Small burrowing amphipods cause major damage in a large kelp.

Large herbivores such as sea urchins and fish consume a high proportion of benthic primary production and frequently control the biomass of marine macrophytes. By contrast, small mesograzers, including gastropods and peracarid crustaceans, are abundant on seaweeds but have low per capita feeding rates and their impacts on marine macrophytes are difficult to predict. To quantify how mesograzers can affect macrophytes, we examined feeding damage by the herbivorous amphipods Sunamphitoe lessoniophila and Bircenna sp., which construct burrows in the stipes of subtidal individuals of the kelp Lessonia berteroana in northern-central Chile, southeast Pacific. Infested stipes showed a characteristic sequence of progressive tissue degeneration. The composition of the amphipod assemblages inside the burrows varied between the different stages of infestation of the burrows. Aggregations of grazers within burrows and microhabitat preference of the amphipods result in localized feeding, leading to stipe breakage and loss of substantial algal biomass. The estimated loss of biomass of single stipes varied between 1 and 77%. For the local kelp population, the amphipods caused an estimated loss of biomass of 24-44%. Consequently, small herbivores can cause considerable damage to large kelp species if their feeding activity is concentrated on structurally valuable algal tissue.

Chemical composition and heavy metal content of Chilean seaweeds: Potential applications of seaweed meal as food and feed ingredients.

Seaweeds are a rich source of nutritional and functional compounds, but they also accumulate heavy metals. Here, the chemical composition (crude protein, total lipids, Nitrogen Free Extract and fiber) and the presence of minerals (Na, K, Ca, Mg, P, Fe, Mn, Cu, Zn, Mo, Se) and unwanted elements (As, Cd, Hg, Pb, Ni, Cr, Al) were determined in eleven seaweeds from Chile. Depending on the species, a good contribution to the Recommended Dietary Allowance for K, Ca, Mg, Fe, Mn and Se was observed, and low Na/K ratios (<1.0) as well. The health risk assessment indicated low hazard due to intake of seaweed meal. The mean values of As, Hg, and Pb were below the maximum limits set for food supplements and feed ingredients. The seaweeds studied have a suitable chemical composition for their uses as food and feed ingredients, although Cd levels should be monitoring especially in brown seaweeds.

Citizen scientists study beach litter along 12,000 km of the East Pacific coast: A baseline for the International Plastic Treaty.

Anthropogenic Marine Litter (AML) accumulating on beaches causes damage to coastal ecosystems and high costs to local communities. Volunteers sampled AML on 130 beaches along the central and southern East Pacific coasts, with AML densities ranging from 0.46 to 2.26 items m-2 in the different countries. AML composition was dominated by plastics and cigarette butts, the latter especially in Mexico and Chile. The accumulation of AML in the upper zones of the beaches and substantial proportions of cigarette butts, glass and metal pointed mainly to local sources. Statistical modelling of litter sources on continental beaches revealed that tourism, access and related infrastructure (e.g. parking lots) best explained AML densities, while plastic densities were also influenced by the distance from river mouths and national Gross Domestic Product. Large-scale monitoring can be a useful tool to evaluate the effectiveness of public policies that should primarily focus on land sources.