Waterbird-mediated passive dispersal is a viable process for crayfish (Procambarus clarkii)

Human transport and active dispersal of the red swamp crayfish (Procambarus clarkii) contribute to its rapid spread. However, some small aquatic organisms can be transported by birds. We made two hypotheses related to waterbird-mediated passive dispersal of juvenile crayfish. The first is that, depending on water depth, recently hatched crayfish can attach to ducks, initiating passive external transport (i.e., ectozoochory). The second is that recently hatched crayfish can survive bird flight, being affected by crayfish features, flight distance, and environmental conditions. A first experiment tested the attachment of juvenile crayfish to ducks at different water depths by using a freshly dead duck and tanks with crayfish. Another set of three experiments tested crayfish survival during air transportation. To simulate bird flight, we first used a vehicle moving at bird flight speed, and we then used trained pigeons. Several flight distances, environmental conditions, and crayfish sizes were tested. Our results showed that juvenile crayfish were capable of clinging to duck feathers and were transported when ducks were removed from the water. Furthermore, some juveniles of P. clarkii were able to survive long-distance transport when suspended outside a moving vehicle or when transported by birds. The probability of success was affected by water depth, crayfish size, distance travelled, and relative humidity. Our results support the occurrence of passive transportation of this invader by means of attachment to birds. These findings indicate that waterbird-mediated passive dispersal should be taken into account to explain P. clarkii’s rapid spread and should be considered when managing its invasions.     

In situ shifts of predominance between autotrophic and heterotrophic feeding in the reef-building coral Mussismilia hispida: an approach using fatty acid trophic markers

Coral Reefs - Many species of reef-building corals are mixotrophic, relying on both photoautotrophy performed by their dinoflagellate symbionts and heterotrophy from consumption of zooplankton....     

Waterbird-mediated passive dispersal of river shrimp <Emphasis Type="Italic">Athyaephyra desmaresti</Emphasis>

The river shrimp Athyaephyra desmaresti is a Mediterranean species which in recent years expanded its distribution, colonizing rivers of central Europe. The purpose of this study was to investigate the possibility of passive external dispersal of the river shrimp Athyaephyra desmaresti by waterfowl. We performed experiments testing shrimp desiccation survival, probability of attachment to waterfowl, and probability of successful transport. We found that in the laboratory 10% of the river shrimps can survive out of water for up to 90.1 min, but this period was reduced to 18.5 min under simulated bird flight conditions. Two different outdoor experiments simulating bird flight conditions indicated a 50% probability of successful transport on flight distances over 15 km. Our results using dead ducks show evidence that small, large or ovigerous river shrimps can attach to and be transported by ducks and that this capacity is affected by water depth. This study demonstrated that waterbird-mediated passive dispersal of river shrimps can occur and may be important for genetic flows between populations and for the colonization of new sites.     

Ectozoochory as a possible vector enhancing the spread of an alien amphipod Crangonyx pseudogracilis

Most studies of biological invasions refer to the human role in species dispersal but the importance of ectozoochory has scarcely been studied. Thus, we investigated whether the first alien amphipod species found in the Iberian Peninsula, North American Crangonyx pseudogracilis can be dispersed by waterfowl. To do this, we showed experimentally that the amphipod may cling to the plumage and legs of a mallard duck (Anas platyrhynchos) and be transported under controlled laboratory conditions. The probability of the amphipods being transported on duck’s plumage or feet is 1.84 and 1.6%, respectively. Another experiment showed that C. pseudogracilis may stay attached to a flying duck and survive during its flight for a distance of 6.8 km. In addition, we found that this invader can stay alive with a LT₉₀ of 88.6 min when exposed to desiccation. Thus, we conclude that C. pseudogracilis may be successfully transported by the waterfowl for short distances to other waterbodies. Thus, ectozoochory may be an important way of spreading the amphipods in areas where the hydrological network is poorly developed and not interconnected with artificial canals.     

Environmental cues during overland dispersal by three freshwater invaders: Eriocheir sinensis,Pacifastacus leniusculus,and Procambarus clarkii (Crustacea,Decapoda)

Freshwater crustaceans are known to disperse overland, aiding the invasion of new environments. To analyze the effect of environmental variables (humidity, temperature, illuminance, vegetation, and slope) on the movement direction of Eriocheir sinensis (H. Milne Edwards, 1853), Pacifastacus leniusculus (Dana, 1852) and Procambarus clarkii (Girard, 1852) in land, the animals were placed at the centre of a metal gutter and given a choice between two values of each variable. Chi-squared tests revealed significant preferences for E. sinensis to move downhill, P. leniusculus to move toward cooler areas and P. clarkii to move downhill and toward cooler areas. To test the ability of P. leniusculus and P. clarkii (E. sinensis was not present at the testing site) to return to water, they were placed in a circular arena near the river bank and their direction of movement was recorded. Chi-squared tests revealed that P. leniusculus, when isolated and in groups of 6, showed a significant tendency to move downstream, but not directly toward the water. P. clarkii showed no significant preference in movement direction. Since movement direction and overland dispersal are influenced by environmental gradients of temperature and elevation, these variables are fundamental for predicting autonomous overland dispersal and colonization patterns.     

Diagnostic and prognostic biomarker discovery strategies for autoimmune disorders

Current clinical, laboratory or radiological parameters cannot accurately diagnose or predict disease outcomes in a range of autoimmune disorders. Biomarkers which can diagnose at an earlier time point, predict outcome or help guide therapeutic strategies in autoimmune diseases could improve clinical management of this broad group of debilitating disorders. Additionally, there is a growing need for a deeper understanding of multi-factorial autoimmune disorders.Proteomic platforms offering a multiplex approach are more likely to reflect the complexity of autoimmune disease processes. Findings from proteomic based studies of three distinct autoimmune diseases are presented and strategies compared. It is the authors' view that such approaches are likely to be fruitful in the movement of autoimmune disease treatment away from reactive decisions and towards a preventative stand point.     

Factors determining active dispersal capacity of adult Chinese mitten crab <Emphasis Type="Italic">Eriocheir sinensis</Emphasis> (Decapoda,Varunidae)

The Chinese mitten crab (Eriocheir sinensis) is an invasive crustacean with a widespread distribution, sometimes overlapping with the red swamp crayfish (Procambarus clarkii). E. sinensis performs long river migrations, often moving overland to cross obstacles, but the factors affecting its movement are not well known. We studied its movement speed in and out of water, the survival time out of water and also its interaction with the red swamp crayfish during dispersal. At 16°C the LT₅₀ (time to death of 50% of the individuals) was 70 h, with a mean weight loss of 20%, and at 24°C the LT₅₀ was 31 h, with a mean 22% weight loss. In and out of the water, these crabs moved with mean velocities of 0.074 and 0.016 m s^?1, respectively. P. clarkii did not affect the dispersion of E. sinensis. This crab was able to disperse under various environmental conditions and its speed was affected by density, temperature, relative humidity, carapace length, and condition of the individuals (Fulton index). Moreover, we found that this species has a great capacity to resist desiccation. These characteristics give them all the requirements to successfully invade and adapt to new areas.     

Environment and host-related factors modulate gut and carapace bacterial diversity of the invasive red swamp crayfish (Procambarus clarkii)

Hydrobiologia - The invasive red swamp crayfish Procambarus clarkii is present in most of the Portuguese rivers with well-known economic and environmental impacts, being also an important reservoir...