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Aquaculture is currently the fastest growing animal food production sector and will soon supply more than half of the world’s seafood for human consumption. Continued growth in aquaculture production is likely to come from intensification of fish, shellfish, and algae production. Intensification is often accompanied by a range of resource and environmental problems. We review several potential solutions to these problems, including novel culture systems, alternative feed strategies, and species choices. We examine the problems addressed; the stage of adoption; and the benefits, costs, and constraints of each solution. Policies that provide incentives for innovation and environmental improvement are also explored. We end the review by identifying easily adoptable solutions and promising technologies worth further investment.

Minicoy lagoon harbours extensive beds of Thalassia hemprichii in association with Syringodium isoetifolium, Halophila ovalis and Halodule uninervis. The total area occupied by seagrass flat ranges from 2.0 to 2.2 sq.km. Net primary production (NPP) of seagrass species varied from 5.0 gC/m³/day (0.5 gC/kg (wet wt.)/day for Syringodium to 10 gC/m³/day (1.0 gC/kg (wet wt.)/day for Halodule. It was estimated that an impairement up to 50 % on the NPP of Thalassia plants was caused by the prolonged exposure of the beds to bright sunshine in the intertidal areas during ebb stage when compared to those Thalassia plants growing in the unexposed habitats. Wet biomass, density of seagrass species and their NPP potential on the community metabolism of the lagoon are discussed.

PROBLEM: Climate change, coastal development, and pollution are destroying America’s coastal marine ecosystems. Florida has lost over 50 percent of its coral reefs since 1996.20 Northern California has lost 93 percent of its kelp forest since 2013.21,22 Not only are our coastal ecosystems habitat for most seafood species at some phase of their life, but they also provide critical storm protection – wetlands prevented $625 million in damages during Hurricane Sandy and are often more effective and less expensive than seawalls.23 A concerted ecosystem restoration effort is needed to protect coastal areas, especially poor communities, communities of color, and Indigenous nations which are most at risk.

SOLUTION: Support state and national restoration programs, including replanting of seagrasses, wetlands, mangroves, shellfish, and seaweeds, perhaps funded by a blue carbon fund.  

Sea-urchin feeding fronts are a striking example of spatial pattern formation in an ecological system. If it is assumed that urchins are asocial, and that they move randomly, then the formation of these dense fronts is an apparent paradox. The key lies in observations that urchins move further in areas where their algal food is less plentiful. This naturally leads to the accumulation of urchins in areas with abundant algae. If urchin movement is represented as a random walk, with a step size that depends on algal concentration, then their movement may be described by a Fokker–Planck diffusion equation. For certain combinations of algal growth and urchin grazing, traveling wave solutions are obtained. Two-dimensional simulations of urchin algal dynamics show that an initially uniformly distributed urchin population, grazing on an alga with a smoothly varying density, may form a propagating front separating two sharply delineated regions. On one side of the front algal density is uniformly low, and on the other side of the front algal density is uniformly high. Bounds on when stable fronts will form are obtained in terms of urchin density and grazing, and algal growth.