Seaweed resources of Mexico: current knowledge and future perspectives

High diversity of marine macroalgae is reported for Mexican coasts, including numerous endemic species. Seaweed research in Mexico has focused on the northern regions of the Pacific coast (Temperate Pacific and Gulf of California) and on the Mexican Caribbean coast, leaving aside other regions (Tropical Pacific and Gulf of Mexico). Utilization of seaweed resources within the country has been based on artisanal collection of wild populations mainly for polysaccharide extraction, fertilizers, raw material for animal feed and cosmetic products. The main exploitation has occurred along the coasts of Baja California peninsula, based on few species (Gelidium robustum, Macrocystis pyrifera, Chondracanthus canaliculatus and Gracilariopsis lemaneiformis). Governmental regulations for management have allowed harvesting to reach approximately 11,500 wet tons per year (2013–2016). Nevertheless, in recent years (2014–2016) the total seaweed import volume has increased (5302 tons per year in average) over the export volume (2156 tons per year in average), suggesting a notably growing demand for seaweed resources in the country and representing an opportunity for investment projects. Several pilot studies on seaweed cultivation in Mexico propose that sustainable aquaculture techniques could complement the harvest in natural populations and ensure a homogeneous production with high quality in the long term.

Estimation of maximum sustainable yield of Gelidium robustum seaweed fishery in Mexico

Surplus production models were used to assess the fishery condition of red seaweed Gelidium robustum off the west coast of the Baja California Peninsula from 1985 to 1997. The maximum sustainable yield and optimum effort estimated by the Schaefer model were 705 tn and 457 teams, while the Fox model estimated 670 tn and 510 teams. The determination coefficients were r2=0·62 for the Fox and r2=0·58 for the Schaefer model. These results suggest that the resource is not overexploited. Fitting the data to Hilborn & Walters' dynamic model was not satisfactory.

Determination of preferred habitats of early benthic juvenile California spiny lobster, Panulirus interruptus, on the Pacific coast of Baja California Sur, Mexico

The habitat requirements of early benthic stage juveniles of California spiny lobster Panulirus interruptus are known only from studies conducted near its northernmost geographic range, where environmental conditions differ markedly from those along the Pacific coast of the southern Baja California Peninsula (Mexico). We determined the natural habitat of this stage of P. interruptus in the central portion of their range from sampling the available dominant vegetated habitats included various seagrasses and macroalgae. Additionally, experiments on habitat selection by early benthic juvenile P. interruptus were performed under laboratory conditions to test natural substrate selection and whether selection of substrata is affected by odour signals. Despite the abundance of different macrophytes as habitat, 93% of the juvenile lobsters were found at the base of the blades of Phyllospadix spp. in the intertidal zone at 0 to 3 m. The highest juvenile densities were found in September at both sites. In laboratory experiments, juvenile lobsters preferred, in order of preference, Gelidium robustum, Phyllospadix, Plocamium pacificum, and holdfasts of the kelp Macrocystis pyrifera. A second laboratory experiment showed that these preferences were affected by odour signals. Results indicate that the ecology of juvenile P. interruptus off the coast of the Mexican Baja is similar to that observed off the coast of southern California.

REGISTRO DE TALLA RECORD PARA Gelidium robustum (Gardner) Hollenberg et Abbott (GELIDIALES, RHODOPHYTA) EN LA COSTA PACÍFICO DE MÉXICO

During the harvest on the beds of "sargazo rojo" along the Baja California Sur coast, several specimens of Gelidium robustum (Gardner) Hollenberg et Abbott were collected which represented a new size record (180 cm) for this species. Record size for Gelidium robustum (Gardner) Hollenberg et Abbott (Gelidiales, Rhodophyta) in the Pacífic coast of México

Population dynamics of Caulerpa sertularioides (Chlorophyta: Bryopsidales) from Baja California, Mexico, during El Niño and La Niña years

This study monitored the abundance of the tropical/subtropical seaweed Caulerpa sertularioides (Chlorophyta: Bryopsidales) from a sandy beach from Balandra Cove, on the south-eastern coast of the Baja California Peninsula, Mexico, between April 1998 and April 2000, including consecutive El Niño and La Niña events. El Niño conditions, indicated by relatively high seawater temperatures, were associated with a high population abundance (April–June 1998), whereas La Niña conditions, indicated by relatively low temperatures, were associated with the absence of C. sertularioides (April–June 1999 and April 2000). Caulerpa sertularioides was present during other times of the year during the study period, but never with the high abundance reached during El Niño conditions. Seaweeds of temperate affinity occurring in Baja California, such as Gelidium robustum (Rhodophyta: Gelidiales) and Macrocystis pyrifera (Phaeophyceae: Laminariales), decreased sharply in abundance during El Niño conditions. Therefore, the biogeographic affinity of seaweeds from Baja California might be helpful in predicting the effects of El Niño and La Niña on their abundance, with implications for resource management and for the prediction of the effects of long-term oceanographic changes on seaweed distribution.