Tag Archives: background

What’s the goal of this research project?

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The underlying objective of this research project is centered on a small-scale front and its associated biological activity. A front is a meeting of two water masses, and oceanic fronts are generally broken up into several broad categories, depending on the physical environment and phenomenon that cause these water masses to converge. Oceanographers have been interested in fronts for a long time, because they tend to be areas of high productivity. The elevated productivity at fronts is a result of the converging water masses physically aggregating many marine organisms.

Small-scale fronts are, as the name suggests, smaller in spatial scale: they tend to occur on the order of tens of kilometers instead of hundreds to thousands of kilometers like some of the other major fronts. Small-scale fronts occur frequently, but have also been harder to describe because they are more ephemeral than large fronts.

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Sampling region in the Southern California Bight (SCB)

We set out to study one particular small-scale front in the Southern California Bight (SCB, see map for study region) because it was in an area that has received long-term oceanographic investigation – it is always good to do studies where there is lots of baseline data. We were primarily interested in exploring what biota was out there and seeing if there was biological aggregation at the front.  Indeed there was! We saw a large aggregation of our now favorite jellyfish, Solmaris rhodoloma, at the front and described it in a 2012 research paper. You don’t have to worry about reading it. It basically says what I just told you: we found a lot of Solmaris at this small-scale, salinity-driven front.

Solmaris rhodoloma aggregation

Solmaris rhodoloma aggregation

One of the interesting things about Solmaris is that they are part of a family of medusae that predate exclusively on other gelatinous zooplankton. They have been known to eat arrow worms and doliolids, but now, because of our images, we also think they are eating larvaceans and small siphonophores as well. So finding the large aggregation of Solmaris actually generated another research question for us: what’s going on with the rest of the gelatinous zooplankton at and around this front? What are the main processes driving their distribution? Is predation pressure from Solmaris affecting them in any way?

It turns out that the second question is much harder to answer than you would think. Not knowing exactly what Solmaris is eating, and how long they’ve been accumulating at the front makes it difficult for us to tell if they’re just happening upon a patch of prey or they have already eaten everything around them. One approach is to determine the movements and directions of the organisms, which is why we’re asking you to measure their orientation. We hope that knowing their orientation (and that of their potential prey) can help us model their movement patterns and “age” the Solmaris aggregation, so to speak. Of course, it’s possible that even with this data we will still not be able to determine how long Solmaris has been aggregating at the front. However, this kind of orientation information has never been acquired for jellyfish of this size and at this scale, so any data we gather will be new and interesting!

This is just one of many questions that Plankton Portal can help answer.  The biological data contained within these images can bring us closer to a greater understanding of zooplankton ecology in general.  Understanding the abundance, distribution and biomass (that’s where the size measurements come in) of this extremely understudied group of organisms – the small gelatinous zooplankton – can help us assess their broader impact in the marine food web, contribution to carbon cycling, and even help us learn how to identify hotspots of marine productivity in the future. This is how research grows and develops: it starts from a small, initial question (“hmm, I wonder if there is anything interesting at a small offshore front?”), which leads us to additional questions, and down the road, will hopefully help mankind appreciate and better protect its precious marine resources.

Thank you for your help and participation in Plankton Portal – you are contributing to a more knowledgeable future and hopefully one where we can better care for the sea around us.

Welcome to the Plankton Portal!

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Plankton species are a beautiful and fascinating group of organisms. We can’t wait to show you what we have seen of these diverse and elusive critters.  Let us start from the beginning—the five W-questions:

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What is plankton?
The word Plankton comes from the Greek word planktos meaning “wanderer” or “drifter”.  They are a group of organisms that are too small or too fragile to swim against naturally occurring currents. Plankton inhabit both freshwater and marine environments, such as lakes, ponds, and oceans.  Plankton can be broadly divided into two main groups: phytoplankton (plants) and zooplankton (animals). Phytoplankton are one of the primary producers in the ocean; like plants, they carry out photosynthesis to covert inorganic nutrients and light energy into organic material. Zooplankton, on the other hand, graze on phytoplankton or consume other zooplankton smaller than themselves. While you might think that plankton are too small to be seen by unaided eyes; that is not entirely true. Planktonic organisms have a very wide range in sizes. Many of them are microscopic in size; but others, like jellyfish, could grow up to more than one meter long.

Why do we study plankton?
Plankton are crucial to the marine ecosystem.  As a group, plankton form the basis of many marine food webs in that they are an important food source to organisms ranging from larval fish to the largest animal on earth—the blue whale. In addition, plankton play an important role in nutrient cycling in the ocean; such as carbon and nitrogen cycle.  Even humans are affected by plankton. As plankton are a food source for many marine organisms, our fishery industries depend highly upon these planktonic organisms as a source of fish productivity. Beyond being food, some plankton can also create problems to the fishing industry and even tourists visiting the shore when forming noxious blooms such as red tides.

How do we study plankton?
There are several ways to sample plankton: bottles, nets, acoustics, imaging systems, etc. Nets are the most common way of plankton sampling. Nets of different size, shape and design are used depending on the type of plankton of interest. A net is towed behind a moving vessel at the desired depth in order to collect and concentrate the planktonic organisms. When the net moves through the water column, plankton is retained in the net. One on board, the plankton ‘slurry’ is removed from the net and then (usually) preserved for later viewing and analysis under a microscope in the laboratory.

In this project, we sampled plankton by using a plankton imaging system – In Situ Ichthyoplankton Imaging System (ISIIS). ISIIS acts as a “virtual net” which captures the images of the organisms and information about their immediate surroundings. By sampling continuously, the result is a collection of digital images that record the exact location of the various planktonic organisms in relation to each other and the environment in which they live.

Where and when
The images currently shown in the Plankton Portal were taken in the Southern California Bight approximately 30 miles south of San Nicolas Island on October 15-17, 2010, on board the NOAA Ship Bell M. Shimada. But we are continuously traveling the world to bring new images and better understand how these little guys make a living in the ocean! ISIIS has also been towed in the Atlantic off of Georges Bank and Stellwagen Bank, MA, Straits of Florida, Gulf of Mexico, and recently off southern France in the Mediterranean.

This current project is to study the aggregation (patchiness) and distribution of different plankton in a small-scale front (where two different water masses meet) in the SCB. We want to know which organisms are present at the front (vs. those that may avoid it), and what they are doing there (e.g. are they prey or predators?). We need your help in identifying the organisms captured by ISIIS.