Miyakojima Mangrove

1. what are mangroves?

What is a mangrove?Although often misunderstood, mangrove is a general term for plants that grow near the mouths of rivers where seawater and freshwater mix, and is not the name of a specific plant.

Generally, mangroves grow on land that is flooded with water.

Miyako Island has no rivers flowing into the sea; instead, there are many underground water vein outlets near the coast.

The mangrove forests of Miyakojima have continued to develop in a way that is unique to the island, growing in clusters around them.

In mangrove forests, trees grow so densely together that their roots and branches intertwine with each other, forming a characteristic surface structure.

Because the intertwined roots and branches serve as shelter for a variety of animals, mangrove forests are home to many creatures such as crabs and birds, creating a rich ecosystem.

 

Mangrove plants can spread their roots into salt water where trees normally cannot grow naturally.

So how does one enable it to grow wild in salt water?

There are two features of mangroves that solve this problem.

(First) Root Mechanism

Mangrove roots have a mechanism to control the inflow of salt.

This allows only fresh water to be assembled and flushed from salt water.

(Second) Leaf Mechanism

Mangroves can pass through salt-blocking mechanisms in their roots and salt accumulated by direct sea breezes can accumulate in their leaves.

By defoliating leaves that have accumulated salt, the mangroves themselves are prevented from accumulating salt.

In this way, mangroves have adapted themselves to their environment so that they can survive in harsh conditions.

In addition, mangrove seeds germinate where they drift, with some of their fruit falling down as they grow, being carried away by water currents or pierced by mud.

 

Shimajiri mangrove forest

The largest mangrove forest on Miyako Island is the Shimajiri Mangrove Forest.

It is located in the northern part of Miyako Island, in front of Ikema Island.

From the parking lot, there is a boardwalk that leads directly to the mangrove forest. Although it is a boardwalk, it is a wooden walkway, so it is recommended that visitors wear comfortable shoes and clothing, not pin-heels or other shoes that are hard to walk in.

Also, since there is no shade near the Shimajiri mangrove forest, it is a good idea to bring a hat, sunglasses, or other sun block and sunscreen.

The trip from Miyako Airport takes about 20 minutes by car.

However, it takes about 10-15 minutes each way to walk the boardwalk from the parking lot to the mangrove forest.

Therefore, it takes up to 30 minutes for a round trip, so it is advisable to plan your schedule well in advance for sightseeing and other activities.

The major attraction of the Shimajiri mangrove forest is the variety of mangrove species it contains.

All mangroves on Miyako Island, including "Yaeyama Hirugi," "Ohirugi," "Mehirugi," "Hirugi damashi," and "Hirugimodoki," can be seen in the Shimajiri mangrove forest.

Sea activities are also popular among tourists.

Canoe and kayak tours are available throughout the year to enjoy observing the mangroves and aquatic life, and you can also observe the mangroves from a closer distance.

Tour start times are in the morning or afternoon and reservations are required.

 

Kawamitsu Upkar

Another mangrove community on Miyako Island is the Kawamitsu Mangrove.

Although much smaller than Shimajiri, it offers a creative sight of mangroves spreading out in a spring-fed waterway that empties into Yonaha Bay.

Upukā" generally refers to a "big river," and even in Kawamitsu there are many springs, and the village has developed supported by the river and its waters.

Kawamitsu Mangrove is located not far from Miyakojima Airport on National Route 390.

Mangroves such as "Yaeyama Hirugi", "Ohirugi", and "Mehirugi" have been identified in Kawamitsu Upukar.

It is also a spot where you can see butterflies such as the giant sesame butterfly, wild birds, and various other creatures living in harmony with the mangroves.

Along the boardwalk surrounding Kawaman Upkar, there is a viewing deck and pavilion, as well as benches and tables, so that visitors can take a stroll while viewing the mangroves and take a break if they are tired.

The boardwalk turns into a stone path in the middle of the road, but be careful, as it sinks into the water at high tide.

Also, please note that it is slippery after rain.

 

2. what are the types of mangroves?

In the mangrove forestIf you know the time of low tide on the day you visit, it is recommended to visit around that time.

This is because it is possible to observe the mangrove footprints that emerge as the tide recedes and the interesting organisms of the mudflats.

On the other hand, around high tide, you can see completely different scenery, such as mangroves immersed in water and shimmering.

Also, before visiting a mangrove forest, it is helpful to learn what kind of mangroves can be seen so that you can enjoy the experience more when you actually visit.

Here are some of the types of mangrove forests.

 

〇ヤエヤマヒルギ

一本の幹の根元からたこ足のように根が出ており、葉の先端はとがっています。

樹高4m～8mで、マングローブ林の海側に育ちます。

 

〇オヒルギ

樹高5m～10mと高めで、姿が男性的というところから名前がつきました。

地上に根を張り巡らせ、開花時には小さく赤い花が咲きます。

吸い上げた海水の塩分を葉っぱに集めることができ、塩分を吸い上げて黄色くなった葉を落葉させます。

マングローブの中では比較的陸側に育ち、地面の下の根から膝根という根を地上に現すことが特徴です。

絶滅危惧II類VUに指定されているマングローブです。

 

〇メヒルギ

樹高2m～5mで、樹形が清楚であるということから名前がつきました。

マングローブの中では陸側に育ち、特徴的な板根を持ちます。

他のマングローブに比べると、やや寒さに強いため、鹿児島県など沖縄よりも経度が高い地域でも育つことができます。

メヒルギもオヒルギと同じく、準絶滅危惧種に指定されているマングローブです。

 

〇ヒルギモドキ

ヒルギ科ではありませんが近しい種類です。

ヒルギに似ているのでヒルギモドキと名付けられました。

樹高2m～4mで、明るい色の光沢のある葉が特徴で、砂地にも定着することができます。

群生地では後背地を好んで育つマングローブです。

根は水平に張り、絶滅危惧ⅠA類に指定されています。

 

〇ヒルギダマシ

樹高50cm～2mで、ヒルギモドキと同様にヒルギ科ではありませんが近縁です。

割り箸を立てたような筍根が出るのが特徴的で、マングローブの中では海側に育ちます。

絶滅危惧ⅠB類に指定されています。

 

＜マングローブの中に住む生き物たち＞

〇ミナミトビハゼ

地元では「とんとんみー」と呼ばれるハゼ科の魚です。

目が大きく体長10cmほどの魚で、泥の上をぴょんぴょんはねて移動する姿がかわいらしいです。

 

〇ベニシオマネキ

体が赤色のカニです。

人の気配がすると一斉に泥の穴の中に隠れてしまいますが、しばらく静かにしていると、ベニシオマネキが少しずつ顔を出し、写真のように地面のあっちこっちに赤い点々が見えてきます。

 

〇ミナミヒメシオマネキ

こちらもカニの一種で、2020年3月に新種であることがわかったものです。

シオマネキのオスは、片手のハサミが大きくなります。

ハサミが大きいほどメスに人気があるそうです。

 

〇コメツキガニ

ミナミヒメシオマネキ同様、こちらも新種であることがわかったカニです。

カニといえば横向きに移動する姿が想像されますが、コメツキガニは横だけじゃなく、縦にも歩けるという特徴を持っています。

このカニも人が近づくと一斉に泥の中に隠れますが、しばらく静かにみていると、少しずつ姿を現します。

 

〇ガザミ

宮古島では食用とされています。

地域によっては「ワタリガニ」と呼ばれ、北海道から宮古島まで広く生息しているカニです。

 

3. 周辺のご案内

〇パーントゥ

島尻は、「パーントゥ」という、体中に泥を塗って神々に扮した人々が集落の中を歩き回り、集落の人々に泥を塗りつけていくお祭りで有名です。

集落の島尻購買店では、いろいろなグッズが売っています。

泥を塗られた人は災いが落ち、幸運が舞い込むと言われるお祭りです。

旧暦の9月上旬ごろに行われる日本でも珍しいお祭りですので、ぜひ訪れてみてはいかがでしょうか。

 

4. まとめ

マングローブ林には数々の植物と生物を見ることができます。

雄大な自然を感じられるスポットとして非常におすすめです。

宮古島に旅行する際には、島尻マングローブ林や川満マングローブへ訪れてみてはいかがでしょうか。