Great Lakes Cladophora in the 21st century: same algae—different ecosystem

Nuisance growth of the attached, green alga Cladophora was considered to have been abated by phosphorus management programs mandated under the Great Lakes Water Quality Agreement. The apparent resurgence of nuisance growth in Lakes Erie, Michigan and Ontario has been linked conceptually to ecosystem alterations engineered by invasive dreissenid mussels (Dreissena polymorpha and Dreissenabugensis). Here, we apply contemporary modeling tools and historical water quality data sets in quantifying the impact of long-term changes in phosphorus loading and dreissenid-mediated changes in water clarity on the distribution and production of Cladophora. It is concluded that reductions in phosphorus loading in the pre-dreissenid period achieved the desired effect, as model simulations were consistent with the biomass declines reported from the early 1970s to the early 1980s. These declines were, however, largely offset by dreissenid-driven changes in water clarity that extended the depth of colonization by Cladophora, increasing total production. We were not able to isolate and quantify the significance of dreissenid mediation of phosphorus cycling using the historical database. Phosphorus management remains the appropriate mechanism for reducing nuisance levels of Cladophora growth. The development of action plans will require an improved understanding of nearshore phosphorus dynamics such as might be obtained through regular monitoring of soluble reactive phosphorus levels, internal phosphorus content and Cladophora biomass in impacted nearshore regions of the Great Lakes.     

News & notes.

Presents a series of noteworthy items regarding and relevant to Division 26 (History of Psychology). The items include: President's Letter; Report from the American Psychological Association Council Representative; Proposed Bylaws Amendment; Presidential Candidates' Statements; 2003 Convention Program; Personal News; Notice of Deaths; APA Archives Activities for 2002; and History of Psychology Around the World. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

News & notes.

This article covers the latest information about the The Society for the History of Psychology. The news and notes summarize the call for fellowship nominations and papers for the 2006 convention. The column also discusses membership, personal news, and meetings and exhibits concerning the history of psychology around the world. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

News & notes.

Presents a series of noteworthy items regarding and relevant to Division 26 (History of Psychology). These items include: Call for Program Proposals for 2004 Convention; Call for Fellows Nominations; Supporting Division 26; Notice of Deaths; Personal News; History of Psychology Around the World; and a Call for Papers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantitative analysis of plasma acylcarnitines using gas chromatography chemical ionization mass fragmentography

A stable isotope dilution gas chromatography chemical ionization mass spectrometry (GC-CI-MS) method was developed for the quantitative profiling of plasma acylcarnitines. The clean-up procedure was comprised of a solid-phase cation exchange extraction using PRS-columns from which the acylcarnitines were eluted with a barium chloride solution. Isolated acylcarnitines were transformed into acyloxylactones and analyzed by positive GC-CI-MS using isobutane as reactant gas. The selected monitoring of a common ion at m/z [85]+ and the protonated molecular ion enabled a selective and sensitive detection of all C2-C18 acylcarnitines. An accurate quantitation was achieved by the use of stable isotope-labeled internal standards (C2-C18) and acylcarnitines could be analyzed in the sub-nanomolar range. Control values for C2-C18 acylcarnitines in plasma were established. Concentrations ranged from 0.02 micromol/L for C14-acylcarnitine to 4.90 micromol/L for C2-acylcarnitine. The diagnostic suitability of the method was demonstrated for patients with medium-chain acyl-CoA dehydrogenase deficiency and very long-chain acyl-CoA dehydrogenase deficiency.     

Posttraumatic stress disorder in adult female survivors of child sexual abuse: A comparison study.

This study compared symptoms of posttraumatic stress disorder (PTSD) in a group of 45 adult women in outpatient treatment for childhood sexual abuse (CSA) and a group of 31 women who reported no CSA. The comparison group consisted of women in outpatient treatment for problems in their committed relationships with male living partners. This research also investigated the traumatic impact of dual abuse (both childhood sexual and physical abuse). Standardized assessment instruments were used to measure PTSD, CSA, and childhood physical abuse (CPA). Results indicated that 86.7% of the CSA group met criteria for current PTSD in accordance with the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised; American Psychiatric Association, 1987), compared with 19.4% of the relationship distress group, providing support for CSA as an etiological agent for PTSD. In addition, 89% of the CSA survivors reported CPA. Multivariate analysis revealed that both CSA and CPA exposure variables accounted for a significant portion of the variance in PTSD symptoms in the CSA group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fate of phosphorus from a point source in the Lake Michigan nearshore zone

Nutrient loading into Lake Michigan can produce algal blooms which in turn can lead to hypoxia, beach closures, clogging of water intakes, and reduced water quality. The Great Lakes Water Quality Agreement targets for Lake Michigan are 5600 MT annually for total phosphorus (TP) loading, 7 μg L^?1 lake-wide mean TP concentration, and a chlorophyll-a concentration of 1.8 μg L^?1. However, in light of the recent resurgence of nuisance algal (Cladophora sp.) growth in the nearshore zone, the validity of these targets is now uncertain. The occurrence and abundance of Cladophora in the nearshore area depends primarily on the availability of dissolved phosphorus, light, and temperature. The availability of dissolved phosphorus is a potentially useful indicator of nearshore areas susceptible to excessive Cladophora growth and impaired water quality. Regulating agencies are looking for guidance in determining phosphorus loading rates that minimize local exceedance of the lake target concentration. In this study, the lake assimilative capacity was quantified by applying a biophysical model to estimate the area required for mixing and diluting wastewater treatment plant outfall TP loadings to the level of the lake target concentration during the Cladophora growing season. Model results compared well with empirical measurements of particulate and dissolved phosphorus as well as Cladophora biomass and phosphorus content. The model was applied to test scenarios of wastewater treatment plant phosphorus loading in two different years, in order to help establish phosphorus discharge limits for the plant.     

Temporal trends of phytoplankton and zooplankton stable isotope composition in tropical Lake Malawi

Stable isotope ratios of three seston size classes (20–100 μm, 2–20 μm, and 0.2–2 μm) and zooplankton species were analyzed to determine the plankton food web structure of Lake Malawi. Over an annual cycle, seston δ¹³C varied between ?20.41‰ and ?27.43‰ with a mean value of ?24.27‰ ± 1.2 while δ¹³C values for zooplankton fluctuated between ?22‰ and ?25‰ with a mean of ?23.84‰ ± 0.77. Seston δ¹³C fluctuations appeared to be related to changes in physical and meteorological conditions in the lake that ultimately control nutrient availability. The highest seston δ¹³C values observed during the rainy and mixed seasons likely result from high phytolankton growth rates. δ¹⁵N of plankton was temporally variable, suggesting short term changes in N cycling dynamics that control the supply of N to phytoplankton. Very low seston δ¹⁵N values recorded during the mixing season suggest excess NO₃^? availability resulting from upwelling and vertical mixing. In contrast to expectations the calanoid Tropodiaptomus cunningtoni appeared to feed at a trophic level higher than that of all other zooplankton species, including the cyclopoid, Mesocyclops aequatorialis aequatorialis. δ¹⁵N values indicate that zooplankton were nearly 2 trophic levels above seston in the early stratified season. This implies that adult zooplankton could be utilizing forms of food other than phytoplankton during this period, such as nauplii or protozoans. This extra step in the food web, and the trophic positions of large zooplankton species, may alter estimates of food web efficiency and potential fish production for Lake Malawi.