Phaeophyta Forest


October 1, 2017 by katerinazapfe, posted in Coast, Coast & Shores, Kelp, Kelp forest, Marine conservation

Stands of giant bladder kelp, Macrocystis pyrifera, tower over the sea beds below, swaying with the currents in impressive, underwater scenescape. It is often mistaken for a plant, but is actually a type of algae. Algae have fascinated scientists for centuries, and their specific classifications are still to this day quite controversial. Most textbooks agree the multicellular, photosynthetic nature of some algae falls under plants and unicellular algae fall under Protista. Regardless of the literature, we can be certain that algae are very diverse, photosynthetic organisms that have found ways to survive in both freshwater, saltwater, and even alongside fungi.

Marine algae are grouped into three main types: chlorophyta (green algae), rhodophyta (red algae) and phaeophyta (brown algae). One of the most impressive specimens belongs to the brown algae: giant kelp. Kelp can grow at an astounding rate of three feet per day in optimal conditions. It thrives in nutrient-rich, cold waters and keeps growing horizontally once it reaches the surface. The large, brown form we see is actually only half of the story; Kelp takes on two forms. The image of kelp we know belongs to the sporophyte stage, aptly named for ‘the stage that produces spores’. This is the towering, commonly seen form. The spores created by this form will grow into either male or female gametophytes, which are actually quite small and inconspicuous. The Gametes this small form releases join their two half-sets of DNA to grow yet another sporophyte and the cycle continues.

Young kelp lay down root-like projections over rocks on the seafloor, anchoring it against the current. Unlike true roots, this holdfast won’t help with nutrient uptake, but rather it grows throughout the kelp’s life into a tangle of strong branchings. The stipe, or stem-like structure connects the leaf blades. Each blade is made buoyant by a gas-filled chamber at its base called a bladder. These bladders multiply at the growth tip until the blade has two bulbs, upon which the blade splits lengthwise forming a new buoyant blade. In this way, these massive organisms grow to form giant forests that provide cover and hunting grounds for a whole host of marine life. Residents range from urchins and rockfish to seals and grey whales.

Many value the kelp forests for their economic opportunities, and it gives in a multitude of ways. The same brown, slippery mass that sometimes washes up on beaches supports urchin fisheries, rockfish fisheries, and provides shelter and habitat for a whole ecosystem. Its beauty attracts recreational divers and the kelp itself can be harvested and used in products like shampoos, frozen foods, and products that call for the bonding agent algin. Kelp forests are in danger today from the overharvesting of fish. If too many fish are taken, their prey, such as kelp-eating urchins, experience a marked increase. These large fluctuations in population can cause the kelp forest ecosystem to become imbalanced. This coupled with the increase of water pollutants from runoff pose a threat to the forest’s wellbeing, even if many are already within marine protected areas. Luckily, scientists are studying this ecosystem in hopes of its long-term preservation.

Learn more about how you can help:

  •    Learn how scientists are helping save the kelp

  •    Sign the petition to vote down commercial harvesting in Bantry Bay

#kelpforest, #coast, #marineconservation

Richard Hyman