摘要:

Abstract.Coastal Patagonian sea waters had been differentially nutrient‐enriched to determine (i) the magnitude of the algal biomass supported and (ii) which species were able to best compete for the available nutrients. Nitrogen was found to be the nutrient limiting growth of the natural phytoplankton population. The addition of NO3at 25 μg at 1‐1led to a 10 to 30 μg 1‐1increase in chlorophyllain all but those treatments containing trace metal additions. The best yield coefficients were obtained when a chelator (EDTA) was added with NO3. A pool of nine diatom species were common in the N03supplemented waters and the addition of vitamins along with NO3allowed two of the nine species to d

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1983.tb00285.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract.The biology of the thalassinidean shrimpUpogebia pusillawas studied on a tidal flat in the Lagoon of Grado (Northern Adriatic). Burrows were investigated usingin situresin casting and with additionalin situand laboratory observations. Burrows show a basic pattern consisting of a U or a double U with turning chambers and a vertical shaft. Mean burrow diameter depends on animal size, it is smaller than the rigid carapace of the animal. Dimensions, distance between openings, depth of U, total depth, volume and surface are size dependent. The burrow wall is smooth and oxidized. Burrows are always inhabited by a single shrimp. Although they overlap, they are never interconnected. They are mainly constructed by compression of the sediment and are relatively permanent structures. A comparison of the burrows ofThalassinideawith regard to shape, number and appearance of openings, dimensions, properties of the burrow wall and dynamics is given.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1983.tb00286.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract.Biokarst‐forms on limestone coasts are developed and arranged according to the bionomic zonation. The development of biokarst is the result of bioerosion, a synergistic effect of biological corrosion by endoliths and biological abrasion by grazers.The cumulative effect of biogenic carbonate destruction leads to coastal destruction with a resulting highly profiled morphology on the limestone surfaces along the coastal profile. Under the influence of environmental factors a zonation of organisms develops which brings in turn a zonation of erosion rates (0.1‐1.1 mm a‐1) resulting in biokarst‐forms such as rock holes, rock pools and notches.Products of bioerosion on limestone coasts are dissolved carbonate (by biological corrosion, 10–30% of the decomposed limestone) and particulate carbonate (by biological abrasion, 70–90% of the decomposed limestone) both of which contribute directly or indirectly to nearshore sedimentation. Size and shape of the bioerosional grains are determined by the boring pattern of the endoliths. The fine‐grained sediments (maximum within the fraction 20–63 μm) contribute 3–25 % to the nearshore sediments.Drastic changes in the biological zonation (like the mass invasion of the sea urchinParacentrotus lividusin the Northern Adriatic since 1972 which eliminated nearly the entire macrophyte zone) due to unknown factors or pollution can have a profound effect on the bioerosion rates, altering them by as much

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1983.tb00287.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract.Branchiosyllis oculatais a small, errant polychaete that lives only on the surface of sponges: among inshore Bermudian sponges, 9 out of 16 species surveyed were infested. All of these sponges were conspicuously colored, but the bodies and gut contents of associated polychaetes matched the sponge color only forTedania ignis(red),Cinachyra alloclada(yellow) andSphecio‐spongia othella(brownish‐black). For the remaining 6 sponge species, the polychaete bodies were uncolored and the polychaete gut contents were inconspicuously brown or grey. Uncolored polychaetes with grey gut contents were removed from a dark greenTethya actiniaand placed on a redTedania ignis: 2 days later, the polychaete gut contents were red, although the tissues were still uncolored. Acetone extractions ofTedania ignisandCinachyra allocladawere prepared from sponge tissue and from the gut‐free tissue of their respective polychaetes: absorption spectra matched for each sponge/polychaete pair. To test the influence of ingested sponge pigments on polychaete body color, red polychaetes fromTedania igniswere induced to autotomize their posterior ends, transplanted to other sponge species and allowed to regenerate new posterior segments for 20 days. At the end of the experiment the original segments were still red, but the regenerated ones were either yellow (for polychaetes transplanted ontoCinachyra alloclada, on which resident worms are yellow) or colorless (for polychaetes transplanted ontoChondrilla nuculaorTethya actinia, on which resident worms are uncolored). The foregoing observations suggest that (1) the polychaetes consume the soft parts of the sponges on which they live and (2) the pigments vary among sponge species: pigments from some sponges are stored in the polychaete body, while pigments from other sponges are not. Additional information on the morphology, distribution and natural history ofBranchiosyllis oculatais presented and disc

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1983.tb00288.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract.Synoptic measurements of temperature, salinity, nutrients, primary productivity, chlorophylla, and abundance and composition of phytoplankton, zooplankton, and ichthyoplank‐ton were made over an annual cycle on the Peconic Bay estuary (Long Island, New York, USA).There were pronounced seasonal fluctuations in all variables measured. During the warmer season, the plankton was dominated by nanophytoplankton (athecate microflagellates and chlorophytes, short chains of diatoms), small zooplankton (copepod nauplii, copepodites, and adults of small copepod species) and gelatinous carnivores (ctenophores and medusae). During the colder season, the plankton was dominated (in terms of primary productivity and chlorophylla) by netplankton, larger zooplankton (adult copepods) and fish larvae. The winter bloom of apparent netplankton (>20 μm fraction) was largely an artifact of the screening method employed, in that long chains of a diatom with small individual cell size (Skeletonema costatum) comprised 84.4–97.8% of the phytoplankton present. There was a significant negative relationship over the year between length of diatom chains and number of smaller zooplankton. For this reason, as well as initiation of the winter bloom during a period of declining levels of both light and zooplankton, inception of the bloom appeared more related to release of zooplankton grazing pressure than to illumination. Temporally offset pulses of ctenophores and other zooplankton during the warmer season suggest substantial predation by ctenophores. Apparent decimation of copepod populations by ctenophore predation in late summer and fall immediately preceeded inception of the winter diatom bloom. LarvalAmmodytes americanuswere the dominant ichthyoplankton, and these co‐occurred in winter with increased abundances of larger adult copepods of species upon whichA. americanusis known to feed. With certain modifications the patterns recorded for Peconic Bay corresponded to both of two generalized trophic pathways proposed by Greve&Parsons(1977) for temperate waters: nanoplankton → small zooplankton → gelatinous zooplankton carnivores ornetplankton → larger zooplankton → young fish.The former pattern characterized the warmer season, and the latter the colder season. Comparison of patterns in Peconic Bay with those in some other temperate estuarine and coastal waters suggests similarity, particularly for estuaries of the northeastern

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1983.tb00289.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY