Light Stress Responses by the Eelgrass, Zostera marina (L)

Zostera marina is the dominant seagrass species in the Northern Hemisphere where it grows in sheltered bays and estuaries. As a consequence of its distribution its conservation is commonly threatened by poor coastal water quality. The high minimum light requirements of seagrasses results in water quality degradation (high turbidity and eutrophication) being a significant risk. Bioindicators of light stress can be used to interpret seagrass responses to light limitation and therefore act as sentinels for conservation management. However, there exists limited experimental inter-comparison of the effectiveness of multiple individual bioindicator responses. Meta-analysis suggests that rhizome sugars, shoot C:N, shoot growth, and number of leaves per shoot provide the most consistent response variables to increasing light limitation in seagrass, but this premise remains largely untested at the plant level as a direct comparison of multiple bioindicators. The present study aimed to test the morphological, physiological, and photo-physiological bioindicator responses of Z. marina to light stress applied within controlled laboratory conditions. These bioindicators were used to assign minimum light thresholds. Growth rate and photophysiological parameters (alpha, Ek, and ETRmax) were rapidly (1st week) and drastically affected by low light shade treatments (20.12 μmol photons m−2s−1 and lower). After 3 weeks at low light, significant reductions in maximum leaf length and leaf width were observed. Principal Component Analysis identified leaf length, shoot growth, shoot surface area, ETRmax, Ek, and alpha as having the strongest responses to reduced light. Shoot growth, ETRmax, Ek, and alpha were found to provide the best early warning of light limitation after 5–8 days. These results provide evidence for bioindicators of light stress in Z. marina and highlights the importance of understanding these responses for the successful management and conservation of this species

The ecology and demography of the introduced macroalga Undaria pinnatifida (Harvey) Suringar in Port Phillip Bay, Victoria, Australia

Information from this thesis provides a critical understanding of the environmental factors that influence the growth and reproduction of different life stages of Undaria pinnatifida in Port Phillip Bay. Such information is important towards understanding the potential spread of this invasive species and may provide insight into methods that can be used to limit its expansion in southern Australian waters. In 1996 Undaria pinnatifida (Harvey) Suringar (Laminariales: Phaeophyta) was found growing in coastal waters of Port Phillip Bay, Victoria, Australia. Undaria pinnatifida is an opportunistic colonizer capable of high rates of reproduction and fast growth rates producing high density populations. It is the dominant macroalgal species at the site of invasion during winter and spring and has the potential for further spread from its current distribution in the northern part of Port Phillip Bay. This is the first in Australia examining the effects of temperature, nitrogen concentration, photon flux density and photoperiod on germination of zoospores, gametophyte growth and reproduction of U. pinnatifida in culture. Information on its recruitment, growth and reproductive capacity in the field is also presented for the first time for a population Australia

Response to the Proposal for a Directive on Corporate Sustainability Due Diligence by Nordic and Baltic Company Law Scholars

On February 23, 2022, The EU Commission published its Proposal for a Directive of the European Parliament and of the Council on Corporate Sustainability Due Diligence and amending Directive (EU) 2019/1937 (“CSDDD” or “the Proposal”). The purpose of the Proposal, to further the “Union’s transition to a climate-neutral and green economy in line with the European Green Deal and in delivering on the UN Sustainable Development Goals”, is of great importance, and the Commission’s initiative is therefore commendable. However, it is our firm opinion that the Proposal should not be enacted in its present form, and that if it were to be, it would not only damage European businesses but also run the risk of having an adverse effect on both the transition to a climate-neutral economy as well as the goal of delivering on the UN Sustainable Development Goals. This is to a large extent because many of the Proposal’s provisions are excessive, unfounded and disproportionate and as such in violation of the fundamental principles of subsidiarity and proportionality safeguarded by Art. 5 TEU as well as having a questionable basis in Art. 50 TFEU. Furthermore and in regard of procedure, we find that the presentation of the Proposal by the Commission represents a disregard for the principles of better regulation that should not pass unnoticed and must be observed in the future to maintain trust in the legislative process of the Union.In this response to the consultation, we have presented an analysis of the key issues of the Proposal from a corporate governance perspective. We have divided the response into two parts: one on the pure corporate governance parts of the Proposal (article 15, 25 and 26) and one of the due diligence parts of the Proposal. With regards to the corporate governance parts of the Proposal, our conclusion is that they, by and large, should not be included in the proposed directive at all. Including them would in several ways be in breach of the EU principles on subsidiarity and proportionality, but perhaps more importantly, they are not only unsubstantiated by available empirical evidence on corporate behaviour, but also refuted by what we know. There is also good reason to believe that the proposed rules on director’s duties and environmental remuneration would risk decreasing the effectiveness of the stock markets within the EU contrary to the goal of a Capital Market Union, which also risk slowing down the necessary transition to a green economy and the goals of the EU Green Deal. The regulation necessary for the Capital Market Union and the EU Green Deal should complement each other, not collide as would be the outcome if the Proposal is adopted in its present form.With regards to the due diligence parts of the Proposal, our criticism is limited to corporate governance aspects and far less fundamental. We primarily believe that grounds for harmonisation needs further consideration in the present very challenging times, that Article 22 on Civil Liability might in several ways be counter-productive to the goals of the Proposal, that the effects on SMEs as well as for the financial companies included covered by the Proposal warrants further analysis, that the choice to focus the Proposal on individual companies instead of company groups needs to be reviewed, and that a risk based approach should be taken rather than an approach were companies are unable to focus their efforts to where they can be most effective. Overall, these issues can be worked out, but if they are not, then the proposed directive would not only have a severe adverse impact on EU companies and possibly capital markets, but might actually hinder EU companies from acting in the way that the Proposal aims for them to do.This joint response to the public consultation is made by a group of Nordic and Baltic company law scholars who, although we may not agree on every detail, do share the main arguments and grave concerns expressed here

Chlorophyll fluorescence measures of seagrasses Halophila ovalis and Zostera capricorni reveal differences in response to experimental shading

In coastal waters and estuaries, seagrass meadows are often subject to light deprivation over short time scales (days to weeks) in response to increased turbidity from anthropogenic disturbances. Seagrasses may exhibit negative physiological responses to light deprivation and suffer stress, or tolerate such stresses through photo-adaptation of physiological processes allowing more efficient use of low light. Pulse Amplitude Modulated (PAM) fluorometery has been used to rapidly assess changes in photosynthetic responses along in situ gradients in light. In this study, however, light is experimentally manipulated in the field to examine the photosynthesis of Halophila ovalis and Zostera capricorni. We aimed to evaluate the tolerance of these seagrasses to short-term light reductions. The seagrasses were subject to four light treatments, 0, 5, 60, and 90% shading, for a period of 14 days. In both species, as shading increased the photosynthetic variables significantly (P < 0.05) decreased by up to 40% for maximum electron transport rates (ETRmax) and 70% for saturating irradiances (Ek). Photosynthetic efficiencies (α) and effective quantum yields (ΔF/Fm′) increased significantly (P < 0.05), in both species, for 90% shaded plants compared with 0% shaded plants. H. ovalis was more sensitive to 90% shading than Z. capricorni, showing greater reductions in ETRmax, indicative of a reduced photosynthetic capacity. An increase in Ek, Fm′ and ΔF/Fm′ for H. ovalis and Z. capricorni under 90% shading suggested an increase in photochemical efficiency and a more efficient use of low-photon flux, consistent with photo-acclimation to shading. Similar responses were found along a depth gradient from 0 to10 m, where depth related changes in ETRmax and Ek in H. ovalis implied a strong difference of irradiance history between depths of 0 and 5–10 m. The results suggest that H. ovalis is more vulnerable to light deprivation than Z. capricorni and that H. ovalis, at depths of 5–10 m, would be more vulnerable to light deprivation than intertidal populations. Both species showed a strong degree of photo-adaptation to light manipulation that may enable them to tolerate and adapt to short-term reductions in light. These consistent responses to changes in light suggest that photosynthetic variables can be used to rapidly assess the status of seagrasses when subjected to sudden and prolonged periods of reduced light