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a Abundance of microscopic sporophytes and b survival of macroscopic sporophytes (mean + SE, n = 6 and n = 6, respectively) for each experimental treatment at the end of the study. Different letters above bars indicate significantly different means according to SNK test
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Partitioning the effects of herbivory on different life stages of primary producers is key to understanding the population-wide consequences of herbivory. We assessed the performance of microscopic (MiS <1 mm) juveniles, macroscopic (MaS) juveniles and adult kelp (Laminaria ochroleuca) under contrasting herbivory regimes through a herbivore exclusi...
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Citations
... Consumption of microscopic kelp stages is another potential postsettlement issue (Henríquez et al., 2011;Zacher et al., 2016;Franco et al., 2017;Veenhof et al., 2022). Increased herbivory pressure on kelp sporophytes due to climate change has been considered a threat to kelp forests, either due to increased herbivory rates of native species or the arrival of tropical herbivores (Vergés et al., 2014;Franco et al., 2015;Fig. ...
Kelp forests are critical marine ecosystems that provide habitat and ecological services, as well as economic benefits. However, kelp forests worldwide are facing multiple pressures, including climate change and human activities. In this study, we investigated whether recruitment success, an infrequently recorded variable in kelp monitoring studies, was affected in degraded kelp reefs where adult golden kelps (Laminaria ochroleuca) were persistently absent due to fish consumption. We conducted a three-year seasonal monitoring of kelp recruits and juveniles in both healthy and degraded kelp reefs in northwest Spain. Our findings reveal a decline in spring kelp recruitment over time on degraded reefs, while it remained stable on healthy reefs. The results indicate that continued herbivory pressure can decrease kelp recruitment, suggesting the potential exhaustion of kelp stand resilience. Altogether, our study highlights the importance of biotic interactions, such as herbivory, in understanding changes in kelp forest dynamics. Moreover, it emphasizes the significance of including recruitment in kelp forest assessments as an indicator of resilience.
... Managers could combine these reserves and reintroductions with active restoration efforts for maximum chances of success, though it should be noted that there have been some instances where increased predator populations did not always result in kelp forest recovery (but in any case, can support their resilience) ). Similar solutions can also be applied to control the issue of grazing fish populations, which despite being a less common problem than sea urchin grazing, consistently occurs in areas such as southern California, eastern Japan, regions of Australia , Portugal (Franco et al. 2017) and Spain (Peteiro and Freire 2012). As sea temperatures rise, there will likely be an increase in the interaction between kelp and fish, meaning solutions will need to be explored further (Vergés et al. 2019). ...
... Managers could combine these reserves and reintroductions with active restoration efforts for maximum chances of success, though it should be noted that there have been some instances where increased predator populations did not always result in kelp forest recovery (but in any case, can support their resilience) ). Similar solutions can also be applied to control the issue of grazing fish populations, which despite being a less common problem than sea urchin grazing, consistently occurs in areas such as southern California, eastern Japan, regions of Australia , Portugal (Franco et al. 2017) and Spain (Peteiro and Freire 2012). As sea temperatures rise, there will likely be an increase in the interaction between kelp and fish, meaning solutions will need to be explored further (Vergés et al. 2019). ...
... Managers could combine these reserves and reintroductions with active restoration efforts for maximum chances of success, though it should be noted that there have been some instances where increased predator populations did not always result in kelp forest recovery (but in any case, can support their resilience) ). Similar solutions can also be applied to control the issue of grazing fish populations, which despite being a less common problem than sea urchin grazing, consistently occurs in areas such as southern California, eastern Japan, regions of Australia , Portugal (Franco et al. 2017) and Spain (Peteiro and Freire 2012). As sea temperatures rise, there will likely be an increase in the interaction between kelp and fish, meaning solutions will need to be explored further (Vergés et al. 2019). ...
Managing the harvesting of wild growing kelp is still
the most developed form of kelp management / Humans’ intensifying use of the ocean is exposing kelp to many pressures in addition to harvesting. The cumulative impacts of these pressures need to be addressed in an integrated manner / Ecosystem-based management is a strategic approach to integrated ecosystem management that
can act as an umbrella for other approaches, including marine spatial planning, MPAs and initiatives towards individual activities that affect kelp ecosystems / The management of kelp as ecosystems is usually
not specific and tends to be included in more general approaches to ocean management.
... Managers could combine these reserves and reintroductions with active restoration efforts for maximum chances of success, though it should be noted that there have been some instances where increased predator populations did not always result in kelp forest recovery (but in any case, can support their resilience) ). Similar solutions can also be applied to control the issue of grazing fish populations, which despite being a less common problem than sea urchin grazing, consistently occurs in areas such as southern California, eastern Japan, regions of Australia , Portugal (Franco et al. 2017) and Spain (Peteiro and Freire 2012). As sea temperatures rise, there will likely be an increase in the interaction between kelp and fish, meaning solutions will need to be explored further (Vergés et al. 2019). ...
Highlights
> There are no global law or policy instruments focused
explicitly on kelp, but kelp forests do benefit from
some international regimes.
> Many national laws and policies provide for the
protection, management, restoration and use of kelp,
although approaches vary in different jurisdictions.
> Awareness of the value and status of kelp forests is
growing, with further research needed to identify
ways to enhance laws and policies.
> Holistic governance is crucial to ensuring that
cumulative impacts are addressed, ecosystem
approaches are embedded and all stakeholders are
engaged.
... Managers could combine these reserves and reintroductions with active restoration efforts for maximum chances of success, though it should be noted that there have been some instances where increased predator populations did not always result in kelp forest recovery (but in any case, can support their resilience) ). Similar solutions can also be applied to control the issue of grazing fish populations, which despite being a less common problem than sea urchin grazing, consistently occurs in areas such as southern California, eastern Japan, regions of Australia , Portugal (Franco et al. 2017) and Spain (Peteiro and Freire 2012). As sea temperatures rise, there will likely be an increase in the interaction between kelp and fish, meaning solutions will need to be explored further (Vergés et al. 2019). ...
https://wedocs.unep.org/bitstream/handle/20.500.11822/42255/into_the_blue.pdf?sequence=3&isAllowed=y
... Managers could combine these reserves and reintroductions with active restoration efforts for maximum chances of success, though it should be noted that there have been some instances where increased predator populations did not always result in kelp forest recovery (but in any case, can support their resilience) ). Similar solutions can also be applied to control the issue of grazing fish populations, which despite being a less common problem than sea urchin grazing, consistently occurs in areas such as southern California, eastern Japan, regions of Australia , Portugal (Franco et al. 2017) and Spain (Peteiro and Freire 2012). As sea temperatures rise, there will likely be an increase in the interaction between kelp and fish, meaning solutions will need to be explored further (Vergés et al. 2019). ...
... Devido às suas Em Portugal, duas espécies perenes de kelp, nomeadamente Laminaria hyperborea e so, as populações atualmente persistentes em Portugal parecem ter uma longevidade mais baixa e menor capacidade reprodutiva em comparação com os registos históricos. Um recente estudo de monitorização da espécie realizado na região norte, mostrou uma diminuição de 12% da densidade de indivíduos em 10 anos (2011-2020)(191).As florestas de Cystoseira estão também entre os habitats mais importantes do Atlântico Norte. Em Portugal são encontradas várias espécies, tais como C. baccata, C. compressa, C. tamariscifolia e C. humilis, que são capazes de formar extensas canópias em ambientes rochosos intertidais e subtidais. ...
Este estudo responde ao desafio de refletir sobre política de biodiversidade no horizonte
2030, ponderando, em particular, aspetos relacionados com os binómios biodiversidade-
clima, -território, -águas interiores e costeiras, -oceano, e -pessoas. Estes cinco binómios representam, na realidade, uma teia de interações. A par das dimensões territoriais (terra, rios, albufeiras, mar), confluem dimensões temporais (alterações do clima e de dinâmicas socioeconómicas), componentes jurídicas e administrativas da política de conservação, em articulação com outras políticas sectoriais, e o financiamento público e privado que possa ser mobilizado no presente e no futuro. A partir de uma análise multidisciplinar faz-se um diagnóstico de tendências e vulnerabilidades e propõe-se uma agenda para alavancar técnica, administrativa e financeiramente a política de conservação e restauro da biodiversidade em Portugal continental e em território marinho sob jurisdição portuguesa, num contexto particularmente desafiante de alterações climáticas.
Pela primeira vez, em Portugal, e provavelmente noutros Estados congéneres, mobilizam-
-se e integram-se, num único exercício de diagnóstico, uma grande quantidade de dados
geográficos de biodiversidade em terra, águas interiores e no mar, com vista a gerar
cenários que possam suportar o processo de decisão política, proporcionando-se, ainda,
uma análise dos padrões e tendências da biodiversidade terrestre e marinha, tendo em
conta as mudanças climáticas projetadas para o país. Concomitantemente, analisam-se
documentos de política pública e procede-se a uma revisão seletiva de legislação.
O diagnóstico e reflexão que o acompanhou aponta para o que consideramos serem
os principais pontos fracos que condicionam a capacidade de o país alcançar as metas
da Estratégia Nacional de Conservação da Natureza e Biodiversidade 2030, à luz da
Estratégia Europeia de Biodiversidade 2030, designadamente:
| A dificuldade de acesso a dados centralizados e a limitada disponibilidade de
dados essenciais para a caracterização das tendências e vulnerabilidades da
biodiversidade, designadamente, no mar, no solo, em plantas e invertebrados;
| A ausência de consideração das ameaças decorrentes das alterações climáticas
e da perda de biodiversidade na planificação da conservação no território português
e nas políticas económicas e fiscais;
| A prevalência de uma gestão passiva face à gestão ativa da biodiversidade, que
limita a capacidade de empreender medidas de manutenção e restauro de populações
e ecossistemas;
| A fraca articulação intersectorial e interministerial, tanto em terra como no mar, que resulta
numa ineficiente e ineficaz (quando não perversa) utilização de fundos públicos;
| A escassa capacitação e empoderamento dos atores locais na gestão ativa do
capital natural, que limita a capacidade efetiva de intervenção no território;
| O subfinanciamento crónico das políticas públicas de conservação e o limitado
envolvimento do sector privado no financiamento da biodiversidade.
Neste contexto, indicam-se oportunidades para que o país possa aproveitar, consistentemente, a biodiversidade e os serviços dos ecossistemas a ela associados, como aliados na mitigação das alterações climáticas e propõe-se um pacote de medidas e políticas para reverter a tendência de degradação e perda do capital natural.
... Micrograzers (<2.5 mm) inhabiting algal turfs have been suggested as a potential factor contributing to the strong inhibitory effect turfs have on kelp recruitment (Dayton et al., 1984), yet there remains a paucity of experiential evidence for evaluating this hypothesis. While the impact of grazers on adult plants (Ling et al., 2015;Vergeś et al., 2016) and juvenile sporophytes (Sala and Dayton, 2011;Franco et al., 2017) can be severe, there remains a critical knowledge gap surrounding the effect of grazers on kelp gametophytes (Veenhof et al., 2022). ...
Kelp forests are economically important ecosystems that support a wealth of biodiversity but are declining globally. They are often replaced by biologically depauperate alternate stable states dominated by turfing algae. Hysteresis maintains algal turfs by inhibiting kelp recruitment, preventing the reestablishment of kelp forests. The mechanisms inhibiting kelp recruitment remain poorly understood as microscopic stages of kelp are difficult to study in situ. A potential mechanism contributing to the suppression of recruitment may be turf-facilitated grazing of kelp gametophytes, the haploid free-living reproductive life stage. Here we assess the resilience of kelp gametophytes to grazing pressure from a gastropod micrograzer commonly present in turf under current and future ocean warming scenarios. Gametophyte coverage and abundance were significantly reduced following grazing under all temperatures, however there was no significant effect of temperature on grazing rates. Once grazing pressure was removed, gametophyte abundance recovered to control levels, but the total coverage and length of gametophytes continued to decline in all treatments. Gametophytes were found to survive micrograzer ingestion and continued to grow in aggregations in the gastropod’s mucus trail and faeces, even producing sporophytes. Gametophyte survival post-ingestion may positively contribute to dispersal and sporophyte recruitment, however the lack of gametophyte recovery at elevated temperatures may counteract this effect under future ocean warming. Taken together, this study demonstrates complex interactions that take place in the turf micro-habitat of kelp gametophytes and highlights biotic factors influencing transitions between kelp forests and algal turfs.
... Macro-herbivore abundance was visually assessed seasonally between autumn 2019 and spring 2020 at the eight reefs. On each reef, all fish were counted along seven randomly oriented 25 × 4 m belt transects with the help of video recordings (Franco et al., 2017). Fishes were categorized according to trophic affinity (Rodríguez Solórzano et al., 1983;Miller and Loates, 1997;Muus et al., 1998;Froese and Pauly, 2019), and only seaweed-eating fish, both omnivorous and herbivorous, were considered for this study. ...
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.
