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Blog Post: Water weeds. Love ‘em and leave ‘em be.

Water weeds. Love ‘em and leave ‘em be.

Alisha M. Saley

Growing up I was no different than the rest when it came to water “weeds”. I was terrified to feel the slime and whip-like stalks wrap around my legs as I waded into streams and lakes. The horrifying mixture of slippery rocks (diatoms), feather-like strands of filamentous algae on my legs, and squishing sediments between my toes sent strains of panic up my spine. As kids we perpetually persevere; my focus at the time to remain as close to the water surface as possible so as not to contact the dark abyss of the stream bottom (and the horrific photosynthesizers) again.

As it turns out, my disdain for the proliferation of these photosynthesizers was severely misplaced. In fact, most play a crucial role in supporting whole stream ecosystems. Other than providing a food source and refuge for small-bodied animals, they have sizable control over the hydrological flow of the system, specifically in smaller streams. Moreover, through uptake of excess nutrients (fertilizers from agriculture) into their tissue and the deceleration of flow (increasing sediment deposition) they serve as a biological filter. This ensures that the water that confluences with larger waterbodies downstream is less turbid (clearer), more oxygenated, and lower in superfluous nutrient concentrations.

With all biological beings, there is a threshold for functional success. Unfortunately, the increasing pressure we are putting on these systems to “clean up our extras” has surpassed their ability to remove our footprint. For example, we now have an annual, spring harmful algal bloom and hypoxic (low oxygen) zone that forms at the mouth of the delta of the Mississippi River (Figure 1). This bloom results from the transport and accumulation of excess nutrients (nitrogen and phosphorus) that were previously applied to farm fields upstream. This region of eutrophication (high productivity) stimulates toxin-producing algae to rapidly take up these nutrient resources, releasing toxins that are harmful to other animals (including humans). As nutrients deplete, the algae die and sink deeper in the water column. Microbes break down the dead tissue and through microbial respiration deplete the area of oxygen, making it unsafe for other species that require oxygen from the water to breathe. Those that are mobile flee the scene to areas of higher oxygen concentrations; however, many slow or sessile (non-moving) organisms are left to die.

figure 2

Although we have a general understanding of the aquatic cycling of nutrients, less understood is the relative roles that specific photosynthesizers have in uptake. For example, we know that for any one set of environmental conditions (light, temperature, flow, etc.), some photosynthesizers will be better competitors (i.e. will uptake more nutrients). However, natural conditions are ever-changing and as such, scientists now seek to understand what happens to shift in competition within communities (Figure 2). Therefore, along with mapping physical flows of nutrients, scientists are trying to map localized nutrient cycling in and out of organic material (photosynthesizers). This information can potentially aid management entities in creating natural, biological “nutrient barriers” (plant buffering zones) that sequester nutrients in pulse regimes, therefore reducing the impact agricultural entities have on neighboring waterbodies.

As an aquatic scientist I again find myself wading into the muck and grit and slime of streams, however my fear no longer stems from wispy plants and fuzzy algae. Instead I fear for ecosystems downstream of “the weeds”, as we already see how life is destroyed without their filtering capacity.

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Blog Post: The Hunt for Bryozoans

Getting ready to snorkel in the cold (!) Bodega Bay Harbor.
Getting ready to snorkel in the cold (!) Bodega Bay Harbor.

Isabelle Neylan

“Oh sweet Jesus!” The words are out of my mouth before I can stop myself, as fast as the cold water making it through the zipper of my wetsuit. I never seem to remember how cold the water is here in Bodega Bay until I’m in it. “Ah! Alright, let’s go!”

We wade the rest of the way into the water and put on our fins and prepare our snorkels. Yes marine scientists do get to snorkel for work sometimes, but no we are not in bikinis wading into tropical turquoise waters on our way to swim with dolphins. We’re here on this cloudy day in a boat marina scoping out the invertebrates that live on the docks and pilings in the harbor. 

I’m on the hunt for bryozoans. Unless you’ve taken an invertebrate zoology class, you may never have heard of them. The species I am hoping to study, Bugula neritina is probably one of the most innocuous, uncharismatic animals you will ever encounter. They resemble a very lackluster clump of algae or a sad tumbleweed. 

Believe me, I wasn’t sold the first time I heard about them either. But it turns out they are perfect for the kinds of questions I want to study. I’m interested in how the experiences of previous generations affect the current one.  For example, if your mother was stressed by something in her life, can that affect how you yourself handle that same stress in your own life? More and more evidence seems to say that the answer is yes. This type of parental effect is often called transgenerational plasticity. “Trans-” because the effects are across multiple generations and “plasticity” meaning an organism’s ability to change. It allows organisms to adapt more quickly to their environment because they are not just relying on their genes or their own current experiences. This ability may be important in our rapidly changing world and has been shown in a wide range of taxa from plants to humans. 

These bryozoans are weedy and grow quickly, have lots of babies, and are all over the docks and easy to collect. They’re also stuck in place so being able to adapt to a changing environment may be especially important. If temperatures rise, the pH sinks, or heavy metals are introduced into the harbor they can’t just swim away and find a better home. Can this type of plasticity help them cope with human created stressors? I’m very curious to find out. 

Marine science is filled with these kind of unsung heroes, the organisms that allow us to ask interesting and important questions. You’re probably not going to see the effects of climate change on multiple generations of whales for example, but you might be able to with an unassuming but still pretty amazing marine invertebrate. Back at the docks we slowly climb out of the water. The trip has been a success; I found my bryozoans! It means I can start my experiments and begin to tell their story.

An adult Bugula neritina collected from the docks.
An adult Bugula neritina collected from the docks.

 

An adult Bugula neritina seen under a microscope (x10 magnification). Each little animal is a clone that makes up one colony. The tiny tentacles are called lophophores and are used to feed on particles in the water.
An adult Bugula neritina seen under a microscope (x10 magnification). Each little animal is a clone that makes up one colony. The tiny tentacles are called lophophores and are used to feed on particles in the water.

 

A baby Bugula neritina
A baby Bugula neritina! (x40 magnification) The larvae swim for as little as a few minutes to a few hours in the water before finding a place to settle and begin to grow into adult colonies. With the naked eye, they look like little poppy seeds and are about the size of the period at the end of this sentence. 

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