Pestes e visitantes indesejados

[João Branquinho]

Excelente artigo do João Cotter publicado na bioaquaria.com

 

Part 1 - http://www.bioaquaria.com/?p=7925

Part 2 - http://www.bioaquaria.com/?p=7965

 

 

Pests and unwanted visitors to the reef tank

By João Cotter | on March 22, 2014 | 0 Comment

Corals Marine Reef keeping

As our reef tanks evolve and keep more coral and other invertebrate species in improved conditions for success, we also create the appropriate conditions to certain unwanted predators and parasites. Thought to be immune to such scourges? Be aware and intervene at the slightest sign, before it's too late...

Featuring photo (above): Phidiana hiltoni © Marlin Harms

If you read issue bioaquaria’s first printed issue, namely the article «Biodiversity and its importance in 'closed' ecosystems», it is likely you remember the discussed concepts related to biodiversity in captivity, such as in the aquarium, as well as the controversial issue related to the fact that the aquarium can be considered an open or closed system in terms of biodiversity and energy exchange. The vastness of the oceans and all its intricate relation of trophic chains, commonly finds itself some sort of balance between the various populations of different species. The species that we know in our oceans are the result of these relationships, adjustments and adaptations that nature made over millions of years. Like the major geological accidents and natural catastrophes that Earth has faced throughout its life, also the human impact induces a forced adaptation of biodiversity by requiring that certain species give rise to other and, sometimes, some significant reductions in biodiversity occur.

© Silke Baron

Unlike certain freshwater biotopes in captivity, that present reduced biodiversity, usually marine tanks, more specifically the reef ones, show a significant species abundance, most of which the aquarist is completely unaware of their presence in its own tank.

A beautiful, smart crustacean, and probably with the greatest speed and accurate eye vision of the animal kingdom. A predator of respect. Featuring Gonodactylus smithii. © JennyHuang

As we said in the 2006/2007 article, there is a very significant input of energy and biodiversity by the reef aquarist. Most of this biodiversity originates in rock that is introduced and in some corals that shelter other living beings. Despite the fact that this multitude of living beings in the rock present a very positive aspect for maturation, filtration and overall health of the aquarium, it is impossible to fully prevent introducing unwanted living beings. The increasing diversity of species of cnidarians in our tanks and the improvement of the conditions in which we hold them, are also factors that facilitate the introduction and spread of pests, predators and other unwanted opportunistic beasts. Exclusively from the aquarist viewpoint, we call unwanted beings to those that inhibit or disrupt development and growth, somehow damage or eliminate creatures that the aquarist truly and deliberately intends to own and expose in its aquarium.

It is assumed in this article, a common sense perspective, ie, the aquarist mainly intends to keep certain species of coral and fish in its tank. When talking about other present living beings, it is generally intended to introduce some kind of benefit to the aquarium or, at least present no negative impact in it.

There are, of course, aquarists who purposely keep certain beings usually considered harmful, such as mantis shrimps, but these are special situations and specially prepared tanks for this intended purpose.

We begin by addressing, in this first chapter, the mantis shrimp, worms and nudibranchs.

The Mantis shrimp (stomatopods)

It is a common presence in live rock, mainly the ones imported from Indonesia. According to their size, they can be fatal for gastropods, crustaceans and other fish. The disappearance of these inhabitants, accompanied by sounds like "click" in your tank, is evidence of their presence. More information about these unwanted crustaceans and some tips so you may catch your mantis, may be found in the article Danger is lurking… The Mantis Shrimp.

Odontodactylus scyllarus © Charlene Mcbride

Worms

There are several types of worms that can cause havoc in reef aquariums. The flatworms, or Platyhelminthes, are dorsoventrally flattened invertebrate worms, like a leaf, with bilateral symmetry. They are a free and parasitic life form. They commonly reach the reef tank through live rock or corals. They feed on zooxanthellae, as well as coral tissue and are usually small and easily detected after visualizing the trail of dead coral tissue. A small population may not directly kill corals but can lead to secondary infections.

Red planaria

There are many species of harmful worms to corals. A purplish tone species and a whitish one are particularly harmful towards Acropora colonies. Red flatworms, although harmless to hard corals, reproduce very quickly, taking plague dimensions and covering much of the sediment, especially in the less illuminated areas of the tank. These ones attack soft corals and feed on zoanthids, whicht begin to close their polyps and quickly succumb. Some species of fish feed on these Platyhelminthes, as the Mandarin (Synchiropus splendidus), Pseudocheilinus hexataenia or Halichoeres chrysus, but not all individuals of these species cooperate to eliminate these pests. The best strategy is to physically remove the majority of these worms, sucking areas of the substrate where they are fixed. It's a tough and persistent daily task that may not be enough to keep the population at acceptable levels of Platyhelminthes. There are products on the market that eliminate them. However, note that these worms are toxic and, when dying, they release toxins into the water. If the population of Platyhelminthes in the aquarium is high, the application of these drugs triggers a very high mortality of worms and, consequently, very high levels of toxicity in the aquarium water, which will lead to death of the majority of living beings present.

Tubeworms © Jerry Kirkhart

There are also tubeworms – worms housed in tubes constructed by themselves – feeding on LPS corals. Although LPS corals may not show any visible signs of predation, they are gradually eaten, reducing its size. Physically remove any tubeworms you may find in the vicinity of LPS corals.

© Scubaben

Worm with stinging hairs © ScubaBear68

Stinging worms, or bristleworms, are annelids that grow quickly and can attack soft corals, particularly Euphyllia sp.. They habitually lodge under rocks or corals, or bury themselves in the sand and tend to attack corals that are not healthy. Larger individuals (15 to 40 cm) are usually harmful to corals and only come out of their hiding places at night to feed. They are difficult to catch because quickly retract to the hole where they’re hidden and, when caught, break easily, and the remaining parts will quickly grow back. Harlequin Tuskfish (Choerodon fasciatus) feeds on these large worms.

Chloeia flava worm. © divemecressi

Nudibranchs

Many nudibranchs show great beauty, but research first about the kind of appetite of these inverts! © Silke Baron

Nudibranchs get inside a tank through live rock or, in the case of the most unwanted and harmful to corals, through coral colonies crevices and holes. Most nudibranchs acquire their bright colours because they feed on coral nematocysts, and often imitate the colour of the coral host. Many nudibranchs have a very specialized diet, eating only certain species of cnidarians.

If you have Montipora corals in your tank, you must pay particular attention to Aeolidiidae nudibranchs family. In this family we find the famous Berghias that feed exclusively on Aiptasias sp. (other pest I'll discuss in the next chapter of this article) and other relatives (same family but different genera) that have a very similar appearance to Berghias but are true Montipora eaters. They lay their eggs in cavities and recesses of the coral and feed on the coral tissue. A large colony of Montipora sp. can be completely wiped out in less than one week. The eggs must be deposited in the coral so that newborn nudibranchs can feed as soon as they hatch. The literature indicates dipping affected coral colonies in freshwater as a solution to eradicate these nudibranchs during a maximum of 30 to 45 seconds. This will be enough time to kill the nudibranchs and not kill the coral colony. The pH and temperature of the freshwater should be similar to the tank. It is advisable to repeat the same procedure after 10 days to eliminate any nudibranchs that have hatched in the meantime.

An Aeolid nudibranch. © Ed Bierman

Although with some personal effort, and less stress to corals, I succeeded in suppressing these nudibranchs developing the following daily methodology:

• Place the coral in a container with water from your tank and shake the coral while in upside down position, so that nudibranchs fall in the bottom of the container.
• Discard the water from the container and refill it with new water from the tank. While maintaining the coral immersed in the container water, with the of a plastic pipette (commonly found in some test kits) vigorously squirt water over the coral, covering its entire surface, especially its cavities and recesses. You will see nudibranchs and small white dots (eggs) leaving the coral. Continue this process until nothing comes out from the coral colony and make it to all Montipora colonies in the tank.
• You must complete these tasks daily for a few days until there are no more individuals or eggs coming out of the corals.
• In the following days repeat the process with the pipette but with the coral inside the tank. Any nudibranch that escapes into the water column must be captured with the of the pipette.
• Eventually, some eggs may fall to the bottom of the tank. Do not worry, because after hatching, if they are distant from a coral host, they will not survive due to lack of food.
• Repeat this every day until you are sure that there are no traces of nudibranchs existence in Montipora corals.

This procedure worked well for me, completely eradicating these nudibranchs in a reef tank in about 10 days after having them first identified. Only one third of a Montipora capricornis was affected and a small area around the hole of a Montipora digitata, where most eggs are found located, as well as some adult nudibranchs. Note that soon as I started this intensive treatment, due to initial capture of most individuals, no longer the coral tissue significantly regresses.

Aeolidia papillosa © Jerry Kirkhart

Flabellina verrucosa © Minette Layne

Attacks from yellow nudibranchs to Sarcophyton sp. are also common. The procedures described above may also be effective in eradicating them.

Note that some universities or scientific groups may be interested in obtaining the beings that you may capture. Thus, avoid killing them (if you give them alive) and they will still be useful.

Hermissenda crassicornis © neoerik

In the next chapter I will discuss some more unwanted visitors to our reef tanks, such as Aiptasia sp. anemones, copepods known as Acropora red bugs (Tegastes acroporanus), certain kinds of algae, crabs, molluscs, starfish and protozoa. Obviously, I’ll try to offer a few tips to eliminate these pests.

Pests and unwanted visitors to the reef tank – part II

By João Cotter | on March 27, 2014 | 0 Comment

Corals Marine Reef keeping

In this part we conclude this article devoted to small beings that we want to keep away from our reef tanks, but accidentally or negligently, may arise and cause despair to the most amateur or more experienced aquarist.

Featuring photo (above): © Silke Baron

In the previous chapter we talked about mantis shrimps, worms (including flatworms and bristleworms) and nudibranchs. In this part we will devote our attention to starfish, Acropora red bugs, certain types of algae, crabs, molluscs, anemones and protozoa – a beautiful pest salad, on which you should be more careful from now on.

Echinoderms (starfish)

In recent years, a species of parasitic starfish was discovered. The small Asterina anomala can cause as much damage to a reef aquarium as an Acanthaster planci (crown-of-thorns starfish) causes to a natural reef. Asterina anomala grows doesn’t grow much and is easily missed in the tank, hiding within coral colonies and exposing only at night to feed on polyps. Its colouring varies between beige and gray and presents seven branches instead of five, with all arms being different in terms of size. The appetite of these little starfish is quite voracious. A single individual is able to consume any medium coral in a few days, particularly Euphyllia, Lobophyllia, Stylophora, Seriatopora,Acropora, Blastomussa, ie, most corals kept in aquaria, whether soft corals, LPS and SPS. The rapid dissemination of these beasts is due to its easy reproduction. Be aware and remove these starfish during the night (which is when they are active) with the of tweezers. It is a daily process until you can completely eliminate its population. It is known that Hymenocera elegans shrimp is a natural predator of this starfish and could to completely eradicate its population.

Asterina anomala starfish

This starfish arrives unnoticed through live rock and some corals.

Acropora red bugs (Tegastes acroporanus)

Tegastes acroporanus is a small copepod that has been giving lots of headaches to Acropora owners. This small 0.5 millimetre crustacean, similar to a mite, has a higher propensity for Acropora. It has a yellow coloration and a small red spot at one of its ends.

Tegastes acroporanus parasitizing Acropora granulosa © Marc (melevsreef)

Apparently, it parasites and feeds on mucus and by-products produced by Acropora. The first symptoms of their presence are the coral polyps retraction and its loss of colour. If this occurs, inspect the coral closely looking for small yellow/red dots. The development of this pest in a coral colony leads to inhibition of its growth and, subsequently, its death.

Several treatment methods have been tried. The singnathid Corythoichthys haematopterus is a natural predator of small crustaceans housed in corals, so it may be a significant .

Another option with good results is to dip the coral colony in a mixed iodine solution with aquarium water for about 15 minutes, using a container for this purpose. Lugol's solution is the ideal base for this process as other products commercially available in the hobby.

Another method involves treating a hospital (or quarantine) tank with Milbemycin oxime. This chemical is the active ingredient of some drugs used for deworming domestic animals, such as dogs and cats, and should be prescribed by a veterinarian. In some European countries you may find this chemical as veterinary medicines, like Interceptor,Milbemax or Program Plus, although, in the latter two, their composition also includes Praziquantel and Lufenuron and should, therefore, be excluded. This drug directly attacks crustaceans and is an invasive and risky treatment because it fails to distinguish between pests and other inhabitants, like shrimps, amphipods, copepods and crabs. Therefore, be careful to treat the infected colonies in a separate tank. In http://www.melevsreef.com/redbugs.htmlsee a detailed photographed description of a treatment following this method.

Algae

Some species of algae become real pests in a reef tank. We will not cover filamentous (or hair) algae in this article because it already was the subject of an article in bioaquaria’s #13 issue. A common pest often found in live rock is Valonia algae (also known as "bubble algae"). If ignored, it will multiply and eventually dominate much of the tank due to its rapid growth and reproduction. Try pulling the "bubbles" at its base without bursting, because bursting probably releases new cysts of algae to the water column. The acanthurid Zebrasoma desjardinii is usually quite effective in eliminating this algae species. The crab Mithrax may also be effective, but subsequently may bother corals.

Valonia sp.

Certain species of Cauperpa as C. racemosa and C. lentillifera may also quickly dominate the bedrock of the aquarium. Avoid the proliferation of these macroalgae, removing them physically at the lowest sighting. They tend to climb up corals and cause degradation of water quality when trying to reproduce sexually, especially when water conditions are not favourable to them, as in the event of iodine shortage.

Caulerpa lentillifera © djpmapleferryman

The occurrence of small brown or yellowish spots in rocks, sand and glass is a sign of diatoms. These ones are very difficult to remove physically. Try to reduce dissolved nutrients in the water, mainly silicates, because diatomaceous microalgae build their skeletons from silica. Partial water changes and the use of specific resins for silicates are solutions to the gradual elimination of diatoms. Some urchins feed avidly on diatoms. Note that diatoms appear naturally in the early assembly of a marine tank, quickly depleting the silicates and ultimately self-limiting their existence.

To avoid algae plagues, keep nutrients from the water to zero levels, particularly with regard to nitrates and phosphates and manually remove algae immediately as you spot it.

Zebrasoma desjardinii © Diogo Lopes

Aiptasia sp.

The popular anemone Aiptasia has been widely treated by dedicated aquarium literature as a fairly common pest. It reaches the tank in live rock and grows quickly, finding favourable feeding conditions. It reproduces itself by subdividing and can assume pest status in about a month if immediate measures for their removal are not taken. Their nematocysts sting everything they touch, including some corals and fishes.

Berghia verrucicornis and some Aiptasias in the back

There are some recipes of certain solutions to inject in the anemones, such as kalkwasser or lime water, lemon juice, vinegar or specific drugs. All these have been widely recommended and used with variable results but not 100% effective. Biological methods have proven more effective in the long term to completely eradicate these pests. Butterflyfishes like Chaetodon striatus and Chelmon rostratus consume these anemones, although not all individuals of these species may exhibit this appetite for Aiptasias. Berghia verrucicornis, a small nudibranch, feeds exclusively on Aiptasias and is highly effective in its removal. It will, however, take several months to completely eliminate the pest population.

Chaetodon striatus © Roban Kramer

Crabs

Certain crabs can cause quite enough damage to a reef tank. There are crabs that feed exclusively on Xenia corals and others, like most hairy crabs, are usually predators and carnivorous, feeding on everything, including fish, molluscs, other crustaceans and even some cnidarians. There is even a group of crabs with bright bluish eyes that feeds on SPS coral polyps. Use tweezers to pull these crabs from the corals in which they are housed. DO NOT be confused with the harmless small crabs of the genus Trapezius, who inhabit in SPS corals.

The blue eye crab is an SPS coral parasite.

You may adopt some methodologies to capture crabs similar to those illustrated in the article Danger is lurking… The Mantis Shrimp.

Note that crabs with the tips of the tweezers shell-shaped (like small spoons) are exclusively algivorous and, therefore, are harmless to the remaining animals in the tank and are even beneficial for the reduction of algae in substrate. Before eliminating a crab from your tank, be sure of its "intentions", ie , find out what species or group does he belong to.

Molluscs

Be aware that some nasty gastropods will come out of nowhere in your tank. © Damien du Toit

Certain gastropods such as whelks and snails are carnivorous, opportunistic creatures and have a specialized feeding on certain beings that you intend to keep in your aquarium. It is common to possess certain gastropods in the tank over which you do not suspect of what it feeds on. Indeed, these beings have an identical appearance to any ordinary herbivorous or detritivore gastropod (such as nassarius snails), but, unlike the benign animals, these are aggressive carnivorous, feeding on a wide variety of invertebrates, as zoanthids and Actinodiscus. Some gastropods have a venomous radula used to inject a lethal toxin into their prey. In other species, the radula is used as a drill for drilling the shell of other molluscs, including Tridacnas, and then feeding of its mantle. Fish species like Pseudocheilinus hexataenia and Pseudochromis springeri feed on some species that prey on Tridacnas.

Tridacna maxima © Alain Feulvarch

Some snail species may feed on corals © Roban Kramer

Some gastropods are specialist feeders, feeding exclusively on some coral species.

Due to the increased activity of these nocturnal beings, act when the lights are off, manually removing them from the tank. Use tweezers to catch them, due to venomous radula of certain species.

Pseudocheilinus hexataenia © Pedro Gama Conceição

Protozoa

We already know that there are protozoa that parasitize fish (vd. "White spots on freshwater and saltwater fish" inbioaquaria #16). You might not know that some of the unexpected deaths of certain corals, LPS and SPS in particular, are caused by some protozoa. Euphyllia sp. is particularly vulnerable to some protozoa and, if not removed immediately, the coral will become a brown pile of jam. Quick freshwater baths cleanse the coral of protozoa. The dead coral tissue should be removed due to the spread of secondary infections.

Euphyllia sp. © Diogo Lopes

Other protozoa feed on hard coral zooxanthellae, which make these end up starving to death. Infested colonies will present much faded colours. Again, freshwater baths of about 30 seconds can be very effective in eliminating these protozoa.

These protozoa rapidly destroy a coral as soon as they occupy it, so you need to act quickly.

Quarantining live rock and corals before putting them in the main tank is increasingly a recommended practice, as is increasingly the invasion in our tanks of beings who we didn’t even suspect would exist. Every day new discoveries are made. Be aware, search, read and isolate what you suspect. Ignorance is probably our worst enemy.