Harmful algal blooms in coastal waters: options for prevention, control and mitigation

This report is the product of a panel of experts in the science of blooms of unicellular marine algae which can cause mass mortalities in a variety of marine organisms and cause illness and even death in humans who consume contaminated seafood. These phenomena are collectively termed harmful algal blooms or HABs for short. As a counterpart to recent assessments of the priorities for scientific research to understand the causes and behavior of HABs, this assessment addressed the management options for reducing their incidence and extent (prevention), actions that can quell or contain blooms (control), and steps to reduce the losses of resources or economic values and minimize human health risks (mitigation). This assessment is limited to an appraisal of scientific understanding, but also reflects consideration of information and perspectives provided by regional experts, agency managers and user constituencies during three regional meetings. The panel convened these meetings during the latter half of 1996 to solicit information and opinions from scientific experts, agency managers and user constituencies in Texas, Washington, and Florida. The panel's assessment limited its attention to those HABs that result in neurotoxic shellfish poisoning, paralytic shellfish poisoning, brown tides, amnesic shellfish poisoning, and aquaculture fish kills. This covers most, but certainly not all, HAB problems in the U.S.

Development, validation, and utilization of a competitive enzyme-linked immunosorbent assay for the detection of antibodies against Brucella species in marine mammals

A competitive enzyme-linked immunosorbent assay (cELISA) was developed by using a whole-cell antigen from a marine Brucella sp. isolated from a harbor seal (Phoca vitulina). The assay was designed to screen sera from multiple marine mammal species for the presence of antibodies against marine-origin Brucella. Based on comparisons with culture-confirmed cases, specificity and sensitivity for cetacean samples tested were 73% and 100%, respectively. For pinniped samples, specificity and sensitivity values were 77% and 67%, respectively. Hawaiian monk seal (Monachus schauinslandi; n = 28) and bottlenose dolphin (Tursiops truncatus; n = 48) serum samples were tested, and the results were compared with several other assays designed to detect Brucella abortus antibodies. The comparison testing revealed the marine-origin cELISA to be more sensitive than the B. abortus tests by the detection of additional positive serum samples. The newly developed cELISA is an effective serologic method for detection of the presence of antibodies against marine-origin Brucella sp. in marine mammals.

Estimation of bycatch in shrimp trawl fisheries: a comparison of estimation methods using field data and simulated data

Bycatch, or the incidental catch of nontarget organisms during fi shing operations, is a major issue in U.S. shrimp trawl fisheries. Because bycatch is typically discarded at sea, total bycatch is usually estimated by extrapolating from an observed bycatch sample to the entire fleet with either mean-per-unit or ratio estimators. Using both field observations of commercial shrimp trawlers and computer simulations, I compared five methods for generating bycatch estimates that were used in past studies, a mean-per-unit estimator and four forms of the ratio estimator, respectively: 1) the mean fish catch per unit of effort, where unit effort was a proxy for sample size, 2) the mean of the individual fish to shrimp ratios, 3) the ratio of mean fish catch to mean shrimp catch, 4) the mean of the ratios of fish catch per time fished (a variable measure of effort), and 5) the ratio of mean fish catch per mean time fished. For field data, different methods used to estimate bycatch of Atlantic croaker, spot, and weakfish yielded extremely different results, with no discernible pattern in the estimates by method, geographic region, or species. Simulated fishing fleets were used to compare bycatch estimated by the fi ve methods with “actual” (simulated) bycatch. Simulations were conducted by using both normal and delta lognormal distributions of fish and shrimp and employed a range of values for several parameters, including mean catches of fish and shrimp, variability in the catches of fish and shrimp, variability in fishing effort, number of observations, and correlations between fish and shrimp catches. Results indicated that only the mean per unit estimators provided statistically unbiased estimates, while all other methods overestimated bycatch. The mean of the individual fish to shrimp ratios, the method used in the South Atlantic Bight before the 1990s, gave the most biased estimates. Because of the statistically significant two- and 3-way interactions among parameters, it is unlikely that estimates generated by one method can be converted or corrected to estimates made by another method: therefore bycatch estimates obtained with different methods should not be compared directly.

Efficiency of bycatch reduction devices in small otter trawls used in the Florida shrimp fishery

Two bycatch reduction devices (BRDs)—the extended mesh funnel (EMF) and the Florida fisheye (FFE)—were evaluated in otter trawls with net mouth circumferences of 14 m, 17 m, and 20 m and total net areas of 45 m2. Each test net was towed 20 times in parallel with a control net that had the same dimensions and configuration but no BRD. Both BRDs were tested at night during fall 1996 and winter 1997 in Tampa Bay, Florida. Usually, the bycatch was composed principally of finfish (44 species were captured); horseshoe crabs and blue crabs seasonally predominated in some trawls. Ten finfish species composed 92% of the total finfish catch; commercially or recreationally valuable species accounted for 7% of the catch. Mean finfish size in the BRD-equipped nets was usually slightly smaller than that in the control nets. Compared with the corresponding control nets, both biomass and number of finfish were almost always less in the BRD-equipped nets but neither shrimp number nor biomass were significantly reduced. The differences in proportions of both shrimp and finfish catch between the BRD-equipped and control nets varied between seasons and among net sizes, and differences in finfish catch were specific for each BRD type and season. In winter, shrimp catch was highest and size range of shrimp was greater than in fall. Season-specific differences in shrimp catch among the BRD types occurred only in the 14-m, EMF nets. Finfish bycatch species composition was also highly seasonal; each species was captured mainly during only one season. However, regardless of the finfish composition, the shrimp catch was relatively constant. In part as a result of this study, the State of Florida now requires the use of BRDs in state waters.

Game Vertebrate Densities in Hunted and Nonhunted Forest Sites in Manu National Park, Peru

Manu National Park of southern Peru is one of the most renowned protected areas in the world, yet large-bodied vertebrate surveys conducted to date have been restricted to Cocha Cashu Biological Station, a research station covering <0.06 percent of the 1.7Mha park. Manu Park is occupied by >460 settled Matsigenka Amerindians, 300-400 isolated Matsigenka, and several, little-known groups of isolated hunter-gatherers, yet the impact of these native Amazonians on game vertebrate populations within the park remains poorly understood. On the basis of 1495 km of standardized line-transect censuses, we present density and biomass estimates for 23 mammal, bird, and reptile species for seven lowland and upland forest sites in Manu Park, including Cocha Cashu. We compare these estimates between hunted and nonhunted sites within Manu Park, and with other Neotropical forest sites. Manu Park safeguards some of the most species-rich and highest biomass assemblages of arboreal and terrestrial mammals ever recorded in Neotropical forests, most likely because of its direct Andean influence and high levels of soil fertility. Relative to Barro Colorado Island, seed predators and arboreal folivores in Manu are rare, and generalist frugivores specializing on mature fruit pulp are abundant. The impact of such a qualitative shift in the vertebrate community on the dynamics of plant regeneration, and therefore, on our understanding of tropical plant ecology, must be profound. Despite a number of external threats, Manu Park continues to serve as a baseline against which other Neotropical forests can be gauged.

Consumption of fa cai Nostoc soup: A Potential for BMAA exposure from Nostoc cyanobacteria in China?

Grown in arid regions of western China the cyanobacterium Nostoc flagelliforme - called fa cai in Mandarin and fat choy in Cantonese - is wild-harvested and used to make soup consumed during New Year's celebrations. High prices, up to $125 USD/kg, led to overharvesting in Inner Mongolia, Ningxia, Gansu, Qinghai, and Xinjiang. Degradation of arid ecosystems, desertification, and conflicts between Nostoc harvesters and Mongol herdsman concerned the Chinese environmental authorities, leading to a government ban of Nostoc commerce. This ban stimulated increased marketing of a substitute made from starch. We analysed samples purchased throughout China as well as in Chinese markets in the United States and the United Kingdom. Some were counterfeits consisting of dyed starch noodles. A few samples from California contained Nostoc flagelliforme but were adulterated with starch noodles. Other samples, including those from the United Kingdom, consisted of pure Nostoc flagelliforme. A recent survey of markets in Cheng Du showed no real Nostoc flagelliforme to be marketed. Real and artificial fa cai differ in the presence of beta-N-methylamino-L-alanine (BMAA). Given its status as a high-priced luxury food, the government ban on collection and marketing, and the replacement of real fa cai with starch substitutes consumed only on special occasions, it is anticipated that dietary exposure to BMAA from fa cai will be reduced in the future in China.

茂金属线性低密度聚乙烯的光氧化和热力学降解研究

聚乙烯是广泛应用的合成高分子材料之一，工业化己有几十年历史，为适应不断扩展的加工及应用的要求，氧化降解反应一直是较活跃的研究领域。目前为止，一些氧化降解的规律和机理已经确定，某些还在积极地研究探索之中。茂金属线性低密度聚乙烯（m-LLDPE）是进入九十年代以后才出现的采用新型茂金属催化剂催化合成的树脂，与传统 Ziegler-Natta线性低密度聚乙烯（LLDPE）相比，其具有分子量分布窄，共聚单体在主链中分布均匀的特点，决定了它具有比传统LLDPE更加优异的使用性能，因而在生产生活中得到广泛应用。目前对其氧化降解的研究较少，因此对m-LLDPE的氧化及稳定性的研究对指导其应用有着积极的意义。本论文选择催化剂和共聚单体类型不同的三种m-LLDPE和两种传统LLDPE对比研究了m-LLDPE的光氧化和热力学降解稳定性，而且研究了过渡金属化合物光敏化剂对它的热力学降解的影响，热力学降解和光敏化剂对m-LLDPE的光、热氧化稳定性的影响。化测试方法表征m-LLDPE的光氧俐反应，长时间光氧化后支化度和结晶度都有不同程度的上升，光氧化速率主要受亚乙烯基双链浓度的影响，受支化度的影响不明显。因此在合成m-LLDPE的过程中应该合理设计茂金属催化剂，降低聚合产品中亚乙烯基双键的浓度，提高它的光氧化稳定性。采用熔体流动速率、流变法和红外光谱法研究了m-LLDPE和传统LLDPE在密炼过程中的热力学降解反应，和光敏化剂对热力学降解反应的影响，利用氧化诱导温度法快速表征热力学降解对m-LLDPE和LLDPE的氧化稳定性的影响，并利用自然光曝晒测试碳基指数和力学性能的变化和热氧化观察脆化时间的方法研究了热力学降解对它们的光、热氧化稳定性的影响，为m-LLDPE在气候条件下应用提供理论依据。共聚单体类型相同的m-LLDPEI和m-LLDPEZ相比较，m-LLDPEI在热力学降解过程中生成更多的氧化产物，光敏化剂硬脂酸钻和乙酰基丙酮钻对m-LLDPEI热力学降解生成氧化产物的敏化作用更强，也更显著地降低了密炼后样品的氧化诱导温度。流变法不仅表征了m-LLDPEI热力学降解过程中的分子结构的变化，也反映了样品的热稳定性。共聚单体类型不同的m-LLDPE3和LLDPEZ相比较，热力学降解后熔体流动速率下降得多，但拨基指数上升较少，这是m-LLDPE3密炼过程中熔融粘度较高的原因。光敏化剂更强烈得增强了LLDPE2的热力学降解过程中氧化产物的形成。热力学降解明显的降低了 LLDPE2的光氧化稳定性而没有对m-LLDPE3的光氧化稳定性产生明显作用，同时敏化剂对LLDPE2的光氧化敏化作用也更强烈一些。本文还研究了光敏化剂硬脂酸钻和硬脂酸铁对三种共聚单体类型不同的传统LLDPE和LDPE的光敏化效果，发现光敏化剂对不同链结构的聚乙烯的光敏化效果存在很大的差异，光敏化作用的顺序为：乙烯一辛烯共聚LLDPE＜乙烯一丁烯共聚LLDPE＜LDPE，光敏化效果并不随敏化剂浓度的增大而增强。从红外光谱可以分析聚乙烯中亚乙烯基浓度越高，光照过程中形成的氢过氧化物浓度越高，光敏化剂的敏化效果越强。

Nd(OR)_(3-m)Cl_m-AlEt_3二元催化体系对共轭双烯的聚合以及微观结构和诱导效应指数的关系

本文首先对过渡金属（十一区和d-区）烷氧基型Ziegler-Natta催化剂的研究作了简单回顾。在此基础上，合成了迄今未见报导的Nd(OR)_(3-m)Cl_m-AlEt_3二元催化体系，并通过一系列的基本实验，从多方面考查了该催化体系对共轭双烯的聚合规律以及所得聚合物的微观结构。基于这此研究。进而发现了聚共轭双烯的微观结构和Ziegler-Natta催化剂中卤素-过渡金属键上电子对的偏移程度有关，如果以“诱导效应指数”（它是只和催化剂结构以及构成该催化剂的原子的电负性及共价半径有关的常数）来表示这种电子对的偏移，则微观结构和诱导效应指数成线性关系。对文献数据的处理，进一步地证实了这一结论。