First records of hydroid epibionts on the introduced macroalga Gracilariaparvispora in the Mexican Pacific.

Background: The red macroalga Gracilariaparvispora is an introduced species in the Mexican Pacific. To date, there are no published studies on its sessile epibionts, including the hydrozoans and bryozoans, which are the dominant epibionts on macrophytes and of significant biological and economic interest. New information: This study provides insight into the faunal diversity of hydroids growing on G.parvispora. A total of 185 thalli from both herbarium specimens and field samples collected from five sites in La Paz Bay were revised. Each thallus size and the presence of hydroid epibionts in each thallus region were registered. Eight different hydrozoan taxa were growing on the red macroalgae, including the first recorded observation of Obeliaoxydentata in the Gulf of California. The sizes of the collected thalli were mostly under 7.0 cm, the maximum number of taxa per thallus was three and the thallus region containing the highest number of epibionts was in the middle. Significant differences were observed amongst the lengths of thalli with and without epibionts. The thalli with epibionts were larger than the thalli without epibionts. Similarly, significant differences were observed amongst the months. The pair-wise test revealed that each month exhibited distinctive epibiont taxa when compared to the others. This study highlights the lack of information on these associations. Further research is needed to understand whether introduced macroalgae can bring non-native epibiont species to an area.

Trace metals pollution and trophic position of three sea urchin species in the Gulf of California.

Sea urchin species are ecologically important in the Gulf of California and are becoming popular as a local fishery due to their commercial value. The most abundant species are Echinometra vanbrunti, Eucidaris thouarsii, and Tripneustes depressus. The objective of this study was to evaluate cadmium, lead, copper, zinc, and iron concentrations, as well as stable isotope values in these sea urchin species in the Santa Rosalia mining area (STR), in three sites: Punta Gorda, Punta el Aterrizaje, and Punta Salina. The highest Fe concentration (100.2 mg kg-1) was found in E. vanbrunti, while the highest concentrations of Pb (15.1 mg kg-1), Cu (14.5 mg kg-1), and Zn (347.7 mg kg-1) were recorded in E. thouarsii, and the highest Cd concentration (10.8 mg kg-1) was found in T. depressus. The main health risk of trace metal pollution in STR may be caused by Cd and Pb. δ15N and δ13C values were higher in E. thouarsii and T. depressus, respectively; E. thouarsii has the highest trophic position. Specimen size was not related to metal concentrations, but a positive relationship was observed between specimen size and isotopic values in T. depressus. The three species showed different bioaccumulation patterns for the metals analyzed. Additionally, collection sites and seasons play an important role in the variability of metal concentration.

A survey of epibiont hydrozoans on Sargassum.

The brown alga Sargassum provides a natural substrate occupied by hydrozoans in shallow marine waters. A global count in 2007 listed 39 epibiotic species of Hydrozoa growing on Sargassum, but more studies have been published since, therefore, an update is timely, particularly due to the increased abundance of Sargassum in the Caribbean. This review, based on a recent literature survey and new records from Mexico, includes 133 publications of epibiotic hydrozoans on Sargassum spanning 220 years, from 1802 to 2022. A total of 131 hydrozoan species were recorded on 26 species of Sargassum, most belonging to the subclass Hydroidolina (130), with only one record of a trachyline medusa (Gonionemus vertens, subclass Trachylinae). Most publications centered on the Tropical Atlantic, where the greatest number of hydrozoan species (67 species) were recorded. All hydrozoan species possess a hydrorhiza, except one hydromedusae species that attach to Sargassum via adhesive tentacles. Most of the hydrozoan species associated with Sargassum exhibited a benthic life cycle (93 species) and are comprised of erect, branched colonies (67 species) and large hydrothecae (69 species). Although the number of studies of epibiotic hydrozoans on Sargassum has increased since the mid-20th century, nevertheless hydrozoan richness has not reached an asymptote. Therefore, more sampling of Sargassum species would likely identify more hydrozoan species associated with Sargassum, especially among benthic Sargassum, and might help reveal potential biogeographical and ecological patterns between Sargassum and hydrozoan epibionts.

Marine algal flora of São Miguel Island, Azores.

BACKGROUND: The macroalgal flora of the Island of São Miguel (eastern group of the Azores Archipelago) has attracted the interest of many researchers in the past, the first publications going back to the nineteenth century. Initial studies were mainly taxonomic, resulting in the publication of a checklist of the Azorean benthic marine algae. Later, the establishment of the University of the Azores on the Island permitted the logistic conditions to develop both temporal studies and long-term research and this resulted in a significant increase on research directed at the benthic marine algae and littoral communities of the Island and consequent publications.Prior to the present paper, the known macroalgal flora of São Miguel Island comprised around 260 species. Despite this richness, a significant amount of the research was never made public, notably Masters and PhD theses encompassing information regarding presence data recorded at littoral and sublittoral levels down to a depth of approximately 40 m around the Island and the many collections made, which resulted in vouchers deposited in the AZB Herbarium Ruy Telles Palhinha and the LSM- Molecular Systematics Laboratory at the Faculty of Sciences and Technology of the University of the Azores.The present publication lists the macroalgal taxonomic records, together with information on their ecology and occurrence around São Miguel Island, improving the knowledge of the Azorean macroalgal flora at local and regional scales. NEW INFORMATION: A total of 12,781 specimens (including some identified only to genus) belonging to 431 taxa of macroalgae are registered, comprising 284 Rhodophyta, 59 Chlorophyta and 88 Ochrophyta (Phaeophyceae). Of these, 323 were identified to species level (212 Rhodophyta, 48 Chlorophyta and 63 Ochrophyta), of which 61 are new records for the Island (42 Rhodophyta, 9 Chlorophyta and 10 Ochrophyta), one an Azorean endemic (Predaea feldmannii subsp. azorica Gabriel), five are Macaronesian endemisms (the red algae Botryocladia macaronesica Afonso-Carrillo, Sobrino, Tittley & Neto, Laurencia viridis Gil-Rodríguez & Haroun, Millerella tinerfensis (Seoane-Camba) S.M.Boo & J.M.Rico, Phyllophora gelidioides P.Crouan & H.Crouan ex Karsakoff and the green alga Codium elisabethiae O.C.Schmidt), 19 are introduced species (15 Rhodophyta, two Chlorophyta and two Ochrophyta) and 32 are of uncertain status (21 Rhodophyta, five Chlorophyta and six Ochrophyta).