CEI 2017 Research Presentation

Topic 1

Threats and Conservation of Horseshoe Crabs in Hong Kong

Doris Cai, Chun Lam, Vincent Yik, Jeanie Yung

Horseshoe crabs have an evolutionary history of 400 million years, appearing 200 million years before the dinosaurs. Horseshoe crabs are not crabs; they are in fact more closely related to spiders and scorpions. According to the World Wildlife Fund for Nature Hong Kong, the blood of this species contains high amounts of copper and thus turns blue when exposed in air. Their blood has great economic and medical value because it can be manufactured as a reagent to detect bacterial contamination.

Only four species of horseshoe crabs remain in the world today. They are Carcinoscorpius rotundicauda (Mangrove Horseshoe Crab), Limulus polyphemus (Atlantic Horseshoe Crab), Tachypleus gigas and Tachypleus tridentatus (Chinese Horseshoe Crab). Horseshoe crabs are found in Southeast Asia, along the American Atlantic coast and in the Gulf of Mexico. Intertidal zones are the habitat of juvenile horseshoe crabs. Mature horseshoe crabs migrate to the sea, and return to the shore in breeding season.

Horseshoe crabs play an important role in the intertidal food web. The eggs of this species are a source of food for some birds; at the same time, horseshoe crabs consume dead bodies of worms, clams and fish.

Third, juvenile and adult horseshoe crabs are common prey for sharks and sea turtles such as loggerhead.

In the fields of science and medicine, horseshoe crabs are of high value too. The large lateral compound eyes are used to study cellular mechanisms of retinal function in humans. The blood of the horseshoe crabs contains a chemical named Limulus Amebocyte Lysate (LAL), which can be used to produce a reagent for detecting bacterial contamination.

Among the four species of horseshoe crab species found globally, there are two found in Hong Kong. However, researches (Li; Shin; Shin, Cheung & Laurie) point out that extensive reclamation and coastal development destroy the spawning habitats of horseshoe crabs, resulting in a dramatic reduction in their population in the territory.

While in some other parts of the world, water pollution also poses a threat to this marine species. Sewage, oil, plastic and waste from human activity pollute the coastal areas and sea water. According to Bottom and Itow (2009), horseshoe crab spawn has been heavily impacted by pollutants.

The horseshoe crab is becoming an endangered species in Hong Kong and many other parts of the world. According to research from the Ocean Park Conservation Foundation, Hong Kong, the survival rate of horseshoe crabs in the wild is 0.01%.

In our recent project, since November 2016, in collaboration with the Ocean Park Conservation Foundation Hong Kong and the Department of Biology and Chemistry of the City University of Hong Kong, attempts have been made to raise 15 juvenile specimen of Tachypleus tridentatus in the laboratory of our school. The plan is to release these juvenile horseshoe crabs in a selected mudflat habitat in Hong Kong in June 2017 when they become stronger and less vulnerable to danger in the wild. It is hoped that this project can assist in raising the survival rate of this endangered species in Hong Kong.

The 15 horseshoe crabs were raised in carefully controlled environment with optimal salinity, temperature and dissolved oxygen. Their growth was monitored by meaning their weight and carapace width weekly. At the same time, a booth was set up to educate schoolmates about the importance of conserving this marine species.

Simple actions can contribute to the survival rate of horseshoe crabs in the wild. These include keeping our coastal areas free from pollution, refusing to purchase and consume horseshoe crabs, and showing concern about to coastal development proposals. We hope that, through this project, more people can be inspired to take action for the conservation of horseshoe crabs.

Topic 2

Threats and Conservation of Fireflies in Hong Kong

Leo Chan, Quentin Chan, Desmond Hui, Edwin Ho

In a natural ecosystem, fireflies eat snails and worms. For example, earthworms and freshwater snails. Fireflies are thus important ecologically as they help control the population of their prey through consumption. On the other hand, fireflies are also food for spiders, frogs, mantises, freshwater shrimp and crabs.

Fireflies are facing a few threats in Hong Kong: diminishing habitats and light pollution are the most common. Many firefly habitats in Hong Kong, mainly in woodland and freshwater areas, have been developed into urban areas. Light pollution also weakens the light of fireflies, which means interruption of their communication with their own kind.

In our recent project, there has been an attempt to identify the main threats fireflies face in Hong Kong. In the past few months, we have been working closely with the Hong Kong Firefly Conservation Foundation (http://hongkongfirefly.weebly.com). We participated in a workshop, fieldtrip, and a two-day camp organized by this organization. Also, under the guidance of this organization, a piece of woodland near our campus has been identified as a potential site for fireflies rehabilitation.

In that piece of woodland, a few fireflies have been observed. Subsequent field surveys on firefly larvaes and quality of river water have been carried out. It was found that the quality of the river water in the woodland is satisfactory. In the future, we will continue our work on this piece of woodland, turning it into a suitable habitat for fireflies. Collaborating with the Hong Kong Firefly Conservation Foundation, breeding of fireflies in the school laboratory will be attempted. It is hoped that the population of wild fireflies will be raised through this effort.

Polluting the environment means not only a worse living environment but also threatening various species in nature. Through this project, it is hoped that the awareness of our schoolmates towards the environment could be raised. A booth was set up to spread the message of environmental conservation for fireflies. It is planned that when fireflies are being bred in school in the future, live demonstrations can be carried out for first-hand exposure of our schoolmates to this species.

Small actions make significant impact. Our damage to nature is far greater than we assume. In our everyday life, there are several measures we can take to protect fireflies too. Switching off or dimming lights is helpful to allow fireflies to communicate with their lights effectively. Limiting the illumination area of street-lamps is also contribute to the conservation of fireflies especially in rural areas.