Reef Ramblings

The 1^st of June saw the first annual conference of the new coral reef aquarium initiative, the Coral Aquarist Research Network (CARN) take place at the Royal Geographical Society in London.

CARN was formed in October 2009 as a network to foster the exchange of knowledge, expertise, and experience between coral reef researchers and those working in the various fields of aquarium related industries such as suppliers, public aquariums, coral growers, and hobbyists. It is hoped that the creation of this network will provide opportunities for the various coral industries to collaborate with the world class coral and reef biology research community in the UK.

This first conference included presentations that were both research and industry orientated, highlighting the status of knowledge, technology and importantly gaps in our understanding of coral physiology, ecology, transport, growth and sustainable harvesting.

A special issue of the JMBA, one of the UK’s leading marine biology centric journals, will be devoted to the proceedings of the conference.

The day started of with an introduction to the conference by Philippa Mansell from the University of Essex, project manager of CARN.

The conference was split into four sessions of talks, each session based around a theme. Although some of the talks were of a scientific nature the bulk of them were easily accessible to the keen hobbyist. Concluding each session there was a period set aside for questions and answers, enabling conference participants to further exchange information or ask questions clarifying aspects of the presentations.

For the purpose of this article, I’m just going to briefly list the presentations with a few comments on their relevance to the hobbyist.

The session on Coral Eco-physiology was fairly technical, looking at: Mechanisms of thermal induced coral bleaching and the implications for reef community structure ( Dr David Smith, University of Essex), effects of trace metals on reef anthozoan pigmentation (Edward Smith, National Oceanography Centre, Southampton) , and the influence of the light climate on colouration of reef corals (Dr Jörg Wiedenmann, National Oceanography Centre, Southampton). The research being carried out here will have a benefit to hobbyists enabling them to keep bright coloured corals and better maintain their colouration.

The second session, Coral Ecology and Biodiversity, included a fascinating talk on Mushroom corals (Fungiidae) and their associated fauna in the Coral Triangle (Dr Bert Hoeksema, Netherlands Centre for Biodiversity), looking at the various animals that live on or in these popular aquarium corals. The Importance of Symbiodinium diversity: implications for the aquarium trade (Patrick Brading, University of Essex), was about the various species of symbiotic dinoflagellates, the zooxanthellae that live within coral tissue. Environmental influences on coral growth – from Indonesia to the Caribbean (Professor James Crabbe, University of Bedfordshire), gave an insight into how the environment affects the way that corals grow in nature and how this might affect their growth in aquaria.

The session looking at the coral industry and conservation examined issues of conservation, sustainability, and management of resources with presentations on the trade in reef corals (Dr Elizabeth Wood, Marine Conservation Society), the UK trade in ornamental polychaetes or Fan-worms (Joanna Murray, University of Portsmouth), and whether the coral industries can play a role in the future conservation of coral reefs (Philippa Mansell, University of Essex). An important issue, greatly affecting the future of the hobby.

The conference finished of on the subject of aquarium based research and workshops and featured a talk on Coralzoo (Dr Ronald Osinga, Wageningen University), an initiative looking at four years of public aquarium research on stony corals, my own presentation discussing Coral Nutrition in the Captive Environment (Tim Hayes, Midland Reefs), and a report on the 5^th SECORE workshop, a program investigating sexual reproduction in stony corals (Jamie Craggs, Aquarium Curator, Horniman Museum).

CARN is an initiative that welcomes you, the hobbyist, to join in and share your experiences of keeping corals in your reef aquarium. You can do this by going to the CARN website, http://carnuk.org/getinvolved.aspx, there you can share information about the corals and other reef organisms that you’ve kept, with top reef scientists who are very interested in looking at how these fascinating animals fare in the captive environment in comparison to how they live in the wild. For advanced hobbyists it could also offer the opportunity to ask questions of reef scientists based on observations of your reef aquarium.

Together we can take the reef aquarium hobby forward through the exchange of information, perhaps in the process improving long term survivability of reef organisms and the sustainability of the hobby.

Tim Hayes

Midland Reefs

©2010

The New England Aquarium in Boston, Massachusetts, joined up with Rogers Williams University in Bristol, Rhode Island, in a project to raise the world’s first captive-bred Queen Triggerfish.

The New England Aquarium’s Bahamian coral reef exhibit features a pair of Queen Triggerfish, Balistes vertula, which have been seen to spawn since their early days in the aquarium. Although these fish regularly lay tens of thousands of eggs every 18 to 20 days, the resulting larvae need live food of a small size, making them difficult to feed and keep alive.

Most marine fish larvae are very small and need live food of a correspondingly smaller size. Whereas some species, such as clownfishes, can be successfully raised using rotifers, organisms that grow and reproduce at a fast rate and in high densities, these are too large for many other species or don’t have the correct nutritional profile needed.

In the wild larval marine fish eat copepods, micro-crustaceans found virtually everywhere in the oceans, but raising copepods in large enough quantities is currently difficult. This is one of the reasons why far fewer species of marine aquarium fish are captive bred than are wild caught.

Eggs were collected from the aquarium and taken to the university’s marine laboratory where, at the first attempt, there was a successful hatching.

Although thousands of larvae hatched, work was concentrated on a relatively small number, which were initially fed with a local species of copepod grown by the lab.

Although the majority of the larvae died, four were successfully raised to the point where they could eat dry food and now, at more than four months old, remain alive, three at the university and one at the aquarium, the first triggerfishes to have been successfully bred in captivity.

The success of this project was largely due to Dr. Rhyne’s research into copepods, the critical live food for marine fish larvae.

Dr Andy Rhyne, assistant professor of biology at Roger Williams and a research scientist at New England, was hired in August 2009 in a collaboration between the aquarium and the university to study larval fish production at the aquarium and to start a program in aquarium science and aquaculture at the university.

Today many species of fish are threatened by a combination of overfishing, climate change, and environmental degradation, indeed the Queen Triggerfish is listed on the IUCN red list as being vulnerable. The species is important both as a food fish and for public aquarium displays. It’s a large species; reaching up to 60 cms total length and its bright colours make them a favourite of public aquariums although too large for the majority of home aquaria.

This is an important step in the cultivation of marine species, as researchers such as Andy Rhyne develop new feeding strategies, it increase the chances of being able to raise further species of marine aquarium and food fish in captivity, rather than continuing to take them from the increasingly vulnerable and deteriorating oceans.

To find out more about this wonderful achievement go to MOFIB to see Andy Rhyne’s diary recording the day-by-day progress of the project.

Congratulations, Andy!

Tim Hayes

Midland Reefs

©2010

The United Nations has declared 2010 to be the International Year of Biodiversity. It is a celebration of life on earth and of the value of biodiversity to our lives. The world is invited to take action in 2010 to safeguard the variety of life on earth: biodiversity

As part of the International Year of Biodiversity (IYOB) the IUCN has published a report presenting 10 new climate change flagship species to demonstrate that it’s not just the Polar Bear that’s in trouble.

These 10 species are as follows:

Staghorn corals

Ringed Seal

Leatherback Turtle

Emperor Penguins

Quiver Trees

Clownfish

Arctic Foxes

Salmon

Koalas

Beluga Whales

One thing that is immediately obvious from the list is that 7 of the species are marine animals. The second thing to strike me about this list is that 2 common aquarium animals are included, most worrying of all is the inclusion of the poster animal of the marine aquarium hobby, the clownfish

In this first of two articles I’m going to look at clownfish, the second article will be concerned with Staghorn corals.

Clownfish and Climate Change

Clownfish, or Anemonefish, belong to the Family Pomacentridae, with their vivid orange and white colouration are one of the most familiar species of tropical marine fishes. This familiarity was boosted by the film ‘Finding Nemo’, which featured the Common Clownfish, Amphiprion ocellaris, a mainstay of the marine aquarium hobby.

Clownfish are found in tropical and subtropical areas of the Pacific and Indian Oceans where they are restricted to shallow waters owing to their mutualistic relationship with a small number of specific anemone species. A host anemone can support a colony of several clownfish consisting of one female, one functional male, and a number of subordinate fishes, all non-functional males.

When the female dies the male turns into a female whilst the largest subordinate fish becomes male. Clownfish lay their eggs close by their host anemone, guarding them until they hatch. On hatching the larvae disperse into the water column where they remain for around 8 to 12 days before settling out as juveniles and seeking a host anemone of their own. As larvae develop, chemical signals allow them to detect suitable host anemone.

Research has shown that the larvae that survive to settle out as juveniles tend to return to the reef where they originated so the majority of the survivors do not disperse very far from their parents’ anemone.

There are 28 species of clownfish described to science; all behave in a similar manner, exhibiting reliance on their obligate association with host anemones for survival.

Captive breeding.

Clownfish have been bred in captivity since the early eighties so we have a lot of information about how different environmental conditions such as temperature and pH affect this species. Although it’s interesting to note that the recent studies from the reef, revealing that reduction in ocean pH levels have an affect on clownfish’s ability to detect the chemical signals necessary for locating an anemone host, answer the question of why captive bred clowns are often slow to adopt an anemone in a reef aquarium.

Why are Clownfish vulnerable to the effects of climate change?

Habitat loss: Coral reefs are in decline owing to increased levels of CO2 in the atmosphere. The current level stands at 387 ppm CO2, higher than 350 ppm that many leading scientists say is the safe upper limit for carbon dioxide in our atmosphere, and the level we need to get back to as early as possible to avoid runaway climate change. If CO2 levels reach 450 ppm, predicted to occur by 2030-2040 at the current rates of increase, reefs will be in terminal decline worldwide from mass bleaching, ocean acidification, and other environmental impacts. Clownfish are dependent on anemones for their survival, which most frequently occur on coral reefs.

A couple of examples: the global coral bleaching event of 1998, led to the complete disappearance of several sea-anemone species used by clownfish in the corals reefs around Sesoko Island, Japan, causing local population declines; and take a look at: Reef Ramblings June/July 2008 to see an earlier article about reduction in clownfish numbers on the Great Barrier Reef.

Disruption of navigation: Decrease in ocean pH levels have been shown to affect a clownfish’s ability to detect the chemical signals that allow them to locate a host anemone. This is known to be a particular problem for juveniles as, if they’re unable to locate a host, they’re at greater risk of predation. Juveniles unable to locate a new anemone face the chance of returning to their parental anemone, increasing the likelihood of inbreeding.

Larval development: As ocean temperatures increase we’d expect to see faster development of larval and juvenile clownfishes. This may bring a reduction in dispersal distance with the result of settlement closer to the parental anemone increasing local competition for recruitment to neighboring host anemones. Again increasing the possibility of inbreeding.

Reproductive behavior: Clownfish, along with many other fish species, only reproduce within a narrow temperature range. This presents the possibility that as temperatures increase that there may be a reduction in breeding activity. A secondary problem that we’re familiar with from captive breeding is that high temperatures can have a deleterious affect on egg development.

It’s also worth noting that in the IUCN report, under the heading of “Other threats”, that the marine aquarium industry is singled out for mention, although it does go on to add that the greatest threat is down to human activities, presumably the usual

Can clownfish adapt to climate change?

Currently this is unknown, most species can usually adapt to changes in environmental conditions as long as these change occur slowly over time. As ocean temperatures continue to increase, clownfish and their associated host anemones may be able to shift their ranges southwards to cooler water. However, neither clownfishes, nor their anemones, are particularly mobile so it’s likely that successful relocation to new, more suitable habitats will be limited.

The concern about more rapid larval development, with its resultant limitation on dispersal, raises the question of inbreeding, the consequences of which are unknown.

A further possibility, but one that seems to me unlikely, is whether clownfishes could adapt to seasonal breeding pattern taking advantage of the cooler seasons.

Interestingly, the IUCN report states the one species of clownfish has recently been shown to use soft corals as an alternative habitat, something previously only seen in captivity. This is referenced to Arvedlund, M., and Takemura, A. (2005) Long-term observation in situ of the anemonefish Amphiprion clarkii (Bennett) in association
with a soft coral. Coral Reefs 24, 698-698.

It’s not known if other species of clownfish could adopt other host species, nor whether such associations would have the same value as the present association with anemones.

What can we do?

Whilst climate change does not mean extinction, some species will be able to adapt whilst others will perish. The question is which species will survive and which will perish? Worsening climate change effects are inevitable, even if all CO2 emissions ceased today, because of the lag-effects of the greenhouse gasses already emitted.

It’s up to all of us, along with our governments, to commit to targets to reduce emissions at the earliest opportunity if, we want to slow the pace of climate change and give clownfishes and other species a chance to survive.

If you are a reefkeeper, try to raise awareness of the destructive affects of climate change to the marine environment by using the familiar clownfish as an example of what may be lost.

You can download the IUCN report here: Species and Climate Change

Tim Hayes

Midland Reefs

©2010