Abundance and distribution of Ulva microscopic propagules associated with a green tide in the southern coast of the Yellow Sea

The presence of Ulva microscopic propagules may play an important role in the rapid development of high-biomass blooms of green algae in the Yellow Sea. Six cruises were conducted, to determine the abundance and distribution of Ulva microscopic propagules associated with a green tide that developed in the southern coastal waters of the Yellow Sea from April to August, 2012. Results indicated that Ulva microscopic propagules were widespread in these waters, with the highest density being up to 4800 ind. L⁻¹, prior to the appearance of the green tide in April. High densities were also widely distributed along the coast during May and June, after the appearance of the floating green tide. The quantity of Ulva microscopic propagules significantly decreased when the floating green tide declined in July, reaching densities of up to 162 ind. L⁻¹, following the disappearance of the floating green tide in August. Quantitative studies on the distribution patterns of Ulva microscopic propagules along the southern coast of the Yellow Sea indicated a significant correlation between density and salinity, turbidity and nutrient concentrations. Temporal and geographical distribution patterns of Ulva microscopic propagules were also significantly affected by the presence of a large biomass of attached, or floating, Ulva species algae.     

Assessment of spatial distribution and cysts resources of Artemia in late autumn in Dangxiong Co salt lake

Based on the vertically interval sampling in 25 sampling sites in Dangxiong Co salt lake in 2011, a preliminary investigation on population spatial distribution and cysts resources of Artemia in the lake has been conducted. The study achieves four new progresses. First, the average density of Artemia and Artemia cysts in the lake is 4.157 × 10³ ind. m⁻² and 8.069 × 10⁴ ind. m⁻², respectively. Among Artemia, the adults account for 60.31%; Second, different from other salt lakes in horizontal distribution, the Artemia population mainly distributes in the open water, only a little in the shallow water, and there is no distribution in the longshore area in the north part and the estuary region; Third, in vertical distribution, 44.24% of individuals intensively distribute in the upper water layer within 2.0 m, especially 0–0.2 m, where the average density of Artemia and cysts are maximum (129.488 ind. L⁻¹ and 5.728 ind. L⁻¹, respectively). A decrease of distribution density is accompanied by an increase of water depth basically, the percentage of Artemia and cysts decrease to 0.68% and 4.60%, respectively; Fourth, the cysts resources of 14.96 t in the lake are assessed using contour map. 66.35% of them distributed in 0.0–2.0 m water layer and 49.06% concentrate in the 18.21% areas of the central water; Fifth, quantity of cysts suitable for development in the lake is 2.399 ± 0.320 t, with an upper limit of 0.879 t. The study can provide a reference for the sustainable development and exploitation of Artemia in Dangxiong Co salt lake.     

Patch dynamics of the Mediterranean seagrass Posidonia oceanica: Implications for recolonisation process

Patch dynamics of the Mediterranean slow-growing seagrass Posidonia oceanica was studied in two shallow sites (3–10 m) of the Balearic Archipelago (Spain) through repeated censuses (1–2 year⁻¹). In the sheltered site of Es Port Bay (Cabrera Island), initial patch density (October 2001) was low: 0.05 patches m⁻², and the patch size (number of shoots) distribution was bimodal: most of the patches had less than 6 shoots or between 20 and 50 shoots. Mean patch recruitment in Es Port Bay (0.006 ± 0.002 patches m⁻² year⁻¹) exceeded mean patch loss (0.001 ± 0.001 patches m⁻² year⁻¹), yielding positive net patch recruitment (0.004 ± 0.003 patches m⁻² year⁻¹) and a slightly increased patch density 3 years later (July 2004, 0.06 patches m⁻²). In the exposed site of S’Estanyol, the initial patch density was higher (1.38 patches m⁻², August 2003), and patch size frequency decreased exponentially with size. Patch recruitment (0.26 patches m⁻² year⁻¹) and loss (0.24 patches m⁻² year⁻¹) were high, yielding a slightly increased patch density in the area 1 year later (October 2004, 1.40 patches m⁻²). Most recruited patches consisted of rooting vegetative fragments of 1–2 shoots. Seedling recruitment was observed in Summer 2004 at both sites. Episodic, seedling recruitment comprised 30% and 25% of total patch recruitment in Es Port Bay and S’Estanyol, respectively. Patch survival increased with patch size and no direct removal was observed among patches of 5 shoots or more. Most patches grew along the study, shifting patch distribution towards larger sizes. Within the size range studied (1–150 shoots), absolute shoot recruitment (shoots year⁻¹) increased linearly with patch size (R² = 0.64, p < 4 × 10⁻⁵, N = 125), while specific shoot recruitment was constant (about 0.25 ± 0.05 year⁻¹), although its variance was large for small patches. Given the slow growth rate and the high survival of patches with 5 or more shoots, even the low patch recruitment rates reported here could play a significant role in the colonisation process of P. oceanica.     

Does the tropical agricultural matrix bear potential for primate conservation? A baseline study from Western Uganda

As for most large mammals, conservation research on primates usually focuses on protected areas, and yet not much is known about primate communities in land-use systems in the absence of hunting. Using line transects, we estimated population densities for four primate species in a mixed agroforest landscape up to a distance of 4000 m from a forest reserve, in a region where no primate hunting takes place. We then modelled encounter rates and cluster size in relation to landscape parameters by means of bivariate analysis and Generalised Linear Models (GLMs). Black-and-white colobus (Colobus guereza) were most common, with confidence intervals for density estimates of 31.1–62.8 individuals/km². Red-tailed monkeys (Cercopithecus ascanius) and blue monkeys (Cercopithecus mitis) occurred at 15.2–37.9 ind/km² and 13.9–36.7 ind/km² respectively, and chimpanzees (Pan troglodytes) at 1.0–2.8 ind/km². Chimpanzee nest numbers and distribution appeared to be significantly constrained by transect forest coverage, forest coverage within 500 m and distance from the main forest, whereas monkey sightings were generally less restricted by landscape variables. The considerable population density of monkeys suggests that, in the absence of hunting, mixed agroforest systems may play a relevant role in primate conservation and highlight that it is useful to consider primate ecology in land sharing approaches to conservation.     

Shell productivity of the large benthic foraminifer Baculogypsina sphaerulata,based on the population dynamics in a tropical reef environment

Carbonate production by large benthic foraminifers is sometimes comparable to that of corals and coralline algae, and contributes to sedimentation on reef islands and beaches in the tropical Pacific. Population dynamic data, such as population density and size structure (size-frequency distribution), are vital for an accurate estimation of shell production of foraminifers. However, previous production estimates in tropical environments were based on a limited sampling period with no consideration of seasonality. In addition, no comparisons were made of various estimation methods to determine more accurate estimates. Here we present the annual gross shell production rate of Baculogypsina sphaerulata, estimated based on population dynamics studied over a 2-yr period on an ocean reef flat of Funafuti Atoll (Tuvalu, tropical South Pacific). The population density of B. sphaerulata increased from January to March, when northwest winds predominated and the study site was on the leeward side of reef islands, compared to other seasons when southeast trade winds predominated and the study site was on the windward side. This result suggested that wind-driven flows controlled the population density at the study site. The B. sphaerulata population had a relatively stationary size-frequency distribution throughout the study period, indicating no definite intensive reproductive period in the tropical population. Four methods were applied to estimate the annual gross shell production rates of B. sphaerulata. The production rates estimated by three of the four methods (using monthly biomass, life tables and growth increment rates) were in the order of hundreds of g CaCO₃ m⁻² yr⁻¹ or cm⁻³ m⁻² yr⁻¹, and the simple method using turnover rates overestimated the values. This study suggests that seasonal surveys should be undertaken of population density and size structure as these can produce more accurate estimates of shell productivity of large benthic foraminifers.

     

Differences in the photoacclimation and photoprotection exhibited by two species of the ciguatera causing dinoflagellate genus,Gambierdiscus

In culture, Gambierdiscus spp. have been shown to prefer irradiances that are relatively low (≤250 μmol photons m⁻² s⁻¹) versus those to which they are frequently exposed to in their natural environment (>500 μmol photons m⁻² s⁻¹). Although several behavioral strategies for coping with such irradiances have been suggested, it is unclear as to how these dinoflagellates do so on a physiological level. More specifically, how do long term exposures (30 days) affect cell size and cellular chlorophyll content, and what is the photosynthetic response to short term, high irradiance exposures (up to 1464 μmol photons m⁻² s⁻¹)? The results of this study reveal that cell size and chlorophyll content exhibited by G. carolinianus increased with acclimation to increasing photon flux density. Additionally, both G. carolinianus and G. silvae exhibited reduced photosynthetic efficiency when acclimated to increased photon flux density. Photosynthetic yield exhibited by G. silvae was greater than that for G. carolinianus across all acclimation irradiances. Although such differences were evident, both G. carolinianus and G. silvae appear to have adequate biochemical mechanisms to withstand exposure to irradiances exceeding 250 μmol photons m⁻² s⁻¹ for at least short periods of time following acclimation to irradiances of up to 150 μmol photons m⁻² s⁻¹.     

Population densities,group size and biomass of ungulates in a lowland tropical rainforest forest of the eastern Himalayas

Large ungulate population monitoring is a crucial wildlife management tool as ungulates help in structuring and maintaining the large carnivore populations. Reliable data on population status of major ungulate prey species are still non-existent for most of the protected areas in the Indian part of the eastern Himalayan biodiversity hotspot. Twenty transects were monitored over a period of three years (2009–2011) totaling 600 km with an average length of 2 km. The estimated mean density of ungulates was 17.5 km⁻² with overall density of 48.7 km⁻². The wild pig Sus scrofa had the highest density (6.7 ± 1.2 km⁻²) among all the prey species followed by barking deer Muntiacus muntjak (3.9 ± 0.6 km⁻²), sambar Rusa unicolor (3.8 ± 0.5) and gaur Bos gaurus (3.5 ± 0.9 km⁻²). The estimated total ungulate biomass density was 2182.56 kg km⁻². This prey biomass can support up to 7.2 tigers per 100 km⁻². However, with two other sympatric carnivores sharing the same resources, the actual tiger numbers that can be supported will be lower. The estimated minor prey species was 31 km⁻² significantly 30.6% crop damages were reported by wild pig (p = 0.01) and 35.4% was elephant (p = 0.004). This data on ungulate densities and biomass will be crucial for carnivore conservation in this understudied globally significant biodiversity hotspot.     

Proton production from nitrogen transformation drives stream export of base cations in acid-sensitive forested watersheds

The biogeochemical cycles of nitrogen (N) and base cations (BCs), (i.e., K⁺, Na⁺, Ca²⁺, and Mg²⁺), play critical roles in plant nutrition and ecosystem function. Empirical correlations between large experimental N fertilizer additions to forest ecosystems and increased BCs loss in stream water are well demonstrated, but the mechanisms driving this coupling remain poorly understood. We hypothesized that protons generated through N transformation (PPR_N)—quantified as the balance of NH₄⁺ (H⁺ source) and NO₃⁻ (H⁺ sink) in precipitation versus the stream output will impact BCs loss in acid-sensitive ecosystems. To test this hypothesis, we monitored precipitation input and stream export of inorganic N and BCs for three years in an acid-sensitive forested watershed in a granite area of subtropical China. We found the precipitation input of inorganic N (17.71 kg N ha⁻¹ year⁻¹ with 54% as NH₄⁺–N) was considerably higher than stream exported inorganic N (5.99 kg N ha⁻¹ year⁻¹ with 83% as NO₃⁻–N), making the watershed a net N sink. The stream export of BCs (151, 1518, 851, and 252 mol ha⁻¹ year⁻¹ for K⁺, Na⁺, Ca²⁺, and Mg²⁺, respectively) was positively correlated (r = 0.80, 0.90, 0.84, and 0.84 for K⁺, Na⁺, Ca²⁺, and Mg²⁺ on a monthly scale, respectively, P < 0.001, n = 36) with PPR_N (389 mol ha⁻¹ year⁻¹) over the three years, suggesting that PPR_N drives loss of BCs in the acid-sensitive ecosystem. A global meta-analysis of 15 watershed studies from non-calcareous ecosystems further supports this hypothesis by showing a similarly strong correlation between ∑BCs output and PPR_N (r = 0.89, P < 0.001, n = 15), in spite of the pronounced differences in environmental settings. Collectively, our results suggest that N transformations rather than anions (NO₃⁻ and/or SO₄²⁻) leaching specifically, are an important mediator of BCs loss in acid-senstive ecosystems. Our study provides the first definitive evidence that the chronic N deposition and subsequent transformation within the watershed drive stream export of BCs through proton production in acid-sensitive ecosystems, irrespective of their current relatively high N retention. Our findings suggest the N-transformation-based proton production can be used as an indicator of watershed outflow quality in the acid-sensitive ecosystems.     

Comparison of Zostera marina and maerl community metabolism

The photosynthetic and repiratory metabolism of Zostera marina and maerl communities was compared, in the same area of the Bay of Brest in March–April, using benthic chambers. P–E curves for both oxygen and carbon were established for bottom irradiances between 0 and 525 μmol m⁻² s⁻¹. An exponential function was fitted to calculate daily production. Community metabolic quotients did not differ for maerl and seagrass beds. Community photosynthetic quotients were significantly higher (1.19) whereas community respiratory quotients were lower (0.70) than 1. Maerl and seagrass bed P–E curves mainly differed by the minimum saturating irradiance (E_k). Net community production was estimated to 26.8 mmol C m⁻² d⁻¹ for Z. marina meadows and 8.6 mmol C m⁻² d⁻¹ for maerl beds. The two communities can, therefore, be considered as autotrophic during the March–April period. Community respiration did not differ between Z. marina meadows and maerl beds, with an average value of 53.8 mmol C m⁻² d⁻¹ during a day. In similar environmental conditions, the production of maerl beds corresponds to approximately one third that of seagrass meadows. The maerl communities, therefore, form productive ecosystems, relevant to temperate coastal ecosystems functioning.     

Salt marsh colonization by a rocky shore invader: Balanus glandula Darwin (1854) spreads along the Patagonian coast

Balanus glandula, an east Pacific acorn barnacle from rocky shores, was introduced to Mar del Plata, Argentina more than 40 years ago and has spread over 17 latitudinal degrees southward. Here we report the first record of this species living in a soft-bottom environment colonizing the salt marsh plant species Limonium brasiliense, Spartina densiflora, S. alterniflora and Sarcocornia perennis. In addition, we describe the size frequency distribution, density and spatial distribution of the barnacles colonizing the different plant species. The size frequency distribution of Balanus showed a bimodal pattern in all plants. Barnacles were mostly large in S. densiflora, but small in S. alterniflora, with more balanced distributions of small and large barnacles on S. perennis and L. brasiliense. The highest density of barnacles was observed on S. perennis (x = 35.8 ind/cm², SD = 40.5) and S. alterniflora (x = 33.8 ind/cm², SD = 23), while the lowest on L. brasiliense (x = 1.5 ind/cm², SD = 1.18) and S. densiflora (x = 0.17 ind/cm², SD = 0.09). More than 90% of the barnacles on any given plant were found living. While barnacles colonized only the first few centimeters above the soil surface level in S. alterniflora and L. brasiliense, they reached their highest point on S. perennis. The finding of a rocky shore species successfully colonizing soft-bottom marshes within an invaded region brings new perspectives to discussions in biological invasion ecology, and raises additional considerations for coastal environmental management.     

Growth, secondary production and gonad development of two co-existing amphioxus species (Branchiostoma belcheri and B. malayanum) in subtropical Hong Kong

The present study investigated the growth, secondary production and gonad development of two co-existing amphioxus species Branchiostoma belcheri and B. malayanum in subtropical Hong Kong from June 2005 to June 2006. Based on the modal progression analysis, amphioxus populations were decomposed into separate cohorts. The von Bertalanffy growth models were also estimated according to the size incremental data. From the growth models, the size ranges of one, two and three-year-old B. belcheri were estimated to be 5-28 mm, 28-38 mm and 38-45 mm BL, respectively; while the one and two-year-old B. malayanum were estimated to be 7-30 mm and 30-35 mm BL, respectively. The secondary production was calculated at 1.15 g m^− 2 yr^− 1 DW or 0.63 g m^− 2 yr^− 1 AFDW for B. belcheri with density 424 ind m^− 2, and 0.51 g m^− 2 yr^− 1 DW or 0.40 g m^− 2 yr^− 1 AFDW for B. malayanum with density 121 ind m^− 2. The production to biomass ratio (P/B) was 1.13 for B. belcheri and 0.98 for B. malayanum. Changes in the gonad length index indicated that B. belcheri spawned mainly in June and July, while B. malayanum mainly in April and August. As compared with B. belcheri, B. malayanum was characterized by rapid growth, shorter life span, early maturity and lower population density. Such differences in population dynamics may allow both species to share a similar habitat and co-exist in subtropical waters of Hong Kong.     

Interannual patterns of the large free-living nematode assemblages in the Mexican Exclusive Economic Zone,NW Gulf of Mexico after the Deepwater Horizon oil spill

The presence and abundance of particular nematode genera in marine sediments are bioindicators of environmental disturbance. They can even reveal the existence of specific toxicants, such as trace-metals and hydrocarbons derived from fossil fuels. We studied this important infaunal component during a three-year monitoring program in Mexico’s Exclusive Economic Zone (EEZ) in the aftermath of a major oil spill in the northern Gulf of Mexico caused by the sinking of the Deepwater Horizon platform (DWH) in April of 2010. A closer look at the nematode composition and density values throughout and after the DWH oil spill revealed considerable changes. Continental shelf and upper slope sediments sampled in the summer of 2010 included 48 genera and a density of 44.45 ind/10 cm⁻². Eight months later in the winter of 2011, there was a critical decrement in genera number (23) and density (25.22 ind/10 cm⁻²). However, in 2012, the nematode community showed signs of recovery: genus diversity was 58 with a density of 91.45 ind/10 cm⁻². Significant differences were recorded between the first and the last sampling periods, driven by a remarkable turn-over in genera composition, and by an increase in density of the genera Sabatieria, Dorylaimopsis, and Cheironchus. Similarly, significant spatial differences between the nematofauna of the inner-middle shelf and the deepest zone (>2000 m) were detected. Correlation analyses confirmed the tolerant behavior of the above genera to Ni and Co, and their proliferation when hydrocarbon compounds presumably derived from the DWH oil spill increased throughout the study. The Maturity Index (MI) estimated for each survey ranged from 2.35 to 2.6. Environmental Quality Status conditions in the summer of 2010 were good while in the winter of 2011 were poor, and moderate towards the winter of 2012. Index of Trophic Diversity (ITD) values for each survey were high: 0.70, 0.68, and 0.74, respectively. A high predominance of feeding guilds 1B and 2B was recorded throughout the study.The estimated Index of Trophic Diversity (ITD) values resulted high (Table 5). These values apparently indicated that the four feeding types were proportionally distributed in the nematode assemblage. This fact was better reflected during the winter of 2012. Nonetheless, these results are not congruent with the high predominance of feeding guilds 1B and 2B observed throughout the study.     

Leaf growth and population dynamics of intertidal Zostera japonica on the western coast of Korea

Leaf production and population dynamics of Zostera japonica were examined at three elevations of an intertidal transect in Seungbongdo Island on the western coast of Korea. Morphometrics, shoot density, biomass, leaf production, reproductive effort and environmental factors were monitored from October 2001 to October 2002. Z. japonica grew well in the lower intertidal zone from 0.2 to 1.0 m above mean chart datum. The upper station (St. 1) exhibited a finer sediment grain size and richer organic content than the middle (St. 2) and lower stations (St. 3). The size of shoots and leaves was significantly greater at St. 1 than at St. 3, whereas the rhizome internodes were longer at St. 3. Despite differences in morphological characteristics among three stations, seagrass biomass and shoot density were not significantly different among study sites. Shoot density, biomass, morphometrics and leaf productivity exhibited clear seasonal variations, which varied along with seasonal changes of water and air temperature. Leaf productivity measured by the clip and reharvest method was highest in September (4.3 g DW m⁻² d⁻¹) and lowest in February (0.2 g DW m⁻² d⁻¹). Reproductive shoots rapidly increased to maximum density along with the high water temperature in July to September. In the intertidal zone, Z. japonica exhibited faster vegetative growth on muddy sand than on sand, probably due to the difference in nutrient supply. The seasonal changes of water and air temperature were considered to play an important role in the seasonal leaf growth of Z. japonica.     

Leaf growth and population dynamics of intertidal Zostera japonica on the western coast of Korea

Leaf production and population dynamics of Zostera japonica were examined at three elevations of an intertidal transect in Seungbongdo Island on the western coast of Korea. Morphometrics, shoot density, biomass, leaf production, reproductive effort and environmental factors were monitored from October 2001 to October 2002. Z. japonica grew well in the lower intertidal zone from 0.2 to 1.0 m above mean chart datum. The upper station (St. 1) exhibited a finer sediment grain size and richer organic content than the middle (St. 2) and lower stations (St. 3). The size of shoots and leaves was significantly greater at St. 1 than at St. 3, whereas the rhizome internodes were longer at St. 3. Despite differences in morphological characteristics among three stations, seagrass biomass and shoot density were not significantly different among study sites. Shoot density, biomass, morphometrics and leaf productivity exhibited clear seasonal variations, which varied along with seasonal changes of water and air temperature. Leaf productivity measured by the clip and reharvest method was highest in September (4.3 g DW m⁻² d⁻¹) and lowest in February (0.2 g DW m⁻² d⁻¹). Reproductive shoots rapidly increased to maximum density along with the high water temperature in July to September. In the intertidal zone, Z. japonica exhibited faster vegetative growth on muddy sand than on sand, probably due to the difference in nutrient supply. The seasonal changes of water and air temperature were considered to play an important role in the seasonal leaf growth of Z. japonica.     

Growth limitation of Lemna minor due to high plant density

The effect of high population densities on the growth rate of Lemna minor (L.) was studied under laboratory conditions at 23 °C in a medium with sufficient nutrients. At high population densities, we found a non-linear decreasing growth rate with increasing L. minor density. Above a L. minor biomass of ca. 180 g dry weight (DW) m⁻², the net growth rate became negative. At a density of 9 g DW m⁻², a maximum relative growth rate of ca. 0.3 d⁻¹ was found. At very low densities (<9 g m⁻²), we observed an inverse density dependence (or Allee effect). Probably, this lower growth rate was due to lower local temperatures within such partly covered L. minor decks. On the basis of these experimental results and literature data, a simple model was created. To test the model, the density of duckweed in three different Dutch ditches was monitored for 9 weeks in spring. Within this period, full coverage of the ditches by duckweed was reached. The maximum density increased with rising air temperature. The model described the field data well, suggesting that crowding is an important factor in limitation of duckweed growth.     

Comparison of snail density,standing stock,and body size between Caribbean karst wetlands and other freshwater ecosystems

Synthesizing data from multiple studies generates hypotheses about factors that affect the distribution and abundance of species among ecosystems. Snails are dominant herbivores in many freshwater ecosystems, but there is no comprehensive review of snail density, standing stock, or body size among freshwater ecosystems. We compile data on snail density and standing stock, estimate body size with their quotient, and discuss the major pattern that emerges. We report data from 215 freshwater ecosystems taken from 88 studies that we placed into nine categories. Sixty-five studies reported density, seven reported standing stock, and 16 reported both. Despite the breadth of studies, spatial and temporal sampling scales were limited. Researchers used 25 different sampling devices ranging in area from 0.0015 to 2.5 m². Most ecosystem categories had similar snail densities, standing stocks, and body sizes suggesting snails shared a similar function among ecosystems. Caribbean karst wetlands were a striking exception with much lower density and standing stock, but large body size. Disparity in body size results from the presence of ampullariids in Caribbean karst wetlands suggesting that biogeography affects the distribution of taxa, and in this case size, among aquatic ecosystems. We propose that resource quality explains the disparity in density and standing stock between Caribbean karst wetlands and other categories. Periphyton in Caribbean karst wetlands has high carbon-to-phosphorous ratios and defensive characteristics that inhibit grazers. Unlike many freshwater ecosystems where snails are key grazers, we hypothesize that a microbial loop captures much of the primary production in Caribbean karst wetlands.     

Assessment of Lemna gibba L. (duckweed) as a potential ecological indicator for contaminated aquatic ecosystem by boron mine effluent

Duckweeds, as a group, are important early warning indicators for the assessment of contaminated ecosystems due to their propensity to accumulate pollutants. In the present study, we investigated the potential use of Lemna gibba L. (Lemnaceae) as an ecological indicator for boron (B) mine effluent containing B concentration above 10 mg l⁻¹. For this purpose, L. gibba fronds were grown for 7 days in simulated water contaminated with B mine effluent. The important note is that this study was carried out in Kırka (Eskişehir, Turkey) B reserve area, which is the largest borax reserve in all over the world, under natural climatic conditions in the field. The results demonstrated that accumulations of B by L. gibba gradually increased based on the initial B concentrations (10, 25, 50, 100, and 150 mg l⁻¹) of the mine effluent. B concentration in the dry weight of the plant reached 639 mg kg⁻¹ when the minimum initial dosage (10 mg l⁻¹) was applied and 2711 mg kg⁻¹ when the maximum initial dosage (150 mg l⁻¹) was applied during the study. However, significant reductions in their relative growth rates occurred in 50, 100 and 150 mg l⁻¹ initial B concentrations. Results suggest that 25 mg l⁻¹ B concentration in water seemed to be a sensitive endpoint for L. gibba that could be used as a critical bioindicator level of B contaminated water. Following our data, we also constructed a simple growth model under the climatic conditions in this region of Turkey, but in instructive as a worldwide model. L. gibba is, therefore, suggested to be able to use as both an indicator and a phytoremediation tool because of its high accumulation capacity for B contaminated water.     

An annual cycle of biomass and productivity of Vallisneria americana in a subtropical spring-fed estuary

An annual cycle of biomass and productivity of wild celery (Vallisneria americana) was studied in Kings Bay, FL, USA. In situ growth rates were measured monthly between March 2001 and June 2002 in high-density stands, using a modified hole-punching technique, and applied to shoot density data to obtain areal estimates of production. Mean shoot density varied greatly over the study period, ranging between 200 and 800 shoots m⁻². Mean total biomass ranged between 162 and 1013 g m⁻², with aboveground material comprising, on average, 70% of total biomass. Total annual estimated production of new attached shoots was 519 g m⁻². Leaf growth rates peaked at >50 mg shoot⁻¹ d⁻¹, and mass-specific leaf growth ranged 0.6–1.8% d⁻¹. Annually, individual shoots produced 7.4 g of leaf material and completely replaced standing leaf biomass 3.5 times. Areal leaf production was highest in late spring/summer of 2001, and ranged between 3.6 and 23.0 g m⁻² d⁻¹. Annual total leaf production was 2704 g m⁻². Seasonality was not apparent in most variables monitored monthly; only 1 of the 64 relationships we examined between environmental variables (nutrients, chlorophyll a, and irradiance) and Vallisneria biological variables were significant, with relative growth rate increasing linearly with irradiance. Peak biomass and productivity of Vallisneria in Kings Bay were high compared to literature values for other Vallisneria populations as well as global averages for well-studied seagrasses, emphasizing the potential importance of Vallisneria to whole ecosystem functioning in springs, lakes, and oligohaline reaches of many estuaries.     

Assessing reproductive biology of Macrobrachium lamarrei in the Ganges River (NW Bangladesh) in relation to environmental parameters

Macrobrachium lamarrei (H. Milne-Edwards, 1837) is a well-known freshwater prawn species of Bangladesh. The aim of the research is to explore various reproductive aspects (size at sexual maturity, reproductive period and fecundity) of M. lamarrei in the Ganges River, Bangladesh through October 2012 to September 2013. We also study the environmental parameters and their impact on reproduction of M. lamarrei. A total 391 (ovigerous = 141, non-ovigerous = 250) female specimens were collected using Drag net. The TL₅₀ (the TL at which 50% of individuals become mature) was calculated by a logistic equation as 5.20 cm. Based on the availability of ovigerous females the spawning season was February-November with the peak June-July. Further, 50% and 90% ovigerous females were observed when Fulton’s condition factor (K_F) was 0.85 and 1.03, respectively. The total fecundity (F_T) was ranged from 65 to 370 where TL was 4.20–6.40 cm and BW was 0.84–2.50 g. Fecundity was found to be highly correlated with TL (r² ≥ 0.96, r_s = 0.96, p < 0.0001) and BW (r² ≥ 0.88, r_s = 0.93, p < 0.0001). Temperature (r_p = 0.82, p = 0.009), dissolved oxygen (DO) (r_p = −0.83, p = 0.0007), pH (r_p = 0.80, p = 0.0014) and total alkalinity (r_p = −0.87, p = 0.0002), were highly correlated with ovigerous females. The average temperature on peak spawning season was 32 °C. Also, the spawning period connected with the peak rainfall and showed a notable relation between rainfall and ovigerous females. In addition, exploration of long data series pointed that yearly average air temperature is rising by 0.029 °C yr⁻¹, whereas yearly average rainfall is falling by 2.96 mm yr⁻¹. Therefore, the result will be helpful for the sustainable management and conservation of M. lamarrei through fixed permissible mesh size and establishment of a ban period in the Ganges River, Bangladesh and adjoining ecosystems.     

Comparison of two matrices for selective recovery of C595 diabody fragment (dbFv) from Escherichia coli lysates

A comparative study of the performance of two types of adsorbent (Streamline Quartz Base and Upfront Matrices), derivatized with the same affinity ligand (RPAP) to recover C595 diabody fragment (dbFv) from Escherichia coli lysates has been undertaken. Both streamline and Upfront Matrices are characterized by a particle size range of 100–300 μm. Streamline has a density of 1.20 g cm⁻³ and ligand concentration of 0.85 μmol ml⁻¹. Upfront has a density of 1.35 g cm⁻³ and ligand concentration of 0.83 μmol ml⁻¹. The release of C595 dbFv from E. coli cells was achieved by a chemical lysis method. The recovery performance of both adsorbents was evaluated in terms of operational productivity and elution yield of C595 dbFv in packed bed (clarified feedstock) and expanded bed (unclarified and clarified feedstock) chromatography systems. Streamline and Upfront adsorbents exhibited diabody operational productivities of 131 and 202 mg l⁻¹, respectively, with an elution yield of 92 and 94%, respectively, in packed bed operation. Streamline and Upfront adsorbents exhibited diabody operational productivities of 54.5 and 123.7 mg l⁻¹, respectively, with an elution yield of 89 and 92%, respectively, in expanded bed operation.