Volume 65, Issue 3

Skeletonema species are among the most important components of phytoplankton communities in the temperate and tropical Pacific Ocean. Data on Skeletonema species diversity and abundance in the northeastern Pacific are fragmentary. The long-term observations (1996–2019) of the phytoplankton from the coastal waters of the northwestern Sea of Japan resulted in five Skeletonema species being recorded: Skeletonema costatum , S. dohrnii , S. japonicum , S. marinoi and S. menzelii. For each of the species, a morphological description is provided based on electron microscopy. Ecological factors influencing the distribution of the species and their occurrence under certain environmental parameters are discussed. One of the species, S. menzelii , is a new record for Russia. Skeletonema costatum was confirmed to occur in the study area. Seasonal and interannual changes in the abundance of Skeletonema species were studied. The concentrations of the species varied from 20 cells l −1 to 12,700,000 cells l −1 . From 1996 to 2018 there was a downward trend in the numbers of Skeletonema . Skeletonema japonicum was noted for the first time to bloom. Skeletonema dohrnii formed summer blooms; S. japonicum bloomed in the autumn. No Skeletonema blooms were detected in the winter months.

Three new species of the red algal genus Asteromenia (Hymenocladiaceae, Rhodophyta) are described based on morphological and molecular analyses. DNA analyses of recent collections of topotype specimens of A. examinans from the Houtman Abrolhos Islands (Western Australia) have revealed that the specimens used in earlier studies were misidentified and represent an undescribed species, herein described as A. juliannae . Two additional new species, A. crenulata and A. praetermissa are described from the Cocos (Keeling) Islands, and Norfolk Island, respectively. For the most part, the new species showed morphological overlap and could not be discriminated based on morphology alone; DNA sequencing is therefore considered essential for accurate species recognition. The potential for misidentification of morphologically similar specimens highlights the need for sequence analyses and reference barcoding to be based on type or topotype specimens. The adoption of molecular methods in alpha taxonomy has led to the recognition of considerable diversity in the Rhodymeniales and it is envisaged that further collecting will add even more taxa to Australia’s rich algal flora.

Large-scale farming of Undaria pinnatifida is conducted in northern China. Conspicuous natural populations of this alga are distributed on rocky shores in this region. However, the genetic relationship between U. pinnatifida from China and native populations in other countries remains largely uncertain. We obtained sequences for the mitochondrial cox3 and tatC–tLeu regions and the internal transcribed spacer one of nuclear ribosomal DNA from representative natural and farmed populations of U. pinnatifida in China. We analyzed genetic diversity, and evaluated the genetic relationship between Chinese populations and Japanese and Korean populations. The mitochondrial and nuclear DNA sequences revealed high genetic diversity in most Chinese populations. Unique mitochondrial haplotypes were detected in the Gouqi Island population consistent with historical records of a native population on the island. Phylogenetic analyses derived from the mitochondrial DNA sequences revealed that the Chinese samples were classifiable as the Continental and Northern Japan types. All natural populations from rocky reefs in northern China were grouped with the Continental type and all farmed populations with the Northern Japan type. Mitochondrial and nuclear DNA sequences revealed significant genetic differentiation between the farmed populations and adjacent natural populations from rocky reefs, in agreement with previous results obtained using microsatellites.

The purpose of this study was to develop stable microsatellite markers and evaluate the genetic background of cultivated Sargassum fusiforme. Based on the transcriptome data obtained by high-throughput sequencing, eleven polymorphic microsatellite markers were developed using four S. fusiforme populations from China. One cultivated population was from Dongtou (DT) and three wild populations were from Muye Island (MY), Pingyu Island (PY) and Nanji Island (NJ). The cultivated S. fusiforme had the highest genetic diversity, with 90.91% polymorphic loci and Shannon’s information index ( I ) of 0.606, which were much higher than those of the wild populations ( I  = 0.425). The four populations were divided into two groups through a structure analysis. DT, PY and NJ were clustered into a group, and MY was an almost completely separate group. Both the structure and principal coordinates analysis showed that DT and PY had the lowest genetic differentiation, suggesting that the parents of the breeding population in Dongtou partly come from Pingyu Island. The observed heterozygosity of NJ was much higher than expected, indicating that the NJ wild resource was greatly affected by the environment. These eleven microsatellite markers could provide additional markers for germplasm resource evaluations and facilitate genetic analyses of the S. fusiforme population.

Peru is the second largest seaweed producer in the Americas. Nevertheless, the actual extent and trends of exports of various seaweeds are not known. This study is the first to summarize and analyze the official seaweed export statistics for Peru, which cover 1995–2020. Total exports showed a considerable increase from 2008, reaching their highest historical volume in 2019 (33,948 metric tons dry weight plus 3 metric tons of fresh/frozen weight). China dominated the market by importing 90% of the total Peruvian production of seaweeds. A low percentage of the exports (3%) corresponded to red seaweeds (mainly Chondracanthus chamissoi for industrial use). Export volumes of C. chamissoi have been decreasing since 2015, however prices have continued to increase. Brown seaweeds accounted for 97% of the exports. These were dominated by Lessonia berteroana until 2007 and then by Macrocystis pyrifera . The latter showed the highest overall growth rate (47%). Wet biomass estimations showed a gap between the data reflecting what is officially harvested versus what is actually exported. This “unreported biomass” might reflect the government’s lack of control of seaweed harvesting. Finally, the COVID-19 pandemic showed a negative impact on exports with M. pyrifera being the most affected species.