The hammerhead shark

The hammerhead shark

The common hammerhead shark (Sphyrna lewini) is one of the most important predator species that inhabits the waters of the tropical and subtropical regions.

This species of shark breeds every two years as soon as it reaches sexual maturity at eight years of age. It can be up to four meters long, and feeds mainly on fish, crabs, invertebrates and rays.

At an ecological level, this predatory species are very important for the reef ecosystem since it helps to control the abundance of fish and rays, maintaining a healthy marine environment. Actually, large predators tend to play an important role in the balance of marine ecosystems.

The shape of the head is the most spectacular feature of the hammerhead shark. Behavioral studies have shown that the head has multiple sensory pores that help them detect pressure changes in the water. This way it can detect the prey under the sand such as stingrays.

The hammerhead shark spends their early years near the coast, in wetlands and river mouths. At the age of four/ five, it migrates to the open sea and that is where they reproduce. Later, the female returns to the coast to give birth where they have a symbiotic relationship with the reef fish, such as angelfish or butterfly fish. They clean their wounds and parasites.

Hammerhead shark 

Currently, sharks from all around the world are facing a very serious threat as they are being massively hunted for their fins. The fin of the hammerhead shark is highly valued in the Asian market because it is considered to be of good quality and very fibrous, especially for traditional fin soups.

The hammerhead shark is one of the most threatened shark species, with global populations reduced by almost 90%. They’re listed in the second appendix of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites), this means that despite the fact that it can be fished, it cannot be exported.

We have to be aware of how sensitive marine ecosystems and their inhabitants are and what we can do to preserve the ocean’s biodiversity.
Small things like buying locally, not buying endangered species or endangered species from other countries, volunteering and raising awareness about endangered species have a huge positive impact on wildlife conservation.

Fin has been cut

El pez loro

El pez loro

 Una especie vital para los corales

El pez loro es uno de los animales herbívoros más importantes en el equilibro de los arrecifes del caribe que pasan hasta el 90 % de su tiempo comiendo y puede cambiar su sexo varias veces a lo largo de su vida. Actualmente hay registradas  80 especies distintas de este ejemplar.

Este pez se encuentra en los arrecifes tropicales de todo el mundo. Para alimentarse, tritura y traga pedazos de coral, extrae las algas adheridas y defeca el resto en forma de arena gracias a sus potentes mandíbulas en forma de pico de loro y de sus muelas compactas para pulverizar el coral. Algunas especies llegan a vivir hasta veinte años y existen de distintos colores.

Hay zonas en las que el pez loro muele tanta cantidad de coral muerto, que su producción de arena supera a la de cualquier otro proceso de la naturaleza. Algunos investigadores calculan que el pez loro común produce unos cien kilos de arena al año.

Los peces loro también son esenciales para la supervivencia de los corales, ya que actúan como “limpiadores naturales” de los parásitos que crecen en ellos. Sin la ayuda del pez loro el coral se vería seriamente amenazado. La pérdida de peces loro altera el delicado equilibrio de los ecosistemas de coral y permite que las algas, de las que se alimentan, no sofoquen los arrecifes. Desde la década de los 70 ha habido una pérdida importante de corales en el caribe consecuencia directa de la pérdida de peces loro y erizos de mar (dos herbívoros principales de la zona) y no solamente debido al cambio climático, otro factor que amenaza seriamente este ecosistema.

Por estas razones debemos proteger al pez loro, así lograremos también proteger y salvar a los arrecifes coralinos.

Pez Loro, un aliado para los corales.

Tiburón Martillo

El tiburón martillo

 

El tiburón martillo común (Sphyrna lewini) es una de las especies de depredadores más importantes que habita las aguas de las regiones tropical y subtropical.

Esta especie de tiburón se procrea cada dos años apenas alcanza su madurez reproductiva a los ocho años de edad. Puede llegar a medir hasta cuatro metros de largo, y se alimenta principalmente de peces, cangrejos, invertebrados y rayas.

A nivel ecológico esta especie depredadora es muy importante para el ecosistema de arrecife ya que que controla la abundancia de peces y rayas, manteniendo un ambiente marino sano. Los depredadores grandes tienden a tener ese papel importante en el balance de los ecosistemas marinos.

La forma de la cabeza es la característica más espectacular de esta especie. Estudios del comportamiento han demostrado que la cabeza tiene una serie de poros sensoriales que los ayuda a detectar los cambios de presión en el agua. De esta forma puede detectar presas bajo la arena como las rayas.

El tiburón martillo se cría cerca de la costa, en humedales y desembocaduras de ríos grandes; a partir de los cuatro o cinco años migra hacia el mar abierto y es ahí donde se reproduce. Posteriormente, la hembra regresa a la costa a parir y allí recibe una limpieza de heridas y parásitos por parte de peces de arrecife, como el pez ángel o el pez mariposa.

https://www.ucr.ac.cr/noticias/2018/04/04/tiburon-martillo.html

Actualmente los tiburones del mundo enfrentan una amenaza muy grave ya que están siendo cazados de forma desproporcionada y sin control por su interés en la comercialización de las aletas. Esto también está sucediendo con el tiburón martillo.

La aleta del tiburón martillo es muy cotizada en el mercado asiático por considerar que es de buena calidad y muy fibrosa, en especial para las tradicionales sopas de aletas.

Como resultado, el tiburón martillo se encuentra actualmente en grave peligro de extinción. Es una de las especies de tiburones más amenazada, con poblaciones a nivel global reducidas casi en un 90 %.

El tiburón martillo es una especie en peligro de extinción que se encuentra en el segundo apéndice de la Convención sobre el Comercio Internacional de Especies Amenazadas de Fauna y Flora Silvestres (Cites, por sus siglas en inglés), por lo tanto, a pesar de que se puede pescar no se puede exportar.

Esto nos lleva a reflexionar sobre qué tan sensibles son los ecosistemas marinos y sus habitantes y como nosotros podemos actuar para preservar la fauna marina, siendo conscientes de nuestras acciones del día a día como por ejemplo comprar de forma local, no comprar especies en peligro o amenazadas que vengan de otros países, hacer voluntariados y crear conciencia sobre la situación de estas especies son solo algunas de las formas más sencillas de empezar a cambiar hacia una visión positiva.

Información de UCR y National Geographic

www.lareserva.com/aletas_tiburon_espana

How are the coral reefs formed?

How are the coral reefs formed?

To understand how coral reefs are formed, we must first learn what a coral is.

Corals are living organisms that can be found in tropical warm waters (more than 20ºC), with high salt concentration. Together they form a massive calcareous structure which are known as reefs. They are the communities with the biggest and greatest biodiversity in the world.

These organisms live in a symbiotic relationship with an algae called Zooxantela, an unicellular algae capable of photosynthesis that is able to reproduce and live inside the coral tentacles. The corals ability of building their own calcium skeleton is because of this algae, it provides the necessary carbon. The corals are modular animals called polyps.

Soft Coral

Grupo de pólipos corales individuales que conforman una colonia

de corales pétreos. Crédito de la foto: Charles LoBue/EPA.

What’s a reef? 

The term reef refers to the biological use that is given to a three-dimensional structure that rises from the seabed. It has not been built exclusively by coral, but also by sponges, algae and marine worms.

What’s a coral reef?

The coral reef ecosystem consists of a group of corals that segregate rigid calcareous skeletons and live in colonies of the most diverse shapes and sizes that interact, along with other species, as a functional unit.

The coral reefs are one of the most productive and complex ecosystems in the world. In the entire reef structure, the living part of the reefs is a layer of one millimeter of tissue that is found on top of it, everything else is a skeleton that serves as habitat and food for other species.

The reef is the most diverse marine system. The coral reefs have so much diversity that are often compared to a tropical forest.

Coral Reef

The formation of coral reefs

The coral reefs of the tropical seas are a typical example, forming the greatest living community that populates the seas; built by tiny and primitive animals belonging to the group of coelenterates or Cnidaria known by the name of corals.
There are approximately 2,500 different species of coral that have the ability to extract calcium carbonate from seawater and make limestone skeletons from it for their own protection. As polyps multiply in one place and add layer upon layer of their calcareous skeletons, large reefs are formed inhabited by millions of animals and plant and animal organisms.

The coral reef being the most prosperous vital community known, it is home to the greatest wealth and variety of plant and animal creatures, ways of life and relationships of conduct.

By way of differentiation, it can be said that the coral is the one who builds the reef. Coral is the engineering species, it creates an environment and allows other species to live in it.

NOAA Coral Reef Conservation Program

What’s happening with the Corals?

What’s happening to the Corals?

Out of approximately 248,00 square kilometers of coral reef ecosystems around the world, a vast amount grows in the Americas. Specifically, Costa Rica has 970 kilometres of coral reef and together with Panama, Colombia and Ecuador they make up 1% of the world’s coral reef and 10% of America.

In the Caribbean coast, you can find coral reefs mostly in the south (from Limón to Manzanillo) and they grow better and in extensive areas than in the pacific coast. Cahuita has the most expressive area of coral reef (with a total of 5 km) that unfortunately in 2006 had its percentage of live coral reduced from 40% to 15%. The corals of Costa Rica are under a serious threat.

Drone photography by Juandi Gutierrez

What is killing our corals?

In general, the most common causes that have negative effects on the health and coral reefs survival are:

  • Sedimentation.
  • The contamination ( Fertilizers, hydrocarbons, pesticides, among others..)
  • The excessive and unauthorized fishing.
  • The fast coastal development without proper planning.
  • Excessive tourism.
  • Big storms, hurricanes, climate changes and other natural events.
  • The excessively low tides that expose the upper part of the corals to air.
  • Extreme saturation of carbon dioxide in the water that makes it more acidic.
  • Fishing with with dynamite and cyanide.
  •  Diseases of the corals itself.
  •  The introduction of exotic species in the environment. Like the lionfish.

Lion Fish

What can we do to help with coral conservation?

  • Save water: The less water you use, the less contaminated water ends up in the sea.
  • Help reduce water contamination: Emissions from cars and industry contribute to the rise of oceans temperatures, which is the main cause of the fast coral.
  • Use organic fertilizers: Chemical products travel through the rivers and subterranean water and end up contaminating the oceans, causing irreversible damage.
  •  Recycle and use less plastic.
  • Support organizations that have an active role on coral reef conservation.
  • Plant a tree: Trees help prevent contaminated water and other elements from reaching the ocean. Also, you will be helping the planet on the climate change issue.
  • Practice water sports with responsibility: Don’t touch the corals. Always try to reach an area with sand to walk on far from the reefs.
  • Be active on beach cleaning: Every year there’s dozens of organizations that get together to collect trash from the beaches around here. Join and participate.
  • Pressure the government to take action and create more protected areas to prevent ocean’s contamination. Let them know the importance of these incredible ecosystems and the need to protect them. Fight for our natural resources and support our natural reserves.
  • Have an active voice on coral conservation: Share your causes with as many people as you can. People have to realize the importance coral reefs have on our ecosystems, there’s a lot of organisms depending on coral to live and a lot of biodiversity will be lost if we don’t do anything about it.