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Nets in traditional Porphyra mariculture are seeded with conchospores derived from the conchocelis phase, and spend a nursery period in culture tanks or calm coastal waters until they reach several centimeters in length. Some species of Porphyra can regenerate the foliose phase directly through asexual reproduction, which suggests that the time, infrastructure, and costs associated with conchocelis culture might be avoided by seeding nets with asexual spores. Here, we present work from a short-term mariculture study using nets seeded with asexual spores (neutral spores) of a native Maine species of Porphyra. Porphyra umbilicalis (L.) Kutzing was selected for this proof of concept research because of its reproductive biology, abundance across seasons in Maine, and evidence of its promise as a mariculture crop. We studied the maturation, release, and germination of the neutral spores to develop an appropriate seeding protocol for nets, followed by development of a nursery raceway to provide an easily manipulated environment for the seeded nets. Neutral spores were produced throughout the year on the central Maine coast,however, there was a temporal variability in the number and survival of released neutral spores, depending upon thallus position in the intertidal zone. Small thalli were strictly vegetative, but most thalli reproduced by neutral spores- sexual reproduction was absent. Neutral spores germinated quickly at 10 and 15 'C, but germination was delayed at 5 degrees C. Unlike some algal zygotes and spores, neutral spores of R umbilicalis required light to germinate; however, irradiances of 25 and 100 mu mol photons M-2 S-1 were equally sufficient for germination. Rafts of seeded nets were deployed in Cobscook Bay, Maine, at two distances from salmon aquaculture pens and at a control site on a nearby, fallow aquaculture site (no salmon). There was no difference in nitrogen content of harvested thalli; however, both the density and the surface area of harvested thalli were different among the sites. The possible causes of these differences are discussed in the context of potential use of Pumbilicalis in IMTA.

High growth rates and temporal or spatial opportunism are considered central to the success of filamentous algae, in particular for escaping or minimising the effects of herbivory. However, the role of chemical defences in filamentous algae has received far less attention. We investigated possible chemical feeding deterrence by filamentous red algae that have conspicuous cellular inclusions (Asparagopsis armata, Anotrichium tenue and Balliella amphiglanda) and 2 others without inclusions (Callithamnion korfense and Ulva sp.). The 3 algae with cellular inclusions were consumed at lower rates by a generalist amphipod, Hyale nigra, than the other 2 algae. To determine the potential role of chemical defences for A. armata, we conducted tests against herbivores using algae in which the production of halogenated metabolites was manipulated. This manipulation had no effect on carbon and nitrogen values of the algae, and allowed us to directly test the role of algal secondary metabolites in defence against herbivores without using artificial diets. Bromide (+) algae (with halogenated metabolites) deterred grazing by 2 mesograzers (Hyale nigra and juvenile abalone Haliotis rubra), which consumed up to 4 times more bromide (–) (metabolite-free) algae than bromide (+) algae. Juveniles of the sea hare Aplysia parvula were not deterred by the chemical defences in bromide (+) A. armata. In field assays, artificial diets containing a crude extract of A. armata were also active against herbivores. Although functional form models typically predict that tolerance—not resistance—should be the key defensive strategy for marine algae with simple architecture, this study demonstrates that resistance traits may also be important and more broadly utilised in filamentous species.

Seaweeds, otherwise known as marine algae are primitive non-flowering photosynthetic macrophytes occurring in tidal regions of seas and oceans that occupy 71% of the globe and they are natural renewable resources. Green, brown and red seaweeds are generally distributed in the intertidal, tidal and subtidal regions respectively. Seaweed production through aquaculture in the world was 11.66, 16.83 and 19.90 million tons (fresh) in 2002, 2008 and 2010 respectively and in 2012 it was 23.78 million tons (fresh). Kappaphycus alvarezii production in the world was 1,83,000 tons (dry) in 2010 while it was 1, 490 tons (fresh) during the same period in India. Seaweeds formed part of human life from time immemorial and served as food, besides their use as feed, fodder and manure. Some of the edible seaweeds include species of Porphyra, Palmaria, Undaria, Laminaria, Monostroma and Caulerpa and possess desirable quantities of proteins, carbohydrates, fibre, minerals and vitamins, besides having biological compounds to combat diseases. Ascophyllum sp, Macrocystis sp, Laminaria sp, Alaria sp, Palmaria sp and Pelvetia sp are some of seaweeds used as fodder. Seaweeds are the only natural source for hytochemicals viz; agar, algin and carrageenan which have wide applications in various ways in day to day life of human beings. Species of Gelidium, Gracilaria, Pterocladia, Gelidiella, Ahenpeltia and Acanthopeltis are some agarophytes, while those of Laminaria, Macrocystis, Ascophyllum, Durvillea, Ecklonia and Sargassum are some alginophytes. Carrageenophytes include species of Chondrus, Gigartina, Sarcothalia, Eucheuma and Kappaphycus. The alginophytes mentioned here also serve as manure because they contain macronutrients (N, P, K, Ca, Mg, S), micronutrients (Zn, Cu, Mn) and growth regulators (auxins, gibberlins, cytokinins) necessary for plant growth.

Seaweeds-products, processing and utilization Marine macroalgae which are popularly termed as Seaweeds belong to the primitive group of nonflowering plants known as Thallophyta. They are autotrophic plants and grow in the intertidal and subtidal regions of the sea.