Search results for "Crustacea"
showing 10 items of 244 documents
A first snapshot of sandy-beach amphipod (Crustacea) assemblage in a Marine Protected Area, Favignana Island (central Mediterranean Sea)
2017
The aim of this study is to compile a preliminary first check-list of Amphipoda species from beaches of Favignana Island (Sicily, Italy), and contribute to the knowledge relating to the distribution of this taxon in the Mediterranean Sea. Five amphipod species, belonging to two families (Talitridae and Hyalidae), have been collect in the island. The supralittoral assemblage appears to contain three main biogeographical categories: Atlanto-Mediterranean species, Mediterranean endemic species and cosmopolitan species.
Food selection in Eucypris virens (Crustacea: Ostracoda) under experimental conditions
2007
Ostracods have long been studied by scientists because their fossil remnants provide a valuable tool for the reconstruction of past environmental changes, including climate change and anthropogenic eutrophication. Relatively little is known about the physiology, behaviour and reproductive ecology of recent forms. We argue that filling this gap in knowledge requires stable cultures that can be used in laboratory studies. Here we provide quantitative information on the food preference of the common non-marine ostracod Eucypris virens. Using an experimental device allowing a free choice of eight food items, including both auto- and heterotrophic organisms, observations were carried out on grou…
A respiratory hemocyanin from an insect.
2004
Insects possess an elaborate tracheal system that enables transport of gaseous oxygen from the atmosphere directly to the inner organs. Therefore, the presence of specialized oxygen-transport proteins in the circulatory system of insects has been considered generally unnecessary. Here, we show for the first time, to our knowledge, the presence of an ancestral and functional hemocyanin (Hc) in an insect. In the hemolymph of nymphs and adults of the stonefly Perla marginata , a hexameric Hc was identified, which consists of two distinct subunit types of 659 and 655 amino acids. P. marginata Hc displays cooperative oxygen binding with a moderately high oxygen affinity [(half-saturation pressu…
Feeding habits of the spotted flounder Citharus linguatula off the eastern coast of Spain
1994
The composition of the diet of Citharus linguatula (L.) off the coast of the Gulf of Valencia, Spain, was determined between October 1989 and October 1990. The percentage of empty stomachs remained constant throughout the year, except for the period August to September, when a maximum was recorded coinciding with the reproductive period. Crustaceans (Mysidacea and Decapoda) and teleosts constituted the main prey. The composition of the prey ingested varied with predator size; small specimens contained a greater number of mysids in their stomachs, while decapods and fishes were more abundant in the stomachs of larger specimens. Diets varied seasonally: mysids were more important during autum…
Diel vertical movements of zooplankton in lake La Cruz (Cuenca, Spain)
2000
The study of diel vertical movements of zooplankton in a small meromictic karstic lake (lake La Cruz), presenting highly stratified waters, was performed using two different methodologies: (i) samples were taken along the vertical profile and were compared at different hours in a diel cycle; (ii) some plankton traps were located at different depths, covering different periods of time, to catch organisms going upwards and downwards. The main subject of this study has been the vertical movements affecting rotifers since they were dominant in the zooplankton of this lake, but we have also included the results obtained for other zooplankton groups. The results indicate an almost general movemen…
Surface glycoproteins in copepods: potential signals for mate recognition
1994
The mechanism male copepods use to recognize mates is not well understood. Both chemical and mechanical cues have been implicated, but the relative importance of these is not known. This lack of knowledge is despite the belief that mate recognition has a critical role in maintaining reproductive isolation of many species and influences the direction of evolution. Glycoproteins are used as mating signals by a number of aquatic organisms including rotifers, ciliates, and algae. We have developed techniques for selectively probing surface glycoproteins in zooplankton using fluorescently labeled lectins. We examined surface glycoproteins on the urosomes of several species of marine and freshwat…
Is activated hemocyanin instead of phenoloxidase involved in immune response in woodlice?
2008
In the Common woodlouse Porcellio scaber (Crustacea: Isopoda: Oniscidea), experimental immune challenge did not induce the expression of pro-phenoloxidase that, in most other invertebrates studied thus far, can be activated into phenoloxidase via an activation cascade upon immune challenge. Instead, Porcellio hemocyanin proved to exhibit catecholoxidase activity upon activation. However, none of the activating factors known from other invertebrates other than SDS-treatment resulted in activation of hemocyanin into a functional phenoloxidase in vitro. The distinct characteristics of isopod hemocyanin are reflected by the quaternary structure of the hemocyanin dodecamers that differs from tha…
Aggregation ofArgulus coregoni(Crustacea: Branchiura) on rainbow trout (Oncorhynchus mykiss): a consequence of host susceptibility or exposure?
2005
By sampling individual rainbow trout,Oncorhynchus mykiss, at a fish farm we showed thatArgulus coregoniwere aggregated within their host population. The relative significance of susceptibility and exposure generating the observed pattern was tested using experimental infections. We examined, whether rainbow trout developed protective resistance mechanisms against the louse following a challenge infection and if there was variation between individual trout in their susceptibility toA. coregonimetanauplii. Fish were exposed to 20A. coregonifor 5, 25, 50, 85 or 120 min and the numbers attaching recorded. Three weeks later, developing argulids were removed and the experiment repeated with a sta…
Seasonal dynamics of egg laying and egg-laying strategy of the ectoparasite Argulus coregoni (Crustacea: Branchiura).
2004
Substrate preferences, spatial aggregation patterns and seasonal dynamics in the egg laying of ectoparasiticArgulus coregoniwere studied at a commercial fish farm in Finland. Pilot experiments showed thatA. coregonifemales selected specific types of substrates for egg laying. Significantly moreA. coregonieggs were laid on dark substrates than on light ones suggesting the use of visual cues. Therefore, egg-laying plates of dark colour were constructed for further experiments. MostA. coregonieggs were deposited in locations in shadow and in the deepest water in a 2 m deep farming canal. Relatively more eggs were laid on bottom stones situated near each egg-laying trap than on artificial egg-l…
The food and parasites of fish in some deep basins of northern L. Päijänne
1982
The composition of the fish stock, food and ‘macroparasites’ were studied in eleven basins (22–100 m) of Lake Jyvasjarvi and North Paijanne in August–September 1976. The fishing was done by means of a series of nets (meshes 15, 21 and 35 mm) laid on the bottom overnight. No fish were found in the two northernmost basins owing to bad oxygen conditions caused by waste waters. Smelt and burbot were the most abundant fish in the catches in other basins but the vendace was rare. Relict crustaceans and some ‘deep water’ copepods (e.g. Heterocope borealis) played an important role in the food of fish in all basins.