you're reading...


From Wastewater to Seahorses to the Medicine Cabinet

Zhang, Wei, et al. “Bioaccumulation of Metals in Tissues of Seahorses Collected from Coastal China.” Bulletin of environmental contamination and toxicology 96.3 (2016): 281-288.


Pollution along coastal waterways can have negative impacts on the environment that may put human health at risk. For example, scientists fear that marine pollutants, like metals, will be a residual in a medicine derived from seahorse tissue, and they are concerned for the potential harm it may have on patients.

Metal pollution is most prevalent in areas that have a lot of people, and a lot of growth and expansion.   These types of communities create a lot of waste products through civilians, like sewage and automobile exhaust, and industry, like mining, electronic waste recycling, and smelting (the process of extracting metal from it’s ore source). Metals are transported from coastal areas to the marine system by wastewater, runoff, and wind. Wind is a big factor in the distribution of automobile exhaust, which contributes to the pollution of cadmium (Cd) and lead (Pb).

Once in the water column, the metals either are consumed or settle out. Eventually, they can work their way into and up the food chain, and accumulate in the tissues of consumers, like seahorses.

Figure 1: H. trimaculatus (source: https://commons.wikimedia.org/wiki/File:Hippocampus_trimaculatus,_Osezaki.jpg)

Figure 1: H. trimaculatus (source: https://commons.wikimedia.org/wiki/File:Hippocampus_trimaculatus,_Osezaki.jpg)

Seahorses (figure 1) are neat little sea creatures. Their use in medicine and unique appearance make them a popular catch. They live near the bottom of shallow (10’s meters) and warm bays and estuaries in mid to low latitudes.   They are often found in areas of seagrass, mangroves, and coral reefs. Seahorses are carnivorous, however, they have relatively small appetites and their digestive system is not very good at reaping the benefits of what they do consume. Nonetheless, they are still living in environments impacted by pollution so the possibility of metal contamination in their tissues that would translate into human medicine is a real threat.


An early step in studying the threats to human health from metals in seahorse tissues used to make medicine is to determine if the metal pollutants are accumulating in seahorses’ tissues.   Scientists sampled specimen from six locations along the coast of China so that their study would represent both developed and under developed regions. The sampling locations included Qingdao (figure 2), Zhoushan, Xiamen, Shanwei, Zhanjiang, and Beihai. Sampling was completed during October and November in 2010 with the aid of local fishing vessels.   A total of four different species of seahorses were caught: Hippocampus trimaculatus, Hippocampus histrix, Hippocampus kelloggi, and Hippocampus kuda.  H. trimaculatus were caught in every location except for Shanwei, where H. kuda was caught instead. At Xiamen and Zhanjiang, H. histrix and H. kelloggi were caught in addition to H. trimaculatus, respectively.

City of Qingdao (source: https://en.wikipedia.org/wiki/Qingdao#/media/File:City_View_Of_Qingdao)

City of Qingdao (source: https://en.wikipedia.org/wiki/Qingdao#/media/File:City_View_Of_Qingdao)

Specimens brought back to the laboratory were dissected. The tissues were then dried, powered, and digested for further analysis. Concentrations of metals (aluminum, barium, cadmium, cesium, chromium, copper, magnesium, manganese, and lead) were measured on an ICP-MS (inductively coupled plasma mass spectrometer). Figure 1 in the original article maps the locations for sampling, the types of seahorses sampled, and the metal concentrations of the seahorses sampled.


Overall the metal with the greatest concentrations in seahorse tissue was magnesium, followed by aluminum and manganese.   Figure 2 in the original article illustrates the results for each element in each species in bar graphs.

Scientists found that the metal concentrations varied by sample location, species, and tissue type.

The variation in metal accumulation with respect to location was investigated with H. trimaculatus because it had a large distribution range. Researchers speculate that the concentration differences between locations may reflect industrial activity and civilian land use resulting in the discharge of metal-containing wastewater into the coastal waters.   For instance, the high levels of metals measured in the tissues of seahorses from Qingdao and Xiamen are likely attributed to those areas both having experienced fast economic development. In comparison, areas like Zhoushan and Beihai are popular tourist destinations and as a result have much less industrial wastewater discharging into and polluting the coastal waterways.

Accumulation differences found between the different types of species were observed and may be related to appetite differences between species.   For example, H. kelloggi had greater amounts of metal accumulation than H. trimaculatus and scientists think the elevated metal concentrations observed in H. kelloggi may be explained by the diet a heavy in benthic prey. Benthic organisms are susceptible to metal contamination because of their location at the bottom of the water column where all the sediments and pollutants settle out.   Additional explanations for the variation in metal concentrations observed between species include differences in kinetic properties of the metals, and differences in physiological functionality between species.

Scientists also found that metal concentration varied with tissue type. Greater levels of metal were measured in muscle and skin tissues and lesser amounts were measured in the brain, gill, and skeletal tissues. The tissue variation was different between species and was very irregular; the results are summarized in table 2 of the original article.

Compared with marine fish in the same areas, the seahorses had lesser amounts of cadmium, chromium, manganese, and lead, but a greater concentration of copper.   The metals with lower concentrations can be explained by the low consumption rate by the seahorses; because the seahorses do not eat much, they are not susceptible to accumulating a lot of metal in their tissues. The copper, however, is less straightforward. Researchers find the high concentration of copper in seahorse tissue relative to marine fish quizzical because they did not find that the seahorses up took the copper quickly nor did they find the copper in forms readily available for uptake. Why copper is able to accumulate in the tissues of seahorses is a topic for further investigation.

Scientists on this paper took a first step to assessing the threat of metal pollutants on human health with respect to their residual imprint in medicines derived from seahorse tissues.   They found that seahorses do accumulate metal in their tissues, but not as much as fish do, and there is a lot of variability between location, species, and tissue type.   Their research is important for human health, but also to understand how pollution is impacting the health of the marine system.   Responsible waste management can be an advantage in conserving seahorse populations, which are low enough to have the seahorse listed on the endangered species list by the Convention on International Trade in Endangered Species of Wild Fauna and Flora.


2 Responses to “From Wastewater to Seahorses to the Medicine Cabinet”

  1. Article: From Wastewater to Seahorse to the Medicine Cabinet  Author: Anne M. Hartwell
    Pollution has many negative effects on the environment. Metal pollutants that drain into the oceans are eaten by seahorses. These metals end up in the seahorses’ tissues. Many medicines are made by these tissues and patients who consume these medicines put their health at risk. To see if the metal accumulated inside the seahorse tissues, scientists sampled six different specimens located near the coast of China and dissected them. The tissues were dried, powered, and digested sfor further analysis. They found that metal concentration depended on the location, seahorse species, and the tissue type. They also found that the seahorse tissue mostly contained  magnesium and alluminum. Metal concentrain also depends on what a species eats. For example, if one species’ diet consisted of plankton that contained metal in its tissues , then it would have a higher metal concentration than a species that ate plankton without metal in its tissues. It is important to manage our waste so that we do not affect other animals and so we do not risk peoples’ health.
    Question- Are there any other methods, besides managing our waste, to make sure metal does not affect marine animals? Is it possible to check medicine if it contains metals so we do not harm our health?

    Posted by Drishti | March 5, 2017, 9:31 pm
    • Hey Drishti!

      Welcome to Oceanbites.org and thank you for commenting.

      Managing waste that eventually is transported into the ocean is a huge umbrella. Metals can from waste, like trash, but it can also come from emission and it can be leached from materials that we bury for infrastructure, for examples. On a regional, national, and international scale it is important that agencies oversee activities to try an limit the metals that are released into the environment. Like we learned in the article, when metals accumulate in an animals tissue it can have long term health impact, so the less we add to the environment from various sources, the better. Metals do exist in the natural environment (think about the metals listed on the periodic table- like iron or lead!), so we’ll always expect that some will be detected.
      As for checking if your medicine contains metals, I imagine that you could reference the label on the bottle. You could also ask your pharmacist, or find an accredited internet resource. And just like in natural enviornment, there is some metal that is naturally occurring in our bodies. For example our blood has a level of iron, and if it’s too low you can’t donate blood! Usually a nice healthy serving of spinach can help get the lead levels back up though!

      Thanks for reading my post, i hope this helps answer your questions!


      Posted by Anne M. Hartwell | March 5, 2017, 10:23 pm

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 6 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 9 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 10 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 11 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com