Abstract:Qualitative and quantitative data for picophytoplankton from the Hauraki Gulf, northeast New Zealand, were gathered from May 1986 to February 1987. Records for both whole and sizefractionated samples (net-, nano-, and picophytoplankton) allowed the relative contribution by the picophytoplankton to total biomass and overall rates of carbon fixation to be estimated. Picophytoplankton represented a mean value of over 30% of the total chlorophyll a in winter and c. 20% in other seasons. In terms of total carbon fi… Show more
“…The volume of the reniform-shaped cells was larger than that of the coccoid cells. This feature was also noted in both oceanic and coastal waters (Booth and Sondergaard, 1989;Glover et al, 1986). Larger volume of reniform-shaped cells might be the results of greater pigment contents and the cells might change to this shape under low light conditions to strengthen its photosynthetic efficiency.…”
Section: Spatial Distribution Of Picophytoplankton and Nanophytoplankmentioning
In order to understand the large-scale spatial distribution characteristics of picoplankton, nanophytoplankton and virioplankton and their relationship with environmental variables in coastal and offshore waters, flow cytometry (FCM) was used to analyze microbial abundance of samples collected in summer from four depths at 36 stations in the North Yellow Sea (NYS). The data revealed spatial heterogeneity in microbial populations in the offshore and near-shore waters of the NYS during the summer. For the surface layer, picoeukaryotes were abundant in the near-shore waters, Synechococcus was abundant in the offshore areas, and bacterial and viral abundances were high in the near-shore waters around the Liaodong peninsula. In the near-shore waters, no significant vertical variation of picophytoplankton (0.2-2μm) abundance was found. However, the nanophytoplankton abundance was higher in the upper layers (from the surface to 10 m depth) than in the bottom layer. For the offshore waters, both pico-and nanophytoplankton (2-20μm) abundance decreased sharply with depth in the North Yellow Sea Cold Water Mass (NYSCWM). But, for the vertical distribution of virus and bacteria abundance, no significant variation was observed in both near-shore and offshore waters. Autotrophic microbes were more sensitive to environmental change than heterotrophic microbes and viruses. Viruses showed a positive correlation with bacterial abundance, suggesting that the bacteriophage might be prominent for virioplankton (about 0.45μm) in summer in the NYS and that viral abundance might play an important role in microbial loop functions.
“…The volume of the reniform-shaped cells was larger than that of the coccoid cells. This feature was also noted in both oceanic and coastal waters (Booth and Sondergaard, 1989;Glover et al, 1986). Larger volume of reniform-shaped cells might be the results of greater pigment contents and the cells might change to this shape under low light conditions to strengthen its photosynthetic efficiency.…”
Section: Spatial Distribution Of Picophytoplankton and Nanophytoplankmentioning
In order to understand the large-scale spatial distribution characteristics of picoplankton, nanophytoplankton and virioplankton and their relationship with environmental variables in coastal and offshore waters, flow cytometry (FCM) was used to analyze microbial abundance of samples collected in summer from four depths at 36 stations in the North Yellow Sea (NYS). The data revealed spatial heterogeneity in microbial populations in the offshore and near-shore waters of the NYS during the summer. For the surface layer, picoeukaryotes were abundant in the near-shore waters, Synechococcus was abundant in the offshore areas, and bacterial and viral abundances were high in the near-shore waters around the Liaodong peninsula. In the near-shore waters, no significant vertical variation of picophytoplankton (0.2-2μm) abundance was found. However, the nanophytoplankton abundance was higher in the upper layers (from the surface to 10 m depth) than in the bottom layer. For the offshore waters, both pico-and nanophytoplankton (2-20μm) abundance decreased sharply with depth in the North Yellow Sea Cold Water Mass (NYSCWM). But, for the vertical distribution of virus and bacteria abundance, no significant variation was observed in both near-shore and offshore waters. Autotrophic microbes were more sensitive to environmental change than heterotrophic microbes and viruses. Viruses showed a positive correlation with bacterial abundance, suggesting that the bacteriophage might be prominent for virioplankton (about 0.45μm) in summer in the NYS and that viral abundance might play an important role in microbial loop functions.
“…Continuous feeding is possible due to the year round availability of fish (Kendrick and Francis 2002) and zooplankton (Jillett 1971) within these productive waters. The East Auckland Current is the primary reason for this high productivity (Booth and Sondergaard 1989, Chang et al . 2003), and explains the extensive marine biodiversity within this region (Kendrick and Francis 2002).…”
Section: Discussionmentioning
confidence: 99%
“…Continuous feeding is possible due to the year round availability of fish (Kendrick and Francis 2002) and zooplankton (Jillett 1971) within these productive waters. The East Auckland Current is the primary reason for this high productivity (Booth andSondergaard 1989, Chang et al 2003), and explains the extensive marine biodiversity within this region (Kendrick and Francis 2002). Previously, authors E263 have suggested that Bryde's whale abundance is strongly related to upwelling systems which result in higher rates of primary productivity, as demonstrated off Chile (Gallardo et al 1983), eastern tropical Pacific (Ballance et al 2006) and for the inshore form off South Africa (Best 1960).…”
Section: Seasonal Occurrence and Geographic Distributionmentioning
The Hauraki Gulf is a large, shallow embayment located north of Auckland City (36°51′S, 174°46′E), New Zealand. Bryde's whales (Balaenoptera edeni) are the most frequently observed balaenopterid in these waters. To assess the use of the Hauraki Gulf for this species, we examined the occurrence and distribution in relation to environmental parameters. Data were collected from a platform of opportunity during 674 daily surveys between March 2003 and February 2006. A total of 760 observations of Bryde's whales were recorded throughout the study period during 371 surveys. The number of Bryde's whales sighted/day was highest in winter, coinciding with the coolest median sea‐surface temperature (14.6°C). Bryde's whales were recorded throughout the Hauraki Gulf in water depths ranging from 12.1–59.8 m (mean = 42.3, SD = 5.1). Cow–calf pairs were most frequently observed during the austral autumn in water depths of 29.9–53.9 m (mean = 40.8, SD = 5.2). Data from this study suggest Bryde's whales in the Hauraki Gulf exhibit a mix of both “inshore” and “offshore” characteristics from the Bryde's whales examined off the coast of South Africa.
“…Strong coastal upwellings make the study area an extremely productive (Booth & Søndergaard 1989) and biologically diverse region (Stockin et al 2008b). Seasonal upwelling occurs in the later austral winter to early spring, when prevailing westerly winds introduce nutrients into surface waters, which elevates spring chlorophyll-a levels in the outer Gulf and along the outer shelf (Chang et al 2003;Zeldis et al 2004).…”
We present the first fine-scale data relating to the occurrence and group characteristics for killer whales (Orcinus orca) in the Hauraki Gulf, New Zealand, as observed from a platform of opportunity (PoP). Group size and composition were examined in relation to water depth and sea surface temperature (SST). From 2000 to 2010, 119 orca encounters were recorded, involving 1 to 18 animals. The encounter rate varied seasonally, being highest in austral spring and lowest in summer. Water depth in which whales were observed was significantly affected by group composition. Sixty-seven percent of groups contained immature animals. Group size was highly skewed towards smaller groups comprising two animals. While this study illustrates that PoPs can be used to indicate the occurrence and group characteristics of highly mobile social species, biases clearly exist. Through identifying such inaccuracies, we present recommendations on how future data should be collected to minimise error and improve datasets for scientific use.
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