67 research outputs found
Comparing the Invasibility of Experimental âReefsâ with Field Observations of Natural Reefs and Artificial Structures
Natural systems are increasingly being modified by the addition of artificial habitats which may facilitate invasion. Where invaders are able to disperse from artificial habitats, their impact may spread to surrounding natural communities and therefore it is important to investigate potential factors that reduce or enhance invasibility. We surveyed the distribution of non-indigenous and native invertebrates and algae between artificial habitats and natural reefs in a marine subtidal system. We also deployed sandstone plates as experimental âreefsâ and manipulated the orientation, starting assemblage and degree of shading. Invertebrates (non-indigenous and native) appeared to be responding to similar environmental factors (e.g. orientation) and occupied most space on artificial structures and to a lesser extent reef walls. Non-indigenous invertebrates are less successful than native invertebrates on horizontal reefs despite functional similarities. Manipulative experiments revealed that even when non-indigenous invertebrates invade vertical âreefsâ, they are unlikely to gain a foothold and never exceed covers of native invertebrates (regardless of space availability). Community ecology suggests that invertebrates will dominate reef walls and algae horizontal reefs due to functional differences, however our surveys revealed that native algae dominate both vertical and horizontal reefs in shallow estuarine systems. Few non-indigenous algae were sampled in the study, however where invasive algal species are present in a system, they may present a threat to reef communities. Our findings suggest that non-indigenous species are less successful at occupying space on reef compared to artificial structures, and manipulations of biotic and abiotic conditions (primarily orientation and to a lesser extent biotic resistance) on experimental âreefsâ explained a large portion of this variation, however they could not fully explain the magnitude of differences
High spatial resolution analysis of ferromanganese concretions by LA-ICP-MSâ
A procedure was developed for the determination of element distributions in cross-sections of ferromanganese concretions using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The effects of carrier flow rates, rf forward power, ablation energy, ablation spot size, repetition rate and number of shots per point on analyte intensity were studied. It is shown that different carrier gas flow rates are required in order to obtain maximum sensitivities for different groups of elements, thus complicating the optimisation of ICP parameters. On the contrary, LA parameters have very similar effects on almost all elements studied, thus providing a common optimum parameter set for the entire mass range. However, for selected LA parameters, the use of compromise conditions was necessary in order to compensate for relatively slow data acquisition by ICP-MS and maintain high spatial resolution without sacrificing the multielemental capabilities of the technique. Possible variations in ablation efficiency were corrected for mathematically using the sum of Fe and Mn intensities. Quantification by external calibration against matrix-matched standards was successfully used for more than 50 elements. These standards, in the form of pressed pellets (no binder), were prepared in-house using ferromanganese concentrates from a deep-sea nodule reference material as well as from shallow-marine concretions varying in size and having different proportions of three major phases: aluminosilicates, Fe- and Mn-oxyhydroxides. Element concentrations in each standard were determined by means of conventional solution nebulisation ICP-MS following acid digestion. Examples of selected inter-element correlations in distribution patterns along the cross-section of a concretion are given
Significant discharge of CO2 from hydrothermalism associated with the submarine volcano of El Hierro Island
The residual hydrothermalism associated with submarine volcanoes, following an eruption event, plays
an important role in the supply of CO2 to the ocean. The emitted CO2 increases the acidity of seawater.
The submarine volcano of El Hierro, in its degasification stage, provided an excellent opportunity to
study the effect of volcanic CO2 on the seawater carbonate system, the global carbon flux, and local
ocean acidification. A detailed survey of the volcanic edifice was carried out using seven CTD-pH-ORP
tow-yo studies, localizing the redox and acidic changes, which were used to obtain surface maps of
anomalies. In order to investigate the temporal variability of the system, two CTD-pH-ORP yo-yo
studies were conducted that included discrete sampling for carbonate system parameters. Meridional
tow-yos were used to calculate the amount of volcanic CO2 added to the water column for each
surveyed section. The inputs of CO2 along multiple sections combined with measurements of oceanic
currents produced an estimated volcanic CO2 flux = 6.0 105 Âą 1.1 105 kg dâ1 which is ~0.1% of global
volcanic CO2 flux. Finally, the CO2 emitted by El Hierro increases the acidity above the volcano by ~20%.En prens
The Role of the Clean Development Mechanism in Achieving Chinaâs Goal of a Resource Efficient and Environmentally Friendly Society
This paper examines the impact of the clean development mechanism (CDM) on Chinaâs progress in building a resource-efficient and environmentally friendly society, referred to as a dual-goal society. It presents Chinaâs CDM activities from the perspective of policy directions, administrative arrangements and capacity building as well as outlines the regional trends and distribution of CDM projects across Chinaâs 30 provinces. Based on regression analysis of 2006â2009 panel data, the research was able to provide estimates at provincial level of the impacts of CDM activities on Chinaâs CO2 emission intensity, SO2 emission intensity and industrial dust emission intensity. The study concludes that the active CDM projects are mainly located in the less-developed central and west China where they have provided increased opportunities for sustainable development. Furthermore, the successful implementation of CDM projects across the country has significantly decreased the emission intensity of CO2, SO2 and industrial dust, which means that these activities have enhanced Chinaâs ability to build the desired dual-goal society
Marine Biodiversity of Aotearoa New Zealand
The marine-biodiversity assessment of New Zealand (Aotearoa as known to MÄori) is confined to the 200 nautical-mile boundary of the Exclusive Economic Zone, which, at 4.2 million km2, is one of the largest in the world. It spans 30° of latitude and includes a high diversity of seafloor relief, including a trench 10 km deep. Much of this region remains unexplored biologically, especially the 50% of the EEZ deeper than 2,000 m. Knowledge of the marine biota is based on more than 200 years of marine exploration in the region. The major oceanographic data repository is the National Institute of Water and Atmospheric Research (NIWA), which is involved in several Census of Marine Life field projects and is the location of the Southwestern Pacific Regional OBIS Node; NIWA is also data manager and custodian for fisheries research data owned by the Ministry of Fisheries. Related data sources cover alien species, environmental measures, and historical information. Museum collections in New Zealand hold more than 800,000 registered lots representing several million specimens. During the past decade, 220 taxonomic specialists (85 marine) from 18 countries have been engaged in a project to review New Zealand's entire biodiversity. The above-mentioned marine information sources, published literature, and reports were scrutinized to give the results summarized here for the first time (current to 2010), including data on endemism and invasive species. There are 17,135 living species in the EEZ. This diversity includes 4,315 known undescribed species in collections. Species diversity for the most intensively studied phylum-level taxa (Porifera, Cnidaria, Mollusca, Brachiopoda, Bryozoa, Kinorhyncha, Echinodermata, Chordata) is more or less equivalent to that in the ERMS (European Register of Marine Species) region, which is 5.5 times larger in area than the New Zealand EEZ. The implication is that, when all other New Zealand phyla are equally well studied, total marine diversity in the EEZ may be expected to equal that in the ERMS region. This equivalence invites testable hypotheses to explain it. There are 177 naturalized alien species in New Zealand coastal waters, mostly in ports and harbours. Marine-taxonomic expertise in New Zealand covers a broad number of taxa but is, proportionately, at or near its lowest level since the Second World War. Nevertheless, collections are well supported by funding and are continually added to. Threats and protection measures concerning New Zealand's marine biodiversity are commented on, along with potential and priorities for future research
A Tri-Oceanic Perspective: DNA Barcoding Reveals Geographic Structure and Cryptic Diversity in Canadian Polychaetes
Although polychaetes are one of the dominant taxa in marine communities, their distributions and taxonomic diversity are poorly understood. Recent studies have shown that many species thought to have broad distributions are actually a complex of allied species. In Canada, 12% of polychaete species are thought to occur in Atlantic, Arctic, and Pacific Oceans, but the extent of gene flow among their populations has not been tested.Sequence variation in a segment of the mitochondrial cytochrome c oxidase I (COI) gene was employed to compare morphological versus molecular diversity estimates, to examine gene flow among populations of widespread species, and to explore connectivity patterns among Canada's three oceans. Analysis of 1876 specimens, representing 333 provisional species, revealed 40 times more sequence divergence between than within species (16.5% versus 0.38%). Genetic data suggest that one quarter of previously recognized species actually include two or more divergent lineages, indicating that richness in this region is currently underestimated. Few species with a tri-oceanic distribution showed genetic cohesion. Instead, large genetic breaks occur between Pacific and Atlantic-Arctic lineages, suggesting their long-term separation. High connectivity among Arctic and Atlantic regions and low connectivity with the Pacific further supports the conclusion that Canadian polychaetes are partitioned into two distinct faunas.Results of this study confirm that COI sequences are an effective tool for species identification in polychaetes, and suggest that DNA barcoding will aid the recognition of species overlooked by the current taxonomic system. The consistent geographic structuring within presumed widespread species suggests that historical range fragmentation during the Pleistocene ultimately increased Canadian polychaete diversity and that the coastal British Columbia fauna played a minor role in Arctic recolonization following deglaciation. This study highlights the value of DNA barcoding for providing rapid insights into species distributions and biogeographic patterns in understudied groups
Organotin compounds in surface sediments of the Southern Baltic coastal zone: a study on the main factors for their accumulation and degradation
Abstract Sediment samples were collected in the Gulf of
GdaĹsk, and the Vistula and Szczecin Lagoonsâall located
in the coastal zone of the Southern Baltic Seaâjust after the
total ban on using harmful organotins in antifouling paints on
ships came into force, to assess their butyltin and phenyltin
contamination extent. Altogether, 26 sampling stations were
chosen to account for different potential exposure to organotin
pollution and environmental conditions: from shallow and
well-oxygenated waters, shipping routes and river mouths,
to deep and anoxic sites. Additionally, the organic carbon
content, pigment content, and grain size of all the sediment
samples were determined, and some parameters of the nearbottom
water (oxygen content, salinity, temperature) were
measured as well. Total concentrations of butyltin compounds
ranged between 2 and 182 ng Sn gâ1 d.w., whereas phenyltins
were below the detection limit. Sediments from the Gulf of
GdaĹsk and Vistula Lagoon were found moderately contaminated
with tributyltin, whereas those from the Szczecin
Lagoon were ranked as highly contaminated. Butyltin degradation
indices prove a recent tributyltin input into the sediments
adjacent to sites used for dumping for dredged harbor
materials and for anchorage in the Gulf of GdaĹsk (where two
big international ports are located), and into those collected in
the Szczecin Lagoon. Essential factors affecting the degradation
and distribution of organotins, based on significant correlations
between butyltins and environmental variables, were
found in the study area
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