Under controlled laboratory conditions, juvenile green abalone Haliotis fulgens were fed rehydrated natural feeds to determine the effects on growth, survival, feed efficiency and biochemical composition of the digestive gland and muscle. Five macroalgae, Ulva sp. (Chlorophyta), Eisenia arborea, Macrocystis pyrifera, Egregia menziesii (Phaeophyta) and Porphyra perforata (Rhodophyta) were tested. The macroalgae promoted growth, although, depending on the species, there were considerable differences in growth, feed efficiency and biochemical composition of the digestive gland and muscle. Mean growth rate in length and weight and survival rate varied within the ranges 1.6–15.1 μm day−1, 1.4–8.1 mg day−1 and 44–69%, respectively. Significantly, higher growth rates were obtained from Egregia menziesii, M. pyrifera and P. perforata. Feed conversion ratio ranged from 6.5 to 42.4 for P. perforata and Ulva sp. Protein, carbohydrates and lipid contents in the digestive gland ranged from 113 to 180, 98.3 to 448 and 17.2 to 23.3 mg g−1, respectively. In muscle, the ranges were 66.9–123, 9.5–23.2 and 2.8–3.9 mg g−1, respectively. This study shows that rehydrated Egregia menziesii, M. pyrifera and, particularly, P. perforata are more efficient in promoting growth than Ulva sp. and E. arborea which match results reported by other authors when using the same fresh macroalgae.

Initial spread of the invasive green alga Caulerpa verticillata over coral reef communities in the Gulf of California Caulerpa verticillata J. Agardh 1847 (Bryopsidales, Caulerpaceae) is an invasive and aggressive algal species that quickly spreads by extensive blooms and overgrows coral colonies until the corals are completely covered (Lapointe and Bedford 2010). Like other species in this genus, this alga has the potential to impact ecosystem diversity and function of coral reefs (Fernández and Cortés 2005; Kružić et al. 2008). In the tropical Eastern Pacific, this species has been reported only in Panama at 8°N and in the Mexican Pacific at 19°N (Mateo-Cid and Mendoza-González 1991; Pérez-Justavino et al. 2010). Little is known about the spread of this alga. In January 2010, C. verticillata (Fig. 1a) was recorded for the first time covering a few square meters in rocky areas at 2 m depth at Esterito (24°10¢36.46 †N, 110°18¢21.16 †W) and La Concha (24°12¢4.72 †N, 110°18¢2.24 †W), in the southwestern part of the Gulf of California. One year later, diver and aerial surveys revealed that the alga had increased its coverage at the same two locations~200,700 and~11,000 m 2 , respectively. In November 2011, the alga was found at Palmira (24°11¢18.52 †N, 110°18¢12.00 †W), cov-ering~30,000 m 2 at 0.5-7 m depth and growing on a coral reef community (Fig. 1b). Algal growth occurred between branches of Pocillopora damicornis (Fig. 1c) and over P. damicornis and Porites panamensis colonies (Fig. 1d,e). Surveys of 12 sites (from 24.04°N to 24.74°N) between 2010 and 2012 indicated that C. verticillata so far remains limited to the three sites above. This is the first report of C. verticillata overgrowing coral reef communities in the Gulf of California. This finding emphasizes that regular reef monitoring will be necessary to evaluate the effects of this algal invasion on coral populations in this region.

We describe the assemblage of cyanobacteria and macroalgae on Avicennia germinans pneumatophores, Rhizophora mangle aerial roots, and within the tidal channel of a mangrove located in a lagoon bordering the east coast of the Baja California Peninsula, from samples collected every 2 months from May 2005 to May 2006. A total of 68 species were found: 21 cyanobacteria, 1 Xanthophyta, 25 Chlorophyta, 1 Ochrophyta-Phaeophyceae, 19 Rhodophyta, and 1 Anthophyta. Species richness varied between habitats; pneumatophores supported 29 species of algae, aerial roots supported 20 species of algae, and the channel bottom supported 46 species. Taxa common to the three habitats were Lyngbya sp., Vaucheria sp., Boodleopsis pusilla, Rhizoclonium riparium, and Bostrychia radicans. Mean wet weight algal biomasses on aerial roots and in the channel were 494 g root-1and 12,924 g m-2, respectively. The dominant species on aerial roots and on the channel bottom were Caulerpa sertularioides, Gracilariopsis lemaneiformis, and Spyridia filamentosa. The channel bottom also had Vaucheria sp. and two cyanobacteria (Oscillatoria sp. and Lyngbya sp.). Morphotypes of two cyanobacteria (Heteroleibleinia sp. and Johanesbaptistia sp.) are recorded in this habitat for the first time.

The first record of the amphioxus Branchiostoma californiense on seagrass patches of Halodule wrightii in the Gulf of California is reported. Sixty individuals (19 males, 18 females, and 23 undifferentiated) were collected in May 2017 at Bahía Balandra, Gulf of California, from subtidal seagrass patches at a depth of 0.5 m at low tide. The length and weight ranged from 15.88–28.44 mm and from 0.01–0.11 g for females and 11.7–27.9 mm and 0.01–0.09 g for males, respectively. The minimum size of sexually mature individuals was 11.70 mm for males and 15.88 mm for females; 62% of the specimens were sexually mature. Analysis of the total length-weight relationship suggested an allometric growth pattern among females, males and undifferentiated individuals, whereas an analysis of the entire sample suggested an isometric growth pattern. Typical and additional morphological characters were used to identify the amphioxi. High morphological variability between individuals was found, suggesting the presence of several morphotypes. Branchiostoma californiense had been previously reported as exclusively associated with bare sandy areas, but our study shows that this species can also be found in seagrass patches, using them as breeding and feeding grounds. Thus, seagrass patches are evidenced as suitable habitats for amphioxus.

Reportamos la depredación de aves acuáticas migratorias por Caracara cheriway. El 4 de enero del 2015 se observó a un caracara juvenil alimentándose de Egretta thula (juvenil) y a un caracara adulto de Podiceps nigricolis (adulto) en una playa al sur de la península de Baja California. Este es el primer reporte de Caracara cheriway depredando presas vivas de aves acuáticas migratorias.

An on-water remote monitoring robotic system was developed for indirectly estimating the relative density of marine cyanobacteria blooms at the subtidal sandy-rocky beach in Balandra Cove, Baja California Sur, Mexico. The system is based on an unmanned surface vehicle to gather underwater videos of the seafloor for avoiding physical damage on Anabaena sp. cyanobacteria colonies, which grow in tufts of filaments weakly attached to rocks, seagrass, and macroalgae. An on-axis image stabilization mechanism was developed to support a camcorder and minimize wave perturbation while recording underwater digital images of the seafloor. Color image processing algorithms were applied to estimate the patch coverage area and density, since Anabaena sp. filaments exhibit a characteristic green tone. Results of field tests showed the feasibility of the robotic system to estimate the relative density, distribution, and coverage area of cyanobacteria blooms, preventing the possible impact of direct observation. The robotic system could also be used in surveys of other benthos in the sublittoral zone.

One of the bottlenecks in cultivating juvenile green abalone Haliotis fulgens is the lack of well-adapted natural or formulated food for optimal growth.

No abstract