Input of river-derived sediment to the New Zealand continental shelf: I. Mass

The input of river-borne sediments to the New Zealand continental shelf has been calculated for all the major rivers and basins in New Zealand. South Island yields 284 ± 40 × 10⁶ tonnes per year of sediment from a land area of 152 977 km² and North Island yields 105 ± 9·4 × 10⁶ tonnes per year from a land area of 114 621 km². Particularly high discharges are noted off the west coast of South Island and east coast of North Island and result in higher offshore sedimentation there. The data are compatible with measured sedimentation rates on the New Zealand continental shelf. The specific sediment yield from South Island is amongst the highest previously recorded.     

Sediment variability in offshore sampling areas

From two to four different sediment types were found in each of six offshore sampling areas in western Bay of Plenty, New Zealand. The size of the areas ranged from 7.7 km² to 64.6 km², and the average depths ranged from 36 m to 168 m. Sediments may thus vary widely within areas plotted as homogeneous on large‐scale (1:200 000) sediment charts.     

Anthropogenic influences on shoreline and nearshore evolution in the San Francisco Bay coastal system

Analysis of four historical bathymetric surveys over a 132-year period has revealed significant changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of San Francisco Bay estuary. From 1873 to 2005 the San Francisco Bar vertically-eroded an average of 80 cm over a 125 km² area, which equates to a total volume loss of 100 ± 52 million m³ of fine- to coarse-grained sand. Comparison of the surveys indicates the entire ebb-tidal delta contracted radially, with the crest moving landward an average of 1 km. Long-term erosion of the ebb-tidal delta is hypothesized to be due to a reduction in the tidal prism of San Francisco Bay and a decrease in coastal sediment supply, both as a result of anthropogenic activities. Prior research indicates that the tidal prism of the estuary was reduced by 9% from filling, diking, and sedimentation. Compilation of historical records dating back to 1900 reveals that a minimum of 200 million m³ of sediment has been permanently removed from the San Francisco Bay coastal system through dredging, aggregate mining, and borrow pit mining. Of this total, ∼54 million m³ of sand-sized or coarser sediment was removed from central San Francisco Bay. With grain sizes comparable to the ebb-tidal delta, and its direct connection to the bay mouth, removal of sediments from central San Francisco Bay may limit the sand supply to the delta and open coast beaches.     

Variation of Icelandic and Hawaiian magmatism: evidence for co-pulsation of mantle plumes?

Based on published estimates of areal extent, thickness and dating of igneous rocks related to formation of the North Atlantic Volcanic Province, we calculate the magmatic production since the first reported magmatism at 70 Ma until present. We relate the magmatism to the Icelandic Plume and estimate the total volumetric production to 22.1 × 10⁶ km³. The magmatic production varied significantly with time, with a clear maximum of 55.5 m³/s around continental break-up at ca. 54 Ma. The lowest production is estimated at 4 m³/s, increasing to 7 m³/s at ca. 23 Ma. Two other pulses with increased activity are found around 40 Ma and in the late Miocene (10–5 Ma). The variations in productivity are consistent with a plume pulsing with a periodicity of ca. 15 million years. The same periodicity and relative timing is found for the Hawaiian Plume. If confirmed, these observations suggest that both plumes originate within the thin boundary layer near the Core-Mantle Boundary. This hypothesis may imply periodic heating of the earth’s core with subsequent heat-release to the mantle and increased global plume activity.     

Identifying biologically and physically special or unique sites for inclusion in the protected area design for the Great Barrier Reef Marine Park

A method to identify special and/or unique sites was developed when reviewing the zoning of the Great Barrier Reef Marine Park. Fifty-three (totalling approximately 10,445 km²) of 408 sites were identified as special or unique based on the amount, detail and nature of justification; geographic explicitness; type of information sources; number of independent sources; and national or international obligations. All but four special or unique sites increased in protection after the Zoning Plan was revised, increasing the area of no-take protection for all special or unique sites from 1614 km² (15.4%) to 4013 km² (38.4%).     

Calculated sea area of the New Zealand 200 nautical mile Exclusive Economic Zone

A calculation of the area of the New Zealand 200 nautical mile Exclusive Economic Zone is presented with definitions, cartographic methods, and calculations based on areas of quadrilaterals of the earth's surface of 1° extent in latitude and longitude. An area of 1 181 487 square international nautical miles (4 053 049 km²), ± 0.377%, includes enclaves adjacent to the Chatham Rise and the Pukaki Rise retained for assessments related to fisheries research programmes.     

An evaluation of acoustic seabed classification techniques for marine biotope monitoring over broad-scales (>1 km) and meso-scales (10 m–1 km)

Acoustic seabed classification is a useful tool for monitoring marine benthic habitats over broad-scales (>1 km²) and meso-scales (10 m²–1 km²). Its utility in this context was evaluated using two approaches: by describing natural changes in the temporal distribution of marine biotopes across the broad-scale (4 km²), and by attempting to detect specific experimentally-induced changes to kelp-dominated biotopes across the meso-scale (100 m²). For the first approach, acoustic backscatter mosaics were constructed using sidescan sonar and multibeam echosounder data collected from Church Bay (Rathlin Island, Northern Ireland) in 1999, 2008 and 2009. The mosaics were manually segmented into acoustic facies, which were ground-truthed using a drop-video camera. Biotopes were classified from the video by multivariate exploratory analysis and cross-tabulated with the acoustic facies, showing a positive correlation. These results were integrated with bathymetric data to map the distribution of seven unique biotopes in Church Bay. Kappa analysis showed the biotope distribution was highly similar between the biotope maps, possibly due to the stability of bedforms shaped by the tidal regime around Rathlin Island. The greatest biotope change in this approach was represented by seasonal and annual changes in the growth of the seagrass, Zostera marina. In the second approach, sidescan sonar data were collected before and after the removal of 100 m² of kelp from three sites. Comparison of the data revealed no differences between the high-resolution backscatter imagery. It is concluded that acoustic seabed classification can be used to monitor change over broad- and meso-scales but not necessarily for all biotopes; its success depends on the type of acoustic system employed and the biological characteristics of the target biotope.     

Effects of MV Rena heavy fuel oil and dispersed oil on yellowtail kingfish early life stages

ABSTRACT

The grounding of the MV Rena has highlighted the lack of information concerning the effects of oil-related compounds on New Zealand marine life. Yellowtail kingfish (YTK), Seriola lalandi, embryos were exposed in static incubations to the water-accommodated fraction (WAF) of Rena heavy fuel oil as well as a similar preparation treated with the commercial dispersant Corexit 9500. Mortality in WAF treatments generally increased in association with total polycyclic aromatic hydrocarbon (tPAH) concentration over a 24-h period. Physical abnormalities were observed in some of the larvae exposed to WAF for 48 h. There was no survival in dispersed oil treatments after 24 h of exposure. These treatments had greater tPAH concentrations (2–53?µgL^?1) than equivalent WAF dilutions (0.2–1.5?µgL^?1?tPAH). Indications are that significant morbidity is induced in YTK at ecologically relevant tPAH concentrations. This highlights the need for further research into oil and dispersant toxicity in New Zealand marine species.     

Stream channels are narrower in pasture than in forest

In the Hakarimata Range, west of Hamilton, New Zealand, second‐order streams appear to be wider in native than in pasture catchments, whereas streams in pine plantations (18 years old) appear to be suffering active stream‐bank erosion. A working hypothesis to explain these observations was that pasture vegetation replacing original forest encroaches on the stream channel, causing it to become narrower. To test the hypothesis, channel widths were measured up stream and down stream of “transitions” from native forest to pasture in 20 streams of different size in marginal ranges of the Waikato Basin. Small streams (catchment area <1 km², width in forest <2 m) were found to be half the width in pasture reaches as in forest. The degree of channel narrowing decreased as stream size increased and was minimal in large streams (catchment area >30 km², width in forest >10 m). This narrowing of stream channels implies that native forest clearance in New Zealand has reduced stream channel habitat. A concern regarding riparian planting for stream restoration is that sediment stored in pasture stream banks could be mobilised if grasses are extinguished by shading, resulting in turbid streamwater and sedimentation of fines in the channel.     

Perspectives on effects-based management of New Zealand exclusive economic zone resources

Adoption of effects-based management, environmental effects-based management (EEM) or ‘learn as we go, is essential to open up access to all of New Zealand’s Maritime Exclusive Economic Zone (EEZ) resource base into the future. Utilising knowledge gained from ‘learn as we go’ and combining it with the integration of sectarian agendas and establishment of a central government EEZ agency empowered by an Act of Parliament will ensure future food and energy security is met. To achieve this integration of environmental effects management with security of access and stakeholder buy in is needed. Government hierarchies should not limit integration under EEM, policy should be non-separatist, and regions should be defined using ocean zoning. Future food and energy security can then be thought of in terms of environmental carrying capacity, moving away from regimes overly focussed on regulating for development. Ocean zoning could be used to assign property rights, with all activities subject to EEM regulation and enforcement of adaptive environmental standards through a central government EEZ Ocean Affairs agency. An overarching strategy to provide a framework guiding the development of New Zealand’s EEZ organisational infrastructure and decision making is needed to achieve this.     

Seasonality and interannual variability of freshwater inflow to a large oligohaline estuary in the Northern Gulf of Mexico

Quantity, timing, duration, and fluctuation of freshwater inflow are important factors affecting the development and health of aquatic and adjacent wetland ecosystems in coastal estuaries. This study assessed six decades of freshwater inflow from the Amite River, Tickfaw River, and Tangipahoa River watersheds to Lake Pontchartrain, a large oligohaline estuary in the Northern Gulf of Mexico, whose flood waters caused recent damage to the city of New Orleans in the aftermath of Hurricane Katrina. By utilizing the long-term (1940–2002) river discharge and climatic data from the three major tributary watersheds, monthly and annual freshwater inflows have been quantified and their spatial and temporal variations have been analyzed. On average, the three rivers discharged (±standard error) 0.27 ± 0.04 km³ freshwater monthly and 3.29 ± 0.15 km³ freshwater annually into the lake estuarine system, with the highest inflow from the Amite River (0.16 ± 0.03 m³ mon⁻¹, and 1.91 ± 0.09 km³ yr⁻¹) and the lowest inflow from the Tickfaw River (0.03 ± 0.00 km³ mon⁻¹, and 0.34 ± 0.02 km³ yr⁻¹). A distinct seasonality was evident with over 69% of the total annual inflow occurring during December and May (wet months) and with a low flow period from August to November (dry months). The monthly inflow during the wet months was positively correlated with the monthly precipitation (r² = 0.64), while the monthly inflow during the dry months was subject to evapotranspiration. Furthermore, the study found a 20-year low flow period from 1954–1973 (2.76 ± 0.24 km³ yr⁻¹) and a 24-year high flow period from 1975–1998 (3.84 ± 0.24 km³ yr⁻¹), coinciding with both the climate variation and population growth in the watersheds.     

A global map to aid the identification and screening of critical habitat for marine industries

Marine industries face a number of risks that necessitate careful analysis prior to making decisions on the siting of operations and facilities. An important emerging regulatory framework on environmental sustainability for business operations is the International Finance Corporation’s Performance Standard 6 (IFC PS6). Within PS6, identification of biodiversity significance is articulated through the concept of “Critical Habitat”, a definition developed by the IFC and detailed through criteria aligned with those that support internationally accepted biodiversity designations. No publicly available tools have been developed in either the marine or terrestrial realm to assess the likelihood of sites or operations being located within PS6-defined Critical Habitat. This paper presents a starting point towards filling this gap in the form of a preliminary global map that classifies more than 13 million km² of marine and coastal areas of importance for biodiversity (protected areas, Key Biodiversity Areas [KBA], sea turtle nesting sites, cold- and warm-water corals, seamounts, seagrass beds, mangroves, saltmarshes, hydrothermal vents and cold seeps) based on their overlap with Critical Habitat criteria, as defined by IFC. In total, 5798×10³ km² (1.6%) of the analysis area (global ocean plus coastal land strip) were classed as Likely Critical Habitat, and 7526×10³ km² (2.1%) as Potential Critical Habitat; the remainder (96.3%) were Unclassified. The latter was primarily due to the paucity of biodiversity data in marine areas beyond national jurisdiction and/or in deep waters, and the comparatively fewer protected areas and KBAs in these regions. Globally, protected areas constituted 65.9% of the combined Likely and Potential Critical Habitat extent, and KBAs 29.3%, not accounting for the overlap between these two features. Relative Critical Habitat extent in Exclusive Economic Zones varied dramatically between countries. This work is likely to be of particular use for industries operating in the marine and coastal realms as an early screening aid prior to in situ Critical Habitat assessment; to financial institutions making investment decisions; and to those wishing to implement good practice policies relevant to biodiversity management. Supplementary material (available online) includes other global datasets considered, documentation and justification of biodiversity feature classification, detail of IFC PS6 criteria/scenarios, and coverage calculations.     

A margin-wide BSR gas hydrate assessment: Canada’s Atlantic margin

It is the intent of this paper to explore a significant extent of an entire passive continental margin for hydrate occurrence to understand hydrate modes of occurrence, preferred geologic settings and estimate potential volumes of methane. The presence of gas hydrates offshore of eastern Canada has long been inferred from estimated stability zone calculations, but little physical evidence has been offered. An extensive set of 2-D and 3-D, single and multi-channel seismic reflection data comprising in excess of 140,000 line-km was analyzed. Bottom simulating reflections (BSR) were unequivocally identified at seven sites, ranging between 250 and 445 m below the seafloor and in water depths of 620-2850 m. The combined area of the BSRs is 9311 km², which comprises a small proportion of the entire theoretical stability zone along the Canadian Atlantic margin (∼715,165 km²). The BSR within at least six of these sites lies in a sedimentary drift deposit or sediment wave field, indicating the likelihood of grain sorting and potential porosity and permeability (reservoir) development. Although there are a variety of conditions required to generate and recognize a BSR, one might assume that these sites offer the most potential for highest hydrate concentration and exploitation. Total hydrate in formation at the sites of recognized BSR’s is estimated at 17 to 190 × 10⁹ m³ or 0.28 to 3.12 × 10¹³ m³ of methane gas at STP. Although it has been shown that hydrate can exist without a BSR, the results from this regional study argue that conservative estimates of the global reserve of hydrate along continental margins are necessary.     

A Mössbauer spectroscopic and X-ray diffraction study of the iron mineralogy of some sediments from the Southwestern Pacific Basin

The results of a ⁵⁷Fe Mössbauer spectroscopic and X-ray diffraction study of four pelagic clay sediments from the Southwestern Pacific Basin collected at increasing distances from New Zealand, on a New Zealand—Rarotonga transect, are presented. These show that, with increasing distance from New Zealand, the Fe³⁺/Fe²⁺ ratio of the sediment increases as a result of the increasing contribution of the X-ray amorphous secondary hydrous iron oxides, notably ferrihydrite, due to the longer sedimentation periods and consequent greater degree of oxidation of the sediments. This increase in the Fe³⁺/Fe²⁺ ratio is correlated with the change in colour of the sediments from pale yellowish to dusky brown, as well as a number of other sediment parameters. Apart from a slight increase in the relative abundance of montmorillonite with increasing distance from New Zealand, the abundances of the other clay minerals, illite and kaolinite, and of chlorite in the sediments are approximately equal. Quartz and feldspar with minor augite are the dominant detrital minerals. Calcite is present in minor amounts in some of the sediments.     

Australasian asphaltite strandings: Their origin reviewed in light of the effects of weathering and biodegradation on their biomarker and isotopic profiles

Asphaltites, long known to strand along the coastline of southern Australia and as distantly as New Zealand and Macquarie Island, are widely regarded as artefacts of submarine oil seepage. Their remarkably uniform composition suggests a common source: marine shale containing sulphur-rich Type II kerogen, probably deposited during an Early Cretaceous oceanic anoxic event (OAE). Suitable hydrocarbon kitchens may exist in the offshore Bight and Otway basins. The physical character of the asphaltites, including laminations and flow structures, and their degree of alteration, which is not the result of biodegradation or extensive water washing, suggest an origin from subsurface tar mats subsequently exposed by the incision of submarine canyons, with the possible formation of asphaltic volcanoes. API gravities of 4–18° impart quasi-neutral buoyancy, implying many asphaltites were submerged drifters prior to stranding, their degree of weathering reflecting, at least in part, the residence time in the marine environment. For any individual asphaltite specimen, this will depend on the proximity of the seafloor seep to the stranding site, an important consideration when attempting to locate their point of origin.This study investigates the hydrocarbon biomarker signatures and n-alkane δ¹³C profiles of asphaltite specimens from stranding sites on the Eyre Peninsula (n = 2), Kangaroo Island (n = 4) and the Limestone Coast (n = 3), South Australia, and the south island of New Zealand (n = 2). Sub-samples of the interior and weathered surface of each specimen were analysed. No distinction could be made between strandings based on their source-dependent molecular and isotopic signatures, confirming their common origin. Comparison of the interior and exterior sub-samples revealed subtle although consistent differences. Given their degree of degradation and isotopic variance, these Australasian asphaltites seem to be products of low intensity seeps in the Ceduna Sub-basin of the Bight Basin and/or Morum Sub-basin of the Otway Basin.     

The Ryukyu Trench may function as a “depocenter” for anthropogenic marine litter

While concern over anthropogenic marine litter around coastlines is increasing worldwide, information on this litter in trenches on the seafloor is very sparse. We investigated the amount of marine litter on the deep-sea bottom around the Ryukyu Islands in the Northwest Pacific, based on trawl samples. The density of litter observed in the axis of the Ryukyu Trench (7100 m) and in the basin of the Okinawa Trough ranged from 1.2 × 10³ to 7.1 × 10³ items km^?2, or 7.5–121.4 kg km^?2, which was significantly higher than that observed on the adjacent shallower continental slopes or abyssal plain (0.1 × 10³ to 0.6 × 10³ items km^?2; 0.03–9.2 kg km^?2). This suggests that trenches and troughs function as “depocenters” for anthropogenic litter because of their deeper and enclosed topographies.     

Status of the marine protected area network across the English channel (La Manche): Cross-country similarities and differences in MPA designation,management and monitoring

Recent international policy developments require states to conserve at least 10% of coastal and marine areas by creating effectively managed and ecologically coherent networks of protected areas in the marine environment. In the framework of the PANACHE project, the current status of designation, management and monitoring of the network of marine protected areas (MPAs) of an important environmental, social and economic marine area: the English Channel (the Channel) was examined. Currently 224 MPAs exist belonging to 12 different designation categories and covering 17 440 km², or approximately 20.3% of the project area in the Channel. International protection targets in the marine environment are thus met at this regional scale, although the individual contributions of the UK and France are considerably different, with French MPAs accounting for nearly 80% of the total area protected. Differences between countries are also found regarding MPA designation categories (11 in France, 6 in the UK, 1 in the Channel Islands) and management structures (with more actors involved in the UK) and approach, whereas the monitoring techniques used are similar, although more standardised in the UK. Pending challenges include greater within-country and cross-country MPA designation, monitoring and management simplicity, integration and coordination as well as the assessment of management effectiveness and ecological coherence of the Channel network of MPAs.     

Geochemical overview and undiscovered gas resources generated from Hamitabat petroleum system in the Thrace Basin,Turkey

Since the first drill in 1957, three oil, 19 gas and condensate fields have been discovered in the Thrace Basin. However, any petroleum system with its essential elements and processes has not been assigned yet. This study consists of two parts, (1) geochemical overview of the previous work in order to get a necessary help to construct a petroleum system and (2) calculation of quantitative undiscovered hydrocarbon resources generated from this system. An extensive overview study showed that the primary reservoir and source rocks in the Thrace Basin are the Middle Eocene Hamitabat sandstones and shales, respectively, hence it appears that the most effective petroleum system of the Thrace Basin becomes the Hamitabat (!) petroleum system. Currently, 18.5 billion m³ of in-place gas, 2.0 million m³ (12.7 million bbl) in-place waxy oil as well as minor amount of associated condensate were discovered from this system. This study showed that the regional distribution of the oil and gas fields almost overlapped with the previously constructed pod of active Hamitabat shales implying that short and up-dip vertical migration pathway of hydrocarbons from the source to trapping side was available. Thermal model demonstrated that hydrocarbon generation from the Hamitabat shales commenced in the Early Miocene. The amount of quantitative gas generation based on the mean-original TOC = 0.94 wt%, mean-original HI = 217 HC/g TOC and the volume of the pod of active source rock = 49 km³ is approximately 110 billion m³ of gaseous hydrocarbons that results in a high generation–accumulation efficiency of 17% when 18.5 billion m³ of already discovered hydrocarbons are considered.     

From Scotland to New Scotland: Constructing a sectoral marine plan for tidal energy for Nova Scotia

Competing usage of marine space has prompted several coastal nations to implement marine spatial planning (MSP). While progressive governments promote the deployment of renewable energy technologies (RETs) in order to meet renewable energy capacity and greenhouse gas emissions reductions targets, offshore RETs become another player operating within a finite and already stressed marine environment. This paper applies the sectoral MSP process employed by Scotland to the Nova Scotia context in order to draft a MSP for the province's tidal energy sector. Applicable legislation is reviewed in order to establish the regulatory authorities with powers to plan for both the marine development and ecosystem protection agendas. The scoping process identifies suitable resource areas based on the operational parameters of commercially viable tidal current turbines (TCTs), while the sustainability appraisal identifies areas of cultural, industry, ecological, and socioeconomic constraint and exclusion. Plan option areas emanating from the applied methodology demonstrated a 238.345 km² (98.1%) increase in suitable TCT deployment area than the marine renewable energy areas identified in Nova Scotia's Marine Renewable Energy Act which did not undertake such a methodology.     

GLORIA survey of the oceanic-continental transition of the Havre-Taupo back-arc basin

A GLORIA (Geological Long-Range Inclined Asdic) side-scan sonar survey, covering 23,000 km², provides the first complete imagery of an active and contiguous, oceanic to continental back-arc system, namely, the Havre Trough to Taupo Volcanic Zone (TVZ) New Zealand. Havre Trough tectonism and volcanism relates to a series of laterally discontinuous, mutiple spreading rifts which terminate southward at the 3-km-deep Ngatoro Basin. A 45-km sinistral offset attributed toen echelon synthetic shearing separates the basin from the actively spreading TVZ. Sonographs reveal a youthful and complex volcanic seascape with 20 newly discovered seamounts, whereas flanking regions are mantled with a largely featureless mud blanket.