Seagrass meadows are critically important coastal habitats, but they are undergoing rapid global declines linked to degradation of coastal catchments and the expansion of development in coastal ...zones, which can lead to increased deposition of terrigenous sediments onto seagrass meadows. In the Asia-Pacific region, which includes the Great Barrier Reef, direct sedimentation effects are recognised as the major threat to seagrass growth and survival. However, tolerance to burial varies among species. Understanding thresholds for burial tolerance at the species-level is therefore critical to effective management of human impacts on seagrass meadows. This research examined the effects of sedimentation on two tropical seagrass species, Zostera muelleri and Halophila ovalis in an experimental mesocosm and field setting. The research suggests that shoot density in these species declines significantly at burial depths of 5–7.5 mm in a mesocosm setting, with very low levels of growth observed above 10 mm burial depth. Fine sediments (including fine sands, silts and clays) appear to have a greater negative effect on shoot density in both species, compared to coarser sandy sediments. In situ, the effect of burial is less pronounced and is likely to be mitigated by a range of factors, including clonal integration. These species also demonstrate different adaptations to burial disturbance, including by resisting burial effects (Z. muelleri) or by regenerating from the buried rhizome after disturbance (H. ovalis).
•We tested the burial tolerance of two tropical seagrasses using estuarine sediments.•In a mesocosm setting, shoot density declines significantly at 5–7.5 mm burial depth.•Growth is very limited at burial depths of 10 mm or greater.•Fine sands and muds (<250 μm) have the strongest suppression effect.•The different adaptations of these species to burial disturbance are discussed.
In the sea 3 types of plants occur and they arePhytoplanktons, Seaweeds or Marine Algae and Seagrasses. Phytoplanktons are microscopic and free floating forms and they are the primary producers of ...the sea. Seaweeds or Marine Algae are macroscopic, attached or free floating plants.
The Indo-Malay Archipelago is regarded as a barrier that separates organisms of the Indian and Pacific Oceans. Previous studies of marine biota from this region have found a variety of biogeographic ...barriers, seemingly dependent on taxon and methodology. Several hypotheses, such as emergence of the Sunda Shelf and recent physical oceanography, have been proposed to account for the genetic structuring of marine organisms in this region. Here, we used six microsatellite loci to infer genetic diversity, population differentiation and phylogeographic patterns of
across the Indo-Malay Archipelago. Heterozygosities were consistently high, and significant isolation-by-distance, consistent with restricted gene flow, was observed. Both a neighbour joining tree based on
distance and Bayesian clustering revealed three major clusters of
. Our results indicate that phylogeographic patterns of
have possibly been influenced by glaciation and deglaciation during the Pleistocene. Recent physical oceanography such as the South Java Current and the Seasonally Reversing Current may also play a role in shaping the genetic patterns of
.
This is the dataset for an article published in Marine Environmental Research titled, 'Tolerance to aerial exposure influences distributional patterns in multi-species intertidal seagrass meadows', ...in October 2023. Following is the abstract for the paper for which this was the primary data:
Multi-specific seagrass meadow assemblages dominate most tropical intertidal regions but the relative role of environmental stress in determining distribution patterns is still uncertain. Here we combine observational and experimental approaches to examine aerial exposure as a factor driving species occurrence patterns in intertidal meadows of the Andaman archipelago, where up to 6 seagrass species co-occur. In the studied meadow, patterns of exposure did not map onto distance from the coast, instead creating a patchy matrix of exposure, based on fine-scale bathymetric differences. Distributional surveys showed that seagrass species were similarly patchy, often tracking the degree of aerial exposure during low tide. While some species (Halophila ovalis, Halophila minor, and Thalassia hemprichii) frequently occurred in submerged or subtidal areas and were rarely found in completely exposed areas, other species (Cymodocea rotundata, Halophila beccarii, and Halodule uninervis) also occupied areas that were subject to partial or complete aerial exposure during low tide. To confirm this pattern, we used field-based transplant experiments, employing a natural gradient of tidal exposure to subject six seagrass species to different desiccation exposure times. After a month, H. beccarii and H. uninervis transplants survived in areas that sustained more than 3 h of aerial tidal exposure without significant mortality, compared with other species (H. ovalis, H. minor, T. hemprichii, C. rotundata) that showed dramatic shoot mortality at the same exposure regimes. For all species, 4 h represented the upper limit of exposure, in both experimental and distributional studies. However, despite their wider tolerance of exposure to air, H. beccarii and H. uninervis did not dominate the entire meadow. This could be a result either of their poor tolerance to other environmental factors or their lower competitive abilities among other mechanisms. This suggests that in tropical multi-specific meadows, strong environmental filters could override clear intertidal zonation to create patchy matrices based on species tolerances.
As seen in Chapter 6, the Oligocene-Miocene boundary was not such a significant event for larger benthic foraminifera as the sharply defined Cretaceous-Paleocene boundary. Indeed, almost 80% of ...species survived the boundary into the Miocene. Although most of the Miocene superfamilies are extant, provincialism is prominent at both the generic and specific levels. Following the initial transoceanic migrations of larger benthic foraminifera between the American and the Tethyan provinces, facilitated by the series of global sea-level regressions, this migration stopped after rising sea-level in the early Oligocene separating the American from the other larger benthic provinces (see BouDagher-Fadel and Price,
The Project of the Mediterranean Initiative on Taxonomy (MIT) aims at carrying out in the Mediterranean area the objectives of the Global Taxonomy Initiative (GTI), within the outline of the ...Convention on Biological Diversity (CBD). As an exemplification the present work reports, through the knowledge on vegetable taxonomy, an evaluation of the state of taxonomy of marine vegetable organisms in the Mediterranean Countries and in particular in Italy. An accurate evaluation on the state of taxonomy of the marine vegetable organisms in the Mediterranean Countries needs data collection from scientists and scientific organisations operating within every single Nation. Available statistical data on the distribution of Phycologists in the Mediterranean area, shows a significant but not always sufficient number of specialists according to the development of the coastal area in Spain, France, Italy, Greece, Turkey, Russia, Romania, and Israel. Qualified presences can also be found in Egypt and Tunisia. All Countries need a generational renewal of taxonomy specialists, programmed by Governments and not trusted to the chance of personal choices or to a successful University career. All Countries need to increase their number of taxonomists and to provide them with a higher level of specialisation in order to manage the Mediterranean Initiative on Taxonomy (MIT) and to carry out the Convention on Biological Diversity (CBD).
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
With particular reference to Gatty's British Sea-Weeds and Eliot's 'Recollections of Ilfracombe', this article takes an ecocritical approach to popular writings about seaweed, thus illustrating the ...broader perception of the natural world in mid-Victorian literature. This is a discursive
exploration of the way that the enthusiasm for seaweed reveals prevailing ideas about propriety, philanthropy and natural theology during the Victorian era, incorporating social history, gender issues and natural history in an interdisciplinary manner. Although unchaperoned wandering upon
remote shorelines remained a questionable activity for women, 'seaweeding' made for a direct aesthetic engagement with the specificity of place in a way that conforms to Barbara Gates's notion of the 'Victorian female sublime'. Furthermore, while women's contributions often received an uneven
reception within the masculine institutions of professional science, marine botany proved to be a more accommodating area for participation. At Ilfracombe, Eliot wrote that she believed collecting and naming was a means to achieve distinct and definite ideas in her understanding of the
world. The argument is developed that many needed to reorient their personal cosmologies in order to make sense of, and impose meaning upon, an uncertain world, thus contributing to the great debate about evolution.
Assessment of floral biodiversity along the Karnataka coast carried out during 2005-2006 revealed theoccurrence of 53 phytoplankton, 78 seaweed and 2 seagrass species from estuary, intertidal, open ...seaand island ecosystems. Phytoplankton from Karnataka coast was dominated by diatoms and five speciesof toxic forms. The phytoplankton diversity was found to be the richest in estuarine areas than in sea andintertidal regions. Among the 78 species of seaweeds belonging to 52 genera and 28 families, exploitablequantity of commercially important seaweeds were algin yielding Sargassum ilicifolium from grids 8and 9 and agaroid yielding Gracilariopsis lemaneiformis from grids 3 and 4. Seagrasses were representedby Ruppia maritima and Halophila beccarii from the Swarna - Sita, Chakra, Haladi and Kollur estuarinesystems including Venkatapur. The study is the first comprehensive account of the floral biodiversityoccurring along the entire Karnataka coast. Occurrence of red seaweed Gracilariopsis lemaneiformisin certain estuarine areas indicates the possibility of its farming in the estuary.
India is still amongst the countries with the lowest rice yields, with the national average of 1,930 kg/ha. Seventypercent of the 414 rice growing districts reports yield lower than the national ...average, clearly Indicating that well; after the advent of high yielding technology, a sizable area is categorized as low producing.
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