scholarly journals Sediment impacts on sponges and a deep-sea coral in New Zealand

2021 ◽  
Author(s):  
◽  
Valeria Mobilia
Keyword(s):  
New Zealand ◽  
Suspended Sediment ◽  
Deep Sea ◽  
Anthropogenic Disturbance ◽  
Habitat Structure ◽  
Anthropogenic Activities ◽  
Benthic Communities ◽  
Bottom Contact ◽  
Suspended Sediment Concentrations ◽  
Offshore Activities

<p><b>Increased levels of suspended sediment in the water column are important factors contributing to the degradation of marine ecosystems worldwide. In coastal waters, temporal variation in suspended sediment concentrations (SSCs) occurs naturally due to seasonal and oceanographic processes. However, there is evidence that anthropogenic activities are increasing sediment concentrations. The volume of sediment moving from land-based sources into coastal ecosystems and human activities in the ocean disturbing the seafloor, such as dredging and bottom-contact fisheries, have been increasing over the last century. In addition, offshore activities, particularly bottom-contact fishing and potential deep-sea mining, can create sediment plumes in the deep-sea that may extend over long distances. Elevated suspended sediment concentrations have detrimental effects on benthic communities, particularly for suspension feeders like sponges and corals.</b></p> <p>The aim of this thesis was to investigate the effects of increased SSCs that might arise from heavy anthropogenic disturbance on common shallow water and deep-sea sponges and a deep-sea coral in New Zealand, as these groups contribute to habitat structure in some benthic environments, including the deep sea.</p>

scholarly journals Sediment impacts on sponges and a deep-sea coral in New Zealand

2021 ◽  
Author(s):  
◽  
Valeria Mobilia
Keyword(s):  
New Zealand ◽  
Suspended Sediment ◽  
Deep Sea ◽  
Anthropogenic Disturbance ◽  
Habitat Structure ◽  
Anthropogenic Activities ◽  
Benthic Communities ◽  
Bottom Contact ◽  
Suspended Sediment Concentrations ◽  
Offshore Activities

<p><b>Increased levels of suspended sediment in the water column are important factors contributing to the degradation of marine ecosystems worldwide. In coastal waters, temporal variation in suspended sediment concentrations (SSCs) occurs naturally due to seasonal and oceanographic processes. However, there is evidence that anthropogenic activities are increasing sediment concentrations. The volume of sediment moving from land-based sources into coastal ecosystems and human activities in the ocean disturbing the seafloor, such as dredging and bottom-contact fisheries, have been increasing over the last century. In addition, offshore activities, particularly bottom-contact fishing and potential deep-sea mining, can create sediment plumes in the deep-sea that may extend over long distances. Elevated suspended sediment concentrations have detrimental effects on benthic communities, particularly for suspension feeders like sponges and corals.</b></p> <p>The aim of this thesis was to investigate the effects of increased SSCs that might arise from heavy anthropogenic disturbance on common shallow water and deep-sea sponges and a deep-sea coral in New Zealand, as these groups contribute to habitat structure in some benthic environments, including the deep sea.</p>

scholarly journals Differences in meiofauna communities with sediment depth are greater than habitat effects on the New Zealand continental margin: implications for vulnerability to anthropogenic disturbance

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2154 ◽  
Author(s):  
Norliana Rosli ◽  
Daniel Leduc ◽  
Ashley A. Rowden ◽  
Malcolm R. Clark ◽  
P. Keith Probert ◽  
...  
Keyword(s):  
Community Structure ◽  
New Zealand ◽  
Deep Sea ◽  
Anthropogenic Activities ◽  
Benthic Communities ◽  
Regional Scale ◽  
Sediment Surface ◽  
Small Scale ◽  
Sediment Layer ◽  
Meiofaunal Community

Studies of deep-sea benthic communities have largely focused on particular (macro) habitats in isolation, with few studies considering multiple habitats simultaneously in a comparable manner. Compared to mega-epifauna and macrofauna, much less is known about habitat-related variation in meiofaunal community attributes (abundance, diversity and community structure). Here, we investigated meiofaunal community attributes in slope, canyon, seamount, and seep habitats in two regions on the continental slope of New Zealand (Hikurangi Margin and Bay of Plenty) at four water depths (700, 1,000, 1,200 and 1,500 m). We found that patterns were not the same for each community attribute. Significant differences in abundance were consistent across regions, habitats, water and sediment depths, while diversity and community structure only differed between sediment depths. Abundance was higher in canyon and seep habitats compared with other habitats, while between sediment layer, abundance and diversity were higher at the sediment surface. Our findings suggest that meiofaunal community attributes are affected by environmental factors that operate on micro- (cm) to meso- (0.1–10 km), and regional scales (> 100 km). We also found a weak, but significant, correlation between trawling intensity and surface sediment diversity. Overall, our results indicate that variability in meiofaunal communities was greater at small scale than at habitat or regional scale. These findings provide new insights into the factors controlling meiofauna in these deep-sea habitats and their potential vulnerability to anthropogenic activities.

scholarly journals Simulated mining-related sedimentation impacts on the deep-sea macrofauna of the Chatham Rise, New Zealand

2021 ◽  
Author(s):  
Campbell Murray
Keyword(s):  
Community Structure ◽  
New Zealand ◽  
Deep Sea ◽  
Benthic Communities ◽  
Sampling Period ◽  
Mining Area ◽  
Warning Sign ◽  
Disturbed Areas ◽  
One Year ◽  
The Impact

<p>With the possibility of deep-sea mining of marine mineral resources occurring in the near future, it is necessary to understand the potential impacts that mining may have on benthic communities. Previous simulated mining experiments have observed direct impacts of deep-sea mining (e.g., faunal mortality); however, indirect impacts of sedimentation were not understood. In New Zealand, there has been interest in mining the seabed of the Chatham Rise, but mining consents have been refused, partly due to the uncertainties of sedimentation impacts on benthic communities. A disturbance experiment conducted in 2019 on the Rise used a modified agricultural plough designed to create a sediment cloud that could result from mining. This disturbance was used to assess the resilience of benthic communities to sedimentation in a proposed future mining area. Macrofaunal and sediment samples were collected with a multicorer before, immediately after and one year after disturbance to assess the impact on the community and its ability to recover. Samplingevents took place in disturbed (physically run over by the plough and subjected to sedimentation) and undisturbed areas (subjected to sedimentation only) at each sampling period. Macrofaunal abundance significantly decreased in disturbed areas after disturbancebut not in undisturbed areas. However, community structure changed in both areas after disturbance; in disturbed areas this was mostly driven by changes in numerically dominant fauna, but in undisturbed areas by the more sensitive fauna which may provide an early warning sign for further changes under increased sedimentation. One year after disturbance, community structure had recovered in both areas. Abundance-based community structure correlated most strongly with C:N molar ratios in the sediment which increased after disturbance. Ecosystem function was measured by sediment community oxygen consumption (SCOC) which increased similarly in both disturbed and undisturbed areas after disturbance; SCOC may be a more sensitive measure than community structure in assessing sedimentation impacts. No correlations were found between SCOC and macrofaunal abundance, biomass, diversity or bacterial abundance. The results of this research are useful for managing the impacts of industries where sedimentation is an issue, such as for bottom trawl fisheries and deep-sea mining. The results highlight the importance of leaving unmined patches of seabed adjacent to or within mined areas, to aid the recovery of macrofaunal communities subjected to mining disturbance.</p>

scholarly journals Review and syntheses: Impacts of turbidity flows on deep-sea benthic communities

2021 ◽  
Vol 18 (5) ◽  
pp. 1893-1908
Author(s):  
Katharine T. Bigham ◽  
Ashley A. Rowden ◽  
Daniel Leduc ◽  
David A. Bowden
Keyword(s):  
New Zealand ◽  
Deep Sea ◽  
Benthic Community ◽  
Large Scale ◽  
Benthic Communities ◽  
Clear Cut ◽  
Local Diversity ◽  
Physical Chemical ◽  
Pulse Type ◽  
Diversity Studies

Abstract. Turbidity flows – underwater avalanches – are large-scale physical disturbances that are believed to have profound and lasting impacts on benthic communities in the deep sea, with hypothesized effects on both productivity and diversity. In this review we summarize the physical characteristics of turbidity flows and the mechanisms by which they influence deep-sea benthic communities, both as an immediate pulse-type disturbance and through longer-term press-type impacts. Further, we use data from turbidity flows that occurred hundreds to thousands of years ago as well as three more recent events to assess published hypotheses that turbidity flows affect productivity and diversity. We find, unlike previous reviews, that evidence for changes in productivity in the studies was ambiguous at best, whereas the influence on regional and local diversity was more clear-cut: as had previously been hypothesized, turbidity flows decrease local diversity but create mosaics of habitat patches that contribute to increased regional diversity. Studies of more recent turbidity flows provide greater insights into their impacts in the deep sea, but without pre-disturbance data, the factors that drive patterns in benthic community productivity and diversity, be they physical, chemical, or a combination thereof, still cannot be identified. We propose criteria for data that would be necessary for testing these hypotheses and suggest that studies of Kaikōura Canyon, New Zealand, where an earthquake-triggered turbidity flow occurred in 2016, will provide insights into the impacts of turbidity flows on deep-sea benthic communities as well as the impacts of other large-scale disturbances such as deep-sea mining.

scholarly journals Review and syntheses: Turbidity flows – evidence for effects on deep-sea benthic community productivity is ambiguous but the influence on diversity is clearer

2020 ◽  
Author(s):  
Katharine T. Bigham ◽  
Ashley A. Rowden ◽  
Daniel Leduc ◽  
David A. Bowden
Keyword(s):  
New Zealand ◽  
Deep Sea ◽  
Benthic Community ◽  
Large Scale ◽  
Benthic Communities ◽  
Clear Cut ◽  
Local Diversity ◽  
Physical Chemical ◽  
Pulse Type ◽  
Diversity Studies

Abstract. Turbidity flows – underwater avalanches – are large-scale physical disturbances that are believed to have profound and lasting impacts on benthic communities in the deep sea, with hypothesised effects on both productivity and diversity. In this review we summarize the physical characteristics of turbidity flows and the mechanisms by which they influence deep sea benthic communities, both as an immediate pulse-type disturbance and through longer term press-type impacts. Further, we use data from turbidity flows that occurred hundreds to thousands of years ago as well as three more recent events to assess published hypotheses that turbidity flows affect productivity and diversity. We found, unlike previous reviews, that evidence for changes in productivity in the studies was ambiguous at best, whereas the influence on regional and local diversity was more clear-cut: as had previously been hypothesized turbidity flows decrease local diversity but create mosaics of habitat patches that contribute to increased regional diversity. Studies of more recent turbidity flows provide greater insights into their impacts in the deep sea but without pre-disturbance data the factors that drive patterns in benthic community productivity and diversity, be they physical, chemical, or a combination thereof, still cannot be identified. We propose criteria for data that would be necessary for testing these hypotheses and suggest that studies of Kaikōura Canyon, New Zealand, where an earthquake-triggered turbidity flow occurred in 2016, will present helpful insights into the impacts of turbidity flows on deep-sea benthic communities.

scholarly journals Effects of mangrove removal on benthic communities and sediment characteristics at Mangawhai Harbour, northern New Zealand

2010 ◽  
Vol 67 (6) ◽  
pp. 1087-1104 ◽  
Author(s):  
Andrea C. Alfaro
Keyword(s):  
New Zealand ◽  
Anthropogenic Disturbance ◽  
Forest Decline ◽  
Benthic Communities ◽  
Organic Content ◽  
Sediment Characteristics ◽  
Subsequent Increase ◽  
Before And After ◽  
Faunal Density ◽  
The Tropics

Abstract Alfaro, A. C. 2010. Effects of mangrove removal on benthic communities and sediment characteristics at Mangawhai Harbour, northern New Zealand. – ICES Journal of Marine Science, 67: 1087–1104. The spread of mangroves at many locations in temperate northern New Zealand provides a stark contrast to the well-documented trend in mangrove forest decline recorded through the tropics and subtropics. To explore this difference, improved understanding is needed of New Zealand's mangrove ecosystems and how they respond to anthropogenic disturbance. The effect of mangrove removal on the community ecology of mangrove stands and adjacent habitats was investigated within Mangawhai Estuary, northern New Zealand, between March 2004 and September 2006. The vegetation, benthic macrofauna, and sediments were sampled within habitats (marshgrass, mangrove stands, pneumatophore zones, sandflats, and channels) at a treatment site (mangroves removed) and two undisturbed sites, before and after mangrove-removal activities. Mature mangrove habitats had less total abundance and fewer taxa than all the other habitats sampled and were dominated by pulmonate snails (Amphibola crenata) and mud crabs (Helice crassa). Whereas faunal composition varied seasonally as a result of life-history dynamics, temporal changes could be attributed to mangrove-removal activities. Mangrove eradication was followed by immediate changes in the sediment from a muddy to sandier environment, which favoured an overall increase in the abundance of crabs, snails, and bivalves. However, unexpected topographic catchment reconfigurations in late 2005 may have caused a subsequent increase in the delivery of silt and organic content to the study area and an overall decrease in faunal density in March and September 2006. The study provides direct evidence of the effect of mangroves on sediment and benthic faunal characteristics and the importance of catchment-derived imports to estuarine ecosystems.

Limited differences among habitats in deep-sea macro-infaunal communities off New Zealand: implications for their vulnerability to anthropogenic disturbance

2016 ◽  
Vol 37 (4) ◽  
pp. 845-866 ◽  
Author(s):  
Daniel Leduc ◽  
Ashley A. Rowden ◽  
Malcolm R. Clark ◽  
David A. Bowden ◽  
Andrew R. Thurber
Keyword(s):  
New Zealand ◽  
Deep Sea ◽  
Anthropogenic Disturbance

scholarly journals Simulated mining-related sedimentation impacts on the deep-sea macrofauna of the Chatham Rise, New Zealand

2021 ◽  
Author(s):  
Campbell Murray
Keyword(s):  
Community Structure ◽  
New Zealand ◽  
Deep Sea ◽  
Benthic Communities ◽  
Sampling Period ◽  
Mining Area ◽  
Warning Sign ◽  
Disturbed Areas ◽  
One Year ◽  
The Impact

<p>With the possibility of deep-sea mining of marine mineral resources occurring in the near future, it is necessary to understand the potential impacts that mining may have on benthic communities. Previous simulated mining experiments have observed direct impacts of deep-sea mining (e.g., faunal mortality); however, indirect impacts of sedimentation were not understood. In New Zealand, there has been interest in mining the seabed of the Chatham Rise, but mining consents have been refused, partly due to the uncertainties of sedimentation impacts on benthic communities. A disturbance experiment conducted in 2019 on the Rise used a modified agricultural plough designed to create a sediment cloud that could result from mining. This disturbance was used to assess the resilience of benthic communities to sedimentation in a proposed future mining area. Macrofaunal and sediment samples were collected with a multicorer before, immediately after and one year after disturbance to assess the impact on the community and its ability to recover. Samplingevents took place in disturbed (physically run over by the plough and subjected to sedimentation) and undisturbed areas (subjected to sedimentation only) at each sampling period. Macrofaunal abundance significantly decreased in disturbed areas after disturbancebut not in undisturbed areas. However, community structure changed in both areas after disturbance; in disturbed areas this was mostly driven by changes in numerically dominant fauna, but in undisturbed areas by the more sensitive fauna which may provide an early warning sign for further changes under increased sedimentation. One year after disturbance, community structure had recovered in both areas. Abundance-based community structure correlated most strongly with C:N molar ratios in the sediment which increased after disturbance. Ecosystem function was measured by sediment community oxygen consumption (SCOC) which increased similarly in both disturbed and undisturbed areas after disturbance; SCOC may be a more sensitive measure than community structure in assessing sedimentation impacts. No correlations were found between SCOC and macrofaunal abundance, biomass, diversity or bacterial abundance. The results of this research are useful for managing the impacts of industries where sedimentation is an issue, such as for bottom trawl fisheries and deep-sea mining. The results highlight the importance of leaving unmined patches of seabed adjacent to or within mined areas, to aid the recovery of macrofaunal communities subjected to mining disturbance.</p>

scholarly journals Insights on the Impacts of Hydroclimatic Extremes and Anthropogenic Activities on Sediment Yield of a River Basin

Earth ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 32-50
Author(s):  
Rocky Talchabhadel ◽  
Jeeban Panthi ◽  
Sanjib Sharma ◽  
Ganesh R. Ghimire ◽  
Rupesh Baniya ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
River Basin ◽  
Extreme Precipitation ◽  
Suspended Sediment Concentration ◽  
Anthropogenic Activities ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Mountain River ◽  
Ecological Processes ◽  
Precipitation Indices

Streamflow and sediment flux variations in a mountain river basin directly affect the downstream biodiversity and ecological processes. Precipitation is expected to be one of the main drivers of these variations in the Himalayas. However, such relations have not been explored for the mountain river basin, Nepal. This paper explores the variation in streamflow and sediment flux from 2006 to 2019 in central Nepal’s Kali Gandaki River basin and correlates them to precipitation indices computed from 77 stations across the basin. Nine precipitation indices and four other ratio-based indices are used for comparison. Percentage contributions of maximum 1-day, consecutive 3-day, 5-day and 7-day precipitation to the annual precipitation provide information on the severity of precipitation extremeness. We found that maximum suspended sediment concentration had a significant positive correlation with the maximum consecutive 3-day precipitation. In contrast, average suspended sediment concentration had significant positive correlations with all ratio-based precipitation indices. The existing sediment erosion trend, driven by the amount, intensity, and frequency of extreme precipitation, demands urgency in sediment source management on the Nepal Himalaya’s mountain slopes. The increment in extreme sediment transports partially resulted from anthropogenic interventions, especially landslides triggered by poorly-constructed roads, and the changing nature of extreme precipitation driven by climate variability.

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