Search Results (8)

Coralligenous bioconstructions are a key Mediterranean ecosystem for their associated biodiversity and role in the blue carbon cycle. They are also sensitive to environmental alterations (e.g., climate change) and other anthropic impacts related to coastal anthropization (e.g., fishing activities). Marine-coastal zone protection, conservation programs and management strategies are essential to guarantee a good ecological status of the coralligenous habitat. In this context, environmental and ecosystem accounting are useful tools to measure natural capital stocks and ecosystem service flows associated with marine ecosystems, conveying their importance in scientific and policy contexts. Indeed, the importance of marine ecosystems is often overlooked due to the difficulty of expressing their value in common units, making it challenging for decision-makers to explore trade-offs between conservation and exploitation of marine ecosystems. In this study, a biophysical and trophodynamic environmental accounting model was used to assess the biophysical value of natural capital stocks of the coralligenous habitat in three Marine Protected Areas (MPAs) of the Campania Region (Southern Italy): Punta Campanella, Santa Maria di Castellabate, and Costa degli Infreschi e della Masseta. The natural capital value per unit area associated with the coralligenous habitat ranged from 2.44 × 10¹² to 4.72 × 10¹² sej m⁻² for Santa Maria di Castellabate and Punta Campanella, respectively. Despite the different intensive values of natural capital calculated for the MPAs, there were no significant differences both in the biomass values of the taxonomic groups and in the biomass-based Shannon diversity index. Additionally, the biophysical values were also converted into monetary units, with the aim of facilitating the understanding of the importance of natural stocks in socio-economic and political contexts. The economic equivalent of natural capital value refers to the total extent of the coralligenous habitat and ranged from about EUR 1 to 15 million for Costa degli Infreschi e della Masseta and Santa Maria di Castellabate, respectively. The results of this study could be useful for local managers and policy makers and may make them more likely to achieve biodiversity conservation and sustainable development goals in MPAs. This is the first study devoted to the assessment of natural capital value of coralligenous habitats. Future studies could complement the results of this study with biophysical and economic assessments of ecosystem service flows generated by coralligenous habitats, focusing on the role they play in human well-being. Full article

We used lipid, fatty acid, and stable isotope analyses to investigate variation, over nine months, in the trophodynamics of 10 dominant cryptofaunal, macroalgal/algal, and environmental components from two sites within a rhodolith (Lithothamnion glaciale) bed in southeastern Newfoundland (Canada). There was an overall shift from a diatom-based food web following the spring phytoplankton bloom to a kelp/algae-based food web during fall, accompanied by preferred use of EPA (20:5ω3) over DHA (22:6ω3) in most cryptofauna. The food web contained three trophic levels that encompassed: (1) direct feeding relationships from primary producers (e.g., rhodoliths, macroalgae) to second-order consumers (e.g., sea stars, polychaetes); (2) trophic subsidy from within and outside the rhodolith bed via settlement, resuspension, and consumption of macroalgal fragments and other detrital organic matter; and (3) strong pelagic/benthic coupling. Riverine input did not affect cryptofaunal diets, as shown by the lack of terrestrial biomarkers at the study site nearest to the riverine input, and there were minor differences in trophodynamics between both study sites. The present study’s findings, applicable to relatively broad spatial and temporal domains, as well as those of complementary studies of the same rhodolith bed, uncover high spatio-temporal stability of the rhodolith bed framework and of resident cryptofaunal abundance, diversity, and trophodynamics. Full article

Taiwan Bank (TB) is located in the southern Taiwan Strait (TS). The uplifted continental slope and bottom currents in this area result in the formation of upwelling areas, which serve as crucial fishing grounds. Climate-induced fluctuations in fish populations occur in the TS. However, how predation and competition affect the interspecies relationships in the TB ecosystem warrants clarification. In this study, we collected high-grid-resolution data on fishery activity (2013–2019) and constructed ecosystem models using Ecopath with Ecosim (EwE). Three mass-balanced models for determining the influence of El Niño–Southern Oscillation (ENSO) events on the TB ecosystem were constructed using EwE. A range of groups, including representative pelagic, benthic, and reef species, were collected for analyzing the relationship between migratory and sedentary species in terms of ecosystem structure variation due to climate change. The results demonstrated that the total system throughput (TST) was 10,556–11,122 t km⁻² year⁻¹, with an average transfer efficiency of 12.26%. According to the keystoneness index, calculated through mixed trophic impact analysis, Polydactylus sextarius and Scomber japonicus were the key species with top–down control and relatively high impact on the ecosystem in normal years. The keystone species also shifted to the predator fish Thunnus albacares and Katsuwonus pelamis during El Niño and La Niña events, respectively. Moreover, total biomass, TST, consumption, and respiration were noted to increase during ENSO events. However, during La Niña events, the diversity and connectance indexes were relatively low but pelagic species’ biomass was relatively high, whereas the biomass of most benthic and reef species was relatively high during El Niño events. Full article

Two cohorts of Atlantic bluefin tuna (Thunnus thynnus) larvae were sampled in 2017 and 2018 during the peak of spawning in the Gulf of Mexico (GOM). We examined environmental variables, daily growth, otolith biometry and stable isotopes and found that the GOM18 cohort grew at faster rates, with larger and wider otoliths. Inter and intra-population analyses (deficient vs. optimal growth groups) were carried out for pre- and post-flexion developmental stages to determine maternal and trophodynamic influences on larval growth variability based on larval isotopic signatures, trophic niche sizes and their overlaps. For the pre-flexion stages in both years, the optimal growth groups had significantly lower δ¹⁵N, implying a direct relationship between growth potential and maternal inheritance. Optimal growth groups and stages for both years showed lower C:N ratios, reflecting a greater energy investment in growth. The results of this study illustrate the interannual transgenerational trophic plasticity of a spawning stock and its linkages to growth potential of their offsprings in the GOM. Full article

Cryptobenthic fishes make up more than half of coral reef fish fauna and contribute greatly to coral reef trophodynamics and diversity. Because of their small size, they are easily overlooked and understudied. Some of them use corals as their habitat, but this association is not well understood. In the Caribbean, two common cryptobenthic gobies, Elacatinus evelynae and Coryphopterus lipernes, are usually observed residing on corals. In order to compare their habitat use, we investigated their distributions on a range of scleractinian host-coral species at three different depths (5, 10, and 15 m) at Curaçao, southern Caribbean. The numbers of both species were relatively low at 5 m. Furthermore, we investigated the relationship between fish size and depth and found that adult E. evelynae individuals were most common at 5 m depth and juveniles at 15 m depth. Novel host corals were found for both fish species. Taking host size into account, the gobies were most abundant on large coral colonies of two host species: E. evelynae on both Colpophyllia natans and Montastraea cavernosa, and C. lipernes only on C. natans. In summary, depth, host species, and host-colony size were found to be environmental factors that may determine the occurrence of both fish species. Full article

Charonia tritonis (Charoniidae), one of the largest marine gastropods and an echinoderm specialist, preys on Crown-of-Thorns starfish (CoTS), a recurring pest that continues to be a leading cause of coral mortality on Indo-Pacific reefs. Widespread historical exploitation has impacted their numbers, with standing populations considered rare throughout their habitat. Their life-stage attributes, i.e., teleplanic larvae, planktotrophic phase spanning years permitting transoceanic dispersal, and recruitment to coral reefs through oceanic influx with intense larval mortality, have likely hindered their recovery. Decline in numbers is hypothesised to account partially for periodic CoTS outbreaks, yet predator-prey dynamics between these two species that might influence this are poorly understood. The C. tritonis excretory secretome elicits a proximity deterrence effect on CoTS, the nature of which is under investigation as a possible tool in CoTS biocontrol scenarios. However, specificity and zone of impact in situ are unknown, and whether the mere presence of C. tritonis and/or predation pressure has any regulatory influence over CoTS populations remains to be established. The fundamental taxonomy and distinctive characteristics, biology and ecology of C. tritonis is summarized, and knowledge gaps relevant to understanding their role within coral reefs identified. Information is provided regarding exploitation of C. tritonis across its habitat, and prospects for conservation interventions, including captive rearing and stock enhancement to repopulate local regions, are discussed. Its predator-prey ecology is also examined and potential to mitigate CoTS considered. Recommendations to direct future research into this predator and for its inclusion in a CoTS integrated pest management strategy to improve coral reef health are offered. Full article

The Gulf of Aqaba (GoA), positioned between the Sinai Peninsula and the Saudi Arabian coast is characterized by its uniquely high saline, oligotrophic waters, and seasonally stratified hydrography. Despite its geographical significance, information on its zooplankton ecology and biodiversity is still meager. Hence, the present study was aimed to investigate the detailed diversity and ecology of the dominant carnivorous zooplankton taxon chaetognath in the pelagic waters of the GoA during summer. Despite the known water flow exchange between the GoA and the Red Sea, only five chaetognath species were observed in GoA which is markedly less than the number earlier recorded in the Red Sea, indicating the role of high saline water mass as an ecophysiological boundary for the inhabitance of many epipelagic chaetognaths. Euryhaline, Serratosagitta pacifica formed the dominant species in both the surface water and the upper 200 m water column and was observed to be the most suitable representative of this high saline environment. Conspicuous diel variability in the distribution of the different growth stages of chaetognaths in the surface waters can be attributed to their varied susceptibility to visually oriented predators. The positive relation observed in the abundance of chaetognaths and their main prey, copepods, and their carbon and nitrogen contents indicated their significance in the pelagic trophic ecology of the GoA. The present study, providing the ecology of a major zooplankton taxon of this unique basin will be relevant for understanding the ecology and trophodynamics of the zooplankton community of the GoA. Full article

Unprecedented recruitment of Gulf menhaden (Brevoortia patronus) followed the 2010 Deepwater Horizon blowout (DWH). The foregone consumption of Gulf menhaden, after their many predator species were killed by oiling, increased competition among menhaden for food, resulting in poor physiological conditions and low lipid content during 2011 and 2012. Menhaden sampled for length and weight measurements, beginning in 2011, exhibited the poorest condition around Barataria Bay, west of the Mississippi River, where recruitment of the 2010 year class was highest. Trophodynamic comparisons indicate that ~20% of net primary production flowed through Gulf menhaden prior to the DWH, increasing to ~38% in 2011 and ~27% in 2012, confirming the dominant role of Gulf menhaden in their food web. Hyperabundant Gulf menhaden likely suppressed populations of their zooplankton prey, suggesting a trophic cascade triggered by increased menhaden recruitment. Additionally, low-lipid menhaden likely became “junk food” for predators, further propagating adverse effects. We posit that food web analyses based on inappropriate spatial scales for dominant species, or solely on biomass, provide insufficient indication of the ecosystem consequences of oiling injury. Including such cascading and associated indirect effects in damage assessment models will enhance the ability to anticipate and estimate ecosystem damage from, and provide recovery guidance for, major oil spills. Full article