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  • 1
    In: Journal of Earth and Environmental Sciences Research, Scientific Research and Community Ltd, ( 2023-9-30), p. 1-34
    Abstract: The location and topography of the 1,300 km Baja California peninsula west of the Sonoran Desert provide the most extreme conditions for mangrove forest growth in the Northern Hemisphere. Despite their small size, however, the dwarf shrub mangroves ( 〈 2 to 4 m) are important for global CO2 sequestration, and monitoring of their expansion or decline is needed as part of assessing global carbon fluxes and biodiversity. Mangrove distributions at 42 coastal sites in 1972/73 are compared to historical accounts and modern data. These data show that there has been almost no northward migration of Rhizophora mangle during the past century although Avicennia germinans and Laguncularia racemosa have spread north on the Gulf Coast. The dwarf mangrove plant biodiversity in 1972/73 is related to geoform, temperature (T) and seasonal precipitation (P), but mangrove species cluster by annual P and T. The present northernmost Baja California mangrove limits are at 26.79° N on the Pacific Coast, and at 29.04° N on the Gulf Coast mainland, close to limits recorded in 1921. However, there are notable (46 to 4,649 ha) increases in areal cover and canopy height at these northern sites, and in other areas remote from urbanization. Case histories for seven locations point to increasing frequency and severity of tropical storms as main drivers of change on both coasts. However, anthropogenic changes from tourism promotion are major hazards to survival of the Gulf Coast forests, despite international, governmental and public efforts to legislate nature preserves. On the Pacific Coast, rising seawater temperatures may create coastal current conditions that potentially allow the extension of red and white mangrove ranges into northwestern Baja California. However, hazards associated with ocean warming that promotes tropical storm frequency and intensity can have predominantly negative impacts on mangrove production. These extreme hazards counteract the benefits of local and regional protection and management efforts
    Type of Medium: Online Resource
    ISSN: 2634-8845
    Language: Unknown
    Publisher: Scientific Research and Community Ltd
    Publication Date: 2023
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  • 2
    Online Resource
    Online Resource
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-10-4)
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-10-4)
    Abstract: The on-going decline in Arctic sea ice represents a significant loss of habitat for sea ice algae, which are a major contributor to primary production in the Arctic. Data on sea ice algal production is limited due to difficulties in both accessing sea-ice and sampling under-ice algae. Compound-specific isotope analysis (CSIA) of amino acids (AAs) is emerging as a powerful tool to trace element origins and biogeochemical processes in marine food webs and may address the knowledge gaps in sea ice algal productivity dynamics. Here we measured δ 13 C-AA and δ 15 N-AA in natural communities of sea ice and pelagic algae collected from regions offshore Labrador and Nunavut, Canada. Significant difference in δ 13 C-AA patterns between sea ice and pelagic algae was observed in different size classes. This difference was further supported by multivariate analyses based on normalized δ 13 C of essential amino acids (EAAs), which demonstrated a clear separation between sea ice and pelagic algae. Beta (β) values and trophic position (TP) calculated from δ 15 N of Glutamic Acid and Phenylalanine (Phe) and ∑V parameter for microbial resynthesis indicated a slightly higher heterotrophic biomass in pelagic and sea ice samples as compared to cultured samples. This finding is consistent with the Phe-normalized δ 15 N of Alanine and Threonine, which provided better separations between sea ice/pelagic algae and other end-member groups. Overall, our study provides first insights into the potential differences in δ 13 C-AA and δ 15 N-AA patterns between sea ice and pelagic algae and suggests carbon of sea ice origins may be distinguished from pelagic sources using CSIA-AA approach. These observations highlight the potential of CSIA-AA to estimate proportional contributions of sea ice and pelagic algae to export production and efficiency of benthic-pelagic coupling in polar marine environments.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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