Additions to Mexican freshwater copepods with the description of the female Leptodiaptomus mexicanus (Marsh)

A survey on 10 temporary and permanent water-bodies, located at more than 2000 m above the sea level in the central part of Mexico resulted in the presence of 17 cyclopoid and five calanoid copepods. From the total taxa found, seven are new to the country: Leptodiaptomus assiniboiaensis (Anderson), Microcyclops dubitabilis Kiefer, Ectocyclops rubescens Brady, Eucyplops cf. bondi Kiefer, Eucyclops cf. prionophorus Kiefer, Eucyclops pseudoensifer Dussart, and Eucyclops cf. solitarius. The female of Leptodiaptomus mexicanus, a species known only from a single male found near Mexico City in 1929, is here described for the first time. Copepod fauna for each of the systems was highly diverse, with up to 12 species co-occurring in temporary ponds. This study revealed a mixture of north and south American taxa in the area.     

Haplostoma dudleyae sp. nov. (Cyclopoida: Ascidicolidae), parasitic in Eudistoma olivaceum from the Indian River in southern Florida

Haplostoma dudleyae sp. nov. is described and illustrated on the basis of females found in a compound ascidian (Eudistoma olivaceum) collected from the Indian River in southern Florida, USA. Each parasitized zooid has a single female copepod. The egg sacs of the female are paired and, when laid, are almost U-shaped and folded against the dorsal side of the body. Haplostoma dudleyae and two other species (H. canui Chatton and Harant, 1924, and H. humesi Ooishi, 1995) constitute a subgroup within the genus Haplostoma.     

Postembryonic stages of Nucellicola holmanae Lamb et al., 1996 (copepoda, poecilostomatoida), an endoparasite of the dog whelk Nucella lapillus (gastropoda)

The external morphology of the first three larval stages of Nucellicola holmanae is described. These stages were cultured from eggs found with the adults in the viscera of dog whelks collected from Robin Hood's Bay, North Yorkshire. The nauplius develops within the whelk. It moults to a metanauplius which is released as a free-swimming stage. The metanauplius moults to a free copepodid stage which exhibits a combination of characters typical of the first, second and third copepodid stages of other poecilostomatoid copepods. The infective copepodid stage which locates and penetrates the host is visible through the integument of this free-swimming copepodid.     

Character phylogenies in Candacia and Paracandacia (Copepoda, Calanoida) and the inevitably paraphyletic nature of many nominal taxa above subspecies level

Examination of the phylogenetic structure of the family Candaciidae shows the genus Paracandacia to comprise a strongly modified branch emerging from the clade commonly denoted as Candacia. This has been confirmed by studying selected character phylogenies. It is argued that the resulting paraphyletic nature of Candacia auct., though in a cladistic context undesirable on theoretical grounds, has to be accepted as inevitable. Recent studies on molluscs and arthropods, viz., have demonstrated that the continuous origin of paraphyletic taxa from previously monophyletic ones is nothing but a naturally occurring process, intrinsically embodied in the course of evolution.     

Patterns in diversity and community structure of epipelagic copepods from the Brazil–Malvinas Confluence area, south-western Atlantic

Diversity and structure of epipelagic copepod communities were investigated using 70 zooplankton samples collected from the top 50 m of the Brazil–Malvinas Confluence area between 35° and 55°S. Biogeographic patterns were investigated using multivariate analysis. Biodiversity patterns were examined using different univariate indexes. Representatives of 35 species of copepods from 23 genera and 13 families were found. Two zones were delimited based on their copepod composition, one in the subtropical waters of the Brazil current, and the other in the subantarctic waters of the Malvinas current. Both environments displayed contrasting patterns of biodiversity depending upon which element is measured (regional species richness as well as mean point species richness were significantly higher in the subtropical group of stations, whereas taxonomic distinctness was significantly higher in the subantarctic community). Based on these contrasting results, we suggest the use of both kind of indexes when defining priority areas for conservation.     

Pigments, size and distribution of Synechococcus spp. in the Black Sea

Pigments, size and distribution of Phycoerythrin-containing unicellular cyanobacteria Synechococcus spp. within the euphotic zone were studied for the first time in April–May 1994 in the western and southwestern Black Sea by epifluorescence microscopy and flow-cytometry. Synechococcus was present in varying quantities at every station and depth studied. Surface spatial distribution of Synechococcus revealed that cells were much more abundant in offshore waters than near coastal regions under the direct influence of the Danube river. Minimum and maximum cell concentrations ranged between 9×10² and 1.45×10⁵ cells/ml at the surface, between 2×10³ and 1.23×10⁵ cells/ml at the chlorophyll sub-maximum layer, and between 1.3×10² and 3.5×10² at the nitrite maximum layer. Cells at the chlorophyll sub-maximum layer (based on in-situ fluorometer readings) fluoresce brighter and longer than the ones at the surface and lower depths. Spectral properties of chromophore pigment types of total 64 clonal isolates from different depths down to the lower layer of the euphotic zone (60 m) in the southern Black Sea coast revealed that all have type 2 phycoerythrobilin in common, lacking in phycourobilin. In vivo fluorescence emission maxima for the phycoerythrobilin were about the same (578 nm) for all isolates. All isolates examined showed in vivo absorption maxima at between 435 and 442 nm and at about 681 nm due to chlorophyll-a. Based on the flow cytometer mean forward light scatter data for size distribution, it could be concluded that cells at the surface mixed layer (0–10 m) were larger in cell size than the cells at lower depths (20–60 m).     

Exploring relationships between recruitment of European hake (Merluccius merluccius L. 1758) and environmental factors in the Ligurian Sea and the Strait of Sicily (Central Mediterranean)

This paper explores the relationships between the spatial patterns of the distribution of the young hakes of the year (YOY) and the oceanographical features in two areas of the Central Mediterranean (the Ligurian Sea and the Strait of Sicily), characterised by the occurrence of straits and channels. Comparative and correlative approaches were used to investigate coupling between biological and physical patterns. Density indices of the YOY were derived from annual trawl surveys from 1994 to 2004 in spring and autumn. Mean patterns of the YOY distributions were compared with the mesoscale oceanographical features reported in literature. No evident trends in recruitment strength were found in either areas. Inter-annual variability in YOY abundance in the Ligurian Sea was higher than in the Strait of Sicily. The location of nursery grounds in the study areas coincides with zones of relatively higher production, where upwelling and other enrichment processes regularly occur. The presence of predictable eddies and the frontal systems play a major role in the localization of nursery areas in the Strait of Sicily, maintaining their stable position throughout the years. The strongest transport of southern waters from the Tyrrhenian to the Ligurian Sea, due to the East Corsica Current, which is negatively correlated to winter North Atlantic Oscillation, is associated with the highest abundance of hake recruits in the nurseries of the Northern Ligurian Sea.     

Egg production and associated losses of carbon, nitrogen and fatty acids from maternal biomass in Calanus finmarchicus before the spring bloom

We present concurrent data on ingestion, egg production and the loss of maternal biomass in pre-spring bloom female Calanus finmarchicus incubated under conditions representative of those in situ in the North Atlantic. A balanced metabolic budget was constructed and used to examine the relative importance of ingestion and biomass for fuelling egg production during the incubations. Ingested carbon was not sufficient to meet the observed demands for egg production. More than 80% of the carbon utilised by the females was instead derived from their biomass. Fatty acid analysis demonstrated that the storage reserves, 20:1 (n−9) and 22:1 (n−11), were virtually absent before experimentation began, and therefore could not have been used to supply the carbon required for egg production during the incubations. The C:N mass-specific ratio of the biomass utilised was 4.1, suggesting that the females had instead catabolised protein in order to meet their metabolic demands. These results suggest that C. finmarchicus adopts a sacrificial reproductive strategy when food availability is low.