The distribution and temporal dynamics of the estuarine macroalgal community of San Francisco Bay

Josselyn, Michael; West, John A.

doi:10.1007/bf00048692

Cited by 33 publications

(16 citation statements)

References 32 publications

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“…Talbot et al (1990) observed that aquatic macrophyte communities are relatively stable in the absence of large freshwater flows in South African estuaries, while in the event of a large flow, macrophyte populations are severely diminished, if not removed entirely. Josselyn and West (1985) also suggest that freshwater flow in estuaries is a short-term process affecting unattached macroalgal accumulations. The observations of this study are of individual algal plants assumed as being representative of whole accumulations.…”

Section: Discussionmentioning

confidence: 95%

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The dynamics of unattached benthic macroalgal accumulations in the Swan–Canning Estuary

Astill

Lavery

2001

Hydrological Processes

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Abstract:It has been suggested that macroalgal accumulations may impact on benthic nutrient cycling by promoting remineralization of sedimentary nutrients, otherwise inaccessible, and act as sinks/sources for dissolved nutrients in the water column. However, little consideration has been given to the time taken for these impacts to occur, and if accumulations persist long enough in a region for impacts to occur. In this study, accumulations were characterized seasonally, according to biomass, height relative to water depth, and organic content of the underlying sediment, from November 1996 to August 1997, in the Swan-Canning Estuary. Persistence of accumulations was measured from late summer to mid-winter in 1997, by tagging individual plants and recording the time tagged plants persisted at 10 sites. In summer 1998, physicochemical profiles of accumulations were measured over 24 h, at two locations: one with relatively low sediment organic content (SOCn) (1Ð5% LOI) and one with relatively high SOC (6% LOI).Accumulations rarely exceeded 25 cm in height, regardless of water column depth, and ranged between 100 and 500 g dwt m 2 . Macroalgae persisted between one week, in relatively well-flushed regions, to one month in areas with poor flushing. Over the entire diurnal period, almost 100% of incident light was attenuated at the bottom of all accumulations. Dissolved oxygen levels at the bottom of accumulations were generally depressed, particularly at night, with hypoxia (1 mg l 1 ) recorded at the high SOC site at 03 : 00 h. No significant differences in FRP concentrations (approximately 30-60 µg l 1 ) were recorded between sites, or within accumulation profiles. Ammonium levels were greatly raised inside accumulations at the high SOC site by 03 : 00 h (10 and 300 µg l 1 , inside and outside, respectively). The results show that, where SOC is high, conditions within accumulations are affected. Impacts occurred within 24 h; well within the period for which accumulations persist. These results also indicate that regulation of hydrological regimes in estuarine systems may result in increased persistence of macroalgal accumulations, and associated water quality problems.

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Section: Discussionmentioning

confidence: 95%

“…The accumulation of unattached macroalgae in estuaries and shallow coastal embayments is widely documented (Peckol and Rivers, 1996;Collado-Vides et al, 1994;Lavery et al, 1991;Josselyn and West, 1985). These accumulations are typically comprised of unattached macroalgae, varying in height, areal cover and biomass.…”

Section: Introductionmentioning

confidence: 99%

The dynamics of unattached benthic macroalgal accumulations in the Swan–Canning Estuary

Astill

Lavery

2001

Hydrological Processes

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“…However, occasional summer blooms of macroalgal species, resulting in localized accumulations of decaying algae and resulting anoxia at the sediment surface (Horne & Nonomura, 1976;Josselyn & West 1985;Nichols & Thompson, 1985), can smother the organisms in the sediments. The recovery process (described in other estuaries as well, e.g., Dauer, 1984) can take from a few weeks to many months depending on the severity and duration of the smothering effect and the availability of colonizing species (Nichols & Thompson, 1985).…”

Section: Introductionmentioning

confidence: 99%

Time scales of change in the San Francisco Bay benthos

Nichols

Thompson

1985

Hydrobiologia

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Results from multi-year investigations in the San Francisco Bay estuary show that large abundance fluctuations within benthic macroinvertebrate populations reflect both (1) within-year periodicity of reproduction, recruitment, and mortality that is not necessarily coincident with seasonal changes of the environment (e.g., the annual temperature cycle), and (2) aperiodic density changes (often larger than within-year fluctuations) following random perturbations of the environment.Density peaks of the small, short-lived estuarine invertebrates that comprise the vast majority of individuals in the bay's relatively homogeneous benthic community normally occur between spring and autumn depending on the species, in large part a reflection of reproductive periodicity. However, because mild winters permit reproductive activity in some of the common species throughout much of the year, other factors are important to within-year density fluctuations in the community. Seasonally predictable changes in freshwater inflow, wind and tidal mixing, microalgal biomass, and sediment erosion/deposition patterns all contribute to observed seasonal changes in abundance. For example, the commonly observed decline in abundance during winter reflects both short-lived species that die after reproducing and the stress of winter conditions (e.g., inundation by less saline, sediment-laden water and the decline in both planktonic and benthic algal biomass -a direct source of food for the shallow-water benthos). On the other hand, data from several studies suggest that observed 'recruitment' and 'mortality' may in fact be the migration of juveniles and adults to and from study sites. For example, the common amphipod Ampelisca abdita apparently moves from shallow to deep water, or from up-estuary to down-estuary locations, coincident with periods of high river runoff in winter. Growth of individuals within the few studied species populations is also highly seasonal, and appears to be coincident with seasonal increases in the abundance of planktonic and/ or benthic microalgae.Two multi-year studies have shown that, in addition to within-year periodicity, major restructuring of the benthic community can occur as a result of anomalous (usually climate-related) perturbations of the benthic habitat. For example, during wet years freshwater-intolerant species disappear from the upper part of the estuary and from shallow areas of the bay. During a two-year drought these same species colonized the extreme upper end of the estuary in large numbers. Other aperiodic perturbations include localized instances of sediment erosion or deposition and algal mat accumulations that greatly depress abundance. Additionally, there is evidence (observations that the clam Macoma balthica establishes large populations only when the amphipod A. abdita is not abundant) that species interactions can contribute greatly to interannual variations. Thus, while community composition may change little over the long term, year-to-year predictability of species abundances is low.

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“…Kelps (macroalgae of the Order Laminariales) are usually the dominant habitat forming organisms in temperate shallow subtidal reefs around the world (Steneck et al 2002) fragile are common and abundant (Josselyn and West 1985). A consequence of the presence of these kelp beds is the great biological diversity that occurs in and around subtidal reefs in this estuary.…”

Section: The Natural Habitats Of Sydney Harbour Subtidal Rocky Reefsmentioning

confidence: 99%

Sydney Harbour: what we do and do not know about a highly diverse estuary

Johnston

Mayer‐Pinto

Hutchings

et al. 2015

Mar. Freshwater Res.

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Sydney Harbour is a global hotspot for marine and estuarine diversity. Despite its social, economic and biological value, the available knowledge has not previously been reviewed or synthesised. We systematically reviewed the published literature and consulted experts to establish our current understanding of the Harbour’s natural systems, identify knowledge gaps, and compare Sydney Harbour to other major estuaries worldwide. Of the 110 studies in our review, 81 focussed on ecology or biology, six on the chemistry, 10 on geology and 11 on oceanography. Subtidal rocky reef habitats were the most studied, with a focus on habitat forming macroalgae. In total 586 fish species have been recorded from the Harbour, which is high relative to other major estuaries worldwide. There has been a lack of process studies, and an almost complete absence of substantial time series that constrains our capacity to identify trends, environmental thresholds or major drivers of biotic interactions. We also highlight a lack of knowledge on the ecological functioning of Sydney Harbour, including studies on microbial communities. A sound understanding of the complexity, connectivity and dynamics underlying ecosystem functioning will allow further advances in management for the Harbour and for similarly modified estuaries around the world.

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The distribution and temporal dynamics of the estuarine macroalgal community of San Francisco Bay

Cited by 33 publications

References 32 publications

The dynamics of unattached benthic macroalgal accumulations in the Swan–Canning Estuary

The dynamics of unattached benthic macroalgal accumulations in the Swan–Canning Estuary

Time scales of change in the San Francisco Bay benthos

Sydney Harbour: what we do and do not know about a highly diverse estuary

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