Spatial & Temporal Patterns of Microplastic Pollution in Wellington, New Zealand, and the Southern Ocean

<p>The global marine environment is currently facing unprecedented anthropomorphic change and stress. One such stressor is plastic pollution, which has continually increased in magnitude since mass production began in the 1940’s. An increase in plastic debris throughout the oceans not only results in an infiltration of the pollutants throughout the entirety of the marine environment, but also increases the risk that it impacts the physiological, structural, and behavioural traits of various organisms – including humans. These negative interactions are particularly likely with microplastic particles (< 5 mm), as they can enter and be transferred throughout the food web with ease. However, research in the field of microplastic pollution is extremely one-sided, with most present studies focusing on the Northern Hemisphere. Additionally, comparatively little has been investigated regarding temporal and spatial patterns of microplastic occurrence. The aim of this research was to 1) examine the abundance and distribution of synthetic particles in sub-surface waters of the Southern Ocean, across broad temporal and spatial scales and 2) examine finer-scale spatial and temporal patterns of microplastic load within the urbanised Wellington Harbour, New Zealand, using a combination of environmental and biological indicators. To assess the broad-scales of temporal and spatial variation in the Southern Ocean, annual Continuous Plankton Recorder (CPR) tows were undertaken between New Zealand waters and the Ross Sea, Antarctica, over a span of 9 years (the austral summers of 2009/10 – 2017/18) and a range of 5 oceanographic zones and two frontal systems, totalling a distance of approximately 22,000 km. Overall, patterns were inconsistent, with no constant increase or decrease in load throughout the years, while spatial variation was minimal and not associated with particular oceanographic fronts or proximity to an urban area. Despite no consistent spatial variation, temporal differences did occur between years. Again, there were no identifiably consistent trends across years (i.e. a gradual increase), but there was a substantial peak in 2009/10 and a trough in 2012/13. Such changes are likely due to large-scale variations in ocean circulation systems, along with environmental drivers such as El Niño and La Niña events. To investigate the microplastic load in a more urbanised environment, 3-monthly surveys were undertaken with surface waters, beach sediments, and M. gallloprovincialis mussels in Wellington Harbour, New Zealand, using samples from three sites for beach and mussel surveys, and two sites for the surface water tows. Weekly variation was also measured for beach sediments and mussel tissues. Again, no consistency was observed in temporal or spatial variation for any environmental or biological indicator, however the average pollutant loads were on par with reported results in other literature, particularly for M. galloprovincialis tissues. Temporally, the peak microplastic load in the tissues of the mussel, M. galloprovincialis, appeared to correlate with the peak load found within the surface waters of the harbour, indicating a possible relationship between plastic pollution in the environment and that which is found within organisms. Finally, the spatial variation observed within beach sediments was far larger than that seen throughout the mussel tissues, supporting the idea that beach sediments are microplastic sinks, but also susceptible to a range of environmental drivers including wind strength, wind direction, and sediment erosion. Throughout the Southern Ocean and within Wellington Harbour, particle characteristics were similar, in that microfibres were the prevailing synthetic morphotype – accounting for upwards of 90% of all particles found. These results are similar to reports from other current literature, but not associated with public knowledge that is currently in the media and represented in the legislation. The results of this thesis illustrate the importance of monitoring and managing the occurrence and effect of microplastics on both fine- and broad-scales of temporal and spatial variation and helps address the knowledge gap surrounding microplastics in the Southern Hemisphere.</p>

Spatial & Temporal Patterns of Microplastic Pollution in Wellington, New Zealand, and the Southern Ocean

<p>The global marine environment is currently facing unprecedented anthropomorphic change and stress. One such stressor is plastic pollution, which has continually increased in magnitude since mass production began in the 1940’s. An increase in plastic debris throughout the oceans not only results in an infiltration of the pollutants throughout the entirety of the marine environment, but also increases the risk that it impacts the physiological, structural, and behavioural traits of various organisms – including humans. These negative interactions are particularly likely with microplastic particles (< 5 mm), as they can enter and be transferred throughout the food web with ease. However, research in the field of microplastic pollution is extremely one-sided, with most present studies focusing on the Northern Hemisphere. Additionally, comparatively little has been investigated regarding temporal and spatial patterns of microplastic occurrence. The aim of this research was to 1) examine the abundance and distribution of synthetic particles in sub-surface waters of the Southern Ocean, across broad temporal and spatial scales and 2) examine finer-scale spatial and temporal patterns of microplastic load within the urbanised Wellington Harbour, New Zealand, using a combination of environmental and biological indicators. To assess the broad-scales of temporal and spatial variation in the Southern Ocean, annual Continuous Plankton Recorder (CPR) tows were undertaken between New Zealand waters and the Ross Sea, Antarctica, over a span of 9 years (the austral summers of 2009/10 – 2017/18) and a range of 5 oceanographic zones and two frontal systems, totalling a distance of approximately 22,000 km. Overall, patterns were inconsistent, with no constant increase or decrease in load throughout the years, while spatial variation was minimal and not associated with particular oceanographic fronts or proximity to an urban area. Despite no consistent spatial variation, temporal differences did occur between years. Again, there were no identifiably consistent trends across years (i.e. a gradual increase), but there was a substantial peak in 2009/10 and a trough in 2012/13. Such changes are likely due to large-scale variations in ocean circulation systems, along with environmental drivers such as El Niño and La Niña events. To investigate the microplastic load in a more urbanised environment, 3-monthly surveys were undertaken with surface waters, beach sediments, and M. gallloprovincialis mussels in Wellington Harbour, New Zealand, using samples from three sites for beach and mussel surveys, and two sites for the surface water tows. Weekly variation was also measured for beach sediments and mussel tissues. Again, no consistency was observed in temporal or spatial variation for any environmental or biological indicator, however the average pollutant loads were on par with reported results in other literature, particularly for M. galloprovincialis tissues. Temporally, the peak microplastic load in the tissues of the mussel, M. galloprovincialis, appeared to correlate with the peak load found within the surface waters of the harbour, indicating a possible relationship between plastic pollution in the environment and that which is found within organisms. Finally, the spatial variation observed within beach sediments was far larger than that seen throughout the mussel tissues, supporting the idea that beach sediments are microplastic sinks, but also susceptible to a range of environmental drivers including wind strength, wind direction, and sediment erosion. Throughout the Southern Ocean and within Wellington Harbour, particle characteristics were similar, in that microfibres were the prevailing synthetic morphotype – accounting for upwards of 90% of all particles found. These results are similar to reports from other current literature, but not associated with public knowledge that is currently in the media and represented in the legislation. The results of this thesis illustrate the importance of monitoring and managing the occurrence and effect of microplastics on both fine- and broad-scales of temporal and spatial variation and helps address the knowledge gap surrounding microplastics in the Southern Hemisphere.</p>

Temporal and spatial variation characteristics of temperature and its impact on grain production in Northeast China in recent 50 years

Climate warming has a great impact on grain production in northeast China, but there are few studies on the temporal and spatial variation characteristics of annual Tmean (mean temperature), the impact of meteorological factors on Tmean, and the impact of Tmean increase on grain production in northeast China. This study found that annual Tmean decreased from southeast to northwest in Northeast China, and there were regional differences in spatial distribution. The annual Tmean isoline in Northeast China moves obviously from southeast to northwest. The annual warming trend of Tmean was significant from 1971 to 2000, and moderated from 2001 to 2020. In recent 50 years, Tmean had obvious periodic changes. In the mid-late 1980s, annual Tmean had a sudden warming change, and since then it has been rising continuously. Sunshine hours, average wind speed, evaporation and average air pressure had a very significant correlation with Tmean. In conclusion, the climate change in northeast China in the past 50 years has an obvious warming and drying trend, and there are regional differences in the warming and drying. The warming and drying climate has brought challenges to agricultural production and food security in Northeast China. However, the negative effects of grain production reduction caused by warming and drying climate can be avoided to a certain extent if we deal with it properly.

Temporal and spatial variation in sex-specific abundance of the avian vampire fly (Philornis downsi)

Understanding the range and behaviour of an invasive species is critical to identify key habitat areas to focus control efforts. Patterns of range use in parasites can differ temporally, across life stages and between sexes. The invasive avian vampire fly, Philornis downsi, spends the larval stage of its life within bird nests, feeding on developing nestlings and causing high levels of mortality and deformation. However, little is known of the ecology and behaviour of the non-parasitic adult fly life stage. Here, we document sex-specific temporal and spatial patterns of abundance of adult avian vampire flies during a single Darwin’s finch breeding season. We analyse fly trapping data collected across 7 weeks in the highlands (N = 405 flies) and lowlands (N = 12 flies) of Floreana Island (Galápagos). Lowland catches occurred later in the season, which supports the hypothesis that flies may migrate from the food-rich highlands to the food-poor lowlands once host breeding has commenced. Fly abundance was not correlated with host nesting density (oviposition site) but was correlated with distance to the agricultural zone (feeding site). We consistently caught more males closer to the agricultural zone and more females further away from the agricultural zone. These sex differences suggest that males may be defending or lekking at feeding sites in the agricultural zone for mating. This temporal and sex-specific habitat use of the avian vampire fly is relevant for developing targeted control methods and provides insight into the behavioural ecology of this introduced parasite on the Galápagos Archipelago.

Fin Whale (Balaenoptera physalus) in the Ligurian Sea: Preliminary Study on Acoustics Demonstrates Their Regular Occurrence in Autumn

The patterns of movement of the fin whale (Balaenoptera physalus (Linnaeus, 1758)) in the Mediterranean Sea are still a matter of debate. Feeding aggregations are well known in the Corso-Liguro-Provençal Basin from July to September, but little is known for the autumn and winter seasons. Passive acoustic monitoring (PAM) was implemented in the Ligurian Sea to overcome this gap and to investigate the temporal and spatial variation of fin whale acoustic presence. From July to December 2011, five autonomous recorders were deployed at between 700 and 900 m depths. Fin whale calls were automatically detected almost every day, with higher vocalization rates in October, November, and December. Furthermore, daily vocalization rates were higher during light hours, and closer to the coast. These outcomes suggest that not all the individuals migrate, staying in the area also during autumn for feeding or breeding purposes. The dial cycle of vocalization might be related to feeding activities and zooplankton vertical migration, whereas the proximity to the coast can be explained by the morphology of the area that promotes the upwelling system. Although this work only represents a six-month period, certainly it suggests the need for a larger spatial and temporal PAM effort, crucial for species management and for mitigating possible impact of anthropogenic activities at the basin level.