Showing papers in "Marine and Freshwater Behaviour and Physiology in 2006"

Crayfish invading Europe: the case study of Procambarus clarkii

Abstract: The red swamp crayfish, Procambarus clarkii, native to northeastern Mexico and southcentral USA, is today the dominant macroinvertebrate in several European countries. While the first introduction of this species into Spain is well-documented, little is known about its pathways of invasion and the reason for its rapid spread in several European countries. Study of the biology of the species has revealed a number of properties that makes this crayfish a successful invader. Procambarus clarkii exhibits properties characteristic of an r-selected species, including early maturity at small body size, rapid growth rates, large numbers of offspring at a given parental size, and relatively short life spans. It is also plastic in its life cycle, able to disperse widely in the habitat and to tolerate environmental extremes. It displays generalist and opportunistic feeding habits, consuming macrophytes and preying on amphibians. Procambarus clarkii can also replace indigenous crayfish by a combination of mechanisms,...

Orientation and navigation in Amphibia

Abstract: Aquatic and terrestrial amphibians integrate acoustic, magnetic, mechanical, olfactory and visual directional information into a redundant–multisensory orientation system. The sensory information is processed to accomplish homing following active or passive displacement by either path integration, beaconing, pilotage, compass orientation or true navigation. There is evidence for two independent compass systems, a time-compensated compass based on celestial cues and a light-dependent magnetic inclination compass. Beaconing along acoustic or olfactory gradients emanating from the home site, as well as pilotage along fixed visual landmarks also form an important part in the behaviour of many species. True navigation has been shown in only one species, the aquatic salamander Notophthalmus viridescens. Evidence on the nature of the navigational map obtained so far is compatible with the magnetic map hypothesis.

Short-range orientation in fish: How fish map space

Abstract: One way in which fish can move around efficiently is to learn and remember a spatial map of their environment. This can be a relatively simple process where, for example, sequences of landmarks are learned. However, more complex spatial representations can be generated by integrating multiple pieces of information. In this review, we consider what types of information fish use to generate a spatial map; for instance, beacons (single landmarks) that signal a specific location, or learned geometric relationships between multiple landmarks that allow fish to guide their movements. Owing to the diversity of fish species and the broad range of environments that they inhabit, there is considerable diversity in the maps that they develop and the sensory systems that they use to detect spatial information. This chapter uses a series of examples to investigate the types of spatial information that fish encode, for instance, how they map three-dimensional space, how they make use of different sensory modalities, an...

Osmoregulation in elasmobranchs: a review for fish biologists, behaviourists and ecologists

Abstract: This article provides a broad review of osmoregulation in elasmobranchs for non-specialists, focusing on recent advances. Marine and euryhaline elasmobranchs in seawater regulate urea and other body fluid solutes (trimethylamine oxide (TMAO), Na+, Cl−) such that they remain hyper-osmotic to their environment. Salt secretions of the rectal gland and excretions in the urine compensate for continuous inward diffusion of environmental salts. Freshwater and euryhaline elasmobranchs in fresh water synthesise less urea and retain less urea and other body fluid solutes compared to marine elasmobranchs and thus have relatively lower osmolarity. Electrolyte uptake at the gills and kidney reabsorption of salts maintain acid–base balance and ionic consistency. The role of the gills, kidney, liver and rectal gland in elasmobranch osmoregulation is reviewed. The ontogeny of osmoregulatory systems in elasmobranchs and the contribution of drinking and eating processes in maintaining osmotic consistency are discussed. Rec...

Keynote papers on sandhopper orientation and navigation

Abstract: This article analyses the relevant studies that have made sandhoppers a model subject for the study of orientation, and traces the development of the paradigm through innovative hypotheses and empirical evidence. Sandhoppers are able to maintain their direction without sensorial contact with the goal, which is their burrowing zone extended along the beach, but very narrow across it. They actively determine the direction of their movements, according to their internal state and the environmental features encountered. Each population shows an ‘innate directional tendency’ adapted to the shoreline of origin, and the inexpert laboratory-born young behave in a similar way to the adults. Genetic differences have been demonstrated between, as well as within natural populations. The question of the calibration of the sun compass to orientation on a particular shoreline implies a redundancy of mechanisms of orientation. Orientation mechanisms may involve environmental cues perceived through diverse sensory modalit...

Orientation and navigation in coastal and estuarine zooplankton

Abstract: The axiom that zooplankton species exhibit upwards migration behaviour at night is challenged by recent findings. Such behaviour is not universal, may vary during ontogeny, and is occasionally reversed. Moreover, in some estuarine and coastal zooplankton species vertical migration rhythms are of tidal, not diel, periodicity. There is evidence for several species that vertical migrations are endogenously controlled, occurring in constant conditions in the laboratory, suggesting that they have arisen under considerable selection pressure. They appear to play a significant role in orientation and navigation of coastal and estuarine zooplankton, predicated on the selective advantage of closure of life cycles. Vertical migrations between water masses moving in different directions at tidal, diel or longer timescales permit dispersal and recruitment, or retention, of planktonic larvae and adults in favourable ecological locations. Exogenous factors serving as cues for, or directly controlling, vertical migratio...

Sea turtles, lobsters, and oceanic magnetic maps

Abstract: Numerous marine animals can sense the Earth's magnetic field and use it as a cue in orientation and navigation. Two distinct types of information can potentially be extracted from the Earth's field. Directional or compass information enables animals to maintain a consistent heading in a particular direction such as north or south. In contrast, positional or map information can be used by animals to assess geographic location and, in some cases, to navigate to specific target areas. Marine animals exploit magnetic positional information in at least two different ways. For hatchling loggerhead sea turtles, regional magnetic fields function as open-sea navigational markers, eliciting changes in swimming direction at crucial points in the migratory route. Older sea turtles, as well as spiny lobsters, use magnetic information in a more complex way, exploiting it as a component of a classical navigational map, which permits an assessment of position relative to specific geographic destinations. These “magnetic ...

The stomatopod rumble: Low frequency sound production in Hemisquilla californiensis

Abstract: Stomatopods (mantis shrimp), numbering over 450 species, are renowned for their exceptional visual and chemosensory abilities and yet virtually nothing is known about their use of acoustic signals. We present acoustic recordings and analyses of the sounds of a stomatopod, Hemisquilla californiensis. This species generates tonal, low frequency sounds, which we term ‘rumble’, that are spectrally similar to those produced by African and Asian elephants. The fundamental frequency of the stomatopod rumble ranges from 20 to 60 Hz, with a strong second harmonic. Hemisquilla californiensis appears to generate these sounds through contractions of the posterior mandibular remotor muscle which is coupled to a stiff, lateral extension of the carapace. The sides of the carapace are covered by large, polarized, red spots which vibrate during sound production. Thus, the animals may generate a multi-modal signal by coupling vibrational and visual signals. Hemisquilla californiensis generates the rumble while interacting ...

The migratory behaviour of North Sea plaice: Currents, clocks and clues

Abstract: Water currents are a dominant feature of the open sea and often play an important part in the life cycle of the fish that live there. For over three decades, a focus of research at Lowestoft has been the role of tidal water currents as a part of wider understanding of the population dynamics of plaice (Pleuronectes platessa) in the North Sea. Increasingly sophisticated telemetry methods have been developed and used, initially to describe the migratory behaviour of individual fish, and latterly to describe the spatial dynamics of whole populations. Here, the authors review cues and clues for environmental transport at different life stages, with a critical evaluation of the facultative use of selective tidal stream transport in relation to water current speed. The clues that trigger movement into mid-water by adult fish are reconsidered in light of new findings. Finally, the orientation capabilities of plaice, together with evidence of repeat migrations and spawning site fidelity were examined.

An inducible release of reactive oxygen radicals in four species of gorgonian corals

Abstract: The capability for physical injury or heat stress to elicit the production of reactive oxygen species was examined in four species of gorgonian corals. The sea plumes Pseudopterogorgia elisabethae, Pseudopterogorgia americana, the sea rod Eunicea fusca and the azooxanthellate red branching gorgonian Lophogorgia chilensis were physically injured using sonic sound cavitations and heat shocked by incubation in 33°C sea water. The pharmacological probe, diphenylene iodonium chloride (DPI), an inhibitor of NAD(P)H oxidase and peroxidases was used to identify an enzymatic surrogate of the oxidative burst. Both injury and heat stress were capable of inducing the release of reactive oxygen species (ROS) in all gorgonians tested, yet the kinetics and amplitude of ROS release varied among genera. In both the treatments, P. americana demonstrated the largest oxidative burst among the other corals tested.

Navigation of marine, freshwater and coastal animals: concepts and current problems

Abstract: The animals from the environments focused on here share the same navigational mechanisms with terrestrial animals. However, some of them seem to rely on additional ways of detecting and/or processing navigational cues, some of which are perhaps still unknown. A classification of the mechanisms of navigation is given. This is based on the source of information that animals use to head for their targets. A selected series of phenomena of current interest is presented, starting with olfactory beaconing in oceanic birds, which allows the detection of patchily distributed food and productive areas from long distances. Animals of sandy beaches rely on an array of mechanisms of orientation, which have an adaptive value for their ecotonal system. As some species are capable of using both the moon and sun compass in orientation, attention and experiments are focused on the significance of these celestial cues in the navigational process. Two clocks of different periods, one of which would appear to regulate both t...

The impacts of flow on chemical communication strategies and fight dynamics of crayfish

Abstract: Signal transmission is influenced by the physics of an environment. Consequently, a physical effect on sensory signals can influence how animals send or sample sensory information. Habitat-specific physics may constrain or enhance signal transmission (e.g. sound transmission in a flowing river versus a still pond) and provide a mechanism for the evolution of sensory biases. This study investigated how the transmission of chemically mediated social signals in crayfish is influenced by two different aquatic environments. Agonistic bouts between crayfish were performed under lotic (flowing water) and lentic (nonflowing, still water) conditions. When crayfish (Orconectes rusticus) collected from a lotic system (river) interacted under lotic conditions, we noted that dominant O. rusticus spent more time upstream than subordinate O. rusticus. Orconectes rusticus positioned themselves randomly and spent equal amounts of time with respect to upstream and downstream in the nonflowing environment. We tested another...

Review: Depth, navigation and orientation in crabs: Angular acceleration, gravity and hydrostatic pressure sensing during path integration

Abstract: This review shows how well the published work on the neural basis of balance and hydrostatic pressure reception in crabs agrees with the analyses and models of path integration. Fiddler crabs allow analyses at the level of behaviour. With considerable accuracy, they continuously show the direction to home with their body orientation and use idiothetic path integration to calculate a home vector from the internal measurements of their locomotion. All crabs have a well-developed vestibular system in the statocyst with horizontal and vertical canals which is used for angular acceleration sensing and depth reception. Large identified interneurones abstract the component of angular acceleration in one of the three orthogonal planes. These have properties consistent with a key role in path integration, combining vestibular and proprioceptor information with a central excitatory drive from the hemiellipsoid bodies. They have been monitored during walking, swimming and even in freefall for a 22 s period in parabo...

Effect of invasive tagging on the activity of Holothuria whitmaei [Echinodermata: Holothuroidea]: A suitable mark-recapture method for short-term field studies of holothurian behaviour

Abstract: Although mark-recapture techniques traditionally have been used to obtain ecological data, tagging of soft-bodied holothurians has proven difficult, and the degree to which invasive tags may confound the behaviour of holothurians remains unclear. In this study, diurnal patterns of activity were monitored in the commercial sea cucumber Holothuria whitmaei (black teatfish) after marking the tegument superficially with a number measuring 30 × 20 mm (to a depth of ≤2 mm). Rates of activity in marked specimens increased significantly in the initial hours following marking, and remained higher than those of unmarked control animals for up to 3 days following the procedure. These results suggest (a) that behaviour in holothurians may initially be compromised by marking the tegument and (b) that improved measures of activity may be obtained following a suitable recovery period. This is a useful finding given the need for improved knowledge of commercial holothurian biology, including diurnal and seasonal patterns...

Metamorphosis of a sesarmid river crab, Armases roberti : stimulation by adult odours versus inhibition by salinity stress

Abstract: In an experimental laboratory study with the megalopa stage of Armases roberti, a freshwater-inhabiting species of crab from the Caribbean region, we evaluated the combined, potentially antagonistic effects of odours from conspecific adults and of stepwise salinity reductions (simulating upstream migration, reaching within 1 week conditions of 2‰ or freshwater). Neither of these treatments affected the rate of survival, but the duration of development to metamorphosis was significantly (by about 25%) shortened, when odours from conspecific adult crabs were present, regardless of the salinity conditions. Our results indicate that the metamorphosis-stimulating effect of chemical cues from an adult population of A. roberti is far stronger than the potentially retarding effect of increasing hypoosmotic stress. This suggests that the final phase of larval development, including the processes of settlement and metamorphosis, occurs in this species in freshwater habitats, where conspecific populations live.

Reproductive seasonality and maturity of male Neophocaena phocaenoides asiaeorientalis in captivity: A case study based on the hormone evidence

Abstract: To provide hormone evidence on reproductive seasonality and maturity of the Yangtze finless porpoise, the authors monitored the monthly variations of serum reproductive hormones of a male Yangtze finless porpoise in captivity via radioimmunoassay from 1997 to 2003. It was demonstrated that the immature animal had a serum T level of 28-101ngdL -1 (6552ngdL -1 ), reached puberty with the serum T concentration ranging between 250 and 590ngdL -1 (390130ngdL -1 ), and attained reproductive maturity when the serum T level went beyond 1120180ngdL -1 in the breeding season. The body length growth of the animal showed a pattern similar to the serum T variations during its adolescent period from the age of 4 to 6 years. Moreover, the serum T concentration of the male porpoise exhibited significant seasonal variations, indicating that its breeding season may start as early as March and end as late as September.

The use of computer-assisted motion analysis for quantitative studies of the behaviour of barnacle ( Balanus amphitrite ) larvae

Abstract: The effects of larval density and age on pre-settlement swimming behaviour of Balanus amphitrite cyprid larvae were studied with the aid of computer-assisted motion analysis. Swimming behaviour was monitored in individual, in groups of 10–15 and in groups of 50–100 cyprids. There was a small, but significant effect of larval density on swimming speed and no effect on two other quantitative measures: rate of change of direction and net-to-gross displacement ratio. There was also small but significant variation in swimming speed between different batches of cyprids over the course of 2 years. Swimming behaviour of individual cyprid larvae was also monitored daily for 7 days, with the larvae maintained in the cold and dark between measurements to prevent settlement and metamorphosis. There were no significant behavioural differences observed over time indicating that larvae may be held in this manner experimentally without affecting these parameters.

Visual field of cultured striped trumpeter Latris lineata (Teleostei) larvae feeding on rotifer prey

Abstract: The visual field of striped trumpeter Latris lineata larvae fed rotifer prey was determined from analysis of feeding behaviour in the horizontal plane. The visual field was forward and laterally directed, characterised by maximum reactive distances (distance at which the predator first detects and reacts to the prey) of 5.07 mm and 5.25 mm on days 13 and 17 post-hatching, respectively, 97% of mean larval length. This confirmed the predicted horizontal visual field, forward and laterally directed, derived from higher cone cell densities in the dorso-temporal and medial regions of the retina compared with ventral regions. The visual field of prey detection expanded laterally with ontogeny as a wider range of reactive angles was used by 17 day-old than 13 day-old larvae. Larvae displayed a saltatory searching pattern, periodically stopping to scan for prey throughout the visual field, and exhibited a side-to-side movement of the head as they approached and stopped, prior to striking at a detected prey item. Larvae on day 17 post-hatching terminated 35% of feeding sequences at the pre-strike position, at a mean distance from prey of 0.58 mm.

Correlation of chlorophyll a and total carotenoid concentrations with coral bleaching from locations on the Pacific coast of Mexico

Abstract: Diving campaigns were undertaken to study the bleaching phenomenon in the Mexican Central Pacific and to catalogue the degree to which bleaching affected three coralline reefs (la Boquita, Carrizales, and Tenacatita) Bleaching evaluations of Pocillopora capitata were conducted by assessing the concentrations of chlorophyll a and total carotenoids from samples along submarine transect lines We identified that the Reffs Boquita and Tenacatita locations were predominantly composed of bleached and pale coral populations The concentrations of chlorophyll a within the areas of the different populations were greater at sites of greater depth compared with those at the surface In contrast, the total carotenoid concentrations in normal pigmented coral at greater depth were significantly higher (P < 005) compared with both levels of discolouration at both depths The chlorophyll a/total carotenoid ratios in these populations are discussed as a potential mechanism responsible for the poor condition of these cor

Cardiovascular and respiratory responses associated with limb autotomy in the blue crab, Callinectes sapidus

Abstract: Cardiovascular and respiratory variables were recorded in the blue crab, Callinectes sapidus, during injury and subsequent autotomy of a chela. Cardiac function and haemolymph flow rates were measured using a pulsed-Doppler flowmeter. Oxygen uptake was recorded using an intermittent flow respirometry system. Crabs reacted to the loss of a chela with a rapid increase in heart rate, which was sustained for 2 h. Stroke volume of the heart also increased after the chela was autotomized. A combined increase in heart rate and stroke volume led to an increase in cardiac output, which was maintained for an hour after the loss of a chela. There was also differential haemolymph perfusion of various structures. There was no change in perfusion of the anterolateral arteries or posterior and anterior aortae, during injury of the chela or subsequent autotomy. Haemolymph flow rates did increase significantly through the sternal artery during injury and immediately following autotomy of the chela. This was at the expense...

The behaviour of a hawksbill turtle data-logged during the passage of hurricane Georges through the Caribbean

Abstract: Recent severe hurricanes in the Caribbean and south-east United States have had devastating socio-economic effects, and there is a pressing need to learn how animals are impacted by such events. We serendipitously deployed a multi-channel data logger onto a hawksbill turtle (Eretmochelys imbricata) during the breeding season in 1998 and logged various aspects of her behaviour before, during and after passage of hurricane Georges. As Georges passed by, the turtle made shorter dives, became more active and spent less time at the surface between dives compared with its baseline, non-storm activity. However, after passage of the hurricane the turtle quickly resumed its pre-hurricane behaviour and nested successfully a few days later. These results show that, in this case, the hurricane had a minor impact on the submerged animal presumably because of the dampening effect of depth on high winds over water.

Mechanosensory based orienting behaviors in fluvial and lacustrine populations of mottled sculpin ( Cottus bairdi )

Abstract: We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities, Coweeta Creek sculpin show varying levels of positive rheotaxis at low to intermediate velocities and often reduced positive rheotaxis or even negative rheotaxis at the highest velocities (12 cm s−1). Blinded Lake Michigan, but not Coweeta Creek mottled sculpin exhibited an orienting response to a small (3 mm diameter) artificial prey (50 Hz vibrating sphere). In conclusion, the two populations differed in the strength and polarity of the rheotactic response at higher velocities and in their responsiveness to mechanosensory cues from epibenthic prey sources. These behavioral differences have most likely arisen from different learning exper...

The mate pursuit-predation avoidance tradeoff in the virile crayfish, Orconectes virilis

Abstract: To better understand the tradeoff between mate pursuit and predation risk avoidance, the responses of male virile crayfish (Orconectes virilis) to female sex pheromone and conspecific alarm cue, alone and in combination were tested. Male crayfish were more active and exhibited less antipredator behavior in the pheromone treatment than in either the pheromone + alarm or alarm treatment. The results suggest a tradeoff in favor of risk avoidance when pheromone and risk stimuli are encountered together.

Interindividual variation of malate dehydrogenase activity in the oyster Crassostrea virginica

Abstract: Intertidal environments are dynamic, stressful niches and variation in physiological parameters may determine distribution and survival of individuals in a population. We demonstrated that mitochondria of the oyster Crassostrea virginica oxidize malate more readily than other Krebs cycle intermediates and investigated the level of interindividual variability in oyster malate dehydrogenase (MDH) activity and total protein content in muscle tissues. Both MDH activity and total protein evidenced a high level of interindividual variation in heart and adductor among a sample of more than 50 oysters. Normalization to total DNA failed to explain the variation in either MDH activity or protein content of phasic adductor and explained less than 40% of the variation in heart. This range of MDH titers defines a continuum of biochemical phenotypes important for understanding the relative selection forces operative on metabolic pathways within the muscles of the oyster.

Correlation between the morpho-cytohistochemistry of the outer mantle epithelium of Anodonta cygnea with seasonal variations and following pollutant exposure

Abstract: Seasonal and experimental conditions induce morphological and cytochemical variations in the outer mantle epithelium (OME) of the freshwater bivalve Anodonta cygnea, probably influencing the shell calcification mechanism. In this study, OME samples were taken from untreated animals in autumn, winter, spring and summer as well as from animals exposed to divalent metals (cadmium, chromium, lead, copper and zinc) and pesticides (setoxidim and dimethoate) and observed by light microscopy. The present results showed that OME cells have larger cell volumes and increased amounts of secreted macromolecules during spring and summer than in autumn and winter. This correlates with higher shell calcification rates in spring and summer and lower shell calcification rates in autumn and winter. The experiments showed that incubation with pollutants for 8 months dramatically reduced the cellular volume so that the density of cytoplasmic material appeared higher that in the control samples. The pronounced changes in OME c...