Composite materials promoting the catchment and attachment of seaweed holdfasts
Some aspects of the disclosure relate to composite materials and cultivation systems with particular utility for use in aquaculture, for example cultivating various species of seaweed. The systems comprise at least one highly tortuous and often micro-fibrous material and at least one material having low tortuosity. These systems may be configured in a variety of shapes and associated with a number of different structures. Some of these composite materials and cultivation systems may be used in both direct and indirect seeding of macroalgae plants such as seaweed.
1. A seaweed cultivation substrate for anchoring a holdfast of a seaweed plant in an aquatic environment, the substrate comprising:
a first cord extending over a first length and defining an exterior first cord surface configured to face the aquatic environment, the first cord comprising a plurality of first polymer fibers disposed proximate to each other along the first length and defining a first cross-sectional thickness of the first cord, each of the plurality of first polymer fibers further defining a first spacing between adjacent first polymer fibers, the plurality of first polymer fibers and the first spacing together defining a first natural path length extending from the exterior first cord surface and navigating around adjacent first polymer fibers to a first midpoint of the first cross-sectional thickness, the plurality of first polymer fibers and the first spacing together further defining a first tortuosity ratio of the first cord defined by the first natural path length compared to a first straight-line length measured from the exterior first cord surface to the first midpoint;
a second cord engaging the exterior first cord surface, the second cord extending over a second length and defining an exterior second cord surface configured to face the aquatic environment, the second cord comprising a plurality of second polymer fibers disposed proximate to each other along the second length and defining a second cross-sectional thickness of the second cord, each of the plurality of second polymer fibers further defining a second spacing between adjacent second polymer fibers, the plurality of second fibers and the second spacing together defining a second natural path length extending from the exterior second cord surface and navigating around adjacent second polymer fibers to a second midpoint of the second cross-sectional thickness, the plurality of second polymer fibers and the second spacing together further defining a second tortuosity ratio of the second cord defined by the second natural path length compared to a second straight-line length measured from the exterior second cord surface to the second midpoint;
wherein the second tortuosity ratio is at least 5 times greater than the first tortuosity ratio.
2. The seaweed cultivation substrate according to claim 1 , wherein the second tortuosity ratio is at least 50 times greater than the first tortuosity ratio.
3. The seaweed cultivation substrate according to claim 1 , wherein the said second cord comprises a micro-fibrous material comprising a network of linked fibers with an inter-fibril distance of about 1 μm to about 200 μm.
4. The seaweed cultivation substrate according to claim 1 , wherein the first cord comprises a bundle of nonlinked fibers.
5. The seaweed cultivation substrate according to claim 1 , wherein the first and the second cords have hydrophilicities that differ from one another.
6. The seaweed cultivation substrate according to claim 1 , the second cord has a density equal to or less than 1.0 g cm −3 and the first cord has a density greater than or equal to 1.0 g cm −3 .
7. The seaweed cultivation substrate according to claim 1 , wherein the said second cord comprises a micro-fibrous material comprising a network of linked fibers with an average inter-fibril distance (μm) and with an average density (g cm −3 ), and wherein the second cord has a ratio of the average inter-fibril distance (μm) to the average density (g cm −3 ) from about 1 to about 2000.
8. The seaweed cultivation substrate according to claim 1 , wherein the second cord includes at least one expanded fluoropolymer, expanded thermoplastic polymer or expanded polymer formed by chemical vapor deposition.
9. The seaweed cultivation substrate according to claim 1 , wherein the first cord is at least one material selected from the group of materials consisting of:
spun/filament polyester, spun/filament nylon, spun HEMP, and natural fibers.
10. The seaweed cultivation substrate according to claim 1 , wherein the cultivation substrate is in at least one of the forms selected from the group consisting of:
a braid, a knit, a yarn, a covered yarn, a nonwoven, a weave, a fabric, a particulate dispersion, a bead, a stitch-bonded fabric, and a laminate.
11. The seaweed cultivation substrate according to claim 1 , wherein the second cord forms a core having an external surface.
12. The seaweed cultivation substrate according to claim 11 , wherein the first cord is attached to at least a portion of the external surface of the core.
13. The seaweed cultivation substrate according to claim 12 , wherein the first cord is attached to the external surface of the core as bands spaced at any distance from one another selected from the range of about 0.9 mm to about 10 mm from one another.
14. The seaweed cultivation substrate according to claim 12 , wherein the bands are spaced more than about 10 mm from one another.
15. The seaweed cultivation substrate according to claim 11 , wherein the first cord is in the form of at least one rope, and the at-least one rope is wrapped around at least a portion of the external surface of the core.
16. The seaweed cultivation substrate according to claim 11 , wherein the first cord is in the form of at least one ribbon, and the at-least one ribbon is wrapped around at least a portion of the external surface of the core.
17. The seaweed cultivation substrate according to claim 1 , wherein the cultivation substrate is in the form of a braid including at least one second cord and at least one first cord.
18. The seaweed cultivation substrate according to claim 1 , wherein the cultivation substrate is in the form of a covered yarn including at least one first cord and at least one second cord.
19. The seaweed cultivation substrate according to claim 11 , wherein repeating portions from about 0.9 mm to about 1.1 mm of the external surface of the core are not covered by the first cord.
20. The seaweed cultivation substrate according to claim 11 , wherein repeating portions from about greater than 1.0 mm of the external surface of the core are not covered by the first cord.