Search results for "Branchiopod"

An account on the non-malacostracan crustacean fauna from the inland waters of Crete, Greece, with the synonymization of Arctodiaptomus piliger Brehm…

2019

The Mediterranean bioregion is widely recognised as a biodiversity hotspot and its inland waters are among the species richest ecosystems of the northern hemisphere. However, the extent of such biodiversity has not been totally unravelled, especially in the Mediterranean islands. Here we present a first account of the crustaceans inhabiting 21 permanent and temporary ponds in Crete, the largest of the Greek islands and the fifth largest island in the Mediterranean Sea. The ponds, sampled between 2009 and 2018, cover all the island surface even though their number cannot be considered exhaustive to represent the entire non-malacostracan fauna of the island. Nevertheless, 46 taxa were identif…

The role of spatial and environmental factors as determinants of large branchiopod distribution in Tunisian temporary ponds

2015

Crustacean dynamics in two argillotrophic, temporary ponds (North-Western Sicily, Italy)

2004

Sicilian Temporary Ponds: An Overview of the Composition and Affinities of their Crustacean Biota

2009

Available data on Sicilian entomostracans allowed an initial characterization of the freshwater crustacean biota of the island and to formulate some hypotheses on its origin.The absence of supra-specific endemic taxa and the current regional distriburion of the investigated species suggest a late Pleistocene colonisation of the island by temperate taxa with a northern affinity, currently confined to the coolest areas of the island, followed by a Holocene arrival of thermophilous species coming from the Maghreb, which is still in progress. The importance of Sicily as a "crossroad" for the faunas of the circum-Mediterranean countries is thus confirmed.Unfortunately, and in spite of the EU dir…

Increase of rotifer diversity after sewage diversion in the hypertrophic lagoon, Albufera of Valencia, Spain

2001

The Albufera of Valencia is a large oligohaline hypertrophic lagoon, regulated by sluice gates according to the needs of the surrounding rice field cultivation. It is in a turbid state with permanent cyanobacterial blooms. A slight improvement was detected after diversion in the 1990s of part of the sewage flowing into it. After sewage diversion, we found that: (1) Chlorophyll concentration and rotifer densities decreased; (2) Rotifer proportions declined, due mainly to a relative increase in cladocerans; (3) Rotifer diversity increased. The two dominants of the 1980s, Polyarthra spp. in the colder period and Brachionus angularis in the warmer one, reverted after sewage diversion to a more …

Size distribution of Daphnia longispina in the vertical profile

1997

D. longispina of the meromictic lake El Tobar is a round-headed form. It never has a helmet, but in summer a small proportion of immature individuals (0.9–1.2 mm females and males) have one or two neck teeth. The size structure of this Daphnia population, as well as the vertical distribution and migration of different size-classes, were studied in September and November of 1991 and April of 1992. The large variation in mean size and size at first reproduction, as well as the occurrence of different patterns of vertical migration are interpreted as responses to different predator situations. At the end of April, when Daphnia mortality by visually hunting predators is dominating, a typical no…

Diel vertical migration by Daphnia longispina in a Spanish lake: Genetic sources of distributional variation

1995

Individuals of many zooplankton species undergo diel vertical migration in which they move toward the surface after sunset and return to deeper waters at dawn. However, even when vertical migration can be clearly demonstrated by mapping the distributions of individuals at noon and midnight, at any given time the population is usually scattered over ‘a broad range of depths. This paper focuses on a major potential source of the variance associated with depth distributions. We have used electrophoretic analysis of isozymes to identify “clones” of Daphnia longispina in a Spanish lake. In September 199 1, two clones constituted 5 5% of the individuals collected at noon and midnight on each oftw…

Zooplankton communities in doline lakes and pools, in relation to some bathymetric parameters and physical and chemical variables

1999

The zooplankton communities from several lakes and pools in three zones of a karstic area in central Spain were studied in spring and early autumn, in relation to morphometric, physical and chemical characteristics of the lakes. Zooplankton diversity was higher in autumn than in spring and it was positively correlated with lake size (area and depth) in spring, but not in early autumn. This effect is partially explained by the sharp zooplankton stratification in deep lakes, in early autumn. Some morphometric characteristics of lake basins were also correlated with the structure of zooplank- ton communities. Principal component analyses (PCA) and Two-Way Indicator Species Analysis (TWINSPAN) …

Effect of cadmium exposure on zinc levels in the brine shrimp Artemia parthenogenetica

1999

Zinc and cadmium have been reported as metabolic antagonists, such that high zinc intake afford animals some protection against the potentially toxic effects of cadmium exposure. There is considerable evidence to support a role of metallothioneins (MTs) in regulating or controlling the intracellular availability of essential metals and the non-essential metal. The effect of 24-h cadmium pre-exposure (10 mg Cd/l) on zinc concentrations in the brine shrimp Artemia parthenogenetica exposed to zinc (5 mg Zn/l) was studied. The zinc content of shrimps was not altered by cadmium. The homeostatic mechanism for zinc regulation appears not to be disturbed by cadmium exposure in shrimps kept in natur…

Impacts of reduced Lepidurus arcticus availability on brown trout life history traits in a mountain reservoir

2020

Lepidurus arcticus (the Arctic tadpole shrimp) is a vulnerable keystone species in Arctic and alpine water bodies where its occurrence and population size may influence the viability and life history traits of resident salmonids. Using data from a Norwegian mountain hydropower reservoir, Aursjoen, we illustrate how reduced availability of L. arcticus as prey resulted in the reduced condition, growth and delayed maturation of resident brown trout (Salmo trutta). We further link changes in the relative abundance of L. arcticus as prey to changing reservoir conditions, e.g. water level changes in the spring period, thereby establishing an indirect link between reservoir operation regimes and b…