Tag: fish

Vivid orange killifish discovered in the Brazilian Amazon

Researchers have described a new species of brilliantly coloured fish from a network of forest streams in the Brazilian Amazon, and have already recommended it for listing as Endangered because of the pressures facing its only known home.

The fish, named Laimosemion laranja, is a killifish measuring less than three centimeters in standard length. Males are strikingly patterned, with rows of orange spots along the front half of the body and bold, chevron-shaped orange bars towards the tail, set against a pale grey flank.

Laimosemion laranja new species, INPA–ICT 062601, Paratype, female, 20.1 mm SL: Brazil, Amapá, Laranjal do Jari, Rio Cajari, Amazonas Basin. Photo: Yuri Abrantes.
Laimosemion laranja new species, INPA–ICT 062600, Holotype, male, 26.8 mm SL: Brazil, Amapá, Laranjal do Jari, Rio Cajari, Amazonas Basin. Photo: Yuri Abrantes.

It was found by Brazilian researchers from the Universidade Federal do Rio Grande do Norte, the Instituto Peixe das Nuvens, the Universidade Federal do Pará and University of West Florida, during fieldwork in the Rio Cajari drainage in the southern state of Amapá.

“We are developing a research project aimed at investigating the evolution of life-history strategies in freshwater fishes of the family Rivulidae across different biomes in Brazil.

During our sampling in small rivers locally known as ‘igarapés’ in the Rio Cajari region, in Amapá State, we found this fish with a very striking coloration, which immediately caught our attention.”
Yuri Abrantes of the Universidade Federal do Rio Grande do Norte

The research team with Laimosemion laranja. Photo credit: Yuri Abrantes.
Waldir Miron Berbel-Filho with Laimosemion laranja. Photo credit: Yuri Abrantes.

Confirming that the fish was new to science required close comparison of its body proportions, scale counts and skeletal features against its closest relatives, together with an analysis of its mitochondrial DNA.

“It was an unexpected moment. Initially, what most caught our attention was the impressive coloration of the males and females, which was unlike anything we had previously encountered in the study area. This sparked our admiration and a great deal of curiosity.”
Yuri Abrantes

*Laimosemion laranja* sp. nov. Photo credit: Yuri Abrantes.

Once the genetic analysis confirmed the fish’s distinct identity, he said:

“It was something special, as we saw an opportunity to contribute to increasing our knowledge of Amazonian biodiversity and to draw attention to the conservation of areas that are still poorly explored but highly threatened.”

The species’ name, laranja, is Portuguese for both the colour orange and the fruit, a fitting nod to the males’ vivid markings. It also honours Laranjal do Jari, the Amapá municipality where the fish was found.

“We wanted to choose a name that would highlight a characteristic of the fish while also fostering a sense of connection with the people of the region where it was discovered.”
Yuri Abrantes

Habitat of Laimosemion laranja. Photo credit: Yuri Abrantes.

Laimosemion laranja belongs to a group of Amazonian killifish, some of which have evolved an unusual survival strategy: their embryos can pause development entirely, lying dormant in damp mud until seasonal pools refill with rain.

“Laimosemion represents one of the five independent origins of the annual life cycle within the family Rivulidae.

Laimosemion laranja is particularly interesting because it expands our knowledge of the diversity and evolution of this group in the region.”
Yuri Abrantes

The new species is currently known from just three small forest pools near Laranjal do Jari, all showing signs of disturbance from deforestation, mining and urban expansion; one site lies close to water discolored by mining sediment, while another, within the city itself, is affected by plastic pollution.

Laimosemion laranja in its habitat. Video credit: Yuri Abrantes.

With its entire known range covering an estimated 25 square kilometers, the researchers argue that Laimosemion laranja meets the criteria for an Endangered listing under IUCN guidelines, and have recommended extending the boundaries of the neighboring Rio Cajari Extractive Reserve to help protect it.

The study is published in the open-access journal Zoosystematics and Evolution.

Original source:

Abrantes YG, Lima SMQ, Nielsen DTB, de Lira FO, da Silva MJ, Berbel-Filho WM (2026) A new killifish of the genus Laimosemion (Cyprinodontiformes, Rivulidae) from Rio Cajari in the Brazilian Amazon. Zoosystematics and Evolution 102(4): 1079-1088. https://doi.org/10.3897/zse.102.187659

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Year of the Horse 2026: A selection of equine-related species to celebrate the Lunar New Year

Pensoft celebrates the Year of the Horse by showcasing scientific discoveries of equine-adjacent species.

Lunar New Year is a celebration of the arrival of spring and the beginning of a new year on the lunar calendar. As the most important holiday in China, it is also widely celebrated across Korea, Vietnam, and other countries with a substantial Chinese diaspora.

In celebration of 2026 as the Year of the Horse, we reviewed our journals for horse-related studies. While our recent publications do not focus on horses themselves, we have highlighted several fascinating species that share an equine connection in their names.

2026 may be the Year of the Fire Horse, but we start our series with a creature of the opposite element: the seahorse!

*Hippocampus* *japapigu* in situ, Hejie, Kenting, Taiwan. (Photo credit: Chao-Tsung Chen).

Monitoring tiny, cryptic pygmy seahorses can be costly and logistically challenging. To overcome this, researchers from Taiwan turned to citizen science, gathering photographs from divers and underwater photographers via social media. Five species were identified, including two never before recorded in the region.

Among them is the charismatic “Japan pig” seahorse, Hippocampus japapigu, originally described from Japan in the open-access journal ZooKeys.

At the time, only seven pygmy seahorses had been identified globally. Documenting five of them in Taiwan established the region among the world’s biodiversity hotspots for these miniature fish.

Read more: ZooKeys 883: 83–90. https://doi.org/10.3897/zookeys.883.39662

But seven did not remain the final count for long. In Chinese tradition, eight is considered an auspicious number, associated with prosperity and good fortune.

Enter Hippocampus nalu – the eighth recognized pygmy seahorse species!

*Hippocampus* *nalu* in situ, Sodwana Bay, South Africa at 14 m depth. (Photo credit: Richard Smith, oceanrealmimages.com).

It is also the first confirmed true pygmy seahorse recorded from Africa. Measuring just 20 mm, this tiny species was discovered at depths of 17 m on a sandy coral reef in Sodwana Bay, South Africa.

Read more: ZooKeys 934: 141–156. https://doi.org/10.3897/zookeys.934.50924

Seahorses also feature in a remarkable Mediterranean story…

A study published in Acta Ichthyologica et Piscatoria documented a stable and conspicuous population of the long-snouted seahorse, Hippocampus guttulatus, in a highly polluted coastal lagoon in the Ionian Sea.

*Hippocampus guttulatus* observed during the diving visual census carried out in the Mar
Piccolo of Taranto (Ionian Sea), 2011-2013. (Photo credit: Francesco Tiralongo and Rossella Baldacconi).

Through three years of diving surveys, amounting to 69 hours underwater, researchers recorded 196 sightings. The seahorses showed a clear preference for artificial hard substrates, while only a few individuals were found in algal meadows.

Despite environmental fluctuations and pollution, the population persists. In the Year of the Horse, we wish you the same resilience and strength!

Read more: Acta Ichthyologica et Piscatoria 44(2): 99–104. https://doi.org/10.3750/AIP2014.44.2.02

Fish is a traditional Lunar New Year dish, symbolising abundance and good fortune. While you won’t find a horsefish at the markets of Hainan, China, you can certainly spot a ponyfish.

Researchers have reported the first confirmed record of Aurigequula striata in Chinese waters, based on specimens collected at a fish market in Sanya, Hainan Island.

*Aurigequula* *striata*, left lateral view. (Photo credit: Jia-Jie Chen).

Live seafood markets have long proven to be unexpected hotspots for scientific discovery – just like the remarkable giant isopod Bathynomus vaderi described from market-purchased material in Vietnam.

As fresh as the seafood on display, this discovery was published in late January 2026 in ZooKeys. Newly collected specimens of Aurigequula fasciata enabled detailed morphological and genomic analyses, including the first complete mitochondrial genomes for both species and new phylogenetic insights into the family Leiognathidae.

*Aurigequula* *fasciata*, left lateral view. (Photo credit: Jia-Jie Chen).

Read more: ZooKeys 1267: 31–49. https://doi.org/10.3897/zookeys.1267.174380

Fittingly, we close with a horseshoe bat once feared lost. Its name bridges our equine theme with a traditional Chinese symbol: the word for bat (fú, 蝠) is a homophone for blessing (fú, 福), representing happiness and prosperity.

Hill’s horseshoe bat (Rhinolophus hilli), listed as Critically Endangered and unseen since 1981, was rediscovered in Nyungwe National Park, Rwanda, after 40 years.

*Rhinolophus* *hilli*, first observation of this species since 1981 in Nyungwe National Park. (Photo credit: Flanders, et al.).

Through cave surveys, forest capture efforts, and long-term acoustic monitoring, researchers confirmed the survival of this elusive species, bringing renewed hope for its conservation.

Read more: Biodiversity Data Journal 10: e83546 https://doi.org/10.3897/BDJ.10.e83546

As we gallop into 2026, may the Year of the Horse bring you strength, endurance, and a stable path toward success. On behalf of Pensoft, we wish you a happy, healthy and prosperous New Year!

Original sources:

Chen J-J, Zhong J-S, Zeng S, Yang D-Y, Liu P, Wang X-D, Zhang H-Y, Ye J-Q (2026) A new leiognathid record from China with complete mitogenomes and phylogenetic insights of two Aurigequula (Teleostei, Leiognathidae) species. ZooKeys 1267: 31-49. https://doi.org/10.3897/zookeys.1267.174380

Flanders J, Frick WF, Nziza J, Nsengimana O, Kaleme P, Dusabe MC, Ndikubwimana I, Twizeyimana I, Kibiwot S, Ntihemuka P, Cheng TL, Muvunyi R, Webala P (2022) Rediscovery of the critically endangered Hill`s horseshoe bat (Rhinolophus hilli) and other new records of bat species in Rwanda. Biodiversity Data Journal 10: e83546. https://doi.org/10.3897/BDJ.10.e83546

Heard J, Chen J-P, Wen CKC (2019) Citizen science yields first records of Hippocampus japapigu and Hippocampus denise (Syngnathidae) from Taiwan: A hotspot for pygmy seahorse diversity. ZooKeys 883: 83-90. https://doi.org/10.3897/zookeys.883.39662

Short G, Claassens L, Smith R, De Brauwer M, Hamilton H, Stat M, Harasti D (2020) Hippocampus nalu, a new species of pygmy seahorse from South Africa, and the first record of a pygmy seahorse from the Indian Ocean (Teleostei, Syngnathidae). ZooKeys 934: 141-156. https://doi.org/10.3897/zookeys.934.50924

Tiralongo F, Baldacconi R (2014) A conspicuous population of the long-snouted seahorse, Hippocampus guttulatus (Actinopterygii: Syngnathiformes: Syngnathidae), in a highly polluted Mediterranean coastal lagoon. Acta Ichthyologica et Piscatoria 44(2): 99-104. https://doi.org/10.3750/AIP2014.44.2.02

The Ghibli fish: new ‘painted’ species named after Princess Mononoke

The deepwater tilefish was first spotted by researchers on an online seafood market.

Picture in your mind the discovery of a new species.

What do you see? Researchers cutting through dense, untouched rainforests? Perhaps a submarine plunging into a deep-sea trench, illuminating a new world?

Well, it’s not always quite so dramatic. In fact, researchers in China discovered Branchiostegus sanae when they were scrolling through online seafood markets and noticed some deepwater tilefish with unique cheek patterns.

A tilefish with red and white facial markings. — *Branchiostegus sanae*. Credit: Huang et al.

These red-and-white facial markings reminded the research team of the Studio Ghibli character San from Princess Mononoke, whom they chose to honour in their naming of the species.

Published in the open-access journal ZooKeys, Branchiostegus sanae is a deepwater tilefish belonging to the family Branchiostegidae. Researchers confirmed its new-species status using genetic analysis, and chose “sanae” as the specific epithet (that’s the part that differentiates species within a genus), in a nod to Hayao Miyazaki’s animated creation.

Tilefish with red and white facial markings for sale at a seafood market. — *Branchiostegus sanae* at a seafood market. Credit: Jiangyuan Chen.

“Finding a new species in this group is a rare and fortunate event, especially one as distinctive as Branchiostegus sanae.

“In Princess Mononoke, San is a young woman raised by wolves after being abandoned by her human parents. She sees herself as a part of the forest and fights to protect it. The film delves into the complex relationship between humans and nature, promoting a message of harmonious coexistence between the two: something we hope to echo through this naming.”
Lead author, Haochen Huang.

The Chinese fishermen who sell the new-to-science species call it the“鬼马头鱼” (ghost horsehead fish), and this also contributed to the species name because, fittingly, “Mononoke” (もののけ) refers to supernatural spirits in Japanese folklore.

San, a warrior princess, from the animated film Princess Mononoke holding a spear. — San from *Princess Mononoke*. Credit: © 1997 Hayao Miyazaki/Studio Ghibli, ND.

As their name suggests, deepwater tilefish are found at great depths, with some species found 600 m below the surface. They are important food fish, commonly found in seafood markets in East and Southeast Asia.

Branchiostegus sanae is far from the only new species discovered at a seafood market. Indeed, a new giant isopod was recently dicovered in the same way – and also recieved a pop-culture inspired name. Check it out below!

The Dark Side of the ocean: New giant sea bug species named after Darth Vader

So far only 31 species are described in the family Branchiostegidae, and 19 species in the genus Branchiostegus. From 1990 to 2024, only three new species of Branchiostegus have been described.

Five tilefish species in a grid. — Other species of the genus *Branchiostegus* found in Chinese waters. Credit: Huang et al.

The study, led by researchers from the South China Sea Institute of Oceanology, Chinese Academy of Science, Zhejiang University and Ocean University of China, involved a combination of morphological analysis and genetic sequencing. Specimens were deposited in prestigious marine biological collections in China to facilitate future research.

Original study

Huang H, Chen J, Ke Z, Zhang C (2025) Branchiostegus sanae, a new species of deepwater tilefish (Eupercaria, Branchiostegidae) from the South China Sea. ZooKeys 1227: 129–142. https://doi.org/10.3897/zookeys.1227.130512

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The human dimensions of biological invasions – involving stakeholders in addressing invasive species

Can the knowledge and experience of recreational anglers in Iceland help us understand how far the invasive flounder has spread in the country?

Guest blog post by Theresa Henke

For centuries, all kinds of species have been transported by humans around the globe, allowing them to cross the boundaries of their native range and settle in new ecosystems. Over the past decades the numbers of these introduced species and the impacts they cause have been continuously increasing. Biological invasions nowadays represent one of the biggest threats to biodiversity worldwide.

Humans are and have always been an essential part of biological invasions and in order to fully understand the issue and how to tackle it, we need to understand and include the human dimensions in our research.

My research on European flounder in Iceland began in 2017 when I was writing my Master’s thesis. The flounder is a flatfish species that had been officially documented in the country since 1999 but not much was known on its impacts. In my thesis I looked at the flounder through ecological lenses, trying to identify how the presence of the flounder affects other species. Living in a small community in the Westfjords of Iceland during this time, I got to meet many local people who shared their personal stories, experiences and knowledge with me in every-day conversations. I truly enjoyed these conversations and learning about the species I study from different perspectives beyond the academic settings. These exchanges sparked my interest in exploring the human dimensions of biological invasions and, looking back, have really shaped my academic path going forward.

In our recently published NeoBiota study “Have you seen this fish? – Important contribution of stakeholder observations in documenting the distribution and spread of an alien fish species in Iceland” we wanted to explore how the knowledge and experience of recreational anglers in Iceland can help us understand how far the flounder has spread in Iceland. The flounder in Iceland had only received little scientific interest before and the available information was limited and scattered between different institutions and scientists. Recreational anglers, on the other hand, who chase after native salmon, trout, and char in the Icelandic rivers and lakes, often encounter the flounder.

In 2019, we asked anglers in Iceland to take part in an online survey, where we asked them different questions about the flounder, including where in Iceland they have seen or caught it. We then compared locations named by anglers to the locations that were available from different databases of the Marine and Freshwater Research Institute of Iceland. The locations we received included data collected during scientific surveys and research projects done by the institute as well as observations that were reported to the institute by the public (mostly recreational anglers and commercial fishermen).

Our goal was to evaluate whether observations made by stakeholders, in this case the recreational angling community in Iceland, could be a good source of additional information for monitoring of an alien fish species. Collecting information on the distribution and spread of an alien species is a very important step in addressing biological invasions but is often underdeveloped because not enough resources (i.e. money, time, scientists…) are made available.

Theresa Henke holding a 43-cm flounder in Eyjafjörður.

We have shown that neither source offers a perfect solution to the monitoring of the flounder in Iceland. But we show that each of the sources has their own advantages and disadvantages and by combining them, we are able to get a much clearer picture of where in Iceland the flounder currently occurs and how fast it spread in the early years. Information that was shared by stakeholders, whether it was in our study or to the databases of the Marine and Freshwater Research Institute, played a big role in better understanding the flounder in Iceland.

The interactions with the recreational angling community in Iceland during my PhD have taught me a lot about the flounder in Iceland but even more about my own approach to science. I think as scientists, we should more often take a step outside of our academic bubble and take a look at the issue we are studying from the perspectives of the public and other stakeholders. In the case of biological invasions, we can learn a lot from those who are directly confronted by an invasive species, regardless of whether they have a scientific degree or not.

Research article:

Henke T, Bárðarson H, Thorlacius M, Ólafsdóttir GA (2025) Have you seen this fish? Important contribution of stakeholder observations in documenting the distribution and spread of an alien fish species in Iceland. NeoBiota 97: 67-90. https://doi.org/10.3897/neobiota.97.132365

New ‘grumpy’ fish species discovered in the Red Sea

Found among coral reefs in the Red Sea, it has large canines and a fierce expression, even though it is only 2 cm long.

A team of researchers at the King Abdullah University of Science and Technology and the University of Washington has discovered a new species of fish that seems perpetually displeased. The researchers decided to call this new species the grumpy dwarfgoby.

Despite its small size of less than 2 centimeters, the grumpy dwarfgoby has a surprisingly menacing appearance. Its large canines and fierce expression give it a rather intimidating look for such a small fish.

Lucía Pombo-Ayora, who gave the species its grumpy common name, comments on its distinctive appearance: “I imagine in its own tiny world, it is a fearsome predator. Its grumpy expression and large canines certainly make it look the part, despite its small size.”

A CT scan image of the skull of a grumpy-looking fish.

The species’ bright red coloration actually helps it blend into its natural habitat. It can be found on the walls and overhangs of coral reefs, covered in red coralline algae. There, it lives in small holes and crevices, using its large canines to capture tiny invertebrates. The grumpy dwarfgoby appears to be a relatively rare species, which is likely why it remained undiscovered until now.

The researchers found the first specimens in the Farasan Banks in Saudi Arabia, with additional specimens later found near Thuwal in the Red Sea. It was researcher Viktor Nunes Peinemann who first found it during a diving expedition to explore the coral reef fish diversity. Initially, the researchers thought they had rediscovered the fiery dwarfgoby, Sueviota pyrios, which is only known from a single specimen collected in 1972. However, upon closer examination, they realized they were dealing with an entirely new, undescribed species.

A photograph of a translucent-red grumpy-looking fish on a black background.

“The ongoing discovery of distinctive new species like this grumpy dwarfgoby shows how much biodiversity remains undiscovered in the Red Sea,” Viktor Nunes Peinemann explains. “This is concerning given the recent environmental changes in the region. In some cases, species could go extinct before we even describe them.”

The region is known for its high levels of endemic species and the Grumpy dwarf goby is another addition to this unique fauna. Much of the Red Sea has experienced major disturbances resulting from climate change in recent years, including widespread coral bleaching and mortality. The fact that new species are still being discovered in this rapidly changing environment highlights the urgency of continued research and conservation efforts, the researchers believe.

They have published their discovery in the open-access scientific journal ZooKeys.

Photos by Viktor Nunes Peinemann

Research article:

Nunes Peinemann V, Pombo-Ayora L, Tornabene L, Berumen ML (2024) The Grumpy dwarfgoby, a new species of Sueviota (Teleostei, Gobiidae) from the Red Sea. ZooKeys 1212: 17-28. https://doi.org/10.3897/zookeys.1212.121135

New species, old threats: two hillstream suck-loaches discovered in China

The new-to-science fish face an uncertain future due to pollution and unsustainable harvesting.

All too often, researchers discover new species only to learn they are already at risk of extinction.

So when researchers from Shanghai Ocean University and Yunnan Agricultural University identified two new species from the upper Pearl River system in southwest China, they were likely unsurprised to find the fish facing major threats from pollution and overharvesting.

Three views of a flat-bottomed fish species with bumps on its head. — *Beaufortia* *granulopinna* holotype from Lizhou River, a stream tributary of Bo′ai River of the Pearl River basin, at Tianlin County, Guangxi Province, China.

The new species, Beaufortia granulopinna and Beaufortia viridis, are members of the family Gastromyzontidae, also known as hillstream suck-loaches. They are highly specialised, with compressed bodies, flattened bottoms, and greatly expanded paired fins forming suction cup-like structures. These adaptations enable them to adhere to rocky substrates, resisting currents while feeding on algae and invertebrates.

Researchers discovered the new species during surveys studying aquatic life in various waterways in Yunnan and Guangxi between 2022 and 2024. The study, led by Jing-Chen Chen, offers new insights into the taxonomy and molecular phylogeny of the Beaufortia pingi species group, of which the two discoveries are likely members.

Three views of a flat-bottomed fish species witha green and brown colouration. — *Beaufortia* *viridis* holotype from Wuming River, a stream tributary to the You River of the Pearl River basin, at Wuming District, Nanning City, Guangxi Province, China.

Although research on the Beaufortia pingi group is mostly in its initial stages, the situation is far from optimistic. These species have become popular ornamental fish in China, and aquarium trade operators reap substantial profits through their capture and sale. Among them are those who act with disregard for sustainability, using destructive harvesting practices.

Given the loaches’ preference for fast-flowing water, projects that obstruct rivers can easily lead to regional extinction. Their low pollution tolerance and sensitivity to changes in water quality also contribute to the significant reductions in population that many species are suffering.

Landscape image of a river and trees. — Collection site of *Beaufortia* *viridis* from Wuming River, a stream tributary to the You River of the Pearl River basin, Wuming District, Nanning City, Guangxi Province, China. Photographed by Jing-Chen Chen.

In the habitat of B. viridis, Wuming District, Nanning City, most small tributaries have been modified into step-like reservoirs for water storage, and those near agricultural irrigation areas are polluted, rendering these areas unsuitable for their survival. Interestingly, however, a stable population was discovered inside a commercial eco-camping site left untouched to satisfy consumers’ pursuit of “pristine nature.”

The researchers suggest that future efforts should focus on increasing attention to these species, conducting fundamental research, and further exploring their scientific and economic potential. Simultaneously, it is crucial to enhance habitat conservation awareness, scientifically plan, and develop sustainably, ensuring harmonious coexistence between humans and nature.

Original source

Chen J-C, Li J-J, Tang W-Q, Pu X-R, Lei H-T (2024) Taxonomic resolution of the hillstream suck-loach Beaufortia pingi species group (Cypriniformes, Gastromyzontidae) and two new species from Southwest China– Beaufortia granulopinna and Beaufortia viridis. Zoosystematics and Evolution 100(3): 941-963. https://doi.org/10.3897/zse.100.124370

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Microplastic contamination of Black Sea fish threatens marine ecosystems

Five commercially important fish species from the Bulgarian Black Sea coast were found to be contaminated with microplastics.

Guest blog post by Stephany Toschkova, Sevginar Ibryamova, Darina Ch. Bachvarova, Teodora Koynova, Elitca Stanachkova, Radoslav Ivanov, Nikolay Natchev, Tsveteslava Ignatova-Ivanova

One of the main problems of the world’s oceans, reported by many scientific studies, is microplastic pollution. It is also one of the main sources of pollution in the Black Sea. Our new study in BioRisk details microplastic contamination in five fish species important for commercial fishing (Garfish, Мullet, Knout goby, Pontic shad, and Mediterranean horse mackerel). The fish were collected from the Sozopol area of the Bulgarian Black Sea coast.

Mediterranean horse mackerel. Photo by Donald Davesne
Knout Goby. Photo by Aleksandr_Levon
Мullet. Photo by Roberto Pillon

Our results show a wide variety of micropollutants originating from commonly used items such as plastic cups, stirrers, bags, soft drink bottles, fishing nets, packaging, аnd personal hygiene products. These objects systematically enter the Black Sea and degrade into microplastic particles. Microplastics (MPs) were found in all studied tissues of the fish in the form of pellets, fibers and fragments. Pellets were found most frequently, followed by irregularly shaped fragments, while fibers were the least numerous.

Stereomicroscope picture of morphological types of microplastics (arrowheads) recognized in the studied specied from: A) Garfish; B) Mullet C) Pontic shad and D) Mediterranean horse mackerel.

The bulk of the isolated plastics are made of polyethylene (PE) and polyethylene terephthalate (PET). PE is found in plastic bottles, cups, stirrers, and plastic bags. This polymer is very light and floats on the surface of the sea because its density is lower than that of water. PET, on the other hand, is denser than water and more likely to sink and accumulate in it and in organisms living on the seafloor. These polymers are widely used in fabrics, nets, ropes, and strings used for fishing, one of the main economic activities in the Black Sea. The predominant polymer type, PE, corresponds to the content of manufactured plastics all around Europe, as almost half of the plastics produced in Europe are reported as PE.

The sinking and sedimentation of plastics relate to the fact that the upper layer of the Black Sea is less dense than that of other seas. Furthermore, the weight of these particles increases due to the accumulation of marine plants and nutrients on them, and this can affect the distribution of plastics and their sedimentation on the seabed.

A satellite image of the Black Sea. Photo by NASA/GSFC/MODIS

Judging by the obtained results and the amount and type of polymers found in the study and the literature, the source of contamination, in our opinion, can be mainly attributed to domestic wastewater discharges coming from the washing of synthetic fabrics. In Bulgaria, wastewater is discharged – directly or after purification – into marine and freshwater ecosystems, as is the case in other neighbouring countries along the Black Sea coast. However, detailed studies are needed to prove this hypothesis.

Considering the wide variety of MP types detected in the digestive tracts of the fish, we assume that they regularly ingested MPs during feeding. Many nutrients are also held on the plastic particles, which deceives the fish into perceiving them as food.

microplastics under a microscope — Microplastics under a microscope. Photos by GTM NERR

Microplastics under a microscope. Photos by GTM NERR

It has been reported that plastics smaller than 1000 μm can reach the digestive tract or the gills of fish, and in turn can cause adverse effects such as a weak immune response or reduced fertility.

MPs can also accumulate in predatory fish species. Unfortunately, very limited research was performed on bioaccumulation and biomagnification in food webs, therefore more studies are needed to reach this conclusion.

MPs enter seawater food chains in different pathways and threaten entire ecosystems through their ability to transport pollutants, pathogenic microorganisms, and alien species. Bearing in mind the intensifying economic activity on the Black Sea coast and the consequent influence on the riverine water quality, river mouths can be considered potential sources of MPs. Particularly concerning is the area near the Kamchia River mouth, which is the biggest intra-territorial river in Bulgaria, entering directly into the Black Sea, with a catchment area of more than 5 300 km². This catchment and the entire Black Sea coast, where agriculture is well developed is a potential source of MPs, which have the ability to absorb and release toxic chemicals of organic and inorganic origin such as bisphenol A, PCBs and DDT, creating an additional potential risk to human health.

A satellite image showing the Kamchia River mouth.

Humans are exposed to BPA in the environment they live in, from the air we breathe to the food and drinks we consume. So, even if BPA intake is below accepted limits, this does not guarantee that the additive will not accumulate and cause more pronounced effects and chronic toxicity in the food chain, given its tendency to accumulate.

It is important that future research determines the toxicological side effects of plastic ingestion for fish communities in both benthic and pelagic habitats. However, even if we stop introducing plastics into the water system, both groups of fish will continue to be impacted, since the number of microplastics can increase due to the breakdown of larger plastics in the environment.

Invasive species as biomonitors of microplastics in freshwater ecosystems?

This study shows the need to carry out further studies of microplastics using different types of microscopic and spectral analysis. Even though microplastics may not pose a risk to humans who consume fish, these contaminants pose a potential risk to marine food webs and endangered species. We found particles of different sizes, types and colours in different fish species, and believe the variability of polymer types in fish can indicate the polymer types in water to some extent. Our results show that fish are important as ecological bioindicators and serve as a basis for future studies on microplastic pollution in tourist sandy beaches.

Research article:

Toschkova S, Ibryamova S, Bachvarova DCh, Koynova T, Stanachkova E, Ivanov R, Natchev N, Ignatova-Ivanova T (2024) The assessment of the bioaccumulation of microplastics in key fish species from the Bulgarian aquatory of the Black Sea. BioRisk 22: 17-31. https://doi.org/10.3897/biorisk.22.117668

Fourteen years after the Gulf of Mexico oil spill, endemic fishes face an uncertain future

A study investigating the spill’s impact on endemic fish species suggests potential loss of biodiversity.

The 2010 Gulf of Mexico Deepwater Horizon was the largest accidental oil spill in history. With almost 100 million gallons (379 million liters) of oil combined with dispersants suggested to remain in the Gulf, it is one of the worst pollution events ever. More than a decade later, its long-term effects are still not fully understood.

A ship sails among spilled oil in the Gulf of Mexico after the BP Deepwater Horizon oilspill disaster. Photo by Kris Krug shared under a CC BY-NC-SA 2.0 license.

In a new study, researchers from Louisiana State University and Tulane University examined the endemic Gulf of Mexico fish species that may have been most impacted by the oil spill to see how their distribution has changed over the years. To get their data, they studied museum specimens from natural history collections, looked at relevant literature, and combed biodiversity databases.

Lead author Prosanta Chakrabarty in the fish collections of the Louisiana State University Museum of Natural Science, where many specimens from the Gulf of Mexico are housed. — Lead author Prosanta Chakrabarty in the fish collections of the Louisiana State University Museum of Natural Science where many specimens from the Gulf of Mexico are housed. Photo credit: Eddy Perez, LSU

With 1541 fish species known from the region, and 78 endemic fish species, the Gulf of Mexico is one of the most biologically rich and resilient marine environments in the world, but how much of this diversity is still left intact?

The study found that 29 out of the Gulf’s 78 endemic fish species haven’t been reported in museum collections since 2010. The Yucatan killifish, for example, which is considered endangered, was last reported pre-spill, in 2005, off the Yucatán Peninsula.

Six of the non-reported species are considered of greatest concern, because their areas of distribution largely overlap with the affected area – although the authors note that their absence in the Gulf in recent years cannot automatically be attributed to the oil spill.

Jars of voucher specimens of fishes at the Louisiana State University Museum of Natural Science. Photo credit: Eddy Perez, LSU

“Understanding the impacts of catastrophic environmental events such as the 2010 Gulf of Mexico Oil Spill does not end when the wellhead is capped or when the last drops of oil cease to flow. The disaster only begins to end when the data no longer show impacts of the event. We are far from the beginning of the end for the Deepwater Horizon Oil Spill. Lingering chemicals, lost generations of wildlife and a continued ecosystem imbalance may all be factors that prevent an environment from rebounding from such cataclysmic events,” the authors note in their research article.

However, they also point out that nature’s ability to recover should not be overlooked.

“The Gulf of Mexico continues to face many challenges, from the Dead Zone, to climate change, loss of coast habitats and continued oil spills. Efforts like this report aim to bring attention to vulnerable species that continue to be impacted by human activities and to the unique endemic fauna of the region,” the researchers write in conclusion.

Research article:

Chakrabarty P, Sheehy AJ, Clute X, Cruz SB, Ballengée B (2024) Ten years later: An update on the status of collections of endemic Gulf of Mexico fishes put at risk by the 2010 Oil Spill. Biodiversity Data Journal 12: e113399. https://doi.org/10.3897/BDJ.12.e113399

NOAA Fisheries Zoologist Describes New Fish Species

Dr. Katherine Bemis of the National Systematics Laboratory recently helped describe a new species of fish, the papillated redbait.

New species alert! Dr. Katherine Bemis of NOAA Fisheries’ National Systematics Laboratory and her collaborators recently described a new fish species: Emmelichthys papillatus, or the papillated redbait. Its discovery was published in the journal ZooKeys.

The papillated redbait is a member of the family Emmelichthyidae. There are only 18 known species in this family, which are commonly called redbaits, rovers, or rubyfishes. These deepwater species can be found in warm, tropical waters and are usually bright shades of red, orange, and pink.

How did Bemis and her team make this remarkable discovery? To find out, we’ll have to first travel to a fish market in the Philippines.

A molecular mystery

As part of an interagency campaign to create a reference library of fish DNA “barcodes,” Bemis and her colleagues regularly travel abroad to collect fish specimens. Some come from seafood markets overseas where they are being sold for food. In the field, these new specimens are assigned a preliminary species identification. Then, they’re transported to the Smithsonian Institution and National Systematics Laboratory for genetic sequencing, data collection, and a secondary species confirmation.

Dr. Katherine Bemis holds the holotype–the specimen upon which a new species’ description is based–of the papillated redbait. Credit: Haley Randall/NOAA Fisheries

Since getting involved with this project in 2021, Bemis and teammate Dr. Matthew Girard of the Smithsonian National Museum of Natural History have analyzed thousands of samples. None have made a bigger splash, though, than two small pink fish collected from a Philippine fish market on the island of Cebu.

While collecting data from these specimens, Girard made an exciting observation. Their genetic sequences did not match their initial species identification as golden redbaits—or any other species in the genetic library, for that matter. So which species did Girard and Bemis have on their hands?

Dr. Matthew Girard examines the holotype of the papillated redbait under a microscope. Credit: Dr. Katherine Bemis. Source NOAA Fisheries

In search of answers, Bemis and Girard examined other aspects of the specimens’ biology, including their anatomy. They discovered that these fish differed from the golden redbait in several ways, including:

A different number of gill rakers, structures inside the mouth that help fish to feed
A different number of pectoral fin rays
Two fleshy structures called papillae on the pectoral girdle

These differences, combined with the genetic data, provided evidence that the two specimens were not golden redbaits, but a previously undiscovered species. With only two confirmed specimens, Bemis and Girard wondered if other individuals could be identified in global natural history collections.

Underneath the gill cover, you can observe the two characteristic papillae (singular: papilla) of the papillated redbait labeled with arrows (left). The closely-related golden redbait lacks papillae in the same area (right). Photos courtesy of Dr. Matthew Girard. Source NOAA Fisheries

After some detective work, Bemis and Girard spotted a third specimen they hypothesized might also be the undescribed species. A fish with similar color also identified as a golden redbait had been collected from a fish market in the Philippines by the Kagoshima University Museum in Japan. Bemis and Girard studied the specimen and confirmed their hypothesis with genetic and anatomical data. This specimen became the third record of papillated redbait and, ultimately, the holotype for the species—the specimen upon which a new species description is based.

More to discover

Even after describing new species, there’s always more to learn. Bemis and Girard are energized that there is still much to discover about the papillated redbait and the redbait family, which is relatively poorly known. Any opportunity to add to this small body of knowledge and study redbait species in greater detail is valuable. “I’ve had researchers that work on fish taxonomy say to me, ‘I didn’t even know this family existed.’ That’s how little we know about this group,” Girard emphasizes.

Bemis also notes that because data on the papillated redbait comes from only three specimens purchased in fish markets, she still has lots of questions. For example, Bemis says that they don’t yet know if the new species occurs outside Philippine waters, or the exact habitat in which they occur. “We also don’t know anything about their reproduction or what they eat—really basic aspects of their biology remain to be studied. Now that we recognize that it is different, we only have more to study as new specimens of papillated redbait are collected,” Bemis says.

“It is always a happy and productive moment working with U.S. scientists,” says Dr. Mudjekeewis “Mudjie” Santos of the Philippine National Fisheries Research and Development Institute. Santos was instrumental in the collection of specimens, providing fisheries data on the papillated redbait, and coining a name for the new species in Tagalog, the national language of the Philippines. Here, he examines fish in a Philippine market. Photo courtesy of Dr. Mudjekeewis Santos. Source NOAA Fisheries

One thing is for certain, though. There are more species just waiting to be discovered, and they might be right under our noses. “I think the craziest thing is that the papillated redbait is a new species that came from a market,” Girard says. “The fact that there are undescribed species being sold without us even realizing it underscores how much we still have to learn about marine biodiversity.”

Research article:

Girard MG, Santos MD, Bemis KE (2024) New species of redbait from the Philippines (Teleostei, Emmelichthyidae, Emmelichthys). ZooKeys 1196: 95-109. https://doi.org/10.3897/zookeys.1196.111161

This story was originally published by NOAA Fisheries. It is republished here with their permission.

AI-powered data-limited stock assessment method more accurate than ‘gold standard’ in predicting sustainable fisheries catches

A recent update introduced to the CMSY methodology used to assess the status of fish stocks has proven to more accurately predict the catch that a population can support than highly valued data-intensive models.

Article provided by Valentina Ruiz, Sea Around Us.

In a paper published in the journal Acta Ichthyologica et Piscatoria, the international team of researchers that shaped the improved CMSY++ model noted that its results better correspond with what is, in reality, the highest catch that a fish stock can support in the long-term, given that environmental conditions do not change much.

Now powered by an artificial neural network that has been trained with catch and biomass data of 400 stocks to identify plausible ranges of the initial and final state of the stocks being assessed, CMSY++ allows managers and scientists to input only catch data to estimate how much fish is left in a given stock and how much fishing pressure can be applied.

CMSY model — Schematic representation of the surplus production model used by CMSY, with indication of impaired recruitment due to small stock size, where FMSY is reduced linearly with decline in biomass.

Maximum sustainable catches or yield (MSY) is a concept developed in the 1950s by US fisheries scientist M.B. Schaefer who proposed that if fishers left in the water a biomass equivalent to at least 50 per cent of the unexploited fish population, that is, of the biomass it had before being commercially exploited, then the highest possible catches could be sustained over time.

“By comparing the results of CMSY++ to models that are considered superior because they require large amounts of initial data inputs, such as the Fox surplus-production model and the Stock Synthesis (SS3) age-structured model, we noticed that these models badly overpredicted the catch that a population can support when previous overfishing has reduced it to a small fraction of its natural size, as is the case with most exploited fish populations in the world.”
Dr. Rainer Froese, lead author of the study and a senior scientist at the GEOMAR Helmholtz Centre for Ocean Research.

In other words, the model underlying the CMSY++ method fitted the observed data, while the predictions of the ‘gold standard’ models were too optimistic in estimating sustainable catches.

“These models tend to estimate the biomass required to produce maximum sustainable yields as less than half of unexploited biomass, which is lower than M.B. Schaefer originally proposed based on the widely observed S-shaped growth curve of unexploited populations or population size that the ecosystem would normally accommodate.

“This finding could explain the often-observed failure of fisheries managers to maintain or rebuild depleted stocks even when the predictions of the gold standard models were followed.”
Daniel Pauly, co-author of the study and principal investigator of the Sea Around Us initiative at the University of British Columbia.

Research article:

Froese R, Winker H, Coro G, Palomares MLD, Tsikliras AC, Dimarchopoulou D, Touloumis K, Demirel N, Vianna GMS, Scarcella G, Schijns R, Liang C, Pauly D (2023) New developments in the analysis of catch time series as the basis for fish stock assessments: The CMSY++ method. Acta Ichthyologica et Piscatoria 53: 173-189. https://doi.org/10.3897/aiep.53.e105910