Effects of aquatic macrophytes on water quality and phytoplankton communities in shallow lakes

We investigated aquatic macrophytes, water quality, and phytoplankton biomass and species composition in three shallow lakes with different levels of vegetation cover and nutrient concentration in Kushiro Moor, during August 2000. Trapa japonica can live in a wide range of nutrient levels. This species forms an environment with a steeper extinction of light, higher concentrations of dissolved organic carbon (DOC), lower concentrations of dissolved oxygen (DO) near the bottom, and lower concentrations of nitrate+nitrite and soluble reactive phosphorus (SRP) than other vegetation types. The pH was much higher in a Polygonum amphibium community, and the DO near the bottom did not decrease compared to a T.japonica community in the summer. The relationship between chlorophyll a and the limiting nutrient (total phosphorus (TP) when total nitrogen (TN):TPis 10 and TN/10 when TN:TP is <10) significantly differed between lakes with and without submerged vegetation. The chlorophyll a concentrations at a given nutrient level were significantly lower in water with submerged macrophytes than in water without them. Correspondence analysis showed that the difference in phytoplankton community structure across sites was largely due to the presence or absence of submerged macrophytes, and the ordination of phytoplankton species in the lakes with submerged macrophytes is best explained by environmental gradients of TN, chlorophyll, pH and SRP.     

Aquatic vegetation and largemouth bass population responses to water-level variations in Lake Okeechobee,Florida (USA)

A five-year study examined the responses of submerged aquatic vegetation (SAV), emergent vegetation, and largemouth bass (Micropterus salmoides) to variations in water level in a large lake in Florida, USA. SAV was assessed using a combined transect survey/spatial mapping approach, emergent vegetation was quantified with aerial photography and GIS, and bass were surveyed by electro-shocking. During the period leading up to this study (1995–1999), water levels were high in the lake, and the SAV was reduced in spatial extent and biomass, compared to its condition in the early 1990s. Spatial extent of emergent vegetation also was low, and largemouth bass surveys indicated low densities and failure to recruit young fish into the population. This was attributed to the lack of critical vegetative habitat. In spring 2000, the lake was lowered by discharging water from major outlets, and this was followed by a regional drought. Water levels dropped by 1m, and there was widespread development of Chara lawns in shoreline areas, with coincident increases in water clarity. There was some germination of vascular SAV, but Chara was the extreme dominant, such that structural complexity remained low. There was no substantive improvement in bass recruitment. During 2001, water levels declined further, and emergent plants germinated in exposed areas of the lake bottom. SAV was restricted to sites farther offshore, and continued to be dominated by Chara. There again was no bass response. In 2002, conditions changed when water levels increased to a moderate depth, flooding shoreline habitat to 0.5m. Vascular SAV increased in biomass and spatial extent, such that the community developed a high structural complexity. At the same time, emergent aquatic plants developed dense stands along the western shoreline. Largemouth bass had a strong recruitment of young fish for the first time in 5years. Recruitment continued to be successful in 2003, when spatial extent of SAV was somewhat reduced by higher water but total biomass and diversity remained high. These results demonstrate an important effect of inter-annual variation in water depth on the population dynamics of aquatic plants and fish in a subtropical lake.     

Comparisons of δ13C values in leaves of aquatic macrophytes from different habitats in Britain and Finland; some implications for photosynthetic processes in aquatic plants

Summary The ¹³C values of submerged aquatic plants from contrasting but relatively defined habitats, and the ¹³C values of emergent, floating and submerged leaves of dimorphic aquatic plants, were measured. In many instances the ¹³C values of dissolved inorganic carbon in the water were also measured. Plant ¹³C values in the vicinity of-40 to-50 were found in rapidly flowing spring waters with carbonate ¹³C values of-16 to-21, consistent with the notion that species such as Fontinalis antipyretica almost exclusively assimilate free CO₂ via RuP₂ carboxylase. Plant ¹³C values in the vicinity of-10 to-15 in sluggish water with carbonate ¹³C values of about-5 were observed, consistent with the notion that boundary layer diffusion and/or HCO₃ ^- uptake may determine the ¹³C value of submerged aquatic plants in these circumstances. Comparisons of ¹³C values of the same or related species growing in waters of similar carbonate ¹³C value but different flow rates confirmed this view; more negative ¹³C values were frequently associated with plants in fast moving water. In Britain, but not in Finland, the ¹³C values of submerged leaves of dimorphic plants were almost invariably more negative than in aerial leaves. The ¹³C value of carbonate from chalk streams and in acid springs indicate substantial inputs of respiratory CO₂, as opposed to atmospheric carbon. The contributions of these variations in ¹³C of the carbon source, and of isotope fractionation in diffusion, to the ¹³C value of submerged parts of dimorphic plants is discussed.     

Arsenic concentrations in water and fish from Chautauqua Lake,New York

Synopsis Arsenic persists in Chautauqua Lake, New York waters 13 years after cessation of herbicide (sodium arsenite) application and continues to cycle within the lake. Arsenic concentrations in lake water ranged from 22.4–114.81 g l^–1, = 49.0 ag l^–1. Well water samples generally contained less than 10 g l^–1 arsenic. Arsenic concentrations in lake water exceeded U.S. Public Health Service recommended maximum concentrations (10 g l^–1) and many samples exceeded the maximum permissible limit (50 g l^–1). Fish accumulated arsenic from water but did not magnify it. Fish to water arsenic ratios ranged from 0.4–41.6. Black crappie (Pomoxis nigromaculatus) contained the highest arsenic concentrations (0.14–2.04 g g^–1 ), X = 0.7 g g^–1) while perch (Perca flavescens), muskellunge (Esox masquinongy) and largemouth bass (Micropterus salmoides) contained the lowest concentrations (0.02–0.13 g g^–1). Arsenic concentrations in fish do not appear to pose a health hazard for human consumers.     

Phenotypic Differences in Buoyancy and Energetics of Lean and Siscowet Lake Charr in Lake Superior

At least two phenotypes of lake charr, Salvelinus namaycush, coexist in Lake Superior. A lean morph frequents the shallow inshore waters (< 50m) and the fat morph (siscowet) occupies the deeper offshore waters (50–250 m). The objective of this study was to determine if the elevated lipid concentration of siscowets reduces the costs of swimming in deep water. First, we modelled the effects of body composition (lipids) on the costs of swimming by lake charr, and then compared these theoretical results with empirical evidence obtained from Cesium 137-based estimates of food consumption, gross energy conversion, and swimming costs (activity multiplier). The attributes of growth, energy content (kJg^-1), lipid concentrations, and Cesium 137 concentration (Bqg^-1) were obtained from multimesh gillnet catches in eastern Lake Superior (1998 and 1999). The model showed that siscowet (fat) lake charr expended less energy than lean lake charr moving through the water column. Empirical evidence derived from Cesium 137 analysis confirmed that the activity multipliers of siscowets (fat) were less than those for lean charr. These findings support the view that the restoration of the fish community of the predominately deep water of the Great Lakes might be facilitated by the introduction of the fat phenotype.     

Seepage patterns, pore water, and aquatic plants: hydrological and biogeochemical relationships in lakes

This study documented linkages between lakeshore seepage fluxes, pore water chemistry, and aquatic plants in several lakes of the Adirondack Mountains region of New York, USA. Three replicate stations were set up along each of four different lake shorelines. From June through September 1998 and from snowmelt in April through August 1999, seepage flux was measured with seepage meters. Throughout this time period, lake surface water and pore water chemistry were monitored weekly to biweekly. At each station, leaf tissue chemistry of the water lily Nuphar variegatum was measured once in each year. Sediment chemistry and plant abundance were also measured once in 1998. We found that pore water concentrations of base cations, iron, and zinc were related to the direction, magnitude, and variability of seepage fluxes. Concentrations of base cations, iron, and zinc were both highest and most variable where seepage was low (0 to 50mLm^–2h^–1) in contrast to being more stable where seepage was highest and variable (–608 to 612mLm^–2h^–1). Leaf tissue chemistry and plant abundance were also related to seepage patterns. N. variegatum leaves had elevated zinc content at stations with low average discharge. Knowledge of seepage patterns helped to explain spatial patterns of elevated trace metal content in both pore water and plant tissues. Our work suggests that the hydrological process of lakeshore seepage exerts important controls on lakeshore biogeochemistry.     

Distribution and abundance of littoral benthic fauna in Canadian prairie saline lakes

The littoral benthos of 18 lakes in Alberta and Saskatchewan ranging in salinity from 3 to 126 (g1^–1 TDS) were investigated twice, in the spring and in the summer of 1986. Multiple Ekman dredge samples were taken at water depths of about 0.5, 1.0 and 2 metres in each transect. Two to three transects were used in each lake according to its estimated limnological diversity for a total of 114 stations. A total of 76 species was present varying from 29–31 species in the three lakes of lowest salinity (means of 3.1–5.55) to only 2 species in lakes exceeding 100. Species richness decreased rapidly in salinities greater than 15.Biomass maximum mean of 10.91 g m^–2 dry weight (maximum 63.0 g m^–2) occurred in culturally eutrophic Humboldt Lake (3.1) but one third as great in other low salinity lakes. However, biomass again increased to about 4.5 gm^–2 in two lakes of 15 As the salinity increased still further biomass declined steadily until a minimum of 0.0212 g m^–2 was recorded in most saline Aroma Lake (mean 119). Summer biomass (11 lakes) was greater than spring biomass (4 lakes) because some groups such as amphipods, corixids and ostracods became more abundant in summer. Wet weight biomass averaged 15.8 of dry weight biomass.Seasonality (spring or summer), sediment texture and organic matter content, water depth, pH, salinity (TDS) and the presence of aquatic plants ( plant cover) were considered in the matrix involving species dry weight biomass at each of 117 stations. TWINSPAN classification of the samples yielded a dendrogram with 18 indicator species. Successive dichotomies divided these indicator species into four main lake groups based on salinity, i.e., Group I: 3–10 (Gammarus, Glyptotendipes I, Chironomus cf. plumosus), Group II: 10–38%. (Hyalella, Enallagma,Bezzia), Group III: 38–63 (Hygrotus salinarius, Cricotopus ornatus), Group IV: >63 (Dolichopodidae, Ephydra hians). Each of these main groups was subdivided into smaller groups of lakes based on factors such as pH, seasonality (spring or summer species dominance), organic matter and plant cover. Depth of samples played no apparent role.     

Significance of bacterial ectoenzymes in aquatic environments

The report presents studies on temporal and spatial variations of kinetics (Vmax and Km) of bacterial ectoenzyme activity (-glucosidase - Glc, leucine aminopeptidase - Leu-amp) in the naturally eutrophic Plusee. Glc and Leu-amp activity were positively correlated with the flux of polymeric materials (polysaccharides, proteins) in the lake. Glc activity was low when algal populations grew actively, but during the algal bloom breakdown Glc activity increased rapidly. Leu-amp displayed the highest rates of activity in the epilimnion and was tightly coupled to bacterial production. The synthesis of studied ectoenzymes was under control of a repression/derepression mechanism. The significance of ectoenzymes for the transformation and bacterial utilization of organic matter, and their role in the microbial loop in aquatic environments is discussed.     

Cyanobacterial toxicity and migration in a mesotrophic lake in western Washington, USA

In fall 1997, the toxic cyanobacterium Microcystis aeruginosa was documented in Lake Sammamish (western Washington, U.S.A.) for the first time. Cyanobacterial activity and environmental conditions that may promote toxic cyanobacteria were investigated during summer and fall 1999. Development of toxic Microcystis was hypothesized to be due to runoff of nutrients from the watershed (external loading hypothesis) or from vertical migration of dormant cyanobacteria from the nutrient-rich sediments into the water column (cyanobacterial migration hypothesis). Microcystins were detected using an enzyme-linked immunosorbent assay during late August and early September 1999 despite low cyanobacterial abundance. Microcystin concentrations ranged between 0.19–3.8 g l^–1 throughout the lake and at all depths with the exception of the boat launch where concentrations reached 43 g l^–1. Comparison of the conditions associated with the toxic episodes in 1997 and 1999 indicate that Microcystis is associated with a stable water column, increased surface total phosphorus concentrations (> 10 g l^–1), surface temperatures greater than 22°C, high total nitrogen to phosphorus ratios (> 30), and increased water column transparency (up to 5.5 m). Migration of the cyanobacteria, Microcystis and Anabaena, occurred in both the deep and shallow portions of the lake. Microcystis dominated (89–99%) the migrating cyanobacteria with greater migration from the shallow station. External loading of nutrients due to the large rainfall preceding the 1997 toxic episode may have provided the nutrients needed to fuel that bloom. However, toxic Microcystis occurred in 1999 despite the lack of rain and subsequent external runoff. The migration of Microcystis from the nutrient-rich sediments may have been the inoculum for the toxic population detected in 1999.     

Ultrastructure of the stem of the aquatic plantCallitriche stagnalis L.

Summary The submerged stem ofCallitriche stagnalis L. has been studied by light and electron microscopy. The presence of plastids with an opaque body are noted in the parenchymatic cells near the conducting elements as well as many microtubules associated with polyribosomes and vesicles near the cell wall.It is of particular interest to note that the tracheids are connected to the pith lacuna and each other to form only one conducting cylinder, so that functionally theCallitriche stele seems to be a protostele. This reduction of the stele is probably due to the environment conditions, since by floral morphology this aquatic plant is considered an evolved species.     

First investigation of ultraoligotrophic alpine Lake Puma Yumco in the pre-Himalayas,China

Lake Puma Yumco is a typical alpine lake (altitude 5030m) located in the pre-Himalayas of Tibet, China, and this study was the first limnological investigation ever conducted on it. Lake Puma Yumco (28°34N, 90°24E) has the following morphometric properties: maximum length 31km, maximum width 14km, mean width 9km, shoreline 90km, surface area 280km², and shoreline development 1.5. Transparency was approximately 10m, even in the thawing season. The extinction coefficient of the lake water was calculated as 0.15m^–1. Annual maximum transparency was estimated from the depth of the Chara zone to be 30m. Dissolved oxygen was 7mg O₂ l^–1 and showed saturated values, and salinity was 360mgl^–1. The chemical type of the lake water was Mg-Ca-HCO₃-SO₄, and it was slightly alkaline in character. Total nitrogenous nutrients (sum of ammonia, nitrite, nitrate, and urea nitrogen), phosphate, and silicate were extremely low at 1, 0.02, and 9µM, respectively. Dissolved organic carbon, nitrogen, and phosphorus concentrations were 160, 11, and 0.08µM and the molar ratio was calculated as 2100:140:1. Chlorophyll a concentration was 0.2mgm^–3. Phytoplankton and zooplankton were dominated by Aphanocapsa sp. and Diaptomidae. Both nitrogen and phosphorus appear to be the limiting parameters for phytoplankton growth. Organic carbon and nitrogen contents in lake sediments were low and the sediments contained a large amount of CaCO₃. The grain size of sediment was that of silt-sand in most cases. The present results indicate that the pre-Himalayan alpine freshwater Lake Puma Yumco is an ultraoligotrophic lake.     

Age and growth,reproduction and diet of a sublittoral population of the rock goby Gobius paganellus (Teleostei,Gobiidae)

Colonisation of extremely acidic waters (pH 3) by aquatic angiosperms occurs widely, but is poorly documented. Unlike acid rain affected and other naturally acidic aquatic ecosystems, waters with pH 3 usually have a high conductivity, with high concentrations of SO₄ ^2- and often high concentrations of Fe³⁺, other heavy metal ions and Al³⁺. Where Fe³⁺ concentration is high, as in many mine waters, it provides a strong buffering system. In such waters, the biogeochemical Fe cycle exerts over water chemistry and the availability of nutrients and carbon for organisms. Biological activity is limited by low concentrations of phosphorus and inorganic carbon (DIC), which in this pH range is essentially all in the form of dissolved CO₂. A number of angiosperms grow in such waters including Phragmites australis, Typha spp. and Juncus bulbosus, though the last is the only one reported to grow totally submerged in waters with pH 3 . J. bulbosus occurs in many lignite mining lakes in Lusatia (north eastern Germany) with pH 3. The characteristics and possible survival strategies for this and other species are discussed.     

Submerged vegetation development in two shallow, eutrophic lakes

Submerged macrophyte vegetation in two shallow lakes in the Netherlands, Lake Veluwemeer and Lake Wolderwijd, has been affected by eutrophication in the late 1960's and 1970's. Recent changes in the vegetation occurred in the period following lake restoration measures. Between 1987 and 1993, the dominance of Potamogeton pectinatus decreased, while Charophyte meadows expanded over the same time interval. The pattern of change of the dominant macrophyte species might result from changes in the underwater light climate. Seasonally persistent clear water patches associated with the Chara meadows have been observed in the last few years. The interaction between submerged macrophyte vegetation succession and water transparency in the lakes is discussed.     

Influence of temperature and food availability on the ecological energetics of the giant scallop Placopecten magellanicus

Summary Gonad output, reproductive effort and residual reproductive value are greater in scallops (Placopecten magellanicus) from shallow water, where conditions are more favourable, than in scallops from deep water. Variation between years in these fitness correlates is also greater in shallow water scallops. High reproductive effort is associated with a greater reproductive cost, although in general reproduction in this species appears to be restrained, and only in older individuals from shallow water is there evidence of reckless reproductive behaviour. Reproductive effort increases as the animal grows older, but residual reproductive value is a maximum at age 4 years, after which it decreases with age owing to greater mortality. Localities vary in their suitability for scallop growth and reproduction, and at one Newfoundland site conditions in shallow water (10 m) are better than those in deep water (31 m). Scallops from the former have a greater fitness than those from the latter. The energy costs of reproduction have implications for life history variability in P. magellanicus, although for a considerable part of its lifetime the scallop is able to maximise gamete production in response to environmental factors (especially the food supply) without trading off reproduction against growth or maintenance.     

Diatom–environmental relationships and nutrient transfer functions from contrasting shallow and deep limestone lakes in Ontario, Canada

Diatom assemblages were analysed in the surface sediments of 44 alkaline lakes in south-western Ontario, Canada, and combined with a pre-existing 58 south-eastern Ontario lake set: (1) to determine if shallow, polymictic Ontario lakes contain different diatom assemblages from deeper, dimictic lakes, and if so, which environmental variables most influence assemblages; (2) to improve the existing transfer functions; (3) to construct and compare transfer functions separately for dimictic, deep lakes and for polymictic, shallow lakes. Polymictic and dimictic lakes covered a similar nutrient range (spring total phosphorus (TP)=4–54 g/l, spring total nitrogen (TN)=200–927 g/l; n=101) and spring pH levels (7.6–9; n=101). However, polymictic lakes were shallower (median mean depth = 2.9 m vs. 7.3 m in dimictic lakes). Benthic diatoms (average 60% relative abundance) dominated the polymictic lakes, whereas planktonic diatoms (average 60%) dominated dimictic lakes. A Canonical Correspondence Analyses with forward selection (p < 0.05, 999 Monte Carlo permutations) identified TP, alkalinity, watershed to volume ratios and lake depth as the most important measured environmental variables influencing diatom distribution in both polymictic and dimictic lakes. Additionally, pH was identified as an important variable in polymictic lakes, whereas TN was also forward selected in the dimictic lakes. Adding more lakes to the original southern Ontario calibration set improved the TN transfer function (r² _jack=0.42, root mean squared error of prediction (RMSEP)_jack=0.11 [log g TN/l]), although there was a high systematic error in the revised model (r² _residual = 0.48). However, the strongest TP model was derived from the polymictic lakes (r² _boot =0.44, RMSEP_boot=0.20 [log g TP/l]), which was the smallest lake set (n=30) with the lowest number of diatom species. The stronger TP model from the polymictic lakes may be partly due to the relatively low macrophyte cover in our polymictic lakes, which may lead to stronger benthic–pelagic coupling than in lakes with large macrophyte populations. Additionally, our study suggests that the Chrysophyceae cyst:diatom frustule ratio may be useful for indicating trends in TP levels of 35 g/l in alkaline lakes that are dimictic, but is not necessarily indicative of trophic state changes in shallow, polymictic lakes. Our study demonstrates that it may be important to construct separate diatom-based nutrient transfer functions for polymictic and dimictic lakes.     

A comparative study on planktonic ciliates in two shallow mesotrophic lakes (China): species composition, distribution and quantitative importance

The species richness and seasonal development of planktonic ciliates were studied and compared in two shallow mesotrophic lakes, one covered with dense submerged macrophytes, the other macrophyte poor. Considerable differences in ciliate species composition, dominant taxa, abundance and biomass were observed. Ciliates were much more species rich in the macrophyte-rich lake, while they were more abundant numerically in the macrophyte-poor lake. Altogether, 96 species, included in 53 genera, 14 orders were identified. Among them, 80 species (included in 45 genera, 14 orders) observed from the macrophyte-rich lake, against 49 species (36 genera, 12 orders) were from the macrophyte-poor lake. In the macrophyte-rich lake, the mean abundance and biomass were 13.5 cells ml^-1 and 547.10 g l^-1 f.w.; abundance and biomass were higher in spring and winter; naked oligotrichs dominated total ciliate abundance and Peritrichida dominated the biomass. In the macrophyte-poor lake, ciliate mean abundance and biomass were 35.5 cells ml^-1 and 953.39 g l^-1 f.w.; abundances peaked in autumn; Scuticociliates dominated the abundance and Tintinnids dominated the biomass. Possible causes for the observed differences are discussed.     

Bacilliform inclusions in cells of the proximal pars distalis in the pituitary of four species of Tilapia (Teleostei)

Summary Thin sections and replicas of freeze-etched pituitaries from six species of the teleostean family of Cichlidae were studied by electron microscopy. Four species belonging to the genus Tilapia exhibit rod-like structures, i.e., bacilliform inclusions (BI), about 1–2 m in length in cells of the proximal Pars distalis. The BI are found either isolated or fused in small groups. They are enclosed in an envelope similar to that of secretory granules. Both the BI and the secretory granules give a positive PAS-reaction.Abbreviations BI bacilliform inclusion - GTH gonadotroph hormone - STH somatotroph hormone - TSH thyrotroph hormone This research was supported by a grant from the National Council for Research and Development, Israel, and the GKSS Geesthacht-Tesperhude, Germany     

Relation between trace element levels in plasma and myocardium during coxsackievirus B3 myocarditis in the mouse

During most infections the plasma levels of trace elements change, but it is not clear if this reflects changes in the infected tissues. Coxsackievirus B3 (CB3) infection may result in viral replication, subsequent inflammation and changed trace element levels in the myocardium. In the present study, the trace element levels in the plasma and heart of adult male A/J mice were determined during the pre-inflammatory stage (day 4) of CB3 myocarditis for the following trace elements: aluminium (Al), arsenic (As), calcium (Ca), cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), selenium (Se), silver (Ag), vanadium (V) and zinc (Zn). The severity of the infection was assessed through clinical signs of disease and trace element levels were measured through inductively-coupled plasma mass-spectrometry (ICP-MS). In the heart, the levels decreased for V (59%; p<0.01), Co (38%; p<0.01), Al (81%; p< 0.01), As (66%; p<0.01) and Se (16%; p<0.01). Increased levels were detected for Mn (13%; p<0.05), Fe (48%; p<0.01), Cu (34%; p<0.01) and Ag (46%; p< 0.01). In the plasma, decreases were detected in the level of Zn (32%; p<0.05), whereas increases were seen in Mn (362%; p<0.05), Fe (272%; p<0.01), Co (71%; p<0.05), Cu (25%; n.s.) and Mg (43%; p<0.01) levels. A correlation was found between the levels in plasma and myocardium for Co (r _s=–0.636; p<0.05), Fe (r _s=0.764; p<0.05), Mn (r _s=0.682; p<0.05) and Mg (r _s=–0.791; p<0.05). Thus, determination of some of these trace elements in the plasma may be useful to indicate target tissue involvement in the early pre- inflammatory stage of an infectious disease. Some of these elements are important nutrients for the immune system, while others may be associated with the development of disease complications, such as cardiac arrhythmias.     

Alarm response of hatchlings of the apple snail, <Emphasis Type="Italic">Pomacea canaliculata</Emphasis> (Gastropoda: Ampullariidae), to aqueous extracts of other individuals

We examined how hatchlings of the freshwater snail, Pomacea canaliculata, responded to aqueous extracts of conspecific hatchlings. Three, 3-day-old hatchlings were macerated in deionized water (1mg hatchling per 1ml water). When 0.5ml of the aqueous extract was added to a test tube containing 10 hatchlings of the same age and 50ml of water, the hatchlings in the water began to crawl out of the water within 5min. The proportion of hatchlings that crawled out of the water approached 0.6–0.9 after 1h, but gradually decreased to 0.4 after 24h. The relatedness between the live and the macerated hatchlings had no significant influence on the response. Hatchlings of egg masses obtained either in the laboratory or in the wild responded similarly to aqueous extracts of hatchlings from either egg mass. This suggests that the conditions under which the egg masses were incubated or the conditions that their parents had experienced had no effect on the hatchlings response. When compared with experiments reported on other aquatic animals, we consider the behavior of the hatchlings to be an alarm response of escaping from predators.     

A manganese requirement for patulin biosynthesis by cultures of Penicillium urticae

Antibiotic production by submerged cultures of Penicillium urticae required manganese supplementation of the media. Thus, manganese supplementation (152 M) allowed accumulation of patulin to high concentrations (2 mol/mL), whereas manganese deficiency (1.53 M) resulted in the accumulation to similar levels of the first committed pathway intermediate, methyl-salicylic acid, without significant patulin accumulation. Preliminary studies suggest that a similar manganese effect may occur in other fungal species.