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NMFRI Gdynia Aquarium

Akwarium Gdyńskie

  • Arowana srebrna

    Arowana srebrna

    Rząd: Osteoglossiformes (kostnojęzykokształtne)

    Rodzina: Osteoglossidae (kostnojęzykowe)

    Osteoglossum bicirrhosum (Cuvier, 1829)

    Fot. Dominik Paszliński

    Ryba ta występuje w słodkich wodach Ameryki Południowej, a konkretnie w dorzeczach Amazonki, Essequibo i Oyapock. Zasiedla zarówno rzeki białe (o wodach bogatych w substancje mineralne), jak i czarne (z woda o bardzo niskim odczynie pH i dużej zawartości kwasów huminowych i fulwowych). W porze suchej zamieszkuje wolno przemieszczające się lub nieruchome dopływy, rozlewiska i laguny, zaś w porze mokrej przemieszcza się na obszary zalewowe. Ze względu na swoje drapieżne zachowania preferuje płytsze wody. Jest w stanie przystosować się do środowiska o niskim poziomie tlenu rozpuszczonego w wodzie. Używają wówczas swojego pęcherza pławnego jako dodatkowego narządu oddechowego.

    Wygląd

    Arowana osiąga długość wynoszącą 90 cm, chociaż są doniesienia o osobnikach dorastających do 1,2 m. Maksymalna udokumentowana waga wynosiła 6 kg. Jej wydłużone ciało pokryte jest bardzo dużymi, zdobionymi łuskami, skierowany ku górze pysk jest zwieńczony 2 kolcami, zaś płetwa grzbietowa i odbytowa rozciągają się praktycznie od połowy długości ryby, aż do płetwy ogonowej. Ubarwienie zmienia się wraz z wiekiem ryby. Na ciele osobnika młodocianego widoczne są niebieskie refleksy oraz żółto-pomarańczowy pasek, zaś osobnik dojrzały jest srebrzysty. Cechą charakterystyczną jest jej kościsty język, który jest pomocny w chwytaniu ofiary. Ponadto wiele elementów jamy ustnej zaopatrzonych jest w zęby, w tym szczęka, podniebienie, język oraz gardło.

    Odżywianie

    Jest to ryba wszystkożerna, która żeruje na powierzchni. Pozycja jej otworu gębowego pozwala jej chwytać zdobycz od dołu. Ma wyjątkowe zachowania drapieżne. Pozostaje blisko brzegu i czeka na przepływającą ofiarę. Zwykle ustawia się bokiem przy powalonym drzewie, wówczas jest mniej widoczna. W trakcie ataku potrafi wyskoczyć ponad powierzchnię wody. To szczególne zachowanie przyniosło jej przydomek „małpy wodnej” lub „ryby małpy”. Pomimo tego, że jej główną dietę stanowią owady, mięczaki, skorupiaki, mniejsze ryby i inne zwierzęta unoszące się na powierzchni wody, w jej żołądku znajdowano również szczątki ptaków, nietoperzy i myszy.

    Rozmnażanie

    Arowana jest gatunkiem rozdzielnopłciowym z tarłem odbywającym się na początku pory mokrej, czyli w grudniu i styczniu. W ciągu całego sezonu lęgowego samica jest w stanie wyprodukować od 50 do 250 jaj, zaś typowa wielkość pojedynczego lęgu wynosi od 12 do 30. Rola samicy ogranicza się do złożenia jaj. Opiekę nad potomstwem przejmuje samiec, który najpierw jaja, a później larwy i osobniki młodociane przenosi w swoim pysku. Narybek jest zwykle dość duży i już po wylęgu ma długość 50-75 mm. Młode przebywają w pysku samca do momentu wchłonięcia się ich woreczka żółtkowego, czyli około 2 miesięcy. W tym czasie rybacy wyławiają samce, wyjmują młode i przeznaczają je na sprzedaż. W handlu bardzo często dostępne są młode z widocznym woreczkiem żółtkowym.

    Znaczenie gospodarcze

    Wspólne korzystanie z zasobów populacji arowany srebrnej mieszkańców Brazylii i Kolumbii było przyczyną sporu między władzami w 2005 roku. Kolumbijczycy pozyskiwali młode arowany do sprzedaży jako ryby akwariowe, zaś mieszkańcy brazylijskiej Amazonii łowili dorosłe ryby na pożywienie. Spowodowało to gwałtowny spadek liczebności arowany. Wprowadzono zakazy połowów w Brazylii od 1.09. do 15.11., zaś w Kolumbii od 1.11. a 15.03. Arowana ma dużą wartość gospodarczą dla miejscowej ludności. Stanowi największe źródło białka w porównaniu z innymi rybami amazońskimi. Ponadto, ze względu na niską zawartość tłuszczu, jest uważana za najbardziej strawną i najmniej podatną na choroby. Mieszkańcy Coboclo z Amazonii uważają ją za jedyny dopuszczalny pokarm dla kobiet w okresie połogu. Arowana ma również wielką wartość w branży akwarystycznej, o czym świadczy jej sprzedaż na wielu komercyjnych stronach internetowych oraz ceny jakie osiąga. Jest to jednak najtańszy spośród wszystkich gatunków arowan. Okaz znacznie rzadszej arowany azjatyckiej został sprzedany za 300 tysięcy dolarów. Kostnojęzykowe to jedyna rodzina ryb słodkowodnych, której przedstawiciele żyją po obu stronach Linii Wallace’a, z czterema ważnymi gatunkami w Ameryce Południowej, jednym w Afryce, jednym w Azji Południowo-Wschodniej i dwoma w Australii.

    Czy arowana może przetrwać w wodach Polski?

    W 2016 roku zaobserwowano pojedynczego przedstawiciela arowany srebrnej w Jeziorze Powsinkowskim. Osobnik ten miał 40 cm długości i był w kiepskiej kondycji. Jego ciało było poranione, najprawdopodobniej po atakach innych ryb. Nie ma szans, aby przetrwał on w zbiornikach słodkowodnych Polski, ze względu na niską temperaturę w nich panującą.

  • European flounder

    European flounder

    Platichthys flesus

    Order: Pleuronectiformes | Rodzina: Pleuronectidae

    This flat fish inhabits European coastal waters, ranging from the Barents Sea and the White Sea, through the Norwegian Sea, the North Sea, the Baltic Sea, and the Bay of Biscay, to the Mediterranean Sea. It was introduced to the United States and Canada by pure chance, probably through transport in ballast water. Although it is a sea species, it can also be found in salt waters and up rivers, where it lives near the bottom at depths of up to 100 m. It is a nocturnal species that buries itself in sand during the day to wait for prey or hide from predators.

    Appearance

    Adults of the species typically grow up to 50 cm in length, although they can reach up to 60 cm and weigh up to 14 kg. The European flounder found in the Baltic Sea is much smaller, reaching around 35 cm in length and living from 8 to 9 years. The flounder has an asymmetrical and heavily flattened oval-shaped body, with a height that is half of its length. As this fish swims and lays on its side, we cannot discern a dorsal and pelvic side when we talk about its coloration. Therefore, we have to describe the visible top and bottom parts. The top is dyed with colors ranging from olive to deep brown with red and brown spots, depending on the habitat. The bottom side is always white. This fish can change its coloration to blend in. For example, flounders at sea bottoms with rocks will be darker than those at sea bottoms made entirely out of sand. Its body is covered in scales, some of which are rough bone plates, especially sharp along the lateral line and at the base of its odd fins. This distinguishes the European flounder from other plaice. Its small mouth limits its diet to small organisms.

    Sustenance

    The European flounder looks for food near the sea bottom above which it swims, comprising of polychaetes, mollusks, snails, crustaceans, and small fish. The juveniles, which are planktonic, eat plankton and the larvae of insects. It is a gonochoristic animal, reaching sexual maturity at the age of three. Individuals that spend their summer in fresh waters start their journey to the open sea in the fall to spawn. Spawning takes place in very salty waters, at temperatures between 3 and 7°C, and at a depth of 30 to 300 meters. In the southern part of the Baltic Sea, the spawning occurs from March to May and takes place in the Słupsk Furrow and the depths of the Gdańsk and Bornholm Basins, and coś Arkońskiego. The female lays from 100,000 to 2 million grains of roe, which float on the surface. Hatching is dependent on the temperature and takes place during the 5th and 11th day of the laying. The larvae’s length after hatching is around 3 mm, and its body is symmetrical. The transformation begins when it reaches 7 mm. The juveniles migrate to the shallows and up rivers. The flounder is an important species in the fishing industry and is valued for its meat. It can also be found in aquariums. The P. flesus species has six discernible subspecies, depending on the habitat. These are the nominative subspecies (upon which the European flounder was first described), White Sea, Northern, Baltic, Mediterranean, and Black Sea flounder.

    Flounder – a fish with eyes on one side

    The larva of this fish is symmetrical after hatching. Its body begins to transform when it reaches a length of 7 mm, and the eye starts its journey. By the time a juvenile reaches a length of 1 cm, one of its eyes is already in the middle of its head. The eye moves simultaneously with the fish’s growth and eventually nears the second eye. The symmetry of the fish’s body changes at the same time as the eye’s journey. Initially, the larva moves like any other fish, with its back up. However, over time, the symmetry shifts either to the right or left, and ultimately, the juvenile swims and lies on its side. In 70% of the cases, the left side becomes the bottom side, which means that both eyes are on the right side. Although plaices are distinguishable from other fish today, they probably evolved from forms similar in shape to modern Percidae fish. Their ancestors had symmetrical bodies, which is evident from the presence of symmetrical larvae that undergo an extraordinary transformation.

  • Butterflyfish

    Butterflyfish

    Order: Perciformes

    Family: Chaetodontidae (butterflyfish)

    Chaetodon falcula

    In the Chetonidae family, 132 species of fish were distinguished, belonging to 12 different genera, most of them included in the genus Chaetodon. These animals are associated with the tropical waters of the Pacific, Atlantic and Indian Oceans. Some also prefer warm temperate waters. The greatest diversity and abundance of Chetonidae is found in the Indo-West Pacific, from Australia to Taiwan. Only 4 species are found in the eastern waters of the Pacific Ocean and 13 species in the Atlantic Ocean.

    Habitat

    These fish are closely related to coral reefs. They can also live among seagrass, in deep muddy plains or in shallow lagoons. Juveniles of many species inhabit areas other than mature ones, such as tidal basins, rock reefs, and shallow coral-free areas. Chaetodontidae are most commonly found in shallow waters below 20 meters deep, but some species are seen at depths around 200 meters. Although they are typically marine animals, some are also found in brackish waters of estuaries.

    Life

    These animals move around the reef very actively during the day and then forage, while at night they hide in crevices and change their coloration to a more subdued one. They usually live in pairs. Fish that eat zooplankton form herds, while juveniles are loners. The body size of the fish varies depending on the species between 9 and 22 cm in length. The largest species, such as the Lined butterfly (Chaetodon lineolatus) and the Saddle butterflyfish (Chaetodon ephippium), can grow up to 30 cm in length. Sources do not provide specific information on the lifespan of these fish. On the basis of information that they reach sexual maturity after one year, it can be concluded that most species live for at least 3 years.

    Appearance

    Forcipiger flavissimus

    The English name of this family “butterflyfish” refers to butterflies, due to brightly colored and patterned bodies of many species, in shades of black, white, blue, red, orange and yellow. Many of them have eyelets on the sides of the body and dark streaks over the eyes, much like the patterns seen on butterfly wings. Their clear coloration can be used for interspecies communication. Although they differ significantly in color, they have some common features. They all have a deep, laterally flattened body. They look almost round from the side. Their dorsal and caudal fins are continuous, emphasizing the oval shape of the fish’s body. The scales covering the body also overlap the dorsal and anal fins. Their pointed snouts are tipped with tiny mouth armed with toothbrush-like teeth. The degree of elongation of the mouth depends on the food consumed. Some species, such as the Forceps butterflyfish (Forcipiger flavissimus), have extra-long tweezers-like jaws that can pick invertebrates from narrow slits. Others, such as the Ornate butterflyfish (Chaetodon ornatissimus), have short jaws for picking live coral polyps. The jaws of some butterflyfishes may account for more than 25% of the body length of a fish.

    Feeding

    Many species feed on small invertebrates, sponges, fish eggs, thread algae, and others on zooplankton. Some species only feed on coral polyps. Species that feed on algae growing on corals contribute to their protection by removing competing species that take away the light access.

    Reproduction

    They are dioecious, but there is no obvious sexual dimorphism. They are animals that form monogamous pairs. Most species stay with the same mate for several years, while some species mate for life. Couples accompanied by a juvenile were occasionally observed. This suggests that the young are asexual or capable of maturing into a male or a female, depending on the needs. However, this information has not been confirmed. Based on data collected for several species, it has been found that the spawning season in tropical waters peaks in winter and early spring, while species in temperate areas reproduce in the middle of summer. Some groups reproduce all year round. Spawning usually takes place at dusk. The male swims behind and under the female, poking her with his mouth in a belly filled with eggs. The release of gametes (eggs and sperm) takes place in the water column about 10-15 meters above the bottom. In some species, other males have been seen swimming in a pair during spawning and releasing their sperm. Approximately 28-30 hours after fertilization, a pelagic larva hatches from the egg and hangs upside down just below the water’s surface. This is due to the presence of oil droplets. In their development there is so called tholichthys larval stage, unique among reef fish, in which the animal’s head is covered with ‘armor’ made of thin bone plates that extend beyond the head to form dorsal and abdominal spines. The shape and form of the plates and spikes varies from species to species. All tholischthys larvae are silver in color,  have a deep body flattened laterally. Bone plates are absorbed within a few weeks after the larvae sink to the bottom. The larvae settle during the night and quickly develop into juveniles. In many species, the coloration of juveniles is different from that of adults.

    Masking coloration

    Butterflyfishes do not take care for their offspring. Due to the small size of the body, they can easily fall prey to predators. Therefore, most species have a band covering the eye and a dark spot, the so-called false eye, located near the tail. These intend to confuse predators that aim for the head but actually attack the back of the fish’s body. Due to their attractive coloration, they are popular as aquarium fish. When selecting the appropriate species, however, it should be remembered that some of them feed on corals and anemones, which is why species that eat zooplankton are more popular.

    Butterflyfishes as indicator species

    Representatives of the Chetonidae family are considered indicator species that testify to the condition of coral reefs. This is due to the fact that they are bound to this habitat. Of the 5,000 species of fish that live on coral reefs, only 41 of them feed exclusively on corals. The majority, as much as 61%, belongs to the Chaetodontidae family, which is 25 species out of the previously mentioned 41. The dying of reefs contributes to the reduction of the number and diversity of butterflyfishes.

    Pennant coralfish Heniochus acuminatus

    Heniochus acuminatus
    Heniochus acuminatus

    Butterflyfishes are the most popular tropical fish among divers and aquarists. Among them is the Pennant coralfish belonging to the genus Heniochus, inhabiting the tropical waters of the Indo-Pacific, from East Africa, through South Japan to New Guinea. It inhabits coral reefs and sheltered coastal bays. Mature individuals are usually found in pairs, sometimes forming herds, while juveniles are solitary. The body length of the Pennant coralfish ranges from 15 to 20 cm. It can be distinguished from other representatives of Chetonidae by its elongated back and bony protuberance on the head. The length of the ridge on the back increases as the fish matures. Its oval, laterally flattened body is white with two broad black bands running vertically behind the eye and behind the dorsal process. Yellow dorsal and caudal fins are also characteristic. This fish has a long snout that allows it to reach its main food source in the crevices of coral reefs, i.e. small invertebrates. It also does not despise coral polyps. Juveniles sometimes clear other fish of parasites. Little is known about the reproduction of this species. It produces small, floating pelagic eggs. Hatching time is 18 to 30 hours. The previously described stage of tholichthys is present in their larval development. The larvae remain at this stage for several months and are then planktonic. H. acuminatus is a very beautiful and popular fish, quite easy to care for, which is why it is sold as an aquarium fish.

     

  • Soft corals

    Soft corals

    Phylum: Cnidaria

    Class: Anthozoa

    Order: Alcyonacea (soft corals)

    Alcyonacea are purely marine animals occurring only in the form of polyps. There are approximately 1,290 species of soft corals belonging to 6 suborders and 41 families. Representatives of this order are related to reef-forming (stony) corals, but lack the massive calcified skeleton of calcium carbonate. Instead, they have small limestone sclerites (fine spiky skeletal elements) in their bodies that provide some support and give their flesh a spiky, grainy texture that scares off predators. Several species, incl. blue coral (Heliopora) or pipe coral (Tubipora), have a solid skeleton, seemingly resembling hard corals. Moreover, their polyps always have 8 arms, unlike the stony coral polyps which have 6 or a multiple of 6.

    Appearance

    Soft corals are one of the most colorful and diverse groups of invertebrates found on coral reefs. They create colonies of various forms, incl. membranous, inlaid, massive, lobed, finger-shaped, woody, fan-shaped, bushy and whip-shaped. In the Caribbean, branching gorgonians and sea fans are the predominant forms of growth, while in the Pacific they are much more diverse, including fleshy corals as well as gorgonians. Although soft coral colonies do not contribute to reef growth, they provide shelter for many reef dwellers. Many animals, such as hydrophilic species, hydrozoans, bryozoans, crinoids, molluscs, crustaceans, and fish, find their shelter among corals, largely only on specific coral colonies. Many species of seahorses look similar to their hosts, thanks to which they perfectly camouflage themselves, eg. Hippocampus bargibanti inhabits only two species of the corals of genus Muricella and Hippocampus denise (fine seahorse) inhabits, i.a., colonies of corals of the genus Muricella, Anella and Echinogorgia.

    Longevity

    Soft corals include species with different biological characteristics and different ecological requirements. Many species are long-lived with a slow growth rate, while others are fast colonizers with a short life span. Some large colonies of the genus Sinularia (family Alcyoniidae) are probably hundreds of years old. The life expectancy and growth rate of most soft corals is largely unknown as colonies can shrink, due to both biological and physical factors, so there is a poor relationship between colony size and age.

    Environment

    Most soft corals, unlike stony corals, thrive in nutrient-rich waters with less intense light. Their food consists of small particles caught directly from the water column in the form of phytoplankton, fine particles of detritus, ciliates, flagellates and very small zooplankton. In addition, almost all of them use a symbiotic relationship with photosynthetic zooxanthella (alga) as their primary energy source. In return, the coral provides the algae with nutrients and shelter. This symbiosis depends on the availability of light for photosynthesis. There are taxa that do not bond with algae. Their only food is particles suspended in water, so they are highly dependent on water currents, therefore they occur in habitats with a large flow of water. They can be easily distinguished from those living in symbiosis with algae by their light yellow, orange, red, pink, purple or snow-white color.

    Reproduction and colonisation

    The dispersal strategies for soft corals vary between species, and include both asexual and sexual reproduction. Rapid colonization of small surfaces of the substrate is mainly related to asexual reproduction. It often involves the formation of stolons, the budding of miniature colonies which then fall off the parent colony and settle nearby, and fragmentation. Larger areas of the bare substrate are usually colonized by settling pelagic larvae formed by sexual reproduction. Then, mature individuals release their gametes into the water column, where fertilization takes place. The resulting pelagic larvae are scattered by currents over long distances. Once they reach the right size, they will settle down to days or weeks after conception. Fertilized eggs of some species remain attached to the mother colony, and the resulting larvae develop on the surface of the colony. After a few days it separates and settles to the bottom near the mother colony.

    Diffence strategies

    Many species protect themselves from predators, algae or contamination by neighboring organisms by releasing repellants, which are sometimes toxic. Many of these substances have been tested for their bioactivity, and some of them may become useful in the pharmaceutical industry. The main defense products are terpenoid in origin and despite their toxicity to fish, some specialized fish species are able to feed on corals. E.g. corals of the genus Sarcophyton sp. produce toxic sarcophytoxide, which released to aquatic environment causes reduction in the photosynthesis of the algae living in the symbiosis with coral Acropora formosa. Thus, it serves not only as a means of protection against being eaten by predators, but also provides an advantage in competing for living space with other corals. Sarcophytoxide, however, is not an obstacle for the gastropod Ovula ovum, which feeds on those corals and the toxin most probably is metabolised and detoxified in the intestines of the snail. Among the representatives of the gorgonias, such as the species Leptogorgia virgulata, there are substances such as lophotoxin. Their main task is to scare off the fish through stimulating vomits. In addition, they have antimicrobial properties, preventing coral overgrowth. Antarctic corals are protected either exclusively by limestone splinters or by chemicals. Eg., coral Ainigmaptilon antarcticus produces sesquiterpene that prevents starfish from feeding and inhibits development of the bacteria and diatoms. Separate strategy of the chemical defense can be observed in species Plexaura homomalla that produces large quantities of toxic prostaglandines and make the coral flesh untasty for, e.g., fish.

    Significance

    Soft corals are animals that produce many bioactive compounds with various effects, including antibacterial, antiviral, anticoagulant, antidepressant, antihypertensive, analgesic, anthelmintic, etc. Therefore, they are very commercially important. They are very easy to breed in captivity, much easier than hard corals that are susceptible to infection or damage. Soft corals grow quickly and are easy to divide into new individuals, therefore aquacultured corals are often more durable and cheaper than those imported from nature. Moreover, thanks to such farms it is possible to protect wild reefs. In the past it was believed that soft corals are not able to produce new fundaments for future coral reefs, however, recent discoveries suggest that the colonies of the genus Sinularia have an ability to cement their sclerites and fix them at the base, what makes them reef-building animals.

  • Baltic DigiTour

    Baltic DigiTour

    Seed Money Project: Baltic DigiTour

     Imagine being part of a dynamic online group of like-minded practitioners to mutually support each other keeping pace with ever new digital challenges and opportunities! How to set up and maintain such group for tourism attractions is what the project “Connectivist Massive Open Online Courses for Digitalization in Baltic Tourism Attractions” – or in short “Baltic DigiTour“ – is about to investigate.

    “Baltic DigiTour“ is a seed money project, co-financed by Interreg Baltic Sea Region within the European Regional Development Fund. Seed-money shall support the consortium of this one-year-project to conduct background investigations and thereby prepare for developing a fully-fledged main project.

    Implementation period

    01.10.2020 -30.09.2021

    Partners

    Knowledge on digitalization is constantly evolving, vastly spread across organizations and countries, and thus very complex to pool under one organizational entity’s governance. An online community approach to distributed knowledge agglomerating in a virtual space could provide an alternative to deal with this complexity. Building an online knowledge community is embraced by the concept of cMOOCs: connectivist Massive Open Online Courses. While MOOCs (Massive Open Online Courses) provide teacher-based knowledge publicly online and therefore scaling the outreach of teacher knowledge, cMOOCs emphasize the collaboration of learners and other knowledge sources. The connectivist approach sees all participants as both learners and teachers, with the mutual exchange building the dynamic content and value of learning.

    In the current seed money project “Baltic DigiTour“, four different analysis will help to further detail the requirements and opportunities for a future main project:

    • Investigation of existing cMOOC models and success criteria (cMOOC analysis).
    • Initial research on content experts e.g. in universities, bloggers, online groups, projects on digitalization in tourism (Content matter experts’ analysis)
    • Analysis of needs and requirements of potential participants of the knowledge community and those who can make use of the developed underlying cMOOC concept and transfer it to other areas both within tourism and beyond (Stakeholder analysis)
    • Investigation of suitable cMOOC IT platforms along with an evaluation of resources, limitations, functionalities (IT platform analysis)

    Based on the findings, gaps will be identified and how an international project could help fill these. A full project plan will be developed from that, including the set-up of a suitable consortium. In addition, funding programs will be analyzed for suitability for the potential main project.

    The project supports the EU Strategy for the Baltic Sea Region (EUSBSR) in the Policy Area of ‘Tourism’.

  • Baltic Sea bottom as desert – truth or myth?

    Baltic Sea bottom as desert – truth or myth?

    WEBINAR 12.08.2020, 15:00 CET

    By many of us, the Baltic Sea is treated as a lifeless underwater desert, while in fact, the bottom zone is rich in flora and fauna. We will focus on zoobenthos, which includes organisms that dwell on the seabed regardless of whether they bury in sediments, walk on the bottom or simply just lie/sit on it. We will meet members of a few groups living in the Baltic – oligochaetes, polychaetes, molluscs and crustaceans. It is true however, that, due to periodic or permanent oxygen deficits, lifeless areas occur on the Baltic seabed. Oxygen depletion is mainly caused by eutrophication. Another significant environmental problems involve remnants after World War II that pollute the sea water. Will the pollution deprive the Baltic Sea of life? You will receive the answer during a webinar with educators from the Gdynia Aquarium.

    The webinars are in English.

    More information about the event >>

    More information about the cycle of webinars “I live by the sea – summer school” >>

     

     

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