Seasonal and Long-Term Phytoplankton Dynamics in the Middle Caspian According to Satellite Data and In Situ Observations in the First Decades of the 21st Century

Round 1

Reviewer 1 Report

See the attached file. One additional comment: where did you get SST data - add to methods.

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Little is known of phytoplankton dynamics of the Caspian Sea, and as such this 1998-2021 (23 yr) satellite chlorophyll data set is valuable, notably because it is interpreted against the background of mostly diatom and dinoflagellate species composition data.

Repeated reference is made to the "invasive" phytoplankton species Pseudo-nitzschia seriata, Cerataulina pelagica, Chaetoceros peruvianus. This term "invasive" tends to be used for introduced species that exhibit harmful invasive (outcompeting) behaviour such as the ctenophore Mnemiopsis. What is the evidence for this? as this would require long-term plankton or sediment records or even molecular strain taxonomy. All 3 microalgal taxa would be expected to naturally occur in this region, with the warm-water Ch. peruvianus perhaps a seasonal intruder.

The only environmental parameter invoked in interpreting the phytoplankton biomass is surface water temperature Fig.3. Are there any data on water column stratification, nutrients, perhaps zooplankton or fisheries data (perhaps even Mnemiopsis blooms) that match these patterns?

I highlighted in attached ms version bits that need attention. (without line numbers it is difficult to provide a more detailed review)

Title best should define the period 1998 to 2021; no full stop at end, Caspian Sea?

Abstract. constituted=composed of

Note repeated misspelling of Pseudo-nitzschia seriata , in abstract, p.6 bottom, but also Prorocentrum micans (p.12, 14) 

Repeated reference to "the current period" should define what this period is ? past 23 yrs

Formaldehyde is OK for diatoms and armoured dinoflagellates, but may destroy fragile flagellates. This is OK because the latter are unlikely to make major chlorophyll contributions.

The Chlorophyll axis in Fig.3 should read mg/m3

The seasons in Fig 5 should be in English

p.6, 7. improve the lay-out of Tables 1 and 2, closer spacing and not running on to the next page.

p.10. Was Microcystis a toxin producer?

All species names should be in italics

p.7 biomass of 1 g/m3. Is this a volume estimate converted to carbon or dry weight?

p.11, Structural restructuring=? Community restructuring

p.13. Coscinodiscus is misspelled

p.14 nitzschioides is misspelled

ref 55 should not be underlined

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.pdf