What is your favorite type of plastic to eat?

Oh are you going to tell me you don’t eat plastic? Unfortunately, there’s a real good chance that isn’t true. Let me tell you about this study by The University of Queensland, you might want to sit down for this. 

They looked at tissue samples of a variety of different species- 10 oysters, 10 farmed tiger prawns, 10 wild squid, five wild blue crab and 10 wild sardines. They found plastic in 100% of the samples they looked at. 

Of all the species they looked at they found Sardines had the highest amount of plastic. 

The study’s lead author said this “Considering an average serving, a seafood eater could be exposed to approximately 0.7mg of plastic when ingesting an average serving of oysters or squid, and up to 30mg of plastic when eating sardines, respectively …. For comparison, 30mg is the average weight of a grain of rice."

Now before you say “I don’t eat seafood, so I don’t have to worry.” If micro plastics have gotten into the tissues of sessile organisms that live on the bottom of the ocean, don’t for a second think they haven’t infiltrated our land based foods systems as well. 

To Read the full paper: https://pubs.acs.org/doi/pdf/10.1021/acs.est.0c02337

DDT Banned in 1972, But Still Poisoning Us and Our Oceans

Have you ever heard of DDT?

It was banned in 1972, but in order to get rid of the excess that was produced, nearly HALF A MILLION barrels of it were dumped in the the ocean off the coast of California in the San Pedro Basin, between Catalina and the Palos Verdes Peninsula.

Researchers have estimated there is 1,535 TONs of DDT on the sea floor, slowly oozing out of the dumped barrels.

Their existence has been known about for DECADES, and each time it was brought up (until recently) agencies brushed it aside, or just covered it with sand (literally) hoping it would go away on it's own.

But the “fun” thing about DDT is that it is very stable and doesn't break down. Instead it has been leeching out into the water, where it is collecting and bio accumulating in fish, dolphins, and other aquatic species as its makes its way up the food chain.

In October 2020, the dumped barrels made news headlines and in a few short months, scientists from Scripps were able to put together a team of 31 researchers, get a vessel (Sally Ride), and create a method to survey the area using the equivalent of deep sea rumbas.

The team started their work on March 10th 2021 and are expected to be finished on March 24th 2021.

Each of the ROV's deployed will survey the ocean floor for 12-16 hours before returning to recharge. While one is charging, one will be able to survey.

They hope to have the data available to be studied further approximately 30 days after the expedition on NOAA's website.

When Home Doesn't Sound Like it Used To

Waves crashing on the beach

What does your home sound like? Is it quiet? Loud? Are there kids playing or dogs barking? Do you hear trains or traffic in the background?

    If you think about it, our homes have a certain sound. Are you having a hard time figuring out what that sound is? Think about the last time you went away and had a hard time falling asleep because you missed the sounds of home.

    Just like our homes and habitats have a certain sound, so to do ocean ecosystems. (Check out my video of Aquarium of the Pacific, Pacific Visions sounds on the reef exhibit to hear what a reef sounds like) Now though, with increasing amounts of anthropogenic influences, aquatic habitats don’t sound the same and animals like Clownfish and whales, who use sound to navigate are having issues. 

While noise pollution might not seem like that big of a deal, it has had increasingly larger impacts on marine life. As anthropogenic noises (air guns, seismic testing, oil drilling platforms, cargo ships, speed boats, pile drivers, etc.) increase, the animals living in the oceans are facing more and more problems.

Consider the last time you were somewhere and you encountered a loud or unpleasant noise. What did you do? Most likely you left the area, which is what some of the larger species like whales and dolphins will do. Animals will often change their course to avoid loud areas like shipping lanes. But what about those smaller sessile species who can’t get away? They have been found to slowly migrate, leaving their native areas all together. Another example of issues it causes is one experienced by Clownfish. In their larval state they live in open water and as they grow they use sounds to help them navigate back to the reefs they will live on. With all the noise pollution, they are unable to tell which direction they need to swim to get to their reef.

  A recently released literature review looked at different studies done around the world with respect to aquatic species and noise pollution. The study’s authors looked at more than 10,000 papers about marine bio-acoustics from the past 20 years with the goal of compiling information that can be used to create policies that will bring about change. 

Researchers point out that noise pollution can cause physical damage to the animals. Some fish can regenerate cells used for auditory purposes, but mammals likely don’t have that ability. 

So, what can be done? While international cargo shipping, and oil drilling is not going to stop, there are changes that can be made to mitigate our impacts on the watery world and its inhabitants.

1. By moving shipping lanes, we can locate them in areas that have as small of an impact as possible. 

2. Reducing the speed of traveling vessels will help to reduce noise pollution they cause. 

3. Changing the types of propellers used to ones that produce fewer cavitation bubbles will quiet them.

4. Creating areas with sound barriers for oil platforms and deep sea drilling can reduce the impacted areas. 

    One of the unique, yet unplanned facets of this review is that the authors got to see the results of reduced noise pollution due to the pandemic slowdowns in commercial shipping. Dr. Carlos Duarte, the paper’s lead author said “Recovery can be almost immediate” as marine mammals and sharks began to return to areas when the shipping traffic slowed during 2020.  

    In the example at the beginning, when considering out home ecosystems, it should be noted that they are not quite, and nor are the oceans. Fish, marine mammals, and other organisms use sound to communicate with croaks, pops, snaps,  and songs. Waves crash, rocks tumble, and water splashes. The goal of this research is not to show us that we need to eliminate the noise we add to the oceans, but to work to make sure that our actions do not take away from the natural sounds of ocean habitats. 

To read the full article search for:  

“The Soundscape of the Anthropocene Ocean”. Carlos Duarte et al. 

Science 05 February 2021 ,Vol 371 Issue 6529

Can Stingrays Hear Sound?

Southern Stingray Photo by Hilary Jaffe

In 2019, Mickle et. al studied 20 different Southern stingrays (Hypanus americanus) in the waters surrounding the Bimini Biological Field Station. They placed underwater speakers in the pen with the stingrays and using a Sony Walkman, they played 5 different low frequency tones.

The 9 males and 11 females were tested individually and were exposed to 5 sound frequencies- 50Hz, 90Hz, 200Hz, 500Hz, and 1000HZ. Using a hydrophone they measured the sound level (in decibels) at 27 different locations inside the stingray’s enclosures.

Since a sound threshold for the rays was previously unknown, they started with 140dB , then depending on the stingray’s swimming behavior** , the sound was increased or decreased by 10dB or 5dB respectively making the levels tested- 130dB, 135 dB, 140dB, 150dB, and 160 dB.

What they found was both male and female stingrays exhibited behavioral differences. The average tone males responded to was 160dB while females responded more to 140dB.

With regard to frequency, males swimming activity increased at 50Hz, 90Hz, 200Hz, and 500 Hz and the females increased their activity at 50Hz, 90Hz, 200Hz, and 1000Hz.

The study looked at the following stingray behaviors- surface breaches, time spent resting, and side-swimming. Both males and females had significant increases in breaching events at 50 Hz, 90 Hz, and 200Hz. Resting rates for males and females decreased at 50Hz, 90Hz, and 200Hz and 50Hz, 90 Hz, 200Hz, and 500Hz respectively. At frequencies of 50Hz, 90 Hz, 200Hz, and 500Hz, both males and females showed increased rates of side-swimming.

If you would like to read their full article, you can find it here.

Mickle, Megan F et al. “Field assessment of behavioural responses of southern stingrays (Hypanus americanus) to acoustic stimuli.” Royal Society open science vol. 7,1 191544. 22 Jan. 2020, doi:10.1098/rsos.191544

** Animal trainers use similar observation to determine their animals level of enrichment and engagement.

How do Seahorses Feel About Paparazzi?

What do you do when you see something cool? ⁣ In the diving industry it's not uncommon for divers to use flash photography to capture the unique marine fishes swimming around them.⁣

⁣Up until recently the impacts of fash photography were unknown.  A study just released by Maarten De Brauwer and his colleagues, found that seahorses, in particular, were more impacted by the manipulation surrounding the photo then the flash itself.⁣

⁣Despite the 4,600 exposures to full power flash guns over 34 days there were no observable impacts on sea horse feeding behavior or foraging success.⁣

⁣While the flashes don't impact them we should still be respectful of these animals' environments and avoid harassment.⁣

⁣If you would like to read the whole article it is available to the public here:

https://www.nature.com/articles/s41598-018-37356-2

De Brauwer, Maarten, et al. "Behavioural and pathomorphological impacts of flash photography on benthic fishes." Scientific Reports 9.1 (2019): 748.