Reproductive strategies of marine benthic invertebrates revisited: facultative feeding by planktotrophic larvae

Fecundity-time models of reproductive strategies in marine invertebrates all predict that reproductive success is maximized only at the extreme levels of investment. Selection should drive egg sizes toward small eggs and planktotrophy or large eggs and lecithotrophy. The existence of two distinct larval types, feeding and nonfeeding, has been taken as confirmation of this prediction and has established the current paradigm for larval ecology. However, comparative and experimental evidence does not support the prediction that egg size is minimized in species with planktotrophic larvae. Recent discoveries have documented the existence of planktotrophs that have intermediate egg sizes, differing degrees of dependence on exogenous food, and differing capacities for facultative feeding. A fecundity-time model is presented that includes facultative larval feeding by dissociating the onset of feeding capability from the need for exogenous food. The facultative feeding model shows that reproductive success can be maximized at intermediate levels of investment per offspring between the minimum for development and the threshold for lecithotrophy, depending on the amount of food available to larvae and the intensity of planktonic mortality. A continuum of larval strategies is predicted.     

Distribution of South African marine benthic invertebrates applied to the selection of priority conservation areas

Available data on species distributions and endemicity were compiled and examined for 11 groups of South African marine invertebrates (2533 species). For five groups species richness adhered to a well‐documented pattern, increasing from west to east, but for the other groups species richness was highest along the south coast. Endemicity was generally highest along the south coast, and lowest along the east coast. The data base was then analysed using several types of complementarity analyses, each producing a minimum set of potential reserve areas, which cumulatively represent all invertebrate species analysed. Approaches based solely on rarity, species richness and endemicity demonstrated individual biases, suggesting a need to combine all three interests. Combining the three techniques produced similar results to the individual analyses, showing conservation priorities to be highest along the east coast. Specifically, the areas of Port Elizabeth and Durban were ranked high in all analyses. Consistently, a total of 16 sites was necessary to represent all species analysed. Comparisons with similar analyses on fish and seaweeds revealed similar findings. Existing invertebrate records were shown to be biased towards centres of high sampling activity, demonstrating a need of future sampling attention in under‐represented areas.     

Filling biodiversity gaps: benthic hydroids from the Bellingshausen Sea (Antarctica)

The Bellingshausen Sea constitutes the third largest sea in the Southern Ocean, though it is widely recognized as one of the less-studied Antarctic areas. To reduce this lack of knowledge, a survey to study the biodiversity of its marine benthic communities was carried out during the Bentart 2003 and Bentart 2006 Spanish Antarctic expeditions. The study of the hydroid collection has provided 27 species, belonging to ten families and 15 genera. Twenty-one out of the 27 species constitute new records for the Bellingshausen Sea, raising the total number of known species to 37, as also do nine out of the 15 genera. Candelabrum penola, Lafoea annulata, and Staurotheca juncea are recorded for the second time. Most species belong to Leptothecata. Sertulariidae with 13 species (48%) is by far the most speciose family, and Symplectoscyphus with seven species (26%), including S. bellingshauseni sp. nov. and S. hesperides sp. nov., the most diverse genus. Considering the whole benthic hydroid fauna of the Bellingshausen Sea, 18 species (69%) are endemic to Antarctic waters, either with a circum-Antarctic (12 species, 46%) or West Antarctic (6 species, 23%) distribution, 23 (88%) are restricted to Antarctic or Antarctic/sub-Antarctic waters, and only three species have a wider distribution. Bellingshausen Sea hydroid fauna is composed of a relatively high diversity of typical representatives of the Antarctic benthic hydroid fauna, though with a surprisingly low representation of some of the most diverse and widespread Antarctic genera (Oswaldella and Schizotricha), what could be related to the fact that its shelf-inhabiting hydroid fauna remains practically unknown.     

Red List of macrofaunal benthic invertebrates of the Wadden Sea

Parasites were observed in medium- and small-sized fish taken from the discards of a commercial shrimper during seven different cruises in the tidal channels of the North Frisian Wadden Sea (Süderaue, North Sea) from April to September 1991. In total, 442 fish comprising four species (Sprattus sprattus, Hyperoplus lanceolatus, Ammodytes tobianus, Pomatoschistus minutus) were investigated. The parasite fauna consisted of 22 species. The parasite community structure of the 4 hosts was compared. The diet of the hosts seemed to be the main factor determining the structure of the parasite community. Other factors could not be assessed. Eight species of parasites occurred as larval stages. This indicated that fish were intermediate or paratenic hosts in their life cycle. The nematodeHysterothylacium sp. (Anisakidae) and the digeneanCryptocotyle lingua (Heterophyidea) were the dominant parasites, reaching their highest prevalence and density in sprat and sand eel. Sprat and sand eel play a very important role in parasite transmission to predacious fish and seabirds.     

Abundance and distribution of invertebrate larvae in the Bellingshausen Sea (West Antarctica)

The central part of the Bellingshausen Sea has been poorly studied, partly because of the presence of ice during most of the year. The main aim of this study was to analyse the abundance and distribution of meroplankton, and the influence of oceanographic properties were investigated in the Bellingshausen Sea (West Antarctica) during the BENTART-06 cruise carried out in January–February 2006. Zooplankton samples were collected with a 80-μm mesh plankton net hauled vertically from a depth of 200?m to the surface at fifteen stations across the Bellingshausen Sea. Fifteen types of larval benthic invertebrates were found, with echinospira and nudibranch veligers being the most abundant. Hierarchical analysis and non-metric multidimensional scaling revealed a high degree of spatial variability in both larval abundance and larval types across the Bellingshausen Sea. The variability was significantly correlated with total chlorophyll-a and the contribution of large (>5?μm) phytoplankton to total chlorophyll, indicating the availability of food as an important factor determining the larval distribution observed. Nudibranch veligers, nemertean pilidia, echinoderm and planula larvae were more abundant at stations in the central Bellingshausen Sea, which was characterized by low phytoplankton biomass and production. Higher abundances of echinospira veligers and polychaete larvae were found at the more productive stations close to Peter I Island and the Antarctic Peninsula. The abundance and diversity of larval types found in the Bellingshausen Sea during the BENTART-06 cruise support the hypothesis that indirect development through larval swimming stages plays a key role in benthic recruitment in polar areas.     

Frequency of injury and the ecology of regeneration in marine benthic invertebrates

Many marine invertebrates are able to regenerate lost tissue following injury, but regeneration can come at a cost to individuals in terms of reproduction, behavior and physiological condition, and can have effects that reach beyond the individual to impact populations, communities, and ecosystems. For example, removal and subsequent regeneration of clams' siphons, polychaetes' segments, and brittlestars' arms can represent significant energetic input to higher trophic levels. In marine soft-sediment habitats, injury changes infaunal bioturbation rates and thus secondarily influences sediment-mediated competition, adult-larval interactions, and recruitment success. The importance of injury and regeneration as factors affecting the ecology of marine invertebrate communities depends on the frequency of injury, as well as on individual capacity for, and speed of, regeneration. A key question to answer is: "How frequently are marine benthic invertebrates injured?" Here, I review the sources and the frequencies of injury in a variety of marine invertebrates from different benthic habitats, discuss challenges, and approaches for accurately determining injury rates in the field, consider evidence for species-specific, temporal and geographic variation in injury rates, and present examples of indirect effects of injury on marine invertebrates to illustrate how injury and regeneration can modify larger-scale ecological patterns and processes.     

Community structure and spatial distribution of benthic fauna in the Bellingshausen Sea (West Antarctica)

The structure and spatial distribution of the macrofauna community of the Bellingshausen Sea in the western sector of Antarctica was studied during the ‘BENTART–06’ oceanographic expedition. This is one of the least explored Antarctic seas. A total of 20 box cores were sampled at 11 stations ranging from 157 to 3,304 m depth, using an USNEL-type box corer (BC) dredge. Representatives of 25 higher taxa of invertebrates were collected. Deeper sampling sites were less rich in taxa (4–7 taxa), whereas the figures were higher at shallower sites (up to 17 taxa). Faunal density on the sea bottom revealed a horizontal spatial gradient from the western sites with extremely low figures (90 indiv./m²) towards the eastern ones with the highest figures (1,360 indiv./m²) close to the Antarctic Peninsula. Several abiotic factors (depth, redox, organic matter, carbonates and particle size of surficial sediments) were measured simultaneously on the sea floor to characterise the substrate preferences of the fauna. Positive correlations were found between the faunal distribution and a combination of depth, redox values, and organic matter content of sediments. This indicates decreasing availability of food in the deeper bottoms of the Bellingshausen Sea with a prevalence of depauperated bottoms dominated almost exclusively by a foraminiferans community.     

Patterns and processes in abundance-body size relationships for marine benthic invertebrates

1. The nature of abundance-body size relationships in animal communities, and especially the drivers behind the observed patterns, have been a focus of persistent debate in animal ecology. In a recent review, Allen et al. (2006) categorized five mechanistic explanations behind the commonly observed polymodality in these relationships: energetic constraints; phylogenetic constraints; biogeographical determinants; habitat structure; and community interactions. Progress in understanding of these patterns and the processes underlying them have been hindered by the use of a range of methods that differ in their validity and robustness. 2. Here, we used data on invertebrate body sizes from a variety of sandy beaches in the UK to test the hypothesis that these communities display modality in their abundance-body size relationships. We quantified modality in the relationships using kernel density estimation and smoothed bootstrap resampling and then evaluated the competing explanations for this modality based on the patterns identified in conjunction with measurements of the physical beach environment. 3. We found bimodal distributions in the body size spectrum for benthic invertebrates at nine of 16 sites. There was a consistent trough in the spectrum at around 0·5-1 mm diameter, which reflected the traditional split between meiofauna and macrofauna. Beaches with finer particle sizes and more heterogeneous macrofauna hosted communities with more than two modes. 4. Our results suggest that modality in sandy beach benthic communities is unlikely to be explained by any single hypothesis. There will be an interplay between physical and biological factors, with different explanations accounting for modality at different scales.     

The benthic invertebrates of the Salton Sea: distribution and seasonal dynamics

The Salton Sea, California's largest inland water body, is an athalassic saline lake with an invertebrate fauna dominated by marine species. The distribution and seasonal dynamics of the benthic macroinvertebrate populations of the Salton Sea were investigated during 1999 in the first survey of the benthos since 1956. Invertebrates were sampled from sediments at depths of 2–12 m, shallow water rocky substrates, and littoral barnacle shell substrates. The macroinvertebrates of the Salton Sea consist of a few invasive, euryhaline species, several of which thrive on different substrates. The principal infaunal organisms are the polychaetes Neanthes succinea Frey & Leuckart and Streblospio benedicti Webster, and the oligochaetes Thalassodrilides gurwitschi Cook, T. belli Hrabe, and an enchytraeid. All but Neanthes are new records for the Sea. Benthic crustacean species are the amphipods Gammarus mucronatus Say, Corophium louisianum Shoemaker, and the barnacle Balanus amphitrite Darwin. Neanthes succinea is the dominant infaunal species on the Sea bottom at depths of 2–12 m. Area-weighted estimates of N. succinea standing stock in September and November 1999 were two orders of magnitude lower than biomass estimated in the same months in 1956. During 1999, population density varied spatially and temporally. Abundance declined greatly in offshore sediments at depths >2 m during spring and summer due to decreasing oxygen levels at the sediment surface, eventually resulting in the absence of Neanthes from all offshore sites >2 m between July and November. In contrast, on shoreline rocky substrate, Neanthes persisted year round, and biomass density increased nearly one order of magnitude between January and November. The rocky shoreline had the highest numbers of invertebrates per unit area, exceeding those reported by other published sources for Neanthes, Gammarus mucronatus, Corophium louisianum, and Balanus amphitrite in marine coastal habitats. The rocky shoreline habitat is highly productive, and is an important refuge during periods of seasonal anoxia for Neanthes and for the other invertebrates that also serve as prey for fish and birds.     

Oceanographic characteristics of the habitat of benthic fish and invertebrates in the Beaufort Sea

We relate the spatial variability in the distribution of benthic taxa of the Beaufort Sea to oceanographic characteristics of their habitat with the goal of illustrating potential mechanisms linking climate change to Arctic marine communities. Offshore fish of the Beaufort Sea have not been surveyed since 1977 and no synchronous measures of fish distribution and the oceanographic characteristics of their habitat have been made previously. A survey was conducted during August 2008 in the western Beaufort Sea, Alaska. The distribution and abundance of benthic fish and invertebrates were assessed with standard bottom trawl survey methods. Oceanographic data were collected at each trawl station and at several locations between stations. The dominant benthic taxa, Polar cod (Boreogadus saida), eelpouts (Lycodes sp.), and snow crab (Chionoecetes opilio) were associated with cold (<?1.5°C), high salinity (>33) water found offshore of the shelf break, derived from the Chukchi Sea. These waters are expected to be high in secondary productivity, such that we hypothesize that the distribution of fish and crab was driven by conditions favorable for successful foraging. Predictions of the impacts of climate change require an understanding of the mechanisms linking the distribution and abundance of marine organisms to their oceanographic habitat. Our study documents the association of dominant benthic fish and invertebrates of the Beaufort Sea with specific water mass types and is thus a step toward this understanding.     

东海浮游磷虾类的生态类型

根据1997～2000年东海23°30'～33°00'N、118°30'～128°00'E海域4个季节海洋调查,运用磷虾类物种丰度和同步的温、盐度资料,进行曲线拟合,构造数学模型,计算各种磷虾分布的最适温度和盐度,并参考其地理和季节分布特征,对东海浮游磷虾类生态类型进行定量分析.结果表明,在磷虾优势种中,太平洋磷虾(Euphausia pacifica)是温带外海种,小型磷虾(E. nana)是暖温带外海种,中华假磷虾(Pseudeuphausia sinica)是亚热带近海种,宽额假磷虾(P. latifrons)是热带大洋种.这些物种的高丰度区依次代表黄海冷水团,冬春季的混合水团,夏秋季的混合水团和暖流水团的位置,是良好的水团指示种.柔弱磷虾(E. tenera)、隆柱螯磷虾(Stylocheiron carinatum)、长额磷虾(E. diomedeae)、近缘柱螯磷虾(S. affine)、Nematoscelis sp.、瘦线脚磷虾(N. gracilis)、长线脚磷虾(N. atlantica)、Stylocheiron sp.、三晶柱螯磷虾(S. suhmii)和二晶柱螯磷虾(S. microphthalma)是热带大洋种.娇嫩线脚磷虾(Nematoscelis tenella)、三刺燧磷虾(Thysanopoda tricuspidata)、大眼磷虾(E. sanzoi)、拟磷虾(E. similis)、鸟喙磷虾(E. mutica)、短磷虾(E. brevis)、卷叶磷虾(E. recurva)和Euphausia sp.是亚热带外海种.在确定磷虾类生态类型过程中,最适温度具有更好的参考价值.     

Distribution patterns of pelagic euphausiids in the East China Sea

Distribution patterns and abundance of the euphausiids were examined in the East China Sea (23°30′ –33°00′N, 118°30′ –128°00′ E) in relation to temperature and salinity. The data were collected in 4 surveys from 1997 to 2000. The density or yield density model was used to predict optimum temperature and salinity of water for euphausiid distribution, and thereafter distribution patterns of euphausiids were determined based on the predicted parameters. Of 23 species, Euphausia pacifica, E. nana, Pseudeuphausia sinica and P. latifrons were numerically dominant. The analyses indicate that Euphausia pacifica is an offshore temperate water species, E. nana is an offshore temperate warm water species, P. sinica is a coastal subtropical water species and P. latifrons is an oceanic tropical water species. The 4 species occupied 4 different water masses, respectively, namely, cold water mass, cold and warm water mixed masses in winter and spring, cold and warm water mixed masses in summer and autumn, and warm water mass, which could be the good designators of individual water masses, respectively. The predicated optimal temperatures for E. tenera, S. carinatum, E. diomedeae, Stylocheiron affine, Nematoscelis sp., N. gracilis, N. atlantica, Stylocheiron sp. and S. suhmii are all > 25°. These species are mainly distributed in southern Kuroshio in winter and spring, Kuroshio, the Taiwan Warm Current and Tsushima Current in summer and autumn, the equatorial waters of Pacific Ocean and the eastern waters of the Taiwan Strait. They are called as oceanic tropical water species. Nematoscelis tenella and T. tricuspidata are referred to as offshore subtropical water species according to their geographic distributions even if they are halobionts. Euphausia sanzoi is considered as a typical offshore subtropical water species, which inhabited waters below 25°. Stylocheiron microphthalma, occupying warm current waters where temperature and salinity are nearly 25° and 34 in summer and autumn, belongs to oceanic tropical water species. In the same way, E. similes, E. mutica, Euphausia sp., E. brevis and E. recurva are classified into offshore subtropical water species in accordance with the optimum temperature and salinity of waters as well as locations and seasons of their occurrence. Optimum temperature, rather than salinity, is a better parameter in determining the distribution patterns of euphausiids.     

Overview of the chemical ecology of benthic marine invertebrates along the western Antarctic peninsula

Thirteen years ago in a review that appeared in the American Zoologist, we presented the first survey of the chemical and ecological bioactivity of Antarctic shallow-water marine invertebrates. In essence, we reported that despite theoretical predictions to the contrary the incidence of chemical defenses among sessile and sluggish Antarctic marine invertebrates was widespread. Since that time we and others have significantly expanded upon the base of knowledge of Antarctic marine invertebrates' chemical ecology, both from the perspective of examining marine invertebrates in new, distinct geographic provinces, as well as broadening the evaluation of the ecological significance of secondary metabolites. Importantly, many of these studies have been framed within established theoretical constructs, particularly the Optimal Defense Theory. In the present article, we review the current knowledge of chemical ecology of benthic marine invertebrates comprising communities along the Western Antarctic Peninsula (WAP), a region of Antarctica that is both physically and biologically distinct from the rest of the continent. Our overview indicates that, similar to other regions of Antarctica, anti-predator chemical defenses are widespread among species occurring along the WAP. In some groups, such as the sponges, the incidence of chemical defenses against predation is comparable to, or even slightly higher than, that found in tropical marine systems. While there is substantial knowledge of the chemical defenses of benthic marine invertebrates against predators, much less is known about chemical anti-foulants. The sole survey conducted to date suggests that secondary metabolites in benthic sponges are likely to be important in the prevention of fouling by benthic diatoms, yet generally lack activity against marine bacteria. Our understanding of the sensory ecology of Antarctic benthic marine invertebrates, despite its great potential, remains in its infancy. For example, along the WAP, community-level non-consumptive effects occur when amphipods chemically sense fish predators and respond by seeking refuge in chemically-defended macroalgae. Such interactions may be important in releasing amphipods from predation pressure and facilitating their unusually high abundances along the WAP. Moreover, recent studies on the sensory biology of the Antarctic keystone sea star Odontaster validus indicate that chemotactile-mediated interactions between conspecifics and other sympatric predatory sea stars may have significant ramifications in structuring community dynamics. Finally, from a global environmental perspective, understanding how chemical ecology structures marine benthic communities along the WAP must increasingly be viewed in the context of the dramatic impacts of rapid climatic change now occurring in this biogeographic region.     

Chemical monitoring in the Dutch Wadden Sea by means of benthic invertebrates and fish

In monitoring, it is of utmost importance to carefully define the purpose, the sampling strategy, as well as the analytical chemical and statistical requirements. Surveys are appropriate for describing the geographical variation in environmental contaminant levels. Repeated surveys and recurrentdata collection at permanent locations provide means of detecting temporal trends. Results are presented here of surveys on pollution by trace metals, polychlorinated biphenyls and organochlorine pesticides in the Ems Estuary and Dutch Wadden Sea usingMytilus edulis, Mya arenaria, Arenicoia marina, Nereis diversicolor andCrangon crangon as test organisms. Trends towards decreasing pollution by mercury are illustrated by monitoring data onMytilus edulis andZoarces viviparus. It is stressed that the results of chemical monitoring in organisms may be interpreted only in termser the biological effects on the basis of relevant toxicological knowledge and/or additional bio-assays. Presented at the VI International Wadden Sea Symposium (Biologische Anstalt Helgoland Wattenmeerstation Sylt, D-2282 List, FRG, 1–4 November 1988)     

Temperature tracking by North Sea benthic invertebrates in response to climate change

Climate change is a major threat to biodiversity and distributions shifts are one of the most significant threats to global warming, but the extent to which these shifts keep pace with a changing climate is yet uncertain. Understanding the factors governing range shifts is crucial for conservation management to anticipate patterns of biodiversity distribution under future anthropogenic climate change. Soft‐sediment invertebrates are a key faunal group because of their role in marine biogeochemistry and as a food source for commercial fish species. However, little information exists on their response to climate change. Here, we evaluate changes in the distribution of 65 North Sea benthic invertebrate species between 1986 and 2000 by examining their geographic, bathymetric and thermal niche shifts and test whether species are tracking their thermal niche as defined by minimum, mean or maximum sea bottom (SBT) and surface (SST) temperatures. Temperatures increased in the whole North Sea with many benthic invertebrates showing north‐westerly range shifts (leading/trailing edges as well as distribution centroids) and deepening. Nevertheless, distribution shifts for most species (3.8–7.3 km yr^?1 interquantile range) lagged behind shifts in both SBT and SST (mean 8.1 km yr^?1), resulting in many species experiencing increasing temperatures. The velocity of climate change (VoCC) of mean SST accurately predicted both the direction and magnitude of distribution centroid shifts, while maximum SST did the same for contraction of the trailing edge. The VoCC of SBT was not a good predictor of range shifts. No good predictor of expansions of the leading edge was found. Our results show that invertebrates need to shift at different rates and directions to track the climate velocities of different temperature measures, and are therefore lagging behind most temperature measures. If these species cannot withstand a change in thermal habitat, this could ultimately lead to a drop in benthic biodiversity.     

Distribution pattern analysis in a marine benthic community

Summary 1. 256 contiguous core samples (7.62 cm diameter) were collected along a 32 m straight line transect from a sandy mud substrate in Fanafjorden, Norway, at a depth of 35 m.2. Eleven species found in the community were analysed usingGreig Smith's method of pattern analysis.3. Three species were aggregated at nearly all block sizes (i. e. the effective sample sizes) and five randomly distributed.4. Three species showed fluctuating distribution patterns according to the block size. The distributions of these species could not be adequately studied from multiple random samples.5. No species showed an even distribution at any block size.6. It is concluded that the micro-distributions, and hence the micro-habitats, of infaunal species cannot be investigated using the more conventional sampling techniques for sampling the benthos, by grab, scoop or ship-operated corers.

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Verteilungsmuster-Analyse in einer marinen benthonischen Lebensgemeinschaft

Kurzfassung Über die Mikroverteilungsmuster innerhalb der Tiergesellschaften des ozeanischen Benthals ist wenig bekannt. Derartige Informationen sind aber wesentlich für eine Beurteilung der Vorgänge bei der Probenentnahme und die Analyse der Mikrofundorte der vorhandenen Arten. In Fanafjorden, Norwegen, wurden entlang einer geraden Schnittlinie in einer Tiefe von 35 m 256 benachbarte Kernproben (Ø 7,62 cm) entnommen. Alle von einem 0,5-mm-Sieb zurückgehaltenen Tiere wurden extrahiert und die Verteilungsbilder von elf Arten mittels der Bildanalysentechnik vonGreig Smith (1957, 1961) analysiert. Diese Methode beruht darauf, daß die Befunde in Blöcken von stufenweise steigender Größe — mit Inhalten von (2ⁿ) Proben — dargestellt werden. Drei Arten,Myriochele heeri, Astrorhiza limicola undLabidoplax buski, waren in fast allen Blockgrößen aggregiert. Fünf Arten,Goniada maculata, Nephtys sp.,Leptosynapta decaria, Lucinoma borealis undDentalium entalis, waren in fast allen Blockgrößen regellos verteilt. Drei weitere Arten,Thyasira flexuosa, Owenia fusiformis undEuphisa aurata, zeigten je nach Größe der Probe wechselnde Verteilungsbilder. Die Neigung einer Art zur Aggregation nimmt mit steigender Siedlungsdichte zu. Keine der untersuchten Arten wies bei irgendeiner Blockgröße eine regelmäßige Verteilung auf. Die Bedeutung dieser Ergebnisse für die multiple Stichprobenentnahme wird besprochen; es wird der Schluß gezogen, daß eine solche Stichprobenentnahme für eine Beurteilung der Mikroverteilung unzureichend ist.

     

海洋沉积物中重金属对底栖无脊椎动物的生物有效性

海洋沉积物是重金属的重要贮库,而海洋底栖无脊椎动物主要从沉积物中摄取重金属,这些被摄取的重金属能够通过食物链进行传递,进而影响到人类健康。本文总结了近些年来在海洋沉积物中重金属对底栖无脊椎动物生物有效性方面的研究进展,包括海洋底栖无脊椎动物对重金属的吸收途径、沉积物地球化学性质和底栖无脊椎动物生理等生物因素对沉积物中重金属生物有效性的影响。在此基础上,展望了未来研究重点,主要包括近海富营养化对沉积物中重金属生物有效性的影响,海洋底栖无脊椎动物消化道中的物理消化过程对沉积物中重金属生物有效性的影响,海洋底栖无脊椎动物整个生活史过程中沉积物中重金属生物有效性的变化等。     

Energetic constraints, size gradients, and size limits in benthic marine invertebrates

Populations of marine benthic organisms occupy habitats witha range of physical and biological characteristics. In the intertidalzone, energetic costs increase with temperature and aerial exposure,and prey intake increases with immersion time, generating sizegradients with small individuals often found at upper limitsof distribution. Wave action can have similar effects, limitingfeeding time or success, although certain species benefit fromwave dislodgment of their prey; this also results in gradientsof size and morphology. The difference between energy intakeand metabolic (and/or behavioral) costs can be used to determinean energetic optimal size for individuals in such populations.Comparisons of the energetic optimal size to the maximum predictedsize based on mechanical constraints, and the ensuing mortalityschedule, provides a mechanism to study and explain organismsize gradients in intertidal and subtidal habitats. For specieswhere the energetic optimal size is well below the maximum sizethat could persist under a certain set of wave/flow conditions,it is probable that energetic constraints dominate. When theopposite is true, populations of small individuals can dominatehabitats with strong dislodgment or damage probability. Whenthe maximum size of individuals is far below either energeticoptima or mechanical limits, other sources of mortality (e.g.,predation) may favor energy allocation to early reproductionrather than to continued growth. Predictions based on optimalsize models have been tested for a variety of intertidal andsubtidal invertebrates including sea anemones, corals, and octocorals.This paper provides a review of the optimal size concept, andemploys a combination of the optimal energetic size model andlife history modeling approach to explore energy allocationto growth or reproduction as the optimal size is approached.