found species, H. sculpta, Neomysis rayii, Exacanthomysis davisi, and Columbiaemysis ignota. The number of embryos per brood was found to vary significantly between species; however, individual length is a stronger determinant of brood size. Here, I report previously unknown life history attributes of coastal mysid species, with important consequences for community structure and local marine food webs.     

The occurrence of defensive alkaloids in non-integumentary tissues of the Brazilian red-belly toad Melanophryniscus simplex (Bufonidae)

The red-belly toads (Melanophryniscus) of southern South America secrete defensive alkaloids from dermal granular glands. To date, all information on Melanophryniscus alkaloids has been obtained by extraction from either skins or whole organisms; however, in other amphibians, tetrodotoxins, samandarines, and bufadienolides have been detected in both skin and other organs, which raise the possibility that lipophilic alkaloids may occur in non-integumentary tissues in Melanophryniscus as well. To test this hypothesis, we studied the distribution of alkaloids in the skin, skeletal muscle, liver, and mature oocytes of the red-belly toad M. simplex from three localities in southern Brazil. Gas chromatography and mass spectrometry of skin extracts from 11 individuals of M. simplex resulted in the detection of 47 alkaloids (including isomers), 9 unclassified and 38 from 12 known structural classes. Each alkaloid that was present in the skin of an individual was also present in the same relative proportion in that individual??s skeletal muscle, liver, and oocytes. The most abundant and widely distributed alkaloids were the pumiliotoxins 251D, 267C, and 323A, 5,8-disubstituted indolizidines 207A and 223D, 5,6,8-trisubstituted indolizidine 231B, 3,5-disubstituted pyrrolizidines cis-223B and cis- and trans-251K, and izidine 211C. We report the first record of piperidines in Melanophryniscus, bringing the total number of alkaloid classes detected in this genus to 16. Alkaloid composition differed significantly among the three study sites. The functional significance of defensive chemicals in non-integumentary tissues is unknown.     

Supralittoral amphipod abundances across habitats on Mediterranean temperate beaches

Community complexity and abiotic conditions are key components of environmental heterogeneity that affect the abundance and distribution of species. In this study we evaluated how environmental conditions affect abundances of supralittoral amphipods (Talitridae) in four habitats (sandy beach, rivermouth, wrack and lakeshore), along the Italian peninsula in the Mediterranean Sea. All samplings covered a 12 month period, and used the same sampling methodology thereby enabling comparison of abundances and species composition and richness. Four species (Talitrus saltator (Montagu, 1808), Orchestia gammarellus (Pallas, 1766), O. montagui Audouin 1826, O. cf. cavimana Heller 1865) were collected in the different habitats, but most species were found or were abundant in only one of the four habitats. Abundances of talitrids (numbers per sampling hour) differed significantly among the habitats with highest abundances found in the wrack and on the riverbank in proximity to an estuary, and lowest abundances observed on four sandy beach sites. Environmental conditions (temperature, moisture, substrate penetrability) differed among the habitats and were associated with some of the among-site variability in abundances. Our findings demonstrate that talitrids thrive better in some supralittoral habitats than others, and that some habitats could be considered to be “hotspots” of talitrid ecology and biodiversity.     

Episodic targeting aggression and the histories of Lemur social groups

Summary Periodically, members of captive Lemur social groups target others for intense aggression. Over periods of several days, weeks, and sometimes months, one to three lemurs persistently follow and attack one or two particular group mates until the targets no longer associate with their group. Episodic targeting aggression is nonrandom with regard to time of year, group size and sex ratio, and the kinship, age, and gender of targets. The vast majority of episodes observed over the past 18 years at the Duke University Primate Center (DUPC) has occurred between like-sex adolescents and adults in conjunction with estrous cycling or infant births and most often after groups have reached apparent critical sizes. When unrelated adults have shared group membership, members of one family have almost invariably first targeted members of the other. In several groups, entire matrilines have gradually been evicted by members of another across periods of several years. When non-relatives have been absent, lemurs have evicted relatives that had previously formed separate subgroups. Episodic targeting aggression has been documented at the DUPC in over a dozen different social groups, comprising three different species. The phenomenon occurs repeatedly in groups held in a variety of large outdoor runs as well as in outdoor enclosures providing naturalistic space and physical structure. More-over, an appreciable number of recent observations in Madagascar suggest that the patterns we have documented well represent the phenomenon as it occurs in the wild. Targeting aggression based on group size, sex ratio, kinship and gender has been reported for no other primate taxon. We suggest that episodic targeting aggression reflects heretofore undescribed tactics in reproductive competition that may characterize many lemurid and indriid taxa. As such, the phenomenon has broad implications for the structure of lemur social groups and populations. Provisional models of the social dynamics and histories of Lemur social groups are presented for evaluation during upcoming field work.     

Transmission,plasticity and the molecular identification of cyanobacterial symbionts in the Red Sea sponge <Emphasis Type="Italic">Diacarnus erythraenus</Emphasis>

Cyanobacterial symbionts in the sponge Diacarnus erythraenus from the Red Sea were identified in both adult sponges and their larvae by 16S rDNA sequencing. A single cyanobacterial type was found in all samples. This cyanobacterial type is closely related to other sponge cyanobacterial symbionts. The cyanobacterial rDNA, together with the morphological analysis by electron and fluorescence microscopy, provided evidence for vertical transmission of the symbionts in this sponge. In addition, we show phenotypic plasticity of the symbionts inside the sponge, probably as a result of variability in light availability inside the sponge tissue. Finally, the reproduction of Diacarnus erythraenus is also described.Matan Oren, Laura Steindler have contributed equally to the work.     

Lead exposure in Saudi Arabia from the use of traditional cosmetics and medical remedies

Twenty Henna samples were collected and analysed for lead by electrothermal atomic absorption spectrophotometry after a microwave acid digestion procedure. The mean lead concentration was 5.50 g g^–1, with a range from 1.29 g g^–1 to 16.48 g g^–1. The data did not show a high concentration of lead in these samples. However, if we take into account the popular use of henna, the cumulative effects of prolonged exposure to low lead especially in children cannot be ruled out.     

Effects of movement and eating on chemosensory tongue-flicking and on labial-licking in the leopard gecko (Eublepharis macularius)

Summary Two forms of lingual protrusion, tongueflicking and labial-licking, were differentially affected by combinations of movement and eating conditions in a eublepharid gecko (Eublepharis macularius). Tongue-flicking, in which the tongue contacts substrates beyond the lizard's body, occurred at increased rates during locomotion and during locomotion was significantly more frequent after eating than in a baseline condition. Labial-licking, in which a protruded portion of the tongue touches the labial, mental or rostral scales that surround the mouth, increased after eating. Unlike tongue-flick rates, by far the highest labial-lick rates were observed in stationary lizards after eating. The elevated tongue-flicking rates during movement after eating may be a manifestation of a postingestive chemosensory search for prey. In addition to grooming, several possible chemosensory functions of labial-licking are discussed, including gustatory sampling, sampling prey chemicals on the labials for transfer to the vomeronasal system, and redistribution of chemicals on the tongue to enhance transfer. It is suggested that labial-licking might help motionless lizards maintain vigilance for visual prey stimuli associated with the specific chemical prey cues. Another possible explanation for the increased labial-lick rate while motionless after eating is that prey chemicals induce tongue-flicking, but that the distance protruded is lessened and the tongue does not contact environmental substrates. Tongue-flicking while stationary is unlikely to lead to detection of additional prey and might incur detection by the lizard's predators or prey.     

Suppressing antagonistic bioengineering feedbacks doubles restoration success

In a seagrass restoration project, we explored the potential for enhancing the restoration process by excluding antagonistic engineering interactions (i.e., biomechanical warfare) between two ecosystem engineers: the bioturbating lugworm Arenicola marina and the sediment-stabilizing seagrass Zostera noltii Hornem. Applying a shell layer underneath half of our seagrass transplants successfully reduced adult lugworm density by over 80% and reduced lugworm-induced microtopography (a proxy for lugworm disturbance) at the wave-sheltered site. At the wave-exposed site adult lugworm densities and microtopography were already lower than at the sheltered site but were further reduced in the shell-treated units. Excluding lugworms and their bioengineering effects corresponded well with a strongly enhanced seagrass growth at the wave-sheltered site, which was absent at the exposed site. Enhanced seagrass growth in the present study was fully assigned to the removal of lugworms' negative engineering effects and not to any (indirect) evolving effects such as an altered biogeochemistry or sediment-stabilizing effects by the shell layer. The context-dependency implies that seagrass establishment at the exposed site is not constrained by negative ecosystem-engineering interactions only, but also by overriding physical stresses causing poor growth conditions. Present findings underline that, in addition to recent emphasis on considering positive (facilitating) interactions in ecological theory and practice, it is equally important to consider negative engineering interactions between ecosystem-engineering species. Removal of such negative interactions between ecosystem-engineering species can give a head start to the target species at the initial establishment phase, when positive engineering feedbacks by the target species on itself are still lacking. Though our study was carried out in a marine environment with variable levels of wave disturbance, similar principles may be expected to apply to other ecosystems that are inhabited by ecosystem engineers.