24 research outputs found

    Range extension of the macroalgae Anadyomene stellata (Wulf. In Jacquin) C. Agardh and re-appearance of Caulerpa sertularioides (S. G. Gmel.) M. Howe in the Lower Laguna Madre, Texas

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    We report one new species of macroalgae, Anadyomene stellata, for the Lower Laguna Madre of Texas, and range extensions that have occurred in the past 16 years for this and four other green algae. Anadyomene stellata occurs only as an epiphyte on the red macroalgae, Digenia simplex. Caulerpa sertularioides has not been seen in the Lower Laguna Madre since 1962. It has either been present in cryptic habitats for 50 years near the Lower Laguna Madre or has recently expanded its range again into the Lower Laguna Madre. Ecological consideration of the presence of these species is discussed

    Range extensions of the seaweeds Codium taylorii and Caulerpa prolifera into the lower Laguna Madre, Texas

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    Between January 1999 and April 2000 two chlorophyte algae, Codium taylorii Silva and Caulerpa prolifera F. obovata (Forsskal) Lamouroux were found in the lower Laguna Madre (LLM). Both are coenocytic algae and are members of the chlorophyte class Bryopsidophyceae ( van den Hoek et al. 1995). The species descriptions in Taylor (1960) were used in the identification of the specimens. Her barium specimens have been deposited at the University of Texas- Pan American Coastal Studies Laboratory (accession numbers COlO - C. prolifera, COl 1 - C. taylorii) , University of California at Berkeley (UC 1753606 - C. taylorii) , University of Michigan and the University of Texas Marine Science Institute

    Flowering and seed production in the subtropical seagrass, Halodule wrightii (shoal grass)

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    Reproductive structures of the seagrass, Halodule wrightii Ascherson (shoal grass) are cryptic and ephemeral, but were found on several occasions at several sites over more than a decade in the subtropical Laguna Madre (USA). Structures align with descriptions for H. wrightii. Male, but no female flowers were found, but the numerous fruit-bearing shoots imply the occurrence of pistillate flowers. Mean seed bank density was 890 seeds m-2 (1900–5200 m-2). Sexual reproduction in H. wrightii is more common than previously believed and the seed bank reserve may contribute to its ecological role as a colonizer of disturbed sediments

    Engaging Minority Students in Sustainable Bioenergy and Water Quality through an Education and Research Network

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    Growing energy demand is connected to water availability and climate change and it places additional stress on the environment. Thereby, It is critical to prepare the next generation of engineers and professionals to face the challenges in bioenergy, expand sustainable alternatives to fossil fuels1 and enable climate-smart agriculture2,3. To address this challenge, a career-oriented multidisciplinary educational model is being implemented at three minority-serving institutions. This paper discusses the foundation of this educational program, which provides a robust response to the current sustainability issues by conducting multidisciplinary coordinated education, mentoring, research and extension activities among multiple universities and laboratories. This educational program aims to accomplish the ultimate goal of increasing minority participation in pursuing advanced degrees in STEM and attaining a diverse highly trained and skillful workforce with a strong pragmatic, experimental, analytical and computational background as well as scientific literacy in sustainable energy and the energywater nexus. In this model, students are expected to gain knowledge and understanding of the operational complexity of sustainable energy systems from source-to-use. Students will be able to conduct research and discovery from the feedstock properties passing through the conversion technologies to the mathematical modeling and optimization of the whole bioenergy value chain. In addition, students will be able to translate their findings in the laboratory regarding water quality and treatment into operational parameters to be included in comprehensive water systems models

    Comparison of leaf-clipping and leaf-piercing techniques as applied to the seagrass Syringodium filiforme

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    Leaf elongation rates of the seagrass Syringodium filiforme (Kütz., 1860) were assessed at two sites in a subtropical lagoon of Texas on eleven occasions from January 1996 to April 1997 using two methods, clipping and leaf piercing (marking) to estimate leaf growth. Pierced shoots grew at a significantly faster rate than clipped shoots irrespective of site. Clipping underestimated leaf elongation by 30%–38%, although differences at individual sites were as high as 69%–72%. Underestimation of leaf growth rate derived by clipping could be corrected using a site-specific linear regression relationship between leaf growth rates determined by clipping and piercing methods. The percent difference in overall leaf growth rate during the 14-mo study was 55% (4.47 mm d–1 pierced vs 2.44 mm d–1 clipped leaves). Fastest growth occurred during summer with rates of pierced leaves ranging from 8 to 11 mm d–1, which was generally two to three times that of clipped leaves. Highest leaf growth rates for clipped leaves never exceeded 4 mm d–1, regardless of site. We suggest that use of the leaf-clipping method in S. filiforme is appropriate when leaf growth rates are to be compared among sites or treatments and when true growth rate values are not critical

    Productivity estimation in Halodule wrightii: comparison of leaf-clipping and leaf-marking techniques, and the importance of clip height

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    We compared estimates of Halodule wrightii leaf growth rates obtained from leaf-clipping and leaf-piercing methods in a south Texas lagoon. Leaf clipping underestimated leaf production from 15 to 37% in winter and 25 to 60% in summer relative to leaf piercing. The underestimation of leaf-clipping derived growth rates were corrected using a linear regression between leaf growth rates determined by leaf-clipping and leaf-piercing methods. To examine the effect of clip height on H. wrightii leaf growth rate estimation, leaves were clipped at 0, 2, 4, 6, and 8 cm above the sediment. Leaves clipped at 2 cm exhibited the fastest leaf growth rate (average = 3.66 mm d–1) while leaves clipped at 8 cm had the slowest rate (average = 2.30 mm d–1). Depressed leaf growth rates for 8 cm clip height were likely due to the slowing of growth rate with increasing leaf age. Reduced growth rate for the 0 cm clip height treatment may be attributable to removal of nearly all photosynthetic tissue and limited below-ground resources. In design of leaf-clipping studies, it is suggested that the selection of clip height and the period of growth after clipping be optimized for each season of a study

    The Biological Flora of Coastal Dunes and Wetlands: Avicennia germinans (L.) L.

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    Avicennia germinans (L.) L. is a pantropical, subtropical, and occasionally warm-temperate mangrove species that occurs on shorelines that have a broad horizontal tidal range. Also known as black mangrove, stands typically develop under anoxic, water-logged conditions in substrates of silt or clay. Black mangrove can tolerate salinity values ranging from 0 to 90 parts per thousand. Salt is excreted from salt glands on both leaf epidermal surfaces, and aerosol salt spray and salt crystals are frequently observed on the upper leaf epidermis. Avicennia germinans is viviparous. The embryos have no dormancy requirements, and there is no seed bank. This mangrove species has the northernmost distributional range of any mangrove species in North America. It occurs in Louisiana and northern Florida. Color-infrared photography and airborne video imagery techniques have been used successfully to map stands of black mangrove on subtropical coastal shorelines. Reforestation efforts using seedlings and saplings have been successful in several areas of the tropics and subtropics. Avicennia germinans stands play an important role in ecosystem functions as a natural barrier to coastal erosion caused by tropical storms, as habitat for a wide range of organisms in intertidal food chains, and as a carbon repository

    Biological Flora of the Tropical and Subtropical Intertidal Zone: Literature Review for Rhizophora mangle L.

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    Rhizophora mangle L. is a tropical and subtropical mangrove species that occurs as a dominant tree species in the intertidal zone of low-energy shorelines. Rhizophora mangle plays an important role in coastal zones as habitat for a wide range of organisms of intertidal food webs, as a natural barrier to coastal erosion, and as carbon sequestration. A review of mangrove literature has been performed, but a review specifically on red mangroves has not. The approach was to cover a broad range of topics with a focus on topics that have seen significant work since the 1970s. This review includes a brief introduction to red mangroves and then focuses on the following topics: biogeography, habitats and zonation, geomorphological interactions, taxonomy, histology, anatomy, physiological ecology, productivity, biomass, litter, reproduction, population biology, plant communities, interactions with other species, impacts of storms, reforestation, remote sensing, modelling, and economic importance

    Re-occurrence of the tropical green macroalga, Penicillus capitatus (Chlorophyta: Bryopsidales), in Lower Laguna Madre of South Texas.

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    The siphonaceous green alga Penicillus capitatus Lamarck is a common macroalga of the Carribean and Gulf of Mexico (Littler & Littler 2000). This shaving brush-shaped macroalga was a common inhabitant of the Lower Laguna Madre Texas (LLM) until about 40 years ago when the population was decimated following a salinity decline in the fall of 1959, another salinity reduction due to Hurricane Carla in 1961, and finally a severe freeze in 1962 (Sorensen 1963). Since that time, there have been no reports of P. capitatus in the LLM. During a reconnaissance trip in July 2006, a small population was found in the southern portion of the LLM. The species descriptions by Taylor (1960) and Sorensen (1979) were used in the identification of specimens. Herbarium specimens have been deposited in the herbaria of The University of Texas-Pan American Coastal Studies Laboratory (accession number C012), and the University of Texas at Austin Marine Science Institute

    A Comparison of Salinity Effects from Hurricanes Dolly (2008) and Alex (2010) in a Texas Lagoon System

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    A comparison of salinity effects from hurricanes Dolly (2008) and Alex (2010) in a Texas lagoon system.Hurricanes are not uncommon along the Gulf of Mexico coast, but there are few studies of the effects they have on coastal embayments. Hurricanes Dolly (2008) and Alex (2010) were both Category 2 storms affecting the Lower Laguna Madre (LLM) of Texas. Surveys were performed to assess poststorm water quality after landfall of both storms at up to 18 sample stations. The main difference between storm effects was salinity reduction because of stormwater input from the watershed. Effects from Hurricane Dolly were of short duration and small magnitude, whereas the effects from Hurricane Alex were extensive and lasted more than a month. Differences in spatial patterns in salinity were significantly more pronounced across the LLM than were temporal differences. Precipitation of 50–100 cm caused stormwater discharge to exceed 1000 m s−1 to the LLM during the Alex event and depressed salinity over more than three-fourths (ca. 500 km2) of the estuary for 2 months. Storm-related effects on water-column physiochemistry were persistently lowest near freshwater drains (Arroyo Colorado). Salinity remained less than 5 for more than 2 months during the Alex freshet. Freshwater input from Hurricane Dolly was relatively minor because the storm precipitation was largely restricted to the small Arroyo Colorado watershed. Effects from Alex were delayed but were greater because of the bulk of the precipitation falling in the Rio Grande/Rio Bravo drainage basin in México. The greatest impact from that freshwater disturbance was the loss of seagrasses after prolonged exposure to hyposalinity. Hurricanes Dolly and Alex both affected the LLM but with contrasting impacts that reflected spatial and meteorological differences between the two storms
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