Ice-ice is a disease condition of

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

. Ice-ice is caused when changes in

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

ocean temperature The ocean temperature varies by depth, geographical location and season. Both the temperature and salinity of ocean water differs. Warm surface water is generally saltier than the cooler deep or polar waters; in polar regions, the upper layers of ...

and light intensity cause stress to seaweeds, making them produce a "moist organic substance" that attracts bacteria in the water and induces the characteristic "whitening" and hardening of the seaweed's tissues.DOST.gov.ph:
/ref> Bacteria involved include those in the ''

Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Being highly salt tolerant and unable to survive ...

Aeromonas ''Aeromonas'' is a genus of Gram-negative, facultative anaerobic, rod-shaped bacteria that morphologically resemble members of the family Enterobacteriaceae. Most of the 14 described species have been associated with human diseases. The most imp ...

'' and ''

Cytophaga ''Cytophaga'' is a genus of Gram-negative, gliding, rod-shaped bacteria. This bacterium is commonly found in soil, rapidly digests crystalline cellulose ''C. hutchinsonii'' is able to use its gliding motility to move quickly over surfaces. Al ...

Flavobacteria The class Flavobacteriia is composed of a single order of environmental bacteria. According to Bernardet ''et al''., Flavobacteriia are Gram-negative aerobic rods, 2–5 μm long, 0.3–0.5 μm wide, with rounded or tapered ends ...

'' complexes. The bacteria

lyse Lyse may refer to: * Lyse Abbey, a former Cistercian abbey in Norway * Lyse, an alternative name of Lysebotn, Norway * Lyse Energi, a Norwegian power company * Łyse, Masovian Voivodeship, a village in east-central Poland * Łyse, Podlaskie Voivode ...

epidermal cells The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water relea ...

and

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

s, turning the seaweed tissue white. The disease is known from seaweeds including ''

Kappaphycus alvarezii Description ''Kappaphycus alvarezii'', the elkhorn sea moss, is a species of red algae. The elkhorn sea moss varies in size, weight, and age. It is a dark greenish-brown hue and can sometimes be deep purple. The moss is cylindrical in shape th ...

'' and ''

Eucheuma denticulatum ''Eucheuma denticulatum'' is a species of red algae and one of the primary sources of iota carrageenan. It exists naturally in the Philippines, tropical Asia, and the western Pacific, but for the commercial extraction of carrageenan it is usuall ...

'', economically important sources of

carrageenan Carrageenans or carrageenins ( ; ) are a family of natural linear sulfated polysaccharides that are extracted from red edible seaweeds. Carrageenans are widely used in the food industry, for their gelling, thickening, and stabilizing properties. T ...

. In countries where seaweed is harvested as a crop, ice-ice can wreak havoc on yields. Zamboanga, Philippines, had an outbreak of ice-ice in 2004, and

Bali Bali () is a province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller neighbouring islands, notably Nusa Penida, Nusa Lembongan, and Nu ...

, Indonesia, experienced an outbreak in 2009.JakartaPost: Rising sea temperatures bad news for seaweed farmers
/ref> A rise in surface sea temperatures of 2–3 degrees Celsius can trigger ice-ice outbreaks. __TOC__

Pathogens

Analysis has been performed to determine the pathogens affecting the '' Gracilaria verrucosa'' and ''

'' seaweeds. Morphologic and phenotypic characteristics (16s RNA analysis) showed that the isolates from diseased ''Gracilaria'' belong to various genera: ''

Chromobacterium ''Chromobacterium'' is a genus of Gram-negative rod-shaped bacteria. Currently, eleven species within the genus are known, two of those are ''Chromobacterium violaceum ''Chromobacterium violaceum'' is a Gram-negative, facultative anaerobic, ...

Flavobacterium ''Flavobacterium'' is a genus of Gram-negative, nonmotile and motile, rod-shaped bacteria that consists of 130 recognized species. Flavobacteria are found in soil and fresh water in a variety of environments. Several species are known to cause ...

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...

'', and ''

Achromobacter ''Achromobacter'' is a genus of bacteria, included in the family Alcaligenaceae in the order Burkholderiales. The cells are Gram-negative straight rods and are motile by using one to 20 peritrichous flagella. They are strictly aerobic and are fo ...

''. They belong for the most part to the group of

Gammaproteobacteria Gammaproteobacteria is a class of bacteria in the phylum Pseudomonadota (synonym Proteobacteria). It contains about 250 genera, which makes it the most genera-rich taxon of the Prokaryotes. Several medically, ecologically, and scientifically imp ...

, already well known from disease-related study on seaweeds. For the seaweeds '' K. alvarezii'' a leading candidate bacterium has been identified: ''

Stenotrophomonas maltophilia ''Stenotrophomonas maltophilia'' is an aerobic, nonfermentative, Gram-negative bacterium. It is an uncommon bacterium and human infection is difficult to treat. Initially classified as ''Bacterium bookeri'', then renamed ''Pseudomonas maltophil ...

''. In most cases it seems these microorganisms are opportunistic pathogens. Some treatments have been investigated to cure these ice-ice infections, the

green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

Caulerpa racemosa ''Caulerpa racemosa'' is a species of edible green alga, a seaweed in the family Caulerpaceae. It is commonly known as sea grapes (along with the related ''Caulerpa lentillifera'') and is found in many areas of shallow sea around the world. There ...

'' seems to inhibit the action of the most part of these pathogens.

Effects

The disease seems to affect the formation of micropropagule of the algae. The protoplasm content is higher in a healthy micropropagule than in the infected ones. Protoplasm indicates occurrence of severe chronic infections of the micropropagules (algae disease are characterized by reduced number of cell

protoplasm Protoplasm (; ) is the living part of a cell that is surrounded by a plasma membrane. It is a mixture of small molecules such as ions, monosaccharides, amino acid, and macromolecules such as proteins, polysaccharides, lipids, etc. In some defini ...

Quere G, Meistertzheim A-L, Steneck RS, Maggy M. Nugues MM. 2015. Histopathology of crustose coralline algae affected by white band and white patch diseases. PeerJ 3:e1034. https://peerj.com/articles/1034/).

References

{{reflist Bacterial plant pathogens and diseases