Characterization of plankton from the Galveston estuary

The purpose of this report is to summarize the published studies on phytoplankton and zooplankton in the Galveston Estuary. Before this project had begun, it was determined that there was insufficient long term data on plankton in the Galveston Estuary to attempt trend analysis. Information on phytoplankton species diversity, biomass and primary production, along with information on zooplankton species diversity and abundance, is summarized. This information is compared to similar data on other Texas and United States estuaries where available. Recommendations for a long term monitoring program are made. A bibliography of all Galveston Estuary plankton studies and an annotated bibliography of the major studies and publications are available in the GBNEP Information Center.Marine Scienc

Interactions between Zooplankton and Crude Oil: Toxic Effects and Bioaccumulation of Polycyclic Aromatic Hydrocarbons

We conducted ship-, shore- and laboratory-based crude oil exposure experiments to investigate (1) the effects of crude oil (Louisiana light sweet oil) on survival and bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in mesozooplankton communities, (2) the lethal effects of dispersant (Corexit 9500A) and dispersant-treated oil on mesozooplankton, (3) the influence of UVB radiation/sunlight exposure on the toxicity of dispersed crude oil to mesozooplankton, and (4) the role of marine protozoans on the sublethal effects of crude oil and in the bioaccumulation of PAHs in the copepod Acartia tonsa. Mortality of mesozooplankton increased with increasing oil concentration following a sigmoid model with a median lethal concentration of 32.4 ml L21 in 16 h. At the ratio of dispersant to oil commonly used in the treatment of oil spills (i.e. 1:20), dispersant (0.25 ml L21 ) and dispersant- treated oil were 2.3 and 3.4 times more toxic, respectively, than crude oil alone (5 ml L21 ) to mesozooplankton. UVB radiation increased the lethal effects of dispersed crude oil in mesozooplankton communities by 35%. We observed selective bioaccumulation of five PAHs, fluoranthene, phenanthrene, pyrene, chrysene and benzo[b]fluoranthene in both mesozooplankton communities and in the copepod A. tonsa. The presence of the protozoan Oxyrrhis marina reduced sublethal effects of oil on A. tonsa and was related to lower accumulations of PAHs in tissues and fecal pellets, suggesting that protozoa may be important in mitigating the harmful effects of crude oil exposure in copepods and the transfer of PAHs to higher trophic levels. Overall, our results indicate that the negative impact of oil spills on mesozooplankton may be increased by the use of chemical dispersant and UV radiation, but attenuated by crude oil-microbial food webs interactions, and that both mesozooplankton and protozoans may play an important role in fate of PAHs in marine environments.Zoe Wambaugh was supported by the National Science Foundation (NSF) Research Experiences for Undergraduates (REU) program (grant OCE- 1062745). This research was made possible by a grant from BP/The Gulf of Mexico Research Initiative through the University of Texas Marine Science Institute (DROPPS consortium: ‘Dispersion Research on Oil: Physics and Plankton Studies’). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Marine Scienc

Resonance and frequency-locking phenomena in spatially extended phytoplankton-zooplankton system with additive noise and periodic forces

In this paper, we present a spatial version of phytoplankton-zooplankton model that includes some important factors such as external periodic forces, noise, and diffusion processes. The spatially extended phytoplankton-zooplankton system is from the original study by Scheffer [M Scheffer, Fish and nutrients interplay determines algal biomass: a minimal model, Oikos \textbf{62} (1991) 271-282]. Our results show that the spatially extended system exhibit a resonant patterns and frequency-locking phenomena. The system also shows that the noise and the external periodic forces play a constructive role in the Scheffer's model: first, the noise can enhance the oscillation of phytoplankton species' density and format a large clusters in the space when the noise intensity is within certain interval. Second, the external periodic forces can induce 4:1 and 1:1 frequency-locking and spatially homogeneous oscillation phenomena to appear. Finally, the resonant patterns are observed in the system when the spatial noises and external periodic forces are both turned on. Moreover, we found that the 4:1 frequency-locking transform into 1:1 frequency-locking when the noise intensity increased. In addition to elucidating our results outside the domain of Turing instability, we provide further analysis of Turing linear stability with the help of the numerical calculation by using the Maple software. Significantly, oscillations are enhanced in the system when the noise term presents. These results indicate that the oceanic plankton bloom may partly due to interplay between the stochastic factors and external forces instead of deterministic factors. These results also may help us to understand the effects arising from undeniable subject to random fluctuations in oceanic plankton bloom.Comment: Some typos errors are proof, and some strong relate references are adde

Changes in Herbaceous Plant Diversity in an Old-Growth Ohio Forest Before and After Emerald Ash Borer Invasion

The herbaceous layer of eastern North American deciduous forests is an important contributor to biodiversity in this region. One of the greatest threats to herbaceous plant diversity is the introduction of invasive species, which can suppress native species and alter local environmental conditions. Agrilus planipennis (emerald ash borer) is a non-native insect pest that has caused a mass death of ash trees (Fraxinus spp.) in North America since its introduction to the United States. The resultant changes in canopy structure may affect local conditions and thus have indirect impacts on herbaceous layer composition. Drew Woods State Nature Preserve is a 6-ha old-growth forest fragment in Darke County, Ohio that has recently experienced EAB-related ash mortality. Our goal was to understand how herbaceous layer diversity has been changing through time in response to this sitewide canopy disturbance. Annual surveys of herbaceous biodiversity were conducted across 32 1-m2 sampling plots from 2012 to 2017. Species richness, total cover, Shannon Diversity, and species evenness were calculated for each plot by year, and beta diversity (Bray-Curtis Dissimilarity) was used to assess community turnover through time. Repeated measures ANOVA was used to test for significant changes over this period, and regression analyses were used to understand relationships between diversity and environmental variables (canopy cover, soil moisture, and distance to forest edge). Species richness and herbaceous cover tended to be higher in more recent sampling years. There was a temporally consistent north-south gradient where diversity tended to be greater toward the southern edge of the stand. These results suggest that EAB-induced ash mortality is increasing light availability via canopy gap formation, which is a driving factor of herbaceous diversity. The full impact of EAB is not yet clear, but will likely extend beyond ash mortality and have important indirect effects on other parts of forest ecosystems

Recruitment of estuarine dependent species of commercial and recreational importance through the Aransas Ship Channel

Several species of shellfish and finfish of commercial or recreational importance in the Nueces and Mission-Aransas Estuaries possess life history patterns that are dependent upon estuaries, whereby juvenile members of these species live and mature in these estuary “nurseries”, then migrate to the Gulf of Mexico as reproductive adults, releasing their eggs and planktonic larvae in the open ocean. The larvae feed, grow and develop in the Gulf of Mexico, but must return back to these estuaries to complete their life cycle. These planktonic larvae possess weak swimming skills and are too small to migrate directly back into the estuaries under their own power, so they must depend on hydrodynamic and environmental signals to selectively ride tidal and meteorologically driven currents back into the estuaries and avoid being flushed back out when these currents reverse. Tides are relatively small in the Northwestern Gulf of Mexico, and especially for estuaries in South Texas with little inflow of freshwater, meteorological forcing over times scales of several days play a significant role in estuarine-shelf water exchanges (Smith 1978). The Aransas Pass connecting the Nueces and Mission-Aransas Estuaries to the Gulf of Mexico was originally a shallow inlet between Mustang and San Jose Islands and it has been dredged to allow access for ocean-going vessels to the Port of Corpus Christi. This deeper channel now delivers most of the water exchange between the Nueces/Mission-Aransas Estuaries and the Gulf of Mexico, which has reduced the flow through other shallow historical passes between these estuaries and the Gulf, causing them to fill in with sediments and close unless maintained through dredging (e.g. Fish Pass, Cedar Bayou). As a result of historical passes closing due to the already permitted deepening of the Aransas Pass, this channel is now the main route available for larvae to recruit from the Gulf to local estuaries. It is unclear how additional alterations to the depth of the Aransas Pass and adjacent waters will alter hydrodynamics in this channel, or other remaining channels, and affect the recruitment of estuarine dependent larvae. Below are several examples of important estuarine species that could be impactedMarine Scienc

Elevating Substance over Procedure: The Retroactivity of Miller v. Alabama under Teague v. Lane

This Article proposes a unique framework establishing that the United States Supreme Court’s decision in Miller v. Alabama, which forbids states from automatically sentencing juveniles to life imprisonment without any meaningful opportunity for release, must apply retroactively to hundreds of juveniles whose convictions and life sentences were already final at the time of the decision. Such a framework is timely and critical. The lower state and federal courts are divided on the question, and the Supreme Court is likely to settle the issue within the next year. The Article reviews how, absent guidance from the Supreme Court, a host of states, led most recently by Michigan, have invoked the Miller majority’s statement that it was merely requiring states to follow a “certain process” before sentencing a juvenile to life imprisonment without parole. By this reasoning, Miller is not retroactive under the Supreme Court’s federal retroactivity doctrine established by Teague v. Lane. The Court has always applied new substantive rules retroactively under Teague, while it has never done so for a new procedural rule. The Article rejects this “process” language as a basis for resolving whether Miller is retroactive. It concludes that Miller in fact has little to do with process and is instead primarily concerned with sentencing outcomes for youth. In striking down mandatory life without parole for juveniles, Miller adapted the individualized sentencing requirement from Woodson v. North Carolina, which invalidated the mandatory death penalty. This individualized sentencing requirement obligates states to always offer juveniles a sentencing outcome carrying the possibility of release and to consider the essential, mitigating fact of youth before imposing an irrevocable life sentence. These obligations are inherently substantive. By contrast, Miller’s alleged procedural component is undefined and collateral to its substantive altering of juvenile sentencing. Miller therefore announces a substantive rule that must apply retroactively

The distribution of estuarine fish larvae: nutritional condition and co-occurrence with predators and prey

Fish larvae were collected monthly between March and September 1997 in the Mira and Guadiana estuaries (southern Portugal). Hydrological parameters were registered and zooplankton samples were obtained simultaneously. Densities of fish larvae (ind.100 m(-3)) were calculated from 211 samples and larval nutritional condition measured as RNA/DNA ratios were obtained for 346 individuals, using a fluorimetric method for nucleic acid quantification. Correlating variables were further studied using multiple regression analysis in order to assess the relative importance of abiotic and biotic factors affecting within-year trends in abundance and nutritional condition of estuarine fish larvae. Results indicated that: 1) the abundance of fish larvae seems conditioned by temperature and predation; and 2) their nutritional condition is dependent on temperature and prey availability. Temperature is an important variable structuring estuaries and therefore conditions the behaviour and physiology of fish larvae. Furthermore, the co-occurrence of predators and larvae might be related to similar feeding patterns or comensalism. Whenever feeding conditions are suitable, they usually determine enhanced growth and nutritional condition. However, predation seems to control this latter relationship through its effect on larval mortality. (C) 2000 Editions scientifiques et Medicales Elsevier SAS.info:eu-repo/semantics/publishedVersio