• Skip to main content
AlgaeBarn

AlgaeBarn

Marine Aquariums Made Easy!

  • Sign In
  • Cart
    • Shop See All
      • Ultimate Packs See All
      • Ultimate Refugium Starter
      • Clam Keeper Kits
      • Ultimate Ecopack
      • Mandarin Feeder Kit
      • Hair Algae Killer Kit
      • See All Ultimate Packs
      • Live Foods See All
      • Copepods
        • Ecopods
        • 5280 Pods
        • Galaxy Pods
        • Poseidon's Feast
        • Tisbe Pods
        • Tig Pods
      • Food Combos
        • Ecopods & Phyto
        • Galaxy Pods & Phyto
        • Poseidon's & Phyto
        • Tig Pods & Phyto
        • Tisbe Pods & Phyto
      • Phytoplankton
        • Oceanmagik
      • Brine Shrimp
        • Simple Brine
        • Nano Brine Shrimp
      • Most Popular Products See All
        • Galaxy Pods 5 Species Copepod Blend

          Galaxy Pods

          $66 – $139
          Shop Now
        • Ecopods 4 Pack Special

          $99
          Shop Now
        • Galaxy Pods & Phyto Combo

          $80
          Shop Now
        • 5280 Pods

          $45
          Shop Now
      • Macroalgae See All
      • Clean Macro Series
        • Clean Chaeto
        • Clean Sea Lettuce
        • Clean Green Ogo
        • Clean Mocha Ogo
        • Clean Mocha Spike Sphere
        • Pom Pom
        • Red Ogo
        • Red Spike Sphere
        • Red Spaghetti
        • Red Mangrove
      • Premium Rare Macro
        • Leafy Ogo
        • Blue Hypnea
        • Dragon's Tongue
        • Thick Ogo
      • Most Popular Products See All
        • Clean Chaeto

          $40 – $125
          Notify Me When in Stock
        • Clean Sea Lettuce

          $30 – $95
          Notify Me When in Stock
        • Red Ogo

          $30 – $80
          Notify Me When in Stock
        • Red Mangrove

          $13
          Shop Now
      • Captive Bred Fish See All
      • Gobies
        • Green Mandarin
        • Court Jester Goby
        • Watchman Goby
        • White Spotted Goby
      • AngelFish
        • Biota Coral Beauty
        • Maculosus Angel
        • Majestic Angel
        • Swallowtail Angel
      • Tangs
        • Yellow Tang
        • Blue Tang
      • More Species
        • Grammas
        • FileFish
        • Blennies
        • Damsel
        • ClownFish
        • RabbitFish
      • Most Popular Products See All
        • Blue Mandarin

          BIOTA Green Mandarin

          $99
          Notify Me When in Stock
        • ORA Neon Goby

          $35
          Shop Now
        • Captive Bred Yellow Tangs by BIOTA

          BIOTA Yellow Tang

          $239
          Notify Me When in Stock
        • ORA Premium Picasso

          $145 – $300
          Shop Now
      • Captive Bred Invertebrates See All
      • Clams
        • Ora Derasa Clam
        • Squamosa Clam
        • Ora Gigas Clam
        • Ora Maxima Clam
        • Ora Hippopus Clam
      • Shrimp
        • Ora Peppermint Shrimp
        • Harlequin Shrimp
      • Snails
        • Cerith Snails
        • Trochus Snail
        • Nassarius Snails
      • Urchins
        • Ora Tuxedo Urchin
        • Ora Pincushion Urchin
      • Most Popular Products See All
        • Animated gif of peppermint shrimp

          Peppermint Shrimp

          $49 – $119
          Shop Now
        • 10 Cerith Snails

          Cerith Snail

          $25 – $39
          Shop Now
        • pincushion urchin lytechinus variegatus reef safe and captive bred by ora for sale at algaebarn

          Pincushion Urchin

          $29 – $55
          Shop Now
        • Gold Maxima Clam Bed

          ORA Maxima Clam

          $80 – $150
          Shop Now
      • Corals See All
      • LPS Corals
        • Biota Pearl Bubble
        • ORA Pearl Bubble
        • ORA Marshall Island Goniopora
        • ORA Marshall Island Hammer
      • SPS Corals
        • ORA Pearlberry Acropora
        • ORA Micronesian Imperial Acropora
        • ORA Turquoise Acropora
        • ORA Micronesian Yellow Porites
      • Soft Corals
        • BIOTA White Polyp Toadstool
        • ORA Long Polyp Leather Coral
        • ORA Silver Xenia
        • ORA Pulsing Xenia
      • Frag Packs
      • Most Popular Products See All
        • Biota Pearl Bubble Coral

          $65
          Shop Now
        • ORA Pearlberry Acropora

          $290
          Notify Me When in Stock
        • BIOTA White Polyp Toadstool

          $65
          Notify Me When in Stock
      • Additives & Bacteria See All
      • Live Cultures & Bacteria
        • Turbostart 900 Saltwater
        • Aquarium Cycle Kit
        • Coralline Algae
        • PNS Yellosno
        • PNS Probio™
      • Additives & Chemicals
        • Nitrocycle
        • Clarifier
        • Fritz A.C.C.R
        • Fritz RPM Salt
      • Most Popular Products See All
        • Mandarin Feeder Kit by Algaebarn

          Mandarin Feeder Kit

          $66
          Shop Now
        • MarinePure 10 Cubes

          2″ Cubes

          $5 – $99
          Shop Now
        • Coralline Algae in a Bottle, In Pink or Purple!

          Coralline Algae

          $22 – $44
          Shop Now
        • Ultimate Refugium Starter Pack

          $120 – $450
          Shop Now
      • Aquarium Supplies See All
      • Fuge Lighting
        • AI Fuge 16HD Light
        • Kessil A360X Fuge Light
        • Kessil H160
        • Kessil H80
        • Chaetomax
      • Biomedia
        • Marinepure Gems
        • Marinepure Rocks
        • Marinepure Plate
        • Marinepure Cubes
        • Marinepure Spheres
      • Foods
        • Dragon Roe
        • Simple Brine
        • Can'O Cyclops
        • Benereef™
        • Fresco Cyclops
      • Rock & Sand
        • Dry Rock
        • Clam Rocks
      • Most Popular Products See All
        • Mandarin Feeder Kit by Algaebarn

          Mandarin Feeder Kit

          $66
          Shop Now
        • MarinePure 10 Cubes

          2″ Cubes

          $5 – $99
          Shop Now
        • Coralline Algae in a Bottle, In Pink or Purple!

          Coralline Algae

          $22 – $44
          Shop Now
        • Ultimate Refugium Starter Pack

          $120 – $450
          Shop Now
      • CADE Aquariums See All
      • Reef Series
        • CADE REEF 500 S2
        • CADE REEF 600 S2
        • CADE REEF 900 S2
        • CADE REEF 1200 S2
        • CADE REEF 1500 S2
        • CADE REEF 1800 S2
        • CADE REEF 2100 S2
      • Frag Series
        • CADE Frag 600 S2/F
        • CADE Frag 900 S2/F
        • CADE Frag 1200 S2/F
        • CADE Frag 1500 S2/F
      • Peninsula Series
        • CADE Peninsula 1200 S2/P
        • CADE Peninsula 1500 S2/P
        • CADE Peninsula 1800 S2/P
      • Most Popular Products See All
        • CADE REEF 2100 S2

          $7,225
          Shop Now
        • CADE Peninsula 1500 S2/P

          $5,525
          Shop Now
        • CADE REEF 1200 S2

          $4,125
          Shop Now
        • CADE Frag 900 S2/F

          $3,275
          Shop Now
    • Contests Win Free Aquarium Supplies!
      No Purchase Necessary*
    • Top Deals Huge Savings!
    • AlgaeBarn Heroes Discount for Military,
      First Responders and more!
  • Blog
  • About
  • Contact
  • Shipping
You are here: Home / Macroalgae / Ulva spp. Seaweeds: The Refugium Powerhouses

Ulva spp. Seaweeds: The Refugium Powerhouses

by Kenneth Wingerter

Virtually all marine aquaria have fish residing in them. And fish must be fed. Which is fine, because most hobbyists enjoy feeding their animals and do so quite generously. The result, however, is a whole lot of fish waste. These waste products are mineralized (that is, broken down) through biological processes into simple compounds such as nitrate and phosphate. In recirculating systems, these substances can rapidly accumulate. They are often referred to as nutrients because they are required in significant quantities for plant (e.g. algae) growth and reproduction. Hence, heavy blooms of nuisance algae can occur where nutrient levels are high. In a marine aquarium, this might mean tinted water and/or films that cover the rocks, sand and tank panels. No matter which way these plagues present themselves, they are a huge source of frustration for aquarists everywhere. In fact, much of the time and money spent on the typical  saltwater tank is aimed primarily at controlling (if not defeating) unwanted algal invaders.

To this end, some aquarists carry out messy and time-consuming water changes on a massive scale. Others employ expensive chemical media in expensive chemical media reactors. Increasingly, many others are using algae to fight algae. Typically, this involves cultivating a sizable standing crop of a macroalgae such as sea lettuce in a separate enclosure, usually referred to as a refugium. In theory, the macroalgae assimilate nutrients that they draw from the aquarium system water as they grow. These nutrients are merely locked up in the plant biomass, and are only exported from the system when portions of the crop is harvested and discarded. In some cases, they may be recycled if the refugium plants are periodically used to feed herbivores in the main tank.

[macroalgae]

Really, there are a handful of reasons why one might add a refugium to their aquariuulva2m system. The goal might be to create a “refuge” for copepods or just to keep a nice collection of attractive ornamental algae species to display. Some have joked that a refugium is simply an excuse to set up another tank (while explaining to the significant other that it is actually a special filter component). But if the primary goal of setting up a refugium is to reduce loads of dissolved nutrients in the aquarium water, the best choice is a hardy, fast-growing macroalgal species that not only tolerates, but indeed loves, polluted environments. For this job, sea lettuce is a prime candidate.

The common name sea lettuce generally refers to certain chlorophytes (green seaweeds) of the genus Ulva. The type species for the genus, U. lactuca, is found in shallow ocean waters nearly worldwide (the Americas, Northern Europe, Indian Ocean, China, New Zealand and beyond). Ulva seems to prefer nutrient-rich waters in shallow, brightly lit, partly enclosed shores such as in bays, estuaries or salt marshes. It can sometimes be found in great densities, forming a low-growing meadow over stony sea bottoms. It is particularly abundant where there are elevated concentrations of dissolved nutrients. Even when nutrient levels rise far above any natural level (as seen in some bays in Britain, where coastal waters have been heavily polluted by fertilizer run-off), this hungry seaweed thrives. In fact, the only thing that checks this weed’s growth in many areas is sea urchin grazing; lush meadows of sea lettuce form where sea urchins have been removed.

Ulva spp. really do resemble little, crinkly lettuce leaves. Its fronds take the form of broad blades that are often lightly shredded and have small holes. Like other seaweeds, it lacks true roots and attaches to hard surfaces by means of a disc-shaped (no stipe) holdfast. Simple and mostly flattened, the holdfast looks much like the plant’s fronds. In quieter tide pools, detached sections can grow to form fragile sheets several feet or more in length. Its fronds are bright green due to a high content of chlorophyll a. It is this, and their production of starch, that leads some botanists to propose that these are some of the closest seaweed relatives to land plants.

Highly palatable and nutritious, sea lettuce is important in the diet of many species (including some humans); even deer have been observed grazing on the stuff. It also is important as a biogenic habitat on which a diversity of other tiny organisms including bacteria, copepods and even other algae may dwell. There are even some interesting (but still poorly understood) relationships between certain marine fungi and Ulva. In this case, the fungi Guignardia sp. and sea lettuce form a “composite,” with the fungus being most evident as a wart-like growth around the plant’s thallus. It also appears that Ulva requires particular mysterious “growth substances” (derived from the secretions of benthic bacteria) to properly develop.

ulvaMembers of the genus Ulva have a life history that involves both haploid sporophyte and diploid gametophyte stages. While these plants can undergo a rather complex pattern of sexual reproduction, they are also capable of proliferating asexually by means of blade fragments that reattach on new rock surfaces or by expansion of the holdfast. Growth can be fast where the right conditions (namely nutrient-rich waters, intense, full-spectrum illumination and moderate water movement) are provided. Their ease of cultivation and aggressive uptake of pollutants has made them extremely popular in the aquarium hobby. While there is some element of seasonality in their productivity in the wild, they appear to be fully able to grow without pause in a stable captive environment. It grows well (and also looks rather good) when kept with certain other structurally complementary macroalgae such as Chaetomorpha spp. And, it of course makes for an extremely high-quality live feed for herbivorous fishes (many tangs, angelfishes, rabbitfishes, etc.).

While it is not quite as attractive as algae such as Gracilaria, Ulva is the first choice for many aquarists who are serious about using a refugium for nutrient control. And, unlike other fast-growing nutrient sponges like Chaetomorpha, it can be offered as a nutritious treat for the tank’s algae-eating inhabitants. Nevertheless, when grown in mixed beds with Chaetomorpha, it creates a perfect environment for the long-term culture of beneficial microcrustaceans. It’s no wonder that so many aquarium hobbyists regard sea lettuce as a super seaweed.

[macroalgae]

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Related Posts

Bulletproof Refugiums: Biodiversity

Welcome back to our discussion on building bulletproof refugiums! In the last few weeks, we have received a lot of questions here at AlgaeBarn about

Read More about Bulletproof Refugiums: Biodiversity

How Macroalgae Benefits Coral

Many hobbyists are constantly looking for ways to increase the health and vitality of their corals. There are many obvious ways to achieve better

Read More about How Macroalgae Benefits Coral

Bulletproof Refugiums: Water Flow

Welcome back to our series on building bulletproof refugiums! At AlgaeBarn, we have gotten so many great questions on refugium design and maintenance in

Read More about Bulletproof Refugiums: Water Flow

Didn't find what you were looking for?

Browse the AlgaeLab by Category

  • Advanced Education
  • Beginners Education
  • CADE Aquariums
  • Captive Bred Fish
  • Clean Up Crew
  • Company News
  • Copepods
  • Corals
  • Freshwater
  • Freshwater Aquariums
  • Intermediate Education
  • Invertebrates
  • Live foods
  • Macroalgae
  • Our Oceans
  • Phytoplankton
  • Product Info
  • Refugium Education
  • Rock and Substrate
  • Saltwater Aquariums
  • Wholesale

Company

  • About Us
  • The AlgaeLab Blog
  • Our Team
  • Careers
  • FAQ

Get in Touch

  • Contact Us
  • AOA Claim Form
  • Press Inquiries
  • Call Us: 772-444-7637

Policies

  • Legendary AOA Guarantee
  • Terms & Conditions
  • Privacy Policy

Other

  • Store Locator
  • Wholesale & B2B inquired
  • Business Location

Subscribe to our Newsletter

Join our mission to build a more sustainable aquarium hobby, one tank at a time!

Copyright 2023, AlgaeBarn LLC - Live Copepods and Phytoplankton

0

Your Cart is Empty

adroll_adv_id = "RWFLKG57L5GR7KGYSOEUOK"; adroll_pix_id = "CH2QRUFHXZELLLCMHAB5GI"; adroll_version = "2.0"; adroll_current_page = "other"; adroll_currency = "USD"; adroll_language = "en_US";