With the aim of investigating the effects of carbonaceous sorbent amendment on plant health and end point contaminant bioavailability, plant experiments were set up to grow maize (Zea mays) in soil contaminated with polycyclic aromatic hydrocarbons (PAHs) and metals. Maize and pine derived biochars, as well as a commercial grade activated carbon, were used as amendments. Plant growth characteristics, such as chlorophyll content and shoot to root biomass, improved with sorbent amendment to varying extents and contaminant uptake to shoots was consistently reduced in amended soils. By further defining the conditions in which sorbent amended soils successfully reduce contaminant bioavailability and improve plant growth, this work will inform field scale remediation efforts.

To assess the effects of leaf age/layer on the response of photosynthesis to chronic ozone (O3), Cyclobalanopsis glauca seedlings, a dominant evergreen broadleaf tree species in sub-tropical regions, were exposed to either ambient air (AA) or elevated O3 (AA + 60 ppb O3, E-O3) for two growing seasons in open-top chambers. Chlorophyll content, gas exchange and chlorophyll a fluorescence were investigated three times throughout the 2nd year of O3 exposure. Results indicated that E-O3 decreased photosynthetic parameters, particularly light-saturated photosynthesis rate, stomatal conductance and effective quantum yield of PSII photochemistry of current-year leaves but not previous-year leaves. Stomatal conductance of plants grown under ambient conditions partially contributed to the different response to E-O3 between leaf layers. Light radiation or other physiological and biochemical processes closely related to photosynthesis might play important roles. All suggested that leaf ages or layers should be considered when assessing O3 risk on evergreen woody species.

To examine the influence of habitat alteration by tideflat reclamation on the physiological ecology of Ruditapes philippinarum, seasonal variations in its condition, gross biochemical composition, and reproductive cycle were compared for a yearly cycle between a reclaimed flat (Gomsohang, GS) and a natural flat (Hajun, HJ) in Gomso Bay, Korea. Concentrations of chlorophyll a and seston (as well as its energy value as food available to the clam) were consistently higher at HJ than at GS. Condition, dry tissue weight, and energy reserves (proteins and carbohydrates) of the clams were much higher at HJ than at GS during spring–summer, when fast growth and gametogenic development occur. Furthermore, their spring gametogenic development and spawning were advanced at HJ compared with GS. Our results suggest that the Manila clam encounters nutritionally stressful environmental conditions in altered habitats after tideflat reclamation that lead to lowered nutrient accumulation and a changing reproductive cycle.

Effects of fish culture can alter the adjacent ecosystems. This study compared seagrass species compositions in 2012 with those in 1995, when fish culture was less intensive compared to 2012 in the region. Observations were conducted at the same four sites around Santiago Island, Bolinao: (1) Silaqui Island, (2) Binaballian Loob, (3) Pislatan and (4) Santa Barbara, and by using the same methods as those of Bach et al. (1998). These sites were originally selected along a siltation gradient, ranging from Site 1, the most pristine, to Site 4, a heavily silted site. By 2012, fish culture had expanded around Sites 2, 3 and 4, where chlorophyll a (Chl a) was greater in 2012 than in 1995 by one order of magnitude. Enhalus acoroides and Cymodocea serrulata, which were recorded in 1995, were no longer present at Site 4, where both siltation and nutrient load are heavy.

A multispecies bloom caused by the centric diatoms, viz. Coscinodiscus radiatus, Chaetoceros lorenzianus and the pennate diatom Thalassiothrix frauenfeldii was investigated in the context of its impact on phytoplankton and microzooplankton (the loricate ciliate tintinnids) in the coastal regions of Sagar Island, the western part of Sundarban mangrove wetland, India. Both number (15–18 species) and cell densities (12.3×103cellsl−1 to 11.4×105cellsl−1) of phytoplankton species increased during peak bloom phase, exhibiting moderately high species diversity (H′=2.86), richness (R′=6.38) and evenness (E′=0.80). The diatom bloom, which existed for a week, had a negative impact on the tintinnid community in terms of drastic changes in species diversity index (1.09–0.004) and population density (582.5×103 to 50×103indm−3). The bloom is suggested to have been driven by the aquaculture activities and river effluents resulting high nutrient concentrations in this region. An attempt has been made to correlate the satellite remote sensing-derived information to the bloom conditions. MODIS-Aqua derived chlorophyll maps have been interpreted.

The partitioning and bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in water, suspended particulate matter (SPM), and fish samples from the Dongjiang River (DR), Pearl River (PR), and the Pearl River Estuary (PRE) were examined. Although PAHs are much lower in PRE than in DR or PR, PAHs in some fish species are significantly higher in PRE than in DR or PR. Aqueous or particulate PAHs respectively show significant correlations with dissolved organic carbon, particulate organic matter, and chlorophyll a, suggesting that biological pumping effect regulates their distribution. The in situ partitioning coefficients (logKoc) for PAHs are one order magnitude higher than the empirical logKoc–logKow correlation. The bioconcentration factor (BCF) is slightly higher for the marine fish than for the freshwater fish. The above phenomena indicate that BCF may vary due to the diversity of fish species, feeding habits, and metabolism of PAHs in fish.

Ocean-color remote sensing has been used as a tool to detect phytoplankton size classes (PSCs). In this study, a three-component model of PSC was reparameterized using seven years of pigment measurements acquired in the South China Sea (SCS). The model was then used to infer PSC in a cyclonic eddy which was observed west of Luzon Island from SeaWiFS chlorophyll-a (chla) and sea-surface height anomaly (SSHA) products. Enhanced productivity and a shift in the PSC were observed, which were likely due to upwelling of nutrient-rich water into the euphotic zone. The supply of nutrients promoted the growth of larger cells (micro- and nanoplankton), and the PSC shifted to greater sizes. However, the picoplankton were still important and contributed ∼48% to total chla concentration. In addition, PSC time series revealed a lag period of about three weeks between maximum eddy intensity and maximum chlorophyll, which may have been related to phytoplankton growth rate and duration of eddy intensity.

Alkaline phosphatase (AP) activity was studied on homogenates of particulate material in relation to the concentrations of AP-hydrolysable (DOPpa) and AP-non hydrolysable (DOPr) phosphorus. AP activity had high and low Km components. The high affinity activity came from ectoenzymes. It was negatively and significantly correlated with DOPr as with the sum of DIP and DOPr, but not with DOPpa. However negative correlations with DOPpa existed when DIP concentrations decreased. Significant correlations with the sum of DIP and DOPpa attest of additive effects of DIP and DOPpa. The low affinity activity came from “endoenzymes”. This activity was also negatively correlated with DOP (DOPpa and DOPr). DOPpa and to a lesser extent DOPr influenced also positively the protein and/or Chlorophyll biomasses of the particulate material. We hypothesize that the correlations of the AP activity with DOP come from regenerated phosphate sequestered in cells and not released in the environment with DIP.

Seagrasses around the world are threatened by human activities that degrade water quality and reduce light availability. In this study, light requirements were determined for four common and abundant seagrasses along the Gulf coast of peninsular Florida using a threshold detecting algorithm. Light requirements ranged from 8% to 10% of surface irradiance for Halophila engelmannii to 25–27% of surface irradiance for Halodule wrightii. Requirements for all species differed from previous reports generated at other locations. Variations were attributed to morphological and physiological differences, as well as adaptation to light histories at specific locations. In addition, seagrasses were absent from stations with significantly higher concentrations of total nitrogen, total phosphorus, chlorophyll a and color. These results confirm the need to address links between increased anthropogenic nutrient loads, eutrophication, reduced light penetration, and loss of seagrasses and the services they provide.

In this study, the influence of sediments deposited on the leaves of different mangrove species due to tidal movements on photosynthetic characteristics and chlorophyll fluorescence of the species was explored. The degree of accelerated degradation among different mangrove species was also obtained. Results show that the leaves of mangrove species have varying degrees of sediment deposition. Sediment deposition leads to photosynthetic reduction and physiological stress among Kandelia candel, Aegiceras corniculatum, and Avicennia marina in the Quanzhou Bay. Thus, the deposition of suspended sediments from tidal currents is an important environmental factor that accelerates the degradation of some mangrove species.