Complexity Of Marine Ecosystems Research Articles

Multi-Factors Synthetically Contribute to Ulva prolifera Outbreaks in the South Yellow Sea of China

In recent years, the frequent outbreaks of Ulva prolifera in the South Yellow Sea have become the largest-scale green tide disasters in the world. The causes of its outbreaks have garnered widespread attention, particularly the coupled effects of multiple factors. Leveraging the Google Earth Engine (GEE) platform, this study conducted a long-term investigation of the Yellow Sea green tide disaster and the factors using multi-source satellite imagery. Finally, the combined effects of natural environmental changes and human activities on Ulva prolifera were analyzed by redundancy analysis (RDA) and variation partitioning analysis (VPA). The results indicate: (1) Since 2018, the scale of Ulva prolifera in the South Yellow Sea has shown a distinct “biennial” trend. (2) Regarding environmental factors, SST, PAR, precipitation, and windspeed have certain effects on the growth of Ulva prolifera. However, they cannot be considered as determining factors for the outbreak of Ulva prolifera (0.002 < R2 < 0.14). Regarding anthropogenic factors, the recycle time of Pyropia yezoensis culture rafts has a relatively minor influence on the extent of Ulva prolifera. There exists a certain positive correlation (R2 = 0.45) between the human footprint index (HFI) of Jiangsu Province and the annual variation in Ulva prolifera area in the South Yellow Sea. (3) The combined effects of multiple factors influence green tide outbreaks. The Ulvatotal explanatory power of SST, PAR, precipitation, windspeed, HFI, and the recycle time of Pyropia yezoensis culture rafts for the annual variation in the Ulva prolifera area is 31.8%, with these factors interweaving and mutually influencing each other. This study offers important insights into quantifying the driving forces behind Ulva prolifera in the South Yellow Sea, providing valuable information for a deeper comprehension of the complexity of marine ecosystems and sustainable management.

Sustainable fisheries: Towards operationalization of decision making accounting for biodiversity

Overexploitation of biotic resources constitutes a major threat on marine biodiversity while demand for seafood will rise in the next decades. Application of Life Cycle Assessment to marine ecosystems needs further focus. This study applies two existing methods (Langlois et al., 2014 and Emanuelsson et al., 2014) of fishing impact assessment on biodiversity to 125 common fish stocks fished in the 14 marine areas drawn by FAO and proposes operational guidelines for sustainable production and efficient conservation policies. We show that unsustainable fishing is responsible for a loss of up to 30 times the potential yield of major fish stocks such as Atlantic cod, red snapper and bluefin tuna. We identify depleted fish stocks for which biomass is up to 15 times lower than it should be (yellownose skate fished in South America) and stocks facing fishing mortality up to 1.9 × 107 times higher than required to allow sustainable recovery (Pacific Ocean perch fished on the US West Coast). Regarding intrinsic biodiversity, our study shows that we are not able to understand the consequences of overfishing through a cause-effect chain due to lack of science knowledge. However, we display how to limit the impacts on biodiversity by using complementary indicators at species and ecosystem level. The complexity of marine ecosystems and the remaining limits of studied methods are discussed, showing the compelling need for further data collection and analysis, and opening ways for targeted research.

Another Decade of Marine Climate Change Experiments: Trends, Progress and Knowledge Gaps

Anthropogenic climate change is a significant driver of change in marine ecosystems globally. To improve mechanistic understanding of the impact of climate-related stressors, experimental work on marine organisms has intensified in recent decades. A previous synthesis paper published nearly a decade ago established that Marine Climate Change Experiments (MCCEs) published from 2000–2009 were primarily laboratory-based and focused on single stressors and individual focal temperate species. Using consistent methodology, we compared the 2000–2009 analysis to experiments published in the following decade (i.e. 2010–2019) to assess recent trends in MCCEs and to determine to what extent knowledge gaps and research priorities have been addressed. The search returned 854 papers, vs. 110 from the 2000s, indicating considerable intensification of research effort and output. We found again that single species studies were most common, particularly with benthic invertebrates as model organisms, and that laboratory-based research comprised over 90% of all studies. However, multiple stressor experiments increased substantially, where tests for interaction effects between ocean acidification (i.e., increased pCO2) and warming were particularly common. Furthermore, a wider range of model species were studied and more community-level experiments were conducted in the 2010s compared with the 2000s. In addition, studies on behavioral responses, transgenerational effects, genetic adaptation and extreme climatic events increased markedly. These recent advances in MCCEs have undoubtedly improved understanding of how climate change will affect marine organisms and the communities and ecosystems they underpin. Going forward, biases in the type and distribution of model organisms should be addressed to enhance general understanding of responses to environmental change. Similarly, experiments should manipulate a greater number and range of climate and non-climate factors and increase the number of target organisms to increase realism. Finally, where possible, further research should be combined and contextualized with field-based experiments and observations to better reflect the complexity of marine ecosystems and yield more representative responses to ocean climate change.

Sclerobionts associated with Orbiramus from the Early Ordovician of Hubei, China, the oldest known trepostome bryozoan

In addition to a marked rise in marine biodiversity, the Ordovician witnessed the most profound increase in the complexity of marine ecosystems in the history of the earth, including the expansion of tiering and enhanced biotic interactions. In order to understand these changes, it is important to study palaeoecological relationships among organisms at the commencement of the Great Ordovician Biodiversification Event (GOBE). Here, we describe sclerobionts associated with one of the earliest bryozoans in the fossil record, the oldest known trepostome, Orbiramus from the Fenhsiang Formation (late Tremadocian) of Hubei Province, China. These sclerobionts are diverse and include borings (e.g. Trypanites and Sanctum), bioclaustrations of vermiform organisms, and syn-vivo fouling by the putative black coral Sinopathes and other bryozoans. Diverse sclerobiotic associations and intricate palaeoecological relationships had already been established between bryozoans and other metazoans by the Tremadocian, showing the early onset of the ‘hard substrate revolution’ during the GOBE.

Managing complexity of marine ecosystems: From the monitoring breakdown structure (MBS) to the baseline assessment. Trace metal concentrations in biomonitors of the Beagle Channel, Patagonia (2005–2012)

Abstract In this study we propose a conceptual framework, i.e. the Monitoring Breakdown Structure (MBS) as a tool for the management of marine ecosystems. The conceptual framework thinks through the complexity of marine ecosystems keeping into account the variety (space) and variability (time) dimensions. Consistently with the MBS we have built the control charts of trace metal concentrations of two selected biomonitors in the Beagle Channel (south Patagonia) (case study). Thus, we have tested the aptitude of two species of mollusks as biomonitors of heavy metal (HMs) pollution. The selected species were the limpet Nacella (P) magellanica and the bivalve Mytilus chilensis. Seven hundred eighty-five samples were collected along 170 km of the coastal area of the Beagle Channel (BC), (Tierra del Fuego, Argentina) in seven selected georeferenced locations and four sampling campaigns (2005, 2007, 2011, 2012). Cd, Cr, Cu, Ni, Pb and Zn determinations in seawater and mollusks by atomic absorption spectrometry (AAS) were carried out. The calculation of the respective concentration factors (CFs), i.e. their capacity as strong bioaccumulators, was also conducted. This is of relevance because it aims to use these data as a baseline reference for other geographical areas. Second, we have compared metal bioaccumulation differences among sites and the contamination trend by building, for the first time, the control charts of the baseline metal concentrations in the biomonitors. For these purposes, we applied probabilistic Johnson's method. Furthermore, the control charts (based on four years baseline data) allowed us to test the contamination trend by plotting data from 2012 vs 2011. Our results confirm N. magellanica as an extremely strong accumulator of Cd, and M chilensis strong bioaccumulator of Cd and Zn. Zn was the most abundant metal followed by Cu. Overall, regarding the contamination trend, based on thousands of determinations we observed that the six mean metal levels were quite constant over time. Moreover, metal distribution among sites turned out to be not univocal (no one site is more contaminated than the other sites). Thus, the expected hypothesis of Ushuaia Harbour as being the most contaminated site should be reconsidered. This reinforces the hypothesis of our data as baseline data (except for cadmium), that should be considered in management decisions about future environmental monitoring programs, i.e. preventing/managing marine accidents.

Balancing yield with resilience and conservation objectives in harvested predator–prey communities

The global overexploitation of fish stocks is endangering many marine food webs. Scientists and managers now call for an ecosystem‐based fisheries management, able to take into account the complexity of marine ecosystems and the multiple ecosystem services they provide. By contrast, many fishery management plans only focus on maximizing the productivity of harvested stocks. Such practices are suggested to affect other ecosystem services, altering the integrity and resilience of natural communities. Here we show that while yield‐maximizing policies can allow for coexistence and resilience in predator–prey communities, they are not optimal in a multi‐objective context. We find that although total prey and predator maximum yields are higher with a prey‐oriented harvest, focusing on the predator improves species coexistence. Also, moderate harvesting of the predator can enhance resilience. Furthermore, increasing maximum yields by changing catchabilities improves resilience in predator‐oriented systems, but reduces it in prey‐oriented systems. In a multi‐objective context, optimal harvesting strategies involve a general tradeoff between yield and resilience. Resilience‐maximizing strategies are however compatible with quite high yields, and should often be favored. Our results further suggest that balancing harvest between trophic levels is often best at maintaining simultaneously species coexistence, resilience and yield.

How can we identify and communicate the ecological value of deep-sea ecosystem services?

Submarine canyons are considered biodiversity hotspots which have been identified for their important roles in connecting the deep sea with shallower waters. To date, a huge gap exists between the high importance that scientists associate with deep-sea ecosystem services and the communication of this knowledge to decision makers and to the wider public, who remain largely ignorant of the importance of these services. The connectivity and complexity of marine ecosystems makes knowledge transfer very challenging, and new communication tools are necessary to increase understanding of ecological values beyond the science community. We show how the Ecosystem Principles Approach, a method that explains the importance of ocean processes via easily understandable ecological principles, might overcome this challenge for deep-sea ecosystem services. Scientists were asked to help develop a list of clear and concise ecosystem principles for the functioning of submarine canyons through a Delphi process to facilitate future transfers of ecological knowledge. These ecosystem principles describe ecosystem processes, link such processes to ecosystem services, and provide spatial and temporal information on the connectivity between deep and shallow waters. They also elucidate unique characteristics of submarine canyons. Our Ecosystem Principles Approach was successful in integrating ecological information into the ecosystem services assessment process. It therefore has a high potential to be the next step towards a wider implementation of ecological values in marine planning. We believe that successful communication of ecological knowledge is the key to a wider public support for ocean conservation, and that this endeavour has to be driven by scientists in their own interest as major deep-sea stakeholders.

Relative importance of fisheries, trophodynamic and environmental drivers in a series of marine ecosystems

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 459:169-184 (2012) - DOI: https://doi.org/10.3354/meps09805 Relative importance of fisheries, trophodynamic and environmental drivers in a series of marine ecosystems Caihong Fu1,*, Sarah Gaichas2, Jason S. Link3, Alida Bundy4, Jennifer L. Boldt1, Adam M. Cook4, Robert Gamble3, Kjell Rong Utne5, Hui Liu3, Kevin D. Friedland6 1Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, British Columbia V9T 6N7, Canada 2NOAA, National Marine Fisheries Service, Alaska Fisheries Science Center, Seattle, Washington 98115, USA 3NOAA, National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole, Massachusetts 02543, USA 4Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia B2Y 4A2, Canada 5Institute of Marine Research, Nordnesgt 33, 5085 Bergen, Norway 6NOAA, National Marine Fisheries Service, Northeast Fisheries Science Center, Narragansett, Rhode Island 02882, USA *Email: caihong.fu@dfo-mpo.gc.ca ABSTRACT: Marine ecosystems are influenced by drivers that operate and interact over multiple scales, resulting in nonlinear or abrupt responses to perturbation. Because of the inherent complexity of marine ecosystems, progress towards an understanding of factors that affect fisheries production will be most efficient if researchers adopt a comparative approach across ecosystems using suites of indicators. The goals of this study were to explore a suite of biomass- and catch-based ecosystem response indicators for 9 northern hemisphere ecosystems relative to indices that capture the influence of fisheries, trophodynamic and environmental drivers, and to compare the relative influence of the triad of drivers. Partial least squares regression was used to explore relationships between the ecosystem response indicators and predictor drivers and to estimate the relative importance of each of the triad of drivers. Across ecosystems we have identified a few common observations: (1) environmental drivers, particularly temperature-related independent variables, are most likely related to total system biomass and biomass of specific biological groups (e.g. gadoid or clupeid fishes); (2) trophodynamic drivers are most relevant to the mean trophic level of community and the demersal-to-pelagic biomass ratio; and (3) fisheries drivers tend to be related to the catch-based indicators, such as fishing-in-balance and percent of primary production required to support fisheries. Overall, each of the triad of drivers was important for all ecosystems; however, the relative importance of each driver and the indicators they most affected varied among ecosystems, suggesting that an examination of a suite of indicators and drivers is required. A key finding is that fishing is categorically an important driver, but to explain biomass trends it is very important to consider environmental drivers as well. KEY WORDS: Marine ecosystems · Ecosystem indicators · Partial least squares regression · Multiple drivers Full text in pdf format Supplementary material PreviousNextCite this article as: Fu C, Gaichas S, Link JS, Bundy A and others (2012) Relative importance of fisheries, trophodynamic and environmental drivers in a series of marine ecosystems. Mar Ecol Prog Ser 459:169-184. https://doi.org/10.3354/meps09805 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 459. Online publication date: July 12, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

A three-isotope approach to disentangling the diet of a generalist consumer: the yellow-legged gull in northwest Spain

The widespread omnivory of consumers and the trophic complexity of marine ecosystems make it difficult to infer the feeding ecology of species. The use of stable isotopic analysis plays a crucial role in elucidating trophic interactions. Here we analysed δ15N, δ13C and δ34S in chick feathers, and we used a Bayesian triple-isotope mixing model to reconstruct the diet of a generalist predator, the yellow-legged gull (Larus michahellis) that breeds in the coastal upwelling area off northwest mainland Spain. The mixing model indicated that although chicks from all colonies were fed with a high percentage of fish, there are geographical differences in their diets. While chicks from northern colonies consume higher percentages of earthworms, refuse constitutes a more important source in the diet of chicks from western colonies. The three-isotope mixing model revealed a heterogeneity in foraging habitats that would not have been apparent if only two stable isotopes had been analysed. Moreover, our work highlights the potential of adding δ34S for distinguishing not only between terrestrial and marine prey, but also between different marine species such as fish, crabs and mussels.

On the optimal path in the dynamic pool model for a fishery

Ecosystem-based fishery management (EBFM) is a new direction for fishery management, essentially reversing the order of management priorities to start with the ecosystem rather than the target species. This concept of management is a direct extension of the concept of a holistic approach incorporating interspecific interactions and physical environmental influences. However, because of the limited understanding of the complexity of marine ecosystems, few fisheries are actually managed on a multispecies basis. Even now, in order to specify a practical fishing policy we need a single-species model and utilize it by partially taking account of the effects of other factors mentioned above on the target species biomass. In fact, it is contended that in systems with moderate amounts of data, EBFM could be characterized by effective single-species management with the addition of precautionary set-asides for unknown ecosystem components. Hence, it is still necessary to examine a single-species model so as to clarify the extent of its applicability. The model investigated in this paper is what is called the dynamic pool model, which was proposed by C.W. Clark in the mid-1970s as a dynamic optimization of the classic Beverton and Holt static model for a fishery, in an attempt to make the process of growth and aging inherent in each of the creature resources reflect directly into the economic process. This dynamic model has been applied to a wide variety of commercial fish species. However, the applications have been largely confined to computer simulations using the discrete-time stand-by of the original Clark continuous-time model. This situation is caused mainly by the complexity of the mathematical structure of the Clark model. In this paper, we first specify the material related to the complexity. Subsequently, we provide a rigorous proof for the long-standing conjecture due to Clark concerning the optimal path or harvesting schedule. In addition, two derivative cases are examined: one is the case in which a year-class of fish leaves a given fishing sea area permanently before its natural biomass peaks, the other is the case in which the escapement of a year-class is required to be more than a given minimum level.