Northwest Fisheries Science Center

Newportal Blog

A gateway to oceanographic adventures from the Newport Line and beyond

Blog on ocean conditions along the Newport Line and the northern CA Current.

Nearshore Phytoplankton

By Xiuning Du
Posted on April 17, 2017


Left side: diatom species Chaetoceros decipiens, cell 9-84μm wide, cosmopolitan species, relatively more abundant in the sample we examined. Right side: Skeletonema costatum, cell 2-21 μm in diameter, cosmopolitan species common in coastal regions, often forming blooms in spring.

Under the Yaquina Bridge at Newport, the Public Fishing Pier sits in close proximity to the entrance of Yaquina Bay and extends well into the primary tidal channel. Because the water that flows beneath the pier during flooding tides is strongly influenced by the open coast, coastal ocean phytoplankton species are commonly seen in the lower Yaquina estuary especially during the upwelling season (April to October).

Even though it feels like spring on land, we are still encountering storms from the south, signaling that the physical spring transition has not yet occurred in the ocean.

Diatom Chetoceros socialis, the other relatively more abundant species in the sample, forming large colonies, individual cell only 4-15 μm wide, commonly seen in the coastal waters.

 

 

But what are the marine phytoplankton doing?

We recently took a plankton sample to collect phytoplankton and zooplankton for the annual Hatfield Marine Science Day (on April 8th). In this tow, we observed a diverse set of diatoms forming long chains or colonies. These are diatom species that are commonly seen in the coastal waters off Newport and the abundance of these diatoms was relatively low (not blooming yet).  

We encountered gale force winds on the day when we collected this sample, and coastal surface currents from High Frequency radar showed very strong northward flow (50 cm/s). With the strong winds and the incoming tide, it is not surprising that offshore marine species (including potentially toxic algae such as Pseudo-nitzschia) were delivered into the Yaquina Bay on this day.

Diatom Stephanopyxis nipponica, cells 24-36 μm in diameter, northern temperate species, commonly seen off Newport.

Here we present photos of some of the relatively abundant species that we identified from the net tow sample at the Pier. Note that the records here are only a qualitative reference. By comparing the sample we collected in Yaquina Bay to samples we’ll collect when we sample the ocean in the coming weeks, we shall see: first, how coherent the distribution of phytoplankton community composition is between the very lower estuary of the Bay (the Pier) and the coastal waters offshore, and second how the phytoplankton assemblage changes once the upwelling season begins.

Pseudo-nitzschia australis cells present! Averaging 100 μm in length and in relatively low abundance. We do not know if these cells are toxic. This potentially toxic species has been seen in waters off Newport since mid-March (but were highly toxic in spring/summer 2015 and in autumn 2016). We’ll be watching how the numbers change in the following days from our next sampling cruises.
Diatom Odontella longicruris, cells 15-110 μm wide, warm to temperate species.
Diatom Rhizosolenia setigera, cells 4-20 μm in diameter, cosmopolitan species, commonly seen off Newport.

Tagged: NH Line

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