http://people.uncw.edu/pawlikj/2008AquatBotNagle.pdf

The habitat function of mangroves for terrestrial and marine fauna: a review

The mussel Mytilus californianus is a competitive dominant on wave—swept rocky intertidal shores. Mussel beds may exist as extensive monocultures; more often they are an everchanging mosaic of many species which inhabit wave—generated patches or gaps. This paper describes observations and experiments designed to measure the critical parameters of a model of patch birth and death, and to use the model to predict the spatial structure of mussel beds. Most measurements were made at Tatoosh Island, Washington, USA, from 1970—1979. Patch size ranged at birth from a single mussel to 38 m2; the distribution of patch sizes approximates the lognormal. Birth rates varied seasonally and regionally. At Tatoosh the rate of patch formation varied during six winters from 0.4—5.4% of the mussels removed per month. The disturbance regime during the summer and at two mainland sites was 5—10 times less. Annual disturbance patterns tended to be synchronous within 11 sites on one face of Tatoosh over a 10—yr interval, and over larger distances (16 km) along the coastline. The pattern was asynchronous, however, among four Tatoosh localities. Patch birth rate, and mean and maximum size at birth can be used as adequate indices of disturbance. Patch disappearance (death) occurs by three mechanisms. Very small patches disappear almost immediately due to a leaning response of the border mussels (0.2 cm/d). Intermediate—sized patches (<3.0 m2) are eventually obliterated by lateral movement of the peripheral mussels: estimates based on 94 experimental patches yield a mean shrinking rate of 0.05 cm/d from each of two principal dimensions. Depth of the adjacent mussel bed accounts for much of the local variation in closing rate. In very large patches, mussels must recruit as larvae from the plankton. Recovery begins at an average patch age of 26 mo; rate of space occupation, primarily due to individual growth, is 2.0—2.5%/mo. Winter birth rates suggest a mean turnover time (rotation period) for mussel beds varying from 8.1—34.7 yr, depending on the location. The minimal value is in close agreement with both observed and calculated minimal recovery times. Projections of total patch area, based on the model, are accurate to within 5% of the observed. Using a method for determining the age of patches, based on a growth curve of the barnacle Balanus cariosus, the model permits predictions of the age—size structure of the patch population. The model predicts with excellent resolution the distribution of patch area in relation to time since last disturbance. The most detailed models which include size structure within age categories are inconclusive due to small sample size. Predictions are food for large patches, the major determinants of environmental patterns, but cannot deal adequately with smaller patches because of stochastic effects. Colonization data are given in relation to patch age, size and intertidal position. We suggest that the reproductive season of certain long—lived, patch—dependent species is moulded by the disturbance regime. The necessary and vital connection between disturbance which generates spatial pattern and species richness in communities open to invasion is discussed.

Intertidal landscapes: disturbance and the dynamics of pattern [Mytilus californianus, mussels]

Vitamin C (L-ascorbic acid) has important antioxidant and metabolic functions in both plants and animals, but humans, and a few other animal species, have lost the capacity to synthesize it Plant-derived ascorbate is thus the major source of vitamin C in the human diet Although the biosynthetic pathway of L-ascorbic acid in animals is well understood, the plant pathway has remained unknown-one of the few primary plant metabolic pathways for which this is the case L-ascorbate is abundant in plants (found at concentrations of 1-5 mM in leaves and 25 mM in chloroplasts) and may have roles in photosynthesis and transmembrane electron transport We found that D-mannose and L-galactose are efficient precursors for ascorbate synthesis and are interconverted by GDP-D-mannose-3,5-epimerase We have identified an enzyme in pea and Arabidopsis thaliana, L-galactose dehydrogenase, that catalyses oxidation of L-galactose to L-galactono-1,4-lactone We propose an ascorbate biosynthesis pathway involving GDP-D-mannose, GDP-L-galactose, L-galactose and L-galactono-1,4-lactone, and have synthesized ascorbate from GDP-D-mannose by way of these intermediates in vitro The definition of this biosynthetic pathway should allow engineering of plants for increased ascorbate production, thus increasing their nutritional value and stress tolerance

The biosynthetic pathway of vitamin C in higher plants

We suggest that relatively few species attributes are of overriding importance to the structure of benthic marine algal communities and that these are often shared among taxonomically distant species. Data from the western North Atlantic, eastern North Pacific and Caribbean suggest that patterns in algal biomass, diversity and dominance are strikingly convergent when examined at a functional group level relative to the productivity and herbivore-induced disturbance potentials of the environment. We present a simple graphical model that provides a way to predict algal community composition based on these two environmental axes. This predictability stems from algal functional groups having characteristic rates of mass-specific productivity, thallus longevity and canopy height that cause them to «behave» in similar ways (...)

http://www.vliz.be/imisdocs/publications/131003.pdf

A functional group approach to the structure of algal-dominated communities

Organic carbon dynamics in mangrove ecosystems : a review

Article de synthese. Processus d'alimentation des animaux brouteurs; competition interspecifique et niche ecologique; budget energetique. Influence du broutage sur la repartition spatiale des algues et la structure des biocenoses intertidales. Adaptation des algues au broutage et coevolution des algues et des invertebres brouteurs

Grazing of intertidal algae by marine invertebrates

[Bei den Superfamilien der Brachyura, die weibliche Genitalporen am Sternum besitzen - Corystoidea, Oxystomata, Brachyrhyncha und Oxyrhyncha - wurde die Begattung studiert. Die mannlichen Tiere kopulieren nur mit vollig erhartetem Integument, wie es auch bei den Weibchen mancher Arten der Fall ist. Bei anderen Arten jedoch kopulieren die Weibchen gleich nach der Hautung, wenn die Schale also noch weich ist. Es gibt nun zwei grundsatzlich verschiedene Typen der Begattung. Typus I: Das Weibchen kopuliert gleich nach der Hautung, das Mannchen begleitet das Weibchen langere Zeit vor der Hautung und nach der Begattung; die Balz-Anreizungen sind hauptsachlich in chemischen Mitteln und in der Beruhrung konzentriert. Typus II: Das Weibchen kopuliert erst wenn die Schale erhartet ist, es gibt nur ein kurzes Liebesspiel und Gesicht- und Gehor-Anreizungen sind dabei am wichtigsten. Bei den Cancridae, Portunidae und Hymenosomatidae gibt es die Kopulation nach Typus I, bei den Xanthidae, Grapsidae und Ocypodidae hingegen hauptsachlich nach Typus II. Bei den Majidae kann die erste Kopulation nach Typus I vorgehen, die folgenden Begattungen verlaufen jedoch nach Typus II. Typus I der Begattung gibt es oft kombiniert mit der einfachen Form der Vagina: beide Merkmale werden jedoch als primitiv betrachtet und es ist unbewiesen, dass es hier funktionelle Zusammenhange gibt., Bei den Superfamilien der Brachyura, die weibliche Genitalporen am Sternum besitzen - Corystoidea, Oxystomata, Brachyrhyncha und Oxyrhyncha - wurde die Begattung studiert. Die mannlichen Tiere kopulieren nur mit vollig erhartetem Integument, wie es auch bei den Weibchen mancher Arten der Fall ist. Bei anderen Arten jedoch kopulieren die Weibchen gleich nach der Hautung, wenn die Schale also noch weich ist. Es gibt nun zwei grundsatzlich verschiedene Typen der Begattung. Typus I: Das Weibchen kopuliert gleich nach der Hautung, das Mannchen begleitet das Weibchen langere Zeit vor der Hautung und nach der Begattung; die Balz-Anreizungen sind hauptsachlich in chemischen Mitteln und in der Beruhrung konzentriert. Typus II: Das Weibchen kopuliert erst wenn die Schale erhartet ist, es gibt nur ein kurzes Liebesspiel und Gesicht- und Gehor-Anreizungen sind dabei am wichtigsten. Bei den Cancridae, Portunidae und Hymenosomatidae gibt es die Kopulation nach Typus I, bei den Xanthidae, Grapsidae und Ocypodidae hingegen hauptsachlich nach Typus II. Bei den Majidae kann die erste Kopulation nach Typus I vorgehen, die folgenden Begattungen verlaufen jedoch nach Typus II. Typus I der Begattung gibt es oft kombiniert mit der einfachen Form der Vagina: beide Merkmale werden jedoch als primitiv betrachtet und es ist unbewiesen, dass es hier funktionelle Zusammenhange gibt.]

Mating in the Brachyura

Relative growth in Crustacea is generally in accordance with the simple allometry rule, y = Bxα. The regulation of growth at each ecdysis is such as to result in the attainment, where possible, of the proportions dictated by this rule. Growth proceeds as a series of phases, each composed of from one to several instars. Within each phase there is simple allometric growth, but both the levels of allometry and the size of the variables often change at the transition between phases. These transition changes may be minimal, but they can be so prominent as to result in an obvious critical moult or metamorphosis. In Brachyura there is a consistent pattern of phases in the later post-larval life, the critical moults separating the final three phases being known as the pre-puberty and puberty moults respectively. There can be polymorphism of the terminal mature phase. The critical moults do not necessarily appear to have fixed positions in the sequence of post-larval instars.

https://www.jstor.org/stable/info/20103283

The determination of relative growth in crustacea

Developments during the past 20 years are reviewed for four aspects of crustacean growth. These are the hormonal control of moulting, the effects of external factors on growth rate, the patterns of growth and the determination of age. Hormonal control. The nature and structure of Moult Inhibiting Hormone has been determined, though the mechanism by which it inhibits crustecdysone production is still unclear. A role in moult control by Crustacean Hyperglycaemic Hormone has been demonstrated, but needs clarification. Methyl farnesoate, a juvenile hormone like substance, occurs in Crustacea: however, a clear function as a juvenile hormone has yet to be shown. External factors. The effect of increased temperature in reducing moult increments is supported by further data. Reduced food supply causes smaller moult increments and longer intermoult periods: the latter effect is generally proportionately greater. A role for CHH in this process is hypothesised. Patterns of growth. Little advance has occurred in understanding the rationale for the diversity of growth patterns. Computer modelling offers promise, but is constrained by lack of data on natural mortality for validation. Determination of age. The basic methods available remain size frequency analysis and tagging programmes. There have been advances in technology and methods of analysis, but no major breakthrough. Novel methods include radionuclide ratios (expensive, complex and give only duration of current intermoult), lipofuschin pigment assay (promising, but needs further validation), and annular structures in the infra-cerebral organ (still very speculative).

Growth in Crustacea — twenty years on

It is critical for our knowledge of biodiversity and ecosystem processes to understand how individual species contribute to ecosystem processes and how these contributions vary in space and time. We used a manipulative field experiment in five locations over 17° of latitude [from southern Portugal to the Isle of Man (British Isles)] to determine the relative response of rocky intertidal algal assemblages released from control by the grazing of limpets. Response ratios showed that when limpets were removed there was a trend of effects from north to south. In the north, grazing had a strong effect on algal assemblages, but removing grazers reduced spatial variability in assemblages. In the south, the effect of limpet grazing was far weaker and removal of grazers had a much reduced impact on spatial variability. Here we show a clear trophic control of an ecosystem in that grazing by limpets not only determines macroalgal abundance overall but also modifies ecosystem stability via variability in cover of algae.

Richard G. Hartnoll

Papers

Grazing of intertidal algae by marine invertebrates

Mating in the Brachyura

The determination of relative growth in crustacea

Growth in Crustacea — twenty years on

A continental scale evaluation of the role of limpet grazing on rocky shores