Abundance and spatial distribution of Artemia salina in Lake Abert,Oregon

In 1981–1982 Abert Lake had an area of 200 km², with a mean depth of 2.5 m and a total dissolved salt concentration of 82 gl^-1. The spatial distribution and abundance of the brine shrimp, Artemia salina, were monitored for 1981–1982. In 1981 during the midsummer months, with sampling primarily in the eastern side of Abert Lake, brine shrimp populations showed peak densities of 2–4 ind. 1^-1. In 1982, peak abundance occurred in early July and ranged between 5–8 ind. 1^-1. Lakewide estimates of brine shrimp derived from 14 collecting stations and assuming a uniform distribution over the lake resulted in estimates of lakewide abundance of 3 × 10¹¹ adults with a total biomass of 7 × 10⁶ kg. The major algal species in the lake was a benthic filamentous green alga (Ctenocladus circinnatus).     

International study on Artemia LXIII. Field study of the Artemia urmiana (Günther, 1890) population in Lake Urmiah, Iran

Lake Urmiah is a large (total surface 4750–6100 km² in recent times) thalassohaline hypersaline lake (150–180 g l^–1 in the period 1994–1996), located in northwestern Iran. It is the habitat of the endemic Artemia urmiana. Over the period July 1994–January 1996 a sampling campaign was organized: 36 fixed sampling stations, distributed over the entire lake's area, were sampled weekly to determine water temperature, salinity and transparency. At each occasion a filter net was dragged over a distance of 400 m in the superficial water layer to assess the density and composition of the Artemia population. A more limited sampling campaign focused on the annual fluctuations in chlorophyll concentration and on the reproductive behaviour of the brine shrimp population. Several stages of brine shrimp survived during winter months (water temperature 3°C) at low densities. Compared to available data for the Great Salt Lake, USA, Lake Urmiah shows a low algal biomass and overall low Artemia density. The increasing grazing pressure of the developing brine shrimp population in spring seems to prevent the phytoplankton from reaching high blooming concentrations, and oviparity is the dominant reproductive mode throughout the reproductive season.     

Food-web modification by an invertebrate predator in the Great Salt Lake (USA)

Summary During unusually wet years the salinity of the Great Salt Lake (Utah) decreased from above 100 g/L to 50 g/L. This allowed the predaceous insect Trichocorixa verticalis to invade the pelagic region of the lake and reach a mean summer density of 52/m³. Concurrent changes in the pelagic ecosystem were: a decrease in the dry biomass of the previously dominant filter-feeding brine shrimp Artemia franciscana from 720 to 2 mg/m³, the invasion of three other zooplankton taxa, a 10 × decrease in community filtration rate, a 20 × increase in chlorophyll a concentration, a 4 × decrease in water clarity and perhaps a decrease in soluble nutrients. Trichocorixa abundance was also inversely correlated with the abundance of Artemia along a salinity gradient in the lake's estuary. In a 9-d microcosm experiment Trichocorixa preyed on nauplii and decreased the total density of Artemia from 103 to 6/L. The reduction in Artemia allowed protozoans to increase 10–100 ×. Changes in chlorophyll and clarity were consistent with those observed in the lake. These results suggest that invertebrate predation may be an important factor structuring simple food webs such as those found in moderately saline lakes.     

Possible importance of algal toxins in the Salton Sea, California

In response to wildlife mortality including unexplained eared grebe (Podiceps nigricollis) die-off events in 1992 and 1994 and other mortality events including large fish kills, a survey was conducted for the presence of algal toxins in the Salton Sea. Goals of this survey were to determine if and when algal toxins are present in the Salton Sea and to describe the phytoplankton composition during those times. A total of 29 samples was collected for toxicity analysis from both nearshore and midlake sites visited biweekly from January to December 1999. Dinoflagellates and diatoms dominated most samples, but some were dominated by a prymnesiophyte (Pleurochrysis pseudoroscoffensis) or a raphidophyte (Chattonella marina). Several types of blooms were observed and sampled. The dinoflagellate Gyrodinium uncatenum formed an extensive, dense (up to 310000 cells ml^–1) and long-lasting bloom during the winter in 1999. A coccolithophorid, Pleurochrysis pseudoroscoffensis, occurred at high densities in surface films and nearshore areas during the spring and summer of 1999. These surface films also contained high densities of one or two other species (an unidentified scrippsielloid, Heterocapsa niei, Chattonella marina). Localized blooms were also observed in the Salton Sea. An unknown small dinoflagellate reached high densities (110000 cells ml^–1) inside Varner Harbor, and an unidentified species of Gymnodinium formed a dense (270000 cells ml^–1) band along part of the southern shoreline during the summer. Three species known to produce toxins in other systems were found. Protoceratium reticulatum (=Gonyaulax grindleyi) and Chattonella marina were found in several samples taken during summer months, and Prorocentrum minimum was found in low densities in several samples. Extracts of most samples, including those containing known toxic species, showed a low level (<10% mortality across all concentrations) of activity in the brine shrimp lethality assay and were not considered toxic. All sample extracts tested in the mouse bioassay showed no activity. One sample extract taken from the bloom of the small dinoflagellate was highly active (100% mortality across all concentrations) in the brine shrimp lethality assay, but the active material could not be isolated. While dense algal blooms are common at the Salton Sea, no evidence gathered in this study suggests that algal toxins are present within phytoplankton cells; however, toxins actively excreted by cells may have been missed. Blooms of phytoplankton likely contribute to wildlife mortality at the Salton Sea. Possible mechanisms including intoxication due to ingestion of feathers in grebes and waterlogging caused by changes in surface tension are discussed.     

Rotifer distributions in the coastal waters of the northeast Pacific Ocean

Absolute abundance of rotifers was assessed from 5 to 80 km across the continental shelf off of the southern Oregon coast (U.S.A.) in the northeast Pacific Ocean. A total of 97 vertically stratified water samples were collected at 49 stations from two depths, 3 and 30 m. Coastal upwelling conditions were indicated, with decreased temperature, increased salinity and higher chlorophyll-a concentrations closer to shore. Two rotifer genera, Synchaeta and Trichocercaoccurred within 16 km of shore with densities increasing closer to shore. Synchaeta reached densities of 64 inds l^–1 while Trichocerca was sparse (<1 inds. l^–1). Rotifers were most abundant at 3 m and the densest aggregations appear to be associated with estuary outlets, suggesting that estuaries may be important in exporting rotifers to nearshore coastal waters.     

Recolonization and possible recovery of Burrowing Mayflies (Ephemeroptera: Ephemeridae: Hexagenia spp.) in Lake Erie of the Laurentian Great Lakes

Burrowing mayflies of the genus Hexagenia spp. were widely distributed (ca. 80% of sites) and abundant (ca. 160 nymphs/m²) in the western basin of Lake Erie of the Laurentian Great Lakes in 1929–1930, prior to a period of anoxia in the mid 1950s. Nymphs were absent or rare in the basin between 1961 and 1973–1975. In 1979–1991, nymphs were infrequently found (13–46% of sites) in low abundance (3–40 nymphs/m²) near shore (<7.5 km from shore), but were absent or rare offshore (0–7% of sites at 0–1 nymphs/m²). Increased abundance occurred offshore between 1991 (0% of sites) and 1993 (52% of sites at 7/m²). Annual sampling, beginning in 1995, indicates that nymphs increased in both nearshore and offshore waters. By 1997, nymphs were found throughout the lake (88% of sites) at a mean density 40-fold greater (392/m²) than that observed in 1993 (11/m²). In 1998, the distribution of nymphs remained the same as 1997 (88% of sites) but density declined 3-fold (392 to 134/m²). These data indicate that mayflies have recolonized sediments of western Lake Erie and that their abundance may be similar to levels observed before their disappearance in the mid 1950s. However, prior to the mid 1950s, densities were greater in offshore than nearshore waters, but between 1979 and 1998 greater densities occurred near shore than offshore. In addition, there were two areas in the 1990s where low densities consistently occurred. Therefore, recovery of nymphs in western Lake Erie may not have been complete in 1998. At present we do not know the cause for the sudden recolonization of nymphs in large portions of western Lake Erie. Undoubtedly, pollution-abatement programs contributed to improved conditions that would have ultimately led to mayfly recovery in the future. However, the explosive growth of the exotic zebra mussel, Dreissena polymorpha, undoubtedly diverted plankton foods to bottom substrates which could have increased the speed at which Hexagenia spp. nymphs recolonized sediments in western Lake Erie in the 1990s.     

The emergence of Cochlodinium along the California Coast (USA)

A sudden and nearly synchronous emergence of the red tide forming dinoflagellate Cochlodinium along more than 800 km of California coastline was initially observed in late summer 2004. Thereafter high cell concentrations have been detected on an annual basis. Here, we present quantitative and semi-quantitative data indicating that Cochlodinium was uncommon in the phytoplankton community in California prior to 2004 and is now persisting as a more regular component and one that seasonally can cause red tides. The quantitative portion of this study was primarily conducted in Monterey Bay, where cell densities reached at least 6 × 10⁴ cells L⁻¹ during the initial outbreak. A semi-quantitative comparison of California coastal counties by the California Department of Health Services (CDHS) was also made: of the 15 counties surveyed (most with multiple sites per county), cells were detected only from Los Angeles County in the south to San Mateo County in the central region (seven counties), but not in the northern part of the state (six counties). Two counties in the central region of the state, San Luis Obispo and Santa Cruz, displayed intense and frequent periods of elevated Cochlodinium cell abundances. Although not observed in the state-wide CDHS survey, we occasionally found cells in San Diego County with densities up to 2.7 × 10⁴ cells L⁻¹. Though these colonial dinoflagellates have been recognized in California for over 80 years, with several “blooms” recorded prior to 2004, the species’ geographic range and abundance in recent years suggest significant shifts in the nearshore phytoplankton community of this region of the eastern Pacific.     

Patterns in pelagic and benthic nanoflagellate densities in the coastal upwelling system along the Banc d'Arguin,Mauritania

We studied spatial variation in abundance of marine benthic and pelagic heterotrophic nanoflagellates in relation to abundances of autotrophic flagellates, bacteria and cyanobacteria in an upwelling area off the Banc d'Arguin, Mauritania.There was enormous spatial variation in densities. In the sediments these ranged from 8–219 × 10³ cm^–3 for heterotrophic flagellates. Maximum values are in the range of those for temperate shallow marine bottoms. Low densities (< 20 × 10³) were confined to the deep stations (> 1000 m). Over the shelf (10–100 m depth) densities were high but related to grain size rather than to concurrent upwelling phenomena or to the abundance of benthic macrofauna.Pelagic flagellate abundance appeared to be more indicative of contemporary hydrographic conditions, most obvious by an increase in the ratio heterotrophic/autotrophic nanoflagellates away from the area of most intense upwelling.     

Re-appearance of rotifers in hypersaline Mono Lake, California, during a period of rising lake levels and decreasing salinity

The surface elevation of Mono Lake, California, rose 2 m and mixed-layer salinities declined about 5 g kg^–1 during the 3 years (1995–1997) following the decision to restrict water diversions out of the Mono Basin. Abundant (18000 m^–2) Hexarthra jenkinae de Beauchamp were noted in pelagic samples in October 1997 after three decades of absence or very low abundance. Abundance subsequently increased to 100000 m^–2 in December 1997 before declining to low numbers through 1998 and 1999. The re-appearance of Branchionus plicatilis Müller in pelagic samples occurred in September 1998. B. plicatilis areal abundance increased to 15000 m^–2 in October–December of both 1998 and 1999 but was low throughout the rest of the year. Both rotifers were noted in nearshore ponds, but were only abundant in those with salinities below 53 g kg^–1. During 1998–1999 when the salinities of the upper water column were 73–75 g kg^–1, less saline shoreline habitats may have been seeding the offshore rotifer populations.     

Bioturbation by Nereis sp. and its effects on the phosphate flux across the sediment-water interface in the Palmones River estuary

The effects of Nereis sp. on the flux of dissolved phosphate across the sediment-water interface has been studied in Palmones River estuary using benthic flux-chambers and intact cores. Diffusive fluxes of phosphate were calculated from pore water gradient concentration and compared with those obtained from benthic chambers experiments. The high abundance of Nereis in the upper sediment layers appears to play an important part in the dissolved oxygen profiles in the overlying water, but had no effect on the redox potential. A negative relationship was found between the Nereis abundance and the phosphate gradient; this gradient ranged between 40 µmol 1^–1 cm^–1 with 340 Nereis individuals m^–2 and 20 µmol 1^–1 cm^–1 with 900 Nereis individuals m^–2. The ratio of the in situ flux to the flux gradient concentration for dissolved phosphate increased with the abundance of Nereis (from 1.7 at low abundance to 5.8 at high abundance).     

Strong small-scale temporal bacterial changes associated with the migrations of bloom-forming dinoflagellates

Bacterial abundances in nearshore Mediterranean planktonic environments tend to change seasonally by 10-fold. Strong daily changes in bacterial abundance, at least as large as seasonal range, occurred in the presence of large dinoflagellate populations performing daily vertical migrations. The daily variability of heterotrophic bacteria was associated with the daily migrations of a bloom of Alexandrium taylori in La Fosca Bay, and Gymnodinium impudicum in Barcelona harbor. Bacterial abundance in surface waters can change daily as much as from 1 × 10⁶ to 5 × 10⁶ with apparent net change rates of 0.24 h⁻¹. We suggest that the migrating dinoflagellates create microstructures exploited by the bacteria, and that the large algal populations (>10⁶ cells l⁻¹) make this microstructure visible with conventional sampling protocols. We also show evidence of the link between dinoflagellate abundance and relative bacterial activity in these waters, as measured by the percentage of bacteria with high nucleic acid content.     

Distribution patterns and predation risk of the coexisting cladocerans Bythotrephes longimanus and Leptodora kindtii in a large lake – Lake Constance

The distributions of the coexisting, planktonic, predatory cladocerans Bythotrephes longimanus and Leptodora kindtii were studied at four different stations (Langenargen-Arbon, Fischbach-Uttwil, Bregenzer Bucht and Zeller See) of a great lake, Lake Constance. The stations Langenargen-Arbon and Fischbach-Uttwil are deep (>200 m) with a high density of the coregonid fish Coregonus lavaretus, the stations Bregenzer Bucht and Zeller See are shallow (<60 m) with lower densities of coregonid fish. B. longimanus was present in the pelagic zone from mid May to November at all stations. L. kindtii generally appeared slightly later in the year than B. longimanus. Peak abundances of B. longimanus with more than 5000 ind. m^–2 (Langenargen-Arbon) appeared in late spring. During summer, when predation pressure by fish is high, abundance of B. longimanus decreased gradually. In contrast, L. kindtii displayed maximum abundances with more than 18 000 ind. m^–2 (Zeller See) in summer. During the summer months, B. longimanus lived in greater depths than L. kindtii. Differences of vertical distribution between both species were most pronounced at the deep stations (Langenargen-Arbon, Fischbach-Uttwil). Analysis of stomachs of the planktivorous fish Coregonus lavaretus showed that B. longimanus was preferred by C. lavaretus over all other prey; Ivlev's selectivity index was 0.97–0.99. Due to this high positive selection for B. longimanus by coregonids, it is surprising that the cladoceran could maintain its existence since the first recordings in 1877. Spatial refuge or indigestible resting eggs may be the underlying mechanism for this phenomenon.     

Effect of water-borne copper on respiratory and cardiac function during the early ontogeny of the brine shrimp,Artemia franciscana Kellogg 1908 (Branchiopoda: Anostraca)

There was no direct effect of copper on the ontogeny or function of the heart of the brine shrimp Artemia franciscana in sea water (salinity= 36 mg·ml^-1, 25°C). There was, however, an indirect effect as an increase in copper concentration resulted in a reduced growth rate. There was no difference between the critical O₂ tensions of newly hatched (stage 0/1) nauplii of control and treated (<0.32 and 10.11 mol·l^-1 copper, respectively) individuals. However by developmental stages 4–6, when both the heart and thoracic gills are in the process of differentiating, respiratory performance had improved (i.e. critical O₂ tension decreased from 6.27±0.45 to 4.69±0.24 kPa) in control but not in copper-treated individuals. It is suggested that respiratory impairment of stages 4–6 individuals is unlikely to be related to differences in cardiac performance or cellular respiration. Instead it may be related to metal-related damage to newly differentiating gill tissue and/or by copper in some way compromising the normal ontogenic shift in haemoglobin O₂ affinity. Copper-related respiratory impairment develops at a critical point in brine shrimp organogenesis when a good supply of O₂ is essential for normal development and if compromised may reduce the ability of this species to survive copper exposure.Abbreviations BL body length - BW body weight - HR heart rate - HM heavy metals - SW sea water - P _c critical oxygen tension     

The vertical distribution and abundance of <Emphasis Type="Italic">Gammarus lacustris</Emphasis> in the pelagic zone of the meromictic lakes Shira and Shunet (Khakassia,Russia)

The vertical distribution and abundance of Gammarus lacustris in the pelagic zone of two fishless meromictic lakes, L. Shira and L. Shunet, in Southern Siberia (Russia), was studied with the underwater video recording system and using vertical hauls. In both lakes, during summer stratification, Gammarus was distributed non-homogenously, with a stable peak in the metalimnion. The average depth of Gammarus population in the pelagic zone was significantly correlated with the depth of the thermocline. Gammarus abundances obtained using vertical plankton hauls with net were quite comparable with those obtained from video records. The peak abundance of Gammarus in the pelagic zone of the lakes observed with underwater video amounted up to 400 individuals m⁻², while the peak animal densities in the metalimnion reached 50 ind. m⁻³. The data are compared with previously published abundances of Gammarus in the littoral of Lake Shira. Both littoral and pelagic can be equally important habitats for amphipods in meromictic lakes. The absence of fish in the pelagic zone, high oxygen concentration, low water temperature, increased seston concentration, elevated water density in the metalimnion and the anoxic hypolimnion can be the most probable combination of factors that are responsible for the peak of Gammarus in the metalimnion of these lakes.     

Growth, survival, and starvation resistance of Colorado squawfish larvae

Synopsis Growth and survival of Colorado squawfish, Ptychocheilus lucius, larvae under fluctuating 18, 22, and 26° C (5° C diel fluctuations) and constant 18, 22, 26° C, and 30° C temperature conditions and ration size corresponding to 12.5, 28,64,142, 320 brine shrimp nauplii fish^–1 day^–1 determined from laboratory experiments. Growth was optimal at 31° C and high at temperatures of 26° C to 30° C, at the highest food abundance. Lowest growth was under lowest food rations and highest temperatures. Growth of Colorado squawfish larvae declined substantially at temperatures < 22° C. Neither growth nor survival was significantly different between fluctuating or constant regimes. Survival of Colorado squawfish larvae was highest (95%) at 26.2° C and 235 nauplii fish^–1 day^–1 and high at temperatures of 20 to 30° C with food abundance > 180 nauplii fish^–1 day^–1. Survival was lowest when food abundance was low and temperature was high. Highest mortality occurred more than 20 days after experiments began and mortalities occurred sooner in higher than lower temperatures. Colorado squawfish larvae denied food for 5, 10, or 15 d after first feeding could have begun (6 d), had survival greater than 87 % which was equivalent to continuously fed controls. Survival of fish denied food for 17.5 d after feeding could have begun declined from 84% before feeding to 57% after feeding. Point of no return was estimated between 17.5 and 20 d. Colorado squawfish have relatively high starvation resistance. Low, stable flows that simulate natural hydrographs may enhance growth, survival, and recruitment of early life stages of Colorado squawfish by increasing water temperature and food abundance in regulated rivers of the Colorado River basin.     

Competition between Brachionus calyciflorus Pallas and Brachionus patulus (Müller) (Rotifera) in relation to algal food concentration and initial population density

Competitive laboratory experiments between Brachionus calyciflorus and B. patulus were conducted at low (1×10⁶ cells ml^–1) and high (3×10⁶ cells ml^–1) densities of Chlorella vulgaris and four initial inoculation densities (numerically, 100% B. calyciflorus; 75% B. calyciflorus + 25% B. patulus; 50% each of the two species; 25% B. calyciflorus + 75% B. patulus and 100% B. patulus). Population densities were enumerated and the medium was changed daily for 20 days. B. patulus was a superior competitor in low food density regardless of inoculation density. At high food density, B. calyciflorus showed higher population growth in the first week but thereafter was outcompeted by B. patulus regardless of initial density. When grown alone, B. calyciflorus reached peak abundances (mean ± standard error) of 31±3 and 81±7 individuals ml^–1 at low and high food densities, respectively. The corresponding values for B. patulus were 130±2 and 306±13. The adverse effects of B. patulus on the peak abundances of B. calyciflorus were higher at low food concentration. Data on egg ratios (eggs female^–1) revealed an inverse relation with population abundance of both tested rotifer species. Our results indicated that the rate of population increase of a species was not a good indicator of its competitive ability. Instead, the ability to reproduce under continuously diminishing food resources (until a threshold level) was responsible for the competitive edge of B. patulus over B. calyciflorus. This was further influenced by the relative inoculation densities of the tested rotifer species and the offered food densities.     

Fish biology and fisheries ecology of the Salton Sea, California

Studies of the fisheries ecology and fish biology of the Salton Sea, California, were conducted in 1999 and 2000 using 50 m gill nets in river, nearshore, pelagic, and estuarine areas. Total lengths and weights were measured for all fish captured, and sub-samples were dissected for gonad weights and aging. Ten fish species were captured of which a hybrid tilapia (Oreochromis mossambicusx O. urolepis hornorum) was dominant by number and weight. Nearshore and estuarine areas had highest catch rates (over 11 kg h^–1 net^–1 for tilapia). Rivers were richest in the number of species (6 of 10 species were exclusively riverine), but lowest in fish abundance. Orangemouth corvina (Cynoscion xanthulus), bairdiella (Bairdiella icistia), sargo (Anisotremus davidsoni), and tilapia grew faster, but had shorter life spans than conspecifics elsewhere and Salton Sea conspecifics of 50 years ago. Reproduction occurred mostly in the nearshore and estuarine areas. Onset of reproduction of bairdiella and sargo was in the spring and extended through the beginning of summer. Reproduction of orangemouth corvina started in the summer and of tilapia in the spring. Reproduction of orangemouth corvina and tilapia extended through the fall. Gender ratios of tilapia were skewed toward males in all areas, except the rivers, where females predominated. All four species aggregated along the nearshore and estuarine areas in the summer when dissolved oxygen in the pelagic area was limited. Any restoration alternative for the Salton Sea should consider areas close to shore as primary areas for fish reproduction and survival.     

A comparison between predation effects on zooplankton communities by Neomysis and Chaoborus

Community level effects of predation by two invertebrate predators, the opossum shrimp (Neomysis intermedia), and the larva of the phantom midge (Chaoborus flavicans) were studied and compared. N. intermedia appeared abundantly in the shallow eutrophic Lake Kasumigaura and had a significant impact on the zooplankton community. The predation pressure by Neomysis was highest on cladocerans, followed by rotifers, and finally copepods. At high densities (maximum nearly 20 000 individuals m^–2), Neomysis excluded almost all cladocerans, rotifers and copepods from the lake.Zooplankton communities were established in experimental ponds, into which C. flavicans was introduced. The predator's density was around 1 individual l^–1, and was probably controled by cannibalism. Although Chaoborus larvae feed on various zooplankton species, their predation impact on zooplankton populations was markedly selective. They eliminated medium- and small-sized cladocerans and calanoid copepods from the ponds, but rotifers increased.Although the feeding selectivities of Neomysis and Chaoborus individuals were similar, the predation effects on zooplankton communities by the two predators were different.     

Cytotoxic 16-β-[(d-xylopyranosyl)oxy]oxohexadecanyl triterpene glycosides from a Malagasy plant, Physena sessiliflora

Brine shrimp lethality assay-guided separation of the MeOH extract of leaves of Physena sessiliflora, which is endemic to Madagascar, afforded eight triterpene glycosides, Physenoside S1–4 and 16-β-[(d-xylopyranosyl)oxy]oxohexadecanyl homologues, Physenoside S5–8. Structural elucidation of these compounds was based on both spectroscopic analyses and chemical properties. Physenoside S7 and S8 have significant cytotoxic activities in the brine shrimp lethality assay.     

Ecological observations and biomass proximate composition of the brine shrimp Artemia (Crustacea: Anostraca) from Pichilingue,Baja California Sur,México

The brine shrimp, most probably Artemia franciscana occurs in the solar salt plant (`salina') of Pichilingue (24°15N and 110°20W, total area about 10 ha), Baja California Sur, México. During the periods September 1999 to March 2000 and June 2000 to March 2001, salinity and temperature were determined weekly in selected evaporation ponds, as were the biological parameters of Artemia biomass, size of adult females and males, and monthly the biochemical composition of dried Artemia biomass. An explosive growth of Artemia was observed during moderate salinity levels (80–120 g l^–1), reaching a standing crop level of 300 kg wet weight ha^–1. With increasing salinity, biomass production and the size, especially of the females, decreased drastically, probably due to limited availability of natural food and to environmental stress. Brine shrimp survived up to a salinity of 270 g l^–1. Despite wide variations in the environmental conditions, the proximate analysis of Artemia biomass showed only small differences, with the exception of the crude fibre content.