1 CRUISE REPORT S-256: GLOBAL OCEAN SCIENTIFIC ACTIVITIES UNDERTAKEN ABOARD THE SSV ROBERT C. SEAMANS Auckland, New Zealand – Wellington, New Zealand – Dunedin, New Zealand – Lyttelton, New Zealand – Wellington, New Zealand 14 November – 23 December, 2014 Sea Education Association Woods Hole, Massachusetts
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CRUISE REPORT
S-256: GLOBAL OCEAN
SCIENTIFIC ACTIVITIES UNDERTAKEN ABOARD THE SSV ROBERT C. SEAMANS
Auckland, New Zealand – Wellington, New Zealand – Dunedin, New Zealand – Lyttelton, New Zealand – Wellington, New Zealand
14 November – 23 December, 2014
Sea Education Association Woods Hole, Massachusetts
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Citation: Goodwin, D.S., 2014. Final Report for S.E.A. Cruise S256. Sea Education Association, Woods Hole, MA 02543, USA. www.sea.edu. To obtain unpublished data, contact the SEA Data Archivist: Dr. Erik Zettler Sea Education Association P.O. Box 6 Woods Hole, MA 02543 508-540-3954 or 800-552-3633 (phone) 508-457-4673 (fax) [email protected] (email) www.sea.edu (website)
Table 2: Summary of oceanographic sampling stations 12
Table 3: Hydrocast station data 14
Table 4: Surface station data 20
Table 5a: Neuston tow hydrographic data 22
Table 5b: Neuston tow biological data 24
Table 6a: Meter net hydrographic data 25
Table 6b: Meter net biological data 26
Table 7a: Zooplankton 100 count data 27
Table 7b: Zooplankton 100 count data (continued) 29
Table 8: Phytoplankton net data 31
Table 9: Shipek grab data 32
Table 10: Student research projects 33
Student Research Project Abstracts 34
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Table 1: S256 Ship's Company, SSV Robert C. Seamans Nautical Staff & Faculty Rick Miller Captain Dan Stone Chief Mate Johnny O’Keefe Second Mate Ashley Meyer Third Mate Ted Fleming Chief Engineer Ben Ahlvin Assistant Engineer Vickie Leavitt Steward Sarianna Crook Deckhand Jason Mancini Maritime History Faculty Scientific Staff Deb Goodwin Chief Scientist Julia Twichell First Assistant Scientist Kelsey Lane Second Assistant Scientist Laura Cooney Third Assistant Scientist Students Anna Bute University of Washington Allisa Dalpe Connecticut College Sam Gartzman Beloit College Laina Gray Canisius College Briana Grenier University of Rhode Island Kate Hruby University of New England Ali Johnson Stonehill College Becky Konijnenberg Amherst College Marine Lebrec University of Washington Roshni Mangar College of the Atlantic Christopher Marshall SUNY School of Environmental Science & Forestry Kristin McDonald Middlebury College Nick Metesanz Grinnell College Kate Morneault Stonehill College Kate Perkins Washington State University Heather Piekarz Hamilton College Kendall Reinhart Dartmouth College Kylie Sehrer Oregon State University Eli Steiker-Ginzberg Oberlin College Devon Tibbils Paul Smith’s College Karissa Vincent Wheaton College Nina Whittaker Kenyon College Kella Woodard University of Massachusetts, Amherst
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Data Description During the S256 six-week passage around New Zealand’s North and South Islands (Figure 1), SSV Robert C. Seamans and her crew explored the subtropical, transitional and subpolar marine environments of the region. Conditions were moderate near Auckland, the Hauraki Gulf and the Bay of Islands on the east side of the North Island; oceanographically, these waters originate in the tropics and subtropics, showing similarities to other Pacific gyres. A major current coming from Australia splits at Cape Reinga (the northern tip of the North Island), and we followed those waters south to Cook Strait and through the narrow passage between islands. Immediately south of Wellington, conditions (and waters) shifted as influences of the Southern Ocean weather and circulation are ever-present. Temperatures cooled dramatically as we sailed south, crossing the Subtropical Front over the Chatham Rise and entering subpolar waters. Moving frequently between the continental shelf and deep offshore waters, we observed major regional and local differences in water chemistry, zooplankton community, and seabird/megafauna presence and assemblage. Four port stops were dedicated to learning about the relationships New Zealand residents have developed with their local marine environment as well as exploring resource management and protection efforts and learning about Maori culture. Oceanographic data were collected along the entirety of the cruise track during 38 stations comprised of 123 individual deployments (summarized in Table 2; detailed in Tables 3 - 9) as well as related chemical analyses for nutrients, extracted chlorophyll, seawater pH and alkalinity (Tables 3 and 4). Furthermore, continuous surface water measurements (sea surface temperature, salinity, in vivo chlorophyll fluorescence, CDOM fluorescence and transmissivity by the ship's flow-through system; Figure 2), water depth and sub-bottom profiles (CHIRP system), upper ocean currents (ADCP; Figure 3), and meteorological data were gathered. CTD casts with additional complementary instrumentation obtained vertical water column profiles of temperature, salinity, chlorophyll fluorescence and dissolved oxygen (Figure 5). Lengthy CTD, CHIRP, ADCP and flow-through data are not fully presented here; all unpublished data can be made available by arrangement with the SEA Data Archivist (contact information, p. 2). Data supported both ongoing SEA research projects and a diverse suite of student-designed investigations (Table 10 and abstracts p. 34). Research topics included: impacts of ocean acidification on water chemistry, pCO2 flux and pteropods; phytoplankton, zooplankton and gelatinous organism abundance and biodiversity; copepod morphological factors in diel vertical migration; wave energy potential; assessment of near-coastal ocean circulation patterns; sediment transport processes; and evaluation of the state of the New Zealand marine environment using metrics from the Ocean Health Index. The resulting student manuscripts are available upon request from Deb Goodwin, S256 Chief Scientist.
Figure 1. Final cruise track for S256 based on hourly (local time) positions. The voyage began in Auckland, had port stops in Wellington, Dunedin and Lyttelton, and concluded in Wellington, New Zealand.
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Figure 2a. Surface water temperature (°C), salinity (psu), chlorophyll fluorescence (volts) and CDOM fluorescence (volts) for S256 as measured by flow through system sensors.
The ship’s flow through system sensors included a SeaBird Thermosalinograph (S/N 0035), WETLabs C-Star CDOM fluorometer (S/N WSCD-1257), and Turner Designs Model 10-AU in vivo chlorophyll-a fluorometer (S/N 6467-RTX).
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Figure 2b. Surface water nitrate concentration (uM), phosphate concentration (uM), chlorophyll concentration (0.45um; ug/L), and pH for S256 as measured by laboratory analyses on discrete surface station water samples.
Extracted chlorophyll-a samples were filtered through 0.45 µm filters and measured with a Turner Designs Model 10-AU fluorometer. Seawater pH was determined using m-cresol purple indicator dye and spectrophotometry. Nutrients (PO4 and NO3) were assessed with colorometric spectrophotometry.
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Figure 3. Surface current vectors (mm/s) for the S256 cruise track (left: North Island; right: South Island). Note that 500 mm/s is approximately 1.0 knot.
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Figure 4: Wind speed and direction for the S256 cruise track, as measured by the ship’s anemometer. Note that 500 mm/s is approximately 1.0 knot.
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Figure 5a: Hydrographic along-track sections for S256. Oceanographic regions indicated below density section apply to all plots.
Data gathered during hydrocast stations utilizing a SeaBird 19PlusV2 CTD (S/N 4043).
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Figure 5b: Hydrographic along-track sections for S256. Oceanographic regions indicated below Chlorophyll section apply to all plots; note varied depth axis scales.
Data gathered during hydrocast stations utilizing Seapoint Chlorophyll fluorometer (S/N SCF-3149) and SeaBird Dissolved Oxygen sensor (model 43; S/N 1518).
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Table 2: Summary of oceanographic sampling stations for S256. Station
Number (S256-)
Date Time (Local)
Log (nm)
Latitude (deg S)
Longitude (deg E) NT MN PN HC SG Surface
Station General Locale
001 18-Nov-14 1025 21.8 -36.60 174.98 X X X Hauraki Gulf 002 19-Nov-14 0002 94.8 -35.40 174.91 X 001 NE Shelf 003 19-Nov-14 1020 164.4 -34.75 173.94 X X X X NE Shelf 004 19-Nov-14 2228 221.4 -34.82 173.28 X X XXX 002 NE Shelf 005 20-Nov-14 1001 265.7 -34.17 172.85 X X X NE Shelf 006 21-Nov-14 0018 NA -34.69 172.45 X 003 NW Shelf 007 21-Nov-14 1016 NA -35.56 172.62 X X X NW Shelf 008 21-Nov-14 2246 493.0 -36.58 172.78 X X 004 NW Shelf 009 22-Nov-14 1022 544.0 -37.30 172.96 X X X NW Shelf 010 23-Nov-14 0953 640.0 -38.73 173.31 X X X X NW Shelf 011 24-Nov-14 0018 703.0 -39.69 173.11 X 006 NW Shelf 012 24-Nov-14 1016 740.0 -39.96 173.54 X X X NW Shelf 013 25-Nov-14 1000 887.0 -41.45 174.43 X X X Cook Strait 014 30-Nov-14 1210 937.0 -41.26 174.89 X XXX Wellington Harbor 015 30-Nov-14 2243 985.0 -41.86 174.33 X X 012 Otago Shelf 016 1-Dec-14 1023 1041.0 -42.42 174.03 X X X Otago Shelf 017 2-Dec-14 0005 1099.0 -41.69 173.69 X 013 Chatham Rise 018 2-Dec-14 1011 1044.0 -42.97 173.51 X X X Otago Shelf 019 3-Dec-14 0009 1191.0 -43.23 173.45 X 014 Otago Shelf 020 3-Dec-14 1031 1255.0 -44.23 173.41 X X X X Chatham Rise 021 4-Dec-14 0007 1313.0 -44.83 172.74 X 015 Chatham Rise 022 4-Dec-14 1028 1360.0 -45.13 171.83 X X X Chatham Rise 023 5-Dec-14 0018 1423.0 -44.73 172.00 X 016 Otago Shelf 024 5-Dec-14 1106 1489.0 -44.34 173.27 X X X Otago Shelf 025 6-Dec-14 0055 1541.0 -44.57 173.22 X 017 Chatham Rise 026 6-Dec-14 1031 1586.0 -44.95 172.42 X X X Subpolar Waters 027 12-Dec-14 0026 1742.0 -45.93 171.23 X 024 Subpolar Waters 028 12-Dec-14 1015 1786.0 -45.50 171.35 X X X Otago Shelf 029 12-Dec-14 2044 1820.0 -44.97 171.24 X XXX Otago Shelf 030 13-Dec-14 0033 1837.0 -44.93 171.56 X 025 Otago Shelf 031 13-Dec-14 1035 1899.0 -44.29 172.48 X 026 Otago Shelf 032 14-Dec-14 0227 1980.0 -43.35 173.52 X X 027 Otago Shelf 033 14-Dec-14 1107 2025.0 -43.40 172.98 X 028 Otago Shelf 034 18-Dec-14 1136 2064.0 -43.41 173.03 X 034 Otago Shelf
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Table 2: Summary of oceanographic sampling stations for S256 (continued).
Station Number (S256-)
Date Time (Local)
Log (nm)
Latitude (deg S)
Longitude (deg E) NT MN PN HC/
CTD SG Surface Station General Locale
035 19-Dec-14 0002 2128.0 -42.41 174.05 X 035 Otago Shelf 036 19-Dec-14 0920 2182.0 -42.17 175.13 X X Cook Strait 037 19-Dec-14 2230 2222.0 -42.12 175.69 X X 036 East Shelf 038 20-Dec-14 1133 2276.0 -41.71 175.88 X 037 East Shelf Notes: Station 036 was the styrocast with accompanying deep free CTD and vertical MN. At station 026 the 2MN was deployed. The taffrail log was lost between stations 005 and 006; thereafter, values from the ship’s electronic log are reported. Surface station data are in Table 4. In Table 2, abbreviations for oceanographic equipment deployed are: NT – neuston tow; MN – 1 meter net (oblique tow); PN – phytoplankton net; HC – hydrocast with 12 Niskin bottles, CTD and optical instrumentation; CTD – free CTD with no ancillary instrumentation; SG – shipek grab. General Locales are categorized by traditional oceanic biomes.
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Table 3: Hydrocast station data for S256. Station locations as in Table 2. Station
All hydrocasts gathered data from a SeaBird 19PlusV2 CTD (S/N 4043) and three auxiliary instruments (Seapoint Chlorophyll fluorometer (S/N SCF-3149), SeaBird Dissolved Oxygen sensor (model 43; S/N 1518), and Biospherical Instruments/SeaBird PAR sensor (S/N 4179)). Extracted chlorophyll-a samples were filtered through 0.45 µm filters and measured with a Turner Designs Model 10-AU fluorometer. Seawater pH was determined using m-cresol purple indicator dye and spectrophotometry. Nutrients (PO4 and NO3) were assessed with colorometric spectrophotometry. Alkalinity was measured by Gran titration. A blank space indicates that no sample was collected for that analysis.
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Table 4: Surface station data for S256. Station locations as in Table 2. Station
The ship’s flow through system sensors included a SeaBird Thermosalinograph (S/N 0035). Extracted chlorophyll-a samples were filtered through 0.45 µm filters and measured with a Turner Designs Model 10-AU fluorometer. Seawater pH was determined using m-cresol purple indicator dye and spectrophotometry. Alkalinity was measured through Gran titration. Nutrients (PO4 and NO3) were assessed with colorometric spectrophotometry. Microplastics were collected by bucket, consolidated on a 20um filter, and enumerated using a dissecting microscope; all particles in this category are less than 333um in size.
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Table 5a: Neuston tow hydrographic data for S256. Station locations as in Table 2. Station
Moon phase indicates either risen (R) or set (S). Tow area calculated using distance (meters) between successive minutes' GPS positions. Neuston net opening 1.0m wide by 0.5m tall, with a 333µm mesh net. Zooplankton density recorded as wet volume displacement per tow area (ml/m2).
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Table 5b: Neuston tow biological data for S256 (continued). Station locations as in Table 2. Station
Eel larvae (leptocephali), spiny lobster larvae (phyllosoma), marine water striders (halobates) and Lantern fish (myctophids) sorted from net contents and counted. Micronekton and gelatinous micronekton removed using a 333 um mesh sieve; biovolume (ml) recorded. Qualitative descriptions of micronekton removed from zooplankton biomass are available. Floating plastic and tar removed from net contents, sorted and recorded as numbers collected per tow.
Table 6a: Meter net hydrographic data for S256. Station locations as in Table 2. Station
All tows used a 1m net (0.785m2) with 333µm mesh except station 026, which used the 2m net (2.49 m2) with 1000µm mesh. Tow length calculated using distance between successive minutes' GPS positions; tow volume from tow length and net area. Zooplankton density recorded as wet volume displacement per tow volume (ml/m3). During station 036, the MN was attached to the styrocast and therefore drifted only.
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Table 6b: Meter net biological data for S256 (continued). Station locations as in Table 2. Station
029-PN 12-Dec-14 2051 13.6 4.67 33.74 Otago Shelf Drifted NA NA NA NA
Notes: Samples 001 and 029 were lost before analysis; sample 013 contained no phytoplankton. Abbreviations for phytoplankton categories in Table 7: Rh – Rhizosalenia, Ps – Pseudonitzchia, Co – Coscinodiscus, Gy – Gymnodinium, Sk – Skeletonema, Fr – Fragillaria, Ch – Chaetoceros, Bd – Bidulphia, Th – Thalassionema, Ce – Ceratium, Di – Dinophysis, Pr – Protoperidinium, Uk – Unknown. Roman numerals indicate number of different species observed in each genus.
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Table 9: Shipek grab data for S256. Station locations as in Table 2.
Station Number (S256-)
Date Time (Local)
Sea Surface Temperature
(°C)
Chlorophyll Fluorescence
(volts)
Salinity (psu) Location
Seafloor Depth
(m)
Dominant Sediment Type(s) & Size Class
004-SGA 19-Nov-14 2228 15.9 7.21 35.140 Rangaunu Bay Northeast Shelf
004-SGB 19-Nov-14 2334 16.0 6.81 35.234 Rangaunu Bay Northeast Shelf
5.47 nm from river mouth 42
500 – 2000um, rounded quartz sand, shells
<63um, clays
004-SGC 20-Nov-14 0015 16.2 6.74 35.340 Rangaunu Bay Northeast Shelf
6.92 nm from river mouth 43 500 – 2000um, rounded quartz
sand
014-SGA 30-Nov-14 1210 15.6 6.24 34.280 Hutt River
Wellington Harbor 1.21 nm from river mouth
31 <63um, muds
014-SGB 30-Nov-14 1239 15.6 5.83 34.390 Hutt River
Wellington Harbor 1.78 nm from river mouth
34 <63um, muds
014-SGC 30-Nov-14 1305 15.6 6.99 34.422 Hutt River
Wellington Harbor 2.41 nm from river mouth
30 <63um, muds
029-SGA 12-Dec-14 2044 13.6 4.56 33.720 Waitaki River Otago Shelf
4.17 nm from river mouth 24 >2000um, pebbles & stones
029-SGB 12-Dec-14 2112 13.4 4.76 34.101 Waitaki River Otago Shelf
5.36 nm from river mouth 27 >2000um, pebbles
029-SGC 12-Dec-14 2145 13.1 4.82 34.236 Waitaki River Otago Shelf
7.22 nm from river mouth 38 >2000um, pebbles
500 – 2000um, angular sands
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Table 10: Student Research Projects for S256
Geographic distribution and biodiversity of phytoplankton, zooplankton and gelatinous organisms around New Zealand
Roshni Mangar, Nick Metesanz and Kylie Sehrer
The influences of morphological factors on marine copepod diel vertical migration in the waters of New Zealand
Becky Konijnenberg and Christopher Marshall
Shell dissolution in pteropods around the coast of New Zealand Heather Piekarz and Devon Tibbils
Quantifying ocean currents around New Zealand Allisa Dalpe and Ali Johnson
Carbon dioxide fluxes in New Zealand waters Sam Gartzman
Exploring the potential for wave energy and combined wave-wind energy devices off the coast of New Zealand Kristin McDonald
The spatial distribution of micro- and macroplastics in New Zealand waters
Anna Bute, Marine Lebrec and Kate Perkins
Assessing sediment transport from rivers to the ocean through relative calcium carbonate levels, transport systems and
phytoplankton diversity in seafloor sediments
Briana Grenier, Kate Hruby and Karissa Vincent
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Student Research Project Abstracts Geographic distribution and biodiversity of phytoplankton, zooplankton and gelatinous organisms around New Zealand – Roshni Mangar, Nick Metesanz and Kylie Sehrer The purpose of this study was to explore the biogeography of phytoplankton, zooplankton, and gelatinous organisms in the water masses surrounding New Zealand. Water masses were delineated using temperature and salinity variations analyzed from a continuous water flow through system. Organism samples were obtained through a variety of net tows that were analyzed for diversity, abundance and biomass. Chlorophyll-a levels showed significant differences among water masses, implying the presence of discrete phytoplankton communities. Dinoflagellate diversity correlated strongly with phytoplankton biomass, implying a link between biomass and biodiversity with implications for overall ocean health and trophic system structure. Zooplankton diversity and dominant groups were found to be significantly different across water masses. Copepods were present in all water masses. The greatest diversity of zooplankton was in the SubTropical Front, confirming the hypothesis that this water mass has the greatest diversity due to the different converging currents. Gelatinous organisms varied in abundance and type between water masses, supporting the hypothesis that gelatinous organisms have specific temperature and salinity tolerances based on type. Additionally, a positive relationship was found to exist between zooplankton diversity and gelatinous variation. Our findings help further define the spatial organization of a variety of trophic levels within the waters surrounding New Zealand. The influences of morphological factors on marine copepod diel vertical migration in the waters of New Zealand – Becky Konijnenberg and Christopher Marshall Copepods exhibit diel vertical migration (DVM) in both freshwater and saltwater habitats, making it a popular field of research because this movement is one of the largest organismal migrations in the world. This report focuses upon morphological differences between copepods at various depths as well as times within the water column in New Zealand’s coastal waters in order to assess the presence of vertical migration in these waters. The morphological characteristics sampled for include size (mm), shape category, and color pigmentation. Based on the resulting data, size is the most determining morphological trait expressed in DVM patterns. Smaller copepods tend to remain at depth during the day as compared to a more equal distribution during the night. In comparison, shape and pigmentation do not exhibit variability in the water column, or between night and day. Shell dissolution in pteropods around the coast of New Zealand – Heather Piekarz and Devon Tibbils Pteropods depend on aragonite, a carbon derivative, to grow their shells. As the levels of dissolved inorganic carbon (DIC) in the ocean rise, seawater is becoming undersaturated with respect to aragonite. This has been shown to result in the degradation of pteropod shells, particularly in polar regions. As important pieces of global food chains, pteropods are important indicators of overall ecosystem “health.” Our study focused on the waters around New Zealand, sampling for pteropods and rating their degradation according to discoloration, corrosion, and physical damage. The most common species was Limacina Helicina, with occasional Limacina Retroversa and Clio Pyramidata present as well. Presence of Clione limacina antarctica and Spongiobranchaea australis were predicted, but were not observed. DIC levels were calculated via surface samples and did not exhibit any clear pattern with regards to location. When comparing the DIC at each sampling location to the damage seen in the pteropods, we saw a positive trend. Our research supports the growing scientific idea that ocean acidification, and thus the increase in DIC, is proving detrimental to aragonite-shelled organisms. Quantifying ocean currents around New Zealand – Allisa Dalpe and Ali Johnson New Zealand is home to multiple major ocean currents, but minimal research has been conducted on circulation in this region. By comparing data from the S256 cruise track (Auckland to Wellington to Dunedin and Lyttelton) and placing it within the context of general literature, our goal was to characterize these currents by direction and magnitude with additional help from temperature, depth, and salinity data.
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The currents characterized were the East Auckland Current, West Auckland Current, Westland Current, D’Urville Current, and the Southland Current. To look at a current direction and magnitude along our cruise track, we used an Acoustic Doppler Current Profiler (ADCP). In addition, we used a Current, Temperature, and Depth (CTD) Hydrocast to look specifically at the structure of the water column for the north tip of the North Island, Cook Strait, and the east side of the South Island. Along the north tip of the North Island, it was found that the current splits into the East and West Auckland Currents. As we expected, the currents through Cook Strait were very variable due to multiple converging currents, but generally flowed west to east. On the east side of the South Island, it was found that currents flowed north. Overall, the current direction data from the cruise track closely aligned with maps from published literature. Carbon dioxide fluxes in New Zealand waters – Sam Gartzman Increasing carbon dioxide (CO2) in the atmosphere is leading to changes in ocean chemistry across the world. As more CO2 is released, the ocean will absorb much of this carbon, changing ocean chemistry and thereby affecting marine organisms’ ability to create shells for protection. This study examined CO2 exchange, or fluxes, in the ocean around the coast of New Zealand. pH and total alkalinity measurements were taken from 31 surface samples to help determine the partial pressure of CO2 at the surface and eventually the flux of CO2. Analysis found unexpected positive fluxes (fluxes out of the ocean) at 30 of the 31 sampling sites. This suggests upwelling occurring at all of these sites. There was a trend of lower pH at colder waters, mainly due to the ocean’s ability to absorb more carbon at lower temperatures. Average wind speed data was taken to examine any relationships between wind speed and flux; however, the collected data does not show any correlation with flux. Coastal New Zealand waters do not have a lot of sampled data and this study is the start of examining the ocean chemistry and its effects on marine life. Exploring the potential for wave energy and combined wave-wind energy devices off the coast of New Zealand – Kristin McDonald No abstract prepared The spatial distribution of micro- and macroplastics in New Zealand waters – Anna Bute, Marine Lebrec and Kate Perkins Plastic pollution in the ocean is a global issue that continues to grow as manufacturing and consumption of plastic products increases. Macro- and microplastics are often not visible except through microscopes, which makes scientific quantification difficult. The full range of their effects on the marine environment is not completely understood, particularly in New Zealand waters where there is a lack of research on the subject. Through the course of the S256 cruise track, 44 surface water samples were taken to measure microplastic concentrations and 34 neuston nets were deployed to collect macroplastics. Overall, the plastic concentrations in New Zealand were variable in density and particle type. However, when compared to major gyre systems such as the North Atlantic and North Pacific, macroplastic and microplastic concentrations in these waters were considerably lower. Macroplastics were limited in quantity, 29 found in total along the cruise track, primarily consisting of polyethylene and polypropylene. These plastic types come from single-use packaged goods and fishing gear. Microplastic densities were found to follow known circulation patterns observed in past studies of New Zealand’s major currents. 2,923 microplastics were observed, the majority of which were filament pieces, indicative of fishing gear. This may be attributed to high fishing efforts surrounding the New Zealand Exclusive Economic Zone (EEZ). Assessing sediment transport from rivers to the ocean through relative calcium carbonate levels, transport systems and phytoplankton diversity in seafloor sediments – Briana Grenier, Kate Hruby and Karissa Vincent New Zealand, a series of islands with a volcanic landscape, contributes to the sediment load of the surrounding oceans. Much of this sediment comes from river runoff and erosion, influenced by human
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changes to the river systems before joining the sea and getting moved by currents, waves and wind. At three sites, sediment size was compared to distance offshore, the carbonate-to-terrigenous ratio was determined, and freshwater and marine diatoms were documented along offshore transects. Rangaunu Bay, Wellington Harbor and the Waitaki River were sampled. Rangaunu Bay held mostly larger (2000 and 500 µm grain sizes) and had calcium carbonate levels that exhibited a pattern with distance from river mouth, but not with pH. Wellington Harbor was comprised almost entirely of mud and clay (smaller than 63 µm grain sizes) and had calcium carbonate levels that related to pH as well as distance to the river mouth. The Waitaki River region of the Otago Shelf had mostly 2000 µm grain sizes until 7 nm offshore where the ratios evened out. Calcium carbonate at this location showed a trend with distance to the river mouth but not with pH. Sediment size and calcium carbonate patterns differed due to the vast array of landscapes, human alteration, erosion susceptibility, distances between grabs and exposure at each site.