Copepods are the most abundant zooplankton group in the ocean and play a pivotal role as grazers of microorganisms and prey for larger animals. Furthermore, they are major contributors to the pool of dissolved organic material in the pelagic and therefore play an important role in the microbial loop. Although biology of copepods has been under investigation for more than a century, few studies have looked at the relationship between copepods and their associated bacteria. Could copepods be perceived as distinctive microbial hotspots in nutrient poor pelagic environment? The microbiota of three Pleuromamma species, an abundant genus of copepods that migrate vertically from surface waters to several hundred meters water depth and back on a daily basis was investigated using various molecular and morphological techniques. The focus was on the differences in the bacterial community composition of these copepods along the Atlantic Meridional Transect, which traverses major oceanic biomes such as the subtropical gyres and the equatorial convergence region. Additionally, the community structure and stable isotope composition of the likely microplankton food source as well as the Pleuromamma copepods was assessed along the same cruise transect. Sequencing of 16S rRNA tag libraries derived from individual Pleruromamma copepods showed a broad diversity of Bacteria associated with these copepods. These bacterial communities were uniform across the oceanic provinces and Pleuromamma species. These results were reflected in the uniformity of the prey community composition, however there was an indication that Pleuromamma copepods from different regions in the Atlantic rely on different food sources. Fluorescence in situ hybridisation and electron microscopy showed the presence of bacteria in the midgut region of the copepod guts and more specifically a high abundance of Betaproteobacteria. The bacterial community of a dominant copepod species in the Atlantic has previously not been studied on such a large spatial scale and sample size. This study shows that the same bacterial taxa were associated with Pleuromamma copepods inhabiting distinct oceanic regions. Moreover, a betaproteobacterial genus not present in the water-column appears to be closely associated with Pleuromamma.

The expanded use of platinum group elements (PGEs), platinum (Pt), palladium (Pd), and rhodium (Rh), in automobile catalysts has led to increased levels of these metals in aquatic environments. However, data regarding acute toxicity and the sublethal effects of these metals on aquatic biota are limited. This study aimed to explore the response of the freshwater amphipod Gammarus pulex to PGEs. Investigations included the 96 LC50 test and several behavioural (vertical movement and feeding activity) and biochemical (acetylcholinesterase (AChE); osmoregulation; 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) reduction; reduced glutathione (GSH); glutathione-S-transferase (GST); thiobarbituric acid reactive substances (TBARS); heat shock proteins (HSPs) and protein phosphorylation) endpoints. Pd caused a significant reduction in the survival of G. pulex with a 96 h LC50 of 0.52 mg/L (4.89 μM). Pt or Rh increased the survival of G. pulex exposed to Pd. However, this was not associated with reduced Pd uptake. Exposure for 24 h to 0.5 mg/L Pd (4.69 μM) significantly decreased the vertical movement (64%) and feeding activity (95%) of G. pulex. However, lower Pd concentrations (≥0.25 mg/L (2.3 μM)) took 72 h to induce significant inhibition in feeding activity (50%). AChE activity was significantly increased (40%) following 72 h exposure to 0.5 mg/L Pd. GST activity was significantly inhibited (≥32%) following 72 h exposure to ≤0.25 mg/L Pd. The concentration of GSH was significantly increased (22 and 35%) following 72 h exposure 0.1 (0.94 μM) and 0.5 mg/L Pd2+, respectively. Exposure to ≤0.1 mg/L Pd caused a significant decrease (≤27%) in MTT reduction and significant increase (≤70%) in HSP60 content in mitochondrial extract (pellet) after 72 and 24 h exposure, respectively. The reactivity of anti-phosphoserine bodies with protein bands corresponding to 245 kDa in the pellet was significantly increased (38%) by exposure of gammarids to 0.5 mg/L Pd. Exposure to 0.1 mg/L Pd significantly increased (32%) the intensity of a 30 kDa anti-phosphothreonine reactive protein band in the post-mitochondrial extract, but higher Pd doses had no effect. In conclusion, this study provides original data suggesting the mitochondria as a main target of Pd toxicity. Further studies of Pd toxicity, under both laboratory and field conditions, are needed including the effect of long-term exposure to low Pd concentrations.

No description available.

No description available.

No description available.

Study of the biology and ontogeny of Cretaceous and Recent ostracods shows that the family Cyprididae exhibits conservative evolution over the last 100 million years. The Cretaceous cypridid ostracod Pattersoncypris micropapillosa Bate, 1972, with preserved appendages, is described and details of the limbs of its adults and juveniles are compared with Recent Cyprididae. A detailed study of the ontogeny of the Recent Cyprididae ostracod Eucypris virens Jurine, 1820) reveals that, with the exception of the last podomere on the antennules, the chaetotaxy (distribution pattern of setae) shows continual development on all podomeres of the limbs. Cyprididae ostracods have a pediform limb in the posterior part of the body, presumably to help them to attach to substrates; this is reflected by the pediform nature of one limb in all ontogenetic stages. This study has also shown that the fifth limb is more probably of thoracic origin and, hence, ostracods have only one pair of maxillae. The upper lip and hypostomes of 23 species of Cypridoidea (Podocopina) ostracods were studied and significant variation noted in morphology between species, genera and subfamilies. Several features of the upper lip and hypostome are described for the first time. The morphology of the upper lip can be used to identify species, but it cannot be used to diagnose genera or subfamilies. Spherical objects recovered from acetic acid preparation residues of vertebrate fossils from the Lower Cretaceous Santana Formation of north-east Brazil are postulated to be the eggs of the ostracod Pattersoncypris micropapillosa Bate, 1972. These spheres are phosphatized, range in diameter from 85 to 110 m, and are comparable in many respects to the eggs of several Recent ostracod species.

No description available.

No description available.

Barnacles are considered to be one of the major marine fouling organisms. Their settlement behaviour has been investigated using mainly Balanus amphitrite as a model organism. To better understand the mechanisms involved during the colonisation of surfaces by cypris larvae we have investigated another species, B. improvisus, which is reported to have different surface preferences compared to B. amphitrite. This study aims to unravel the effects of surface physicochemical cues, in particular surface free energy (SFE), surface charge and elastic modulus on the settlement of cyprids of both species. The use of well-defined surfaces under controlled conditions further facilitates comparison of the results with B. amphitrite. Furthermore, since this phase of presettlement behaviour is characterised by temporary adhesive (footprint) deposition, considered to be fundamental to surface exploration and surface discrimination by cyprids, some of the chemistries used for the settlement assays were used to investigate temporary adhesive-surface interactions. Cyprids were exposed to a series of model surfaces, namely self-assembled monolayers (SAMs) of alkanethiols with varying end-groups, homogenously applied to gold-coated polystyrene Petri dishes. The settlement response was significantly higher on negatively charged SAMs and lower on positively charged surfaces, while intermediate settlement occurred on neutral SAMs. Furthermore, no effects were observed when data were plotted against surface free energy after 48 hr of exposure. Temporary adhesive on SAMs was investigated using imaging ellipsometry and atomic force microscopy. Relatively thick footprints with low wetting were found on positively charged surfaces. Settlement of both species was also low on these surfaces. Footprints were thinner and spread more on hydrophobic surfaces. The adhesion force of temporary adhesive measured with functionalised AFM tips was higher on hydrophobic and negatively charged surfaces for both species. Furthermore, PDMS-based surfaces were prepared varying the elastic modulus, keeping constant other parameters, settlement behaviour and strength of adhesion of juveniles and adults were tested. We conclude that cyprid settlement behaviour of both species is influenced more by surface charge than SFE under controlled conditions. The temporary adhesives (footprints) of the two species had a stronger affinity for hydrophobic surfaces. Contrary ii to previous reports, therefore, the settlement preferences and adhesive secretion of these two species are similar. Elastic modulus influences settlement, juveniles and adults removal of both species, although B. improvisus is more sensitive if compared with B. amphitrite. This finding will be important for understanding the mechanism of surface selection by cyprids and for the development of future antifouling technologies.

Parasites can structure communities and may impact on resource competitive interactions in novel communities. The amphipod Gammarus pulex is invasive in Ireland and in low land river stretches has displaced the native congener Gammarus duebeni celticus. Parasitism may facilitate invasion success by the more efficient use of resources. The functional response (the relationship between prey density and prey consumption) is a means of predicting the likely impact of an invader. In this thesis parasitism by two different acanthocephalan parasite species (Echinorhynchus truttae and Polymorphus minutus) elevated the functional response of G. pulex with either Baetis rhodani or Asellus aquaticus prey. Analysis of prey body part consumption in Baetis rhodani prey by E. truttae parasitised G. pulex revealed that parasitised predators consumed more prey material, partially consumed more prey but consumption distribution was not related to body part. In turn, partial prey consumption may reduce handling time in parasitised predators and may provide a mechanistic explanation for the elevation of functional response parameters. Unconsumed prey provide an additional food source for consumers that are too small or slow to capture larger prey, with consequences for nutrient cycling within freshwater communities. With regards to physiological parameters, non-starved parasitised and unparasitised G. pulex had similar haemolymph protein levels whereas starvation significantly elevated the haemolymph protein level of parasitised G. pulex compared to unparasitised animals. This finding suggested parasite upregulation of host protein resources to compensate for depletion of host haemolymph protein levels during starvation. Additionally, long term starvation did not affect survival rate in parasitised or unparasitised G. pulex but appeared to impact on parasite length in parasitised hosts.. Parasitised invasive predators such as G. pulex may therefore possess traits that allow more efficient use of resources compared to native congeners, which may facilitate and explain the invasion success of this species.