Temperate Kelp Forest Collapse by Fish Herbivory: A Detailed Demographic Study

[Abstract] Kelps dominate rocky shores in temperate latitudes, acting as important foundation species. Recently, kelp forests have received growing attention for their decline around the world. Climate change is one of the main drivers of their deforestation, both through abiotic stress and/or distortion of biotic interactions. In NW Spain, golden kelp (Laminaria ochroleuca) forests have recently declined in some areas due to excessive grazing. To further investigate the mechanisms behind this decline, a thorough 1-year seasonal demographic study was carried out on eight golden kelp reefs: four healthy and four degraded by herbivory. Kelps covered the full range of size classes throughout the year on healthy reefs. By contrast, only small, newly recruited kelps were found on degraded reefs in spring-summer, because excessive herbivory in autumn-winter caused a total collapse of kelp populations on a reef-scale (i.e., all kelps reduced to inviable stubs with no blade and no growth meristem). Bite marks in kelps covering all size classes showed that fishes, instead of invertebrates, were the culprits of the excessive herbivory. Recent studies, mostly conducted in the Indo-Pacific, also found that fish herbivory, alone or in combination with abiotic stressors, can maintain a canopy-free state in kelp reefs. To the best of our knowledge, this is the first time that fish is also shown to cause the collapse of entire kelp forests on a reef scale in the temperate Atlantic. The implications of this finding for the management and potential recovery of degraded reefs are discussed.This research was funded by the “Fundación Biodiversidad y el Ministerio de Transición Ecológica y el Reto Demográfico.” BioCost Research Group acknowledges funding from Xunta de Galicia (grants ED431D 2017/2020 and ED431B 2018/49 of “Axudas para a consolidación e estructuración de unidades de investigación competitivas do SUG” program). SB received financial support from the Xunta de Galicia and the European Union (European Social Found – ESF) (grant ED481A-2018/101). CP-C received financial support from Xunta de Galicia “Axudas de apoio á etapa de formación posdoutoral “(grant ED481B-2021/095)”Xunta de Galicia; ED431D 2017/2020Xunta de Galicia; ED431B 2018/49Xunta de Galicia; ED481A-2018/101Xunta de Galicia; ED481B-2021/09

Could the Annual Saccorhiza Polyschides Replace a Sympatric Perennial Kelp (Laminaria Ochroleuca) When It Comes to Supporting the Holdfast-Associated Fauna?

[Abstract] Kelp forests dominate temperate rocky shores worldwide but are declining globally with consequences for organisms that depend on them. In NW Iberia, the golden kelp (Laminaria ochroleuca) commonly occurs alongside a fast-growing annual that, unlike the golden kelp, does not seem to have receded in recent times (Saccorhiza polyschides). Here, we assessed whether the bulbous holdfast of S. polyschides could replace the intricate holdfast of L. ochroleuca as epifaunal habitat provider. Richness, diversity and total abundance of epifauna was similar in both seaweeds, while colonial/encrusting fauna was more abundant in L. ochroleuca. More importantly, each host supported a distinctive assemblage structure, indicating that S. polyschides seems an unsuitable replacement for L. ochroleuca as habitat provider for holdfast epifauna. Therefore, while S. polyschides may contribute substantially to the kelp forest canopy in some seasons, a regional decline of L. ochroleuca will likely alter the patterns of biodiversity within kelp stands.This research was funded by the “Fundación Biodiversidad y el Ministerio de Transición Ecológica y el Reto Demográfico.” BioCost Research Group acknowledges funding from Xunta de Galicia (grant ED431B 2021/32 of “Axudas para a consolidación e estructuración de unidades de investigación competitivas do SUG” program). SB received financial support from the Xunta de Galicia and the European Union (European Social Found – ESF) (grant ED481A2018/101). CP-C received financial support from Xunta de Galicia “Axudas de apoio á etapa de formación posdoutoral “(grant ED481B-2021/095)”Xunta de Galicia; ED431B 2021/32Xunta de Galicia; ED481A2018/101Xunta de Galicia; ED481B-2021/09

Structure and Trophic Niches in Mobile Epifauna Assemblages Associated With Seaweeds and Habitats of Syngnathid Fishes in Cíes Archipelago (Atlantic Islands Marine National Park, North West Iberia)

[Abstract] Syngnathids are vulnerable fishes closely associated with seaweeds and seagrass, which provide shelter and food resources. Even though most syngnathids commonly feed on small crustaceans, the feeding regimes may differ depending on the species and prey availability. This is the first monitoring study to explain syngnathid abundances and dietary regimes within macroalgal beds in Cíes Archipelago (Atlantic Islands Marine National Park, North West Iberian Peninsula). We sampled the epifaunal assemblages in seaweed communities dominated by the canopy-forming macroalgae Gongolaria baccata and Codium spp. seasonally during 2 years. The epifaunal structure was mostly represented by harpacticoid copepods, amphipods (especially gammarids) and gastropods. Epifauna exhibited low plant-host specificity and a higher dominance of amphipods on the more structurally complex macroalgae G. baccata. The epifaunal assemblages and syngnathid specimens were assessed for trophic structure using stable isotopes (δ13C and δ15N). The three syngnathids (Hippocampus guttulatus, Syngnathus acus, and Entelurus aequoreus) inhabiting Cíes Archipelago were sympatric. They occupied highly similar trophic positions (TPs), but differed in niche size, in such a way that the snake pipefish E. aequoreus would likely feed on smaller prey. The assessment of the feeding regime in the dominant great pipefish S. acus revealed that amphipods mostly contributed to bulk diet, followed by isopods, carideans, and copepods, whereas mysidaceans were not highly consumed. Seasonal changes in both epifaunal structure and syngnathids abundance confirmed that syngnathids are seasonal residents in Cíes Archipelago, migrating to other areas in autumn when the seaweed cover is drastically reduced and the epifaunal structure modified. This study showed the importance of Gongolaria assemblages in Cíes Archipelago, providing rich dietary sources and potentially contributing to higher abundances and diversity of syngnathids. Ongoing cover reduction in Gongolaria assemblages in certain regions (e.g., Mediterranean) should be considered a potential ecological concern for syngnathids and accompanying fauna, requiring further investigations.This study was financially supported by the Spanish Government with project Hippoparques (Ref. 1541S/2015, Organismo Autónomo de Parques Nacionales de España, Ministerio para la Transición Ecológica y Reto Demográfico, MITECO, Spain

Assessing the Importance of Kelp Forests for Small-Scale Fisheries Under a Global Change Scenario

[Abstract] Kelp forests are critical habitats for temperate coasts that are experiencing dramatic declines worldwide in recent decades. Yet, even though they often support wildlife populations of high socioeconomic value, the consequences of kelp forest decline for small-scale fisheries (SSFs) have received surprisingly little attention. Here, we take the first step to fill this gap through the local ecological knowledge (LEK) of SSF fishers whose fisheries are associated with this habitat in NW Spain. LEK was used to 1) estimate kelp forest loss, 2) identify the main fisheries associated with kelp forests, 3) gain insight into the changes these fisheries may have undergone in recent times, 4) evaluate the economic importance of kelp in the study area, and 5) describe the commercial chain of exploited kelps and relevant fisheries related to them. Fisher’s knowledge of kelp forests was documented through interviews with the help of a semi-structured questionnaire with open–closed questions about the small-scale fishery and its target species. Additionally, participants were asked to map the current and former (20 years ago) distribution of kelp forests in their fishing area. Results show that a range of fish, crustaceans, mollusks, echinoderms, and even the kelp itself are fished/harvested in the study area, suggesting the socioeconomic value of those species. The most intensively targeted species usually belong to fisheries with high commercial value, and first-sale data indicate that they are worth some 10 million euros to the local economy. On the other hand, compared to two decades ago, fishers reported a substantial contraction in the area occupied by kelp forests and decreases in the fisheries typically associated with this habitat. Landing data partly support this perception of a decline in catches. Altogether, this information will be useful to foster kelp forest conservation and to evaluate their socioecological and economic implications for SSFs.This research was funded by the “Fundación Biodiversidad y el Ministerio de Transición Ecológica y el Reto Demográfico.” BioCost Research Group acknowledges funding from Xunta de Galicia (grants ED431D 2017/2020 and ED431B 2018/49 of “Axudas para a consolidación e estructuración de unidades de investigación competitivas do SUG” program). CP-C received financial support from Xunta de Galicia “Axudas de apoio á etapa de formación posdoutoral “(grant ED481B-2021/095)”. SB received financial support from the Xunta de Galicia and the European Union (European Social Found – ESF) (grant ED481A2018/101). This publication has been funded by the University of la Laguna though the Vicerrectorado de Investigación, Transferencia y Campus Santa Cruz y SurXunta de Galicia; ED431D 2017/2020Xunta de Galicia; ED431B 2018/49Xunta de Galicia; ED481B-2021/095Xunta de Galicia; ED481A2018/10

Understanding the Local Drivers of Beta-Diversity Patterns Under Climate Change: The Case of Seaweed Communities in Galicia, North West of the Iberian Peninsula

[Abstract] Aim: To understand spatial-temporal changes (beta-diversity) in coastal communities and their drivers in the context of climate change. Coastal ecosystems are extremely exposed and dynamic, where changes in seaweed assemblages have been associated with changing water temperatures. However, at local scale, the effects of changes in the upwelling events and related stressors seek further exploration. Location: Galicia rías, North West of the Iberian Peninsula. Methods: Using data collected in 42 sampling localities in Galicia rias and over two time periods (1998 and 2014), we analysed changes in the seaweed community's composition through time and space. We calculated the temporal beta-diversity index and spatial beta-diversity as the pairwise composition differences between sampling localities. We use generalized dissimilarity models, to identify local environmental drivers of spatial and temporal beta-diversity. Results: We found a significant change in seaweed communities of Galicia rias, between 1998 and 2014 (temporal beta-diversity). They were mostly related to species loss rather than to species replacement. The dissimilarity among localities (spatial beta-diversity) was significantly higher in 2014 than in 1998. Nitrate concentration was consistently predicted as the main driver of both temporal and spatial beta-diversity patterns. Main conclusions: Unlike other studies in marine ecosystems, our results suggest that observed changes in the structure of perennial seaweed assemblages in Galicia Rias might lead to a local biotic heterogenization, indirectly linked to climate change through changes in nutrients availability and the upwelling intensity. Changes in Galicia seaweed communities call scientific attention to the importance of local stressors in climate change studies.Portugal. Fundação para a Ciência e a Tecnologia; PTDC/BIA-BMA/31893/201

Species composition, distribution, and zonation patterns in the intertidal seaweed assemblages from Santo Antão, Cape Verde

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Intertidal communities have been extensively studied for decades. Many of these studies have focused on macroalgae, as they are key components of many rocky coastal ecosystems. Despite this, there are still regions of the world where there is a lack of knowledge of intertidal macroalgal communities. This is the case in some tropical regions, such as the Cape Verde archipelago, located on the tropical west coast of Africa. To contribute to the knowledge of the macroalgal communities of this region, during July 2022, we studied the distributional pattern and zonation of macroalgal communities along the rocky intertidal of Santo Antão Island, the northernmost island of the archipelago and the least studied. Using a nested design, we compared the macroalgal assemblages of six rocky shores along the entire coastline, including three sites per shore, and four quadrats per site and tidal level. We found 43 macroalgal species – 29 Rhodophyta, 12 Ochrophyta, 2 Chlorophyta – and one Cyanobacteria. The orders Ceramiales, Corallinales, and Gigartinales were the groups more represented, followed by Ectocarpales and Dictyotales. The upper intertidal was dominated by brown algae, while red algae dominated the middle intertidal. Green algae had a scarce presence in both tidal levels. Our results found no differences between the north and south of the island but between rocky shores and tidal levels. Our results provide for the first time comprehensive information on the seaweed community structure, zonation patterns, and a comparison of seaweed abundances in a vertical and horizontal gradient along the entire rocky shores of Santo Antão Island. In the face of the current climate change, our data can be the baseline for future work on algal communities in this región.Xunta de Galicia; ED481B-2021/095This research was funded by Fundação para a Ciência e a Tecnologia (FCT), Portugal (DivRestore/0006/2020) through the 2020–2021 Biodiversa and Water JPI joint call for research projects, under the BiodivRestore ERA-NET Co-fund, Portugal (GA N◦101003777). MD was supported by a CEEC contract (CEECINST/00027/2021) funded by FCT, Portugal, and MD, FA, and CV were partly funded by UIDB/04423/2020 and UIDP/04423/2020, all through Portuguese national funds, Portugal. CP-C received financial support from Xunta de Galicia ‘‘Axudas de apoio á etapa de formación posdoutoral, ‘‘ Spain (grant ED481B-2021/095)’’. Funding for open access charge by Universidade da Coruña/CISUG

Small but strong: Socioeconomic and ecological resilience of a small European fishing community affected by a submarine volcanic eruption

[Abstract] Small-scale coastal fishing communities are facing many new challenges, such as rapid ecological changes created by anthropogenic and natural events like earthquakes or volcanic eruptions. This paper explores how a coastal population has responded to such an event and highlights the diverse coping strategies used to tackle it. This research was conducted on the island of El Hierro (Spain), where a submarine volcanic eruption occurred in 2011, affecting a multiple-use Marine Protected Area (MPA) and the nearby fishing community of La Restinga. Our study illustrates how the local population coped with this situation by combining multiple monetary and non-monetary activities (e.g., informal exchanges) as well as the role of institutions in increasing local resilience by supporting fishers' demands and allowing their participation in the decision-making process in the immediate wake of a catastrophic event. Local families also exploited various natural resources in and near the MPA, thus ensuring access to crucial marine resources and continued recreational/cultural services. The results suggest that collective action played a key role in the recovery process after the eruption, creating some advantages for different local groups despite the hazardous nature of the event.This was supported by the Cajacanarias Foundation and Fundación Bancaria “La Caixa'' [grant number 2017REC23], and the Ramón Areces Foundation through the XVII Call for Social Research Grant [grant number CISP17A5887]. Some specific research activities were also supported by the INTURMAR project supported by the ‘Smart Specialization Strategy of the Canary Islands RIS-3 co-financed by the Operational Program FEDER Canarias 2014–2020’ [grant number ProID2017010128]. RCM, JPF, JAG and AST would also like to acknowledge the Macarofood project (Interreg-MAC/2.3d/015), with the support of the European Regional Development Fund. CPC and RBL received funding from Xunta de Galicia (Axudas para a consolidación e estruturación de unidades de investigación competitivas do SUG, grants ED431D 2017/20, ED431B 2018/49). CPC received financial support from Xunta de Galicia “Axudas de apoio á etapa de formación posdoutoral” (grant ED481B-2021/095). We acknowledge the collaboration of the Network of Marine Reserves of the General Secretary of Fisheries, Ministry of Agriculture, Food and Environment of Spain, as well as the participation of several families and small-scale fishers from La Restinga in this study. We also thank Inés Chinea-Mederos, Jeramin Herra and Alejandro Rodríguez-Pais for their collaboration during the fieldwork and data voids, also Eilyn Pérez-Amores and Nemesio Pérez in preparing some figuresFundación CajaCanarias; 2017REC23Fundación Bancaria "la Caixa"; 2017REC23Fundación Ramón Areces; CISP17A5887Xunta de Galicia; ED431D 2017/20Xunta de Galicia; ED431B 2018/49Xunta de Galicia; ED481B-2021/09

Adiciones florísticas y aportaciones corológicas para la flora bentónica marina del Atlántico ibérico.

New records and geographical additions to the benthic marine flora of the Atlantic Iberian PeninsulaPalabras clave. Atlántico Península Ibérica, distribución, macroalgas marinas, nuevas citas.Key words. Atlantic Iberian Peninsula, geographical distribution, new records, seaweeds